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Sample records for evaporative cooling

  1. Indirect evaporative cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Wooldridge, M.J.; Chapman, H.L.; Pescod, D.

    1976-01-01

    Characteristics and applications of three indirect evaporative cooling systems are described. The rock bed regenerative unit is now in licensed production and some operational experience is available, while the plastic plate heat exchanger unit has been demonstrated to be effective. A third system, based on a rotary heat exchanger is included. Although less development has been done on it, several successful applications of the heat exchanger are operational. All systems provide comfort cooling in which building indoor temperature varies over the day at an operating cost less than 50% of that of a comparable refrigerated cooling system.

  2. Cooling clothing utilizing water evaporation

    DEFF Research Database (Denmark)

    Sakoi, Tomonori; Tominaga, Naoto; Melikov, Arsen Krikor

    2014-01-01

    We developed cooling clothing that utilizes water evaporation to cool the human body and has a mechanism to control the cooling intensity. Clean water was supplied to the outer surface of the T-shirt of the cooling clothing, and a small fan was used to enhance evaporation on this outer surface....... To prevent wet discomfort, the T-shirt was made of a polyester material having a water-repellent silicon coating on the inner surface. The chest, front upper arms, and nape of the neck were adopted as the cooling areas of the human body. We conducted human subject experiments in an office with air...... temperature ranging from 27.4 to 30.7 °C to establish a suitable water supply control method. A water supply control method that prevents water accumulation in the T-shirt and water dribbling was validated; this method is established based on the concept of the water evaporation capacity under the applied...

  3. Intrinsic Evaporative Cooling by Hygroscopic Earth Materials

    National Research Council Canada - National Science Library

    Rempel, Alexandra; Rempel, Alan

    2016-01-01

    .... Diverse evaporative cooling strategies have resulted worldwide, including roof ponds and sprinklers, courtyard fountains, wind catchers with qanats, irrigated green roofs, and fan-assisted evaporative coolers...

  4. Evaporative Cooling Availability in Water Based Sensible Cooling Systems

    OpenAIRE

    Costelloe, Ben; Finn, Donal

    2001-01-01

    Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, such as chilled ceilings, which require a supply of cooling water at 14 to 18°C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, ...

  5. Intrinsic Evaporative Cooling by Hygroscopic Earth Materials

    Directory of Open Access Journals (Sweden)

    Alexandra R. Rempel

    2016-08-01

    Full Text Available The phase change of water from liquid to vapor is one of the most energy-intensive physical processes in nature, giving it immense potential for cooling. Diverse evaporative cooling strategies have resulted worldwide, including roof ponds and sprinklers, courtyard fountains, wind catchers with qanats, irrigated green roofs, and fan-assisted evaporative coolers. These methods all require water in bulk liquid form. The evaporation of moisture that has been sorbed from the atmosphere by hygroscopic materials is equally energy-intensive, however, yet has not been examined for its cooling potential. In arid and semi-arid climates, hygroscopic earth buildings occur widely and are known to maintain comfortable indoor temperatures, but evaporation of moisture from their walls and roofs has been regarded as unimportant since water scarcity limits irrigation and rainfall; instead, their cool interiors are attributed to well-established mass effects in delaying the transmission of sensible gains. Here, we investigate the cooling accomplished by daily cycles of moisture sorption and evaporation which, requiring only ambient humidity, we designate as “intrinsic” evaporative cooling. Connecting recent soil science to heat and moisture transport studies in building materials, we use soils, adobe, cob, unfired earth bricks, rammed earth, and limestone to reveal the effects of numerous parameters (temperature and relative humidity, material orientation, thickness, moisture retention properties, vapor diffusion resistance, and liquid transport properties on the magnitude of intrinsic evaporative cooling and the stabilization of indoor relative humidity. We further synthesize these effects into concrete design guidance. Together, these results show that earth buildings in diverse climates have significant potential to cool themselves evaporatively through sorption of moisture from humid night air and evaporation during the following day’s heat. This finding

  6. EVAPORATIVE COOLING - CONCEPTUAL DESIGN FOR ATLAS SCT

    CERN Document Server

    Niinikoski, T O

    1998-01-01

    The conceptual design of an evaporative two-phase flow cooling system for the ATLAS SCT detector is described, using perfluorinated propane (C3F8) as a coolant. Comparison with perfluorinated butane (C4F10) is made, although the detailed design is presented only for C3F8. The two-phase pressure drop and heat transfer coefficient are calculated in order to determine the dimensions of the cooling pipes and module contacts for the Barrel SCT. The region in which the flow is homogeneous is determined. The cooling cycle, pipework, compressor, heat exchangers and other main elements of the system are calculated in order to be able to discuss the system control, safety and reliability. Evaporative cooling appears to be substantially better than the binary ice system from the point of view of safety, reliability, detector thickness, heat transfer coefficient, cost and simplicity.

  7. Dew Point Evaporative Comfort Cooling

    Science.gov (United States)

    2013-07-01

    Laboratory O&M operations and maintenance OA outdoor air OAT outside air temperature PSZ packaged single zone RA return air RAT return air...Barracks 29 Headquarters 17 Offices 5.7 Hospital 4.6 Retail space 1.8 Commissaries 0.9 The OATs are typically 80°–90°F during the cooling season...units were installed across five facilities at Fort Carson, including a training center (classrooms), auditorium, events center, a digester facility

  8. Evaporative cooling: Effective latent heat of evaporation in relation to evaporation distance from the skin

    NARCIS (Netherlands)

    Havenith, G.; Bröde, P.; Hartog, E.A. den; Kuklane, K.; Holmer, I.; Rossi, R.M.; Richards, M.; Farnworth, B.; Wang, X.

    2013-01-01

    Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available, which has

  9. Computational Fluid Dynamics Analysis of an Evaporative Cooling System

    Directory of Open Access Journals (Sweden)

    Kapilan N.

    2016-11-01

    Full Text Available The use of chlorofluorocarbon based refrigerants in the air-conditioning system increases the global warming and causes the climate change. The climate change is expected to present a number of challenges for the built environment and an evaporative cooling system is one of the simplest and environmentally friendly cooling system. The evaporative cooling system is most widely used in summer and in rural and urban areas of India for human comfort. In evaporative cooling system, the addition of water into air reduces the temperature of the air as the energy needed to evaporate the water is taken from the air. Computational fluid dynamics is a numerical analysis and was used to analyse the evaporative cooling system. The CFD results are matches with the experimental results.

  10. Technical potential of evaporative cooling in Danish and European condition

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Andersen, Christian Hede; Heiselberg, Per Kvols

    2015-01-01

    Evaporative cooling is a very interesting high temperature cooling solution that has potential to save energy comparing to refrigerant cooling systems and at the same time provide more cooling reliability than mechanical or natural ventilation system without cooling. Technical cooling potential...... of 5 different evaporative systems integrated in the ventilation system is investigated in this article. Annual analysis is conducted based on hourly weather data for 15 cities located in Denmark and 123 European cities. Investigated systems are direct, indirect, combinations of direct and indirect...

  11. The Evaporative Cooling System for the ATLAS Inner Detector

    CERN Document Server

    Aitree, D; Anderssen, E C; Akhnazarov, V; Apsimon, R J; Barclay, P; Batchelor, L E; Bates, R L; Battistin, M; Bendotti, J; Berry, S; Bitadze, A; Bizzel, J P; Bonneau, P; Bosteels, Michel; Butterworth, J M; Butterworth, S; Carter, A A; Carter, J R; Catinaccio, A; Corbaz, F; Danielsson, H O; Danilevich, E; Dixon, N; Dixon, S D; Doherty, F; Dorholt, O; Doubrava, M; Egorov, I; Egorov, K; Einsweiler, K; Falou, A C; Feraudet, P; Ferrari, P; Fowler, K; Fraser, J T; French, R S; Galuska, M; Gannaway, F; Gariano, G; Gibson, M D; Gilchriese, M G D; Giugni, D; Godlewski, J; Gousakov, I; Górski, B; Hallewell, G D; Hartman, N; Hawkings, R J; Haywood, S J; Hessey, N P; Infante, S; Jackson, J N; Jones, T J; Kaplon, J; Katunin, S; Lindsay, S; Luisa, L; Massol, N; McEwan, F; McMahon, S J; Menot, C; Mistry, J; Morris, J; Muskett, D M; Nagai, K; Nichols, A; Nicholson, R; Nickerson, R B; Nielsen, S L; Nordahl, P E; Olcese, M; Parodi, M; Pérez-Gómez, F; Pernegger, H; Perrin, E; Rossi, L P; Rovani, A; Ruscino, E; Sandaker, H; Smith, A; Sopko, V; Stapnes, S; Stodulski, M; Tarrant, J; Thadome, J; Tovey, D; Turala, M; Tyndel, M; Vacek, V; van der Kraaij, E; Viehhauser, G H A; Vigeolas, E; Wells, P S; Wenig, S; Werneke, P

    2008-01-01

    This paper describes the evaporative system used to cool the silicon detector structures of the inner detector sub-detectors of the ATLAS experiment at the CERN Large Hadron Collider. The motivation for an evaporative system, its design and construction are discussed. In detail the particular requirements of the ATLAS inner detector, technical choices and the qualification and manufacture of final components are addressed. Finally results of initial operational tests are reported. Although the entire system described, the paper focuses on the on-detector aspects. Details of the evaporative cooling plant will be discussed elsewhere.

  12. An Evaporative Cooling Model for Teaching Applied Psychrometrics

    Science.gov (United States)

    Johnson, Donald M.

    2004-01-01

    Evaporative cooling systems are commonly used in controlled environment plant and animal production. These cooling systems operate based on well defined psychrometric principles. However, students often experience considerable difficulty in learning these principles when they are taught in an abstract, verbal manner. This article describes an…

  13. Experimental study of air evaporative cooling process using microporous membranes

    Directory of Open Access Journals (Sweden)

    Englart Sebastian

    2017-01-01

    Full Text Available This article describes the potential use of microporous membranes in evaporative cooling applications for air conditioning. The structure of membrane contractor and the measuring device are described. On the basis of the results of the measurements air cooling effectiveness coefficient has been determined.

  14. Mini-Membrane Evaporator for Contingency Spacesuit Cooling

    Science.gov (United States)

    Makinen, Janice V.; Bue, Grant C.; Campbell, Colin; Petty, Brian; Craft, Jesse; Lynch, William; Wilkes, Robert; Vogel, Matthew

    2015-01-01

    The next-generation Advanced Extravehicular Mobility Unit (AEMU) Portable Life Support System (PLSS) is integrating a number of new technologies to improve reliability and functionality. One of these improvements is the development of the Auxiliary Cooling Loop (ACL) for contingency crewmember cooling. The ACL is a completely redundant, independent cooling system that consists of a small evaporative cooler--the Mini Membrane Evaporator (Mini-ME), independent pump, independent feedwater assembly and independent Liquid Cooling Garment (LCG). The Mini-ME utilizes the same hollow fiber technology featured in the full-sized AEMU PLSS cooling device, the Spacesuit Water Membrane Evaporator (SWME), but Mini-ME occupies only approximately 25% of the volume of SWME, thereby providing only the necessary crewmember cooling in a contingency situation. The ACL provides a number of benefits when compared with the current EMU PLSS contingency cooling technology, which relies upon a Secondary Oxygen Vessel; contingency crewmember cooling can be provided for a longer period of time, more contingency situations can be accounted for, no reliance on a Secondary Oxygen Vessel (SOV) for contingency cooling--thereby allowing a reduction in SOV size and pressure, and the ACL can be recharged-allowing the AEMU PLSS to be reused, even after a contingency event. The first iteration of Mini-ME was developed and tested in-house. Mini-ME is currently packaged in AEMU PLSS 2.0, where it is being tested in environments and situations that are representative of potential future Extravehicular Activities (EVA's). The second iteration of Mini-ME, known as Mini-ME2, is currently being developed to offer more heat rejection capability. The development of this contingency evaporative cooling system will contribute to a more robust and comprehensive AEMU PLSS.

  15. PERSPECTIVES OF USING OF EVAPORATIVE COOLING IN REFRIGERATION ENGINEERING

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2013-08-01

    Full Text Available The concept of creation of multi-stage evaporative coolers of gases and liquids based on multi-channel monoblock polymer structures was developed. The indirect types of coolers in normal and regenerative options are used as the basic elements in them. Natural limit of the cooling in such systems is the dew point of outside air, which significantly enhances the possibilities of the evaporative cooling technology in general, and allows us to solve a number of problems of the refrigeration and air conditioning equipment with a significant reduction of energy consumption for the process. Particular attention is paid to the problem of water vapor recondensation in the transition to multi-stage evaporative coolers. The theory of joint heat and mass transfer in indirect evaporative cooling was examined. The principle of design of individual monoblocks, as well as multi-stage blocks, was developed and recommendations to the design of a new generation of evaporative coolers were made. Preliminary analysis of the possibilities of the evaporative coolers applying to the solution of problems of air conditioning was made.

  16. Mathematical Model for Direct Evaporative Space Cooling Systems ...

    African Journals Online (AJOL)

    This paper deals with the development of a simple mathematical model for experimental validation of the performance of a small evaporative cooling system in a tropical climate. It also presents the coefficient of convective heat transfer of wide range of temperatures based on existing model. Extensive experiments have ...

  17. Cooling Tower (Evaporative Cooling System) Measurement and Verification Protocol

    Energy Technology Data Exchange (ETDEWEB)

    Kurnik, Charles W. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Boyd, Brian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stoughton, Kate M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lewis, Taylor [Colorado Energy Office, Denver, CO (United States)

    2017-12-05

    This measurement and verification (M and V) protocol provides procedures for energy service companies (ESCOs) and water efficiency service companies (WESCOs) to determine water savings resulting from water conservation measures (WCMs) in energy performance contracts associated with cooling tower efficiency projects. The water savings are determined by comparing the baseline water use to the water use after the WCM has been implemented. This protocol outlines the basic structure of the M and V plan, and details the procedures to use to determine water savings.

  18. Evaporative cooling for Holstein dairy cows under grazing conditions

    Science.gov (United States)

    Valtorta, Silvia E.; Gallardo, Miriam R.

    . Twenty-four grazing Holstein cows in mid and late lactation were randomly assigned to two treatment groups: control and cooled. The trial was performed at the Experimental Dairy Unit, Rafaela Agricultural Experimental Station (INTA), Argentina. The objective was to evaluate the effects of sprinkler and fan cooling before milkings on milk production and composition. The effects of the cooling system on rectal temperature and respiration rate were also evaluated. Cooled cows showed higher milk production (1.04 l cow-1 day-1). The concentration and yield of milk fat and protein increased in response to cooling treatment. The cooling system also reduced rectal temperature and respiration rate. No effects were observed on body condition. It was concluded that evaporative cooling, which is efficient for housed animals, is also appropriate to improve yields and animal well-being under grazing systems. These results are impressive since the cooling system was utilized only before milkings, in a system where environmental control is very difficult to achieve. This trial was performed during a mild summer. The results would probably be magnified during hotter weather.

  19. ANALYSIS OF POSSIBILITIES OF EVAPORATIVE COOLING IN AUTONOMOUS AND COMBINED SYSTEMS

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2009-08-01

    Full Text Available It is described possibility of the use of the evaporative cooling as in autonomous version of execution, so in combined systems, for example, as the component of desiccant–evaporative coolers, where preliminary dehumidification of the air assures high efficiency of subsequent evaporative cooling and the depth of the cooling.

  20. Forward osmosis applied to evaporative cooling make-up water

    Energy Technology Data Exchange (ETDEWEB)

    Nicoll, Peter; Thompson, Neil; Gray, Victoria [Modern Water plc, Guildford (United Kingdom)

    2012-11-15

    Modern Water is in the process of developing a number of forward osmosis based technologies, ranging from desalination to power generation. This paper outlines the progress made to date on the development and commercial deployment of a forward osmosis based process for the production of evaporative cooling tower make-up water from impaired water sources, including seawater. Evaporative cooling requires significant amounts of good quality water to replace the water lost by evaporation, drift and blowdown. This water can be provided by conventional desalination processes or by the use of tertiary treated sewage effluent. The conventional processes are well documented and understood in terms of operation and power consumption. A new process has been successfully developed and demonstrated that provides make-up water directly, using a core platform 'forward osmosis' technology. This new technology shows significant promise in allowing various raw water sources, such as seawater, to be used directly in the forward osmosis step, thus releasing the use of scarce and valuable high grade water for other more important uses. The paper presents theoretical and operational results for the process, where it is shown that the process can produce make-up water at a fraction of the operational expenditure when compared to conventional processes, in particular regarding power consumption, which in some cases may be as low as 15 % compared to competing processes. Chemical additives to the cooling water (osmotic agent) are retained within the process, thus reducing their overall consumption. Furthermore the chemistry of the cooling water does not support the growth of Legionella pneumophila. Corrosion results are also reported. (orig.)

  1. EXPERIMENTAL APPROACH TO ASSESS EVAPORATIVE COOLING UNDER FORCED AIR FLOW

    Directory of Open Access Journals (Sweden)

    L. G. G. Rodrigues

    Full Text Available Abstract Air blast is one of the most employed industrial chilling methods. It can be enhanced, i.e., increasing heat transfer and reducing cooling time, by superficial evaporative phenomena. This work reports a methodology, including experimental setup and mathematical modelling, to quantify the air chilling enhancement by wetting the surface of the object to be chilled. A spherical metal model was covered by a cotton tissue (wet or dry and placed into a cold chamber. The effective heat transfer coefficient was determined at different temperature, air velocity, and relative humidity from time-temperature profiles into the sphere. Under the same air conditions, the effective coefficient between sphere and air was increased three-fold by moistening the cotton tissue on the sphere surface. Furthermore, comparing a dry and wet surface showed that evaporative cooling resulted in much shorter chilling times. The proposed approach was able to assess evaporative heat transfer by measuring only the time-temperature profile, and is suitable for industrial applications.

  2. Spacesuit Water Membrane Evaporator; An Enhanced Evaporative Cooling Systems for the Advanced Extravehicular Mobility Unit Portable Life Support System

    Science.gov (United States)

    Bue, Grant C.; Makinen, Janice V.; Miller, Sean.; Campbell, Colin; Lynch, Bill; Vogel, Matt; Craft, Jesse; Petty, Brian

    2014-01-01

    Spacesuit Water Membrane Evaporator - Baseline heat rejection technology for the Portable Life Support System of the Advanced EMU center dot Replaces sublimator in the current EMU center dot Contamination insensitive center dot Can work with Lithium Chloride Absorber Radiator in Spacesuit Evaporator Absorber Radiator (SEAR) to reject heat and reuse evaporated water The Spacesuit Water Membrane Evaporator (SWME) is being developed to replace the sublimator for future generation spacesuits. Water in LCVG absorbs body heat while circulating center dot Warm water pumped through SWME center dot SWME evaporates water vapor, while maintaining liquid water - Cools water center dot Cooled water is then recirculated through LCVG. center dot LCVG water lost due to evaporation (cooling) is replaced from feedwater The Independent TCV Manifold reduces design complexity and manufacturing difficulty of the SWME End Cap. center dot The offset motor for the new BPV reduces the volume profile of the SWME by laying the motor flat on the End Cap alongside the TCV.

  3. Modelling and analysis of a desiccant cooling system using the regenerative indirect evaporative cooling process

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Reinholdt, Lars O.

    2013-01-01

    This paper focuses on the numerical modeling and analysis of a Desiccant Cooling (DEC) system with regenerative indirect evaporative cooling, termed Desiccant Dewpoint Cooling (DDC) system. The DDC system includes a Desiccant Wheel (DW), Dew Point Coolers (DPCs), a heat recovery unit and a heat...... and validated by manufacturer data. The models enable calculations of the steady state operation of the system. Alternative electric and absorption chiller-based systems are also modelled for benchmarking. The systems are simulated covering the internal loads of a specified supermarket during the summer period...

  4. Laboratory study on the cooling effect of flash water evaporative cooling technology for ventilation and air-conditioning of buildings

    DEFF Research Database (Denmark)

    Fang, Lei; Yuan, Shu; Yang, Jianrong

    2016-01-01

    environments and the other simulated an air-conditioned indoor environment. The flash water evaporation cooling device was installed in the chamber that simulated indoor environment. The air from the chamber simulating outdoor environment was introduced into the cooling device and cooled by the flash water...... evaporation. Two outdoor summer climates were simulated in the study, i.e. the design summer climate of Las Vegas and the extreme summer climate of Copenhagen represented hot/dry and warm/dry climates. The results showed that the flash evaporative cooling technology, a simple and green cooling technology......This paper presents a simple cooling technology using flash water evaporation. The technology combines a water atomizer with a plate heat exchanger used for heat recovery of a ventilation system. It is mainly used to cool the ventilation airflow from outdoors and is particularly suitable to be used...

  5. Efficient Direct Evaporative Cooling in an Atom Chip Magnetic Trap

    CERN Document Server

    Farkas, Daniel M; Du, Shengwang; Anderson, Dana

    2013-01-01

    We demonstrate direct evaporative cooling of $^{87}$Rb atoms confined in a dimple trap produced by an atom chip. By changing the two chip currents and two external bias fields, we show theoretically that the trap depth can be lowered in a controlled way with no change in the trap frequencies or the value of the field at the trap center. Experimentally, we maximized the decrease in trap depth by allowing some loosening of the trap. In total, we reduced the trap depth by a factor of 20. The geometric mean of the trap frequencies was reduced by less than a factor of 6. The measured phase space density in the final two stages increased by more than two orders of magnitude, and we estimate an increase of four orders of magnitude over the entire sequence. A subsequent rf evaporative sweep of only a few megahertz produced Bose-Einstein condensates. We also produce condensates in which raising the trap bottom pushes hotter atoms into an rf "knife" operating at a fixed frequency of 5\\,MHz.

  6. Analysis of a solid desiccant cooling system with indirect evaporative cooling

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo

    and electricity. Results indicate that solar energy is utilized more efficiently than fossil fuels for supplying low regeneration temperatures. In the end, a novel technical solution aiming to make desiccant cooling systems independent of external water sources is introduced. Water desorbed from the desiccant...... dehumidifier is condensed in a closed regeneration circuit and used to run evaporative coolers. This solution enables the system to run regardless of water availability, and avoids the use of water demineralization equipment, which consumes additional water and increases operational costs and maintenance....... These benefits are achieved at the expense of higher electricity consumption, regeneration temperatures, space requirements and investment costs. The solution is analysed for the desiccant cooling system operating with dew point cooling. Mediterranean climatic conditions are considered for seasonal system...

  7. Fan and Pad Evaporative Cooling System for Greenhouses: Evaluation of a Numerical and Analytical Model

    NARCIS (Netherlands)

    Sapounas, A.; Nikita-Martzopoulou, Ch.; Bartzanas, T.; Kittas, C.

    2008-01-01

    An experimental greenhouse equipped with fan and pad evaporative cooling is analysed using two different models. The first one consists of a numerical simulation approach applying a commercial CFD code. The main aspects of evaporative cooling systems, in terms of heat and mass transfer and both the

  8. EVAPORATIVE WATER AND AIR COOLERS FOR SOLAR COOLING SYSTEMS. ANALYSIS AND PERSPECTIVES

    Directory of Open Access Journals (Sweden)

    A. Doroshenko

    2016-11-01

    Full Text Available The concept of evaporative coolers of gases and fluids on the basis of monoblock multichannel polymeric structures is presented. Different schemes of indirect evaporative coolers, in which the natural cooling limit is the dew point of the ambient air  are discussed. In such systems the cooling temperature is lower than the wet bulb temperature of the ambient air. Special attention is paid to the recondensation of water vapor for deep evaporative cooling. It is shown that for the solution of the recondensation problem it is necessary to vary the ratio of the contacting air and water flows, particularly in each stage of the multistage system. Recommendations for the deep cooling process implementation in the evaporative coolers of gases and liquids are given.

  9. The contribution of reduction in evaporative cooling to higher surface air temperatures during drought

    National Research Council Canada - National Science Library

    Yin, Dongqin; Roderick, Michael L; Leech, Guy; Sun, Fubao; Huang, Yuefei

    2014-01-01

    .... The second states that the decline in precipitation ( P ) during drought reduces the available water thereby decreasing E , and in turn the consequent reduction in evaporative cooling causes higher...

  10. Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets.

    Science.gov (United States)

    Song, Jin; Chung, Minsub; Kim, Dohyun

    2015-01-01

    We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (-5.1 °C/s) and a low freezing temperature (-14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.

  11. Humidification - Fogging and other evaporative cooling in greenhouses

    NARCIS (Netherlands)

    Nederhoff, E.M.; Weel, van P.A.

    2011-01-01

    Fogging, misting, roof sprinklers, pad-and-fan and other techniques based on water evaporation are effective tools for improving the growing conditions in a greenhouse when humidity is low. They should be used wisely though.

  12. Projected Benefits of New Residential Evaporative Cooling Systems: Progress Report #2

    Energy Technology Data Exchange (ETDEWEB)

    Kutscher, C.; Eastment, M.; Hancock, E.; Reeves, P.

    2006-10-01

    The use of conventional evaporative cooling has rapidly declined in the United States despite the fact that it has high potential for energy savings in dry climates. Evaporative systems are very competitive in terms of first cost and provide significant reductions in operating energy use, as well as peak-load reduction benefits. Significant market barriers still remain and can be addressed through improved systems integration. This report investigates the first of these approaches, exploring innovative components. The U.S. Department of Energy (DOE) Building America research teams are investigating the use of two promising new pieces of residential cooling equipment that employ evaporative cooling as a part of their system design. The OASys unit, which is a combination of direct and indirect evaporative cooling stages developed by Davis Energy Group (DEG) and manufactured by Speakman CRS, is used to ultimately provide outside air to the living space. The outdoor air provided is indirectly and directly evaporatively cooled in two stages to a condition that can be below the wet-bulb (wb) temperature of the outside air, thus outperforming a conventional single-stage direct evaporative cooler.

  13. Spacesuit Water Membrane Evaporator; An Enhanced Evaporative Cooling System for the Advanced Extravehicular Mobility Unit Portable Life Support System

    Science.gov (United States)

    Bue, Grant C.; Makinen, Janice V.; Miller, Sean; Campbell, Colin; Lynch, Bill; Vogel, Matt; Craft, Jesse; Wilkes, Robert; Kuehnel, Eric

    2014-01-01

    Development of the Advanced Extravehicular Mobility Unit (AEMU) portable life support subsystem (PLSS) is currently under way at NASA Johnson Space Center. The AEMU PLSS features a new evaporative cooling system, the Generation 4 Spacesuit Water Membrane Evaporator (Gen4 SWME). The SWME offers several advantages when compared with prior crewmember cooling technologies, including the ability to reject heat at increased atmospheric pressures, reduced loop infrastructure, and higher tolerance to fouling. Like its predecessors, Gen4 SWME provides nominal crew member and electronics cooling by flowing water through porous hollow fibers. Water vapor escapes through the hollow fiber pores, thereby cooling the liquid water that remains inside of the fibers. This cooled water is then recirculated to remove heat from the crew member and PLSS electronics. Test results from the backup cooling system which is based on a similar design and the subject of a companion paper, suggested that further volume reductions could be achieved through fiber density optimization. Testing was performed with four fiber bundle configurations ranging from 35,850 fibers to 41,180 fibers. The optimal configuration reduced the Gen4 SWME envelope volume by 15% from that of Gen3 while dramatically increasing the performance margin of the system. A rectangular block design was chosen over the Gen3 cylindrical design, for packaging configurations within the AEMU PLSS envelope. Several important innovations were made in the redesign of the backpressure valve which is used to control evaporation. A twin-port pivot concept was selected from among three low profile valve designs for superior robustness, control and packaging. The backpressure valve motor, the thermal control valve, delta pressure sensors and temperature sensors were incorporated into the manifold endcaps, also for packaging considerations. Flight-like materials including a titanium housing were used for all components. Performance testing

  14. Experimental study on the double-evaporator thermosiphon for cooling HTS (high temperature superconductor) system

    Science.gov (United States)

    Lee, Junghyun; Ko, Junseok; Kim, Youngkwon; Jeong, Sangkwon; Sung, Taehyun; Han, Younghee; Lee, Jeong-Phil; Jung, Seyong

    2009-08-01

    A cryogenic thermosiphons is an efficient heat transfer device between a cryocooler and a thermal load that is to be cooled. This paper presents an idea of thermosiphon which contains two vertically-separated evaporators. This unique configuration of the thermosiphon is suitable for the purpose of cooling simultaneously two superconducting bearings of the HTS (high temperature superconducting) flywheel system at the same temperature. A so-called double-evaporator thermosiphon was designed, fabricated and tested using nitrogen as the working fluid under sub-atmospheric pressure condition. The interior thermal condition of the double-evaporator thermosiphon was examined in detail during its cool-down process according to the internal thermal states. The double-evaporator thermosiphon has operated successfully at steady-state operation under sub-atmospheric pressure. At the heat flow of 10.6 W, the total temperature difference of the thermosiphon was only 1.59 K and the temperature difference between the evaporators was 0.64 K. The temperature difference of two evaporators is attributed to the conductive thermal resistance of the adiabatic section between the evaporators. The method to reduce this temperature difference has been investigated and presented in this paper. The proper area selection of condenser, evaporator 1, and evaporator 2 was studied by using thermal resistance model to optimize the performance of a thermosiphon. The superior heat transfer characteristic of the double-evaporator thermosiphon without involving any cryogenic pump can be a great potential advantage for cooling HTS bulk modules that are separated vertically.

  15. Design and Fabrication of a Passive Evaporative Cooling System for Fruits and Vegetables Storage

    Directory of Open Access Journals (Sweden)

    M. O. Sunmonu

    2012-12-01

    Full Text Available A multipurpose passive evaporative cooler was designed, constructed and its performance evaluated by determining the adiabatic efficiency. The multi-purpose passive evaporative cooling system consists of three compartments whose outer and inner cooling chambers were made of galvanize steel. The interspace was filled with sandy loam. The cold storage system for fruits and vegetables was based on the water cooling system to cool the storage chamber. Water is supplied from the storage tank to a pipe with a gate valve attached to this pipe. As the valve is opened, water flows through the distribution pipe networks placed over the soil allow in a constant flow of water through into soil. The water leaves the system through the outlets created underneath the housing. This process is continuous; as the water moves out, it carries along the heat present inside the cooling chamber hence lowering the temperature and at the same time increasing the relative humidity in the storage chamber. During the test period with fresh bananas, the average temperatures of 24.5°C and 28.8°C were obtained; for the multi-purpose evaporative cooler and the ambient respectively. Also average relative humidity of 8-8.87% and 69.41% were obtained for the multi-purpose evaporative cooler and the ambient respectively. The cooling efficiency of the evaporative cooler was 55%.

  16. Analysis of the evaporative towers cooling system of a coal-fired power plant

    Directory of Open Access Journals (Sweden)

    Laković Mirjana S.

    2012-01-01

    Full Text Available The paper presents a theoretical analysis of the cooling system of a 110 MW coal-fired power plant located in central Serbia, where eight evaporative towers cool down the plant. An updated research on the evaporative tower cooling system has been carried out to show the theoretical analysis of the tower heat and mass balance, taking into account the sensible and latent heat exchanged during the processes which occur inside these towers. Power plants which are using wet cooling towers for cooling condenser cooling water have higher design temperature of cooling water, thus the designed condensing pressure is higher compared to plants with a once-through cooling system. Daily and seasonal changes further deteriorate energy efficiency of these plants, so it can be concluded that these plants have up to 5% less efficiency compared to systems with once-through cooling. The whole analysis permitted to evaluate the optimal conditions, as far as the operation of the towers is concerned, and to suggest an improvement of the plant. Since plant energy efficiency improvement has become a quite common issue today, the evaluation of the cooling system operation was conducted under the hypothesis of an increase in the plant overall energy efficiency due to low cost improvement in cooling tower system.

  17. Design of evaporative-cooling roof for decreasing air temperatures in buildings in the humid tropics

    Science.gov (United States)

    Kindangen, Jefrey I.; Umboh, Markus K.

    2017-03-01

    This subject points to assess the benefits of the evaporative-cooling roof, particularly for buildings with corrugated zinc roofs. In Manado, many buildings have roofed with corrugated zinc sheets; because this material is truly practical, easy and economical application. In general, to achieve thermal comfort in buildings in a humid tropical climate, people applying cross ventilation to cool the air in the room and avoid overheating. Cross ventilation is a very popular path to achieve thermal comfort; yet, at that place are other techniques that allow reducing the problem of excessive high temperature in the room in the constructions. This study emphasizes applications of the evaporative-cooling roof. Spraying water on the surface of the ceiling has been executed on the test cell and the reuse of water after being sprayed and cooled once more by applying a heat exchanger. Initial results indicate a reliable design and successfully meet the target as an effective evaporative-cooling roof technique. Application of water spraying automatic and cooling water installations can work optimally and can be an optimal model for the cooling roof as one of the green technologies. The role of heat exchangers can lower the temperature of the water from spraying the surface of the ceiling, which has become a hot, down an average of 0.77° C. The mass flow rate of the cooling water is approximately 1.106 kg/h and the rate of heat flow is around 515 Watt, depend on the site.

  18. The impact of humidity on evaporative cooling in small desert birds exposed to high air temperatures.

    Science.gov (United States)

    Gerson, Alexander R; Smith, Eric Krabbe; Smit, Ben; McKechnie, Andrew E; Wolf, Blair O

    2014-01-01

    Environmental temperatures that exceed body temperature (Tb) force endothermic animals to rely solely on evaporative cooling to dissipate heat. However, evaporative heat dissipation can be drastically reduced by environmental humidity, imposing a thermoregulatory challenge. The goal of this study was to investigate the effects of humidity on the thermoregulation of desert birds and to compare the sensitivity of cutaneous and respiratory evaporation to reduced vapor density gradients. Rates of evaporative water loss, metabolic rate, and Tb were measured in birds exposed to humidities ranging from ∼2 to 30 g H2O m(-3) (0%-100% relative humidity at 30°C) at air temperatures between 44° and 56°C. In sociable weavers, a species that dissipates heat primarily through panting, rates of evaporative water loss were inhibited by as much as 36% by high humidity at 48°C, and these birds showed a high degree of hyperthermia. At lower temperatures (40°-44°C), evaporative water loss was largely unaffected by humidity in this species. In Namaqua doves, which primarily use cutaneous evaporation, increasing humidity reduced rates of evaporative water loss, but overall rates of water loss were lower than those observed in sociable weavers. Our data suggest that cutaneous evaporation is more efficient than panting, requiring less water to maintain Tb at a given temperature, but panting appears less sensitive to humidity over the air temperature range investigated here.

  19. Dew Point Evaporative Comfort Cooling: Report and Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Dean, J.; Herrmann, L.; Kozubal, E.; Geiger, J.; Eastment, M.; Slayzak, S.

    2012-11-01

    The project objective was to demonstrate the capabilities of the high-performance multi-staged IEC technology and its ability to enhance energy efficiency and interior comfort in dry climates, while substantially reducing electric-peak demand. The project was designed to test 24 cooling units in five commercial building types at Fort Carson Army Base in Colorado Springs, Colorado.

  20. Feasibility and economic evaluation of low-cost evaporative cooling ...

    African Journals Online (AJOL)

    A fixed operating air flow rate of 4.3 kg- 1 was used to evaluate cooling performance and energy efficiency ratio of the cooler. The results showed that the indoor dry bulb temperature significantly (P < 0.001) drops parallel with a significant (P < 0.001) rise in relative humidity during storage. The energy efficiency ratio ...

  1. Feasibility Study Of Maisotsenko Indirect Evaporative Air Cooling Cycle In Iran

    Directory of Open Access Journals (Sweden)

    Rezaee Vahid

    2015-06-01

    Full Text Available This paper presents energy and exergy analysis of air cooling cycle based on novel Maisotsenko indirect evaporative cooling cycle. Maisotsenko cycle (M-cycle provides desired cooling condition above the dew point and below the wet bulb temperature. In this study, based on average annual temperature, The Iran area is segmented into eleven climates. In energy analysis, wet-bulb and dew point effectiveness, cooling capacity rate and in exergy analysis, exergy input rate, exergy destruction rate, exergy loss, exergy efficiency, exergetic COP and entropy generation rate for Iran's weather conditions in the indicated climates are calculated. Moreover, a feasibility study based on water evaporation rate and Maisotsenko cycle was presented. Energy and exergy analysis results show that the fifth, sixth, seventh and eighth climates are quite compatible and Rasht, Sari, Ramsar and Ardabile cities are irreconcilable with the Maisotsenko cycle.

  2. Thin-Film Evaporative Cooling for Side-Pumped Laser

    Science.gov (United States)

    Stewart, Brian K. (Inventor)

    2010-01-01

    A system and method are provided for cooling a crystal rod of a side-pumped laser. A transparent housing receives the crystal rod therethrough so that an annular gap is defined between the housing and the radial surface of the crystal rod. A fluid coolant is injected into the annular gap such the annular gap is partially filled with the fluid coolant while the radial surface of the crystal rod is wetted as a thin film all along the axial length thereof.

  3. Investigation Of Combined Indirect Evaporative Ducted Cooling Equipment Efficiency In Historical Building In Temperate Climate

    Directory of Open Access Journals (Sweden)

    Brahmanis Artūrs

    2014-10-01

    Full Text Available The present study is devoted to the evaluation of efficiency of the combined indirect evaporative - compressor water cooling system under various outdoor air humidity conditions of temperate climate. This is a building- based study, which represents the results of the analytical research, conducted in the recently restored 19th century historical building, The Art Museum Riga Bourse.

  4. Experimental study on an innovative enthalpy recovery technology based on indirect flash evaporative cooling

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Yuan, Shu; Fang, Lei

    2018-01-01

    An indirect flash evaporative cooling enthalpy recovery technology used for building ventilation was proposed based on counter flow plate heat exchanger combing with ultrasonic atomizer. The technology is aimed at enhancing enthalpy recover efficiency and preventing contaminant transfer of heat r...

  5. Numerical and Experimental Study of Fan and Pad Evaporative Cooling System in a Greenhouse with Tomato Crop

    NARCIS (Netherlands)

    Sapounas, A.; Nikita-Martzopoulou, Ch.; Martzopoulos, G.

    2008-01-01

    An experimental greenhouse equipped with fan and pad evaporative cooling is simulated numerically using a commercial CFD code. The main aspects of evaporative cooling systems, in terms of heat and mass transfer and both the external and internal climatic conditions were integrated to set up the

  6. Solar Multi-stage Refrigeration Systems on the Basis of Absorber with the Internal Evaporative Cooling

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2015-08-01

    Full Text Available In the article, the developed schematics are presented for the alternative refrigeration systems and air-conditioning systems, based on the use of absorbing cycle and solar energy for the regeneration of absorbent solution. Multi-stage principle of construction of drying and cool contours of solar systems is used with growth of concentration of absorbent on the stages of cooler. An absorber with internal evaporative cooling, allowing to remove the separate evaporated cooler, usually included after the absorber of the proper stage, is developed. Heat-mass-transfer apparatus of film-type, entering in the complement of drying and cool contours compatible and executed on the basis of multichannel compositions from polymeric materials. The preliminary comparative analysis of possibilities of the solar refrigeration systems and air-conditioning systems is executed.

  7. Reduced Volume Prototype Spacesuit Water Membrane Evaporator; A Next-Generation Evaporative Cooling System for the Advanced Extravehicular Mobility Unit Portable Life Support System

    Science.gov (United States)

    Makinen, Janice V.; Anchondo, Ian; Bue, Grant C.; Campbell, Colin; Colunga, Aaron

    2013-01-01

    Development of the Advanced Extravehicular Mobility Unit (AEMU) portable life support subsystem (PLSS) is currently under way at NASA Johnson Space Center. The AEMU PLSS features a new evaporative cooling system, the reduced volume prototype (RVP) spacesuit water membrane evaporator (SWME). The RVP SWME is the third generation of hollow fiber SWME hardware. Like its predecessors, RVP SWME provides nominal crew member and electronics cooling by flowing water through porous hollow fibers. Water vapor escapes through the hollow fiber pores, thereby cooling the liquid water that remains inside of the fibers. This cooled water is then recirculated to remove heat from the crew member and PLSS electronics. Major design improvements, including a 36% reduction in volume, reduced weight, and a more flight-like backpressure valve, facilitate the packaging of RVP SWME in the AEMU PLSS envelope. The development of these evaporative cooling systems will contribute to a more robust and comprehensive AEMU PLSS.

  8. Sub-ambient non-evaporative fluid cooling with the sky

    Science.gov (United States)

    Goldstein, Eli A.; Raman, Aaswath P.; Fan, Shanhui

    2017-09-01

    Cooling systems consume 15% of electricity generated globally and account for 10% of global greenhouse gas emissions. With demand for cooling expected to grow tenfold by 2050, improving the efficiency of cooling systems is a critical part of the twenty-first-century energy challenge. Building upon recent demonstrations of daytime radiative sky cooling, here we demonstrate fluid cooling panels that harness radiative sky cooling to cool fluids below the air temperature with zero evaporative losses, and use almost no electricity. Over three days of testing, we show that the panels cool water up to 5 ∘C below the ambient air temperature at water flow rates of 0.2 l min‑1 m‑2, corresponding to an effective heat rejection flux of up to 70 W m‑2. We further show through modelling that, when integrated on the condenser side of the cooling system of a two-storey office building in a hot dry climate (Las Vegas, USA), electricity consumption for cooling during the summer could be reduced by 21% (14.3 MWh).

  9. Evaporators

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard

    1996-01-01

    Type of evaporators. Regulation. Thermal dimensioning. Determination of pressure loss and heat transfer coefficients.......Type of evaporators. Regulation. Thermal dimensioning. Determination of pressure loss and heat transfer coefficients....

  10. Study on dew point evaporative cooling system with counter-flow configuration

    KAUST Repository

    Lin, J.

    2015-12-18

    Dew point evaporative cooling has great potential as a disruptive process for sensible cooling of air below its entering wet bulb temperature. This paper presents an improved mathematical model for a single-stage dew point evaporative cooler in a counter-flow configuration. Longitudinal heat conduction and mass diffusion of the air streams, channel plate and water film, as well as the temperature difference between the plate and water film, are accounted for in the model. Predictions of the product air temperature are validated using three sets of experimental data within a discrepancy of 4%. The cooler’s heat and mass transfer process is analyzed in terms of its cooling capacity intensity, water evaporation intensity, and overall heat transfer coefficient along the channel. Parametric studies are conducted at different geometric and operating conditions. For the conditions evaluated, the study reveals that (1) the saturation point of the working air occurs at a fixed point regardless of the inlet air conditions, and it is mainly influenced by the working air ratio and channel height; (2) the intensity of the water evaporation approaches a minimum at 0.2 to 0.3m from the entrance; (3) the wet channel can be separated into two zones, and the overall heat transfer coefficient is above 100W/(m2·K) after the temperature of water film becomes higher than the working air temperature.

  11. Preservation of Postharvest Quality of Leafy Amaranth (Amaranthus spp. Vegetables Using Evaporative Cooling

    Directory of Open Access Journals (Sweden)

    Jane Ambuko

    2017-01-01

    Full Text Available Leafy vegetables are very highly perishable and must be utilized immediately after harvest. Their fast deterioration is attributed to various biological and environmental factors with temperature playing a central role. Evaporative cooling is a low-cost temporary storage technology that offers smallholder vegetable farmers an alternative to expensive cold rooms. The present study sought to determine the effectiveness of evaporative cooling using zero energy brick cooler (ZEBC and evaporative charcoal cooler (ECC, to preserve the postharvest quality of leafy amaranth vegetables. Freshly harvested vegetables were separated into bundles weighing 300 grams and stored under ZEBC, ECC, and ambient room conditions (control. Real time changes in temperature and relative humidity (RH as well as changes in quality attributes (physiological weight loss (PWL, wilting index, hue angle, and vitamin C were determined during the storage period. The temperature difference between the ZEBC and ECC versus the ambient air ranged between 4 and 10°C. Significantly higher RH (80–100% was recorded in both evaporative cooling chambers. At the end of storage, higher PWL (47.6% was recorded at ambient room conditions compared to 10.5 and 6.7% under ZEBC and ECC, respectively. A rapid decline in vitamin C (51% was reported in vegetables stored at ambient room conditions. Overall, there was better vegetable quality preservation under ECC and ZEBC.

  12. Evaporative cooling system for storage of fruits and vegetables - a review.

    Science.gov (United States)

    Lal Basediya, Amrat; Samuel, D V K; Beera, Vimala

    2013-06-01

    Horticultural produce are stored at lower temperature because of their highly perishable nature. There are many methods to cool the environment. Hence, preserving these types of foods in their fresh form demands that the chemical, bio-chemical and physiological changes are restricted to a minimum by close control of space temperature and humidity. The high cost involved in developing cold storage or controlled atmosphere storage is a pressing problem in several developing countries. Evaporative cooling is a well-known system to be an efficient and economical means for reducing the temperature and increasing the relative humidity in an enclosure and this effect has been extensively tried for increasing the shelf life of horticultural produce in some tropical and subtropical countries. In this review paper, basic concept and principle, methods of evaporative cooling and their application for the preservation of fruits and vegetables and economy are also reported. Thus, the evaporative cooler has prospect for use for short term preservation of vegetables and fruits soon after harvest. Zero energy cooling system could be used effectively for short-duration storage of fruits and vegetables even in hilly region. It not only reduces the storage temperature but also increases the relative humidity of the storage which is essential for maintaining the freshness of the commodities.

  13. Modeling of a regenerative indirect evaporative cooler for a desiccant cooling system

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Reinholdt, Lars O.

    This paper presents a numerical study of a regenerative indirect evaporative cooler, the so-called Dew Point Cooler (DPC), which is part of a Desiccant Cooling system that may both dehumidify and cool humid air. The DPC model is based on first principles using a 1D finite volume scheme...... and determines the steady state working conditions for the component. A sensitivity analysis of the DPC performance is carried out based on the air inlet conditions, air flow rate and recirculation fraction. A recirculation fraction around 0.3 maximizes the DPC net cooling capacity. The supply temperature...... is found to be mostly affected by the inlet humidity ratio. Manufacturer data are used to tune the model. The tuned DPC model is characterized by an area effectiveness coefficient which is kept constant at 0.55. The cooling capacity and water consumption estimated by the tuned model deviate within 3% and 8...

  14. Mini-channel evaporator/heat pipe assembly for a chip cooling vapor compression refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Guilherme B.; Barbosa, Jader R. Jr.; Prata, Alvaro T. [Polo - Research Laboratories for Emerging Technologies in Cooling and Thermophysics, Department of Mechanical Engineering, Campus Universitario, Trindade, Federal University of Santa Catarina, Florianopolis, SC 88040900 (Brazil)

    2010-11-15

    We investigate a novel evaporator design for a small-scale refrigeration system whose function is to assist the existing heat pipe technology currently used in chip cooling of portable computers. A heat transfer model for the evaporator/heat pipe assembly was devised specifically for sizing the evaporator in order to keep the chip surface temperature below a certain value. A prototype was tested with R-600a at saturation temperatures of 45 and 55 C, mass flow rates between 0.5 and 1.5 kg h{sup -1} and heat transfer rates between 30 and 60 W. The experimental results demonstrated that the average refrigerant-side heat transfer coefficient is more sensitive to a change in the refrigerant mass flux than to changes in the saturation temperature and heat transfer rate. The agreement between the calculated heat transfer coefficient and the data was within {+-}10% for the conditions evaluated. (author)

  15. Exergoeconomic optimization of coaxial tube evaporators for cooling of high pressure gaseous hydrogen during vehicle fuelling

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Rothuizen, Erasmus Damgaard; Markussen, Wiebke Brix

    2014-01-01

    Gaseous hydrogen as an automotive fuel is reaching the point of commercial introduction. Development of hydrogen fuelling stations considering an acceptable fuelling time by cooling the hydrogen to -40 C has started. This paper presents a design study of coaxial tube ammonia evaporators for three...... different concepts of hydrogen cooling, one onestage and two two-stage processes. An exergoeconomic optimization is imposed to all three concepts to minimize the total cost. A numerical heat transfer model is developed in Engineer Equation Solver, using heat transfer and pressure drop correlations from...

  16. Thermal design of lithium bromide-water solution vapor absorption cooling system for indirect evaporative cooling for IT pod

    Science.gov (United States)

    Sawant, Digvijay Ramkrishna

    Nowadays with increase use of internet, mobile there is increase in heat which ultimately increases the efficient cooling system of server room or IT POD. Use of traditional ways of cooling system has ultimately increased CO2 emission and depletion of CFC's are serious environmental issues which led scientific people to improve cooling techniques and eliminate use of CFC's. To reduce dependency on fossil fuels and 4environmental friendly system needed to be design. For being utilizing low grade energy source such as solar collector and reducing dependency on fossil fuel vapour absorption cooling system has shown a great driving force in today's refrigeration systems. This LiBr-water aabsorption cooling consists of five heat exchanger namely: Evaporator, Absorber, Solution Heat Exchanger, Generator, Condenser. The thermal design was done for a load of 23 kW and the procedure was described in the thesis. There are 120 servers in the IT POD emitting 196 W of heat each on full load and some of the heat was generated by the computer placed inside the IT POD. A detailed procedure has been discussed. A excel spreadsheet was to prepared with varying tube sizes to see the effect on flows and ultimately overall heat transfer coefficient.

  17. Performance evaluation of three different types of local evaporative cooling pads in greenhouses in Sudan

    OpenAIRE

    Ahmed, Egbal Mohammed; Abaas, Osama; Ahmed, Mohammed; Ismail, Mohd Rodzi

    2010-01-01

    This study was conducted in Date Palm Technology Company Limited, Shambat, Khartoum State. To evaluate performance of three types of evaporative cooling pads for greenhouses (celdek pads, straw pads and sliced wood pads), as compared to the conditions outside the greenhouses (control), for pads. Performance evaluation includes environmental parameters (temperature and relative humidity at 8 am, 1 pm and 6 pm) and crop parameters (length and stem diameter, leaves number and width, fruit length...

  18. Fluorocarbon evaporative cooling developments for the ATLAS pixel and semiconductor tracking detectors

    CERN Document Server

    Anderssen, E; Berry, S; Bonneau, P; Bosteels, Michel; Bouvier, P; Cragg, D; English, R; Godlewski, J; Górski, B; Grohmann, S; Hallewell, G D; Hayler, T; Ilie, S; Jones, T; Kadlec, J; Lindsay, S; Miller, W; Niinikoski, T O; Olcese, M; Olszowska, J; Payne, B; Pilling, A; Perrin, E; Sandaker, H; Seytre, J F; Thadome, J; Vacek, V

    1999-01-01

    Heat transfer coefficients 2-5.103 Wm-2K-1 have been measured in a 3.6 mm I.D. heated tube dissipating 100 Watts - close to the full equivalent power (~110 W) of a barrel SCT detector "stave" - over a range of power dissipations and mass flows in the above fluids. Aspects of full-scale evaporative cooling circulator design for the ATLAS experiment are discussed, together with plans for future development.

  19. Flow Boiling Heat Transfer in Microchannel Cold Plate Evaporators for Electronics Cooling

    OpenAIRE

    Bertsch, Stefan S.; Groll, Eckhard A; Garimella, Suresh V.

    2008-01-01

    The local two-phase heat transfer coefficient is a critical parameter in the design of microchannel cold plate evaporators used in applications such as electronics cooling systems. Only a few past studies on microchannels have investigated the heat transfer characteristics over the entire vapor quality range and conflicting trends have been reported even in these studies. Therefore, the present study focuses on the investigation of the local flow boiling heat transfer coefficient at different...

  20. A dynamic experimental study on the evaporative cooling performance of porous building materials

    Science.gov (United States)

    Zhang, Yu; Zhang, Lei; Meng, Qinglin; Feng, Yanshan; Chen, Yuanrui

    2017-08-01

    Conventional outdoor dynamic and indoor steady-state experiments have certain limitations in regard to investigating the evaporative cooling performance of porous building materials. The present study investigated the evaporative cooling performance of a porous building material using a special wind tunnel apparatus. First, the composition and control principles of the wind tunnel environment control system were elucidated. Then, the meteorological environment on a typical summer day in Guangzhou was reproduced in the wind tunnel and the evaporation process and thermal parameters of specimens composed of a porous building material were continuously measured. Finally, the experimental results were analysed to evaluate the accuracy of the wind tunnel environment control system, the heat budget of the external surface of the specimens and the total thermal resistance of the specimens and its uncertainty. The analysis results indicated that the normalized root-mean-square error between the measured value of each environmental parameter in the wind tunnel test section and the corresponding value input into the environment control system was thermal resistance of the wet specimen was approximately doubled, indicating that the evaporation process of the porous building material could significantly improve the thermal insulation performance of the specimen.

  1. CO$_2$ evaporative cooling: The future for tracking detector thermal management

    CERN Document Server

    AUTHOR|(CDS)2051454; Daguin, Jerome; Petagna, Paolo; Postema, Willem Johannes; Bart Verlaat; Lukasz Zwalinski

    2016-01-01

    In the last few years, CO$_2$ evaporative cooling has been one of the favourite technologies chosen for the thermal management of tracking detectors at LHC. ATLAS Insertable B-Layer and CMS Pixel phase 1 upgrade have adopted it and their systems are now operational or under commissioning. The CERN PH-DT team is now merging the lessons learnt on these two systems in order to prepare the design and construction of the cooling systems for the new Upstream Tracker and the Velo upgrade in LHCb, due by 2018. Meanwhile, the preliminary design of the ATLAS and CMS full tracker upgrades is started, and both concepts heavily rely on CO$_2$ evaporative cooling. This paper highlights the performances of the systems now in operation and the challenges to overcome in order to scale them up to the requirements of the future generations of trackers. In particular, it focuses on the conceptual design of a new cooling system suited for the large phase 2 upgrade programmes, which will be validated with the con...

  2. Evaporative CO2 microchannel cooling for the LHCb VELO pixel upgrade

    Science.gov (United States)

    de Aguiar Francisco, O. A.; Buytaert, J.; Collins, P.; Dumps, R.; John, M.; Mapelli, A.; Romagnoli, G.

    2015-05-01

    The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the system will be provided by evaporative CO2 circulating in microchannels embedded within thin silicon plates. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASICs and sensors, the radiation hardness of CO2, and very low contribution to the material budget. Although microchannel cooling is gaining considerable attention for applications related to microelectronics, it is still a novel technology for particle physics experiments, in particular when combined with evaporative CO2 cooling. The R&D effort for LHCb is focused on the design and layout of the channels together with a fluidic connector and its attachment which must withstand pressures up to 170 bar. Even distribution of the coolant is ensured by means of the use of restrictions implemented before the entrance to a race track like layout of the main cooling channels. The coolant flow and pressure drop have been simulated as well as the thermal performance of the device. This proceeding describes the design and optimization of the cooling system for LHCb and the latest prototyping results.

  3. CO{sub 2} evaporative cooling: The future for tracking detector thermal management

    Energy Technology Data Exchange (ETDEWEB)

    Tropea, P., E-mail: paola.tropea@cern.ch [CERN, Geneva (Switzerland); Daguin, J.; Petagna, P.; Postema, H. [CERN, Geneva (Switzerland); Verlaat, B. [CERN, Geneva (Switzerland); Nikhef, Amsterdam (Netherlands); Zwalinski, L. [CERN, Geneva (Switzerland)

    2016-07-11

    In the last few years, CO{sub 2} evaporative cooling has been one of the favourite technologies chosen for the thermal management of tracking detectors at LHC. ATLAS Insertable B-Layer and CMS Pixel phase 1 upgrade have adopted it and their systems are now operational or under commissioning. The CERN PH-DT team is now merging the lessons learnt on these two systems in order to prepare the design and construction of the cooling systems for the new Upstream Tracker and the Velo upgrade in LHCb, due by 2018. Meanwhile, the preliminary design of the ATLAS and CMS full tracker upgrades is started, and both concepts heavily rely on CO{sub 2} evaporative cooling. This paper highlights the performances of the systems now in operation and the challenges to overcome in order to scale them up to the requirements of the future generations of trackers. In particular, it focuses on the conceptual design of a new cooling system suited for the large phase 2 upgrade programmes, which will be validated with the construction of a common prototype in the next years.

  4. Thermo-dynamical measurements for ATLAS Inner Detector (evaporative cooling system)

    CERN Document Server

    Bitadze, Alexander; Buttar, Craig

    During the construction, installation and initial operation of the Evaporative Cooling System for the ATLAS Inner Detector SCT Barrel Sub-detector, some performance characteristics were observed to be inconsistent with the original design specifications, therefore the assumptions made in the ATLAS Inner Detector TDR were revisited. The main concern arose because of unexpected pressure drops in the piping system from the end of the detector structure to the distribution racks. The author of this theses made a series of measurements of these pressure drops and the thermal behavior of SCT-Barrel cooling Stave. Tests were performed on the installed detector in the pit, and using a specially assembled full scale replica in the SR1 laboratory at CERN. This test setup has been used to perform extensive tests of the cooling performance of the system including measurements of pressure drops in different parts of system, studies of the thermal profile along the stave pipe for different running conditions / parameters a...

  5. Modeling of the Evaporative Cooling of Running-Down Liquid Films in the Slit Channel of the Spraying Device of a Cooling Tower

    Science.gov (United States)

    Dashkov, G. V.; Malenko, G. L.; Solodukhin, A. D.; Tyutyuma, V. D.

    2014-11-01

    This paper presents the results of computational modeling of the nonstationary evaporative cooling of a liquid film running down a vertical surface cooled by a turbulent vapor-air counterflow. The heat and mass transfer problem has been formulated in conjugate form. The calculation data on the total heat flow density at the interface for various instants of time are given.

  6. The development of evaporative liquid film model for analysis of passive containment cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hong June; Hwang, Young Dong; Kim, Hee Cheol; Kim, Young In; Chang, Moon Hee

    2000-07-01

    An analytical model was developed to simulate behavior of the liquid film formed on the outside surface of the steel containment vessel of PCCS including the ellipsoidal dome and the vertical wall. The model was coupled with CFX code using the user subroutines provided by the code, and a series of numerical calculations were performed to evaluate the evaporative heat transfer coefficient at the interface. Numerical results for Sherwood number and evaporative heat transfer coefficient were compared with the experimental data. The results were in good agreement with the experimental data. The calculated liquid film thickness showed good agreement with that of Sun except an upper portion of the channel. The model was applied to the full scale of PCCS to investigate the effects of dome and chimney on the evaporation rate. The results showed that the heat transfer coefficient in the dome region, where the flow cross-sectional area decreases and the swirling occurs, was lower than that of the vertical annulus region. The calculated evaporative heat transfer coefficient was about 20 times larger than that of the dry cooling. Sensitivity studies on the gap size and the wall temperature were also performed to figure out their effects on the heat transfer coefficient and inlet air average velocity. Through the analysis of the dryout point, the minimum liquid film flow rate to cover the entire surface of the vessel was estimated.

  7. Unsteady-state analysis of a counter-flow dew point evaporative cooling system

    KAUST Repository

    Lin, J.

    2016-07-19

    Understanding the dynamic behavior of the dew point evaporative cooler is crucial in achieving efficient cooling for real applications. This paper details the development of a transient model for a counter-flow dew point evaporative cooling system. The transient model approaching steady conditions agreed well with the steady state model. Additionally, it is able to accurately predict the experimental data within 4.3% discrepancy. The transient responses of the cooling system were investigated under different inlet air conditions. Temporal temperature and humidity profiles were analyzed for different transient and step responses. The key findings from this study include: (1) the response trend and settling time is markedly dependent on the inlet air temperature, humidity and velocity; (2) the settling time of the transient response ranges from 50 s to 300 s when the system operates under different inlet conditions; and (3) the average transient wet bulb effectiveness (1.00–1.06) of the system is observed to be higher than the steady state wet bulb effectiveness (1.01) for our range of study. © 2016 Elsevier Ltd

  8. Effectiveness of indirect evaporative cooling and thermal mass in a hot arid climate

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Eduardo [Programa de Pos-Graduacao em Tecnologia/Programa de Pos-Graduacao em Engenharia Civil, Departamento de Construcao Civil, Universidade Tecnologica Federal do Parana - UTFPR, Av. Sete de Setembro, 3165. Curitiba PR, CEP. 80230-901 (Brazil); Gonzalez Cruz, Eduardo [Instituto de Investigaciones de la Facultad de Arquitectura y Diseno (IFAD), Universidad del Zulia, Nucleo Tecnico de LUZ, Av. Goajira (16) con Calle 67, Maracaibo, CP 4011-A-526 (Venezuela); Givoni, Baruch [Department of Architecture, School of Arts and Architecture, UCLA, Los Angeles CA, USA, and Ben Gurion University (Israel)

    2010-06-15

    In this paper, we compare results of a long-term temperature monitoring in a building with high thermal mass to indoor temperature predictions of a second building that uses an indirect evaporative cooling system as a means of passive cooling (Vivienda Bioclimatica Prototipo -VBP-1), for the climatic conditions of Sde Boqer, Negev region of Israel (local latitude 30 52'N, longitude 34 46'E, approximately 480 m above sea level). The high-mass building was monitored from January through September 2006 and belongs to a student dormitory complex located at the Sde Boqer Campus of Ben-Gurion University. VBP-1 was designed and built in Maracaibo, Venezuela (latitude 10 34'N, longitude 71 44'W, elevation 66 m above sea level) and had its indoor air temperatures, below and above a shaded roof pond, as well as the pond temperature monitored from February to September 2006. Formulas were developed for the VBP-1, based on part of the whole monitoring period, which represent the measured daily indoor maximum, average and minimum temperatures. The formulas were then validated against measurements taken independently in different time periods. The developed formulas were here used for estimating the building's thermal and energy performance at the climate of Sde Boqer, allowing a comparison of two different strategies: indirect evaporative cooling and the use of thermal mass. (author)

  9. Energy evaluation of an evaporative cooling system using water driven ejector

    Directory of Open Access Journals (Sweden)

    Cíntia Carla Melgaço de Oliveira

    2014-06-01

    Full Text Available The search for efficient and accessible cooling systems has increased worldwide. This study aims to build and evaluate an evaporative cooling system using a water driven ejector, allowing it to be installed in places with plenty of water. The system was investigated varying the flow rate and temperature of the circulating water, temperature of the replacement water, and coefficient of performance. The best vacuum obtained was 8.5 kPa at nominal operating conditions of 4.1 ± 0.1 m³/h and 5 ± 0.5 ºC for the circulating water reaching the temperature of 9.7 ± 0.5 ºC. The pulse-like disturbance generated by replacing the cooling water at different periods of times did not result in significant affect vacuum destabilization and the temperature rise in the cooling tank. The coefficient of performance of the system at the highest thermal power of 92.27 W was 0.077, which was underestimated due to possible problems related to pump efficiency. The system evaluated under the conditions proposed can be very efficient for cooling fluids at higher temperatures, and it can be complementary to main refrigeration systems.

  10. Experimental performance and parametric analysis of heat pipe heat exchanger for air conditioning application integrated with evaporative cooling

    Science.gov (United States)

    Jadhav, Tushar S.; Lele, Mandar M.

    2017-11-01

    The experimental performance of different heat pipe heat exchanger (HPHX) configurations using distilled water as the working fluid is reported in the present study. The three HPHX configurations in the present investigation include HPHX with single wick structure (HPHX 1), HPHX with composite wick structure (HPHX 2) and hybrid HPHX (HPHX 3) which is the combination of HPHX 1 and HPHX 2. The parameters considered for the parametric analysis of HPHX in all the three configurations are outdoor air dry bulb temperature entering the evaporator section of HPHX (OADBT), return air dry bulb temperature entering the condenser section of HPHX (RADBT), outdoor air velocity (Ve) and return air velocity (Vc). The OADBT is varied between 40 and 24 °C and the outdoor & return air velocities between 0.6 and 2.4 m/s. The parametric analysis of HPHX without evaporative cooling is studied for RADBT = 24 °C whereas RADBT is maintained at 20 °C for the parametric analysis of HPHX integrated with evaporative cooling. In comparison with HPHX without evaporative cooling, the performance of HPHX with evaporative cooling is enhanced by 17% for single wick structure (HPHX 1), 47% for composite wick structure (HPHX 2) and 59% for hybrid HPHX (HPHX 3) for OADBT = 40 °C and at Ve = Vc of 0.6 m/s. The results of the experimental analysis highlights the benefits of HPHX integrated with evaporative cooling for achieving significant energy savings in air conditioning application.

  11. Evaporative CO2 cooling using microchannels etched in silicon for the future LHCb vertex detector

    CERN Document Server

    Nomerotski, A.; Collins, P.; Dumps, R.; Greening, E.; John, M.; Mapelli, A.; Leflat, A.; Li, Y.; Romagnoli, G.; Verlaat, B.

    2013-01-01

    The extreme radiation dose received by vertex detectors at the Large Hadron Collider dictates stringent requirements on their cooling systems. To be robust against radiation damage, sensors should be maintained below -20 degree C and at the same time, the considerable heat load generated in the readout chips and the sensors must be removed. Evaporative CO2 cooling using microchannels etched in a silicon plane in thermal contact with the readout chips is an attractive option. In this paper, we present the first results of microchannel prototypes with circulating, two-phase CO2 and compare them to simulations. We also discuss a practical design of upgraded VELO detector for the LHCb experiment employing this approach.

  12. Behavioral responses of dairy heifers confined to the evaporative cooling system

    Directory of Open Access Journals (Sweden)

    Gianni Aguiar da Silva

    2013-03-01

    Full Text Available The research aimed to evaluate the influence of evaporative cooling system (AECS on the behavioral variables of Holstein dairy heifers kept in confinement. Twelve heifers were used, divided into three treatments: 1 ventilation and fogging by AECS when the temperature reached 25°C at any humidity, 2 ventilation and fogging by AECS when the temperature reached 25°C with relative humidity less than or equal to 70% and, 3 without cooling system. The experimental design consisted of a latin rectangle repeated twice. The environmental variables (dry bulb temperature, black globe temperature and relative humidity were collected daily through dataloggers throughout the experiment. In behavioral analysis were observed postures (standing and lying, the activities of the animals and the places where they were in the pen, in 15 minute intervals. However, there was no difference in the behavioral variables of animals between treatments.

  13. Cooling High Heat Flux Micro-Electronic Systems using Refrigerants in High Aspect Ratio Multi-Microchannel Evaporators

    OpenAIRE

    Costa-Patry, Etienne

    2011-01-01

    Improving the energy efficiency of cooling systems can contribute to reduce the emission of greenhouse gases. Currently, most microelectronic applications are air-cooled. Switching to two-phase cooling systems would decrease power consumption and allow for the reuse of the extracted heat. For this type of application, multi-microchannel evaporators are thought to be well adapted. However, such devices have not been tested for a wide range of operating...

  14. Study on Performance Improvement and Economical Aspect of Gas Turbine Power Plant Using Evaporative Cooling System

    Directory of Open Access Journals (Sweden)

    Hilman Syaeful Alam

    2015-12-01

    Full Text Available The study is intended to improve the performance of gas turbine engines in order to meet both electrical power demand and peak load in the power plant. In this paper, evaporative cooling system had been applied to improve the performance of gas turbine in Pesanggaran power plant in southern Bali Island, Indonesia. Moreover, the economic analysis was conducted to determine the capacity cost, operating cost and payback period due to the investment cost of the system. Based on the evaluation results, the power improvement for the three gas turbine units (GT1, GT2 and GT3 are 2.09%, 1.38%, and 1.28%, respectively. These results were not very significant when compared to the previous studies as well as on the aspects of SFC (Specific Fuel Consumption, heat rate and thermal efficiency. Based on the evaluation of the economic aspects, the reduction of production costs due to the application of evaporative cooling system was not economical, because it could not compensate the investment cost of the system and it resulted a very long payback period. These unsatisfactory results could be caused by the high relative humidity. Therefore, further studies are needed to investigate the other alternative technologies which are more suitable to the climate conditions in Indonesia.

  15. Evaporative CO$_2$ microchannel cooling for the LHCb VELO pixel upgrade

    CERN Document Server

    de Aguiar Francisco, Oscar A; Collins, Paula; Dumps, Raphael; John, Malcolm; Mapelli, Alessandro; Romagnoli, Giulia

    2015-01-01

    The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the system will be provided by evaporative CO$_2$ circulating in microchannels embedded within thin silicon plates. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASICs and sensors, the radiation hardness of CO$_2$, and very low contribution to the material budget. Although microchannel cooling is gaining considerable attention for applications related to microelectronics, it is still a novel technology for particle physics experiments, in particular when combined with evaporative CO$_2$ cooling. The R&D effort for LHCb is focused on the design and layout of the channels together with a fluidic connector and its attachment which must withstand pressures up to 170 bar. Even distribution of the coolant is ensured by means of the use o...

  16. An experimental study on the design, performance and suitability of evaporative cooling system using different indigenous materials

    Science.gov (United States)

    Alam, Md. Ferdous; Sazidy, Ahmad Sharif; Kabir, Asif; Mridha, Gowtam; Litu, Nazmul Alam; Rahman, Md. Ashiqur

    2017-06-01

    The present study aimed to evaluate the feasibility of coconut coir pads, jute fiber pads and sackcloth pads as alternative pad materials. Experimental measurements were conducted and the experimental data were quantitative. The experimental work mainly focused on the effects of different types and thicknesses of evaporative cooling pads by using forced draft fan while changing the environmental conditions. Experiments are conducted in a specifically constructed test chamber having dimensions of 12'X8'X8', using a number of cooling pads (36"X26") with a variable thickness parameters of the evaporative cooling pads i.e., 50, 75 and 100 mm. Moreover, the experimental work involved the measurement of environmental parameters such as temperature, relative humidity, air velocity, water mass flow rate and pressure drops at different times during the day. Experiments were conducted at three different water mass flow rates (0.25 kgs-1, 0.40 kgs-1 & 0.55 kgs-1) and three different air velocities (3.6 ms-1, 4.6 ms-1& 5.6 ms-1). There was a significant difference between evaporative cooling pad types and cooling efficiency. The coconut coir pads yielded maximum cooling efficiency of 85%, whereas other pads yielded the following maximum cooling efficiency: jute fiber pads 78% and sackcloth 69% for higher air velocity and minimum mass flow rate. It is found that the maximum reduction in temperature between cooling pad inlet and outlet is 4°C with a considerable increase in humidity. With the increase of pad thickness there was an increment of cooling efficiency. The results obtained for environmental factors, indicated that there was a significant difference between environmental factors and cooling efficiency. In terms of the effect of air velocity on saturation efficiency and pressure drop, higher air velocity decreases saturation efficiency and increases pressure drop across the wetted pad for maximum flow rate. Convective heat transfer co-efficient has an almost linear

  17. Evaporative and sorptive cooling. Possibilities and limitations in air treatment.; Evaporativ och sorptiv kylning. Moejligheter och begraensningar vid luftbehandling

    Energy Technology Data Exchange (ETDEWEB)

    Lindholm, T. [Chalmers Univ. of Techn., Goeteborg (Sweden). Dept. of Building Services Engineering

    2001-10-01

    A primary demand for a good indoor climate in a building is that temperature and humidity are maintained at comfortable levels, regardless of the prevailing outdoor climate. Some buildings often have a heat surplus for a great part of the year due to internal activities, even in climates with moderate ambient temperatures. This heat surplus has to be removed in order to fulfil the specified requirements on the indoor climate. The focus in this report is on possibilities and limitations using evaporative and desiccant cooling to satisfy the cooling demands in such buildings. Today the most common technical solution is to use a compressor refrigeration system for air-conditioning. As a result of the greenhouse effect and the ozone depletion debate, the prerequisites for compressor refrigeration systems have been changed. Evaporative cooling is an interesting alternative to conventional compressor refrigeration systems. However, the use of evaporative cooling presupposes all-air systems. The use of such a system will also, to a large extent, be limited by ambient conditions as well as the settled demands on the indoor climate. High outdoor humidity levels have great influence on the supply-air temperature achievable, i.e., cooling loads possible to meet. One way to considerably reduce the influence of these limitations is to use desiccant cooling, i.e., to dehumidify the ambient air before the evaporative stages. In this report, a general methodology to describe possibilities and limitations for evaporative and desiccant cooling, is presented. The major advantage of this methodology is that it may give rise to an increased understanding of these processes and, hence, be a guide to a proper dimensioning.

  18. Effects of evaporative cooling on reproductive performance and milk production of dairy cows in hot wet conditions

    Science.gov (United States)

    Khongdee, S.; Chaiyabutr, N.; Hinch, G.; Markvichitr, K.; Vajrabukka, C.

    2006-05-01

    Fourteen animals of second and third lactation of Thai Friesian crossbred cows (87.5% Friesian × 12.5% Bos indicus) located at Sakol Nakhon Research and Breeding Centre, Department of Livestock Development, Ministry of Agriculture and Cooperatives, were divided randomly into two groups of seven each to evaluate the effects of evaporative cooling on reproductive and physiological traits under hot, humid conditions. Results indicated that installation of evaporating cooling in the open shed gave a further improvement in ameliorating heat stress in dairy cows in hot-wet environments by utilising the low humidity conditions that naturally occur during the day. The cows housed in an evaporatively cooled environment had both a rectal temperature and respiration rate (39.09°C, 61.39 breaths/min, respectively) significantly lower than that of the non-cooled cows (41.21°C; 86.87 breaths/min). The former group also had higher milk yield and more efficient reproductive performance (pregnancy rate and reduced days open) than the latter group. It is suggested that the non-evaporatively cooled cows did not gain benefit from the naturally lower heat stress during night time.

  19. Development of Wind Operated Passive Evaporative Cooling Structures for Storage of Tomatoes

    Directory of Open Access Journals (Sweden)

    M. O. Sunmonu

    2016-08-01

    Full Text Available A Wind operated passive evaporative cooler was developed. Two cooling chambers were made with clay container (cylindrical and square shapes. These two containers were separately inserted inside bigger clay pot inter- spaced with clay soil of 7 cm (to form pot-in-pot and wall-in wall with the outside structure wrapped with jute sack. The soil and the jute sacks were wetted with salt solution. Five blades were constructed inside the cooling chambers with aluminium material which were connected with a shaft to a vane located on a wooden cover outside the cooling chamber. The vanes (made of aluminium were to be powered by the wind which in turn rotates the blades inside the cooling chamber. The total volume of 40500cm3 and storage capacity of 31500cm3 were recorded for the square structures while total volume of 31792.5cm3 and storage capacity of 24727.5cm3 were recorded for the cylindrical structures. During the test period, the average temperatures of 27.07oC, 27.09oC and 33.6oC were obtained for the pot-in-pot (cylindrical, wall-in-wall (square and the ambient respectively. The average relative humidity of 92.27%, 91.99% and 69.41% were obtained for the pot-in-pot (cylindrical, wall-in-wall (square and the ambient respectively. The average minimum and maximum wind speed recorded for the month of October was 2.5m/s and 2.6m/s respectively

  20. An experimental model of the evaporative cooling system of a single powerful LED

    Directory of Open Access Journals (Sweden)

    Shatskiy Evgeny

    2017-01-01

    Full Text Available An experimental model of the evaporative cooling system of a single powerful LED with a natural circulation of the coolant capable of removing a heat flux density of more than 1 kW / cm2 is created. It is shown that on the finned surfaces the overheating relative to the saturation temperature in comparison with a smooth surface decreases up to three times for the heater with a diameter of 5 mm. There is up to two times increase in heat transfer coefficient on finned surfaces as compared to the smooth ones. For finned surfaces on the heater with a diameter of 1 mm the surface overheating relative to the saturation temperature decreases in four times. More than three times increase is observed for the heat transfer coefficient on finned surfaces as compared to the smooth ones.

  1. Micro channel evaporative $CO_2$ cooling for the upgrade of the LHCb vertex detector

    CERN Document Server

    Buytaert, J; Dumps, R; Greening, E; John, M; Leflat, A; Li, Y; Mapelli, A; Nomerotski, A; Romagnoli, G; Verlaat, B

    2013-01-01

    Local thermal management of detector electronics through ultra-thin micro-structured silicon cooling plates is a very promising technique for pixel detectors in high energy physics experiments, especially at the LHC where the heavily irradiated sensors must be operated at temperatures below − 20 1 C. It combines a very high thermal ef fi ciency with a very low addition of mass and space, and suppresses all problems of CTE mismatch between the heat source and the heat sink. In addition, the use of CO 2 as evaporative coolant liquid brings all the bene fi ts of reliable and stable operation, but the high pressures involved impose additional challenges on the micro channel design and the fl uidic connectivity. A series of designs have already been prototyped and tested for LHCb. The challenges, the current status of the measurements and the solutions under development will be described

  2. An experimental model of the evaporative cooling system of a single powerful LED

    Science.gov (United States)

    Shatskiy, Evgeny

    2017-10-01

    An experimental model of the evaporative cooling system of a single powerful LED with a natural circulation of the coolant capable of removing a heat flux density of more than 1 kW / cm2 is created. It is shown that on the finned surfaces the overheating relative to the saturation temperature in comparison with a smooth surface decreases up to three times for the heater with a diameter of 5 mm. There is up to two times increase in heat transfer coefficient on finned surfaces as compared to the smooth ones. For finned surfaces on the heater with a diameter of 1 mm the surface overheating relative to the saturation temperature decreases in four times. More than three times increase is observed for the heat transfer coefficient on finned surfaces as compared to the smooth ones.

  3. Development of fluorocarbon evaporative cooling recirculators and controls for the ATLAS inner silicon tracker

    CERN Document Server

    Bayer, C; Bonneau, P; Bosteels, Michel; Burckhart, H J; Cragg, D; English, R; Hallewell, G D; Hallgren, Björn I; Ilie, S; Kersten, S; Kind, P; Langedrag, K; Lindsay, S; Merkel, M; Stapnes, Steinar; Thadome, J; Vacek, V

    2000-01-01

    We report on the development of evaporative fluorocarbon cooling recirculators and their control systems for the ATLAS inner silicon tracker. We have developed a prototype circulator using a dry, hermetic compressor with C/sub 3/F/sup 8/ refrigerant, and have prototyped the remote-control analog pneumatic links for the regulation of coolant mass flows and operating temperatures that will be necessary in the magnetic field and radiation environment around ATLAS. pressure and flow measurement and control use 150+ channels of standard ATLAS LMB ("Local Monitor Board") DAQ and DACs on a multi-drop CAN network administered through a BridgeVIEW user interface. A hardwired thermal interlock system has been developed to cut power to individual silicon modules should their temperatures exceed safe values. Highly satisfactory performance of the circulator under steady state, partial-load and transient conditions was seen, with proportional fluid flow tuned to varying circuit power. Future developments, including a 6 kW...

  4. Performance evaluation of three different types of local evaporative cooling pads in greenhouses in Sudan.

    Science.gov (United States)

    Ahmed, Egbal Mohammed; Abaas, Osama; Ahmed, Mohammed; Ismail, Mohd Rodzi

    2011-01-01

    This study was conducted in Date Palm Technology Company Limited, Shambat, Khartoum State. To evaluate performance of three types of evaporative cooling pads for greenhouses (celdek pads, straw pads and sliced wood pads), as compared to the conditions outside the greenhouses (control), for pads. Performance evaluation includes environmental parameters (temperature and relative humidity at 8 am, 1 pm and 6 pm) and crop parameters (length and stem diameter, leaves number and width, fruit length and diameter, fruit weight and dry matter and yield). The results obtained for the temperature at 8 am showed that there was no significant difference (0.05) inside the greenhouses, while a high significant difference between the conditions inside and outside of the greenhouses was found. Significant differences were found at 1 pm and 6 pm between all treatments as compared to the conditions outside the greenhouses, and the results obtained for relative humidity showed high significant differences at 8 am and 1 pm inside the greenhouses and between inside and outside the greenhouse, respectively, while there was no significant difference at 6 pm inside the greenhouses and between inside and outside the greenhouses. On the other hand, the results obtained for crop parameters showed that there were significant differences between all parameters inside the greenhouses and outside the greenhouses; however, the greenhouses with sliced wood pads gave the highest yield and the greenhouses with straw pads gave the least and conditions outside gave the lowest. This study indicated that the sliced wood pads are better than the other evaporative cooling pads.

  5. Experimental analysis of heat and mass transfer phenomena in a direct contact evaporative cooling tower

    Energy Technology Data Exchange (ETDEWEB)

    Lemouari, M. [Department of Processes Engineering, Faculty of Sciences and Engineering, University of Bejaia (Algeria); Boumaza, M. [Department of Chemical Engineering, College of Engineering - King Saud University, P.O. Box 800, Riyadh (Saudi Arabia); Kaabi, A. [Department of Genie Climatique, Faculty of Engineering, University of Constantine, Constantine (Algeria)

    2009-06-15

    This paper deals with an experimental analysis of simultaneous heat and mass transfer phenomena between water and air by direct contact in a packed cooling tower. The tower is filled with a ''VGA.'' (Vertical Grid Apparatus) type packing. The packing is 0.42 m high and consists of four (04) galvanised sheets having a zigzag form, between which are disposed three (03) metallic vertical grids in parallel with a cross-sectional test area of 0.15 m x 0.148 m. This study investigates the effect of the air and water flow rates on the global heat and mass transfer coefficient as well as the evaporation rate of water into the air stream, for different inlet water temperatures. Two operating regimes were observed during the air/water contact inside the tower, a Pellicular Regime (PR) and a Bubble and Dispersion Regime (BDR). These two regimes can determine the best way to promote the heat and mass transfer phenomena in such device. The BDR regime seems to be more efficient than the Pellicular Regime, as it enables to achieve relatively higher values of the global heat and mass transfer coefficient and larger water evaporation rates. The comparison between the obtained results and some of those available in the literature for other types of packing indicates that this type possesses good heat and mass transfer characteristics. (author)

  6. Theory of evaporative cooling with energy-dependent elastic scattering cross section and application to metastable helium

    NARCIS (Netherlands)

    Tol, P.J.J.; Hogervorst, W.; Vassen, W.

    2004-01-01

    A model was developed to allow simulation of evaporative cooling experiments in situations where the elastic scattering cross section depends on collision energy. The model was used to simulate the number of atoms and temperature in a rf sweep for metastable helium. The value of the scattering

  7. Differential privacy-based evaporative cooling feature selection and classification with relief-F and random forests.

    Science.gov (United States)

    Le, Trang T; Simmons, W Kyle; Misaki, Masaya; Bodurka, Jerzy; White, Bill C; Savitz, Jonathan; McKinney, Brett A

    2017-09-15

    Classification of individuals into disease or clinical categories from high-dimensional biological data with low prediction error is an important challenge of statistical learning in bioinformatics. Feature selection can improve classification accuracy but must be incorporated carefully into cross-validation to avoid overfitting. Recently, feature selection methods based on differential privacy, such as differentially private random forests and reusable holdout sets, have been proposed. However, for domains such as bioinformatics, where the number of features is much larger than the number of observations p≫n , these differential privacy methods are susceptible to overfitting. We introduce private Evaporative Cooling, a stochastic privacy-preserving machine learning algorithm that uses Relief-F for feature selection and random forest for privacy preserving classification that also prevents overfitting. We relate the privacy-preserving threshold mechanism to a thermodynamic Maxwell-Boltzmann distribution, where the temperature represents the privacy threshold. We use the thermal statistical physics concept of Evaporative Cooling of atomic gases to perform backward stepwise privacy-preserving feature selection. On simulated data with main effects and statistical interactions, we compare accuracies on holdout and validation sets for three privacy-preserving methods: the reusable holdout, reusable holdout with random forest, and private Evaporative Cooling, which uses Relief-F feature selection and random forest classification. In simulations where interactions exist between attributes, private Evaporative Cooling provides higher classification accuracy without overfitting based on an independent validation set. In simulations without interactions, thresholdout with random forest and private Evaporative Cooling give comparable accuracies. We also apply these privacy methods to human brain resting-state fMRI data from a study of major depressive disorder. Code

  8. Development and test of the $\\rm CO_2$ evaporative cooling system for the LHCb UT Tracker Upgrade

    CERN Document Server

    Coelli, Simone

    2017-01-01

    Abstract: The LHCb upgrade requires a new silicon strip tracker detector placed between the vertex locator and the magnet. The new detector will have improved performance in charged particle tracking and triggering. The front-end electronics will be in the active area, close to the sensors: this is a key feature driving the mechanical and cooling detector design, together with the requirement to make the sensors work below −5°C, to withstand radiation damage. The new design exploits a cooling system based on $\\rm CO_2$ evaporation at temperatures around −25°C. The support structure for the sensor modules is a lightweight carbon fiber mechanical structure embedding a cooling pipe, designed to pass underneath the read-out ASICs, which are the main thermal power sources to be cooled down. Here a description of the detector will be given, with a main focus on the cooling system and on the progress done to its qualification.

  9. Investigation of the falling water flow with evaporation for the passive containment cooling system and its scaling-down criteria

    Science.gov (United States)

    Li, Cheng; Li, Junming; Li, Le

    2017-09-01

    Falling water evaporation cooling could efficiently suppress the containment operation pressure during the nuclear accident, by continually removing the core decay heat to the atmospheric environment. In order to identify the process of large-scale falling water evaporation cooling, the water flow characteristics of falling film, film rupture and falling rivulet were deduced, on the basis of previous correlation studies. The influences of the contact angle, water temperature and water flow rates on water converge along the flow direction were then numerically obtained and results were compared with the data for AP1000 and CAP1400 nuclear power plants. By comparisons, it is concluded that the water coverage fraction of falling water could be enhanced by either reducing the surface contact angle or increasing the water temperature. The falling water flow with evaporation for AP1000 containment was then calculated and the feature of its water coverage fraction was analyzed. Finally, based on the phenomena identification of falling water flow for AP1000 containment evaporation cooling, the scaling-down is performed and the dimensionless criteria were obtained.

  10. Investigation of the falling water flow with evaporation for the passive containment cooling system and its scaling-down criteria

    Science.gov (United States)

    Li, Cheng; Li, Junming; Li, Le

    2018-02-01

    Falling water evaporation cooling could efficiently suppress the containment operation pressure during the nuclear accident, by continually removing the core decay heat to the atmospheric environment. In order to identify the process of large-scale falling water evaporation cooling, the water flow characteristics of falling film, film rupture and falling rivulet were deduced, on the basis of previous correlation studies. The influences of the contact angle, water temperature and water flow rates on water converge along the flow direction were then numerically obtained and results were compared with the data for AP1000 and CAP1400 nuclear power plants. By comparisons, it is concluded that the water coverage fraction of falling water could be enhanced by either reducing the surface contact angle or increasing the water temperature. The falling water flow with evaporation for AP1000 containment was then calculated and the feature of its water coverage fraction was analyzed. Finally, based on the phenomena identification of falling water flow for AP1000 containment evaporation cooling, the scaling-down is performed and the dimensionless criteria were obtained.

  11. Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli).

    Science.gov (United States)

    McKechnie, Andrew E; Smit, Ben; Whitfield, Maxine C; Noakes, Matthew J; Talbot, William A; Garcia, Mateo; Gerson, Alexander R; Wolf, Blair O

    2016-07-15

    Sandgrouse (Pterocliformes) are quintessential examples of avian adaptation to desert environments, but relatively little is known about the limits to their heat tolerance and evaporative cooling capacity. We predicted that evaporative cooling in Burchell's sandgrouse (Pterocles burchelli) is highly efficient and provides the basis for tolerance of very high air temperature (Ta). We measured body temperature (Tb), resting metabolic rate (RMR) and evaporative water loss (EWL) at Ta between 25°C and ∼58°C in birds exposed to successive increments in Ta Normothermic Tb averaged 39.0°C, lower than typical avian values. At Ta>34.5°C, Tb increased linearly to a maximum of 43.6°C at Ta=56°C. The upper critical limit of thermoneutrality (Tuc) was Ta=43.8°C, closely coinciding with the onset of panting and gular flutter. Above the Tuc, RMR increased 2.5-fold to 2.89 W at Ta=56°C, a fractional increase far exceeding that of many other species under comparable conditions. Rates of EWL increased rapidly at Ta>42.9°C to 7.84±0.90 g h(-1) at Ta=56°C, an 11-fold increase above minimal levels. Maximum evaporative cooling efficiency (ratio of evaporative heat loss to metabolic heat production) was 2.03, but could be as high as 2.70 if our assumption that the birds were metabolising lipids is incorrect. Thermoregulation at very high Ta in P. burchelli was characterised by large increases in RMR and EWL, and is much less efficient than in taxa such as columbids and caprimulgids. © 2016. Published by The Company of Biologists Ltd.

  12. Capturing the spectrum of interaction effects in genetic association studies by simulated evaporative cooling network analysis.

    Directory of Open Access Journals (Sweden)

    Brett A McKinney

    2009-03-01

    Full Text Available Evidence from human genetic studies of several disorders suggests that interactions between alleles at multiple genes play an important role in influencing phenotypic expression. Analytical methods for identifying Mendelian disease genes are not appropriate when applied to common multigenic diseases, because such methods investigate association with the phenotype only one genetic locus at a time. New strategies are needed that can capture the spectrum of genetic effects, from Mendelian to multifactorial epistasis. Random Forests (RF and Relief-F are two powerful machine-learning methods that have been studied as filters for genetic case-control data due to their ability to account for the context of alleles at multiple genes when scoring the relevance of individual genetic variants to the phenotype. However, when variants interact strongly, the independence assumption of RF in the tree node-splitting criterion leads to diminished importance scores for relevant variants. Relief-F, on the other hand, was designed to detect strong interactions but is sensitive to large backgrounds of variants that are irrelevant to classification of the phenotype, which is an acute problem in genome-wide association studies. To overcome the weaknesses of these data mining approaches, we develop Evaporative Cooling (EC feature selection, a flexible machine learning method that can integrate multiple importance scores while removing irrelevant genetic variants. To characterize detailed interactions, we construct a genetic-association interaction network (GAIN, whose edges quantify the synergy between variants with respect to the phenotype. We use simulation analysis to show that EC is able to identify a wide range of interaction effects in genetic association data. We apply the EC filter to a smallpox vaccine cohort study of single nucleotide polymorphisms (SNPs and infer a GAIN for a collection of SNPs associated with adverse events. Our results suggest an important

  13. Evaporative cooling in late-gestation Murrah buffaloes potentiates immunity around transition period and overcomes reproductive disorders.

    Science.gov (United States)

    Aarif, Ovais; Aggarwal, Anjali

    2015-10-15

    The objective of the study was to observe the effect of evaporative cooling during late gestation on immunity around the transition period and the probable outcome on reproductive disorders in Murrah buffaloes. Sixteen pregnant dry Murrah buffaloes at 60 days prepartum were selected and divided into two groups of eight animals each. Group 1 buffaloes remained without the provision of cooling, whereas the second group of buffaloes was managed under fans and mist cooling during the dry period. After parturition, all the animals were managed under evaporative cooling. Dry matter intake was significantly (P animals at -15, 0, and +20 days of parturition. Cortisol and prolactin levels were significantly (P animals at -15 and 0 days of parturition. However, prolactin was significantly (P animals at +20 days. Messenger RNA expression of prolactin receptor gene (PRL-R) was upregulated and suppressor of cytokine signaling gene 1 (SOCS-1) was downregulated in cooled animals at -20, 0, and +20 days of parturition. Tumor necrosis factor α and interleukin 4 levels remained significantly (P animals at -20, 0, and +20 days of parturition. Interleukin 6 was significantly (P animals at -20 and 0 days. Interferon γ levels were significantly higher at -20 and +20 days of parturition in cooled relative to noncooled animals. The reproductive disorders such as retention of placenta, metritis, and endometritis occurred at the rate of 37.25%, 25%, and 12.25% in the noncooled group, whereas only retention of placenta was observed in the cooled (12.5%) group. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Performance investigation of a waste heat-driven 3-bed 2-evaporator adsorption cycle for cooling and desalination

    KAUST Repository

    Thu, Kyaw

    2016-06-13

    Environment-friendly adsorption (AD) cycles have gained much attention in cooling industry and its applicability has been extended to desalination recently. AD cycles are operational by low-temperature heat sources such as exhaust gas from processes or renewable energy with temperatures ranging from 55 °C to 85 °C. The cycle is capable of producing two useful effects, namely cooling power and high-grade potable water, simultaneously. This article discusses a low temperature, waste heat-powered adsorption (AD) cycle that produces cooling power at two temperature-levels for both dehumidification and sensible cooling while providing high-grade potable water. The cycle exploits faster kinetics for desorption process with one adsorber bed under regeneration mode while full utilization of the uptake capacity by adsorbent material is achieved employing two-stage adsorption via low-pressure and high-pressure evaporators. Type A++ silica gel with surface area of 863.6 m2/g and pore volume of 0.446 cm3/g is employed as adsorbent material. A comprehensive numerical model for such AD cycle is developed and the performance results are presented using assorted hot water and cooling water inlet temperatures for various cycle time arrangements. The cycle is analyzed in terms of key performance indicators i.e.; the specific cooling power (SCP), the coefficient of performance (COP) for both evaporators and the overall system, the specific daily water production (SDWP) and the performance ratio (PR). Further insights into the cycle performance are scrutinized using a Dühring diagram to depict the thermodynamic states of the processes as well as the vapor uptake behavior of adsorbent. In the proposed cycle, the adsorbent materials undergo near saturation conditions due to the pressurization effect from the high pressure evaporator while faster kinetics for desorption process is exploited, subsequently providing higher system COP, notably up to 0.82 at longer cycle time while the

  15. Transfer Efficiency and Cooling Cost by Thermal Loss based on Nitrogen Evaporation Method for Superconducting MAGLEV System

    Science.gov (United States)

    Chung, Y. D.; Kim, D. W.; Lee, C. Y.

    2017-07-01

    This paper presents the feasibility of technical fusion between wireless power transfer (WPT) and superconducting technology to improve the transfer efficiency and evaluate operating costs such as refrigerant consumption. Generally, in WPT technology, the various copper wires have been adopted. From this reason, the transfer efficiency is limited since the copper wires of Q value are intrinsically critical point. On the other hand, as superconducting wires keep larger current density and relatively higher Q value, the superconducting resonance coil can be expected as a reasonable option to deliver large transfer power as well as improve the transfer ratio since it exchanges energy at a much higher rate and keeps stronger magnetic fields out. However, since superconducting wires should be cooled indispensably, the cooling cost of consumed refrigerant for resonance HTS wires should be estimated. In this study, the transmission ratios using HTS resonance receiver (Rx) coil and various cooled and noncooled copper resonance Rx coils were presented under non cooled copper antenna within input power of 200 W of 370 kHz respectively. In addition, authors evaluated cooling cost of liquid nitrogen for HTS resonance coil and various cooled copper resonance coils based on nitrogen evaporation method.

  16. Effect of the Evaporative Cooling on the Human Thermal Comfort and Heat Stress in a Greenhouse under Arid Conditions

    Directory of Open Access Journals (Sweden)

    A. M. Abdel-Ghany

    2013-01-01

    Full Text Available Thermal sensation and heat stress were evaluated in a plastic greenhouse, with and without evaporative cooling, under arid climatic conditions in Riyadh, Saudi Arabia. Suitable thermal comfort and heat stress scales were selected for the evaluation. Experiments were conducted in hot sunny days to measure the required parameters (i.e., the dry and wet bulb temperatures, globe temperature, natural wet bulb temperature, and solar radiation flux in the greenhouse. The results showed that in the uncooled greenhouse, workers are exposed to strong heat stress and would feel very hot most of the day time; they are safe from heat stress risk and would feel comfortable during night. An efficient evaporative cooling is necessary during the day to reduce heat stress and to improve the comfort conditions and is not necessary at night. In the cooled greenhouse, workers can do any activity: except at around noon they should follow a proposed working schedule, in which the different types of work were scheduled along the daytimes based on the heat stress value. To avoid heat stress and to provide comfort conditions in the greenhouses, the optimum ranges of relative humidity and air temperature are 48–55% and 24–28°C, respectively.

  17. Simulation Analysis of the Four Configurations of Solar Desiccant Cooling System Using Evaporative Cooling in Tropical Weather in Malaysia

    Directory of Open Access Journals (Sweden)

    M. M. S. Dezfouli

    2014-01-01

    Full Text Available A high demand for air conditioning systems exists in hot and humid regions because of the warm climate during the year. The high energy consumption of conventional air conditioning system is the reason for our investigation of the solar desiccant cooling system as an energy-efficient cooling system. Four model configurations were considered to determine the best configuration of a solar desiccant cooling system: one-stage ventilation, one-stage recirculation, two-stage ventilation, and two-stage recirculation. These models were stimulated for 8,760 hr of operation under hot and humid weather in Malaysia. Several parameters (i.e., coefficient of performance or COP, room temperature and humidity ratio, and the solar fraction of each system were evaluated by detecting the temperature and humidity ratio of the different points of each configuration by TRNSYS simulation. The latent and sensible loads of the test room were 0.875 kW and 2.625 kW, respectively. By investigating the simulation results of the four systems, the ventilation modes were found to be higher than the recirculation modes in the one- and two-stage solar desiccant cooling systems. The isothermal dehumidification COP of the two-stage ventilation was higher than that of the two-stage recirculation. Hence, the two-stage ventilation mode desiccant cooling system in a hot and humid area has higher efficiency than the other configurations.

  18. Experimental Study of the Cooling of Electrical Components Using Water Film Evaporation

    Directory of Open Access Journals (Sweden)

    S. Harmand

    2012-01-01

    Full Text Available Heat and mass transfer, which occur in the evaporation of a falling film of water, are studied experimentally. This evaporation allows the dissipation of the heat flux produced by twelve resistors, which simulate electrical components on the back side of an aluminium plate. On the front side of the plate, a falling film of water flows by the action of gravity. An inverse heat conduction model, associated with a spatial regularisation, was developed and produces the local heat fluxes on the plate using the measured temperatures. The efficiency of this evaporative process has been studied with respect to several parameters: imposed heat flux, inlet mass flow rate, and geometry. A comparison of the latent and sensible fluxes used to dissipate the imposed heat flux was studied in the case of a plexiglass sheet in front of the falling film at different distances from the aluminium plate.

  19. Comparative evaluation of naturally ventilated screenhouse and evaporative cooled greenhouse based on optimal vapor pressure deficit

    NARCIS (Netherlands)

    Shamshiri, Ramin; Ahmad, Desa; Wan Ismail, Wan Ishak; Man, Hasfalin Che; Zakaria, Abd Jamil; Beveren, Van Peter; Yamin, Muhammad

    2016-01-01

    The objective of this study was to compare two closed-field plant production environments for tomato cultivation based on optimal vapor pressure deficit (VPD). Experiment was carried out in tropical lowlands of Malaysia by collecting 11 days of sample data during March (2014), from an evaporative

  20. Improvement to Air2Air Technology to Reduce Fresh-Water Evaporative Cooling Loss at Coal-Based Thermoelectric Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ken Mortensen

    2011-12-31

    This program was undertaken to enhance the manufacturability, constructability, and cost of the Air2Air{TM} Water Conservation and Plume Abatement Cooling Tower, giving a validated cost basis and capability. Air2Air{TM} water conservation technology recovers a portion of the traditional cooling tower evaporate. The Condensing Module provides an air-to-air heat exchanger above the wet fill media, extracting the heat from the hot saturated moist air leaving in the cooling tower and condensing water. The rate of evaporate water recovery is typically 10% - 25% annually, depending on the cooling tower location (climate). This program improved the efficiency and cost of the Air2Air{TM} Water Conservation Cooling Tower capability, and led to the first commercial sale of the product, as described.

  1. Optimal design variable considerations in the use of phase change materials in indirect evaporative cooling

    Science.gov (United States)

    Chilakapaty, Ankit Paul

    The demand for sustainable, energy efficient and cost effective heating and cooling solutions is exponentially increasing with the rapid advancement of computation and information technology. Use of latent heat storage materials also known as phase change materials (PCMs) for load leveling is an innovative solution to the data center cooling demands. These materials are commercially available in the form of microcapsules dispersed in water, referred to as the microencapsulated phase change slurries and have higher heat capacity than water. The composition and physical properties of phase change slurries play significant role in energy efficiency of the cooling systems designed implementing these PCM slurries. Objective of this project is to study the effect of PCM particle size, shape and volumetric concentration on overall heat transfer potential of the cooling systems designed with PCM slurries as the heat transfer fluid (HTF). In this study uniform volume heat source model is developed for the simulation of heat transfer potential using phase change materials in the form of bulk temperature difference in a fully developed flow through a circular duct. Results indicate the heat transfer potential increases with PCM volumetric concentration with gradually diminishing returns. Also, spherical PCM particles offer greater heat transfer potential when compared to cylindrical particles. Results of this project will aid in efficient design of cooling systems based on PCM slurries.

  2. A Liquid Desiccant Enhanced Two Stage Evaporative Cooling System—Development and Performance Evaluation of a Test Rig

    Directory of Open Access Journals (Sweden)

    M. Mujahid Rafique

    2017-12-01

    Full Text Available Desiccant technology is found to be a good alternative to conventional cooling systems. It can provide better thermal comfort under hot and humid climatic conditions. The major component of a liquid desiccant cooling system is the desiccant dehumidifier which controls the latent cooling load. In this paper, a newly developed liquid desiccant enhanced evaporative cooling system has been tested experimentally. The effects of ambient conditions and other parameters on the performance of the system are investigated. The system performance curves which help to determine the air outlet conditions and coefficient of performance (COP of the system are drawn for a wide range of ambient air humidity ratios (0.010–0.026 kg/kg, ambient air temperature (25–40 °C, process air flow rate (1.5–8.0 kg/m2·s, regeneration air flow rate (1.5–4.5 kg/m2·s, and regeneration temperature (55–85 °C. The results showed that better supply air conditions are achieved for hot and humid climatic conditions with effectiveness of the system largely dependent on process and regeneration air flow rates, regeneration temperature, and humidity ratio of process air. The dehumidification performance is increased by 62% for a change of ambient air humidity ratio from 0.01 to 0.025 kg/kg. The thermal coefficient of performance improved by 50% for the above variation in humidity ratio. This shows that such thermally activated systems are feasible options for hot and humid climatic conditions as indicated by better performance under these conditions.

  3. Spectroscopic study of jet-cooled indole-3-carbinol by thermal evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Cheol Joo; Kim, Eun Bin; Min, Ahreum; Ahn, Ahreum; Seong, Yeon Guk; Choi, Myong Yong [Gyeongsang National University, Jinju (Korea, Republic of)

    2016-10-15

    Cruciferous vegetables such as cabbage, kale, broccoli, and cauliflower have relatively high levels of indole-3-carbinol (I3C), which can be used as a possible cancer preventative agent particularly for breast, cervical, colorectal, and other hormone-related cancers. Thus, this naturally occurring substance, I3C, is now being used in dietary supplements. In conclusion, we have succeeded in obtaining the R2PI spectrum of a thermally unstable sample, I3C, by using a thermal buffer (herein, uracil) for the first time. Use of thermal evaporation method for thermally unstable biomolecules using thermal buffers will allow us to explore more gas phase spectroscopic studies for their intrinsic physiological properties in the near future.

  4. Evaporative cooling by a pulsed jet spray of binary ethanol-water mixture

    Science.gov (United States)

    Karpov, P. N.; Nazarov, A. D.; Serov, A. F.; Terekhov, V. I.

    2015-07-01

    We have experimentally studied the heat transfer under conditions of pulsed multinozzle jet spray impact onto a vertical surface. The working coolant fluid was aqueous ethanol solution in a range of concentrations K 1 = 0-96%. The duration of spray pulses was τ = 2, 4, and 10 ms at a repetition frequency of 10 Hz. The maximum heat transfer coefficient was achieved at an ethanol solution concentration within 50-60%. The thermal efficiency of pulsed spray cooling grows with increasing ethanol concentration and decreasing jet spray pulse duration.

  5. A Study on Passive Cooling Methods by Evaporation and Solar Reflection on Rooftops in a Temperate Climate Region

    National Research Council Canada - National Science Library

    Jung, Suk-Jin; Yoon, Seong-Hwan

    2011-01-01

    .... In this study, an outdoor experiment was conducted using test specimens with a focus on passive cooling on rooftop surfaces in summertime to clarify the cooling effect of various types of passive rooftop cooling...

  6. Performance improvement of a hybrid air conditioning system using the indirect evaporative cooler with internal baffles as a pre-cooling unit

    Directory of Open Access Journals (Sweden)

    A.E. Kabeel

    2017-12-01

    Full Text Available In the present paper, the effects of the indirect evaporative cooler with internal baffle on the performance of the hybrid air conditioning system are numerically investigated. The hybrid air conditioning system contains two indirect evaporative coolers with internal baffle, one is utilized to pre-cool the air inlet to the desiccant wheel and the other is utilized to pre-cool the supply air inlet to the room. The effects of the inlet conditions of the process and reactivation air and working air ratio on the thermal performance of the hybrid air conditioning system have been analyzed. The results of this study show that in the hybrid air conditioning system for using the indirect evaporative cooler with internal baffle as a pre-cooling unit, the supply air temperature reduced by 21% and the coefficient of performance improved by 71% as compared to previous designs of the hybrid air conditioning system at the same inlet conditions. For increasing process air inlet temperature from 25 °C to 45 °C, supply air temperature increases from 12.7 °C to 14.2 °C, thermal COP increases from 1.87 to 2.84, and supply air relative humidity increases from 76.7% to 77.4%. Also, for increasing the reactivation air inlet temperature from 70 °C to 110 °C, supply air temperature dropped from 15.9 °C to 10.9 °C, supply air relative humidity dropped from 82.7% to 71.8%, and thermal COP dropped from 4.5 to 1.7. The recommended optimal air working ratio in the indirect evaporative cooler with internal baffle should be 0.15. Keywords: Desiccant material, Solar air collector, Evaporative cooler, Internal baffles, Air conditioning

  7. Desiccative and evaporative cooling systems in the field of energy change; Planung und Wirtschaftlichkeit von DEC-Anlagen im Umfeld der Energiewende

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Ronny [ILK Dresden gGmbH, Dresden (Germany). Bereich Luft- und Klimatechnik

    2013-06-15

    Desiccative and evaporative cooling systems are established on the market since a few years. They are energy efficient, they can use renewable energy and replace conventional compression cooling systems. Their primary energy demand is up to one-third below the demand of conventional air conditioning systems. Nevertheless there is a big difference on the market. The sales have been stagnating for years, although the energy change requires efficient and sustainable technologies in this Article, the existing prejudices and their thrift are discussed. (orig.)

  8. Evaporative snout cooling system on the performance of lactating sows and their litters in a subtropical region

    Directory of Open Access Journals (Sweden)

    Jonas Perin

    2015-01-01

    Full Text Available The aim of the study was to evaluate the influence of different temperature control systems on the voluntary feed intake (VFI, percentage of weight loss (PWL and performance of lactating sows as well as on the weight of their piglets. Two systems were used: traditional temperature control system (TTCS with curtain management and an evaporative snout cooling system (ESCS. The study was performed during the summer of 2011. After farrowing and at the weaning, 241 sows were weighed to evaluate the PWL during lactation. TTCS sows lost more weight (5.3±0.9%; P<0.05 than ESCS sows (2.2±0.9%. VFI was measured at intervals of four days in 32 primiparous and 39 multiparous sows. ESCS sows had higher VFI (5.8±0.2kg day-1; P<0.05 than TTCS sows (4.8±0.2kg day-1. Primiparous sows (4.4±0.2kg day-1 had a lower VFI than multiparous sows (6.3±0.2kg day-1, P<0.05 regardless of the temperature control system. Primiparous sows in the TTCS (10.9±1.3 days had a longer weaning-to-oestrus interval than primiparous sows in the ESCS (7.0±1.2 days, P<0.05. Subsequent litter size tended to be higher (P=0.095 in ESCS than in TTCS (12.0±0.5 and 10.9±0.6 piglets born, respectively. Litters housed in ESCS were heavier (65.3±1.4kg; P<0.05 at weaning than litters in TTCS (60.7±1.4kg. The results suggest that in general sows and piglets housed in the ESCS have better performance than sows and piglets housed in TTCS.

  9. Determining the Enthalpy of Vaporization of Salt Solutions Using the Cooling Effect of a Bubble Column Evaporator

    Science.gov (United States)

    Fan, Chao; Pashley, Richard M.

    2016-01-01

    The enthalpy of vaporization (?H[subscript vap]) of salt solutions is not easily measured, as a certain quantity of pure water has to be evaporated from a solution, at constant composition, and at a fixed temperature and pressure; then the corresponding heat input has to be measured. However, a simple bubble column evaporator (BCE) was used as a…

  10. Effects of an evaporative cooling system on plasma cortisol, IGF-I, and milk production in dairy cows in a tropical environment

    Science.gov (United States)

    Titto, Cristiane Gonçalves; Negrão, João Alberto; Titto, Evaldo Antonio Lencioni; Canaes, Taissa de Souza; Titto, Rafael Martins; Pereira, Alfredo Manuel Franco

    2013-03-01

    Access to an evaporative cooling system can increase production in dairy cows because of improved thermal comfort. This study aimed to evaluate the impact of ambient temperature on thermoregulation, plasma cortisol, insulin-like growth factor 1 (IGF-I), and productive status, and to determine the efficiency of an evaporative cooling system on physiological responses under different weather patterns. A total of 28 Holstein cows were divided into two groups, one with and the other without access to a cooling system with fans and mist in the free stall. The parameters were analyzed during morning (0700 hours) and afternoon milking (1430 hours) under five different weather patterns throughout the year (fall, winter, spring, dry summer, and rainy summer). Rectal temperature (RT), body surface temperature (BS), base of tail temperature (TT), and respiratory frequency (RF) were lower in the morning ( P < 0.01). The cooling system did not affect RT, and both the groups had values below 38.56 over the year ( P = 0.11). Cortisol and IGF-I may have been influenced by the seasons, in opposite ways. Cortisol concentrations were higher in winter ( P < 0.05) and IGF-I was higher during spring-summer ( P < 0.05). The air temperature and the temperature humidity index showed positive moderate correlations to RT, BS, TT, and RF ( P < 0.001). The ambient temperature was found to have a positive correlation with the physiological variables, independent of the cooling system, but cooled animals exhibited higher milk production during spring and summer ( P < 0.01).

  11. High efficiency two-step evaporator in a cooling system; Hocheffiziente zweistufige Verdampfung in einer Kaelteanlage - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Meister, R.; Haenni, E. [BMS-Energieanlagen AG, Wilderswil (Switzerland)

    2005-07-01

    A two-step evaporator was installed in parallel in an existing refrigeration plant with an operating capacity Q{sub o} of 130 kW. This ensured the possibility of a practical comparison between conventional evaporation and our high-efficiency two-step evaporator, without having to resort only to theoretical data. The result of this virtually one-on-one comparison in identical ambient conditions (which is not normally possible, as two systems cannot generally be installed in parallel) has confirmed what the advance calculations demonstrated, i.e. a 10% improvement in performance provided by the high-efficiency two-step evaporator. Thanks to the changeover from semi-floated to overflow operation (only tested in winter) it was possible, again as shown in previous calculations, to achieve an additional increase in performance of 5%. A basic objective was to use the high-efficiency two-step evaporator to provide stable performance in any operating situation - i.e. even after defrosting. This objective was achieved in both operating modes: semi-floated and overflow. Summer operation in overflow mode remains to be tested however, as the system has only been running in this mode since November 2004. (author)

  12. Evaporation of Droplets in Plasma Spray-Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-10-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter heat transfer.

  13. Melting and evaporation analysis of the first wall in a water-cooled breeding blanket module under vertical displacement event by using the MARS code

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon-Woo [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Cho, Hyoung-Kyu, E-mail: chohk@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Park, Goon-Cherl [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Im, Kihak [National Fusion Research Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133 (Korea, Republic of)

    2017-05-15

    Highlights: • Material phase change of first wall was simulated for vertical displacement event. • An in-house first wall module was developed to simulate melting and evaporation. • Effective heat capacity method and evaporation model were proposed. • MARS code was proposed to predict two-phase phenomena in coolant channel. • Phase change simulation was performed by coupling MARS and in-house module. - Abstract: Plasma facing components of tokamak reactors such as ITER or the Korean fusion demonstration reactor (K-DEMO) can be subjected to damage by plasma instabilities. Plasma disruptions like vertical displacement event (VDE) with high heat flux, can cause melting and vaporization of plasma facing materials and burnout of coolant channels. In this study, to simulate melting and vaporization of the first wall in a water-cooled breeding blanket under VDE, one-dimensional heat equations were solved numerically by using an in-house first wall module, including phase change models, effective heat capacity method, and evaporation model. For thermal-hydraulics, the in-house first wall analysis module was coupled with the nuclear reactor safety analysis code, MARS, to take advantage of its prediction capability for two-phase flow and critical heat flux (CHF) occurrence. The first wall was proposed for simulation according to the conceptual design of the K-DEMO, and the heat flux of plasma disruption with a value of 600 MW/m{sup 2} for 0.1 s was applied. The phase change simulation results were analyzed in terms of the melting and evaporation thicknesses and the occurrence of CHF. The thermal integrity of the blanket first wall is discussed to confirm whether the structural material melts for the given conditions.

  14. Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert doves and quail.

    Science.gov (United States)

    Smith, Eric Krabbe; O'Neill, Jacqueline; Gerson, Alexander R; Wolf, Blair O

    2015-11-01

    Birds in subtropical deserts face significant thermoregulatory challenges because environmental temperatures regularly exceed avian body temperature. To understand the differing susceptibility of desert birds to increasing temperatures, we examined thermoregulatory performance and estimated heat tolerance limits (HTLs) for three Sonoran Desert nesting bird species - Gambel's quail, mourning doves and white-winged doves. Using flow-through respirometry we measured daytime resting metabolism, evaporative water loss and real-time body temperature at air temperatures (T(air)) from 30°C to 66°C. We found marked increases in resting metabolism at the upper critical temperature (T(uc)), which was significantly lower in the quail (T(air)=41.1°C) than in both dove species (T(air)=45.9-46.5°C). Gambel's quail maintained low resting metabolic rates and low rates of evaporative water loss at their T(uc) (0.71 W and 1.20 g H2O h(-1), respectively), but were more sensitive to increasing air temperature, reaching their HTL at T(air) of 52°C. Mourning doves and white-winged doves maintained low resting metabolic rates (0.66 and 0.94 W), but higher rates of evaporative water loss (1.91 and 2.99 g H2O h(-1)) at their T(uc) and reached their HTL at T(air) of 58-60°C. Mass-specific evaporative water loss in white-winged doves (147 g) and mourning doves (104 g) was 45% and 30% greater, respectively, than the rate observed in Gambel's quail (161 g) at Tair of 48°C. Higher rates of evaporation and higher T(uc) made the doves exceptionally heat tolerant, allowing them to maintain body temperatures at least 14°C below air temperatures as high as 60°C (140°F). © 2015. Published by The Company of Biologists Ltd.

  15. Potential of indirect evaporative passive cooling with embedded tubes in a humid tropical climate : applications in a typical hot humid climate

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Chavez, J.R. [Univ. Autonoma Metropolitana-Azcapotzalco, Mexico City (Mexico). Dept. de Medio Ambiente, Laboratorio de Investigaciones en Arquitectura Bioclimatica; Givoni, B. [California Univ., Los Angeles, CA (United States); BGU, Beer Sheva (Israel); Viveros, O. [Cristobal Colon Univ., Veracruz (Mexico)

    2009-07-01

    The use of passive cooling techniques in buildings in hot and humid regions can reduce energy consumption while increasing thermal comfort for occupants. A study was conducted in the City of Veracruz, Mexico to investigate the performance of tubes embedded in the roof of the Gulf Meteorological Prevision Centre. Two identical insulated experimental cells were used, one serving as the control and the other one as the test unit, where the technique of embedded tubes in the roof was implemented and investigated during a typical overheating season. Results showed that this indirect evaporative cooling system is an effective strategy to reduce indoor temperatures without increasing the indoor humidity in buildings. The indoor maximum temperature was lowered by 2.72 K in the experimental test cell relative to the control unit. In addition, the resulting reduction of radiant temperatures in the test unit improved the thermal comfort of the occupants. It is expected that the implementation of this passive cooling technique will eventually contribute to reduced energy consumption and less use of air-conditioning systems in buildings, and thereby prevent emission of greenhouse gases to the atmosphere. 9 refs., 1 tab., 6 figs.

  16. Experimental evaluation of a breadboard heat and product-water removal system for a space-power fuel cell designed with static water removal and evaporative cooling

    Science.gov (United States)

    Hagedorn, N. H.; Prokipius, P. R.

    1977-01-01

    A test program was conducted to evaluate the design of a heat and product-water removal system to be used with fuel cell having static water removal and evaporative cooling. The program, which was conducted on a breadboard version of the system, provided a general assessment of the design in terms of operational integrity and transient stability. This assessment showed that, on the whole, the concept appears to be inherently sound but that in refining this design, several facets will require additional study. These involve interactions between pressure regulators in the pumping loop that occur when they are not correctly matched and the question of whether an ejector is necessary in the system.

  17. Modelling and experimental validation of the hot-gas defrost process of an air-cooled evaporator

    Energy Technology Data Exchange (ETDEWEB)

    Dopazo, J. Alberto; Fernandez-Seara, Jose; Uhia, Francisco J.; Diz, Ruben [Area de Maquinas y Motores Termicos, E.T.S. de Ingenieros Industriales, University of Vigo, Campus Lagoas-Marcosende No 9, 36310 Vigo, Pontevedra (Spain)

    2010-06-15

    A detailed transient simulation model has been developed to predict and evaluate the performance of the hot-gas defrost process of an air-coil evaporator. In the model, the defrost process is subdivided into six stages: preheating, tube frost melting start, fin frost melting start, air presence, tube-fin water film and dry-heating. In each stage, the control volume is subdivided into systems represented by a single node, which has the representative properties of the system. A finite difference approach was used to solve the model equations. The results include the time required to defrost, the distribution of the energy during defrost process, the instantaneous refrigerant properties and the instantaneous fin and tube temperature distribution. The results are compared with experimental data obtained in a local storage facility under actual operating conditions and also using data available in the literature. The model results substantially agree with the experimental data in both cases. (author)

  18. Heat and mass transfer are in the interaction of multi-pulsed spray with vertical surfaces in the regime of evaporative cooling

    Science.gov (United States)

    Karpov, P. N.; Nazarov, A. D.; Serov, A. F.; Terekhov, V. I.

    2017-10-01

    Sprays with a periodic supply drop phase have great opportunities to control the processes of heat transfer. We can achieve optimal evaporative modes of cooling by changing the pulse duration and the repetition frequency while minimizing flow of the liquid phase. Experimental data of investigation of local heat transfer for poorly heated large surface obtained on the original stand with multi nozzle managed the irrigation system impact of the gas-droplet flow present in this work. Researches on the contribution to the intensification of spray options were conducted. Also the growth rate was integral and local heat. Information instantaneous distribution of the heat flux in the description of the processes have helped us. Managed to describe two basic modes of heat transfer: Mode “insular” foil cooling and thick foil with forming of streams. Capacitive sensors allow to monitor the dynamics of the foil thickness, the birth-belt flow, forming and the evolution of waves generated by “bombing” the surface with the droplets.

  19. Improved defrosting of air-cooled evaporators. Stage 2: Analysis of defrosting processes; Verbesserung des Abtauens bei luftbeaufschlagten Verdampfern. Phase 2: Bewertung der Abtauprozesse

    Energy Technology Data Exchange (ETDEWEB)

    Bertsch, S.; Ehrbar, M. [Interstaatliche Hochschule fuer Technik Buchs, Labor fuer Thermodynamik und Kaeltetechnik, Buchs (Switzerland); Hubacher, P. [Hubacher Engineering, Engelburg (Switzerland)

    2002-07-01

    The fins of air-cooled evaporators freeze at evaporating temperatures below 0 {sup o}C. Air-water heat pumps are concerned with this problem, which causes a drop in heating performance. In addition the evaporator must be periodically defrosted. The subject of defrosting has been theoretically investigated in the first stage of this Project. In the second stage of the project, described here, the data of 7 heat pumps with hot gas defrosting and 6 heat pumps with reversed-cycle defrosting were analysed. The analysis of the reversed-cycle defrosting has shown that the defrosting energy consists not only of the electrical energy for defrosting, but also of indirect energy losses. These are a) the electrical energy to compensate the heat extraction of the space heating system during defrosting and b) the losses because of the 4-way reversing valve (leakage and heat exchange from the pressure side to the suction side and also a drop in pressure). The effects of the reversing valve are only small, but they add up because they have an effect during the whole heating cycle. The natural defrosting during longer shut-off periods with source temperatures above 0 {sup o}C is also taken into account. The results show that reversed cycle defrosting uses only about 30% of the electrical defrosting energy during the defrosting cycle, 50% is used for the compensation of the extracted heat of the space heating system and 20% for the losses of the 4-way reversing valve. At low water temperatures (35 {sup o}C), hot-gas defrosting needs more electrical energy for defrosting than systems with reversed cycle defrosting. At higher water temperatures (50 {sup o}C) the defrosting energy consumption of both systems is equal. On average, systems with hot gas defrosting need 2.3 kWh electrical energy for 100 kWh effective heat, and reversed-cycle systems need 2.1 kWh. The investigation of alternative defrosting systems and the effects of natural defrosting shows that there is a big potential

  20. Parametric Analysis of Design Parameter Effects on the Performance of a Solar Desiccant Evaporative Cooling System in Brisbane, Australia

    Directory of Open Access Journals (Sweden)

    Yunlong Ma

    2017-06-01

    Full Text Available Solar desiccant cooling is widely considered as an attractive replacement for conventional vapor compression air conditioning systems because of its environmental friendliness and energy efficiency advantages. The system performance of solar desiccant cooling strongly depends on the input parameters associated with the system components, such as the solar collector, storage tank and backup heater, etc. In order to understand the implications of different design parameters on the system performance, this study has conducted a parametric analysis on the solar collector area, storage tank volume, and backup heater capacity of a solid solar desiccant cooling system for an office building in Brisbane, Australia climate. In addition, a parametric analysis on the outdoor air humidity ratio control set-point which triggers the operation of the desiccant wheel has also been investigated. The simulation results have shown that either increasing the storage tank volume or increasing solar collector area would result in both increased solar fraction (SF and system coefficient of performance (COP, while at the same time reduce the backup heater energy consumption. However, the storage tank volume is more sensitive to the system performance than the collector area. From the economic aspect, a storage capacity of 30 m3/576 m2 has the lowest life cycle cost (LCC of $405,954 for the solar subsystem. In addition, 100 kW backup heater capacity is preferable for the satisfaction of the design regeneration heating coil hot water inlet temperature set-point with relatively low backup heater energy consumption. Moreover, an outdoor air humidity ratio control set-point of 0.008 kgWater/kgDryAir is more reasonable, as it could both guarantee the indoor design conditions and achieve low backup heater energy consumption.

  1. Testing and performance analysis of a hollow fiber-based core for evaporative cooling and liquid desiccant dehumidification

    DEFF Research Database (Denmark)

    Jradi, Muhyiddine; Riffat, Saffa

    2016-01-01

    In this study, an innovative heat and mass transfer core is proposed to provide thermal comfort and humidity control using a hollow fiber contactor with multiple bundles of micro-porous hollow fibers. The hollow fiberbased core utilizes 12 bundles aligned vertically, each with 1,000 packed polypr...... of 47%. Being cheap and simple to design with their attractive heat and mass transfer characteristics and the corresponding large surface area-to-volume ratio, hollow fiber membrane contactors provide a promising alternative for cooling and dehumidification applications.......In this study, an innovative heat and mass transfer core is proposed to provide thermal comfort and humidity control using a hollow fiber contactor with multiple bundles of micro-porous hollow fibers. The hollow fiberbased core utilizes 12 bundles aligned vertically, each with 1,000 packed...

  2. Boundary conditions for heat transfer and evaporative cooling in the trachea and air sac system of the domestic fowl: a two-dimensional CFD analysis.

    Science.gov (United States)

    Sverdlova, Nina S; Lambertz, Markus; Witzel, Ulrich; Perry, Steven F

    2012-01-01

    Various parts of the respiratory system play an important role in temperature control in birds. We create a simplified computational fluid dynamics (CFD) model of heat exchange in the trachea and air sacs of the domestic fowl (Gallus domesticus) in order to investigate the boundary conditions for the convective and evaporative cooling in these parts of the respiratory system. The model is based upon published values for respiratory times, pressures and volumes and upon anatomical data for this species, and the calculated heat exchange is compared with experimentally determined values for the domestic fowl and a closely related, wild species. In addition, we studied the trachea histologically to estimate the thickness of the heat transfer barrier and determine the structure and function of moisture-producing glands. In the transient CFD simulation, the airflow in the trachea of a 2-dimensional model is evoked by changing the volume of the simplified air sac. The heat exchange between the respiratory system and the environment is simulated for different ambient temperatures and humidities, and using two different models of evaporation: constant water vapour concentration model and the droplet injection model. According to the histological results, small mucous glands are numerous but discrete serous glands are lacking on the tracheal surface. The amount of water and heat loss in the simulation is comparable with measured respiratory values previously reported. Tracheal temperature control in the avian respiratory system may be used as a model for extinct or rare animals and could have high relevance for explaining how gigantic, long-necked dinosaurs such as sauropoda might have maintained a high metabolic rate.

  3. Boundary conditions for heat transfer and evaporative cooling in the trachea and air sac system of the domestic fowl: a two-dimensional CFD analysis.

    Directory of Open Access Journals (Sweden)

    Nina S Sverdlova

    Full Text Available Various parts of the respiratory system play an important role in temperature control in birds. We create a simplified computational fluid dynamics (CFD model of heat exchange in the trachea and air sacs of the domestic fowl (Gallus domesticus in order to investigate the boundary conditions for the convective and evaporative cooling in these parts of the respiratory system. The model is based upon published values for respiratory times, pressures and volumes and upon anatomical data for this species, and the calculated heat exchange is compared with experimentally determined values for the domestic fowl and a closely related, wild species. In addition, we studied the trachea histologically to estimate the thickness of the heat transfer barrier and determine the structure and function of moisture-producing glands. In the transient CFD simulation, the airflow in the trachea of a 2-dimensional model is evoked by changing the volume of the simplified air sac. The heat exchange between the respiratory system and the environment is simulated for different ambient temperatures and humidities, and using two different models of evaporation: constant water vapour concentration model and the droplet injection model. According to the histological results, small mucous glands are numerous but discrete serous glands are lacking on the tracheal surface. The amount of water and heat loss in the simulation is comparable with measured respiratory values previously reported. Tracheal temperature control in the avian respiratory system may be used as a model for extinct or rare animals and could have high relevance for explaining how gigantic, long-necked dinosaurs such as sauropoda might have maintained a high metabolic rate.

  4. Water stress reduces evaporative cooling in hybrid poplars during hot drought: genotype influences degree of coupling between thermal stress and atmosphere

    Science.gov (United States)

    Fojtik, A. C.; Barnes, M.; Breshears, D. D.; Law, D.; Moore, D. J.

    2016-12-01

    Climate change is projected to increase global temperatures as well as the frequency and severity of drought in many regions worldwide. Potential consequences of hotter drought include widespread forest mortality and ecosystem reorganization. Of concern is the response of woody plants, especially commercially significant species, to drought exacerbated by higher temperatures. Quantifying the physiological effects of hot drought on woody plants can improve understanding of their limitations and ability to adapt to projected conditions. Here we test an association between water stress and thermal stress in two genotypes of hybrid poplar trees during a naturally occurring hot drought in Southern Arizona. Genotype 57-276 had small, diamond-shaped leaves, while genotype R-270 had large, rounded leaves. We hypothesized that the degree of coupling between the atmosphere and leaf temperature would vary with genotype due to the effects of leaf size on boundary layer. We compared pre-dawn water potential (Ψ) to the difference between leaf and air temperature (ΔT; a proxy for thermal stress), and meteorological variables including vapor pressure deficit (VPD), photosynthetically active radiation (PAR), and wind speed as the drought progressed. In both genotypes, Ψ was negatively related to ΔT when leaf temperature was higher than air temperature; this relationship was stronger in the large leaf genotype than the small leaf genotype. Leaves from highly stressed plants were the hottest compared to ambient air temperature. This suggests that water stress results in a reduction in leaf transpiration and associated evaporative cooling. Each genotype also had unique factors affecting ΔT. The small leaf genotype was more tightly coupled to the atmosphere, with ΔT influenced by PAR, and wind speed. This is consistent with smaller, diamond-shaped leaves, which result in a smaller leaf boundary layer that is more sensitive to atmospheric conditions. For the large leaf genotype,

  5. Measure Guideline: Evaporative Condensers

    Energy Technology Data Exchange (ETDEWEB)

    German, A.; Dakin, B.; Hoeschele, M.

    2012-03-01

    The purpose of this measure guideline on evaporative condensers is to provide information on a cost-effective solution for energy and demand savings in homes with cooling loads. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices. This document has been prepared to provide a process for properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs.

  6. Dew Point Evaporative Comfort Cooling

    Science.gov (United States)

    2012-11-01

    Sealing and winterization. All units should be sealed with caulk when installed and winterized during the off season to minimize infiltration in climate...15. v ASHRAE Standard 62.1-2010, http://www.techstreet.com/ashrae/standards/ashrae/62_1_2010?product_id=1720986 vi LEED 2009, http://www.usgbc.org

  7. Field trial of three different Plasmodium vivax-detecting rapid diagnostic tests with and without evaporative cool box storage in Afghanistan

    Directory of Open Access Journals (Sweden)

    Mohammad Nader

    2011-06-01

    Full Text Available Abstract Background Accurate parasitological diagnosis of malaria is essential for targeting treatment where more than one species coexist. In this study, three rapid diagnostic tests (RDTs (AccessBio CareStart (CSPfPan, CareStart PfPv (CSPfPv and Standard Diagnostics Bioline (SDBPfPv were evaluated for their ability to detect natural Plasmodium vivax infections in a basic clinic setting. The potential for locally made evaporative cooling boxes (ECB to protect the tests from heat damage in high summer temperatures was also investigated. Methods Venous blood was drawn from P. vivax positive patients in Jalalabad, Afghanistan and tested against a panel of six RDTs. The panel comprised two of each test type; one group was stored at room temperature and the other in an ECB. RDT results were evaluated against a consensus gold standard based on two double-read reference slides and PCR. The sensitivity, specificity and a measure of global performance for each test were determined and stratified by parasitaemia level and storage condition. Results In total, 306 patients were recruited, of which 284 were positive for P. vivax, one for Plasmodium malariae and none for Plasmodium falciparum; 21 were negative. All three RDTs were specific for malaria. The sensitivity and global performance index for each test were as follows: CSPfPan [98.6%, 95.1%], CSPfPv [91.9%, 90.5%] and SDBPfPv [96.5%, 82.9%], respectively. CSPfPv was 16% less sensitive to a parasitaemia below 5,000/μL. Room temperature storage of SDBPfPv led to a high proportion of invalid results (17%, which reduced to 10% in the ECB. Throughout the testing period, the ECB maintained ~8°C reduction over ambient temperatures and never exceeded 30°C. Conclusions Of the three RDTs, the CSPfPan test was the most consistent and reliable, rendering it appropriate for this P. vivax predominant region. The CSPfPv test proved unsuitable owing to its reduced sensitivity at a parasitaemia below 5,000/

  8. Representative shuttle evaporative heat sink

    Science.gov (United States)

    Hixon, C. W.

    1978-01-01

    The design, fabrication, and testing of a representative shuttle evaporative heat sink (RSEHS) system which vaporizes an expendable fluid to provide cooling for the shuttle heat transport fluid loop is reported. The optimized RSEHS minimum weight design meets or exceeds the shuttle flash evaporator system requirements. A cold trap which cryo-pumps flash evaporator exhaust water from the CSD vacuum chamber test facility to prevent water contamination of the chamber pumping equipment is also described.

  9. Tubular sublimatory evaporator heat sink

    Science.gov (United States)

    Webbon, B. W. (Inventor)

    1977-01-01

    An evaporative refrigerator or cooler comprising a bundle of spaced, porous walled tubes closed at one of their ends and vented to a vacuum at the other end is disclosed. The tube bundle is surrounded by a water jacket having a hot water inlet distribution manifold and a cooled water outlet through a plenum chamber. Hot water is pumped into the jacket to circulate around the tubes, and when this water meets the vacuum existing inside the tubes, it evaporates thereby cooling the water in the jacket. If cooling proceeds to the point where water penetrating or surrounding all or part of the tubes freezes, operation continues with local sublimation of the ice on the tubes while the circulating water attempts to melt the ice. Both sublimation and evaporation may take place simultaneously in different regions of the device.

  10. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    Science.gov (United States)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2017-02-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  11. Onderzoeksrapportage duurzaam koelen : EOS Renewable Cooling

    NARCIS (Netherlands)

    Broeze, J.; Sluis, van der S.; Wissink, E.

    2010-01-01

    For reducing energy use for cooling, alternative methods (that do not rely on electricity) are needed. Renewable cooling is based on naturally available resources such as evaporative cooling, free cooling, phase change materials, ground subcooling, solar cooling, wind cooling, night radiation &

  12. Modelling refrigerant distribution in microchannel evaporators

    DEFF Research Database (Denmark)

    Brix, Wiebke; Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    The effects of refrigerant maldistribution in parallel evaporator channels on the heat exchanger performance are investigated numerically. For this purpose a 1D steady state model of refrigerant R134a evaporating in a microchannel tube is built and validated against other evaporator models. A stu...... out of the evaporator is kept constant. It is shown that the cooling capacity of the evaporator is reduced significantly, both in the case of unevenly distributed inlet quality and for the case of non-uniform airflow on the outside of the channels.......The effects of refrigerant maldistribution in parallel evaporator channels on the heat exchanger performance are investigated numerically. For this purpose a 1D steady state model of refrigerant R134a evaporating in a microchannel tube is built and validated against other evaporator models. A study...

  13. Heating, ventilation and cooling

    CSIR Research Space (South Africa)

    Osburn, L

    2009-02-01

    Full Text Available air and diluting the humidity or mixing the cool humid air with the air from a conventional air conditioner. Climate Specific The performance of an evaporative cooler is highly dependant on atmospheric conditions. Evaporative coolers work best... that an installed system is being maintained correctly by competent persons to ensure both smooth and efficient operation as well as to prevent mould growth. Legionnaires disease is a concern within evaporative coolers if it is not maintained correctly...

  14. Evaporative cooling and cutaneous surface temperature of Holstein cows in tropical conditions Resfriamento evaporativo e temperatura cutânea de vacas Holandesas em ambiente tropical

    Directory of Open Access Journals (Sweden)

    Roberto Gomes da Silva

    2011-05-01

    Full Text Available The effects of skin temperature (T S on the rate of heat loss by cutaneous evaporation (E S in Holstein cows chronically exposed to sun, considering hair coat colour were studied. Sixteen purebred cows were measured for E S and T S at 01:00 p.m. after 6 hours of exposure to sun, on three body regions (flank, neck and gluteus and considering dark and white spots separately. Sweating rate (S and E S were measured by means of a ventilated capsule. Black skin areas presented mean S (138.9 ± 8.5 gm-2 h-1, E S (93.3 ± 5.7 Wm-2, and T S (33.1 ± 0.2°C higher than those in the white areas (109.5 ± 9.7 gm-2h-1, 73.6 ± 6.5 Wm-2 and 32.6 ± 0.2°C, respectively. There is an exponential relationship among cutaneous temperature and cutaneous evaporation, which can be represented by the equation: E S = 31.5 + exp{(T S - 27.9/2.19115}, with coefficient of determination r² = 0.68. Cutaneous evaporative heat loss remains almost constant around 48 Wm-2 until T S reaches nearly 31°C.Foram estudados os efeitos da temperatura cutânea (Ts sobre a taxa de termólise por evaporação cutânea (Es de vacas Holandesas cronicamente expostas ao sol, considerando a pigmentação do pelame. Dezesseis vacas puras de origem foram medidas quanto à evaporação e à temperatura cutâneas às 13 h, após 6 horas de exposição ao sol, no mesmo local (flanco, pescoço e glúteo e considerando separadamente as malhas negras e as brancas. A evaporação cutânea foi medida por meio de cápsula ventilada. Nas áreas negras a taxa de sudação (138,9 ± 8,5 g.m-2.h-1, a taxa de termólise por evaporação cutânea (93,3 ± 5,7 W.m-2 e a temperatura da superfície cutânea (33,1 ± 0,2°C foram maiores que nas áreas brancas (109,5 ± 9,7 g.m-2.h-1, 73,6 ± 6,5 W.m-2 e 32,6 ± 0,2°C, respectivamente. Há uma relação exponencial entre evaporação e temperatura cutâneas, que pode ser representada pela equação Es = 31,5+3,67 exp{(Ts-27,9/2,19115}, com coeficiente de

  15. Perfomance of an evaporative cooling system of a finishing phase swine barn Desempenho de um sistema de resfriamento evaporativo em instalações para suínos em fase de terminação

    Directory of Open Access Journals (Sweden)

    Valmir Sartor

    2003-02-01

    Full Text Available The thermal environment inside of a finishing phase swine barn has great influence on the success of swine production. This environment can be characterized by the black globe temperature and humidity index (BGHI, that represents the air temperature, humidity, wind speed and radiation. Due to the small number of Brazilian reports on this specific subject, this experiment was performed to verify the effect of one kind of evaporative cooling system on the thermal comfort of the animal in a swine barn, during the 98/99 summer at Patos de Minas, MG, Brazil. Two constructions were used, divided in 36 barns, each one with 15 animals, 110 to 150 days old. Along a side of one barn, four cooling devices were installed, with a ventilation system connected to a sprayer, to form an evaporative cooling system (ECS. The other barn did not have any cooling system being a control unity (COS. The ECS provided an improvement of the environmental thermal conditions, reducing the index of black globe temperature and humidity inside the building, from 83.5 to 82.4, during the critical period of the day (2 p.m.. The ECS provided also an improvement of the food conversion, from 3.27 to 2.88, and a tendency of a substantial weight gain, from 0.97 to 1.02 kg per day.O ambiente térmico no interior das instalações para suínos em fase de terminação tem importância vital para o sucesso da atividade suinícula. Esse ambiente pode ser representado pelo índice de temperatura de globo e umidade (ITGU, que inclui a temperatura, a umidade relativa e a velocidade do ar, e a radiação. Baseado nisto foi desenvolvido um trabalho com o objetivo de avaliar o efeito de um sistema de resfriamento evaporativo no conforto térmico de instalações para suínos em fase de terminação. O experimento foi realizado no período de verão (98/99 no município de Patos de Minas, MG. Foram utilizadas duas instalações divididas em 36 baias. Em cada baia foram alojados 15 animais por um

  16. Modelling refrigerant distribution in minichannel evaporators

    DEFF Research Database (Denmark)

    Brix, Wiebke

    distribution and on the cooling capacity of the evaporator. A one dimensional, steady state model of a minichannel evaporator is used for the study. An evaporator consisting of two multiport minichannels in parallel is used as a test case and two different refrigerants, R134a and R744 (CO2), are applied...... in the numerical experiments using the test case evaporator. The results show that the reduction in cooling capacity due to non-uniform airflow and non-uniform liquid and vapour distribution is generally larger when using R134a than when using CO2 as refrigerant. Comparing the capacity reductions with reductions......This thesis is concerned with numerical modelling of flow distribution in a minichannel evaporator for air-conditioning. The study investigates the impact of non-uniform airflow and non-uniform distribution of the liquid and vapour phases in the inlet manifold on the refrigerant mass flow...

  17. THE USE OF POROUS CERAMICS FOR EVAPORATIVE AND EVAPORATIVE – VAPOR –COMPRESSION SYSTEMS

    Directory of Open Access Journals (Sweden)

    Cheban D.N.

    2013-04-01

    Full Text Available The use of natural evaporative cooling is one of technical solutions of problem of energy efficiency in air conditioning systems. The use of evaporative cooling in the first combined cooling stage allows reducing the load on the condenser of the cooling machine due to reducing of the condensing temperature. This combination allows the use of this type of system in any climatic conditions, including regions with small water resources. Multi-porous ceramic structure is used in evaporative air coolers and water coolers in this case. The objective of this paper is to show advantages of the using of porous ceramic as a working attachment, and to show advantages of the proposed scheme of compression-evaporation systems in comparison with standard vapor compression systems. Experimental research proved the fact, that in the film mode cooling efficiency of air flow is between EA=0,6÷0,7 and is slightly dependent of water flow. For countries with hot and dry climate where reserves of water are limited, it is recommended to use cyclical regime with EA≈0,65 value, or to use channel regime with a value of EA≈0,55. This leads to considerable energy savings. It has been determined, that combined air conditioning system is completely closed on the consumption of water at the parameters of the outside air equal to tA =32ºC and XA>13g/kg (in system with direct evaporative cooling machine, and tA=32ºC and XA>12g/kg (in system with indirect evaporative cooling machine. With these parameters, the cost of water in evaporative cooling stage can be fully compensated by condensate from the evaporator chiller.

  18. Hybrid Wet/Dry Cooling for Power Plants (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Kutscher, C.; Buys, A.; Gladden, C.

    2006-02-01

    This presentation includes an overview of cooling options, an analysis of evaporative enhancement of air-cooled geothermal power plants, field measurements at a geothermal plant, a preliminary analysis of trough plant, and improvements to air-cooled condensers.

  19. Steam-Electric Power-Plant-Cooling Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Sonnichsen, J.C.; Carlson, H.A.; Charles, P.D.; Jacobson, L.D.; Tadlock, L.A.

    1982-02-01

    The Steam-Electric Power Plant Cooling Handbook provides summary data on steam-electric power plant capacity, generation and number of plants for each cooling means, by Electric Regions, Water Resource Regions and National Electric Reliability Council Areas. Water consumption by once-through cooling, cooling ponds and wet evaporative towers is discussed and a methodology for computation of water consumption is provided for a typical steam-electric plant which uses a wet evaporative tower or cooling pond for cooling.

  20. Vaporization Would Cool Primary Battery

    Science.gov (United States)

    Bhandari, Pradeep; Miyake, Robert N.

    1991-01-01

    Temperature of discharging high-power-density primary battery maintained below specified level by evaporation of suitable liquid from jacket surrounding battery, according to proposal. Pressure-relief valve regulates pressure and boiling temperature of liquid. Less material needed in cooling by vaporization than in cooling by melting. Technique used to cool batteries in situations in which engineering constraints on volume, mass, and location prevent attachment of cooling fins, heat pipes, or like.

  1. Uso do sistema de resfriamento adiabático evaporativo no conforto térmico de vacas da raça girolando Use of adiabatic evaporative cooling system in thermal comfort of girolando cows

    Directory of Open Access Journals (Sweden)

    Gledson L. P. de Almeida

    2011-07-01

    Full Text Available Objetivou-se, com esta pesquisa, avaliar diferentes tempos de exposição dos animais à climatização no curral de espera sobre os índices de conforto, parâmetros fisiológicos e produção de leite de vacas girolando 7/8. Consideraram-se tratamentos quatro tempos de exposição dos animais ao sistema de resfriamento adiabático evaporativo (SRAE, 0, 10, 20 e 30 min. O experimento foi realizado durante a estação de verão, com duração de 56 dias. Utilizaram-se 16 vacas com produção média de 18 kg de leite, adotando-se delineamento em quadrado latino 4 x 4. A temperatura de bulbo seco (Tbs, ºC e a umidade relativa (UR, %, foram registradas a cada minuto o que permitiu determinar a eficiência do SRAE por meio do índice de temperatura e umidade (ITU e entalpia (h. A frequência respiratória (FR, temperatura retal (TR e temperatura de pelame (TP, foram medidas antes e depois da climatização. O tratamento 30 min permitiu manter as variáveis ambientais e os índices de conforto dentro dos limites recomendados. As variáveis fisiológicas (FR, TR e TP mostraram valores inferiores no tratamento 30 min, o que refletiu positivamente na produção de leite, com aumento de 4,4%, quando comparado com o tratamento 0 min.The objective of this research was to evaluate different times of exposure of animals to cooling in the waiting pen on the comfort index, physiological parameters and milk production of girolando 7/8 cows. As treatments, four times of exposure of animals to adiabatic evaporative cooling system (AECS, 0, 10, 20 and 30 min were considered. The experiment was conducted during the summer season and lasted 56 days. Sixteen cows were used with an average daily milk production of 18 kg, distributed in 4 x 4 Latin square design. The dry bulb temperature (DBT and relative humidity (RH were recorded every minute, which allowed to determine the efficiency of the AECS through the Temperature and Humidity Index (THI and enthalpy (h. The

  2. Passive low energy cooling of buildings

    CERN Document Server

    Givoni, Baruch

    1994-01-01

    A practical sourcebook for building designers, providing comprehensive discussion of the impact of basic architectural choices on cooling efficiency, including the layout and orientation of the structure, window size and shading, exterior color, and even the use of plantings around the site. All major varieties of passive cooling systems are presented, with extensive analysis of performance in different types of buildings and in different climates: ventilation; radiant cooling; evaporative cooling; soil cooling; and cooling of outdoor spaces.

  3. Sheet Membrane Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  4. On the evaporation of ammonium sulfate solution

    Energy Technology Data Exchange (ETDEWEB)

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-07-16

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

  5. Technical Evaluation of Side Stream Filtration for Cooling Towers

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-10-01

    Cooling towers are an integral component of many refrigeration systems, providing comfort or process cooling across a broad range of applications. Cooling towers represent the point in a cooling system where heat is dissipated to the atmosphere through evaporation. Cooling towers are commonly used in industrial applications and in large commercial buildings to release waste heat extracted from a process or building system through evaporation of water.

  6. Avaliação de materiais alternativos utilizados na confecção de placas porosas para sistemas de resfriamento adiabático evaporativo Evaluation of alternative materials used for pad making in the evaporative cooling system

    Directory of Open Access Journals (Sweden)

    Ilda de F. F. Tinôco

    2002-04-01

    Full Text Available Objetivou-se, com este trabalho, a comparação entre a eficiência de alguns materiais porosos alternativos encontrados no Brasil: cinasita (argila expandida, serragem, fibra vegetal e carvão, para o Sistema de Resfriamento Adiabático Evaporativo (SRAE. O experimento se deu em condições de verão, em estufas situadas na Universidade Federal de Viçosa, Minas Gerais. O conforto térmico ambiente foi avaliado através do Índice de Temperatura de Globo Negro e Umidade (ITGU e Umidade Relativa do ar (UR, medidos diariamente, a cada duas horas, das 8 às 18 h. Os resultados obtidos foram interpretados através da análise de variância. Com base neste estudo, é possível inferir que a confecção de placas porosas para resfriadores evaporativos, utilizando-se os materiais cinasita e carvão vegetal, indica vantagens sobre os demais materiais estudados (serragem e fibra de madeira. No entanto, como não houve diferença estatística significativa em todos os horários, para os materiais testados e com base nos resultados de umidade relativa do ar e ITGU, sugere-se a condução de novas pesquisas, no sentido de se determinar a espessura correta da placa porosa, tendo em vista a obtenção correta da pressão estática do sistema, sendo este um fator determinante, no que se refere à sua eficiência.This study aimed to compare the efficiency of some alternative pad materials found in Brazil, such as the "cinasita" (an expanded clay, the sawdust, the vegetable fiber and coal. The experiment conducted in summer conditions, in greenhouses located in the Federal University of Viçosa, Minas Gerais. The comfort thermal atmosphere was evaluated through the Black Globe Humidity Index (BGHI and Relative Humidity (RH, measured daily, every two hours, between 8 to 18 h. The obtained results were interpreted through the variance analysis. On the basis of this study, it is possible to infer that the making of pad for evaporative cooling systems, using the

  7. Water Evaporation and Conformational Changes from Partially Solvated Ubiquitin

    Directory of Open Access Journals (Sweden)

    Saravana Prakash Thirumuruganandham

    2010-01-01

    Full Text Available Using molecular dynamics simulation, we study the evaporation of water molecules off partially solvated ubiquitin. The evaporation and cooling rates are determined for a molecule at the initial temperature of 300 K. The cooling rate is found to be around 3 K/ns, and decreases with water temperature in the course of the evaporation. The conformation changes are monitored by studying a variety of intermediate partially solvated ubiquitin structures. We find that ubiquitin shrinks with decreasing hydration shell and exposes more of its hydrophilic surface area to the surrounding.

  8. Not cool with cooling

    Science.gov (United States)

    Blain, Barry

    2010-09-01

    I confess that I may have missed the point of Roland Ennos's article "Urban cool" (August pp22-25), which describes methods of cooling cities by mitigating and reversing the effect of solar heating and includes an illustration of "evapotranspiration" in, of all places, Greater Manchester.

  9. Improvement of the defrosting process for air-cooled evaporators - Phase 3: technical implementation, laboratory tests and field trials; Verbesserung des Abtauens bei luftbeaufschlagten Verdampfern. Phase 3: technische Umsetzung, Labor- und Feldversuche

    Energy Technology Data Exchange (ETDEWEB)

    Ehrbar, M.; Bertsch, S.; Schwendener, S. [NTB Interstaatliche Hochschule fuer Technik Buchs, Buchs (Switzerland); Hubacher, P.; Bernal, C.; Hubacher, B. [Hubacher Engineering, Engelburg (Switzerland)

    2005-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) reviews the results of the third phase of a project that involved the examination of the technical possibilities of decreasing energy consumption during defrosting of heat pump evaporators. The five topics looked at include defrosting at temperatures above 2 {sup o}C using the unit's fan, defrosting with ambient air from the room where the evaporator is located, defrosting using stored heat, optimised hot-gas defrosting and 'natural' defrosting during the time when the system is not running. The authors state that many improvements can be obtained with only moderate technical measures being taken and at low cost.

  10. Evaporation From Lake Superior

    Science.gov (United States)

    Spence, C.; Blanken, P.; Hedstrom, N.; Leshkevich, G.; Fortin, V.; Charpentier, D.; Haywood, H.

    2009-05-01

    Evaporation is a critical component of the water balance of each of the Laurentian Great Lakes, and understanding the magnitude and physical controls of evaporative water losses are important for several reasons. Recently, low water levels in Lakes Superior and Michigan/Huron have had socioeconomic, ecological, and even meteorological impacts (e.g. water quality and quantity, transportation, invasive species, recreation, etc.). The recent low water levels may be due to increased evaporation, but this is not known as operational evaporation estimates are currently calculated as the residual of water or heat budgets. Perhaps surprisingly, almost nothing is known about evaporation dynamics from Lake Superior and few direct measurements of evaporation have been made from any of the Laurentian Great Lakes. This research is the first to attempt to directly measure evaporation from Lake Superior by deploying eddy covariance instrumentation. Results of evaporation rates, their patterns and controlling mechanisms will be presented. The direct measurements of evaporation are used with concurrent satellite and climate model data to extrapolate evaporation measurements across the entire lake. This knowledge could improve predictions of how climate change may impact the lake's water budget and subsequently how the water in the lake is managed.

  11. Cooling system having dual suction port compressor

    Science.gov (United States)

    Wu, Guolian

    2017-08-29

    A cooling system for appliances, air conditioners, and other spaces includes a compressor, and a condenser that receives refrigerant from the compressor. The system also includes an evaporator that receives refrigerant from the condenser. Refrigerant received from the condenser flows through an upstream portion of the evaporator. A first portion of the refrigerant flows to the compressor without passing through a downstream portion of the evaporator, and a second portion of the refrigerant from the upstream portion of the condenser flows through the downstream portion of the evaporator after passing through the upstream portion of the evaporator. The second portion of the refrigerant flows to the compressor after passing through the downstream portion of the evaporator. The refrigeration system may be configured to cool an appliance such as a refrigerator and/or freezer, or it may be utilized in air conditioners for buildings, motor vehicles, or other such spaces.

  12. Evaporation and Antievaporation instabilities

    OpenAIRE

    Addazi, Andrea; Marciano, Antonino

    2017-01-01

    We review (anti)evaporation phenomena within the context of quantum gravity and extended theories of gravity. The (anti)evaporation effect is an instability of the black hole horizon discovered in many different scenarios: quantum dilaton-gravity, $f(R)$-gravity, $f(T)$-gravity, string inspired black holes and brane-world cosmology. Evaporating and antievaporating black holes seem to have completely different thermodynamical features compared to standard semiclassical black holes. The purpose...

  13. Measure Guideline: Evaporative Condensers

    Energy Technology Data Exchange (ETDEWEB)

    German, A [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Dakin, B. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Hoeschele, M. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

    2012-03-01

    This measure guideline on evaporative condensers provides information on properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices.

  14. Experimental evaluation of cooling efficiency of the high performance cooling device

    Energy Technology Data Exchange (ETDEWEB)

    Nemec, Patrik, E-mail: patrik.nemec@fstroj.uniza.sk; Malcho, Milan, E-mail: milan.malcho@fstroj.uniza.sk [University of Žilina, Faculty of Mechanical Engineering, Department of Power Engineering, Univerzitna 1, 010 26 Žilina (Slovakia)

    2016-06-30

    This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

  15. Mixed feed evaporator

    Science.gov (United States)

    Vakil, Himanshu B.; Kosky, Philip G.

    1982-01-01

    In the preparation of the gaseous reactant feed to undergo a chemical reaction requiring the presence of steam, the efficiency of overall power utilization is improved by premixing the gaseous reactant feed with water and then heating to evaporate the water in the presence of the gaseous reactant feed, the heating fluid utilized being at a temperature below the boiling point of water at the pressure in the volume where the evaporation occurs.

  16. Evaporation from microreservoirs†

    Science.gov (United States)

    Lynn, N. Scott; Henry, Charles S.

    2010-01-01

    As a result of very large surface area to volume ratios, evaporation is of significant importance when dealing with lab-on-a-chip devices that possess open air/liquid interfaces. For devices utilizing a reservoir as a fluid delivery method to a microfluidic network, excessive evaporation can quickly lead to reservoir dry out and overall device failure. Predicting the rates of evaporation from these reservoirs is difficult because the position of the air/liquid interface changes with time as the volume of liquid in the reservoir decreases. Here we present a two-step method to accurately predict the rates of evaporation of such an interface over time. First, a simple method is proposed to determine the shape of an air/liquid meniscus in a reservoir given a specific liquid volume. Second, computational fluid dynamics simulations are used to calculate the instantaneous rate of evaporation for that meniscus shape. It is shown that the rate of evaporation is strongly dependent on the overall geometry of the system, enhanced in expanding reservoirs while suppressed in contracting reservoirs, where the geometry can be easily controlled with simple experimental methods. Using no adjustable parameters, the model accurately predicts the position of the inner moving contact line as a function of time following meniscus rupture in poly(dimethylsiloxane) reservoirs, and predicts the overall time for the persistence of liquid in those reservoirs to within 0.5 minutes. The methods in this study can be used to design holding reservoirs for lab-on-a-chip devices that involve no external control of evaporation, such that evaporation rates can be adjusted as necessary by modification of the reservoir geometry. PMID:19495463

  17. CO$_2$ cooling experience (LHCb)

    CERN Document Server

    Van Lysebetten, Ann; Verlaat, Bart

    2007-01-01

    The thermal control system of the LHCb VErtex LOcator (VELO) is a two-phase C0$_2$ cooling system based on the 2-Phase Accumulator Controlled Loop (2PACL) method. Liquid carbon dioxide is mechanically pumped in a closed loop, chilled by a water-cooled freon chiller and evaporated in the VELO detector. The main goal of the system is the permanent cooling of the VELO silicon sensors and of the heat producing front-end electronics inside a vacuum environment. This paper describes the design and the performance of the system. First results obtained during commissioning are also presented.

  18. Stochastic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  19. Maisotsenko cycle applications for multistage compressors cooling

    Science.gov (United States)

    Levchenko, D.; Yurko, I.; Artyukhov, A.; Baga, V.

    2017-08-01

    The present study provides the overview of Maisotsenko Cycle (M-Cycle) applications for gas cooling in compressor systems. Various schemes of gas cooling systems are considered regarding to their thermal efficiency and cooling capacity. Preliminary calculation of M-cycle HMX has been conducted. It is found that M-cycle HMX scheme allows to brake the limit of the ambient wet bulb temperature for evaporative cooling. It has demonstrated that a compact integrated heat and moisture exchange process can cool product fluid to the level below the ambient wet bulb temperature, even to the level of dew point temperature of the incoming air with substantially lower water and energy consumption requirements.

  20. Fracture behaviour of bread crust: Effect of bread cooling conditions

    NARCIS (Netherlands)

    Primo-Martín, C.; Beukelaer, H. de; Hamer, R.J.; Vliet, T. van

    2008-01-01

    The effect of air and vacuum cooling on the fracture behaviour and accompanying sound emission, moisture content and crispness of bread crust were investigated. Vacuum cooling resulted in rapid evaporative cooling of products that contained high moisture content. Fracture experiments showed a clear

  1. Forest evaporation models: Relationships between stand growth and evaporation

    CSIR Research Space (South Africa)

    Le Maitre, David C

    1997-06-01

    Full Text Available The relationships between forest stand structure, growth and evaporation were analysed to determine whether forest evaporation can be estimated from stand growth data. This approach permits rapid assessment of the potential impacts of afforestation...

  2. Evaporators for mobile waste heat recovery systems; Verdampfer zur Abwaermenutzung im Fahrzeug

    Energy Technology Data Exchange (ETDEWEB)

    Ambros, Peter; Fezer, Axel; Necker, Harald [Thesys GmbH, Kirchentellinsfurt (Germany); Orso,Jochen [Thesys GmbH, Kirchentellinsfurt (Germany); Hochschule Reutlingen (Germany)

    2011-01-15

    Thesys develops evaporators for waste heat recovery systems for mobile and stationary applications. These evaporators utilize the enthalpy availability of hot exhaust gas both in the cooled exhaust gas recirculation duct as well as in the main exhaust gas for example in the muffler. At present there are three different designs for evaporators under development. Prototype measurements have already partially proved their function and performance. (orig.)

  3. Use of fluorocarbons in the cooling of LHC experiments

    CERN Document Server

    Pimenta dos Santos, M

    2003-01-01

    Perfluorochemicals sold by 3M under the trade name 3M Fluorinert Electronic Liquids have been used for many years as heat transfer media in a variety of industries. The suitability of these liquids for the cooling of LHC experiment originates from their high dielectric strength as well as from their chemical stability under ionizing radiation. The Fluorinerts are clear, colorless, non-flammable with low toxicity and low corrosiveness. Additionally, they offer low global waming potential – GWP – and zero ozone-depletion potential – ODP. Some examples of fluorinert application in the cooling of LHC experiments will be presented : (a) the ATLAS Inner detector C3F8 evaporative cooling system (b) the ATLAS TRF C6F14 monophase cooling system and (c) the ALICE SPD “active heat pipe” C4F10 evaporative cooling system. A brief comparison of evaporative and monophase cooling systems will be outlined.

  4. The evaporative function of cockroach hygroreceptors.

    Directory of Open Access Journals (Sweden)

    Harald Tichy

    Full Text Available Insect hygroreceptors associate as antagonistic pairs of a moist cell and a dry cell together with a cold cell in small cuticular sensilla on the antennae. The mechanisms by which the atmospheric humidity stimulates the hygroreceptive cells remain elusive. Three models for humidity transduction have been proposed in which hygroreceptors operate either as mechanical hygrometers, evaporation detectors or psychrometers. Mechanical hygrometers are assumed to respond to the relative humidity, evaporation detectors to the saturation deficit and psychrometers to the temperature depression (the difference between wet-bulb and dry-bulb temperatures. The models refer to different ways of expressing humidity. This also means, however, that at different temperatures these different types of hygroreceptors indicate very different humidity conditions. The present study tested the adequacy of the three models on the cockroach's moist and dry cells by determining whether the specific predictions about the temperature-dependence of the humidity responses are indeed observed. While in previous studies stimulation consisted of rapid step-like humidity changes, here we changed humidity slowly and continuously up and down in a sinusoidal fashion. The low rates of change made it possible to measure instantaneous humidity values based on UV-absorption and to assign these values to the hygroreceptive sensillum. The moist cell fitted neither the mechanical hygrometer nor the evaporation detector model: the temperature dependence of its humidity responses could not be attributed to relative humidity or to saturation deficit, respectively. The psychrometer model, however, was verified by the close relationships of the moist cell's response with the wet-bulb temperature and the dry cell's response with the dry-bulb temperature. Thus, the hygroreceptors respond to evaporation and the resulting cooling due to the wetness or dryness of the air. The drier the ambient air

  5. Seminar 14 - Desiccant Enhanced Air Conditioning: Desiccant Enhanced Evaporative Air Conditioning (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.

    2013-02-01

    This presentation explains how liquid desiccant based coupled with an indirect evaporative cooler can efficiently produce cool, dry air, and how a liquid desiccant membrane air conditioner can efficiently provide cooling and dehumidification without the carryover problems of previous generations of liquid desiccant systems. It provides an overview to a liquid desiccant DX air conditioner that can efficiently provide cooling and dehumidification to high latent loads without the need for reheat, explains how liquid desiccant cooling and dehumidification systems can outperform vapor compression based air conditioning systems in hot and humid climates, explains how liquid desiccant cooling and dehumidification systems work, and describes a refrigerant free liquid desiccant based cooling system.

  6. Combat Vehicle Cooling/Heating Design Investigation.

    Science.gov (United States)

    1981-09-01

    Robert E., and Gaudio, Ralph, Jr.; "Application of the Ranque - Hilsch Vortex Tube to Aircrew Cooling Problems" Report AMRL-TR-67-124; Wright-Patterson... Tube 3-7 3.6 Expendable Heat Sink 3-9 3.7 Absorption Cooling 3-10 3.8 Evaporative Cooling 3-11 3.9 Summary 3-12 4.0 COMPARATIVE SYSTEM PERFORMANCE 4...3-6 3-5 Vortex Tube System Schematic 3-8 3-6 Expendable Heat Sink System Schematic 3-9 3-7 Absorption Cooling System Schematic 3-10 4-1 Air Cycle

  7. Stimulated Black Hole Evaporation

    CERN Document Server

    Spaans, Marco

    2016-01-01

    Black holes are extreme expressions of gravity. Their existence is predicted by Einstein's theory of general relativity and is supported by observations. Black holes obey quantum mechanics and evaporate spontaneously. Here it is shown that a mass rate $R_f\\sim 3\\times 10^{-8} (M_0/M)^{1/2}$ $M_0$ yr$^{-1}$ onto the horizon of a black hole with mass $M$ (in units of solar mass $M_0$) stimulates a black hole into rapid evaporation. Specifically, $\\sim 3 M_0$ black holes can emit a large fraction of their mass, and explode, in $M/R_f \\sim 3\\times 10^7 (M/M_0)^{3/2}$ yr. These stimulated black holes radiate a spectral line power $P \\sim 2\\times 10^{39} (M_0/M)^{1/2}$ erg s$^{-1}$, at a wavelength $\\lambda \\sim 3\\times 10^5 (M/M_0)$ cm. This prediction can be observationally verified.

  8. Conductive and evaporative precooling lowers mean skin temperature and improves time trial performance in the heat.

    Science.gov (United States)

    Faulkner, S H; Hupperets, M; Hodder, S G; Havenith, G

    2015-06-01

    Self-paced endurance performance is compromised by moderate-to-high ambient temperatures that are evident in many competitive settings. It has become common place to implement precooling prior to competition in an attempt to alleviate perceived thermal load and performance decline. The present study aimed to investigate precooling incorporating different cooling avenues via either evaporative cooling alone or in combination with conductive cooling on cycling time trial performance. Ten trained male cyclists completed a time trial on three occasions in hot (35 °C) ambient conditions with the cooling garment prepared by (a) immersion in water (COOL, evaporative); (b) immersion in water and frozen (COLD, evaporative and conductive); or (c) no precooling (CONT). COLD improved time trial performance by 5.8% and 2.6% vs CONT and COOL, respectively (both P COLD vs CONT (P COLD compared with COOL and CONT (both P COLD. The combination of evaporative and conductive cooling (COLD) had the greatest benefit to performance, which is suggested to be driven by reduced skin temperature following cooling. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Numerical Study of Evaporation and Motion Characteristics of Liquid Nitrogen Droplet in High-Speed Gas Flow

    Science.gov (United States)

    Ruan, Y.; Chen, L.; Liu, X.; Chen, S.; Hou, Y.

    2017-12-01

    In the cryogenic wind tunnel, cooling the circulating gas to cryogenic temperature by spraying liquid nitrogen (LN2) is an efficient way to increase the Reynolds number. The evaporation and motion of LN2 droplets in the high-speed gas flow is the critical process that determines the cooling rate, cooling capacity and the safe operation of the down-stream compressor. In this study, a numerical model of droplet motion and evaporation in high-speed gas flow is developed and verified against experimental data. The droplet evaporation rate, diameter and velocity are obtained during the evaporation process under different gas temperatures and flow velocities. The results show that the gas temperature has dominant influence on the droplet evaporation rate. High flow speed can increase droplet evaporation effectively at the beginning process. Evaporation of droplets with different diameters follows a similar trend. The absolute evaporation rate increases with the increase of droplet diameter while the relative evaporation amount is highest for the smallest droplet due to its high area-volume ratio. This numerical study provides insight for understanding the evaporation of LN2 droplets in high-speed gas flow and useful guidelines for the design of LN2 spray cooling.

  10. Misting-cooling systems for microclimatic control in public space

    OpenAIRE

    Nunes, Joao; Zoilo, Inaki; Jacinto, Nuno; Nunes, Ana; Torres-Campos, Tiago; Pacheco, Manuel; Fonseca, David

    2011-01-01

    Misting-cooling systems have been used in outdoor spaces mainly for aesthetic purposes, and punctual cooling achievement. However, they can be highly effective in outdoor spaces’ bioclimatic comfort, in terms of microclimatic control, as an evaporative cooling system. Recent concerns in increasing bioclimatic standards in public outdoor spaces, along with more sustainable practices, gave origin to reasoning where plastic principles are combined with the study of cooling efficacy, in order to ...

  11. Water Membrane Evaporator

    Science.gov (United States)

    Ungar, Eugene K.; Almlie, Jay C.

    2010-01-01

    A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

  12. Desiccant Enhanced Evaporative Air-Conditioning (DEVap): Evaluation of a New Concept in Ultra Efficient Air Conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, E.; Woods, J.; Burch, J.; Boranian, A.; Merrigan, T.

    2011-01-01

    NREL has developed the novel concept of a desiccant enhanced evaporative air conditioner (DEVap) with the objective of combining the benefits of liquid desiccant and evaporative cooling technologies into an innovative 'cooling core.' Liquid desiccant technologies have extraordinary dehumidification potential, but require an efficient cooling sink. DEVap's thermodynamic potential overcomes many shortcomings of standard refrigeration-based direct expansion cooling. DEVap decouples cooling and dehumidification performance, which results in independent temperature and humidity control. The energy input is largely switched away from electricity to low-grade thermal energy that can be sourced from fuels such as natural gas, waste heat, solar, or biofuels.

  13. Ventilative Cooling

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; Kolokotroni, Maria

    -of-the-art of ventilative cooling potentials and limitations, its consideration in current energy performance regulations, available building components and control strategies and analysis methods and tools. In addition, the report provides twenty six examples of operational buildings using ventilative cooling ranging from...

  14. INVESTIGATIONS ON LOW TEMPERATURE FLASH EVAPORATION DESALINATION FOR SMALL-SCALE APPLICATIONS

    OpenAIRE

    G. Jims John Wessley; P. Koshy Mathews

    2013-01-01

    This paper presents the experimental study of a flash evaporation based desalination system that can cater to the small-scale fresh water needs of coastal and arid areas. The proposed small-scalesystem consists of an evaporator, water-cooled condenser and a vacuum pump to produce the required vacuum in the evaporator. The effect of inlet brine water temperature at various flow rate and evaporator pressure on the fresh water yield is evaluated. A maximum fresh water yield of 4 l/h is obtained ...

  15. Evaporation and Antievaporation Instabilities

    Directory of Open Access Journals (Sweden)

    Andrea Addazi

    2017-10-01

    Full Text Available We review (antievaporation phenomena within the context of quantum gravity and extended theories of gravity. The (antievaporation effect is an instability of the black hole horizon discovered in many different scenarios: quantum dilaton-gravity, f ( R -gravity, f ( T -gravity, string-inspired black holes, and brane-world cosmology. Evaporating and antievaporating black holes seem to have completely different thermodynamical features compared to standard semiclassical black holes. The purpose of this review is to provide an introduction to conceptual and technical aspects of (antievaporation effects, while discussing problems that are still open.

  16. Active and passive cooling methods for dwellings

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan; Østergaard, Poul Alberg

    2018-01-01

    studies or with a simulation modelling, an assessment of temperature drop of each cooling method within a standard-size dwelling is carried out. Also, a comparison of initial investment, energy consumption, maintenance, retrofitting and required space is done. Thereafter, with this information, a decision...... ventilation, controlled ventilation, roof coating and eco-evaporative cooling are the most suitable passive methods for an extensive use in this country....

  17. Heat pump system with selective space cooling

    Science.gov (United States)

    Pendergrass, J.C.

    1997-05-13

    A reversible heat pump provides multiple heating and cooling modes and includes a compressor, an evaporator and heat exchanger all interconnected and charged with refrigerant fluid. The heat exchanger includes tanks connected in series to the water supply and a condenser feed line with heat transfer sections connected in counterflow relationship. The heat pump has an accumulator and suction line for the refrigerant fluid upstream of the compressor. Sub-cool transfer tubes associated with the accumulator/suction line reclaim a portion of the heat from the heat exchanger. A reversing valve switches between heating/cooling modes. A first bypass is operative to direct the refrigerant fluid around the sub-cool transfer tubes in the space cooling only mode and during which an expansion valve is utilized upstream of the evaporator/indoor coil. A second bypass is provided around the expansion valve. A programmable microprocessor activates the first bypass in the cooling only mode and deactivates the second bypass, and vice-versa in the multiple heating modes for said heat exchanger. In the heating modes, the evaporator may include an auxiliary outdoor coil for direct supplemental heat dissipation into ambient air. In the multiple heating modes, the condensed refrigerant fluid is regulated by a flow control valve. 4 figs.

  18. Heat pump system with selective space cooling

    Science.gov (United States)

    Pendergrass, Joseph C.

    1997-01-01

    A reversible heat pump provides multiple heating and cooling modes and includes a compressor, an evaporator and heat exchanger all interconnected and charged with refrigerant fluid. The heat exchanger includes tanks connected in series to the water supply and a condenser feed line with heat transfer sections connected in counterflow relationship. The heat pump has an accumulator and suction line for the refrigerant fluid upstream of the compressor. Sub-cool transfer tubes associated with the accumulator/suction line reclaim a portion of the heat from the heat exchanger. A reversing valve switches between heating/cooling modes. A first bypass is operative to direct the refrigerant fluid around the sub-cool transfer tubes in the space cooling only mode and during which an expansion valve is utilized upstream of the evaporator/indoor coil. A second bypass is provided around the expansion valve. A programmable microprocessor activates the first bypass in the cooling only mode and deactivates the second bypass, and vice-versa in the multiple heating modes for said heat exchanger. In the heating modes, the evaporator may include an auxiliary outdoor coil for direct supplemental heat dissipation into ambient air. In the multiple heating modes, the condensed refrigerant fluid is regulated by a flow control valve.

  19. mathematical model for direct evaporative space cooling systems

    African Journals Online (AJOL)

    eobe

    OF TECHNOLOGY AKURE,P.M.B. 704 AKURE, NIGERIA. .... Nigerian Journal of Technology (NIJOTECH). Vol. 32. No. 3. November ... pad, porous ceramic pad, wood shaven, jute, rice straw ..... A novel air conditioning system membrane air.

  20. Effects of disinfection, packaging and evaporatively cooled storage ...

    African Journals Online (AJOL)

    Similarly, disinfection treatment significantly (P 0.01) affected the changes in reducing, non-reducing and total sugars of mangoes during storage. Two-way interactions were significant (P 0.01) in terms of the changes in sugar content of mangoes. The benefits of the combined effect of post-harvest treatments on mangoes ...

  1. performance evaluation of a composite-padded evaporative cooling

    African Journals Online (AJOL)

    user

    are processed into other forms. These products consist mainly of water; hence without adequate storage after harvest, they shrivel, wither or rot away rapidly, particularly under hot tropical conditions due to loss of moisture, change in composition and pathological attack. [3-4]. In order to maintain freshness in these products,.

  2. Simple evaporative cooling method reduces bacterial content of ...

    African Journals Online (AJOL)

    African Journal of Food, Agriculture, Nutrition and Development. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 13, No 1 (2013) >. Log in or Register to get access to full text downloads.

  3. Simple evaporative cooling method reduces bacterial content of ...

    African Journals Online (AJOL)

    Effects of milk container placement during transport, treatment, and time on milk attributes were assessed using an analysis of variance for a randomized complete block design, with blocks based on eight instances of milk being transported to market. A factorial treatment structure also incorporated time as a repeated ...

  4. modeling of evaporation modeling of evaporation losses in sewage ...

    African Journals Online (AJOL)

    eobe

    A model for evaporation losses in sewage sludge drying bed was derived from first principles. This model was developed based on the reasoning that the rate at which evaporation is taking place is directly proportional to the instantaneous quantity of water in the sludge. The aim of this work was to develop a model to.

  5. Misting cooling technique for protected culture of Oncidium orchids ...

    African Journals Online (AJOL)

    The cooling technique can keep the interior air temperature lower than that of outside air temperature. The temperature of plants could be maintained close to the greenhouse air temperature. The intermittent misting function with the best evaporative cooling efficiency was controlled with interval operation. This technique ...

  6. Cooling devices and methods for use with electric submersible pumps

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Todd Andrew; Gamboa, Jose A

    2017-10-25

    Cooling devices for use with electric submersible pump motors include a refrigerator attached to the end of the electric submersible pump motor with the evaporator heat exchanger accepting all or a portion of the heat load from the motor. The cooling device can be a self-contained bolt-on unit, so that minimal design changes to existing motors are required.

  7. Cooling devices and methods for use with electric submersible pumps

    Science.gov (United States)

    Jankowski, Todd A; Hill, Dallas D

    2014-12-02

    Cooling devices for use with electric submersible pump motors include a refrigerator attached to the end of the electric submersible pump motor with the evaporator heat exchanger accepting all or a portion of the heat load from the motor. The cooling device can be a self-contained bolt-on unit, so that minimal design changes to existing motors are required.

  8. Evaluation of evaporation coefficient for micro-droplets exposed to low pressure: A semi-analytical approach

    Science.gov (United States)

    Chakraborty, Prodyut R.; Hiremath, Kirankumar R.; Sharma, Manvendra

    2017-02-01

    Evaporation rate of water is strongly influenced by energy barrier due to molecular collision and heat transfer limitations. The evaporation coefficient, defined as the ratio of experimentally measured evaporation rate to that maximum possible theoretical limit, varies over a conflicting three orders of magnitude. In the present work, a semi-analytical transient heat diffusion model of droplet evaporation is developed considering the effect of change in droplet size due to evaporation from its surface, when the droplet is injected into vacuum. Negligible effect of droplet size reduction due to evaporation on cooling rate is found to be true. However, the evaporation coefficient is found to approach theoretical limit of unity, when the droplet radius is less than that of mean free path of vapor molecules on droplet surface contrary to the reported theoretical predictions. Evaporation coefficient was found to reduce rapidly when the droplet under consideration has a radius larger than the mean free path of evaporating molecules, confirming the molecular collision barrier to evaporation rate. The trend of change in evaporation coefficient with increasing droplet size predicted by the proposed model will facilitate obtaining functional relation of evaporation coefficient with droplet size, and can be used for benchmarking the interaction between multiple droplets during evaporation in vacuum.

  9. Evaluation of evaporation coefficient for micro-droplets exposed to low pressure: A semi-analytical approach

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Prodyut R., E-mail: pchakraborty@iitj.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Jodhpur, 342011 (India); Hiremath, Kirankumar R., E-mail: k.r.hiremath@iitj.ac.in [Department of Mathematics, Indian Institute of Technology Jodhpur, 342011 (India); Sharma, Manvendra, E-mail: PG201283003@iitj.ac.in [Defence Laboratory Jodhpur, Defence Research & Development Organisation, 342011 (India)

    2017-02-05

    Evaporation rate of water is strongly influenced by energy barrier due to molecular collision and heat transfer limitations. The evaporation coefficient, defined as the ratio of experimentally measured evaporation rate to that maximum possible theoretical limit, varies over a conflicting three orders of magnitude. In the present work, a semi-analytical transient heat diffusion model of droplet evaporation is developed considering the effect of change in droplet size due to evaporation from its surface, when the droplet is injected into vacuum. Negligible effect of droplet size reduction due to evaporation on cooling rate is found to be true. However, the evaporation coefficient is found to approach theoretical limit of unity, when the droplet radius is less than that of mean free path of vapor molecules on droplet surface contrary to the reported theoretical predictions. Evaporation coefficient was found to reduce rapidly when the droplet under consideration has a radius larger than the mean free path of evaporating molecules, confirming the molecular collision barrier to evaporation rate. The trend of change in evaporation coefficient with increasing droplet size predicted by the proposed model will facilitate obtaining functional relation of evaporation coefficient with droplet size, and can be used for benchmarking the interaction between multiple droplets during evaporation in vacuum.

  10. Flow Boiling Pressure Drop and Heat Transfer of Refrigerants in Multi-microchannel Evaporators under Steady and Transient States

    OpenAIRE

    Huang, Houxue

    2016-01-01

    Multi-microchannel evaporators used for the cooling of high heat flux electronics have been of interest to both industry and academia for more than a decade. Such interest has sparked a large number of research studies on the flow boiling pressure drop and heat transfer in multi-microchannel evaporators. However, there are still several aspects that need to be addressed in order to better understand the complicated flow boiling process taking place in such micro-evaporators. Firstly, the me...

  11. CO2 cooling for HEP experiments

    CERN Document Server

    Verlaat; Van Lysebetten, A

    2008-01-01

    The new generation silicon detectors require more efficient cooling of the front-end electronics and the silicon sensors themselves. To minimize reverse annealing of the silicon sensors the cooling temperatures need to be reduced. Other important requirements of the new generation cooling systems are a reduced mass and a maintenance free operation of the hardware inside the detector. Evaporative CO2 cooling systems are ideal for this purpose as they need smaller tubes than conventional systems. The heat transfer capability of evaporative CO2 is high. CO2 is used as cooling fluid for the LHCb-VELO and the AMS-Tracker cooling systems. A special method for the fluid circulation is developed at Nikhef to get a very stable temperature of both detectors without any active components like valves or heaters inside. This method is called 2-phase Accumulator Controlled Loop (2PACL) and is a good candidate technology for the design of the future cooling systems for the Atlas and CMS upgrades.

  12. Lake Evaporation: a Model Study

    Science.gov (United States)

    Amayreh, Jumah Ahmad

    1995-01-01

    Reliable evaporation data are an essential requirement in any water and/or energy budget studies. This includes operation and management of both urban and agricultural water resources. Evaporation from large, open water surfaces such as lakes and reservoirs may influence many agricultural and irrigation decisions. In this study evaporation from Bear Lake in the states of Idaho and Utah was measured using advanced research instruments (Bowen Ratio and Eddy Correlation). Actual over-lake evaporation and weather data measurements were used to understand the mechanism of evaporation in the lake, determine lake-related parameters (such as roughness lengths, heat storage, net radiation, etc.), and examine and evaluate existing lake evaporation methods. This enabled the development of a modified and flexible model incorporating the tested methods for hourly and daily best estimates of lake evaporation using nearby simple land-based weather data and, if available, remotely sensed data. Average evaporation from Bear Lake was about 2 mm/day during the summer season (March-October) of this two-year (1993-1994) study. This value reflects the large amount of energy consumed in heating the water body of the lake. Moreover, evaporation from the lake was not directly related to solar radiation. This observation was clear during night time when the evaporation continued with almost the same rate as daytime evaporation. This explains the vital role of heat storage in the lake as the main driving energy for evaporation during night time and day time cloudy sky conditions. When comparing over-lake and nearby land-based weather parameters, land-based wind speed was the only weather parameter that had a significant difference of about 50% lower than over-lake measurements. Other weather parameters were quite similar. The study showed that evaporation from the lake can be accurately estimated using Penman-type equations if related parameters such as net radiation, heat storage, and

  13. Multileg Heat-Pipe Evaporator

    Science.gov (United States)

    Alario, J. P.; Haslett, R. A.

    1986-01-01

    Parallel pipes provide high heat flow from small heat exchanger. Six parallel heat pipes extract heat from overlying heat exchanger, forming evaporator. Vapor channel in pipe contains wick that extends into screen tube in liquid channel. Rods in each channel hold wick and screen tube in place. Evaporator compact rather than extended and more compatible with existing heat-exchanger geometries. Prototype six-pipe evaporator only 0.3 m wide and 0.71 m long. With ammonia as working fluid, transports heat to finned condenser at rate of 1,200 W.

  14. A very cool cooling system

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    The NA62 Gigatracker is a jewel of technology: its sensor, which delivers the time of the crossing particles with a precision of less than 200 picoseconds (better than similar LHC detectors), has a cooling system that might become the precursor to a completely new detector technique.   The 115 metre long vacuum tank of the NA62 experiment. The NA62 Gigatracker (GTK) is composed of a set of three innovative silicon pixel detectors, whose job is to measure the arrival time and the position of the incoming beam particles. Installed in the heart of the NA62 detector, the silicon sensors are cooled down (to about -20 degrees Celsius) by a microfluidic silicon device. “The cooling system is needed to remove the heat produced by the readout chips the silicon sensor is bonded to,” explains Alessandro Mapelli, microsystems engineer working in the Physics department. “For the NA62 Gigatracker we have designed a cooling plate on top of which both the silicon sensor and the...

  15. Evaporation of lead and lithium from molten Pb-17Li - transport of aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Feuerstein, H.; Graebner, H.; Oschinski, J.; Horn, S.; Bender, S. (Kernforschungszentrum Karlsruhe GmbH (Germany))

    1991-12-01

    Evaporation of Pb and Li from molten Pb-17Li was investigated between 350 and 800deg C in vacuum, argon and helium covergas. Results were also obtained from other experimental facilities. Similarities were found to observations from sodium cooled reactors. The results show that Pb and Li evaporate independent on each other. The two elements show different behavior along the transport pathway. Deposits of the evaporated metals contained between 0.2 and 98 at% Li. As in the reactor RAPSODIE for sodium, evaporation rates for lithium were smaller in helium than in argon, however evaporation rates of lead were the same in both gases. No aerosol problems will exist with normal blanket operation. Under experimental conditions, aerosol concentrations were in the range of 10{sup -9} to 10{sup -6} g/m{sup 3}. Aerosols can easily be trapped with sintered metal filters. (orig.).

  16. The effect of evaporator operating parameters on the flow patterns inside horizontal pipes

    Science.gov (United States)

    Tong, Lige; Li, Haiyan; Wang, Li; Sun, Xinxing; Xie, Yunfei

    2011-08-01

    A general and simple model for simulating the steady state behaviors of air-to-refrigerant fin-and-tube evaporator is introduced with the focus on the detailed flow patterns inside the tubes. In order to simulate the heat transfer between air and the working fluid, the evaporator is divided into a number of control volumes. Empirical correlations from literature were also adopted to estimate the void fraction, the internal and external heat transfer coefficients, and the pressure drops. Simulations were performed to study the effects of varying inlet air temperature, refrigerant mass flow rate and evaporation pressure on the flow patterns inside the horizontal pipe of the evaporator. The simulation results indicate that the proposed model can be used to predict flow patterns well. The predicted results of the model agree well with experimental results, the difference is within ±3% for the cooling capacity, and is within ±0.2% for refrigerant evaporation temperature.

  17. Displacement ventilation and passive cooling strategies

    Energy Technology Data Exchange (ETDEWEB)

    Carew, P.; Bekker, B. [PJCarew Consulting, Cape Town (South Africa)

    2009-07-01

    Displacement ventilation (DV) is widely used a passive cooling strategy because it requires less air supply for cooling compared to conventional mixing ventilation (MV). DV introduces air at low level and low velocity, and at high supply air temperature, usually around 18 degrees C. The slightly cooler air runs along the floor of a room until it reaches a heat load. The heat load induces a plume of warmer air that rises due to lower density. This induces stratification in room temperature with the occupied area of the room. The air near the ceiling is continually exhausted to prevent a build up of warm air into the occupied zone. This paper demonstrated the impacts of using DV in comparison to MV on the peak capacity, size and humidity levels associated with various passive cooling strategies, informed by the ASHRAE DV guidelines. A generic office building in Johannesburg, South Africa, was used as a model. The paper illustrated the extent to which DV can be used as a passive cooling strategy in spaces that were previously considered as having too high a heat load when calculated using MV system guidelines. A comparison of DV and MV also highlighted the risk of over-design when conventional MV guidelines are used to design cooling sources for DV applications. The DV was shown to significantly lower the amount of supply air needed to serve a room's heat load when compared to MV at the same temperatures. This reduction in air supply impacts the feasibility of using passive cooling strategies in evaporative cooling, 2-stage evaporative cooling, thermal storage and air to ground heat exchangers. However, passive cooling strategies are unlikely to be widely implemented until design guidelines are created by organizations such as ASHRAE. 8 refs., 2 tabs., 15 figs.

  18. Lake Nasser evaporation reduction study

    Directory of Open Access Journals (Sweden)

    Hala M.I. Ebaid

    2010-10-01

    Full Text Available This study aims to evaluate the reduction of evaporation of Lake Nasser’s water caused by disconnecting (fully or partially some of its secondary channels (khors. This evaluation integrates remote sensing, Geographic Information System (GIS techniques, aerodynamic principles, and Landsat7 ETM+ images. Three main procedures were carried out in this study; the first derived the surface temperature from Landsat thermal band; the second derived evaporation depth and approximate evaporation volume for the entire lake, and quantified evaporation loss to the secondary channels’ level over one month (March by applied aerodynamic principles on surface temperature of the raster data; the third procedure applied GIS suitability analysis to determine which of these secondary channels (khors should be disconnected. The results showed evaporation depth ranging from 2.73 mm/day at the middle of the lake to 9.58 mm/day at the edge. The evaporated water-loss value throughout the entire lake was about 0.86 billion m3/month (March. The analysis suggests that it is possible to save an approximate total evaporation volume loss of 19.7 million m3/month (March, and thus 2.4 billion m3/year, by disconnecting two khors with approximate construction heights of 8 m and 15 m. In conclusion, remote sensing and GIS are useful for applications in remote locations where field-based information is not readily available and thus recommended for decision makers remotely planning in water conservation and management.

  19. Experimental study on solar desiccant cooling system. 2nd Report; Taiyonetsu kudo desiccant cooling system no jikkenteki kento. 2

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, H.; Funato, H. [Fukuoka Institute of Technology, Fukuoka (Japan); Kuma, T. [Seibu Giken Co. Ltd., Fukuoka (Japan)

    1996-10-27

    Study has been made about a desiccant cleaning system using solar heated water for regenerating the dehumidifier. A dehumidifier and evaporation coolers are combined to attain a synergistic effect in dehumidifying and cooling the air in the house. The simultaneous control of humidity and temperature, however, is quite difficult. Under the circumstances, an evaporation cooler was removed from the outdoor air intake side, to leave a humidifier alone for the control of humidity only. In addition, the length of the dehumidifier was reduced into half for saving fan driving power and for downscaling the model. With only one evaporation cooler in operation that is installed at the exhaust side, the cooling effect is diminished by half. For dealing with the situation, ultrasonic atomization is performed at the exhaust side evaporation cooler for the improvement of the air cooling effect for the next sensible heat exchanger (intake side). The return air is heated by the solar heater water (approximately 60{degree}C hot), regenerates the dehumidifier, and then exhausted. The atomization process elevates the cooling effect, and the resultant cooling effect was as high as that expected from a 2-cooler setup. The dehumidification effect, however, lowers a little. Exclusion of the atomization process will enhance the dehumidification effect, but will reduce the cooling effect as well. 3 refs., 8 figs., 3 tabs.

  20. REACTOR COOLING

    Science.gov (United States)

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  1. Cool collapsible

    OpenAIRE

    Linnér, Fredrik

    2010-01-01

    Cool collabsible är ett projekt som har handlat om att skapa ett hopfällbart utomhusbord. Arbetet har utförts tillsammans med aka buna design consult. Projektet har fokuserats på att hitta en funktion, teknik och material för att sedan transformera detta till ett innovativt utomhusbord. Genom ett utförligt arbete med att definiera målgruppen skapades ramar som format ett bord till den typiska brukaren. Resultatet blev ett hopfällbart bord som hämtat sin inspiration från naturen. Ett bord som ...

  2. Modelling hourly rates of evaporation from small lakes

    Directory of Open Access Journals (Sweden)

    R. J. Granger

    2011-01-01

    Full Text Available The paper presents the results of a field study of open water evaporation carried out on three small lakes in Western and Northern Canada. In this case small lakes are defined as those for which the temperature above the water surface is governed by the upwind land surface conditions; that is, a continuous boundary layer exists over the lake, and large-scale atmospheric effects such as entrainment do not come into play. Lake evaporation was measured directly using eddy covariance equipment; profiles of wind speed, air temperature and humidity were also obtained over the water surfaces. Observations were made as well over the upwind land surface.

    The major factors controlling open water evaporation were examined. The study showed that for time periods shorter than daily, the open water evaporation bears no relationship to the net radiation; the wind speed is the most significant factor governing the evaporation rates, followed by the land-water temperature contrast and the land-water vapour pressure contrast. The effect of the stability on the wind field was demonstrated; relationships were developed relating the land-water wind speed contrast to the land-water temperature contrast. The open water period can be separated into two distinct evaporative regimes: the warming period in the Spring, when the land is warmer than the water, the turbulent fluxes over water are suppressed; and the cooling period, when the water is warmer than the land, the turbulent fluxes over water are enhanced.

    Relationships were developed between the hourly rates of lake evaporation and the following significant variables and parameters (wind speed, land-lake temperature and humidity contrasts, and the downwind distance from shore. The result is a relatively simple versatile model for estimating the hourly lake evaporation rates. The model was tested using two independent data sets. Results show that the modelled evaporation follows the observed values

  3. Assessment of the Multi-Fluid Evaporator Technology

    Science.gov (United States)

    Quinn, Gregory; O'Connor, Edward

    2008-01-01

    Hamilton Sundstrand has developed a scalable evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It was designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used as a heat sink from Earth sea level conditions to the vacuum of space. The current shuttle configuration utilizes an ammonia boiler and water based flash evaporator system to achieve cooling at all altitudes. This system combines both functions into a single compact package with improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. A full-scale system uses multiple core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A single-core MFE engineering development unit (EDU) was built in 2006, followed by a full scale, four-core prototype in 2007. The EDU underwent extensive thermal testing while the prototype was being built. Lessons learned from the EDU were incorporated into the prototype and proven out in check-out testing. The EDU and prototype testing proved out the MFE's ability to passively control back-pressure, avoid unwanted icing, tolerate icing if it should occur, provide a three-to-one turn down ratio in heat load and scale up efficiently. Some issues with these first designs of the MFE have limited its ability to reject heat without liquid evaporant carry-over. However, they are due to the implementation of the design rather than the fundamentals of the technology. This paper discusses the background, development and present state of the Multi-Fluid Evaporator technology and concludes with efforts underway to advance the state-of-the-art.

  4. The ATLAS IBL CO2 Cooling System

    CERN Document Server

    Verlaat, Bartholomeus; The ATLAS collaboration

    2016-01-01

    The Atlas Pixel detector has been equipped with an extra B-layer in the space obtained by a reduced beam pipe. This new pixel detector called the ATLAS Insertable B-Layer (IBL) is installed in 2014 and is operational in the current ATLAS data taking. The IBL detector is cooled with evaporative CO2 and is the first of its kind in ATLAS. The ATLAS IBL CO2 cooling system is designed for lower temperature operation (<-35⁰C) than the previous developed CO2 cooling systems in High Energy Physics experiments. The cold temperatures are required to protect the pixel sensors for the high expected radiation dose up to 550 fb^-1 integrated luminosity. This paper describes the design, development, construction and commissioning of the IBL CO2 cooling system. It describes the challenges overcome and the important lessons learned for the development of future systems which are now under design for the Phase-II upgrade detectors.

  5. Alternatives to compressor cooling in California climates

    Energy Technology Data Exchange (ETDEWEB)

    Feustel, H. (Lawrence Berkeley Lab., CA (United States)); de Almeida, A. (Coimbra Univ. (Portugal). Dept. of Electrical Engineering); Blumstein, C. (California Univ., Berkeley, CA (United States). Universitywide Energy Research Group)

    1991-01-01

    This review and discussion has been prepared for the California Institute for Energy Efficiency (CIEE) to examine research on alternatives to compressor cooling. The report focuses on strategies for eliminating compressors in California's transition climates -- moderately warm areas located between the cool coastal regions and the hot central regions. Many of these strategies could also help reduce compressor use in hotter climates. Compressor-driven cooling of residences in California's transition climate regions is an undesirable load for California's electric utilities because load factor is poor and usage is typically high during periods of system peak demand. We review a number of alternatives to compressors, including low-energy strategies: evaporative cooling, natural and induced ventilation, reflective coatings, shading with vegetation and improved glazing, thermal storage, and radiative cooling. Also included are two energy-intensive strategies: absorption cooling and desiccant cooling. Our literature survey leads us to conclude that many of these strategies, used either singly or in combination, are technically and economically feasible alternatives to compressor-driven cooling. 78 refs., 8 figs.

  6. Intermitência do sistema de resfriamento adiabático evaporativo por aspersão em instalação para vacas em lactação Sprinkling frequency of adiabatic evaporative cooling system in dairy cow housing

    Directory of Open Access Journals (Sweden)

    Soraia V. Matarazzo

    2006-12-01

    Full Text Available Teve-se o objetivo de avaliar o período de intermitência de acionamento do sistema de resfriamento adiabático evaporativo (SRAE por aspersão na linha de alimentação, em instalação do tipo freestall e sua influência no conforto térmico de vacas em lactação. Foram utilizadas 12 vacas multíparas com produção média de 30 kg de leite por dia. Os tratamentos corresponderam às intermitências de 12; 14 e 16 min, e os dados referentes à temperatura do bulbo seco (TBS, umidade relativa do ar (UR e temperatura de globo negro (TGN, no interior da instalação e no ambiente externo, foram mensurados ao longo das 24 h durante todo o período experimental. A freqüência respiratória (FR, temperatura retal (TR e temperatura do pelame (TP foram medidas às 13; 14; 15 e 16 h em todos os animais. As variáveis meteorológicas TBS (31,5 ºC, TGN (32,5 ºC e os índices de conforto térmico ITU (79,0 e ITGU (81,0 foram maiores na intermitência de 12 min quando comparados aos demais tratamentos. A UR mostrou-se mais elevada no tratamento de 14 min (60,3% em relação à intermitência de 12 min (51,0%. Verificou-se que as vacas em lactação expostas à intermitência de 12 min apresentaram maior valor de TR (39,1 ºC e FR (76,0 mov min-1 quando comparado aos tratamentos de 14 e 16 min. As intermitências de 14 e 16 min proporcionaram condições ambientais semelhantes e menores valores de TR, FR e TP, mostrando-se eficientes na redução do estresse térmico de vacas em lactação. O intervalo de 16 min empregou menor quantidade de água, podendo ser adotado a fim de evitar desperdícios desnecessários pelo sistema de resfriamento adiabático evaporativo.This work aimed to evaluate the effect of sprinkling frequency of adiabatic evaporative cooling system within feed line of a freestall in relation to temperature and humidity index (THI,black globe temperature index (BGHI and physiological responses in dairy cows. There were used twelve

  7. MULTIFUNCTIONAL SOLAR SYSTEMS FOR HEATING AND COOLING

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2010-12-01

    Full Text Available The basic circuits of multifunctional solar systems of air drainage, heating (hot water supply and heating, cooling and air conditioning are developed on the basis of open absorption cycle with a direct absorbent regeneration. Basic decisions for new generation of gas-liquid solar collectors are developed. Heat-mass-transfer apparatus included in evaporative cooling system, are based on film interaction of flows of gas and liquid and in them, for the creation of nozzle, multi-channel structures from polymeric materials and porous ceramics are used. Preliminary analysis of multifunctional systems possibilities is implemented.

  8. Water Evaporation in Swimming Baths

    DEFF Research Database (Denmark)

    Hyldgård, Carl-Erik

    This paper is publishing measuring results from models and full-scale baths of the evaporation in swimming baths, both public baths and retraining baths. Moreover, the heat balance of the basin water is measured. In addition the full-scale measurements have given many experiences which are repres......This paper is publishing measuring results from models and full-scale baths of the evaporation in swimming baths, both public baths and retraining baths. Moreover, the heat balance of the basin water is measured. In addition the full-scale measurements have given many experiences which...

  9. Energy storage in evaporated brine

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, R. Ian

    2010-09-15

    We propose storage of electrical energy in brine solutions by using the energy to enhance natural evaporation. Using properties of existing industrial evaporation technologies and estimates of power regeneration from brine by pressure retarded osmosis, efficiency near 100% is calculated. Modelling indicates that systems ranging from 50kW to 50MW output may be practical, with storage capacities of hours to days. The method appears to have potential to be economically competitive with other technologies over a wide range of capacity. It may present a large new application area that could aid the development of salinity-based power generation technology.

  10. modeling of evaporation modeling of evaporation losses in sewage

    African Journals Online (AJOL)

    eobe

    advance treatment. This shall be the task of sludge drying process, understood as thermal drying process in which thermal energy is delivered to the sludge in order to evaporate water [5].The exchange of mass and heat between dried sludge and air (material and. Nigerian Journal of Technology (NIJOTECH). Vol. 34 No.

  11. Using Historical Precipitation, Temperature, and Runoff Observations to Evaluate Evaporation Formulations in Land Surface Models

    Science.gov (United States)

    Koster, Randal D.; Mahanama, P. P.

    2012-01-01

    Key to translating soil moisture memory into subseasonal precipitation and air temperature forecast skill is a realistic treatment of evaporation in the forecast system used - in particular, a realistic treatment of how evaporation responds to variations in soil moisture. The inherent soil moisture-evaporation relationships used in today's land surface models (LSMs), however, arguably reflect little more than guesswork given the lack of evaporation and soil moisture data at the spatial scales represented by regional and global models. Here we present a new approach for evaluating this critical aspect of LSMs. Seasonally averaged precipitation is used as a proxy for seasonally-averaged soil moisture, and seasonally-averaged air temperature is used as a proxy for seasonally-averaged evaporation (e.g., more evaporative cooling leads to cooler temperatures) the relationship between historical precipitation and temperature measurements accordingly mimics in certain important ways nature's relationship between soil moisture and evaporation. Additional information on the relationship is gleaned from joint analysis of precipitation and streamflow measurements. An experimental framework that utilizes these ideas to guide the development of an improved soil moisture-evaporation relationship is described and demonstrated.

  12. Iron isotopes in chondrules: Implications for the role of evaporation during chondrule formation

    Science.gov (United States)

    Alexander, C. M. O'd.; Wang, J.

    2001-03-01

    We have measured the ?57Fe of olivines in nine Chainpur chondrules. All are within error of normal (typically 2?=1-2=1). Most of the chondules could not have lost more than ~20% of their FeO by Rayleigh evaporation and none can have lost more than ~61%. Yet, the range of Fo contents in these chondrules is Fo78-Fo99.9. The isotopic compositions of the chondrules clearly demonstrate that, for instance, Type I chondrules cannot form from Type II chondrules by evaporation of FeO under Rayleigh conditions. The isotopic compositions also place constraints on the minimum cooling rates these chondrules could have experienced. These cooling rates must also be equal to or slower than those required to produce the chondrule textures. Assuming flash heating and evaporation rates like those measured in vacuum, the minimum cooling rates necessary to prevent detectable Fe isotopic fractionation via Rayleigh evaporation approach those needed to produce barred and porphyritic textures. The presence of hydrogen in the Nebula, non-linear cooling and other effects will all tend to increase the cooling rates required to prevent ?57Fe>1-2=1, perhaps by as much as 1-2 orders of magnitude. The two most likely ways that the cooling rates required to prevent ?57Fe>1-2=1 can be kept below those needed to produce barred and porphyritic textures are: (1) the pH2 in the Nebula was low enough to keep evaporation rates close to those in vacuum, or (2) back reaction of chondrules with Fe in the gas suppressed isotopic fractionation.

  13. Cool visitors

    CERN Document Server

    2006-01-01

    Pictured, from left to right: Tim Izo (saxophone, flute, guitar), Bobby Grant (tour manager), George Pajon (guitar). What do the LHC and a world-famous hip-hop group have in common? They are cool! On Saturday, 1st July, before their appearance at the Montreux Jazz Festival, three members of the 'Black Eyed Peas' came on a surprise visit to CERN, inspired by Dan Brown's Angels and Demons. At short notice, Connie Potter (Head of the ATLAS secretariat) organized a guided tour of ATLAS and the AD 'antimatter factory'. Still curious, lead vocalist Will.I.Am met CERN physicist Rolf Landua after the concert to ask many more questions on particles, CERN, and the origin of the Universe.

  14. Cool Snacks

    DEFF Research Database (Denmark)

    Krogager, Stinne Gunder Strøm; Grunert, Klaus G; Brunsø, Karen

    2016-01-01

    Young people snack and their snacking habits are not always healthy. We address the questions whether it is possible to develop a new snack product that adolescents will find attractive, even though it is based on ingredients as healthy as fruits and vegetables, and we argue that developing...... such a product requires an interdisciplinary effort where researchers with backgrounds in psychology, anthropology, media science, philosophy, sensory science and food science join forces. We present the COOL SNACKS project, where such a blend of competences was used first to obtain thorough insight into young...... people's snacking behaviour and then to develop and test new, healthier snacking solutions. These new snacking solutions were tested and found to be favourably accepted by young people. The paper therefore provides a proof of principle that the development of snacks that are both healthy and attractive...

  15. The sustainability of LNG evaporation

    NARCIS (Netherlands)

    Stougie, L.; Van der Kooi, H.J.

    2011-01-01

    Numerous LNG (Liquefied Natural Gas) import terminals are under construction to fulfil the growing demand for energy carriers. After storage in tanks, the LNG needs to be heated and evaporated, also called ‘regasified’, to the natural gas needed in households and industry. Several options exist for

  16. Spacesuit Water Membrane Evaporator Integration with the ISS Extravehicular Mobility

    Science.gov (United States)

    Margiott, Victoria; Boyle, Robert

    2014-01-01

    NASA has developed a Solid Water Membrane Evaporation (SWME) to provide cooling for the next generation spacesuit. One approach to increasing the TRL of the system is to incorporate this hardware with the existing EMU. Several integration issues were addressed to support a potential demonstration of the SWME with the existing EMU. Systems analysis was performed to assess the capability of the SWME to maintain crewmember cooling and comfort as a replacement for sublimation. The materials of the SWME were reviewed to address compatibility with the EMU. Conceptual system placement and integration with the EMU via an EVA umbilical system to ensure crew mobility and Airlock egress were performed. A concept of operation for EVA use was identified that is compatible with the existing system. This concept is extensible as a means to provide cooling for the existing EMU. The cooling system of one of the EMUs on orbit has degraded, with the root cause undetermined. Should there be a common cause resident on ISS, this integration could provide a means to recover cooling capability for EMUs on orbit.

  17. Experimental study of the transient regime behaviour of an refrigerating machine evaporator; Estudo experimental do comportamento em regime transiente de um evaporador de uma maquina frigorifica

    Energy Technology Data Exchange (ETDEWEB)

    Machado, L.; Outtagarts, A.; Haberschill, P.; Lallemand, M. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France). Centre de Thermique de Lyon

    1995-07-01

    The aim of this work is the experimental study of the dynamic behaviour of a refrigerating machine evaporator. The superheat and cooling capacity responses to step exciting inlet and outlet refrigerant flow rates have been analysed for different operating points of the machine. The responses analysis allowed to determine the variations laws of the evaporators characteristics (gain, time constant) versus the compressor speed and evaporation temperature. (author)

  18. Influence of the wall on the droplet evaporation

    Directory of Open Access Journals (Sweden)

    Misyura S. Y.

    2015-01-01

    Full Text Available Evaporative influence of the wall material and its thickness has been investigated in the present study. The wall influence for heat exchangers is particularly important in the boiling transition regime and in the event of the Leidenfrost temperature. The experimental points significantly diverge in the transition area of the boiling crisis. This fact can be explained by a different residence time of droplet on the wall surface. The discrepancy between the experimental data also takes place at the Leidenfrost temperature. The lower the thermal diffusivity of the wall material (high thermal inertia, the more the wall is cooled under a droplet.

  19. Testing of the Multi-Fluid Evaporator Engineering Development Unit

    Science.gov (United States)

    Quinn, Gregory; O'Connor, Ed; Riga, Ken; Anderson, Molly; Westheimer, David

    2007-01-01

    Hamilton Sundstrand is under contract with the NASA Johnson Space Center to develop a scalable, evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It is being designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used from Earth sea level conditions to the vacuum of space. The current Shuttle configuration utilizes an ammonia boiler and flash evaporator system to achieve cooling at all altitudes. The MFE system combines both functions into a single compact package with significant weight reduction and improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. The full scale MFE prototype will be constructed with four core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A sub-scale MFE engineering development unit (EDU) has been built, and is identical to one of the four sections of a full scale prototype. The EDU has completed testing at Hamilton Sundstrand. The overall test objective was to determine the thermal performance of the EDU. The first set of tests simulated how each of the four sections of the prototype would perform by varying the chamber pressure, evaporant flow rate, coolant flow rate and coolant temperature. A second set of tests was conducted with an outlet steam header in place to verify that the outlet steam orifices prevent freeze-up in the core while also allowing the desired thermal turn-down ratio. This paper discusses the EDU tests and results.

  20. High Performance Torso Cooling Garment

    Science.gov (United States)

    Conger, Bruce; Makinen, Janice

    2016-01-01

    The concept proposed in this paper is to improve thermal efficiencies of the liquid cooling and ventilation garment (LCVG) in the torso area, which could facilitate removal of LCVG tubing from the arms and legs, thereby increasing suited crew member mobility. EVA space suit mobility in micro-gravity is challenging, and it becomes even more challenging in the gravity of Mars. By using shaped water tubes that greatly increase the contact area with the skin in the torso region of the body, the heat transfer efficiency can be increased. This increase in efficiency could provide the required liquid cooling via torso tubing only; no arm or leg LCVG tubing would be required. Benefits of this approach include increased crewmember mobility, enhanced evaporation cooling, increased comfort during Mars EVA tasks, and easing of the overly dry condition in the helmet associated with the Advanced Extravehicular Mobility Unit (EMU) ventilation loop currently under development. This report describes analysis and test activities performed to evaluate the potential improvements to the thermal performance of the LCVG. Analyses evaluated potential tube shapes for improving the thermal performance of the LCVG. The analysis results fed into the selection of flat flow strips to improve thermal contact with the skin of the suited test subject. Testing of small segments was performed to compare thermal performance of the tubing approach of the current LCVG to the flat flow strips proposed as the new concept. Results of the testing is presented along with recommendations for future development of this new concept.

  1. Quantifying Evaporation in a Permeable Pavement System

    Science.gov (United States)

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  2. Detailed finite element method modeling of evaporating multi-component droplets

    Energy Technology Data Exchange (ETDEWEB)

    Diddens, Christian, E-mail: C.Diddens@tue.nl

    2017-07-01

    The evaporation of sessile multi-component droplets is modeled with an axisymmetic finite element method. The model comprises the coupled processes of mixture evaporation, multi-component flow with composition-dependent fluid properties and thermal effects. Based on representative examples of water–glycerol and water–ethanol droplets, regular and chaotic examples of solutal Marangoni flows are discussed. Furthermore, the relevance of the substrate thickness for the evaporative cooling of volatile binary mixture droplets is pointed out. It is shown how the evaporation of the more volatile component can drastically decrease the interface temperature, so that ambient vapor of the less volatile component condenses on the droplet. Finally, results of this model are compared with corresponding results of a lubrication theory model, showing that the application of lubrication theory can cause considerable errors even for moderate contact angles of 40°. - Graphical abstract:.

  3. Influence of Oil on Refrigerant Evaporator Performance

    Science.gov (United States)

    Kim, Jong-Soo; Nagata, Karsuya; Katsuta, Masafumi; Tomosugi, Hiroyuki; Kikuchi, Kouichiro; Horichi, Toshiaki

    In vapor compression refrigeration system using oil-lubricated compressors, some amount of oil is always circulated through the system. Oil circulation can have a significant influence on the evaporator performance of automotive air conditioner which is especially required to cool quickly the car interior after a period standing in the sun. An experimental investigation was carried out an electrically heated horizontal tube to measure local heat transfer coefficients for various flow rates and heat fluxes during forced convection boiling of pure refrigerant R12 and refrigerant-oil mixtures (0-11% oil concentration by weight) and the results were compared with oil free performance. Local heat transfer coefficients increased at the region of low vapor quality by the addition of oil. On the other hand, because the oil-rich liquid film was formed on the heat transfer surface, heat transfer coefficients gradually decreased as the vapor quality became higher. Average heat transfer coefficient reached a maximum at about 4% oil concentration and this trend agreed well with the results of Green and Furse. Previous correlations, using the properties of the refrigerant-oil mixture, could not predict satisfactorily the local heat transfer coefficients data. New correlation modified by oil concentration factor was developed for predicting the corresponding heat transfer coefficient for refrigerant-oil mixture convection boiling. The maximum percent deviation between predicted and measured heat transfer coefficient was within ±30%.

  4. Renewable Heating and Cooling

    Science.gov (United States)

    Renewable heating and cooling is a set of alternative resources and technologies that can be used in place of conventional heating and cooling technologies for common applications such as water heating, space heating, space cooling and process heat.

  5. Evaporation from a sphagnum moss surface

    Science.gov (United States)

    D.S. Nichols; J.M. Brown

    1980-01-01

    Peat cores, 45 cm in diameter, were collected from a sphagnum bog in northern Minnesota, and used to measure the effects of different temperatures and water levels on evaporation from a sphagnum moss surface in a growth chamber. Under all conditions, evaporation from the moss surface was greater than that from a free-water surface. Evaporation from the moss increased...

  6. Iodine retention during evaporative volume reduction

    Science.gov (United States)

    Godbee, H.W.; Cathers, G.I.; Blanco, R.E.

    1975-11-18

    An improved method for retaining radioactive iodine in aqueous waste solutions during volume reduction is disclosed. The method applies to evaporative volume reduction processes whereby the decontaminated (evaporated) water can be returned safely to the environment. The method generally comprises isotopically diluting the waste solution with a nonradioactive iodide and maintaining the solution at a high pH during evaporation.

  7. Effect of Precipitable Water Vapor Amount on Radiative Cooling Performance

    Science.gov (United States)

    Hu, Mingke; Zhao, Bin; Ao, Xianze; Pei, Gang

    2017-05-01

    A radiative cooler based on aluminum-evaporated polyvinyl-fluoride surface was employed to investigate the effect of precipitable water vapor amount on its radiative cooling performance. A mathematic model of steady heat transfer that considers the spectral radiant distribution of the sky, the transparent cover and the collecting surface was established. The results indicate that the amount of precipitable water vapor shows a remarkable and negative effect on radiative cooling performance of the radiative cooler. Both the temperature difference between the cooler and surroundings and the net radiative cooling power decrease as the precipitable water vapor amount increases. The net radiative cooling power drops by about 41.0% as the the precipitable water vapor amount changes from 1.0 cm to 7.0 cm. Besides, the radiative cooler shows better cooling performance in winter than in summer. The net radiative cooling power in summer of Hefei is about 82.2% of that in winter.

  8. Restaurant food cooling practices.

    Science.gov (United States)

    Brown, Laura Green; Ripley, Danny; Blade, Henry; Reimann, Dave; Everstine, Karen; Nicholas, Dave; Egan, Jessica; Koktavy, Nicole; Quilliam, Daniela N

    2012-12-01

    Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study.

  9. Spatiotemporal infrared measurement of interface temperatures during water droplet evaporation on a nonwetting substrate

    Science.gov (United States)

    Chandramohan, Aditya; Weibel, Justin A.; Garimella, Suresh V.

    2017-01-01

    High-fidelity experimental characterization of sessile droplet evaporation is required to understand the interdependent physical mechanisms that drive the evaporation. In particular, cooling of the interface due to release of the latent heat of evaporation, which is not accounted for in simplified vapor-diffusion-based models of droplet evaporation, may significantly suppress the evaporation rate on nonwetting substrates, which support tall droplet shapes. This suppression is counteracted by convective mass transfer from the droplet to the air. While prior numerical modeling studies have identified the importance of these mechanisms, there is no direct experimental evidence of their influence on the interfacial temperature distribution. Infrared thermography is used here to simultaneously measure the droplet volume, contact angle, and spatially resolved interface temperatures for water droplets on a nonwetting substrate. The technique is calibrated and validated to quantify the temperature measurement accuracy; a correction is employed to account for reflections from the surroundings when imaging the evaporating droplets. Spatiotemporally resolved interface temperature data, obtained via infrared thermography measurements, allow for an improved prediction of the evaporation rate and can be utilized to monitor temperature-controlled processes in droplets for various lab-on-a-chip applications.

  10. Preoperational test report, recirculation condenser cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, F.T.

    1997-11-04

    This represents a preoperational test report for Recirculation Condenser Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The four system provide condenser cooling water for vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102. Each system consists of a valved piping loop, a pair of redundant recirculation pumps, a closed-loop evaporative cooling tower, and supporting instrumentation; equipment is located outside the farm on concrete slabs. Piping is routed to the each ventilation condenser inside the farm via below-grade concrete trenches. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  11. Desiccant-assisted cooling fundamentals and applications

    CERN Document Server

    Brum, Nisio

    2014-01-01

    The increasing concern with indoor air quality has led to air-quality standards with increased ventilation rates. Although increasing the volume flow rate of outside air is advisable from the perspective of air-quality, it is detrimental to energy consumption, since the outside air has to be brought to the comfort condition before it is insufflated to the  conditioned ambient. Moreover, the humidity load carried within outside air has challenging HVAC engineers to design cooling units which are able to satisfactorily handle both sensible and latent contributions to the thermal load. This constitutes a favorable scenario for the use of solid desiccants to assist the cooling units. In fact, desiccant wheels have been increasingly applied by HVAC designers, allowing distinct processes for the air cooling and dehumidification. In fact, the ability of solid desiccants in moisture removal is effective enough to allow the use of evaporative coolers, in opposition to the traditional vapor-compression cycle, resultin...

  12. The ATLAS IBL CO2 Cooling System

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00237783; The ATLAS collaboration; Zwalinski, L.; Bortolin, C.; Vogt, S.; Godlewski, J.; Crespo-Lopez, O.; Van Overbeek, M.; Blaszcyk, T.

    2017-01-01

    The ATLAS Pixel detector has been equipped with an extra B-layer in the space obtained by a reduced beam pipe. This new pixel detector called the ATLAS Insertable B-Layer (IBL) is installed in 2014 and is operational in the current ATLAS data taking. The IBL detector is cooled with evaporative CO2 and is the first of its kind in ATLAS. The ATLAS IBL CO2 cooling system is designed for lower temperature operation (<-35⁰C) than the previous developed CO2 cooling systems in High Energy Physics experiments. The cold temperatures are required to protect the pixel sensors for the high expected radiation dose up to 550 fb^-1 integrated luminosity.

  13. Self-Cooling Gradient Shell for Body Armor

    Science.gov (United States)

    2012-05-10

    3 Figure 2. Reference (left) and Sample System (right) Arrangements Showing (a) the Styrofoam Insulation, (b...sweating hot plate [10]. It is designed to determine the thermal and evaporative resistance of materials producing numerical values for both...temperature and power gains in cooling systems. While this approach delivers reliable results, the high cost of the plate does not allow its widespread

  14. Solar-powered cooling system

    Science.gov (United States)

    Farmer, Joseph C.

    2015-07-28

    A solar-powered adsorption-desorption refrigeration and air conditioning system that uses nanostructural materials such as aerogels, zeolites, and sol gels as the adsorptive media. Refrigerant molecules are adsorbed on the high surface area of the nanostructural material while the material is at a relatively low temperature, perhaps at night. During daylight hours, when the nanostructural materials is heated by the sun, the refrigerant are thermally desorbed from the surface of the aerogel, thereby creating a pressurized gas phase in the vessel that contains the aerogel. This solar-driven pressurization forces the heated gaseous refrigerant through a condenser, followed by an expansion valve. In the condenser, heat is removed from the refrigerant, first by circulating air or water. Eventually, the cooled gaseous refrigerant expands isenthalpically through a throttle valve into an evaporator, in a fashion similar to that in more conventional vapor recompression systems.

  15. Determination of the Evaporation Coefficient of D2O

    Energy Technology Data Exchange (ETDEWEB)

    Drisdell, Walter S.; Cappa, Christopher D.; Smith, Jared D.; Saykally, Richard J.; Cohen, Ronald C.

    2008-03-26

    The evaporation rate of D{sub 2}O has been determined by Raman thermometry of a droplet train (12-15 {micro}m diameter) injected into vacuum ({approx}10{sup -5} torr). The cooling rate measured as a function of time in vacuum was fit to a model that accounts for temperature gradients between the surface and the core of the droplets, yielding an evaporation coefficient ({gamma}{sub e}) of 0.57 {+-} 0.06. This is nearly identical to that found for H{sub 2}O (0.62 {+-} 0.09) using the same experimental method and model, and indicates the existence of a kinetic barrier to evaporation. The application of a recently developed transition state theory (TST) model suggests that the kinetic barrier is due to librational and hindered translational motions at the liquid surface, and that the lack of an isotope effect is due to competing energetic and entropic factors. The implications of these results for cloud and aerosol particles in the atmosphere are discussed.

  16. Does evaporation paradox exist in China?

    Directory of Open Access Journals (Sweden)

    Z. T. Cong

    2009-03-01

    Full Text Available One expected consequence of global warming is the increase in evaporation. However, lots of observations show that the rate of evaporation from open pans of water has been steadily decreasing all over the world in the past 50 years. The contrast between expectation and observation is called "evaporation paradox". Based on data from 317 weather stations in China from 1956 to 2005, the trends of pan evaporation and air temperature were obtained and evaporation paradox was analyzed. The conclusions include: (1 From 1956 to 2005, pan evaporation paradox existed in China as a whole while pan evaporation kept decreasing and air temperature became warmer and warmer, but it does not apply to Northeast and Southeast China; (2 From 1956 to 1985, pan evaporation paradox existed narrowly as a whole with unobvious climate warming trend, but it does not apply to Northeast China; (3 From 1986 to 2005, in the past 20 years, pan evaporation paradox did not exist for the whole period while pan evaporation kept increasing, although it existed in South China. Furthermore, the trend of other weather factors including sunshine duration, windspeed, humidity and vapor pressure deficit, and their relations with pan evaporation are discussed. As a result, it can be concluded that pan evaporation decreasing is caused by the decreasing in radiation and wind speed before 1985 and pan evaporation increasing is caused by the decreasing in vapor pressure deficit due to strong warming after 1986. With the Budyko curve, it can be concluded that the actual evaporation decreased in the former 30 years and increased in the latter 20 year for the whole China.

  17. Long Duration Testing of a Spacesuit Water Membrane Evaporator Prototype

    Science.gov (United States)

    Bue, Grant C.; Makinen, Janice; Cox, Marlon; Watts, Carly; Campbell, Colin; Vogel, Matthew; Colunga, Aaron; Conger, Bruce

    2012-01-01

    The Spacesuit Water Membrane Evaporator (SWME) is a heat-rejection device that is being developed to perform thermal control for advanced spacesuits. Cooling is achieved by circulating water from the liquid cooling garment (LCG) through hollow fibers (HoFi s), which are small hydrophobic tubes. Liquid water remains within the hydrophobic tubes, but water vapor is exhausted to space, thereby removing heat. A SWME test article was tested over the course of a year, for a total of 600 cumulative hours. In order to evaluate SWME tolerance to contamination due to constituents caused by distillation processes, these constituents were allowed to accumulate in the water as evaporation occurred. A test article was tested over the course of a year for a total of 600 cumulative hours. The heat rejection performance of the SWME degraded significantly--below 700 W, attributable to the accumulation of rust in the circulating loop and biofilm growth. Bubble elimination capability, a feature that was previously proven with SWME, was compromised during the test, most likely due to loss of hydrophobic properties of the hollow fibers. The utilization of water for heat rejection was shown not to be dependent on test article, life cycle, heat rejection rate, or freezing of the membranes.

  18. Energy and exergy analysis of counter flow wet cooling towers

    Directory of Open Access Journals (Sweden)

    Saravanan Mani

    2008-01-01

    Full Text Available Cooling tower is an open system direct contact heat exchanger, where it cools water by both convection and evaporation. In this paper, a mathematical model based on heat and mass transfer principle is developed to find the outlet condition of water and air. The model is solved using iterative method. Energy and exergy analysis infers that inlet air wet bulb temperature is found to be the most important parameter than inlet water temperature and also variation in dead state properties does not affect the performance of wet cooling tower. .

  19. Evaporative oxidation treatability test report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-04-01

    In 1992, Congress passed the Federal Facilities Compliance Act that requires the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with the Resource Conservation and Recovery Act (RCRA) land disposal restrictions (LDRs). In response to the need for mixed-waste treatment capacity where available off-site commercial treatment facilities do not exist or cannot be used, the DOE Albuquerque Operations Office (DOE-AL) organized a Treatment Selection Team to match mixed wastes with treatment options and develop a strategy for treatment of its mixed wastes. DOE-AL manages operations at nine sites with mixed-waste inventories. The Treatment Selection Team determined a need to develop mobile treatment capacity to treat wastes at the sites where the wastes are generated. Treatment processes used for mixed waste not only must address the hazardous component (i.e., meet LDRs) but also must contain the radioactive component in a form that allows final disposal while protecting workers, the public, and the environment. On the basis of recommendations of the Treatment Selection Team, DOE-AL assigned projects to the sites to bring mixed-waste treatment capacity on-line. The three technologies assigned to the DOE Grand Junction Projects Office (GJPO) are evaporative oxidation, thermal desorption, and treated wastewater evaporation. Rust Geotech, the DOE-GJPO prime contractor, was assigned to design and fabricate mobile treatment units (MTUs) for these three technologies and to deliver the MTUs to selected DOE-AL sites. To conduct treatability tests at the GJPO, Rust leased a pilot-scale evaporative oxidation unit from the Clemson Technical Center (CTC), Anderson, South Carolina. The purpose of this report is to document the findings and results of tests performed using this equipment.

  20. One-dimensional Simulation of Heat Structure Melting and Evaporation Under High Heat Flux Condition Using MARS

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon-Woo; Lee, Jeong-Hun; Cho, Hyoung-Kyu; Park, Goon-Cherl [Seoul National University, Seoul (Korea, Republic of); Im, Kihak [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In order to establish the successful application for high heat flux condition, it is necessary to analyze material damage including possible phase change such as melting and evaporation due to high heat flux. In addition, in terms of coolant, water which is widely used for coolant has serious concern in that critical heat flux (CHF) occurrence can degrade the cooling capability and aggravate the integrity of cooling components. However, MARS code cannot simulate the melting and evaporation of materials under high heat flux or heat generation condition by itself due to the absence of those models. In the present study, therefore, one dimensional heat conduction calculation module for heat structure melting and evaporation was developed and coupled with MARS to overcome the limitation of material phase change simulation capability in MARS code. As clarifying the high heat flux problem, plasma facing component of Korean demonstration fusion reactor, K-DEMO, was selected. The one-dimensional simulation of melting and evaporation of high heat flux component was performed using MARS and newly developed phase change simulation module. The target component and high heat flux condition were referred to geometry of plasma facing component in Korean fusion demonstration plant and fusion reactor's plasma disruption event. In order to simulate melting and evaporation, effective heat capacity method and evaporation model were applied to phase change simulation module. The simulation results showed several phenomena such as melting, evaporation and CHF occurrence in coolant channel.

  1. Development and parametric evaluation of the prototype 2 and 3 flash evaporators

    Science.gov (United States)

    Hixon, C. W.; Dietz, J. B.

    1975-01-01

    Development of the Prototype 2 and 3 flash evaporator heat sinks which vaporize an expendable fluid to cool a heat transport fluid loop is reported. The units utilize Freon 21 as the heat transport fluid and water as the expendable fluid to meet the projected performance requirements of the space shuttle for both on-orbit and ascent/reentry operations. The evaporant is pulse-sprayed by on-off control onto heat transfer surfaces containing the transport fluid and exhausted to the vacuum environment through fixed area exhaust ducts.

  2. Simplified models for assessing heat and mass transfer in evaporative towers

    CERN Document Server

    Angelis, Alessandra De; Lorenzini, Giulio

    2013-01-01

    The aim of this book is to supply valid and reasonable parameters in order to guide the choice of the right model of industrial evaporative tower according to operating conditions which vary depending on the particular industrial context: power plants, chemical plants, food processing plants and other industrial facilities are characterized by specific assets and requirements that have to be satisfied. Evaporative cooling is increasingly employed each time a significant water flow at a temperature which does not greatly differ from ambient temperature is needed for removing a remarkable heat l

  3. Hydrodynamic Instabilities Produced by Evaporation

    Science.gov (United States)

    Romo-Cruz, Julio Cesar Ruben; Hernandez-Zapata, Sergio; Ruiz-Chavarria, Gerardo

    2012-11-01

    When a liquid layer (alcohol in the present work) is in an environment where its relative humidity is less than 100 percent evaporation appears. When RH is above a certain threshold the liquid is at rest. If RH decreases below this threshold the flow becomes unstable, and hydrodynamic cells develop. The aim of this work is to understand the formation of those cells and its main features. Firstly, we investigate how the cell size depends on the layer width. We also study how temperature depends on the vertical coordinate when the cells are present. An inverse temperature gradient is found, that is, the bottom of liquid layer is colder than the free surface. This shows that the intuitive idea that the cells are due to a direct temperature gradient, following a Marangoni-like process, does not work. We propose the hypothesis that the evaporation produce a pressure gradient that is responsible of the cell development. On the other hand, using a Schlieren technique we study the topography of the free surface when cells are present. Finally the alcohol vapor layer adjacent to the liquid surface is explored using scattering experiments, giving some insight on the plausibility of the hypothesis described previously. Authors acknowledge support by DGAPA-UNAM under project IN116312 ``Vorticidad y ondas no lineales en fluidos.''

  4. Modelling and performance of heat pipes with long evaporator sections

    Science.gov (United States)

    Wits, Wessel W.; te Riele, Gert Jan

    2017-11-01

    This paper presents a planar cooling strategy for advanced electronic applications using heat pipe technology. The principle idea is to use an array of relatively long heat pipes, whereby heat is disposed to a long section of the pipes. The proposed design uses 1 m long heat pipes and top cooling through a fan-based heat sink. Successful heat pipe operation and experimental performances are determined for seven heating configurations, considering active bottom, middle and top sections, and four orientation angles (0°, 30°, 60° and 90°). For all heating sections active, the heat pipe oriented vertically in an evaporator-down mode and a power input of 150 W, the overall thermal resistance was 0.014 K/W at a thermal gradient of 2.1 K and an average operating temperature of 50.7 °C. Vertical operation showed best results, as can be expected; horizontally the heat pipe could not be tested up to the power limit and dry-out occurred between 20 and 80 W depending on the heating configuration. Heating configurations without the bottom section active demonstrated a dynamic start-up effect, caused by heat conduction towards the liquid pool and thereafter batch-wise introducing the working fluid into the two-phase cycle. By analysing the heat pipe limitations for the intended operating conditions, a suitable heat pipe geometry was chosen. To predict the thermal performance a thermal model using a resistance network was created. The model compares well with the measurement data, especially for higher input powers. Finally, the thermal model is used for the design of a 1 kW planar system-level electronics cooling infrastructure featuring six 1 m heat pipes in parallel having a long ( 75%) evaporator section.

  5. New models for droplet heating and evaporation

    KAUST Repository

    Sazhin, Sergei S.

    2013-02-01

    A brief summary of new models for droplet heating and evaporation, developed mainly at the Sir Harry Ricardo Laboratory of the University of Brighton during 2011-2012, is presented. These are hydrodynamic models for mono-component droplet heating and evaporation, taking into account the effects of the moving boundary due to evaporation, hydrodynamic models of multi-component droplet heating and evaporation, taking and not taking into account the effects of the moving boundary, new kinetic models of mono-component droplet heating and evaporation, and a model for mono-component droplet evaporation, based on molecular dynamics simulation. The results, predicted by the new models are compared with experimental data and the prehctions of the previously developed models where possible. © 2013 Asian Network for Scientific Information.

  6. Restaurant Food Cooling Practices†

    Science.gov (United States)

    BROWN, LAURA GREEN; RIPLEY, DANNY; BLADE, HENRY; REIMANN, DAVE; EVERSTINE, KAREN; NICHOLAS, DAVE; EGAN, JESSICA; KOKTAVY, NICOLE; QUILLIAM, DANIELA N.

    2017-01-01

    Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention’s Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study. PMID:23212014

  7. Role of evaporation in gravitational collapse

    CERN Document Server

    Baccetti, Valentina; Terno, Daniel R

    2016-01-01

    We study collapse of evaporating thin dust shells using two families of metrics to describe the {exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. Both allow incorporation of Page's evaporation law (the latter in terms of the time at infinity), resulting in a modified equation} of motion for the shell. In these scenarios we find in each case that the collapse is accelerated due to evaporation, but the Schwarzschild radius is not crossed. Instead the shell is always at a certain sub-Planckian distance from this would-be horizon that depends only on the mass and evaporation rate.

  8. Adiabatic Cooling of Antiprotons

    CERN Document Server

    Gabrielse, G; McConnell, R; Richerme, P; Kalra, R; Novitski, E; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Fitzakerley, D; George, M C; Hessels, E A; Storry, C H; Weel, M; Mullers, A; Walz, J

    2011-01-01

    Adiabatic cooling is shown to be a simple and effective method to cool many charged particles in a trap to very low temperatures. Up to 3 x 10(6) (p) over bar are cooled to 3.5 K-10(3) times more cold (p) over bar and a 3 times lower (p) over bar temperature than previously reported. A second cooling method cools (p) over bar plasmas via the synchrotron radiation of embedded (p) over bar (with many fewer (p) over bar than (p) over bar) in preparation for adiabatic cooling. No (p) over bar are lost during either process-a significant advantage for rare particles.

  9. A new laser cooling method for lithium atom interferometry

    Science.gov (United States)

    Kim, Geena

    An atom interferometer offers means to measure physical constants and physical quantities with a high precision, with relatively low cost and convenience as a table-top experiment. A precision measurement of a gravitational acceleration can test fundamental physics concepts such as Einstein equivalence principle (EEP). We identified that the two lithium isotopes (7Li and 6Li) have an advantage for the test of EEP, according to the standard model extension (SME). We aim to build the world's first lithium atom interferometer and test the Einstein equivalence principle. We demonstrate a new laser cooling method suitable for a lithium atom interferometer. Although lithium is often used in ultra-cold atom experiments for its interesting physical properties and measurement feasibility, it is more difficult to laser cool lithium than other alkali atoms due to its unresolved hyperfine states, light mass (large recoil velocity) and high temperature from the oven. Typically, standard laser cooling techniques such as Zeeman slowers and magneto-optical traps are used to cool lithium atoms to about 1 mK, and the evaporative cooling method is used to cool lithium atoms to a few muK for Bose-Einstein condensate (BEC) experiments. However, for the atom interferometry purpose, the evaporative cooling method is not ideal for several reasons: First, its cooling efficiency is so low (0.01 % or less) that typically only 104-105 atoms are left after cooling when one begins with 10. 9 atoms. More atoms in anatom interferometer are needed to have a better signal to noise ratio. Second, an evaporative cooling is used to make a BEC, but we do not need a BEC to make an atom interferometer. In an atom interferometer, a high density of atoms as in a BEC should be avoided since it causes a phase shift due to atom interactions. Third, a setup for an evaporative cooling requires intricate RF generating coils or a high power laser. With a simple optical lattice and a moderate laser power (100 m

  10. Entropy Budget for Hawking Evaporation

    Directory of Open Access Journals (Sweden)

    Ana Alonso-Serrano

    2017-07-01

    Full Text Available Blackbody radiation, emitted from a furnace and described by a Planck spectrum, contains (on average an entropy of 3 . 9 ± 2 . 5 bits per photon. Since normal physical burning is a unitary process, this amount of entropy is compensated by the same amount of “hidden information” in correlations between the photons. The importance of this result lies in the posterior extension of this argument to the Hawking radiation from black holes, demonstrating that the assumption of unitarity leads to a perfectly reasonable entropy/information budget for the evaporation process. In order to carry out this calculation, we adopt a variant of the “average subsystem” approach, but consider a tripartite pure system that includes the influence of the rest of the universe, and which allows “young” black holes to still have a non-zero entropy; which we identify with the standard Bekenstein entropy.

  11. Cooling tower plume - model and experiment

    Directory of Open Access Journals (Sweden)

    Cizek Jan

    2017-01-01

    Full Text Available The paper discusses the description of the simple model of the, so-called, steam plume, which in many cases forms during the operation of the evaporative cooling systems of the power plants, or large technological units. The model is based on semi-empirical equations that describe the behaviour of a mixture of two gases in case of the free jet stream. In the conclusion of the paper, a simple experiment is presented through which the results of the designed model shall be validated in the subsequent period.

  12. Advances in rapid cooling treatment for heat stroke

    Directory of Open Access Journals (Sweden)

    Jia-jia ZHAO

    2014-10-01

    Full Text Available Heat stroke is a life-threatening disease characterized clinically by central nervous system dysfunction and severe hyperthermia (core temperature rises to higher than 40℃. The unchecked rise of body core temperature overwhelms intrinsic or extrinsic heat generation mechanism, thus overwhelms homoeostatic thermoregulation. Hyperthermia causes cellular and organ dysfunction with progressive exacerbation resulting in multi-organ failure and death. Rapid cooling to reduce core temperature as quickly as possible is the primary and most effective treatment, as it has been shown that the major determinant of outcome in heatstroke is the degree and duration of hyperthermia. If suppression of body temperature is delayed, the fatality rate will be elevated. Several cooling methods are available, including physical cooling by conduction, convection and evaporation with ice/cold water immersion, internal cooling by invasive methods such as hemofiltration, intravascular cooling, cold water gastric and rectal lavage, and cooling with drugs. It is crucial to formulate a scientific and reasonable strategy for the subsequent treatment in accordance with the patient's physical condition, the condition of cooling equipment, and the manipulator's proficiency in cooling methods and equipment usage. This article reviews the domestic and international advances in study of rapid and efficient cooling measures for heat stroke. DOI: 10.11855/j.issn.0577-7402.2014.10.17

  13. Air/fuel ratio control system having an evaporated fuel purging control arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, S.; Narasaka, S.; Otsuka, K.

    1983-03-22

    An air/fuel ratio control system for performing feedback control of the air/fuel ratio of an air/fuel mixture being supplied to an internal combustion engine. The air/fuel ratio control system is provided with an evaporated fuel purging control arrangement which is adapted to use an engine cooling water temperature sensor as an engine temperature sensor for control of purging of evaporated fuel from a canister to a venturi of the engine. At the same time, the above sensor is used for detection of various engine operating conditions for control of the air/fuel ratio of the mixture and adapted to produce an output continuously variable with a change in the temperature of engine coolant. The preclusion of the use of a special temperature sensor simplifies the structure of the evaporated fuel purging arrangement.

  14. Compensation of flow maldistribution in fin-and-tube evaporators for residential air-conditioning

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Brix, Wiebke; Elmegaard, Brian

    2011-01-01

    Compensation of flow maldistribution in multi-channel fin-and-tube evaporators for residential air-conditioning is investigated by numerical modeling. The considered sources of maldistribution are distribution of the liquid and vapor phases in the distributor and non-uniform airflow distribution....... Fin-and-tube heat exchangers usually have a predefined circuitry, however, the evaporator model is simplified to have straight tubes, in order to perform a generic investigation. The compensation of flow maldistribution is performed by control of the superheat in the individual channels. Furthermore......, the effect of combinations of individual maldistribution sources is investigated for different evaporator sizes and outdoor temperatures. It is shown that a decrease in cooling capacity and coefficient of performance by flow maldistribution can be compensated by the control of individual channel superheat...

  15. Heat transfer in condensation and evaporation. Application to industrial and environmental processes

    Energy Technology Data Exchange (ETDEWEB)

    Marvillet, C. [CEA/Grenoble, Dept. de Thermohydraulique et de Physique (DRN-GRETh), 38 (France); Vidil, R. [CEA/Saclay, Direction des Technologies Avancees (DTA), 38 - Grenoble (France)

    1999-07-01

    Eurotherm Seminar number 62 objective is to provide a European forum for the presentation and the discussion of recent researches on heat transfer in condensation and evaporation and recent developments relevant to evaporators, condensers technology for: industrial processes; air conditioning and refrigeration processes; environmental processes; food industry processes; cooling processes of electronic or mechanical devices. The following topics are to be addressed: fundamentals of phase with pure fluids and mixtures; enhanced surfaces for improved tubular or plate heat exchangers; advanced methods and software for condenser and evaporator simulation and design; innovative design and concept of heat exchangers. This 2-days Seminar will be interest to a large group of researches and engineers from universities, research centres and industry. (authors)

  16. Mass transfer relations for transpiration evaporation experiments

    NARCIS (Netherlands)

    Limpt, J.A.C. van; Beerkens, R.G.C.; Lankhorst, A.M.; Habraken, A.

    2005-01-01

    Transpiration evaporation experiments are often used to study evaporation kinetics from liquids or melts. The mass transport of volatile species in a transpiration experiment depends among others on the flow conditions of the carrier gas in the tube and on the geometrical configuration. For a

  17. Odors from evaporation of acidified pig urine

    NARCIS (Netherlands)

    Willers, H.C.; Hobbs, P.J.; Ogink, N.W.M.

    2004-01-01

    In the Dutch Hercules project feces and urine from pigs are collected separately underneath the slatted floor in a pig house and treated in two processes. Feces are composted and urine is concentrated by water evaporation in a packed bed. Exhaust air from the pig house is used for the evaporation in

  18. Spheroid droplets evaporation of water solutions

    OpenAIRE

    Misyura S. Y.; Morozov V.S.

    2017-01-01

    Droplet film boiling on a horizontal heating surface was studied experimentally. The heat transfer coefficient of droplet water solution in the spheroidal state decreases with a rise of wall overheating and spheroid diameter. Evaporation of small spheroid (diameter d 20 mm). At the evaporation of large spheroids a spheroid shape changes in time that significantly affect coefficients of generalizing curves that use dimensionless numbers.

  19. Evaporation experiments and modelling for glass melts

    NARCIS (Netherlands)

    Limpt, J.A.C. van; Beerkens, R.G.C.

    2007-01-01

    A laboratory test facility has been developed to measure evaporation rates of different volatile components from commercial and model glass compositions. In the set-up the furnace atmosphere, temperature level, gas velocity and batch composition are controlled. Evaporation rates have been measured

  20. Evaporation from partially covered water surfaces

    Science.gov (United States)

    Assouline, S.; Narkis, K.; Or, D.

    2010-10-01

    Evaporative losses from large water bodies may exceed 20% of water used in irrigated agriculture, with losses from reservoirs estimated at 50% of storage capacity. Prominent among proposed methods to curtail these evaporative losses are various forms of partial covers placed over water surfaces. Studies show that evaporation through perforated covers and from partially covered water surfaces exhibit nonlinear behavior, where rates of water loss are not proportional to uncovered surface fraction and are significantly affected by opening size and relative spacing. We studied evaporation from small water bodies under various perforated covers, extending the so-called diameter law to opening sizes in the range of 10-5 to 10-1 m. Contradicting claims concerning effects of openings and their arrangement on performance of evaporation barriers are analyzed on per opening and on per area mass losses. Our results help reconcile some classical findings invoking detailed pore-scale diffusion and simple temperature-based energetic behaviors. For fixed relative spacing, area-averaged evaporative flux density remains nearly constant across several orders of magnitude variations in opening size. For the scale of the experimental setup, we predict relative evaporation reduction efficiency for various configurations of perforated evaporation barriers.

  1. An evaporation based digital microflow meter

    NARCIS (Netherlands)

    Nie, C; Frijns, A J H; Mandamparambil, R; Zevenbergen, M A G; den Toonder, J M J

    2015-01-01

    In this work, we present a digital microflow meter operating in the range 30-250 nl min-1 for water. The principle is based on determining the evaporation rate of the liquid via reading the number of wetted pore array structures in a microfluidic system, through which continuous evaporation takes

  2. Advanced evaporator technology progress report FY 1992

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlain, D.; Hutter, J.C.; Leonard, R.A. [and others

    1995-01-01

    This report summarizes the work that was completed in FY 1992 on the program {open_quotes}Technology Development for Concentrating Process Streams.{close_quotes} The purpose of this program is to evaluate and develop evaporator technology for concentrating radioactive waste and product streams such as those generated by the TRUEX process. Concentrating these streams and minimizing the volume of waste generated can significantly reduce disposal costs; however, equipment to concentrate the streams and recycle the decontaminated condensates must be installed. LICON, Inc., is developing an evaporator that shows a great deal of potential for this application. In this report, concepts that need to be incorporated into the design of an evaporator operated in a radioactive environment are discussed. These concepts include criticality safety, remote operation and maintenance, and materials of construction. Both solubility and vapor-liquid equilibrium data are needed to design an effective process for concentrating process streams. Therefore, literature surveys were completed and are summarized in this report. A model that is being developed to predict vapor phase compositions is described. A laboratory-scale evaporator was purchased and installed to study the evaporation process and to collect additional data. This unit is described in detail. Two new LICON evaporators are being designed for installation at Argonne-East in FY 1993 to process low-level radioactive waste generated throughout the laboratory. They will also provide operating data from a full-sized evaporator processing radioactive solutions. Details on these evaporators are included in this report.

  3. Influence of Hot-Carrier Extraction from a Photovoltaic Absorber: An Evaporative Approach

    Science.gov (United States)

    Suchet, Daniel; Jehl, Zacharie; Okada, Yoshitaka; Guillemoles, Jean-Francois

    2017-09-01

    The effect of energy-selective extraction on a hot carrier's population is addressed in this study. Using an evaporative cooling model inspired by the field of cold atoms, we derive an analytical expression supported by numerical calculations to account for the removal of particles from the distribution and subsequent energy redistribution among the remaining carriers. Depending on the filtering dimensionality and energy level of extraction, the distribution can be either heated up or cooled down, resulting in a modification of the current-voltage characteristic associated to the structure. The negative differential resistance peak indicating the selective extraction is shown to be markedly reduced when evaporation is considered, which may lead to an overestimation of the tunneling current in previous models. These results provide insights into the interpretation of experimental results on energy-selective contacts, as well as a straightforward method to unequivocally demonstrate the energy filtering of hot carriers in a structure operating under continuous illumination.

  4. Multi-leg heat pipe evaporator

    Science.gov (United States)

    Alario, J. P.; Haslett, R. A.

    1986-04-01

    A multileg heat pipe evaporator facilitates the use and application of a monogroove heat pipe by providing an evaporation section which is compact in area and structurally more compatible with certain heat exchangers or heat input apparatus. The evaporation section of a monogroove heat pipe is formed by a series of parallel legs having a liquid and a vapor channel and a communicating capillary slot therebetween. The liquid and vapor channels and interconnecting capillary slots of the evaporating section are connected to the condensing section of the heat pipe by a manifold connecting liquid and vapor channels of the parallel evaporation section legs with the corresponding liquid and vapor channels of the condensing section.

  5. Contribution of impervious surfaces to urban evaporation

    Science.gov (United States)

    Ramamurthy, P.; Bou-Zeid, E.

    2014-04-01

    Observational data and the Princeton urban canopy model, with its detailed representation of urban heterogeneity and hydrological processes, are combined to study evaporation and turbulent water vapor transport over urban areas. The analyses focus on periods before and after precipitation events, at two sites in the Northeastern United States. Our results indicate that while evaporation from concrete pavements, building rooftops, and asphalt surfaces is discontinuous and intermittent, overall these surfaces accounted for nearly 18% of total latent heat fluxes (LE) during a relatively wet 10 day period. More importantly, these evaporative fluxes have a significant impact on the urban surface energy balance, particularly during the 48 h following a rain event when impervious evaporation is the highest. Thus, their accurate representation in urban models is critical. Impervious evaporation after rainfall is also shown to correlate the sources of heat and water at the earth surface, resulting in a conditional scalar transport similarity over urban terrain following rain events.

  6. Performance of falling film plate evaporators in reconstructed multiple-effect evaporation station in sugar factory

    Directory of Open Access Journals (Sweden)

    Zavargo Zoltan Z.

    2006-01-01

    Full Text Available General trend of free trade in regional level as well as in the direction of European Union has motivated sugar factories located in Serbia to invest into technologies that are more efficient in order to make their products more competitive at the markets in Europe. The aim of this work was to evaluate effects of falling film plate evaporators on the energy consumption of evaporation plant, as well as to validate performance of this type of evaporators. It was found that this type of evaporator decreased energy requirements and in the same time evaporation process was more effective due to high values of heat transfer coefficients. .

  7. Liquid desiccant dehumidification and regeneration process to meet cooling and freshwater needs of desert greenhouses

    KAUST Repository

    Lefers, Ryan

    2016-04-19

    Agriculture accounts for ~70% of freshwater usage worldwide. Seawater desalination alone cannot meet the growing needs for irrigation and food production, particularly in hot, desert environments. Greenhouse cultivation of high-value crops uses just a fraction of freshwater per unit of food produced when compared with open field cultivation. However, desert greenhouse producers face three main challenges: freshwater supply, plant nutrient supply, and cooling of the greenhouse. The common practice of evaporative cooling for greenhouses consumes large amounts of fresh water. In Saudi Arabia, the most common greenhouse cooling schemes are fresh water-based evaporative cooling, often using fossil groundwater or energy-intensive desalinated water, and traditional refrigeration-based direct expansion cooling, largely powered by the burning of fossil fuels. The coastal deserts have ambient conditions that are seasonally too humid to support adequate evaporative cooling, necessitating additional energy consumption in the dehumidification process of refrigeration-based cooling. This project evaluates the use of a combined-system liquid desiccant dehumidifier and membrane distillation unit that can meet the dual needs of cooling and freshwater supply for a greenhouse in a hot and humid environment. © 2016 Balaban Desalination Publications. All rights reserved.

  8. Cooling water distribution system

    Science.gov (United States)

    Orr, Richard

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

  9. Heat Power Determination of Dv-290 Refrigerator's Evaporator on the Basis of Thermodynamic Parameters of Inlet Air / Określenie Mocy Cieplnej Parownika Chłodziarki Dv-290 Na Podstawie Parametrów Termodynamicznych Powietrza Wlotowego

    Science.gov (United States)

    Nowak, Bernard; Kuczera, Zbigniew

    2012-12-01

    The present paper introduces a method for calculating the thermal power of DV-290 mining air cooler's evaporator. The power usually differs from the nominal power given by the manufacturer. The thermodynamic parameters of cooled air are not obtained as a result of in situ measurements, but in indirect manner that is by determining the evaporation and condensation's pressure values of R407C refrigerant. The pressure dependencies formulated as a function of air enthalpy at the evaporator's inlet were obtained using calculations of a computer program which solves the system of equations describing heat and mass transfer in the refrigerator's compressor on the basis of previous measurements of air performed before and after its cooling. The obtained dependencies are demonstrated in a graphical (fig. 2 and fig. 3) and analytical (the regression equations (19) and (20)) manner, the values of correlation coefficients are also presented. For the known evaporation and condensation pressure values of the refrigerant, and thus for its basic physical parameters the complete thermal power of the evaporator was determined, that is its: air cooling overt power, dehumidification occult power, temperature, relative humidity and specific humidity of air after its cooling. In addition, using the mentioned method, the capacity of DV-290 refrigerator's evaporator is provided for the given thermodynamic parameters of air before cooling, along with air thermodynamic parameters after cooling.

  10. High-Capacity Spacesuit Evaporator Absorber Radiator (SEAR)

    Science.gov (United States)

    Izenson, Michael G.; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Quinn, Gregory

    2015-01-01

    Future human space exploration missions will require advanced life support technology that can operate across a wide range of applications and environments. Thermal control systems for space suits and spacecraft will need to meet critical requirements for water conservation and multifunctional operation. This paper describes a Space Evaporator Absorber Radiator (SEAR) that has been designed to meet performance requirements for future life support systems. A SEAR system comprises a lithium chloride absorber radiator (LCAR) for heat rejection coupled with a space water membrane evaporator (SWME) for heat acquisition. SEAR systems provide heat pumping to minimize radiator size, thermal storage to accommodate variable environmental conditions, and water absorption to minimize use of expendables. We have built and tested a flight-like, high-capacity LCAR, demonstrated its performance in thermal vacuum tests, and explored the feasibility of an ISS demonstration test of a SEAR system. The new LCAR design provides the same cooling capability as prior LCAR prototypes while enabling over 30% more heat absorbing capacity. Studies show that it should be feasible to demonstrate SEAR operation in flight by coupling with an existing EMU on the space station.

  11. 242-A evaporator safety analysis report

    Energy Technology Data Exchange (ETDEWEB)

    CAMPBELL, T.A.

    1999-05-17

    This report provides a revised safety analysis for the upgraded 242-A Evaporator (the Evaporator). This safety analysis report (SAR) supports the operation of the Evaporator following life extension upgrades and other facility and operations upgrades (e.g., Project B-534) that were undertaken to enhance the capabilities of the Evaporator. The Evaporator has been classified as a moderate-hazard facility (Johnson 1990). The information contained in this SAR is based on information provided by 242-A Evaporator Operations, Westinghouse Hanford Company, site maintenance and operations contractor from June 1987 to October 1996, and the existing operating contractor, Waste Management Hanford (WMH) policies. Where appropriate, a discussion address the US Department of Energy (DOE) Orders applicable to a topic is provided. Operation of the facility will be compared to the operating contractor procedures using appropriate audits and appraisals. The following subsections provide introductory and background information, including a general description of the Evaporator facility and process, a description of the scope of this SAR revision,a nd a description of the basic changes made to the original SAR.

  12. Direct Evaporatrive Coolers of Gases and Liquids with Lowered Limit of Cooling

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2015-12-01

    Full Text Available We have developed main technical solutions solution of indirect evaporative water and air coolers with reduced cooling limit. Packed part of heat-mass transfer devices is made of the film type based monoblock compositions of polymer materials. A mathematical model describing the processes of joint heat and mass transfer in evaporative coolers is executed. A comparative analysis of the possibilities of coolers designed based on experimental data on the efficiency of processes of heat and mass transfer.

  13. Film evaporation MEMS thruster array for micropropulsion

    Science.gov (United States)

    Cofer, Anthony G.

    Current small sat propulsion systems require a substantial mass fraction of the vehicle involving tradeoffs between useful payload mass and maneuverability. This is also an issue with available attitude control systems which are either quickly saturated reaction wheels or movable high drag surfaces with long response times. What is needed is a low mass low power self-contained propulsion unit that can be easily installed and modeled. The proposed Film-Evaporation MEMS Tunable Array (FEMTA), exploits the small scale surface tension effect in conjunction with temperature dependent vapor pressure to realize a thermal valving system. The local vapor pressure is increased by resistive film heating until it exceeds meniscus strength in the nozzle inducing vacuum boiling which provides a stagnation pressure equal to vapor pressure at that point which is used for propulsion. The heat of vaporization is drawn from the bulk fluid and is replaced by either an integrated heater or waste heat from the vehicle. Proof of concept was initially achieved with a macroscale device made possible by using ethylene glycol, which has a low vapor pressure and high surface tension, as the working fluid. Both the thermal valving effect and cooling feature were demonstrated though at reduced performance than would be expected for water. Three generations of prototype FEMTA devices have been fabricated at Birck Nanotechnology Center on 200 and 500 micrometer thick silicon wafers. Preliminary testing on first generation models had tenuously demonstrated behavior consistent with the macroscale tests but there was not enough data for solid confirmation. Some reliability issues had arisen with the integrated heaters which were only partially alleviated in the second generation of FEMTAs. This led to a third generation and two changes in heater material until a chemically resilient material was found. The third generation of microthrusters were tested on the microNewton thrust stand at Purdue

  14. Heat transfer, diffusion, and evaporation

    Science.gov (United States)

    Nusselt, Wilhelm

    1954-01-01

    Although it has long been known that the differential equations of the heat-transfer and diffusion processes are identical, application to technical problems has only recently been made. In 1916 it was shown that the speed of oxidation of the carbon in iron ore depends upon the speed with which the oxygen of the combustion air diffuses through the core of gas surrounding the carbon surface. The identity previously referred to was then used to calculate the amount of oxygen diffusing to the carbon surface on the basis of the heat transfer between the gas stream and the carbon surface. Then in 1921, H. Thoma reversed that procedure; he used diffusion experiments to determine heat-transfer coefficients. Recently Lohrisch has extended this work by experiment. A technically very important application of the identity of heat transfer and diffusion is that of the cooling tower, since in this case both processes occur simultaneously.

  15. Suncatcher and cool pool. Project report

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, J.

    1981-03-01

    The Suncatcher is a simple, conical solar concentrating device that captures light entering clerestory windows and directs it onto thermal storage elements at the back of a south facing living space. The cone shape and inclination are designed to capture low angle winter sunlight and to reflect away higher angle summer sunlight. It is found that winter radiation through a Suncatcher window is 40 to 50% higher than through an ordinary window, and that the average solar fraction is 59%. Water-filled steal culvert pipes used for thermal storage are found to undergo less stratification, and thus to be more effective, when located where sunlight strikes the bottom rather than the top. Five Suncatcher buildings are described. Designs are considered for 32/sup 0/, 40/sup 0/ and 48/sup 0/ north latitude, and as the latitude increases, the inclination angle of the cone should be lowered. The Cool Pool is an evaporating, shaded roof pond which thermosiphons cool water into water-filled columns within a building. Preliminary experiments indicate that the best shade design has unimpeded north sky view, good ventilation, complete summer shading, a low architectural profile, and low cost attic vent lowers work. Another series of experiments established the satisfactory performance of the Cool Pool on a test building using four water-filled cylinders, two cylinders, and two cylinders connected to the Cool Pool through a heat exchanger. Although an unshaded pool cools better at night than a shaded one, daytime heat gain far offsets this advantage. A vinyl waterbag heat exchanger was developed for use with the Cool Pool. (LEW)

  16. Spacesuit Water Membrane Evaporator Integration with the ISS Extravehicular Mobility Unit

    Science.gov (United States)

    Margiott, Victoria; Boyle, Robert

    2014-01-01

    NASA has developed a Solid Water Membrane Evaporation (SWME) to provide cooling for the next generation spacesuit. The current spacesuit team has looked at this technology from the standpoint of using the ISS EMU to demonstrate the SWME technology while EVA, and from the standpoint of augmenting EMU cooling in the case of a fouled EMU cooling system. One approach to increasing the TRL of the system is to incorporate this hardware with the existing EMU. Several integration issues were addressed to support a potential demonstration of the SWME with the existing EMU. Systems analysis was performed to assess the capability of the SWME to maintain crewmember cooling and comfort as a replacement for sublimation. The materials of the SWME were reviewed to address compatibility with the EMU. Conceptual system placement and integration with the EMU via an EVA umbilical system to ensure crew mobility and Airlock egress were performed. A concept of operation for EVA use was identified that is compatible with the existing system. This concept is extensible as a means to provide cooling for the existing EMU. The cooling system of one of the EMUs on orbit has degraded, with the root cause undetermined. Should there be a common cause resident on ISS, this integration could provide a means to recover cooling capability for EMUs on orbit.

  17. Temperature responsive cooling apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Weker, M.L.; Stearns, R.M.

    1987-08-11

    A temperature responsive cooling apparatus is described for an air conditioner or refrigeration system in operative association with a reservoir of fluid, the air conditioner or refrigeration system having an air cooled coil and means for producing a current of air for cooling the coil, the temperature responsive cooling apparatus comprising: (a) means for transferring the fluid from the reservoir to the air conditioner temperature responsive cooling apparatus, (b) a fluid control device activated by the current of air for cooling the coil; (c) a temperature activated, nonelectrical device for terminating and initiating the flow of fluid therethrough in an intermittent fashion for enhancing the operability of the compressor associated with the refrigeration system and for reducing the quantity of fluid required to cool the coil of the refrigeration system, (d) a fluid treatment device for preventing, reducing or mitigating the deposition of nonevaporative components on the air cooled coil, and (e) means for dispersing the fluid to the air cooled coil from the fluid control device for cooling the coil and increasing the efficiency of the air conditioner thereby reducing the cost of operating and maintaining the air conditioner without damaging the air conditioner and without the deposition of nonevaporative components thereupon.

  18. Towards a rational definition of potential evaporation

    Directory of Open Access Journals (Sweden)

    J.-P. Lhommel

    1997-01-01

    Full Text Available The concept of potential evaporation is defined on the basis of the following criteria: (i it must establish an upper limit to the evaporation process in a given environment (the term 'environment' including meteorological and surface conditions, and (ii this upper limit must be readily calculated from measured input data. It is shown that this upper limit is perfectly defined and is given by the Penman equation, applied with the corresponding meteorological data (incoming radiation and air characteristics measured at a reference height and the appropriate surface characteristics (albedo, roughness length, soil heat flux. Since each surface has its own potential evaporation, a function of its own surface characteristics, it is useful to define a reference potential evaporation as a short green grass completely shading the ground. Although the potential evaporation from a given surface is readily calculated from the Penman equation, its physical significance or interpretation is not so straightforward, because it represents only an idealized situation, not a real one. Potential evaporation is the evaporation from this surface, when saturated and extensive enough to obviate any effect of local advection, under the same meteorological conditions. Due to the feedback effects of evaporation on air characteristics, it does not represent the 'real' evaporation (i.e. the evaporation which could be physically observed in the real world from such an extensive saturated surface in these given meteorological conditions (if this saturated surface were substituted for an unsaturated one previously existing. From a rigorous standpoint, this calculated potential evaporation is not physically observable. Nevertheless, an approximate representation can be given by the evaporation from a limited saturated area, the dimension of which depends on the height of measurement of the air characteristics used as input in the Penman equation. If they are taken at a height

  19. Upgrading existing evaporators to reduce energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    This manual is intended to assist the evaporator engineer who will be performing the technical and economic analyses to determine the most suitable evaporator upgrading technique for his particular plant. Information is included on potentials for upgrading evaporators; correctable operating factors; heat recovery and other improvements in energy use with minor capital investments; upgrading through major capital investments; guidelines for formulating an upgrading program; and new technologies encompassing advanced designs, use of solar and low-grade heat sources, and heat transfer enhancement. A 36 item bibliography is included. (LCL)

  20. Enhanced Evaporation and Condensation in Tubes

    Science.gov (United States)

    Honda, Hiroshi

    A state-of-the-art review of enhanced evaporation and condensation in horizontal microfin tubes and micro-channels that are used for air-conditioning and refrigeration applications is presented. The review covers the effects of flow pattern and geometrical parameters of the tubes on the heat transfer performance. Attention is paid to the effect of surface tension which leads to enhanced evaporation and condensation in the microfin tubes and micro-channels. A review of prior efforts to develop empirical correlations of the heat transfer coefficient and theoretical models for evaporation and condensation in the horizontal microfin tubes and micro-channels is also presented.

  1. Gas turbine cooling system

    Science.gov (United States)

    Bancalari, Eduardo E.

    2001-01-01

    A gas turbine engine (10) having a closed-loop cooling circuit (39) for transferring heat from the hot turbine section (16) to the compressed air (24) produced by the compressor section (12). The closed-loop cooling system (39) includes a heat exchanger (40) disposed in the flow path of the compressed air (24) between the outlet of the compressor section (12) and the inlet of the combustor (14). A cooling fluid (50) may be driven by a pump (52) located outside of the engine casing (53) or a pump (54) mounted on the rotor shaft (17). The cooling circuit (39) may include an orifice (60) for causing the cooling fluid (50) to change from a liquid state to a gaseous state, thereby increasing the heat transfer capacity of the cooling circuit (39).

  2. Radiant Floor Cooling Systems

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2008-01-01

    In many countries, hydronic radiant floor systems are widely used for heating all types of buildings such as residential, churches, gymnasiums, hospitals, hangars, storage buildings, industrial buildings, and smaller offices. However, few systems are used for cooling.This article describes a floor...... cooling system that includes such considerations as thermal comfort of the occupants, which design parameters will influence the cooling capacity and how the system should be controlled. Examples of applications are presented....

  3. Denton E-beam Evaporator #1

    Data.gov (United States)

    Federal Laboratory Consortium — Description:CORAL Name: E-Beam Evap 1This is a dual e-beam/thermal evaporator for the deposition of metal and dielectric thin films. Materials available are: Ag, Al,...

  4. Denton E-beam Evaporator #2

    Data.gov (United States)

    Federal Laboratory Consortium — Description:CORAL Name: E-Beam Evap 2This is an electron gun evaporator for the deposition of metals and dielectrics thin films. Materials available are: Ag, Al, Au,...

  5. Evaporation analysis for Tank SX-104

    Energy Technology Data Exchange (ETDEWEB)

    Barrington, C.A.

    1994-10-01

    Decreases in historical interstitial liquid level measurements in tank SX-104 were compared to predictions of a numerical model based upon diffusion of water through a porous crust. The analysis showed that observed level decreases could be explained by evaporation.

  6. Lattice-Boltzmann simulations of droplet evaporation

    KAUST Repository

    Ledesma-Aguilar, Rodrigo

    2014-09-04

    © the Partner Organisations 2014. We study the utility and validity of lattice-Boltzmann (LB) simulations to explore droplet evaporation driven by a concentration gradient. Using a binary-fluid lattice-Boltzmann algorithm based on Cahn-Hilliard dynamics, we study the evaporation of planar films and 3D sessile droplets from smooth solid surfaces. Our results show that LB simulations accurately reproduce the classical regime of quasi-static dynamics. Beyond this limit, we show that the algorithm can be used to explore regimes where the evaporative and diffusive timescales are not widely separated, and to include the effect of boundaries of prescribed driving concentration. We illustrate the method by considering the evaporation of a droplet from a solid surface that is chemically patterned with hydrophilic and hydrophobic stripes. This journal is

  7. Spacesuit Evaporator-Absorber-Radiator (SEAR) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project builds from the work of the first year of effort that successfully integrated the Spacesuit  Water Membrane Evaporator (SWME), developed by the...

  8. Sensitivity and Design of a Transcritical CO2 Cooling and Heating System

    DEFF Research Database (Denmark)

    Nguyen, Chan; Veje, Christian; Willatzen, Morten

    2012-01-01

    This paper presents a theoretical design study of a transcritical CO2 heat pump system for simultaneous cooling and heating. The heat pump model consists of the components: compressor, internal heat exchanger, valve, evaporator and gas cooler. The evaporator and the gas cooler are both water...... coupled intended for district cooling and heating respectively. Initially a thermodynamic cycle analysis has been done on the system followed by a heat transfer analysis of the heat exchangers using finite difference models. The main subject of this paper is an investigation of the effects that parameter...

  9. Climatic Controls on Evaporation in Hawaii.

    Science.gov (United States)

    Nullet, Dennis Mcclain

    The primary aims of this dissertation were to identify and explain variation in potential evaporation at different elevations and different exposures on tropical high islands, to provide reference data for modeling evaporation, and to suggest how an evaporation model appropriate for tropical high islands might be developed. The most important contribution of this study was to quantify the importance of advection in controlling the evaporation rate on tropical high islands. Sensible heat advection from the surrounding ocean moderates the evaporation rate at windward coastal sites. This effect ranged, on average, from 0.85 mm/day enhancement in November to 0.71 mm/day suppression in June. Heat advection from land sources increased the evaporation rate by as much as 2.8 mm/day in central Maui. Large-scale subsidence over the Hawaiian Islands region accounts for an additional source of advection, enhancing evaporation above approximately above 1200 m on the mountain. Preliminary results indicate that this effect increases with elevation in conjunction with the night evaporation rate. Cloud patterns over the mountain slopes and optical air mass determine the solar radiation receipt (the primary source of energy for evaporation) pattern which ranged from 85% to 51% of clear-day radiation in summer and 80% to 63% in winter. Insolation declined with elevation over the study site, except above 1200 meters in winter where it increased with elevation. Results of the study indicate that common methods for estimating potential evaporation need to be modified to account for the effect of advection. Temperature and vapor pressure on the mountain can be estimated using rawinsonde data. Net radiation can be mapped from global radiation estimated from modeled clear-day radiation reduced according to a cloudiness index. Ocean advection can he accounted for at the lower elevations by simply adding a monthly modifier based on results presented in the study. Land advection can be

  10. Initial Cooling Experiment (ICE)

    CERN Multimedia

    Photographic Service; CERN PhotoLab

    1978-01-01

    In 1977, in a record-time of 9 months, the magnets of the g-2 experiment were modified and used to build a proton/antiproton storage ring: the "Initial Cooling Experiment" (ICE). It served for the verification of the cooling methods to be used for the "Antiproton Project". Stochastic cooling was proven the same year, electron cooling followed later. Also, with ICE the experimental lower limit for the antiproton lifetime was raised by 9 orders of magnitude: from 2 microseconds to 32 hours. For its previous life as g-2 storage ring, see 7405430. More on ICE: 7711282, 7809081, 7908242.

  11. Turbine airfoil cooling system with cooling systems using high and low pressure cooling fluids

    Science.gov (United States)

    Marsh, Jan H.; Messmann, Stephen John; Scribner, Carmen Andrew

    2017-10-25

    A turbine airfoil cooling system including a low pressure cooling system and a high pressure cooling system for a turbine airfoil of a gas turbine engine is disclosed. In at least one embodiment, the low pressure cooling system may be an ambient air cooling system, and the high pressure cooling system may be a compressor bleed air cooling system. In at least one embodiment, the compressor bleed air cooling system in communication with a high pressure subsystem that may be a snubber cooling system positioned within a snubber. A delivery system including a movable air supply tube may be used to separate the low and high pressure cooling subsystems. The delivery system may enable high pressure cooling air to be passed to the snubber cooling system separate from low pressure cooling fluid supplied by the low pressure cooling system to other portions of the turbine airfoil cooling system.

  12. Evaluating Evaporation with Satellite Thermal Data.

    Science.gov (United States)

    1987-11-01

    and Executive S~ury: se attachd Water surface tmiera e can be obtaind fron satellite Ueml remote senir. landsat and other satellite s emitted thermal...values with the lake’s surface temp ~eratuire by performing a linear regression to get an equation, or model, that defines the evaporation for a given...infrared radiation on a regular basis over uxfd of the earth’s surface . Evaporation is acccmplished by the net txansport of mas from the water surface

  13. High-Capacity Heat-Pipe Evaporator

    Science.gov (United States)

    Oren, J. A.; Duschatko, R. J.; Voss, F. E.; Sauer, L. W.

    1989-01-01

    Heat pipe with cylindrical heat-input surface has higher contact thermal conductance than one with usual flat surface. Cylindrical heat absorber promotes nearly uniform flow of heat into pipe at all places around periphery of pipe, helps eliminate hotspots on heat source. Lugs in aluminum pipe carry heat from outer surface to liquid oozing from capillaries of wick. Liquid absorbs heat, evaporates, and passes out of evaporator through interlug passages.

  14. Description and cost analysis of a deluge dry/wet cooling system.

    Energy Technology Data Exchange (ETDEWEB)

    Wiles, L.E.; Bamberger, J.A.; Braun, D.J.; Braun, D.J.; Faletti, D.W.; Willingham, C.E.

    1978-06-01

    The use of combined dry/wet cooling systems for large base-load power plants offers the potential for significant water savings as compared to evaporatively cooled power plants and significant cost savings in comparison to dry cooled power plants. The results of a detailed engineering and cost study of one type of dry/wet cooling system are described. In the ''deluge'' dry/wet cooling method, a finned-tube heat exchanger is designed to operate in the dry mode up to a given ambient temperature. To avoid the degradation of performance for higher ambient temperatures, water (the delugeate) is distributed over a portion of the heat exchanger surface to enhance the cooling process by evaporation. The deluge system used in this study is termed the HOETERV system. The HOETERV deluge system uses a horizontal-tube, vertical-plate-finned heat exchanger. The delugeate is distributed at the top of the heat exchanger and is allowed to fall by gravity in a thin film on the face of the plate fin. Ammonia is used as the indirect heat transfer medium between the turbine exhaust steam and the ambient air. Steam is condensed by boiling ammonia in a condenser/reboiler. The ammonia is condensed in the heat exchanger by inducing airflow over the plate fins. Various design parameters of the cooling system have been studied to evaluate their impact on the optimum cooling system design and the power-plant/utility-system interface. Annual water availability was the most significant design parameter. Others included site meteorology, heat exchanger configuration and air flow, number and size of towers, fan system design, and turbine operation. It was concluded from this study that the HOETERV deluge system of dry/wet cooling, using ammonia as an intermediate heat transfer medium, offers the potential for significant cost savings compared with all-dry cooling, while achieving substantially reduced water consumption as compared to an evaporatively cooled power plant. (LCL)

  15. Evaporation Heat Transfer of Ammonia and Pressure Drop of Warm Water for Plate Type Evaporator

    Science.gov (United States)

    Kushibe, Mitsuteru; Lkegami, Yasuyuki; Monde, Masanori; Uehara, Haruo

    The performance test of three types of plate type evaporators for spring thermal energy conversion and ocean thermal energy conversion carried out. Ammonia is utilized as working fluid and warm water is utilized as heat source. An empirical correlation is proposed in order to predict the mean evaporation heat transfer coefficient of ammonia and heat transfer coefficient of warm water for plate type evaporators. The mean heat transfer coefficient and friction factor of warm water were compared with other researches.

  16. Cool pool development. Quarterly technical report No. 1, April-June 1979

    Energy Technology Data Exchange (ETDEWEB)

    Crowther, K.

    1979-10-15

    The Cool Pool is a passive cooling system consisting of a shaded, evaporating roof pond which thermosiphons cool water into water-filled, metal columns (culvert pipes) located within the building living space. The water in the roof pond is cooled by evaporation, convection and radiation. Because the water in the pool and downcomer is colder and denser than the water in the column a pressure difference is created and the cold water flows from the pool, through the downcomer and into the bottom of the column. The warm column water rises and flows through a connecting pipe into the pool. It is then cooled and the cycle repeats itself. The system requires no pumps. The water column absorbs heat from the building interior primarily by convection and radiation. Since the column is radiating at a significantly lower temperature than the interior walls it plays a double role in human comfort. Not only does it cool the air by convection but it provides a heat sink to which people can radiate. Since thermal radiation is important to the cooling of people, the cold water column contributes substantially to their feelings of comfort. Research on the Cool Pool system includes the following major tasks: control of biological organisms and debris in the roof pond and water cylinders; development of a heat exchanger; experimental investigation of the system's thermal performance; and development of a predictive computer simulation of the Cool Pool. Progress in these tasks is reported.

  17. Investigation on performance of three personal cooling systems in mitigating heat strain by means of thermal manikin

    Directory of Open Access Journals (Sweden)

    Ren Chong-Guang

    2017-01-01

    Full Text Available The objective of current study was to examine the effectiveness of three cooling strategies (i. e., electric air fan, evaporative cooling vest, and liquid cooling vest in mitigating body heat strain in heat wave conditions by means of a Newton-type thermal manikin. A human thermoregulatory model was used to simulate human physiological responses while using the three cooling strategies. Two environmental conditions were selected to simulate heatwave conditions, i. e., 36 °C, 33% relative humidity (hot-dry, 40 °C, 27% relative humidity (extremely hotdry. A metabolic rate of 1.2 MET was selected to simulate resting person or person doing light housework. It was found that the electric air fan had cooling benefit in both environments. In addition, the evaporative cooling vest and liquid cooling vest showed similar effectiveness in mitigating body heat strain in both hot-dry or extremely hot-dry environments. Thus the evaporative cooling vest and liquid cooling vest were recommended under heatwave conditions..

  18. Solar absorption cooling

    NARCIS (Netherlands)

    Kim, D.S.

    2007-01-01

    As the world concerns more and more on global climate changes and depleting energy resources, solar cooling technology receives increasing interests from the public as an environment-friendly and sustainable alternative. However, making a competitive solar cooling machine for the market still

  19. Cooling of electronic equipment

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    2003-01-01

    Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...

  20. Measure Guideline: Ventilation Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Springer, D.; Dakin, B.; German, A.

    2012-04-01

    The purpose of this measure guideline on ventilation cooling is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  1. The final cool down

    CERN Multimedia

    Thursday 29th May, the cool-down of the final sector (sector 4-5) of LHC has begun, one week after the start of the cool-down of sector 1-2. It will take five weeks for the sectors to be cooled from room temperature to 5 K and a further two weeks to complete the cool down to 1.9 K and the commissioning of cryogenic instrumentation, as well as to fine tune the cryogenic plants and the cooling loops of cryostats.Nearly a year and half has passed since sector 7-8 was cooled for the first time in January 2007. For Laurent Tavian, AT/CRG Group Leader, reaching the final phase of the cool down is an important milestone, confirming the basic design of the cryogenic system and the ability to operate complete sectors. “All the sectors have to operate at the same time otherwise we cannot inject the beam into the machine. The stability and reliability of the cryogenic system and its utilities are now very important. That will be the new challenge for the coming months,” he explains. The status of the cool down of ...

  2. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    CERN PhotoLab

    1979-01-01

    ICE was built in 1977, using the modified bending magnets of the g-2 muon storage ring (see 7405430). Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project. Stochastic cooling proved a resounding success early in 1978 and the antiproton project could go ahead, now entirely based on stochastic cooling. Electron cooling was experimented with in 1979. The 26 kV equipment is housed in the cage to the left of the picture, adjacent to the "e-cooler" located in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7809081.

  3. Initial Cooling Experiment (ICE)

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    ICE was built in 1977, in a record time of 9 months, using the modified bending magnets of the g-2 muon storage ring. Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project, to be launched in 1978. Already early in 1978, stochastic cooling proved a resounding success, such that the antiproton (p-pbar)project was entirely based on it. Tests of electron cooling followed later: protons of 46 MeV kinetic energy were cooled with an electron beam of 26 kV and 1.3 A. The cage seen prominently in the foreground houses the HV equipment, adjacent to the "cooler" installed in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7908242.

  4. Passive Two-Phase Cooling of Automotive Power Electronics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, G.; Jeffers, J. R.; Narumanchi, S.; Bennion, K.

    2014-08-01

    Experiments were conducted to evaluate the use of a passive two-phase cooling strategy as a means of cooling automotive power electronics. The proposed cooling approach utilizes an indirect cooling configuration to alleviate some reliability concerns and to allow the use of conventional power modules. An inverter-scale proof-of-concept cooling system was fabricated, and tests were conducted using the refrigerants hydrofluoroolefin HFO-1234yf and hydrofluorocarbon HFC-245fa. Results demonstrated that the system can dissipate at least 3.5 kW of heat with 250 cm3 of HFC-245fa. An advanced evaporator design that incorporates features to improve performance and reduce size was conceived. Simulation results indicate its thermal resistance can be 37% to 48% lower than automotive dual side cooled power modules. Tests were also conducted to measure the thermal performance of two air-cooled condensers--plain and rifled finned tube designs. The results combined with some analysis were then used to estimate the required condenser size per operating conditions and maximum allowable system (i.e., vapor and liquid) temperatures.

  5. Lysozyme pattern formation in evaporating droplets

    Science.gov (United States)

    Gorr, Heather Meloy

    Liquid droplets containing suspended particles deposited on a solid, flat surface generally form ring-like structures due to the redistribution of solute during evaporation (the "coffee ring effect"). The forms of the deposited patterns depend on complex interactions between solute(s), solvent, and substrate in a rapidly changing, far from equilibrium system. Solute self-organization during evaporation of colloidal sessile droplets has attracted the attention of researchers over the past few decades due to a variety of technological applications. Recently, pattern formation during evaporation of various biofluids has been studied due to potential applications in medical screening and diagnosis. Due to the complexity of 'real' biological fluids and other multicomponent systems, a comprehensive understanding of pattern formation during droplet evaporation of these fluids is lacking. In this PhD dissertation, the morphology of the patterns remaining after evaporation of droplets of a simplified model biological fluid (aqueous lysozyme solutions + NaCl) are examined by atomic force microscopy (AFM) and optical microscopy. Lysozyme is a globular protein found in high concentration, for example, in human tears and saliva. The drop diameters, D, studied range from the micro- to the macro- scale (1 microm -- 2 mm). In this work, the effect of evaporation conditions, solution chemistry, and heat transfer within the droplet on pattern formation is examined. In micro-scale deposits of aqueous lysozyme solutions (1 microm < D < 50 microm), the protein motion and the resulting dried residue morphology are highly influenced by the decreased evaporation time of the drop. The effect of electrolytes on pattern formation is also investigated by adding varying concentrations NaCl to the lysozyme solutions. Finally, a novel pattern recognition program is described and implemented which classifies deposit images by their solution chemistries. The results presented in this Ph

  6. Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop

    NARCIS (Netherlands)

    Tan, Huanshu; Tan, Huanshu; Diddens, Christian; Lv, Pengyu; Kuerten, Johannes G.M.; Zhang, Xuehua; Zhang, Xuehua; Lohse, Detlef

    2016-01-01

    Evaporating liquid droplets are omnipresent in nature and technology, such as in inkjet printing, coating, deposition of materials, medical diagnostics, agriculture, the food industry, cosmetics, or spills of liquids. Whereas the evaporation of pure liquids, liquids with dispersed particles, or even

  7. Second sector cool down

    CERN Multimedia

    2007-01-01

    At the beginning of July, cool-down is starting in the second LHC sector, sector 4-5. The cool down of sector 4-5 may occasionally generate mist at Point 4, like that produced last January (photo) during the cool-down of sector 7-8.Things are getting colder in the LHC. Sector 7-8 has been kept at 1.9 K for three weeks with excellent stability (see Bulletin No. 16-17 of 16 April 2007). The electrical tests in this sector have got opt to a successful start. At the beginning of July the cryogenic teams started to cool a second sector, sector 4-5. At Point 4 in Echenevex, where one of the LHC’s cryogenic plants is located, preparations for the first phase of the cool-down are underway. During this phase, the sector will first be cooled to 80 K (-193°C), the temperature of liquid nitrogen. As for the first sector, 1200 tonnes of liquid nitrogen will be used for the cool-down. In fact, the nitrogen circulates only at the surface in the ...

  8. Evaporation Heat Transfer of Ammonia/Water Mixtures for Plate Type Evaporator

    Science.gov (United States)

    Kushibe, Mitsuteru; Ikegami, Yasuyuki; Monde, Masanori

    The performance test of plate type evaporators was carried out. Ammonia/Water mixtures were utilized as working fluid and warm water was utilized as heat source. Five kinds of ammonia mass fraction are tested. The overall heat transfer coefficient of ammonia/water mixtures was lower than the pure ammonia in the same experimental condition. In the convection dominant region, the mean evaporation heat transfer of ammonia/water mixtures was almost the same as ammonia by considering thermophysical properties. In the region where nucleate boiling contributes to the heat transfer, the mean evaporation heat transfer coefficient was influenced of mass fraction. An empirical correlation was proposed in order to predict the mean evaporation heat transfer coefficient of ammonia/water mixtures for plate type evaporators.

  9. Two-dimensional modeling of water spray cooling in superheated steam

    Directory of Open Access Journals (Sweden)

    Ebrahimian Vahid

    2008-01-01

    Full Text Available Spray cooling of the superheated steam occurs with the interaction of many complex physical processes, such as initial droplet formation, collision, coalescence, secondary break up, evaporation, turbulence generation, and modulation, as well as turbulent mixing, heat, mass and momentum transfer in a highly non-uniform two-phase environment. While it is extremely difficult to systematically study particular effects in this complex interaction in a well defined physical experiment, the interaction is well suited for numerical studies based on advanced detailed models of all the processes involved. This paper presents results of such a numerical experiment. Cooling of the superheated steam can be applied in order to decrease the temperature of superheated steam in power plants. By spraying the cooling water into the superheated steam, the temperature of the superheated steam can be controlled. In this work, water spray cooling was modeled to investigate the influences of the droplet size, injected velocity, the pressure and velocity of the superheated steam on the evaporation of the cooling water. The results show that by increasing the diameter of the droplets, the pressure and velocity of the superheated steam, the amount of evaporation of cooling water increases. .

  10. Performance test of solar-assisted ejector cooling system

    KAUST Repository

    Huang, Bin-Juine

    2014-03-01

    A solar-assisted ejector cooling/heating system (SACH-2k) is built and test result is reported. The solar-driven ejector cooling system (ECS) is connected in series with an inverter-type air conditioner (IAC). Several advanced technologies are developed in SACH-k2, including generator liquid level control in ECS, the ECS evaporator temperature control, and optimal control of fan power in cooling tower of ECS. From the field test results, the generator liquid level control performs quite well and keeps stable performance of ejector. The ECS evaporator temperature control also performs satisfactorily to keep ejector performance normally under low or fluctuating solar radiation. The fan power control system cooling tower performs stably and reduces the power consumption dramatically without affecting the ECS performance. The test results show that the overall system COPo including power consumptions of peripheral increases from 2.94-3.3 (IAC alone) to 4.06-4.5 (SACH-k2), about 33-43%. The highest COPo is 4.5. © 2013 Elsevier Ltd and IIR. All rights reserved.

  11. Cooling methods used in the treatment of exertional heat illness.

    Science.gov (United States)

    Smith, J E

    2005-08-01

    To review the different methods of reducing body core temperature in patients with exertional heatstroke. The search strategy included articles from 1966 to July 2003 using the databases Medline and Premedline, Embase, Evidence Based Medicine (EBM) reviews, SPORTDiscus, and cross referencing the bibliographies of relevant papers. Studies were included if they contained original data on cooling times or cooling rates in patients with heat illness or normal subjects who were subjected to heat stress. In total, 17 papers were included in the analysis. From the evidence currently available, the most effective method of reducing body core temperature appears to be immersion in iced water, although the practicalities of this treatment may limit its use. Other methods include both evaporative and invasive techniques, and the use of chemical agents such as dantrolene. The main predictor of outcome in exertional heatstroke is the duration and degree of hyperthermia. Where possible, patients should be cooled using iced water immersion, but, if this is not possible, a combination of other techniques may be used to facilitate rapid cooling. There is no evidence to support the use of dantrolene in these patients. Further work should include a randomised trial comparing immersion and evaporative therapy in heatstroke patients.

  12. Cryogenic generator cooling

    Science.gov (United States)

    Eckels, P. W.; Fagan, T. J.; Parker, J. H., Jr.; Long, L. J.; Shestak, E. J.; Calfo, R. M.; Hannon, W. F.; Brown, D. B.; Barkell, J. W.; Patterson, A.

    The concept for a hydrogen cooled aluminum cryogenic generator was presented by Schlicher and Oberly in 1985. Following their lead, this paper describes the thermal design of a high voltage dc, multimegawatt generator of high power density. The rotor and stator are cooled by saturated liquid and supercritical hydrogen, respectively. The brushless exciter on the same shaft is also cooled by liquid hydrogen. Component development testing is well under way and some of the test results concerning the thermohydraulic performance of the conductors are reported. The aluminum cryogenic generator's characteristics are attractive for hydrogen economy applications.

  13. An evaporation based digital microflow meter

    Science.gov (United States)

    Nie, C.; Frijns, A. J. H.; Mandamparambil, R.; Zevenbergen, M. A. G.; den Toonder, J. M. J.

    2015-11-01

    In this work, we present a digital microflow meter operating in the range 30-250 nl min-1 for water. The principle is based on determining the evaporation rate of the liquid via reading the number of wetted pore array structures in a microfluidic system, through which continuous evaporation takes place. A proof-of-principle device of the digital flow meter was designed, fabricated, and tested. The device was built on foil-based technology. In the proof-of-principle experiments, good agreement was found between set flow rates and the evaporation rates estimated from reading the number of wetted pore structures. The measurement range of the digital flow meter can be tuned and extended in a straightforward manner by changing the pore structure of the device.

  14. A Method for Estimating Potential Energy and Cost Savings for Cooling Existing Data Centers

    Energy Technology Data Exchange (ETDEWEB)

    Van Geet, Otto

    2017-04-24

    NREL has developed a methodology to prioritize which data center cooling systems could be upgraded for better efficiency based on estimated cost savings and economics. The best efficiency results are in cool or dry climates where 'free' economizer or evaporative cooling can provide most of the data center cooling. Locations with a high cost of energy and facilities with high power usage effectiveness (PUE) are also good candidates for data center cooling system upgrades. In one case study of a major cable provider's data centers, most of the sites studied had opportunities for cost-effective cooling system upgrades with payback period of 5 years or less. If the cable provider invested in all opportunities for upgrades with payback periods of less than 15 years, it could save 27% on annual energy costs.

  15. Concept of the Cooling System of the ITS for ALICE: Technical Proposals, Theoretical Estimates, Experimental Results

    CERN Document Server

    Godisov, O N; Yudkin, M I; Gerasimov, S F; Feofilov, G A

    1994-01-01

    Contradictory demands raised by the application of different types of sensitive detectors in 5 layers of the Inner Tracking System (ITS) for ALICE stipulate the simultaneous use of different schemes of heat drain: gaseous cooling of the 1st layer (uniform heat production over the sensitive surface) and evaporative cooling for the 2nd-5th layers (localised heat production). The last system is also a must for the thermostabilization of Si-drift detectors within 0.1 degree C. Theoretical estimates of gaseous, evaporative and liquid cooling systems are done for all ITS layers. The results of the experiments done for evaporative and liquid heat drain systems are presented and discussed. The major technical problems of the evaporative systems' design are being considered: i) control of liquid supply; ii) vapour pressure control. Two concepts of the evaporative systems are proposed: 1) One channel system for joint transfer of two phases (liquid + gas); 2) Two channels system with separate transfer of phases. Both sy...

  16. Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop

    Science.gov (United States)

    Li, D.; Ning, Z. J.; Huang, Y.; Zhang, Q. M.

    2017-05-01

    We explore the temporal relationship between microwave/hard X-ray (HXR) emission and Doppler velocity during the impulsive phase of a solar flare on 2014 October 27 (SOL2014-10-27) that displays a pulse on the light curves in the microwave (34 GHz) and HXR (25-50 keV) bands before the flare maximum. Imaging observation shows that this pulse mainly comes from one footpoint of a solar flare loop. The slit of the Interface Region Imaging Spectrograph (IRIS) stays at this footpoint during this solar flare. The Doppler velocities of Fe xxi 1354.09 Å and Si iv 1402.77 Å are extracted from the Gaussian fitting method. We find that the hot line of Fe xxi 1354.09 Å (log T ˜ 7.05) in the corona exhibits blueshift, while the cool line of Si iv 1402.77 Å (log T ˜ 4.8) in the transition region exhibits redshift, indicating explosive chromospheric evaporation. Evaporative upflows along the flare loop are also observed in the AIA 131 Å image. To our knowledge, this is the first report of chromospheric evaporation evidence from both spectral and imaging observations in the same flare. Both microwave and HXR pulses are well correlated with the Doppler velocities, suggesting that the chromospheric evaporation is driven by nonthermal electrons around this footpoint of a solar flare loop.

  17. Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Ning, Z. J.; Huang, Y.; Zhang, Q. M., E-mail: lidong@pmo.ac.cn [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS, Nanjing 210008 (China)

    2017-05-20

    We explore the temporal relationship between microwave/hard X-ray (HXR) emission and Doppler velocity during the impulsive phase of a solar flare on 2014 October 27 (SOL2014-10-27) that displays a pulse on the light curves in the microwave (34 GHz) and HXR (25–50 keV) bands before the flare maximum. Imaging observation shows that this pulse mainly comes from one footpoint of a solar flare loop. The slit of the Interface Region Imaging Spectrograph ( IRIS ) stays at this footpoint during this solar flare. The Doppler velocities of Fe xxi 1354.09 Å and Si iv 1402.77 Å are extracted from the Gaussian fitting method. We find that the hot line of Fe xxi 1354.09 Å (log T ∼ 7.05) in the corona exhibits blueshift, while the cool line of Si iv 1402.77 Å (log T ∼ 4.8) in the transition region exhibits redshift, indicating explosive chromospheric evaporation. Evaporative upflows along the flare loop are also observed in the AIA 131 Å image. To our knowledge, this is the first report of chromospheric evaporation evidence from both spectral and imaging observations in the same flare. Both microwave and HXR pulses are well correlated with the Doppler velocities, suggesting that the chromospheric evaporation is driven by nonthermal electrons around this footpoint of a solar flare loop.

  18. Modelling the Evaporation Rate in an Impingement Jet Dryer with Multiple Nozzles

    Directory of Open Access Journals (Sweden)

    Anna-Lena Ljung

    2017-01-01

    Full Text Available Impinging jets are often used in industry to dry, cool, or heat items. In this work, a two-dimensional Computational Fluid Dynamics model is created to model an impingement jet dryer with a total of 9 pairs of nozzles that dries sheets of metal. Different methods to model the evaporation rate are studied, as well as the influence of recirculating the outlet air. For the studied conditions, the simulations show that the difference in evaporation rate between single- and two-component treatment of moist air is only around 5%, hence indicating that drying can be predicted with a simplified model where vapor is included as a nonreacting scalar. Furthermore, the humidity of the inlet air, as determined from the degree of recirculating outlet air, has a strong effect on the water evaporation rate. Results show that the metal sheet is dry at the exit if 85% of the air is recirculated, while approximately only 60% of the water has evaporated at a recirculation of 92,5%.

  19. Sustainable Air Handling by Evaporation and Adsorption

    NARCIS (Netherlands)

    Esfandiari Nia, F.

    2011-01-01

    A considerable fraction of today's energy consumption is due to air-conditioning of buildings, involving both heating and cooling. Energy cost and environmental concerns force designers to find sustainable solutions. Desiccant cooling as a sustainable technology is attractive to be investigated for

  20. Black hole evaporation in conformal gravity

    Science.gov (United States)

    Bambi, Cosimo; Modesto, Leonardo; Porey, Shiladitya; Rachwał, Lesław

    2017-09-01

    We study the formation and the evaporation of a spherically symmetric black hole in conformal gravity. From the collapse of a spherically symmetric thin shell of radiation, we find a singularity-free non-rotating black hole. This black hole has the same Hawking temperature as a Schwarzschild black hole with the same mass, and it completely evaporates either in a finite or in an infinite time, depending on the ensemble. We consider the analysis both in the canonical and in the micro-canonical statistical ensembles. Last, we discuss the corresponding Penrose diagram of this physical process.

  1. LHC cooling gains ground

    CERN Multimedia

    Huillet-Miraton Catherine

    The nominal cryogenic conditions of 1.9 K have been achieved in sectors 5-6 and 7-8. This means that a quarter of the machine has reached the nominal conditions for LHC operation, having attained a temperature of below 2 K (-271°C), which is colder than interstellar space! Elsewhere, the cryogenic system in Sector 8-1 has been filled with liquid helium and cooled to 2K and will soon be available for magnet testing. Sectors 6-7 and 2-3 are being cooled down and cool-down operations have started in Sector 3-4. Finally, preparations are in hand for the cool-down of Sector 1-2 in May and of Sector 4-5, which is currently being consolidated. The LHC should be completely cold for the summer. For more information: http://lhc.web.cern.ch/lhc/Cooldown_status.htm.

  2. Warm and Cool Dinosaurs.

    Science.gov (United States)

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  3. Cooling of wood briquettes

    Directory of Open Access Journals (Sweden)

    Adžić Miroljub M.

    2013-01-01

    Full Text Available This paper is concerned with the experimental research of surface temperature of wood briquettes during cooling phase along the cooling line. The cooling phase is an important part of the briquette production technology. It should be performed with care, otherwise the quality of briquettes could deteriorate and possible changes of combustion characteristics of briquettes could happen. The briquette surface temperature was measured with an IR camera and a surface temperature probe at 42 sections. It was found that the temperature of briquette surface dropped from 68 to 34°C after 7 minutes spent at the cooling line. The temperature at the center of briquette, during the 6 hour storage, decreased to 38°C.

  4. Heat transfer model of runout table cooling: A fundamental approach

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, V.H.; Samarasekera, I.V.; Brimacombe, J.K. [Univ. of British Columbia, Vancouver, British Columbia (Canada). Centre for Metallurgical Process Engineering

    1994-12-31

    It is well known that the cooling of hot-rolled steel on the runout table is a determining factor to the final properties of the steel produced. Smaller final ferrite grain size, combined with precipitation strengthening, obtained at high cooling rates, allows lower carbon steels to achieve higher mechanical properties and better weldability and toughness. Here, a semi-theoretical model for jet impingement, and parallel flow boiling curves were developed to compute the strip temperature during cooling on the runout table. Comparison of model predictions with pilot-plant and fullscale measurements is satisfactory. Insight into the fundamental evaporation mechanisms is presented. Variables such as water temperature and flow rate, strip temperature and speed are considered.

  5. Distributed Cooling in Cryogenics with Miniaturized Fluid Circuits

    CERN Document Server

    Grohmann, Steffen

    This work presents the development of miniaturized cryogenic fluid circuits for cooling of low temperature tracking detectors in High Energy Physics (HEPI. The system development comprises the circuit layout and control, and the design of major circuit components. It includes the development of a prototype cryogenic micropump compatible with cooling powers of about l0 W to l00 W, and capable of producing pressure heads of several bars. Focus is given to the design of microtube heat exchangers for direct evaporative cooling of sensors and electronic devices. Extensive experimental investigations on heat transfer in microtubes of 250 $\\mu m$ and 500 $\\mu m$ diameter are presented, carried out with argon at about 120 K. A new relative roughness parameter is introduced to model the effect of macroscopic surface roughness on convective heat transfer. An extension of the diameter function in the VDI Heat Atlas correlation for nucleate boiling in vertical tubes is proposed. Besides HEP, potential applications are es...

  6. Efficient energy storage in liquid desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Hublitz, Astrid

    2008-07-18

    Liquid Desiccant Cooling Systems (LDCS) are open loop sorption systems for air conditioning that use a liquid desiccant such as a concentrated salt solution to dehumidify the outside air and cool it by evaporative cooling. Thermochemical energy storage in the concentrated liquid desiccant can bridge power mismatches between demand and supply. Low-flow LDCS provide high energy storage capacities but are not a state-of-the-art technology yet. The key challenge remains the uniform distribution of the liquid desiccant on the heat and mass transfer surfaces. The present research analyzes the factors of influence on the energy storage capacity by simulation of the heat and mass transfer processes and specifies performance goals for the distribution of the process media. Consequently, a distribution device for the liquid desiccant is developed that reliably meets the performance goals. (orig.)

  7. Addressing Water Consumption of Evaporative Coolers with Greywater

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Rashmi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shah, Nihar [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Phadke, Amol [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-07-01

    Evaporative coolers (ECs) provide significant gains in energy efficiency compared to vapor compression air conditioners, but simultaneously have significant onsite water demand. This can be a major barrier to deployment in areas of the world with hot and arid climates. To address this concern, this study determined where in the world evaporative cooling is suitable, the water consumption of ECs in these cities, and the potential that greywater can be used reduce the consumption of potable water in ECs. ECs covered 69percent of the cities where room air conditioners are may be deployed, based on comfort conditions alone. The average water consumption due to ECs was found to be 400 L/household/day in the United States and Australia, with the potential for greywater to provide 50percent this amount. In the rest of the world, the average water consumption was 250 L/household/day, with the potential for greywater to supply 80percent of this amount. Home size was the main factor that contributed to this difference. In the Mediterranean, the Middle East, Northern India, and the Midwestern and Southwestern United States alkalinity levels are high and water used for bleeding will likely contribute significantly to EC water consumption. Although technically feasible, upfront costs for household GW systems are currently high. In both developed and developing parts of the world, however, a direct EC and GW system is cost competitive with conventional vapor compression air conditioners. Moreover, in regions of the world that face problems of water scarcity the benefits can substantially outweigh the costs.

  8. Comparative study of two different evaporative systems: an indirect evaporative cooler and a semi-indirect ceramic evaporative cooler

    Energy Technology Data Exchange (ETDEWEB)

    Rey Martinez, F.J.; Velasco Gomez, E.; Herrero Martin, R.; Martinez Gutierrez, J.; Varela Diez, F. [University of Valladolid (Spain). Thermal Engineering Group

    2004-07-01

    In the current work, two different types of evaporative systems are shown. A returning air recovery system is used. The indirect systems have two independent airflows, the primary airstream is used to refrigerate and the secondary flow is in direct contact with water in order to improve heat and mass transfer. The first equipment (the indirect evaporative refrigerator) works like a flat interchanger made of aluminium and there is only heat transfer in the primary airflow. The second equipment (the semi-indirect evaporative refrigerator) is made of solid porous ceramic pipes, which separate the two airstreams, thus allowing that, in the primary airflow (apart from the heat transfer), there is also a mass transfer. It should also be mentioned that this system is free of legionella, because the pipes perform the role of a filter material, making it impossible for the bacterium to enter premises. This system has been named a semi-indirect evaporative system due to the permeability of the porous pipes, which allow a higher or lower water diffusion and therefore a mass transfer depending on the specific humidity of the primary airstream. (author)

  9. Cooling tower waste reduction

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, S.J.; Celeste, J.; Chine, R.; Scott, C.

    1998-05-01

    At Lawrence Livermore National Laboratory (LLNL), the two main cooling tower systems (central and northwest) were upgraded during the summer of 1997 to reduce the generation of hazardous waste. In 1996, these two tower systems generated approximately 135,400 lbs (61,400 kg) of hazardous sludge, which is more than 90 percent of the hazardous waste for the site annually. At both, wet decks (cascade reservoirs) were covered to block sunlight. Covering the cascade reservoirs reduced the amount of chemical conditioners (e.g. algaecide and biocide), required and in turn the amount of waste generated was reduced. Additionally, at the northwest cooling tower system, a sand filtration system was installed to allow cyclical filtering and backflushing, and new pumps, piping, and spray nozzles were installed to increase agitation. the appurtenance upgrade increased the efficiency of the cooling towers. The sand filtration system at the northwest cooling tower system enables operators to continuously maintain the cooling tower water quality without taking the towers out of service. Operational costs (including waste handling and disposal) and maintenance activities are compared for the cooling towers before and after upgrades. Additionally, the effectiveness of the sand filter system in conjunction with the wet deck covers (northwest cooling tower system), versus the cascade reservoir covers alone (south cooling tower south) is discussed. the overall expected return on investment is calculated to be in excess of 250 percent. this upgrade has been incorporated into the 1998 DOE complex-wide water conservation project being led by Sandia National Laboratory/Albuquerque.

  10. Laser cooling of solids

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM

    2008-01-01

    We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.

  11. Stacking with Stochastic Cooling

    CERN Document Server

    Caspers, Friedhelm

    2004-01-01

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles seen by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly protected from the Schottky noise of the stack. Vice versa the stack has to be efficiently shielded against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105, the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters)....

  12. Optimization of transfer of laser-cooled atom cloud to a quadrupole ...

    Indian Academy of Sciences (India)

    2014-02-08

    Feb 8, 2014 ... Since further adiabatic compression of the trap conserves the phase-space density (D), the optimized D obtained at the time of switching the trap can be preserved as initial phase-space density for evaporative cooling process. We performed experiments on a double-MOT set-up designed for BEC of 87Rb ...

  13. Convective instability of sludge storage under evaporation and solar radiation

    Science.gov (United States)

    Tsiberkin, Kirill; Tatyana, Lyubimova

    2014-05-01

    The sludge storages are an important part of production cycle at salt manufacturing, water supply, etc. A quality of water in the storage depends on mixing of pure water and settled sediment. One of the leading factors is thermal convection. There are two main mechanisms of the layer instability exist. First, it is instability of water due to evaporation from the free surface [1]. It cools the water from upside, increases the particles concentration and leads to the instability in the near-surface layer. Second, the sediment absorbs a solar radiation and heats the liquid from below making it unstable in the near-bottom area. We assume the initial state is the mechanical equilibrium. The water and sediment particles are motionless, the sediment forms a uniform sludge layer of thickness z0, there are no evaporation and heating by solar energy, and the temperature has a linear profile is determined by fixed upper and bottom temperatures of the layer. Taking into account the evaporation and solar radiation absorption, we obtain a non-stationary solution for the temperature using Fourier series method. The local temperature gradients increases rapidly with time, and local Rayleigh number can be estimated by thermal conduction length Lt: Raloc(z,t) = gβ(δT(z,t)/δz)L4t-/νΞ , Lt ~ √Ξt, (1) where g is gravity acceleration, β, ν and Ξ are thermal volume expansion coefficient, kinematic viscosity and thermal conductivity of the liquid, respectively. Raloc* reaches the critical value at finite time t* and water motion begins. The maximal power of solar radiation in visible band equals 230 Wt/m2 at the latitude of "Uralkalii" salt manufacturer (Berezniki, Perm Region, Russian Federation). We neglect IR and UV radiation because of its huge absorption by water [2]. The evaporation speed is found using results for shallow water reservoir [3] and meteorological data for Berezniki [4]. We get the t*~ 6 · 102 s (10 min) for the layer of 1 m depth and t*~ 2 · 103 s (40

  14. PERFORMANCE EVALUATION OF CEILING RADIANT COOLING SYSTEM IN COMPOSITE CLIMATE

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anuj [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

    2015-01-01

    Radiant cooling systems are proving to be an energy efficient solution due to higher thermal capacity of cooling fluid especially for the buildings that require individual zone controls and where the latent loads are moderate. The Conventional air conditioners work at very low temperature i.e.5-8 c (refrigerant evaporator inlet) while the radiant cooling systems, also referred as high temperature cooling system, work at high temperatures i.e. 14-18 c. The radiant cooling systems can maintain lower MRT (Mean Radiant Temperature) as ceiling panels maintain uniform temperature gradient inside room and provide higher human comfort. The radiant cooling systems are relatively new systems and their operation and energy savings potential are not quantified for a large number of buildings and operational parameters. Moreover, there are only limited numbers of whole building simulation studies have been carried out for these systems to have a full confidence in the capability of modelling tools to simulate these systems and predict the impact of various operating parameters. Theoretically, savings achieve due to higher temperature set point of chilled water, which reduces chiller-running time. However, conventional air conditioner runs continuously to maintain requisite temperature. In this paper, experimental study for performance evaluation of radiant cooling system carried out on system installed at Malaviya National Institute of Technology Jaipur. This paper quantifies the energy savings opportunities and effective temperature by radiant cooling system at different chilled water flow rates and temperature range. The data collected/ analysed through experimental study will used for calibration and validation of system model of building prepared in building performance simulation software. This validated model used for exploring optimized combinations of key parameters for composite climate. These optimized combinations will used in formulation of radiant cooling system

  15. The energy balance within a bubble column evaporator

    Science.gov (United States)

    Fan, Chao; Shahid, Muhammad; Pashley, Richard M.

    2017-11-01

    Bubble column evaporator (BCE) systems have been studied and developed for many applications, such as thermal desalination, sterilization, evaporative cooling and controlled precipitation. The heat supplied from warm/hot dry bubbles is to vaporize the water in various salt solutions until the solution temperature reaches steady state, which was derived into the energy balance of the BCE. The energy balance and utilization involved in each BCE process form the fundamental theory of these applications. More importantly, it opened a new field for the thermodynamics study in the form of heat and vapor transfer in the bubbles. In this paper, the originally derived energy balance was reviewed on the basis of its physics in the BCE process and compared with new proposed energy balance equations in terms of obtained the enthalpy of vaporization (ΔH vap) values of salt solutions from BCE experiments. Based on the analysis of derivation and ΔH vap values comparison, it is demonstrated that the original balance equation has high accuracy and precision, within 2% over 19-55 °C using improved systems. Also, the experimental and theoretical techniques used for determining ΔH vap values of salt solutions were reviewed for the operation conditions and their accuracies compared to the literature data. The BCE method, as one of the most simple and accurate techniques, offers a novel way to determine ΔH vap values of salt solutions based on its energy balance equation, which had error less than 3%. The thermal energy required to heat the inlet gas, the energy used for water evaporation in the BCE and the energy conserved from water vapor condensation were estimated in an overall energy balance analysis. The good agreement observed between input and potential vapor condensation energy illustrates the efficiency of the BCE system. Typical energy consumption levels for thermal desalination for producing pure water using the BCE process was also analyzed for different inlet air

  16. Cool Flame Quenching

    Science.gov (United States)

    Pearlman, Howard; Chapek, Richard

    2001-01-01

    Cool flame quenching distances are generally presumed to be larger than those associated with hot flames, because the quenching distance scales with the inverse of the flame propagation speed, and cool flame propagation speeds are often times slower than those associated with hot flames. To date, this presumption has never been put to a rigorous test, because unstirred, non-isothermal cool flame studies on Earth are complicated by natural convection. Moreover, the critical Peclet number (Pe) for quenching of cool flames has never been established and may not be the same as that associated with wall quenching due to conduction heat loss in hot flames, Pe approx. = 40-60. The objectives of this ground-based study are to: (1) better understand the role of conduction heat loss and species diffusion on cool flame quenching (i.e., Lewis number effects), (2) determine cool flame quenching distances (i.e, critical Peclet number, Pe) for different experimental parameters and vessel surface pretreatments, and (3) understand the mechanisms that govern the quenching distances in premixtures that support cool flames as well as hot flames induced by spark-ignition. Objective (3) poses a unique fire safety hazard if conditions exist where cool flame quenching distances are smaller than those associated with hot flames. For example, a significant, yet unexplored risk, can occur if a multi-stage ignition (a cool flame that transitions to a hot flame) occurs in a vessel size that is smaller than that associated with the hot quenching distance. To accomplish the above objectives, a variety of hydrocarbon-air mixtures will be tested in a static reactor at elevated temperature in the laboratory (1g). In addition, reactions with chemical induction times that are sufficiently short will be tested aboard NASA's KC-135 microgravity (mu-g) aircraft. The mu-g results will be compared to a numerical model that includes species diffusion, heat conduction, and a skeletal kinetic mechanism

  17. Sequence crystallization during isotherm evaporation of southern ...

    African Journals Online (AJOL)

    Sequence crystallization during isotherm evaporation of southern Algeria chott Baghdad natural brine. M Zatout, M Hacini, A.H. Hamzaoui, A M'nif. Abstract. Southern Algerian's natural brine sampled from chott Baghdad may be a source of mineral salts with a high economic value. These salts are recoverable by simple ...

  18. Control of evaporating complex fluids through electrowetting

    NARCIS (Netherlands)

    Mampallil Augustine, Dileep; Eral, Burak; van den Ende, Henricus T.M.; Mugele, Friedrich Gunther

    2012-01-01

    Evaporating drops of complex fluids such as colloidal suspensions and macromolecular solutions typically leave behind ring-shaped solid residues commonly known as coffee stains. Electrowetting-driven microfluidic flows allow for controlling this process. We present coffee stain suppression for

  19. Evaporative Lithography in Open Microfluidic Channel Networks

    KAUST Repository

    Lone, Saifullah

    2017-02-24

    We demonstrate a direct capillary-driven method based on wetting and evaporation of various suspensions to fabricate regular two-dimensional wires in an open microfluidic channel through continuous deposition of micro- or nanoparticles under evaporative lithography, akin to the coffee-ring effect. The suspension is gently placed in a loading reservoir connected to the main open microchannel groove on a PDMS substrate. Hydrophilic conditions ensure rapid spreading of the suspension from the loading reservoir to fill the entire channel length. Evaporation during the spreading and after the channel is full increases the particle concentration toward the end of the channel. This evaporation-induced convective transport brings particles from the loading reservoir toward the channel end where this flow deposits a continuous multilayered particle structure. The particle deposition front propagates backward over the entire channel length. The final dry deposit of the particles is thereby much thicker than the initial volume fraction of the suspension. The deposition depth is characterized using a 3D imaging profiler, whereas the deposition topography is revealed using a scanning electron microscope. The patterning technology described here is robust and passive and hence operates without an external field. This work may well become a launching pad to construct low-cost and large-scale thin optoelectronic films with variable thicknesses and interspacing distances.

  20. Intrinsic Angular Investigations on Metal Evaporated Tapes

    NARCIS (Netherlands)

    Samwel, E.O.; Samwel, E.O.; Bijl, D.B.; Lodder, J.C.; Popma, T.J.A.

    1996-01-01

    Demagnetisation compensated torque- and angle-dependent remanence measurements are presented on commercial and experimental metal evaporated tapes. The latter have been prepared in our laboratory on a mini-roll coater system. From these results the easy axes have been determined.

  1. Transhorizon Radiowave Propagation due to Evaporation Ducting ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 1. Transhorizon Radiowave Propagation due to Evaporation Ducting - The Effect of Tropospheric Weather Conditions on VHF and UHF Radio Paths Over the Sea. Salil David Gunashekar D R Siddle E M Warrington. General Article Volume 11 ...

  2. Spontaneous evaporation of the acetone drop

    Science.gov (United States)

    Dunin, S. Z.; Nagornov, O. V.

    2017-12-01

    The exact solution of the problem on evaporation of the acetone sessile drop at solid substrate is derived. The solution allows us to analyze the temperature field behavior at various thermodynamic parameters. The Marangoni forces are calculated in explicit form. The solution can be used to check numerical approaches for similar problems.

  3. Evaporative Lithography in Open Microfluidic Channel Networks.

    Science.gov (United States)

    Lone, Saifullah; Zhang, Jia Ming; Vakarelski, Ivan U; Li, Er Qiang; Thoroddsen, Sigurdur T

    2017-03-21

    We demonstrate a direct capillary-driven method based on wetting and evaporation of various suspensions to fabricate regular two-dimensional wires in an open microfluidic channel through continuous deposition of micro- or nanoparticles under evaporative lithography, akin to the coffee-ring effect. The suspension is gently placed in a loading reservoir connected to the main open microchannel groove on a PDMS substrate. Hydrophilic conditions ensure rapid spreading of the suspension from the loading reservoir to fill the entire channel length. Evaporation during the spreading and after the channel is full increases the particle concentration toward the end of the channel. This evaporation-induced convective transport brings particles from the loading reservoir toward the channel end where this flow deposits a continuous multilayered particle structure. The particle deposition front propagates backward over the entire channel length. The final dry deposit of the particles is thereby much thicker than the initial volume fraction of the suspension. The deposition depth is characterized using a 3D imaging profiler, whereas the deposition topography is revealed using a scanning electron microscope. The patterning technology described here is robust and passive and hence operates without an external field. This work may well become a launching pad to construct low-cost and large-scale thin optoelectronic films with variable thicknesses and interspacing distances.

  4. optimal evaporating and condensing temperatures of organic

    African Journals Online (AJOL)

    user

    2017-01-01

    Jan 1, 2017 ... However, the study further showed that the evaporating temperature (ET) and condensing temperature (CT) affect the thermal performance and net power output of the cycles. Dai et al.[20]conducted parametric optimisation of ORC with exergy efficiency. He et al. [21] considered the optimisation of a simple.

  5. Experiments on Evaporative Emissions in Ventilated Rooms

    DEFF Research Database (Denmark)

    Topp, Claus; Nielsen, Peter V.; Heiselberg, Per

    In many new buildings the indoor air quality is affected by emissions of volatile organic compounds (VOCs) from building materials. The emission process may be controlled either by diffusion inside the material or evaporation from the surface but it always involves mass transfer across the boundary...

  6. Evaporation Controlled Emission in Ventilated Rooms

    DEFF Research Database (Denmark)

    Topp, Claus; Nielsen, Peter V.; Heiselberg, Per

    -scale ventilated room when the emission is fully or partly evaporation controlled. The objective of the present research work has been to investigate the change of emission rates from small-scale experiments to full-scale ventilated rooms and to investigate the influence of the local air velocity field near...

  7. Improving eco-sustainable characteristics and energy efficiency of evaporative fluid cooler via experimental and numerical study

    Directory of Open Access Journals (Sweden)

    Rašković Predrag O.

    2008-01-01

    Full Text Available This paper presents an on-going research project that aims to identify possibilities for wider use of evaporative cooling in process industry, especially the use of evaporative fluid cooler units. Experimental study is performed on small scale evaporative fluid cooler, while the correlation based model has been carried out to explore the detailed heat and mass transfer processes inside this unit. Numerical integration of mathematical model is executed by new approach, based on differential, collocation Simpson method. Proposed models have been verified by comparing the computed results with those obtained by the experimental measurements. The results of research will enable the creation of more comprehensive simulation software, with wider range of operating and construction parameters.

  8. Design and Modelling of Water Chilling Production System by the Combined Effects of Evaporation and Night Sky Radiation

    Directory of Open Access Journals (Sweden)

    Ahmed Y. Taha Al-Zubaydi

    2014-01-01

    Full Text Available The design and mathematical modelling of thermal radiator panel to be used primarily to measure night sky radiation wet coated surface is presented in this paper. The panel consists of an upper dry surface coated aluminium sheet laminated to an ethylene vinyl acetate foam backing block as an insulation. Water is sprayed onto the surface of the panel so that an evaporative cooling effect is gained in addition to the radiation effect; the surface of a panel then is wetted in order to study and measure the night sky radiation from the panel wet surface. In this case, the measuring water is circulated over the upper face of this panel during night time. Initial TRNSYS simulations for the performance of the system are presented and it is planned to use the panel as calibrated instruments for discriminating between the cooling effects of night sky radiation and evaporation.

  9. Evaluating the hydrological consistency of evaporation products

    KAUST Repository

    Lopez Valencia, Oliver Miguel

    2017-01-18

    Advances in space-based observations have provided the capacity to develop regional- to global-scale estimates of evaporation, offering insights into this key component of the hydrological cycle. However, the evaluation of large-scale evaporation retrievals is not a straightforward task. While a number of studies have intercompared a range of these evaporation products by examining the variance amongst them, or by comparison of pixel-scale retrievals against ground-based observations, there is a need to explore more appropriate techniques to comprehensively evaluate remote-sensing-based estimates. One possible approach is to establish the level of product agreement between related hydrological components: for instance, how well do evaporation patterns and response match with precipitation or water storage changes? To assess the suitability of this "consistency"-based approach for evaluating evaporation products, we focused our investigation on four globally distributed basins in arid and semi-arid environments, comprising the Colorado River basin, Niger River basin, Aral Sea basin, and Lake Eyre basin. In an effort to assess retrieval quality, three satellite-based global evaporation products based on different methodologies and input data, including CSIRO-PML, the MODIS Global Evapotranspiration product (MOD16), and Global Land Evaporation: the Amsterdam Methodology (GLEAM), were evaluated against rainfall data from the Global Precipitation Climatology Project (GPCP) along with Gravity Recovery and Climate Experiment (GRACE) water storage anomalies. To ensure a fair comparison, we evaluated consistency using a degree correlation approach after transforming both evaporation and precipitation data into spherical harmonics. Overall we found no persistent hydrological consistency in these dryland environments. Indeed, the degree correlation showed oscillating values between periods of low and high water storage changes, with a phase difference of about 2–3 months

  10. Evaporation characteristics of ETBE-blended gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Katsuhiro, E-mail: okamoto@nrips.go.jp [National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882 (Japan); Hiramatsu, Muneyuki [Yamanashi Prefectural Police H.Q., 312-4 Kubonakajima, Isawa-cho, Usui, Yamanashi 406-0036 (Japan); Hino, Tomonori; Otake, Takuma [Metropolitan Police Department, 2-1-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8929 (Japan); Okamoto, Takashi; Miyamoto, Hiroki; Honma, Masakatsu; Watanabe, Norimichi [National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882 (Japan)

    2015-04-28

    Highlights: • We chose 8-component hydrocarbon mixture as a model gasoline, and defined the molar mass of gasoline. • We proposed an evaporation model assuming a 2-component mixture of gasoline and ETBE. • We predicted the change in the vapor pressure of ETBE-blended gasoline by evaporation. • The vapor pressures were measured and compared as a means of verifying the model. • We presented the method for predicting flash points of the ETBE-blended gasoline. - Abstract: To reduce greenhouse gas emissions, which contribute to global warming, production of gasoline blended with ethyl tert-buthyl ether (ETBE) is increasing annually. The flash point of ETBE is higher than that of gasoline, and blending ETBE into gasoline will change the flash point and the vapor pressure. Therefore, it is expected that the fire hazard caused by ETBE-blended gasoline would differ from that caused by normal gasoline. The aim of this study was to acquire the knowledge required for estimating the fire hazard of ETBE-blended gasoline. Supposing that ETBE-blended gasoline was a two-component mixture of gasoline and ETBE, we developed a prediction model that describes the vapor pressure and flash point of ETBE-blended gasoline in an arbitrary ETBE blending ratio. We chose 8-component hydrocarbon mixture as a model gasoline, and defined the relation between molar mass of gasoline and mass loss fraction. We measured the changes in the vapor pressure and flash point of gasoline by blending ETBE and evaporation, and compared the predicted values with the measured values in order to verify the prediction model. The calculated values of vapor pressures and flash points corresponded well to the measured values. Thus, we confirmed that the change in the evaporation characteristics of ETBE-blended gasoline by evaporation could be predicted by the proposed model. Furthermore, the vapor pressure constants of ETBE-blended gasoline were obtained by the model, and then the distillation curves were

  11. Tank 26F-2F Evaporator Study

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K.

    2012-12-19

    Tank 26F supernate sample was sent by Savannah River Remediation to Savannah River National Laboratory for evaporation test to help understand the underlying cause of the recent gravity drain line (GDL) pluggage during operation of the 2F Evaporator system. The supernate sample was characterized prior to the evaporation test. The evaporation test involved boiling the supernate in an open beaker until the density of the concentrate (evaporation product) was between 1.4 to 1.5 g/mL. It was followed by filtering and washing of the precipitated solids with deionized water. The concentrate supernate (or concentrate filtrate), the damp unwashed precipitated solids, and the wash filtrates were characterized. All the precipitated solids dissolved during water washing. A semi-quantitative X-ray diffraction (XRD) analysis on the unwashed precipitated solids revealed their composition. All the compounds with the exception of silica (silicon oxide) are known to be readily soluble in water. Hence, their dissolution during water washing is not unexpected. Even though silica is a sparingly water-soluble compound, its dissolution is also not surprising. This stems from its small fraction in the solids as a whole and also its relative freshness. Assuming similar supernate characteristics, flushing the GDL with water (preferably warm) should facilitate dissolution and removal of future pluggage events as long as build up/aging of the sparingly soluble constituent (silica) is limited. On the other hand, since the amount of silica formed is relatively small, it is quite possible dissolution of the more soluble larger fraction will cause disintegration or fragmentation of the sparingly soluble smaller fraction (that may be embedded in the larger soluble solid mass) and allow its removal via suspension in the flushing water.

  12. Capillary Action may Cool Systems and Precisely balance Chemical Reactions

    Science.gov (United States)

    Kriske, Richard

    2011-10-01

    It is well known that it takes no work for Water to rise in a Capillary tube against the force of Gravity. There is a precise balance in this system that resembles Robert Millikan's ``Oil Drop'' experiment, where mass was balanced against the electrostatic force. If at the top of the capillary tube there is evaporation, one can see that the system is cooled as another water molecule has room to move up the column. Furthermore, if the evaporation process can be controlled one photon at a time, a precise balance is created between a photon, and the height/mass of the column. If other molecules are place in the column, they can be moved up and down the column, in a chromatograph way, in a fairly precise manner, by controlling evaporation and molecular weight. If in addition to all of this, the interface of the solution against the walls of the column have Fermi levels, it can be seen as a very precise Electrochemical Device. In the situation of nanotubes, as opposed to trees and plants, these properties can be used to create measure environmental properties and to Balance Chemical Reactions. Forests, and Plants may cool themselves and their environment using this process, and using this process coupled with more energetic photons through photosynthesis.

  13. Cool WISPs for stellar cooling excesses

    Science.gov (United States)

    Giannotti, Maurizio; Irastorza, Igor; Redondo, Javier; Ringwald, Andreas

    2016-05-01

    Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a mild preference for a non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP or a massless HP represent the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO and the massless HP requires a multi TeV energy scale of new physics that might be accessible at the LHC.

  14. Solenoidal ionization cooling lattices

    Directory of Open Access Journals (Sweden)

    R. C. Fernow

    2007-06-01

    Full Text Available We explore a practical approach for designing ionization cooling channels with periodic solenoidal focusing. We examine the lattice characteristics in terms of the properties of the coils and the cell geometry. The peak magnetic field in the coils is an important engineering constraint in lattice design. We examine the dependence of the peak field, momentum passband locations, and the beta function on the coil parameters. We make a systematic examination of all allowed lattice configurations taking into account the symmetry properties of the current densities and the beta function. We introduce a unique classification for comparing cooling lattice configurations. While solutions with a single coil per cell illustrate most of the effects that are important for cooling channel design, the introduction of additional coils allows more flexibility in selecting the lattice properties. We look at example solutions for the problem of the initial transverse cooling stage of a neutrino factory or muon collider and compare our results with the properties of some published cooling lattice designs. Scaling laws are used to compare solutions from different symmetry classes.

  15. Film-Evaporation MEMS Tunable Array for Picosat Propulsion and Thermal Control

    Science.gov (United States)

    Alexeenko, Alina; Cardiff, Eric; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Film-Evaporation MEMS Tunable Array (FEMTA) concept for propulsion and thermal control of picosats exploits microscale surface tension effect in conjunction with temperature- dependent vapor pressure to realize compact, tunable and low-power thermal valving system. The FEMTA is intended to be a self-contained propulsion unit requiring only a low-voltage DC power source to operate. The microfabricated thermal valving and very-high-integration level enables fast high-capacity cooling and high-resolution, low-power micropropulsion for picosats that is superior to existing smallsat micropropulsion and thermal management alternatives.

  16. A simulation for predicting potential cooling effect on LPG-fuelled vehicles

    Science.gov (United States)

    Setiyo, M.; Soeparman, S.; Wahyudi, S.; Hamidi, N.

    2016-03-01

    Liquefied Petroleum Gas vehicles (LPG Vehicles) provide a potential cooling effect about 430 kJ/kg LPG consumption. This cooling effect is obtained from the LPG phase change from liquid to vapor in the vaporizer. In the existing system, energy to evaporate LPG is obtained from the coolant which is circulated around the vaporizer. One advantage is that the LPG (70/30 propane / butane) when expanded from 8 bar to at 1.2 bar, the temperature is less than -25 °C. These conditions provide opportunities to evaporate LPG with ambient air flow, then produce a cooling effect for cooling car's cabin. In this study, some LPG mix was investigated to determine the optimum condition. A simulation was carried out to estimate potential cooling effects of 2000 cc engine from 1000 rpm to 6000 rpm. In this case, the mass flow rate of LPG is a function of fuel consumption. The simulation result shows that the LPG (70/30 propane/butane) provide the greatest cooling effect compared with other mixtures. In conclusion, the 2000 cc engine fueled LPG at 3000 rpm provides potential cooling effect more than 1.3 kW, despite in the low engine speed (1000 rpm) only provides about 0.5 kW.

  17. Monitoring Cray Cooling Systems

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Don E [ORNL; Ezell, Matthew A [ORNL; Becklehimer, Jeff [Cray, Inc.; Donovan, Matthew J [ORNL; Layton, Christopher C [ORNL

    2014-01-01

    While sites generally have systems in place to monitor the health of Cray computers themselves, often the cooling systems are ignored until a computer failure requires investigation into the source of the failure. The Liebert XDP units used to cool the Cray XE/XK models as well as the Cray proprietary cooling system used for the Cray XC30 models provide data useful for health monitoring. Unfortunately, this valuable information is often available only to custom solutions not accessible by a center-wide monitoring system or is simply ignored entirely. In this paper, methods and tools used to harvest the monitoring data available are discussed, and the implementation needed to integrate the data into a center-wide monitoring system at the Oak Ridge National Laboratory is provided.

  18. Muon ionization cooling experiment

    CERN Multimedia

    CERN. Geneva

    2003-01-01

    A neutrino factory based on a muon storage ring is the ultimate tool for studies of neutrino oscillations, including possibly leptonic CP violation. It is also the first step towards muon colliders. The performance of this new and promising line of accelerators relies heavily on the concept of ionisation cooling of minimum ionising muons, for which much R&D is required. The concept of a muon ionisation cooling experiment has been extensively studied and first steps are now being taken towards its realisation by a joint international team of accelerator and particle physicists. The aim of the workshop is to to explore at least two versions of an experiment based on existing cooling channel designs. If such an experiment is feasible, one shall then select, on the basis of effectiveness, simplicity, availability of components and overall cost, a design for the proposed experiment, and assemble the elements necessary to the presentation of a proposal. Please see workshop website.

  19. ELECTRON COOLING FOR RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI,I.; AHRENS,L.; BRENNAN,M.; HARRISON,M.; KEWISCH,J.; MACKAY,W.; PEGGS,S.; ROSER,T.; SATOGATA,T.; TRBOJEVIC,D.; YAKIMENKO,V.

    2001-06-18

    We introduce plans for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This project has a number of new features as electron coolers go: It will cool 100 GeV/nucleon ions with 50 MeV electrons; it will be the first attempt to cool a collider at storage-energy; and it will be the first cooler to use a bunched beam and a linear accelerator as the electron source. The linac will be superconducting with energy recovery. The electron source will be based on a photocathode gun. The project is carried out by the Collider-Accelerator Department at BNL in collaboration with the Budker Institute of Nuclear Physics.

  20. Steady 3D Numerical Simulation of the Evaporator and Compensation Chamber of a Loop Heat Pipe

    Directory of Open Access Journals (Sweden)

    A. V. Nedayvozov

    2017-01-01

    Full Text Available The paper presents results of a steady three-dimensional numerical simulation of a flat evaporator and compensation chamber (CC of a loop heat pipe (LHP and describes a procedure of the thermal state calculation of the evaporator and the compensation chamber.The LHP is an efficient heat transfer device operating on the principle of evaporation-condensation cycle. It is successfully used in space technology and also to cool the heat-stressed components of electronic devices and computer equipment. The authors carried out a numerical study of the influence of the condensate pipeline length, immersed in water, on the thermal state of the evaporator and the compensation chamber.  The paper shows the influence of the mass forces field on the calculation results. Presents all the numerical studies carried out by the authors for a brass flat evaporator with a thermal load of 80 W. Water is used as a LHP heat-transfer fluid. Fields of temperature, pressure and velocity are presented for each design option.Based on the calculation results, the authors came to the following conclusions:Influence of the mass forces field for the LHP of this type is significant and leads to arising water vortex flow in the condensate pipeline and CC, thereby mixing and equalizing the water temperature in the CC and in the porous element, reducing the maximum temperature of the porous element;The increasing section length of the condensate pipeline in the CC leads to increasing velocity of the heat-transfer fluid in the CC and in the porous element, decreasing mixing zone of the condensate in the CC, and increasing temperature non-uniformity of the porous element.

  1. Studies on evaporation from the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, Lakshmana G.R.; VeenaDevi, Y.; Reddy, Gopala K.; Prasad, A.L.N.

    Evaporation from the surface of the North Indian Ocean is estimated following the aerodynamic approach The influence of the southwest monsoon and the northeast monsoon is significant giving rise to maximum evaporation from the sea surface due...

  2. An Investigation of Graduate Scientists' Understandings of Evaporation and Boiling.

    Science.gov (United States)

    Goodwin, Alan; Orlik, Yuri

    2000-01-01

    Uses a video presentation of six situations relating to the evaporation and boiling of liquids and the escape of dissolved gases from solution and investigates graduate scientists' understanding of the concepts of boiling and evaporation. (Author/YDS)

  3. Cool-down and frozen start-up behavior of a grooved water heat pipe

    Science.gov (United States)

    Jang, Jong Hoon

    1990-01-01

    A grooved water heat pipe was tested to study its characteristics during the cool-down and start-up periods. The water heat pipe was cooled down from the ambient temperature to below the freezing temperature of water. During the cool-down, isothermal conditions were maintained at the evaporator and adiabatic sections until the working fluid was frozen. When water was frozen along the entire heat pipe, the heat pipe was rendered inactive. The start-up of the heat pipe from this state was studied under several different operating conditions. The results show the existence of large temperature gradients between the evaporator and the condenser, and the moving of the melting front of the working fluid along the heat pipe. Successful start-up was achieved for some test cases using partial gravity assist. The start-up behavior depended largely on the operating conditions.

  4. Personal, closed-cycle cooling and protective apparatus and thermal battery therefor

    Science.gov (United States)

    Klett, James W.; Klett, Lynn B.

    2004-07-20

    A closed-cycle apparatus for cooling a living body includes a heat pickup body or garment which permits evaporation of an evaporating fluid, transmission of the vapor to a condenser, and return of the condensate to the heat pickup body. A thermal battery cooling source is provided for removing heat from the condenser. The apparatus requires no external power and provides a cooling system for soldiers, race car drivers, police officers, firefighters, bomb squad technicians, and other personnel who may utilize protective clothing to work in hostile environments. An additional shield layer may simultaneously provide protection from discomfort, illness or injury due to harmful atmospheres, projectiles, edged weapons, impacts, explosions, heat, poisons, microbes, corrosive agents, or radiation, while simultaneously removing body heat from the wearer.

  5. How cool is Uchimizu?

    Science.gov (United States)

    Solcerova, Anna; van Emmerik, Tim; Hilgersom, Koen; van de Ven, Frans; van de Giesen, Nick

    2017-04-01

    The Urban Heat Island (UHI) was first described 200 years ago, but ways to mitigate heat in urban areas reach much further into the past. Uchimizu is a 17th century Japanese tradition, in which water is sprinkled around houses, temples, and in gardens to cool the ground surface and the air, and to settle the dust. Nowadays, megacities such as Tokyo are aiming to revive the - by modern technology suppressed - method, and uchimizu is promoted by local authorities as a "clever way to feel cool". Unfortunately, the number of published studies that have quantified the cooling effects of uchimizu is limited, and only uses measurements of the surface temperature, or air temperature at a single height, as a measure of the cooling effect. In this research a dense 3D Distributed Temperature Sensing (DTS) setup was used to measure air temperature within once cubic meter of air above an urban surface with high spatial and temporal resolution. Six experiments were performed to systematically study the effect of (1) applied water amount, (2) initial surface temperature, and (3) shading on the cooling effect of uchimizu. We present the results and the subsequent analyses of these experiments, done during summer in Delft, The Netherlands. We show that this simple water sprinkling method has the potential to decrease extreme temperatures in impervious and paved parts of urban areas considerably. Besides mitigating the UHI, uchimizu practice is also an opportunity to increase awareness among citizens, and stimulate citizen participation in solving heat stress problems and energy saving. By providing refreshing insights on the cooling effect of uchimizu, we aim to contribute to the modern revival of this old tradition.

  6. Superconductor rotor cooling system

    Science.gov (United States)

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

    2002-01-01

    A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

  7. Evaporative cooling with sprinklers to reduce heat-related fruit damage in northern highbush blueberry

    Science.gov (United States)

    Hot and sunny weather can cause a considerable amount of fruit damage in blueberries and results in millions of dollars of crop loss each year. The objective of this study was to evaluate the efficacy of using sprinklers to reduce the damage. The study was conducted for 2 years in a mature planting ...

  8. Development and test of the CO2 evaporative cooling system for the LHCb UT Detector

    CERN Multimedia

    Coelli, Simone

    2016-01-01

    The upgrade of the LHCb detector, which will take place during the Long Shutdown 2 from mid 2018 to the end of 2019, will extend significantly the physics reach of the experiment by allowing it to run at higher instantaneous luminosity with increased trigger efficiency for a wide range of decay channels. The LHCb upgrade relies on two major changes. Firstly, the full read-out of the front-end electronics, currently limited by a Level-0 trigger to 1 MHz, will be replaced with a 40 MHz trigger system. Secondly, the upgraded LHCb detector will be designed to cope with an increase of the nominal operational luminosity by a factor five compared to the current detector. Compared to the current experiment several subsystems need to be partially rebuilt. Among these the 4 TT planes will be replaced by new high granularity silicon micro-strip planes with an improved coverage of the LHCb acceptance.The new system is called the Upstream Tracker. The radiation length of each UT plane should not exceed the value of 1 % X0...

  9. Non-Evaporative Cooling via Inelastic Collisions in an Optical Trap

    Science.gov (United States)

    2013-02-28

    Wei-Ting Chen, and Jacob L. Roberts, Density-dependent response of an ultracold plasma to few-cycle radio -frequency pulses, Phys. Rev. A 87, 013410...electron Bohr magneton, B is the magnitude of the externally applied magnetic field, and ħωF is equal to the energy difference between the F=1 and F=2...response of an ultracold plasma to few-cycle radio -frequency pulses, Phys. Rev. A 87, 013410 (2013). The density of a UCP is a critical parameter that is

  10. Evaporation from the shallow Lake Massaciuccoli (Tuscany, Italy) studied using stable isotopes and evaporation pan data

    Science.gov (United States)

    Baneschi, I.; Gonfiantini, R.; Guidi, M.

    2009-04-01

    Oxygen and hydrogen isotope variations monitored in Lake Massaciuccoli (7 km2, 2 m deep, seasonally variable water level) during summer 2008, were compared with those observed in a Class A evaporation pan (diameter 120.6 cm, depth 25.4 cm) placed on the lake eastern shore. Air temperature, pressure, relative humidity, wind speed and direction, solar radiation, water temperature in the lake and the pan were also measured. The pluviometer indicated that no precipitation occurred during the study period. The pan was initially filled with groundwater up to the level of 19.2 cm (219 L), depleted in heavy isotopes with respect to tha lake water. Sodium chloride was added up to the concentration of 1 g×L-1, which is assumed do not affect significantly the evaporation rate till the water volume is reduced to less than 10 %. The Cl- concentration was used to provide an estimation of the evaporated water fraction, in addition to the micrometer measuring the water level variations. The pan water was sampled every 2-3 days and Cl- and stable isotopes determined. The set of stable isotope and evaporation data enabled us to compute the parameters governing the evaporation process and the isotopic exchanges with the atmospheric moisture, according to the procedure proposed by Gonfiantini (1986). The values were applied to test three working hypotheses of water balance of Lake Massaciuccoli: (i) surface inflow and outflow of liquid water are negligible and only evaporation is important; (ii) the inflow is negligible and outflow and evaporation are both significant; (iii) the three terms of balance are all important but the losses by evaporation and outflow exceed inflow (as the lake water level was decreasing). Water exchanges with groundwater are considered negligible. The best agreement between lake and pan data was obtained with the second hypothesis, for which the fraction of water removed by evaporation was estimated to be about 40 % ot he total water losses. This residual

  11. Determination of clothing evaporative resistance on a sweating thermal manikin in an isothermal condition: heat loss method or mass loss method?

    Science.gov (United States)

    Wang, Faming; Gao, Chuansi; Kuklane, Kalev; Holmér, Ingvar

    2011-08-01

    This paper addresses selection between two calculation options, i.e heat loss option and mass loss option, for thermal manikin measurements on clothing evaporative resistance conducted in an isothermal condition (T(manikin) = T(a) = T(r)). Five vocational clothing ensembles with a thermal insulation range of 1.05-2.58 clo were selected and measured on a sweating thermal manikin 'Tore'. The reasons why the isothermal heat loss method generates a higher evaporative resistance than that of the mass loss method were thoroughly investigated. In addition, an indirect approach was applied to determine the amount of evaporative heat energy taken from the environment. It was found that clothing evaporative resistance values by the heat loss option were 11.2-37.1% greater than those based on the mass loss option. The percentage of evaporative heat loss taken from the environment (H(e,env)) for all test scenarios ranged from 10.9 to 23.8%. The real evaporative cooling efficiency ranged from 0.762 to 0.891, respectively. Furthermore, it is evident that the evaporative heat loss difference introduced by those two options was equal to the heat energy taken from the environment. In order to eliminate the combined effects of dry heat transfer, condensation, and heat pipe on clothing evaporative resistance, it is suggested that manikin measurements on the determination of clothing evaporative resistance should be performed in an isothermal condition. Moreover, the mass loss method should be applied to calculate clothing evaporative resistance. The isothermal heat loss method would appear to overestimate heat stress and thus should be corrected before use.

  12. 7 CFR 58.913 - Evaporators and vacuum pans.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Evaporators and vacuum pans. 58.913 Section 58.913....913 Evaporators and vacuum pans. All equipment used in the removal of moisture from milk or milk... Sanitary Standards for Milk and Milk Products Evaporators and Vacuum Pans. ...

  13. Modeling of Evaporation Losses in Sewage Sludge Drying Bed ...

    African Journals Online (AJOL)

    Modeling of Evaporation Losses in Sewage Sludge Drying Bed. JI Obianyo, JC Agunwamba. Abstract. A model for evaporation losses in sewage sludge drying bed was derived from first principles. This model was developed based on the reasoning that the rate at which evaporation is taking place is directly proportional to ...

  14. Method of freshening salt water in a saline evaporator

    Energy Technology Data Exchange (ETDEWEB)

    Khalikov, T.T.

    1982-01-01

    A method is described for freshening salt water in a saline evaporator by heating the water, blowing the evaporation surface with air and condensation of the distillate. In order to reduce heat losses in the air freshener before blowing, the evaporation surfaces are preliminarily heated.

  15. Thermodynamic Modeling of Savannah River Evaporators

    Energy Technology Data Exchange (ETDEWEB)

    Weber, C.F.

    2001-08-02

    A thermodynamic model based on the code SOLGASMIX is developed to calculate phase equilibrium in evaporators and related tank wastes at the Savannah River Site (SRS). This model uses the Pitzer method to calculate activity coefficients, and many of the required Pitzer parameters have been determined in the course of this work. Principal chemical species in standard SRS simulant solutions are included, and the temperature range for most parameters has been extended above 100 C. The SOLGASMIX model and calculations using the code Geochemists Workbench are compared to actual solubility data including silicate, aluminate, and aluminosilicate solutions. In addition, SOLGASMIX model calculations are also compared to transient solubility data involving SRS simulant solutions. These comparisons indicate that the SOLGASMIX predictions closely match reliable data over the range of temperature and solution composition expected in the SRS evaporator and related tanks. Predictions using the Geochemists Workbench may be unreliable, due primarily to the use of an inaccurate activity coefficient model.

  16. Black hole evaporation rates without spacetime.

    Science.gov (United States)

    Braunstein, Samuel L; Patra, Manas K

    2011-08-12

    Verlinde recently suggested that gravity, inertia, and even spacetime may be emergent properties of an underlying thermodynamic theory. This vision was motivated in part by Jacobson's 1995 surprise result that the Einstein equations of gravity follow from the thermodynamic properties of event horizons. Taking a first tentative step in such a program, we derive the evaporation rate (or radiation spectrum) from black hole event horizons in a spacetime-free manner. Our result relies on a Hilbert space description of black hole evaporation, symmetries therein which follow from the inherent high dimensionality of black holes, global conservation of the no-hair quantities, and the existence of Penrose processes. Our analysis is not wedded to standard general relativity and so should apply to extended gravity theories where we find that the black hole area must be replaced by some other property in any generalized area theorem.

  17. Strong evaporation of a polyatomic gas

    Science.gov (United States)

    Cercignani, C.

    The problems arising in connection with the study of the structure of a jet evaporating into a vacuum are investigated. A kinetic theory description is given of the vapor motion into a vacuum for arbitrarily strong evaporation rates at an interphase boundary of circular shape. The solution of the problem is studied in three separate regions, in each of which the dependence of the solution on the space variables and the mean freepath is different. The theory that steady supersonic flows are impossible in a one-dimensional flow (Cercigani, 1980; Authur and Cercignani, 1980) is discussed. Finally, the analysis of the region near the wall is extended to a polyatomic gas, using the trimodal ansatz for the molecular distribution function of a monatomic gas. The main results of the analysis performed by Ytrehus for a monatomic gas (1975, 1977) are confirmed. New results concerning the discrepancy between internal and translational temperatures near the surface are presented.

  18. New insights into saline water evaporation from porous media: Complex interaction between evaporation rates, precipitation, and surface temperature

    Science.gov (United States)

    Shokri-Kuehni, Salomé M. S.; Vetter, Thomas; Webb, Colin; Shokri, Nima

    2017-06-01

    Understanding salt transport and deposition patterns during evaporation from porous media is important in many engineering and hydrological processes such as soil salinization, ecosystem functioning, and land-atmosphere interaction. As evaporation proceeds, salt concentration increases until it exceeds solubility limits, locally, and crystals precipitate. The interplay between transport processes, crystallization, and evaporation influences where crystallization occurs. During early stages, the precipitated salt creates an evolving porous structure affecting the evaporation kinetics. We conducted a comprehensive series of experiments to investigate how the salt concentration and precipitation influence evaporation dynamics. Our results illustrate the contribution of the evolving salt crust to the evaporative mass losses. High-resolution thermal imaging enabled us to investigate the complex temperature dynamics at the surface of precipitated salt, providing further confirmation of salt crust contribution to the evaporation. We identify different phases of saline water evaporation from porous media with the corresponding dominant mechanisms in each phase and extend the physical understanding of such processes.

  19. Modeling and simulation of direct contact evaporators

    OpenAIRE

    Campos F.B.; Lage P. L. C.

    2001-01-01

    A dynamic model of a direct contact evaporator was developed and coupled to a recently developed superheated bubble model. The latter model takes into account heat and mass transfer during the bubble formation and ascension stages and is able to predict gas holdup in nonisothermal systems. The results of the coupled model, which does not have any adjustable parameter, were compared with experimental data. The transient behavior of the liquid-phase temperature and the vaporization rate under q...

  20. A bubble column evaporator with basic flat-plate condenser for brackish and seawater desalination.

    Science.gov (United States)

    Schmack, Mario; Ho, Goen; Anda, Martin

    2016-01-01

    This paper describes the development and experimental evaluation of a novel bubble column-based humidification-dehumidification system, for small-scale desalination of saline groundwater or seawater in remote regions. A bubble evaporator prototype was built and matched with a simple flat-plate type condenser for concept assessment. Consistent bubble evaporation rates of between 80 and 88 ml per hour were demonstrated. Particular focus was on the performance of the simple condenser prototype, manufactured from rectangular polyvinylchlorid plastic pipe and copper sheet, a material with a high thermal conductivity that quickly allows for conduction of the heat energy. Under laboratory conditions, a long narrow condenser model of 1500 mm length and 100 mm width achieved condensate recovery rates of around 73%, without the need for external cooling. The condenser prototype was assessed under a range of different physical conditions, that is, external water cooling, partial insulation and aspects of air circulation, via implementing an internal honeycomb screen structure. Estimated by extrapolation, an up-scaled bubble desalination system with a 1 m2 condenser may produce around 19 l of distilled water per day. Sodium chloride salt removal was found to be highly effective with condensate salt concentrations between 70 and 135 µS. Based on findings and with the intent to reduce material cost of the system, a shorter condenser length of 750 mm for the non-cooled (passive) condenser and of 500 mm for the water-cooled condenser was considered to be equally efficient as the experimentally evaluated prototype of 1500 mm length.

  1. Elementary stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Tollestrup, A.V.; Dugan, G

    1983-12-01

    Major headings in this review include: proton sources; antiproton production; antiproton sources and Liouville, the role of the Debuncher; transverse stochastic cooling, time domain; the accumulator; frequency domain; pickups and kickers; Fokker-Planck equation; calculation of constants in the Fokker-Planck equation; and beam feedback. (GHT)

  2. Measure Guideline: Ventilation Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Springer, D. [Alliance for Residential Building Innovation (ARBI), David, CA (United States); Dakin, B. [Alliance for Residential Building Innovation (ARBI), David, CA (United States); German, A. [Alliance for Residential Building Innovation (ARBI), David, CA (United States)

    2012-04-01

    The purpose of this measure guideline is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  3. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  4. ELECTRON COOLING FOR RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI,I.

    2001-05-13

    The Accelerator Collider Department (CAD) at Brookhaven National Laboratory is operating the Relativistic Heavy Ion Collider (RHIC), which includes the dual-ring, 3.834 km circumference superconducting collider and the venerable AGS as the last part of the RHIC injection chain. CAD is planning on a luminosity upgrade of the machine under the designation RHIC II. One important component of the RHIC II upgrade is electron cooling of RHIC gold ion beams. For this purpose, BNL and the Budker Institute of Nuclear Physics in Novosibirsk entered into a collaboration aimed initially at the development of the electron cooling conceptual design, resolution of technical issues, and finally extend the collaboration towards the construction and commissioning of the cooler. Many of the results presented in this paper are derived from the Electron Cooling for RHIC Design Report [1], produced by the, BINP team within the framework of this collaboration. BNL is also collaborating with Fermi National Laboratory, Thomas Jefferson National Accelerator Facility and the University of Indiana on various aspects of electron cooling.

  5. An evaporation model of multicomponent solution drops

    Science.gov (United States)

    Sartori, Silvana; Liñán, Amable; Lasheras, Juan C.

    2010-11-01

    Solutions of polymers are widely used in the pharmaceutical industry as tablets coatings. These allow controlling the rate at which the drug is delivered, taste or appearance. The coating is performed by spraying and drying the tablets at moderate temperatures. The wetting of the coating solution on the pill's surface depends on the droplet Webber and Re numbers, angle of impact and on the rheological properties of the droplet. We present a model for the evaporation of multicomponent solutions droplets in a hot air environment with temperatures substantially lower than the boiling temperature of the solvent. As the liquid vaporizes from the surface the fluid in the drop increases in concentration, until reaching its saturation point. After saturation, precipitation occurs uniformly within the drop. As the surface regresses, a compacting front formed by the precipitate at its maximum packing density advances into the drop, while the solute continues precipitating uniformly. This porous shell grows fast due to the double effect of surface regression and precipitation. The evaporation rate is determined by the rates at which heat is transported to the droplet surface and at which liquid vapor diffuses away from it. When the drop is fully compacted, the evaporation is drastically reduced.

  6. An evaporation model of colloidal suspension droplets

    Science.gov (United States)

    Sartori, Silvana; Li\\ Nán, Amable; Lasheras, Juan C.

    2009-11-01

    Colloidal suspensions of polymers in water or other solvents are widely used in the pharmaceutical industry to coat tablets with different agents. These allow controlling the rate at which the drug is delivered, taste or physical appearance. The coating is performed by simultaneously spraying and drying the tablets with the colloidal suspension at moderately high temperatures. The spreading of the coating on the pills surface depends on the droplet Webber and Reynolds numbers, angle of impact, but more importantly on the rheological properties of the drop. We present a model for the evaporation of a colloidal suspension droplet in a hot air environment with temperatures substantially lower than the boiling temperature of the carrier fluid. As the liquid vaporizes from the surface, a compacting front advances into the droplet faster than the liquid surface regresses, forming a shell of a porous medium where the particles reach their maximum packing density. While the surface regresses, the evaporation rate is determined by both the rate at which heat is transported to the droplet surface and the rate at which liquid vapor is diffused away from it. This regime continues until the compacting front reaches the center of the droplet, at which point the evaporation rate is drastically reduced.

  7. Quantifying Evaporation in a Permeable Pavement System ...

    Science.gov (United States)

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. The U.S. Environmental Protection Agency (USEPA) constructed a 0.4-ha parking lot in Edison, NJ, that incorporated three different permeable pavement types in the parking lanes – permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). An impermeable liner installed 0.4 m below the driving surface in four 11.6-m by 4.74-m sections per each pavement type captures all infiltrating water and routes it to collection tanks that can contain events up to 38 mm. Each section has a design impervious area to permeable pavement area ratio of 0.66:1. Pressure transducers installed in the underdrain collection tanks measured water level for 24 months. Level was converted to volume using depth-to-volume ratios for individual collection tanks. Using a water balance approach, the measured infiltrate volume was compared to rainfall volume on an event-basis to determine the rainfall retained in the pavement strata and underlying aggregate. Evaporation since the previous event created additional storage in the pavement and aggregate layers. Events were divided into three groups based on antecedent dry period (ADP) and three, four-month categories of potential e

  8. SCC of stainless steel under evaporative conditions

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, H.; Arnvig, P.E.; Wasielewska, W.; Wegrelius, L.; Wolfe, C. [Avesta Sheffield AB, Avesta (Sweden)

    1998-12-31

    Three different test methods have been used to assess the susceptibility of different stainless steel grades to SCC under evaporative and immersed conditions. The methods employed were the drop evaporation test, the wick test and a high temperature, high pressure test simulating a feedwater heater tubing application in power plants. The alloys investigated were commercially produced austenitic and duplex stainless steels varying in chemical composition, plus one copper-nickel alloy. The resistance of austenitic stainless steels towards SCC increased by increasing the content of Ni, Mo and Cr, thus the super austenitic 654SMO{reg_sign} (uns32654) did not show any cracking in any of the three tests. The super austenitic 254SMO{reg_sign} (UNS31254) revealed only slight SCC in the simulated feed water heater tubing application while the equivalent N08367 revealed severe pitting and cracking. The drop evaporation test exhibited the most severe test conditions characterized by thermally induced fatigue effects, sensibility to onset of corrosion and severe acidic conditions generated under deposits on the test specimen. Some factors in stress corrosion cracking tests such as thermal fatigue, diffusion, heat transfer and stress condition, are discussed with regard to their influence on the test results.

  9. Spin coating of an evaporating polymer solution

    KAUST Repository

    Münch, Andreas

    2011-01-01

    We consider a mathematical model of spin coating of a single polymer blended in a solvent. The model describes the one-dimensional development of a thin layer of the mixture as the layer thins due to flow created by a balance of viscous forces and centrifugal forces and evaporation of the solvent. In the model both the diffusivity of the solvent in the polymer and the viscosity of the mixture are very rapidly varying functions of the solvent mass fraction. Guided by numerical solutions an asymptotic analysis reveals a number of different possible behaviours of the thinning layer dependent on the nondimensional parameters describing the system. The main practical interest is in controlling the appearance and development of a "skin" on the polymer where the solvent concentration reduces rapidly on the outer surface leaving the bulk of the layer still with high concentrations of solvent. In practice, a fast and uniform drying of the film is required. The critical parameters controlling this behaviour are found to be the ratio of the diffusion to advection time scales ε, the ratio of the evaporation to advection time scales δ and the ratio of the diffusivity of the pure polymer and the initial mixture exp(-1/γ). In particular, our analysis shows that for very small evaporation with δ

  10. Hundreds of fridges to cool the heart of ATLAS

    CERN Multimedia

    2006-01-01

    The detectors used in the LHC experiments are packed with electronics that will register thousands of particles produced in the collisions. All this hard work will generate a lot of heat, but there are systems in place to help the electronics to cool down, not shut down. Members of the DC section team in USA15 of the ATLAS cavern, standing behind four of the compressors used in the cooling system. The inlet and outlet pipes that carry the refrigerant to the experimental hall can be seen on the left. Left to right: M. Battistin, P. Bonneau, C. Houd, P. Feraudet, F. Corbaz, J. Lethinen, P. Guglielmini, M. Ciclet, P. Tropea, S. Berry (M. Pimenta absent).An unconfirmed member of the DC section :-) in charge of a part of the perfluoropropane distribution network for the ATLAS evaporative cooling system. The next time your desktop computer crashes from overheating, spare a thought for Pierre Feraudet, a member of the Detector Cooling section (TS/CV/DC). He is in charge of constructing the cooling systems for the d...

  11. Electron Cooling Study for MEIC

    Energy Technology Data Exchange (ETDEWEB)

    He, Zhang [Jefferson Lab., Newport News, VA (United States); Douglas, David R. [Jefferson Lab., Newport News, VA (United States); Derbenev, Yaroslav S. [Jefferson Lab., Newport News, VA (United States); Zhang, Yuhong [Jefferson Lab., Newport News, VA (United States)

    2015-09-01

    Electron cooling of the ion beams is one critical R&D to achieve high luminosities in JLab's MEIC proposal. In the present MEIC design, a multi-staged cooling scheme is adapted, which includes DC electron cooling in the booster ring and bunched beam electron cooling in the collider ring at both the injection energy and the collision energy. We explored the feasibility of using both magnetized and non-magnetized electron beam for cooling, and concluded that a magnetized electron beam is necessary. Electron cooling simulation results for the newly updated MEIC design is also presented.

  12. Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop

    Science.gov (United States)

    Tan, Huanshu; Diddens, Christian; Lv, Pengyu; Kuerten, J. G. M.; Zhang, Xuehua; Lohse, Detlef

    2016-11-01

    Evaporating liquid droplets are omnipresent in nature and technology, such as in inkjet printing, coating, deposition of materials, medical diagnostics, agriculture, the food industry, cosmetics, or spills of liquids. Here we show that the evaporation of such ternary mixtures can trigger a phase transition and the nucleation of microdroplets of one of the components of the mixture. As a model system, we pick a sessile Ouzo droplet (as known from daily life) and reveal and theoretically explain its four life phases: In phase I, the spherical cap-shaped droplet remains transparent while the more volatile ethanol is evaporating, preferentially at the rim of the drop because of the singularity there. This leads to a local ethanol concentration reduction and correspondingly to oil droplet nucleation there. This is the beginning of phase II, in which oil microdroplets quickly nucleate in the whole drop, leading to its milky color that typifies the so-called "Ouzo effect." Once all ethanol has evaporated, the drop, which now has a characteristic nonspherical cap shape, has become clear again, with a water drop sitting on an oil ring (phase III), finalizing the phase inversion. Finally, in phase IV, all water has evaporated, leaving behind a tiny spherical cap-shaped oil drop.

  13. Evaporation Kinetics of Polyol Droplets: Determination of Evaporation Coefficients and Diffusion Constants

    Science.gov (United States)

    Su, Yong-Yang; Marsh, Aleksandra; Haddrell, Allen E.; Li, Zhi-Ming; Reid, Jonathan P.

    2017-11-01

    In order to quantify the kinetics of mass transfer between the gas and condensed phases in aerosol, physicochemical properties of the gas and condensed phases and kinetic parameters (mass/thermal accommodation coefficients) are crucial for estimating mass fluxes over a wide size range from the free molecule to continuum regimes. In this study, we report measurements of the evaporation kinetics of droplets of 1-butanol, ethylene glycol (EG), diethylene glycol (DEG), and glycerol under well-controlled conditions (gas flow rates and temperature) using the previously developed cylindrical electrode electrodynamic balance technique. Measurements are compared with a model that captures the heat and mass transfer occurring at the evaporating droplet surface. The aim of these measurements is to clarify the discrepancy in the reported values of mass accommodation coefficient (αM, equals to evaporation coefficient based on microscopic reversibility) for 1-butanol, EG, and DEG and improve the accuracy of the value of the diffusion coefficient for glycerol in gaseous nitrogen. The uncertainties in the thermophysical and experimental parameters are carefully assessed, the literature values of the vapor pressures of these components are evaluated, and the plausible ranges of the evaporation coefficients for 1-butanol, EG, and DEG as well as uncertainty in diffusion coefficient for glycerol are reported. Results show that αM should be greater than 0.4, 0.2, and 0.4 for EG, DEG, and 1-butanol, respectively. The refined values are helpful for accurate prediction of the evaporation/condensation rates.

  14. Sorption cooling: a valid extension to passive cooling

    NARCIS (Netherlands)

    Doornink, D.J.; Burger, Johannes Faas; ter Brake, Hermanus J.M.

    2008-01-01

    Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for

  15. Comments on Ionization Cooling Channel Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States). Fermilab Center for Particle Astrophysics

    2013-12-04

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  16. Thermal design of two-stage evaporative cooler based on thermal comfort criterion

    Science.gov (United States)

    Gilani, Neda; Poshtiri, Amin Haghighi

    2017-04-01

    Performance of two-stage evaporative coolers at various outdoor air conditions was numerically studied, and its geometric and physical characteristics were obtained based on thermal comfort criteria. For this purpose, a mathematical model was developed based on conservation equations of mass, momentum and energy to determine heat and mass transfer characteristics of the system. The results showed that two-stage indirect/direct cooler can provide the thermal comfort condition when outdoor air temperature and relative humidity are located in the range of 34-54 °C and 10-60 %, respectively. Moreover, as relative humidity of the ambient air rises, two-stage evaporative cooler with the smaller direct and larger indirect cooler will be needed. In building with high cooling demand, thermal comfort may be achieved at a greater air change per hour number, and thus an expensive two-stage evaporative cooler with a higher electricity consumption would be required. Finally, a design guideline was proposed to determine the size of required plate heat exchangers at various operating conditions.

  17. Numerical study of heat and mass transfer during evaporation of a thin liquid film

    Directory of Open Access Journals (Sweden)

    Oubella M’hand

    2015-01-01

    Full Text Available A numerical study of mixed convection heat and mass transfer with film evaporation in a vertical channel is developed. The emphasis is focused on the effects of vaporization of three different liquid films having widely different properties, along the isothermal and wetted walls on the heat and mass transfer rates in the channel. The induced laminar downward flow is a mixture of blowing dry air and vapour of water, methanol or acetone, assumed as ideal gases. A two-dimensional steady state and elliptical flow model, connected with variable thermo-physical properties, is used and the phase change problem is based on thin liquid film assumptions. The governing equations of the model are solved by a finite volume method and the velocity-pressure fields are linked by SIMPLE algorithm. The numerical results, including the velocity, temperature and concentration profiles, as well as axial variations of Nusselt numbers, Sherwood number and dimensionless film evaporation rate are presented for two values of inlet temperature and Reynolds number. It was found that lower the inlet temperature and Re, the higher the induced flows cooling with respect of most volatile film. The better mass transfer rates related with film evaporation are found for a system with low mass diffusion coefficient.

  18. Irrigation Induced Surface Cooling in the Context of Modern and Increased Greenhouse Gas Forcing

    Science.gov (United States)

    Cook, Benjamin I.; Puma, Michael J.; Krakauer, Nir Y.

    2010-01-01

    There is evidence that expected warming trends from increased greenhouse gas (GHG) forcing have been locally masked by irrigation induced cooling, and it is uncertain how the magnitude of this irrigation masking effect will change in the future. Using an irrigation dataset integrated into a global general circulation model, we investigate the equilibrium magnitude of irrigation induced cooling under modern (Year 2000) and increased (A1B Scenario, Year 2050) GHG forcing, using modern irrigation rates in both scenarios. For the modern scenario, the cooling is largest over North America, India, the Middle East, and East Asia. Under increased GHG forcing, this cooling effect largely disappears over North America, remains relatively unchanged over India, and intensifies over parts of China and the Middle East. For North America, irrigation significantly increases precipitation under modern GHG forcing; this precipitation enhancement largely disappears under A1B forcing, reducing total latent heat fluxes and the overall irrigation cooling effect. Over India, irrigation rates are high enough to keep pace with increased evaporative demand from the increased GHG forcing and the magnitude of the cooling is maintained. Over China, GHG forcing reduces precipitation and shifts the region to a drier evaporative regime, leading to a relatively increased impact of additional water from irrigation on the surface energy balance. Irrigation enhances precipitation in the Middle East under increased GHG forcing, increasing total latent heat fluxes and enhancing the irrigation cooling effect. Ultimately, the extent to which irrigation will continue to compensate for the warming from increased GHG forcing will primarily depend on changes in the background evaporative regime, secondary irrigation effects (e.g. clouds, precipitation), and the ability of societies to maintain (or increase) current irrigation rates.

  19. Benefits of compressor inlet air cooling for gas turbine cogeneration plants

    Energy Technology Data Exchange (ETDEWEB)

    De Lucia, M.; Lanfranchi, C. [Univ. di Firenze (Italy). Dept. di Energetica; Boggio, V. [CRIT S.r.l., Prato (Italy)

    1996-07-01

    Compressor inlet air cooling is an effective method for enhancing the performance of gas turbine plants. This paper presents a comparative analysis of different solutions for cooling the compressor inlet air for the LM6000 gas turbine in a cogeneration plant operated in base load. Absorption and evaporative cooling systems are considered and their performance and economic benefits compared for the dry low-NO{sub x} LM6000 version. Reference is made to two sites in Northern and Southern Italy, whose climate data series for modeling the variations in ambient temperature during the single day were used to account for the effects of climate in the simulation. The results confirmed the advantages of inlet air cooling systems. In particular, evaporative cooling proved to be cost effective, though capable of supplying only moderate cooling, while absorption systems have a higher cost but are also more versatile and powerful in base-load operation. An integration of the two systems proved to be able to give both maximum performance enhancement and net economic benefit.

  20. Cooling Floor AC Systems

    Science.gov (United States)

    Jun, Lu; Hao, Ding; Hong, Zhang; Ce, Gao Dian

    The present HVAC equipments for the residential buildings in the Hot-summer-and-Cold-winter climate region are still at a high energy consuming level. So that the high efficiency HVAC system is an urgently need for achieving the preset government energy saving goal. With its advantage of highly sanitary, highly comfortable and uniform of temperature field, the hot-water resource floor radiation heating system has been widely accepted. This paper has put forward a new way in air-conditioning, which combines the fresh-air supply unit and such floor radiation system for the dehumidification and cooling in summer or heating in winter. By analyze its advantages and limitations, we found that this so called Cooling/ Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. We also recommend a methodology for the HVAC system designing, which will ensure the reduction of energy cost of users.

  1. AIR COOLED NEUTRONIC REACTOR

    Science.gov (United States)

    Fermi, E.; Szilard, L.

    1958-05-27

    A nuclear reactor of the air-cooled, graphite moderated type is described. The active core consists of a cubicle mass of graphite, approximately 25 feet in each dimension, having horizontal channels of square cross section extending between two of the opposite faces, a plurality of cylindrical uranium slugs disposed in end to end abutting relationship within said channels providing a space in the channels through which air may be circulated, and a cadmium control rod extending within a channel provided in the moderator. Suitable shielding is provlded around the core, as are also provided a fuel element loading and discharge means, and a means to circulate air through the coolant channels through the fuel charels to cool the reactor.

  2. Laser Cooling of Solids

    Science.gov (United States)

    2009-01-01

    Panel (b) com- pares the cooling efficiencies of available thermoelectric coolers ( TECs ) with ZBLANP:Yb3+-based optical refrigerators. Devices based...on materials with low parasitic heating will outperform TECs below 200 . Coolers made from current materials are less efficient than TECs at all...luminescence extraction efficiency are being explored as well. A novel method based on the frustrated total internal reflection across a vacuum “ nano -gap” is

  3. Non-Laser Cooling Techniques

    Science.gov (United States)

    Hilico, Laurent

    We first review trapped ion radiative cooling and show that it is only efficient for high frequency oscillating particles in Penning traps. We then describe in detail resistive cooling and explain in the frame of an exercice why and how thermal equilibrium with the resistor is reached. We finally discuss buffer gas cooling in Paul traps.

  4. Ice for air cooling

    Energy Technology Data Exchange (ETDEWEB)

    Voss, J.

    1987-04-09

    The first ice plant on an industrial scale came into service at Harmony goldmine in November 1985. This surface installation has a refrigeration output of about 5.2 MW, corresponding to 1000 t/d of ice. The ice melting tank is at a depth of 1088m. The planning and construction of this first industrial-scale ice plant were based on the result obtained from a research project which gave particular emphasis to investigating the problems related to the transport of ice in pipelines and to the ice-to-water heat transfer in ice-melting tanks. The particular advantage of ice as a coolant is that the mass circulation needed with ice is five times less than with water. It is claimed that, in the circumstances which are specific to Harmony mine, ice cooling is economically viable at a depth of only 1,100 m or thereabouts; however, calculations for very powerful cooling systems have shown that ice has a cost advantage over water + Pelton turbines only at depths of 3,000 m or more. Cost comparisons apart, this ice plant is useful for the testing of technology and safety in the production, transport and melting of the ice and prepares the way for a powerful ice cooling system which will work at great depths. 6 references.

  5. Low mass integrated cooling

    CERN Document Server

    Mapelli, Alessandro

    2014-01-01

    Low mass on - detec tor cooling systems are being developed and stud ied by the Detector Technology group (PH - DT) in the CERN Physics Department in close collaboration with LHC and non - LHC experiments . Two approaches are currently being investigated. The first approach, for barrel configurations, consists in integrating the cooli ng apparatus in light mechanical structures support ing the detectors. In this case , the thermal management can be achieved either with light cooling pipes and thin plates or with a network of microchannels embedded in thin strips of silicon or polyimide . Both configuratio ns are being investigated in the context of the 2018 upgrade program of the ALICE Inner Tracking System (ITS). Moreover, it is also possible to use a s ilicon microchannel cooling device itself as structural support for the detectors and electronics. Such a configur ation has been adopted by the NA62 collaboration for the ir GigaTracKer (GTK) as well as by the LHCb collaboration for the 2018 major upgrade of...

  6. Electron Cooling of RHIC

    CERN Document Server

    Ben-Zvi, Ilan; Barton, Donald; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Bruhwiler, David L; Burger, Al; Burov, Alexey; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Derbenev, Yaroslav S; Eidelman, Yury I; Favale, Anthony; Fedotov, Alexei V; Fischer, Wolfram; Funk, L W; Gassner, David M; Hahn, Harald; Harrison, Michael; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Koop, Ivan; Lambiase, Robert; Litvinenko, Vladimir N; MacKay, William W; Mahler, George; Malitsky, Nikolay; McIntyre, Gary; Meng, Wuzheng; Merminga, Lia; Meshkov, Igor; Mirabella, Kerry; Montag, Christoph; Nagaitsev, Sergei; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Parkhomchuk, Vasily; Parzen, George; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Sekutowicz, Jacek; Shatunov, Yuri; Sidorin, Anatoly O; Skrinsky, Aleksander Nikolayevich; Smirnov, Alexander V; Smith, Kevin T; Todd, Alan M M; Trbojevic, Dejan; Troubnikov, Grigory; Wang, Gang; Wei, Jie; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Zaltsman, Alex; Zhao, Yongxiang; ain, Animesh K

    2005-01-01

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.ags...

  7. Hollow-Fiber Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  8. Evaporation characteristics of ETBE-blended gasoline.

    Science.gov (United States)

    Okamoto, Katsuhiro; Hiramatsu, Muneyuki; Hino, Tomonori; Otake, Takuma; Okamoto, Takashi; Miyamoto, Hiroki; Honma, Masakatsu; Watanabe, Norimichi

    2015-04-28

    To reduce greenhouse gas emissions, which contribute to global warming, production of gasoline blended with ethyl tert-buthyl ether (ETBE) is increasing annually. The flash point of ETBE is higher than that of gasoline, and blending ETBE into gasoline will change the flash point and the vapor pressure. Therefore, it is expected that the fire hazard caused by ETBE-blended gasoline would differ from that caused by normal gasoline. The aim of this study was to acquire the knowledge required for estimating the fire hazard of ETBE-blended gasoline. Supposing that ETBE-blended gasoline was a two-component mixture of gasoline and ETBE, we developed a prediction model that describes the vapor pressure and flash point of ETBE-blended gasoline in an arbitrary ETBE blending ratio. We chose 8-component hydrocarbon mixture as a model gasoline, and defined the relation between molar mass of gasoline and mass loss fraction. We measured the changes in the vapor pressure and flash point of gasoline by blending ETBE and evaporation, and compared the predicted values with the measured values in order to verify the prediction model. The calculated values of vapor pressures and flash points corresponded well to the measured values. Thus, we confirmed that the change in the evaporation characteristics of ETBE-blended gasoline by evaporation could be predicted by the proposed model. Furthermore, the vapor pressure constants of ETBE-blended gasoline were obtained by the model, and then the distillation curves were developed. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Predicting Potential Evaporation in Topographically Complex Terrain

    Science.gov (United States)

    Koohafkan, M.; Thompson, S. E.; Hamilton, M. P.

    2012-12-01

    Predicting and understanding the water cycle in topographically complex terrain poses challenges for upscaling point-scale measurements of water and energy balance and for downscaling observations made from remote sensing or predictions made via global circulation models. This study evaluates hydrologic and climate data drawn from a spatially-distributed wireless sensor network at the Blue Oak Ranch Reserve near San Jose, California to investigate the influence of topographic variation, landscape position, and local ecology (vegetation) on one core component of the water balance: potential evaporation. High-resolution observations of solar radiation, ambient temperature, wind speed, and relative humidity are combined with canopy maps generated from LiDAR flyovers to develop spatially-distributed predictions of potential evaporation. These data are compared to estimates of EP based on inverse modeling of surface soil moisture data. Preliminary results suggest that the spatial structure of microclimate at Blue Oak Ranch Reserve is dominated by variations around the elevation gradient, with strong nocturnal inversions hypothesized to reflect the influence of the coastal marine layer. Estimates of EP based on the Penman-Monteith equation suggest that EP could vary by up to a factor of 5 across the site, with differences in vapor pressure deficit and canopy height largely responsible for this variability. The results suggest that a) large differences in the timing and magnitude of water stress could arise in topographically complex terrain due to localized differences in energy balance, and b) both localized and regional effects need to be accounted for when downscaling climate data over topographically complex sites. 2) Color map showing preliminary estimates of annual EP incorporating canopy information (spatially-distributed values of aerodynamic resistance and LAI) drawn from LiDAR imagery. The effect of the resistance on the dynamics is striking in its ability to

  10. Cooling the vertical surface by conditionally single pulses

    Directory of Open Access Journals (Sweden)

    Karpov Pavel

    2017-01-01

    Full Text Available You Sprays with periodic supply of the droplet phase have great opportunities to control the heat exchange processes. Varying pulse duration and frequency of their repetition, we can achieve the optimal conditions of evaporative cooling with minimization of the liquid flow rate. The paper presents experimental data on studying local heat transfer on a large subcooled surface, obtained on the original setup with multinozzle controlled system of impact irrigation by the gas-droplet flow. A contribution to intensification of the spray parameters (flow rate, pulse duration, repetition frequency per a growth of integral heat transfer was studied. Data on instantaneous distribution of the heat flux value helped us to describe the processes occurring on the studied surface. These data could describe the regime of “island” film cooling.

  11. Desiccant Dewpoint Cooling System Independent of External Water Sources

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Markussen, Wiebke B.

    2015-01-01

    This paper presents a patent pending technical solution aiming to make desiccant cooling systems independent of external water sources, hence solving problems of water availability, cost and treatment that can decrease the system attractiveness. The solution consists in condensing water from...... the air that regenerates the desiccant dehumidifier, and using it for running the evaporative coolers in the system. A closed regeneration circuit is used for maximizing the amount of condensed water. This solution is applied to a system with a desiccant wheel dehumidifier and a dew point cooler, termed...... desiccant dew-point cooling system, for demonstrating its function and applicability. Simulations are carried out for varying outdoor conditions under constant supply conditions. The results show that the system is independent of external water supply for the majority of simulated conditions. In comparison...

  12. Cooling the vertical surface by conditionally single pulses

    Science.gov (United States)

    Karpov, Pavel; Nazarov, Alexander; Serov, Anatoly; Terekhov, Victor

    2017-10-01

    You Sprays with periodic supply of the droplet phase have great opportunities to control the heat exchange processes. Varying pulse duration and frequency of their repetition, we can achieve the optimal conditions of evaporative cooling with minimization of the liquid flow rate. The paper presents experimental data on studying local heat transfer on a large subcooled surface, obtained on the original setup with multinozzle controlled system of impact irrigation by the gas-droplet flow. A contribution to intensification of the spray parameters (flow rate, pulse duration, repetition frequency) per a growth of integral heat transfer was studied. Data on instantaneous distribution of the heat flux value helped us to describe the processes occurring on the studied surface. These data could describe the regime of "island" film cooling.

  13. Light particle evaporation from dynamical systems

    Energy Technology Data Exchange (ETDEWEB)

    Aleshin, V.P.; Sidorenko, B. [Institute for Nuclear Research, Kiev (Ukraine); Centelles, M.; Vinas, X. [Departament d`Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, Barcelona (Spain)

    1997-01-01

    For the statistical particle-evaporation model to be applicable to particle emission from dynamical time-evolving systems, the system should closely follow the quasistatic path, which represents a sequence of conditional equilibrium shapes. We show that quasifission paths predicted by the one-body dissipation dynamics satisfy this requirement all the way from the contact point to the scission point, excluding short time intervals spent near the contact point (when neck fills in) and during separation (when waist develops). (author) 17 refs, 2 figs

  14. Cooling lubricants; Kuehlschmierstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, W. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Breuer, D. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Blome, H. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Deininger, C. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Hahn, J.U. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Kleine, H. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Nies, E. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Pflaumbaum, W. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Stockmann, R. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Willert, G. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Sonnenschein, G. [Maschinenbau- und Metall-Berufsgenossenschaft, Duesseldorf (Germany)

    1996-08-01

    As a rule, the base substances used are certain liquid hydrocarbons from mineral oils as well as from native and synthetic oils. Through the addition of further substances the cooling lubricant takes on the particular qualities required for the use in question. Employees working with cooling lubricants are exposed to various hazards. The assessment of the concentrations at the work station is carried out on the basis of existing technical rules for contact with hazardous substances. However, the application/implementation of compulsory investigation and supervision in accordance with these rules is made difficult by the fact that cooling lubricants are, as a rule, made up of complicated compound mixtures. In addition to protecting employees from exposure to mists and vapours from the cooling lubricants, protection for the skin is also of particular importance. Cooling lubricants should not, if at all possible, be brought into contact with the skin. Cleansing the skin and skin care is just as important as changing working clothes regularly, and hygiene and cleanliness at the workplace. Unavoidable emissions are to be immediately collected at the point where they arise or are released and safely disposed of. This means taking into account all sources of emissions. The programme presented in this report therefore gives a very detailed account of the individual protective measures and provides recommendations for the design of technical protection facilities. (orig./MG) [Deutsch] Als Basisstoffe dienen in der Regel bestimmte fluessige Kohlenwasserstoffverbindungen aus Mineraloelen sowie aus nativen oder synthetischen Oelen. Durch die Zugabe von weiteren Stoffen erlangt der Kuehlschmierstoff seine fuer den jeweiligen Anwendungsabfall geforderten Eigenschaften. Beschaeftigte, die mit Kuehlschmierstoffen umgehen, sind unterschiedliche Gefahren ausgesetzt. Die Beurteilung der Kuehlschmierstoffkonzentrationen in der Luft am Arbeitsplatz erfolgt auf der Grundlage bestehender

  15. Evaporation dynamics from wetted porous surfaces affected by internal drainage

    Science.gov (United States)

    Lehmann, Peter; Fuchs, Josefa; Dehaspe, Joni; Breitenstein, Daniel; Wunderli, Hans; Or, Dani

    2017-04-01

    Land surface evaporation dynamics following periodic rainfall events is complicated by liquid phase redistribution and concurrent internal drainage. The maintenance of constant and high evaporation rates (stage 1 evaporation) is predicated on water supply to the surface via continuous capillary pathways up to a characteristic depth defined by porous media properties. The objective is to extend the description to realistic conditions where evaporation and internal drainage occur concurrently. Column experiments have shown that evaporative losses were drastically reduced when drainage takes place. For initially high water content (and hydraulic conductivity) drainage dominates and shortens opportunity for stage 1 evaporation. A range of intermediate results emerges in which transition to stage 2 evaporation depends on initial conditions and soil properties. We derived a new definition of evaporative characteristic length that links soil hydraulic properties and initial conditions with predicted evaporative losses from wetted land surface. Experiments and theoretical considerations confirm the existence of an optimal water content defining conditions for maximal evaporative losses during stage 1.

  16. Laser cooling by adiabatic transfer

    Science.gov (United States)

    Norcia, Matthew; Cline, Julia; Bartolotta, John; Holland, Murray; Thompson, James

    2017-04-01

    We have demonstrated a new method of laser cooling applicable to particles with narrow linewidth optical transitions. This simple and robust cooling mechanism uses a frequency-swept laser to adiabatically transfer atoms between internal and motional states. The role of spontaneous emission is reduced (though is still critical) compared to Doppler cooling. This allows us to achieve greater slowing forces than would be possible with Doppler cooling, and may make this an appealing technique for cooling molecules. In this talk, I will present a demonstration of this technique in a cold strontium system. DARPA QUASAR, NIST, NSF PFC.

  17. Utilization of municipal wastewater for cooling in thermoelectric power plants

    Energy Technology Data Exchange (ETDEWEB)

    Safari, Iman [Illinois Inst. of Technology, Chicago, IL (United States); Walker, Michael E. [Illinois Inst. of Technology, Chicago, IL (United States); Hsieh, Ming-Kai [Carnegie Mellon Univ., Pittsburgh, PA (United States); Dzombak, David A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Liu, Wenshi [Univ. of Pittsburgh, PA (United States); Vidic, Radisav D. [Univ. of Pittsburgh, PA (United States); Miller, David C. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Abbasian, Javad [Illinois Inst. of Technology, Chicago, IL (United States)

    2013-09-01

    A process simulation model has been developed using Aspen Plus® with the OLI (OLI System, Inc.) water chemistry model to predict water quality in the recirculating cooling loop utilizing secondary- and tertiary-treated municipal wastewater as the source of makeup water. Simulation results were compared with pilot-scale experimental data on makeup water alkalinity, loop pH, and ammonia evaporation. The effects of various parameters including makeup water quality, salt formation, NH3 and CO2 evaporation mass transfer coefficients, heat load, and operating temperatures were investigated. The results indicate that, although the simulation model can capture the general trends in the loop pH, experimental data on the rates of salt precipitation in the system are needed for more accurate prediction of the loop pH. It was also found that stripping of ammonia and carbon dioxide in the cooling tower can influence the cooling loop pH significantly. The effects of the NH3 mass transfer coefficient on cooling loop pH appear to be more significant at lower values (e.g., kNH3 < 4×10-3 m/s) when the makeup water alkalinity is low (e.g., <90 mg/L as CaCO3). The effect of the CO2 mass transfer coefficient was found to be significant only at lower alkalinity values (e.g., kCO2<4×10-6 m/s).

  18. Preferential cooling of hot extremes from cropland albedo management.

    Science.gov (United States)

    Davin, Edouard L; Seneviratne, Sonia I; Ciais, Philippe; Olioso, Albert; Wang, Tao

    2014-07-08

    Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth's radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties.

  19. Laser Cooling of Molecular Anions

    CERN Document Server

    Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-01-01

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.

  20. Theoretical and computational analyses of LNG evaporator

    Science.gov (United States)

    Chidambaram, Palani Kumar; Jo, Yang Myung; Kim, Heuy Dong

    2017-04-01

    Theoretical and numerical analysis on the fluid flow and heat transfer inside a LNG evaporator is conducted in this work. Methane is used instead of LNG as the operating fluid. This is because; methane constitutes over 80% of natural gas. The analytical calculations are performed using simple mass and energy balance equations. The analytical calculations are made to assess the pressure and temperature variations in the steam tube. Multiphase numerical simulations are performed by solving the governing equations (basic flow equations of continuity, momentum and energy equations) in a portion of the evaporator domain consisting of a single steam pipe. The flow equations are solved along with equations of species transport. Multiphase modeling is incorporated using VOF method. Liquid methane is the primary phase. It vaporizes into the secondary phase gaseous methane. Steam is another secondary phase which flows through the heating coils. Turbulence is modeled by a two equation turbulence model. Both the theoretical and numerical predictions are seen to match well with each other. Further parametric studies are planned based on the current research.

  1. Influence of Oil on Refrigerant Evaporator Performance

    Science.gov (United States)

    Jong-Soo, Kim; Nagata, Katsuya; Katsuta, Masafumi; Tomosugi, Hiroyuki; Kikuchi, Kouichiro; Horichi, Toshiaki

    To explore the quantitative effect of the lubrication oil on the thermal and hydraulic evaporator performance, the detailed structure of two-phase refrigerant (R11) and lubrication oil (Suniso 5GS) flow has been investigated. Experiment has been performed using a transparent tube 20mm in inner diameter and 2600mm in total length as main test section, which was heated by surrounding hot water bath. This water bath also functioned as the visual observation section of the transition of two-phase flow pattern. Oil mass concentration was controlled initially, and circulated into the system. The void fraction at the main test section was measured by direct volume measurement using so-called "Quick Closing Valve" method. Since the effect of oil on the transition of two-phase flow pattern is emphasized at the low flow rate, operation was made at relatively low mass velocity, 50 and 100 kg/m2·s, five different oil concentrations were taken. Throughout the experiment, the evaporation pressure was kept at 105 kPa. In general, when contamination of the lubrication oil happened, the void fraction was decreasing due to the change of viscosity and surface tension and the occurence of the foaming. To correlate the void fraction as function of quality, Zivi's expression was modified to include the effect of oil concentration. The agreement between the data and this proposed correlation was favorable. Finally, to take into account the effect of lubrication oil, the new flow pattern diagram was proposed.

  2. Analytical solution for soil water redistribution during evaporation process.

    Science.gov (United States)

    Teng, Jidong; Yasufuku, Noriyuki; Liu, Qiang; Liu, Shiyu

    2013-01-01

    Simulating the dynamics of soil water content and modeling soil water evaporation are critical for many environmental and agricultural strategies. The present study aims to develop an analytical solution to simulate soil water redistribution during the evaporation process. This analytical solution was derived utilizing an exponential function to describe the relation of hydraulic conductivity and water content on pressure head. The solution was obtained based on the initial condition of saturation and an exponential function to model the change of surface water content. Also, the evaporation experiments were conducted under a climate control apparatus to validate the theoretical development. Comparisons between the proposed analytical solution and experimental result are presented from the aspects of soil water redistribution, evaporative rate and cumulative evaporation. Their good agreement indicates that this analytical solution provides a reliable way to investigate the interaction of evaporation and soil water profile.

  3. Keeping cool, staying virtuous

    DEFF Research Database (Denmark)

    Waltorp, Karen

    2015-01-01

    their everyday lives. I focus on love and marriage, the imperatives of appearing cool among peers, and keeping the family’s honour intact through the display of virtuous behaviour. Building on Bourdieu’s writings on the split habitus, I introduce the term composite habitus, as it underscores the aspect...... of a habitus that is split between (sometimes contradictory) composite parts. The composite habitus of the young women is more than a hysteresis effect (where disposition and field are in mismatch and the habitus misfires), as the composite habitus also opens up to a range of possible strategies. I present...

  4. Performance of Upgraded Cooling System for Lhd Helical Coils

    Science.gov (United States)

    Hamaguchi, S.; Imagawa, S.; Obana, T.; Yanagi, N.; Moriuchi, S.; Sekiguchi, H.; Oba, K.; Mito, T.; Motojima, O.; Okamura, T.; Semba, T.; Yoshinaga, S.; Wakisaka, H.

    2008-03-01

    Helical coils of the Large Helical Device (LHD) are large scale superconducting magnets for heliotron plasma experiments. The helical coils had been cooled by saturated helium at 4.4 K, 120 kPa until 2005. An upgrade of the cooling system was carried out in 2006 in order to improve the cryogenic stability of the helical coils and then it has been possible to supply the coils with subcooled helium at 3.2 K, 120 kPa. A designed mass flow of the supplied subcooled helium is 50 g/s. The subcooled helium is generated at a heat exchanger in a saturated helium bath. A series of two centrifugal cold compressors with gas foil bearing is utilized to lower the helium pressure in the bath. The supplied helium temperature is regulated by rotational speed of the cold compressors and power of a heater in the bath. The mass flow of the supplied helium is also controlled manually by a supply valve and its surplus is evaporated by ten heaters at the outlet above the coils. In the present study, the performance of the cooling system has been investigated and a stable operating method has also developed. As the result, it was confirmed that the performance of the upgraded cooling system satisfies the requirements.

  5. Development of techniques for cooling and trapping polar diatomic molecules

    Science.gov (United States)

    Glenn, David R.

    The study of ultracold dipolar molecules is an important emerging frontier in atomic physics. This thesis discusses the development of techniques for cooling diatomic molecules, focussing specifically on the idea of using a microwave frequency quasi-optical dipole trap for evaporative cooling. A prototype for such a trap has been designed, constructed, and tested. In order to load the microwave trap, a helium buffer gas cooled molecular beam source has been developed and characterized - in a variety of flow regimes, ranging from the effusive (thermal mean velocity, moderate flux), to the deeply hydrodynamic (large forward velocity, high-flux, high collimation). We explain the development of this source in detail. In particular, we describe recent work towards demonstrating direct laser cooling of a hydrodynamic SrF molecular beam. We have identified a set of quasi-closed transitions which should enable more than 104 photon scattering events, sufficient to decelerate a hydrodynamic beam to the Doppler limit. We present experimental results demonstrating optical deflection of a SrF beam by radiative force using this scheme, in which each molecule scatters on the order of 150 photons, limited by its interaction time with the lasers.

  6. Investigation of physical properties and stability of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems prepared by quench cooling, coprecipitation and ball milling

    DEFF Research Database (Denmark)

    Lim, Ai Wei; Löbmann, Korbinian; Grohganz, Holger

    2016-01-01

    OBJECTIVES: The objective was to characterize the structural behaviour of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems (1 : 1 molar ratio) prepared by quench cooling, co-evaporation and ball milling. METHODS: Powder X-ray diffraction (PXRD) and DSC were used to characterise...... by quench cooling (ln τ(β) = 2.4) and co-evaporation (ln τ(β) = 2.5). In contrast, molecular mobility of the naproxen-cimetidine samples followed the order co-evaporation (ln τ(β) = 0.8), quench cooling (ln τ(β) = 1.6) and ball milling (ln τ(β) = 1.8). CONCLUSION: The estimated relaxation times by the DSC...

  7. Dynamic Models of Vacuum-Evaporator Plants for Dairy Industry

    Directory of Open Access Journals (Sweden)

    G. M. Airapetiants

    2009-01-01

    Full Text Available The paper studies problems of linearized dynamic models intended for synthesis of automatic temperature control systems and vacuum depth in vacuum evaporators. А single-casing vacuum evaporator plant is considered as an object of automatic control. Disturbance input channels are discerned and transfer functions permitting to determine laws of temperature and vacuum regulation and optimum parameters for setting automatic regulators used for various operational modes of vacuum-evaporator plants are obtained on the basis of the executed analysis.

  8. Two phase flow instabilities in horizontal straight tube evaporator

    OpenAIRE

    2010-01-01

    Abstract It is essential to ensure the stability of a refrigeration system if the oscillation in evaporation process is the primary cause for the whole system instability. This paper is concerned with an experimental investigation of two phase flow instabilities in a horizontal straight tube evaporator of a refrigeration system. The relationship between pressure drop and mass flow with constant heat flux and evaporation pressure is measured and determined. It is found that there is...

  9. CFD analysis of tube-fin 'no-frost' evaporators

    OpenAIRE

    Barbosa, Jr,Jader R; Hermes,Christian J. L; Melo,Cláudio

    2010-01-01

    The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configuration. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The...

  10. Cooling performance of solar cell driven, thermoelectric cooling prototype headgear

    Energy Technology Data Exchange (ETDEWEB)

    Hara, T.; Azuma, H.; Shimizu, H.; Obora, H.; Sato, S. [Nippon Inst. of Technology, Saitama (Japan). Dept. of Systems Engineering

    1998-11-01

    Cooling performance of solar cell-driven, thermoelectric cooling prototype headgear was examined experimentally. Three types of prototype headgear were made and examined. They were cooled by thermoelectric elements and driven by solar cells. Conventional cooling caps driven by solar cells only blow ambient air to the face with an electric fan. A thermoelectric element was set at the front of the headgear to cool the forehead. Solar cells were mounted on the top and the brim of the headgear to work the thermoelectric element. Three prototypes of headgear with solar cells and a thermoelectric element were made and tested. Refrigeration capacity and thermal comfort were examined by subject in cases of sitting, walking and bicycling. The temperature difference between ambient and cooling temperature was required to be 4-5 degrees Celsius for thermal comfort. (author)

  11. Evaporation Of Hanford Waste Treatment Plant Direct Feed Low Activity Waste Effluent Management Facility Core Simulant

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Nash, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Mcclane, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-09-01

    stream, exacerbating their impact on the number of LAW glass containers that must be produced. Diverting the stream reduces the halides and sulfates in the recycled Condensate and is a key outcome of this work. This overall program examines the potential treatment and immobilization of this stream to enable alternative disposal. The objective of this task was to demonstrate evaporation of a simulant of the LAW Melter Off-gas Condensate expected during DFLAW operations, in order to predict the composition of the effluents from the EMF evaporator to aid in planning for their disposition. This document describes the results of that test using the core simulant. This simulant formulation is designated as the “core simulant”; other additives will be included for specific testing, such as volatiles for evaporation or hazardous metals for measuring leaching properties of waste forms. The results indicate that the simulant can easily be concentrated via evaporation. During that the pH adjustment step in simulant preparation, ammonium is quickly converted to ammonia, and most of the ammonia was stripped from the simulated waste and partitioned to the condensate. Additionally, it was found that after concentrating (>12x) and cooling that a small amount of LiF and Na3(SO4)F precipitate out of solution. With the exception of ammonia, analysis of the condensate indicated very low to below detectable levels of many of the constituents in the simulant, yielding very high decontamination factors (DF).

  12. Deep cooling of optically trapped atoms implemented by magnetic levitation without transverse confinement

    Science.gov (United States)

    Li, Chen; Zhou, Tianwei; Zhai, Yueyang; Xiang, Jinggang; Luan, Tian; Huang, Qi; Yang, Shifeng; Xiong, Wei; Chen, Xuzong

    2017-05-01

    We report a setup for the deep cooling of atoms in an optical trap. The deep cooling is implemented by eliminating the influence of gravity using specially constructed magnetic coils. Compared to the conventional method of generating a magnetic levitating force, the lower trap frequency achieved in our setup provides a lower limit of temperature and more freedoms to Bose gases with a simpler solution. A final temperature as low as ˜ 6 nK is achieved in the optical trap, and the atomic density is decreased by nearly two orders of magnitude during the second stage of evaporative cooling. This deep cooling of optically trapped atoms holds promise for many applications, such as atomic interferometers, atomic gyroscopes, and magnetometers, as well as many basic scientific research directions, such as quantum simulations and atom optics.

  13. Characteristics of Vacuum Freeze Drying with Utilization of Internal Cooling and Condenser Waste Heat for Sublimation

    Directory of Open Access Journals (Sweden)

    Muhammad Alhamid

    2013-09-01

    Full Text Available Vacuum freeze drying is an excellent drying method, but it is very energy-intensive because a relatively long drying time is required. This research investigates the utilization of condenser waste heat for sublimation as a way of accelerating the drying rate. In addition, it also investigates the effect of internal cooling combined with vacuum cooling in the pressure reduction process. Jelly fish tentacles were used as the specimen, with different configurations for condenser heat waste and internal cooling valve opening. The results show that heating with condenser heat waste can accelerate the drying rate up to 0.0035 kg/m2.s. In addition, pre-freezing by internal cooling prevents evaporation until the mass of the specimen is 0.47 g and promotes transition of the specimen into the solid phase.

  14. Distribution of Evaporating CO2 in Parallel Microchannels

    DEFF Research Database (Denmark)

    Brix, Wiebke; Elmegaard, Brian

    2008-01-01

    The impact on the heat exchanger performance due to maldistribution of evaporating CO2 in parallel channels is investigated numerically. A 1D steady state simulation model of a microchannel evaporator is built using correlations from the literature to calculate frictional pressure drop and heat...... to results obtained using R134a as refrigerant, and it is found that the performance of the evaporator using CO2 is less affected by the maldistribution than the evaporator using R134a as refrigerant. For both cases studied, the impact of the maldistribution was very small for CO2....

  15. Method for improving accuracy in full evaporation headspace analysis.

    Science.gov (United States)

    Xie, Wei-Qi; Chai, Xin-Sheng

    2017-05-01

    We report a new headspace analytical method in which multiple headspace extraction is incorporated with the full evaporation technique. The pressure uncertainty caused by the solid content change in the samples has a great impact to the measurement accuracy in the conventional full evaporation headspace analysis. The results (using ethanol solution as the model sample) showed that the present technique is effective to minimize such a problem. The proposed full evaporation multiple headspace extraction analysis technique is also automated and practical, and which could greatly broaden the applications of the full-evaporation-based headspace analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Passive-solar-cooling system concepts for small office buildings. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Whiddon, W.I.; Hart, G.K.

    1983-02-01

    This report summarizes the efforts of a small group of building design professionals and energy analysis experts to develop passive solar cooling concepts including first cost estimates for small office buildings. Two design teams were brought together at each of two workshops held in the fall of 1982. Each team included an architect, mechanical engineer, structural engineer, and energy analysis expert. This report presents the passive cooling system concepts resulting from the workshops. It summarizes the design problems, solutions and first-cost estimates relating to each technology considered, and documents the research needs identified by the participants in attempting to implement the various technologies in an actual building design. Each design problem presented at the workshops was based on the reference (base case) small office building analyzed as part of LBL's Cooling Assessment. Chapter II summarizes the thermal performance, physical specifications and estimated first-costs of the base case design developed for this work. Chapters III - VI describe the passive cooling system concepts developed for each technology: beam daylighting; mass with night ventilation; evaporative cooling; and integrated passive cooling systems. The final Chapters, VII and VIII present the preliminary implications for economics of passive cooling technologies (based on review of the design concepts) and recommendations of workshop participants for future research in passive cooling for commercial buildings. Appendices provide backup information on each chapter as indicated.

  17. Effects of Changes in Meteorological Conditions on Lake Evaporation, Water Temperature, and Heat Budget in a Deep Lake

    Science.gov (United States)

    Ito, Yuji; Momii, Kazuro

    To reveal effects of changes in meteorological conditions on lake evaporation, water temperature, and heat budget in a deep lake, sensitivity analyses have been performed for Lake Ikeda, Kagoshima prefecture. In the study, the sensitivities of three aspects to the 10%-increased solar radiation, air temperature, relative humidity, and wind speed were estimated based on numerical calculations for 1981-2005 with the verified one-dimensional mathematical model that computes thermal transfer in the lake. The results demonstrated that the meteorological component which gives the largest evaporation-promoting effect was solar radiation and the component which brings the largest lake-heating was air temperature. When solar radiation was increased, the vapor pressure difference between lake-surface and atmosphere was increased and the atmospheric stability was decreased, which present the desirable condition for evaporation. Air temperature being higher, the lake-surface was intensively heated by increased atmospheric radiation. As for the humidity case, lake evaporation was decreased in any season due to decrease in vapor pressure difference. Although rise in water temperature was caused by decrease in latent heat, it was inhibited with cooling by sensible heat. Wind being up, water temperature was fallen at the lake-surface and risen around the 20 m depth by vertical thermal mixing effect. The mixing effect prevented from releasing heat to atmosphere, resulting in the secondary large lake-heating but smaller than air temperature case.

  18. A Study of the Heat Transfer Coefficient of a Mini Channel Evaporator with R-134a as Refrigerant

    Science.gov (United States)

    Dollera, E. B.; Villanueva, E. P.

    2015-09-01

    The present study is to evaluate the heat transfer coefficient of the minichannel copper blocks used as evaporator with R-134a as the refrigerant. Experiments were conducted using three evaporator specimens of different channel hydraulic diameters (1.0mm, 2.0mm, 3.0mm). The total length for each channel is 640 mm. The dimension of each is 100mm.x50mm.x20mm. and the outside surfaces were machined to have fins. They were connected to a standard vapour compression refrigeration system. During each run of the experiment, the copper block evaporator was placed inside a small wind tunnel where controlled flow of air from a forced draft fan was introduced for the cooling process. The experimental set-up used data acquisition software and computer-aided simulation software was used to simulate the pressure drop and temperature profiles of the evaporator during the experimental run. The results were then compared with the Shah correlation. The Shah correlation over predicted and under predicted the values as compared with the experimental results for all of the three diameters and high variation for Dh=1.0mm. This indicates that the Shah correlation at small diameters is not the appropriate equation for predicting the heat transfer coefficient. The trend of the heat transfer coefficient is increasing as the size of the diameter increases.

  19. Cracks formation during blood drop evaporation

    Science.gov (United States)

    Sobac, Benjamin; Brutin, David; Université de Provence Team

    2011-03-01

    We firstly presented the pattern formation occurring when drops of whole blood desiccate in a recent publication. The phenomena presented evidence to involve lots of physical field such as surface chemistry, haematolology, fluid mechanics, heat transfer, colloids science... All these mechanisms are acting together and produce an axisymetric and reproducible pattern. Dried cellular components are segregated and deposited by a capillary flow. During the evaporation, the system is slowly drying and cracks when stresses are too important leading to the final pattern observed. In this presentation, we will present the mechanisms involved in the formation of crack patterns. The phenomenon presented here with red blood cells as the main colloids involved is very similar to the drying of drop of nanoparticules. We will explain the common point and the differences encountered.

  20. Polonium evaporation from dilute liquid metal solutions

    CERN Document Server

    Rizzi, Matthias; Eichler, Robert; Türler, Andreas; Mendonça, Tania Melo; Stora, Thierry; Gonzalez Prieto, Borja; Aerts, Alexander; Schumann, Dorothea

    2014-01-01

    The evaporation behavior of polonium as one of the most hazardous radionuclides produced in spallation based neutron sources with liquid lead-bismuth targets has been quantified in this study. The normalized apparent vapor pressure, i.e. the Henry constant of polonium over liquid lead-bismuth eutectic was determined in the temperature range relevant for operation of such targets, i.e. 164-500 degrees C. For comparison and better fundamental understanding, the Henry constant of polonium over pure liquid bismuth was determined in a temperature range of 300-500 degrees C. The Henry constants of polonium in this temperature range were found to be orders of magnitude higher than expected from earlier studies at higher temperatures. Possible mechanisms responsible for this unexpected behavior are discussed.

  1. Sessile droplet evaporation on superheated superhydrophobic surfaces

    CERN Document Server

    Hays, Robb C; Maynes, Daniel; Webb, Brent W

    2013-01-01

    This fluid dynamics video depicts the evaporation of sessile water droplets placed on heated superhydrophobic (SH) surfaces of varying cavity fraction, F_c, and surface temperature, T_s, above the saturation temperature, T_sat. Images were captured at 10,000 FPS and are played back at 30 FPS in this video. Teflon-coated silicon surfaces of F_c = 0, 0.5, 0.8, and 0.95 were used for these experiments. T_s ranging from 110{\\deg}C to 210{\\deg}C were studied. The video clips show how the boiling behavior of sessile droplets is altered with changes in surface microstructure. Quantitative results from heat transfer rate experiments conducted by the authors are briefly discussed near the end of the video.

  2. Modeling and simulation of direct contact evaporators

    Directory of Open Access Journals (Sweden)

    Campos F.B.

    2001-01-01

    Full Text Available A dynamic model of a direct contact evaporator was developed and coupled to a recently developed superheated bubble model. The latter model takes into account heat and mass transfer during the bubble formation and ascension stages and is able to predict gas holdup in nonisothermal systems. The results of the coupled model, which does not have any adjustable parameter, were compared with experimental data. The transient behavior of the liquid-phase temperature and the vaporization rate under quasi-steady-state conditions were in very good agreement with experimental data. The transient behavior of liquid height was only reasonably simulated. In order to explain this partial disagreement, some possible causes were analyzed.

  3. Vacuum drying plant for evaporator concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Benavides, E. [ENSA, Madrid (Spain)

    2001-07-01

    Volume reduction systems applied to evaporator concentrates in PWR and BWR save a significant amount of drums. The concentration to dry product is a technique that reaches the maximum volume reduction, compared to conventional techniques (cementation, polymerisation). Four Spanish N.P.P. (3 PWR and 1 BWR) have selected ENSA's process by means of fixed ''in drum vacuum drying system''. A 130-litre steel drum is used for drying without any additional requirement except vacuum resistance. This steel drum is introduced into a standard 200-litre drum. Five centimeters concrete shielding cylinder exists between both drums. Final package is classified as 19 GO according to ENRESA's acceptance code (dry waste with 5 cm concrete between 130-l and 200-l drum). The generation of cemented waste in five N.P.P. versus dried waste will be reduced 83%. This reduction will save a considerable amount in disposal costs. (authors)

  4. Capture of cenospheres by evaporating drops

    Science.gov (United States)

    Leong, K. H.; Ochs, Harry T.; Beard, K. V.

    The capture efficiency of evaporating cloud drops between 60 and 100 μm radius has been measured for 2 μm radius lithium carbonate hollow particles (cenospheres). Since the effective particle density is low compared to a 2-μm solid particle the cenospheres have reduced sedimentation speeds and a negligible inertial capture efficiency. The particles are sufficiently large ( Kn = 0.03) so that the phoretic theory in the slip regime ( Kn < 0.1) should apply. The measured capture efficiencies are significantly above the theoretical computations. There is some evidence to suggest that thermophoresis may be underestimated in the computations. This assessment is contigent on attributing the discrepancy between theory and experiment to the theoretical description of phoresis or its application to our experiment.

  5. Evaporation of urea at atmospheric pressure.

    Science.gov (United States)

    Bernhard, Andreas M; Czekaj, Izabela; Elsener, Martin; Wokaun, Alexander; Kröcher, Oliver

    2011-03-31

    Aqueous urea solution is widely used as reducing agent in the selective catalytic reduction of NO(x) (SCR). Because reports of urea vapor at atmospheric pressure are rare, gaseous urea is usually neglected in computational models used for designing SCR systems. In this study, urea evaporation was investigated under flow reactor conditions, and a Fourier transform infrared (FTIR) spectrum of gaseous urea was recorded at atmospheric pressure for the first time. The spectrum was compared to literature data under vacuum conditions and with theoretical spectra of monomolecular and dimeric urea in the gas phase calculated with the density functional theory (DFT) method. Comparison of the spectra indicates that urea vapor is in the monomolecular form at atmospheric pressure. The measured vapor pressure of urea agrees with the thermodynamic data obtained under vacuum reported in the literature. Our results indicate that considering gaseous urea will improve the computational modeling of urea SCR systems.

  6. An analysis of heat removal during cryogen spray cooling and effects of simultaneous airflow application.

    Science.gov (United States)

    Torres, J H; Tunnell, J W; Pikkula, B M; Anvari, B

    2001-01-01

    Cryogen spray cooling (CSC) is a method used to protect the epidermis from non-specific thermal injury that may occur as a result of various dermatological laser procedures. However, better understanding of cryogen deposition and skin thermal response to CSC is needed to optimize the technique. Temperature measurements and video imaging were carried out on an epoxy phantom as well as human skin during CSC with and without simultaneous application of airflow which was intended to accelerate cryogen evaporation from the substrate surface. An inverse thermal conduction model was used to estimate heat flux and total heat removed. Lifetime of the cryogen film deposited on the surface of skin and epoxy phantom lasted several hundred milliseconds beyond the spurt, but could be reduced to the spurt duration by application of airflow. Values over 100 J/cm(3) were estimated for volumetric heat removed from the epidermis using CSC. "Film cooling" instead of "evaporative cooling" appears to be the dominant mode of CSC on skin. Estimated values of heat removed from the epidermis suggest that a cryogen spurt as long as 200 milliseconds is required to counteract heat generated by high laser fluences (e.g., in treatment of port wine stains) in patients with high concentration of epidermal melanin. Additional cooling beyond spurt termination can be avoided by simultaneous application of airflow, although it is unclear at the moment if avoiding the additional cooling would be beneficial in the actual clinical situation. Copyright 2001 Wiley-Liss, Inc.

  7. INVESTIGATION OF THE PERFORMANCE OF AN ATMOSPHERIC COOLING TOWER USING FRESH AND SALTED WATER

    Directory of Open Access Journals (Sweden)

    A Haddad

    2012-01-01

    Full Text Available Cooling towers are extensively used to evacuate large quantities of heat at modest temperatures through a change of phase of the flowing cooling fluid. Based on this classical principle, the present study investigates the influence of salty water on the heat exchange produced. For that purpose, experiments are carried out using fresh and salty water. Furthermore, a comparison with the results produced through an approach involving the solution of energy equation involving the flow of air on an evaporating film of fluid. The detailed results show a preponderance of fresh water over the salty.

  8. Parametric analysis of a combined dew point evaporative-vapour compression based air conditioning system

    Directory of Open Access Journals (Sweden)

    Shailendra Singh Chauhan

    2016-09-01

    Full Text Available A dew point evaporative-vapour compression based combined air conditioning system for providing good human comfort conditions at a low cost has been proposed in this paper. The proposed system has been parametrically analysed for a wide range of ambient temperatures and specific humidity under some reasonable assumptions. The proposed system has also been compared from the conventional vapour compression air conditioner on the basis of cooling load on the cooling coil working on 100% fresh air assumption. The saving of cooling load on the coil was found to be maximum with a value of 60.93% at 46 °C and 6 g/kg specific humidity, while it was negative for very high humidity of ambient air, which indicates that proposed system is applicable for dry and moderate humid conditions but not for very humid conditions. The system is working well with an average net monthly power saving of 192.31 kW h for hot and dry conditions and 124.38 kW h for hot and moderate humid conditions. Therefore it could be a better alternative for dry and moderate humid climate with a payback period of 7.2 years.

  9. Natural convection with evaporation in a vertical cylindrical cavity under the effect of temperature-dependent surface tension

    Science.gov (United States)

    Kozhevnikov, Danil A.; Sheremet, Mikhail A.

    2018-01-01

    The effect of surface tension on laminar natural convection in a vertical cylindrical cavity filled with a weak evaporating liquid has been analyzed numerically. The cylindrical enclosure is insulated at the bottom, heated by a constant heat flux from the side, and cooled by a non-uniform evaporative heat flux from the top free surface having temperature-dependent surface tension. Governing equations with corresponding boundary conditions formulated in dimensionless stream function, vorticity, and temperature have been solved by finite difference method of the second-order accuracy. The influence of Rayleigh number, Marangoni number, and aspect ratio on the liquid flow and heat transfer has been studied. Obtained results have revealed that the heat transfer rate at free surface decreases with Marangoni number and increases with Rayleigh number, while the average temperature inside the cavity has an opposite behavior; namely, it growths with Marangoni number and reduces with Rayleigh number.

  10. Natural convection with evaporation in a vertical cylindrical cavity under the effect of temperature-dependent surface tension

    Science.gov (United States)

    Kozhevnikov, Danil A.; Sheremet, Mikhail A.

    2017-07-01

    The effect of surface tension on laminar natural convection in a vertical cylindrical cavity filled with a weak evaporating liquid has been analyzed numerically. The cylindrical enclosure is insulated at the bottom, heated by a constant heat flux from the side, and cooled by a non-uniform evaporative heat flux from the top free surface having temperature-dependent surface tension. Governing equations with corresponding boundary conditions formulated in dimensionless stream function, vorticity, and temperature have been solved by finite difference method of the second-order accuracy. The influence of Rayleigh number, Marangoni number, and aspect ratio on the liquid flow and heat transfer has been studied. Obtained results have revealed that the heat transfer rate at free surface decreases with Marangoni number and increases with Rayleigh number, while the average temperature inside the cavity has an opposite behavior; namely, it growths with Marangoni number and reduces with Rayleigh number.

  11. Direct cooled power electronics substrate

    Science.gov (United States)

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Lowe, Kirk T [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  12. Theory of tapered laser cooling

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Hiromi; Wei, J.

    1998-03-25

    A theory of tapered laser cooling for fast circulating ion beams in a storage ring is constructed. The authors describe the fundamentals of this new cooling scheme, emphasizing that it might be the most promising way to beam crystallization. The cooling rates are analytically evaluated to study the ideal operating condition. They discuss the physical implication of the tapering factor of cooling laser, and show how to determine its optimum value. Molecular dynamics method is employed to demonstrate the validity of the present theory.

  13. Experimental investigation and CFD analysis of a air cooled condenser heat pipe

    Directory of Open Access Journals (Sweden)

    Annamalai Selvan Arul

    2011-01-01

    Full Text Available In the present work a heat pipe of one meter length and 0.031m outer diameter was constructed and the experiments are conducted to determine the surface and vapour temperature at steady and transient conditions for two different input power in the evaporator section and cooling the condenser section by air. A CFD analysis was also carried and the results under steady state conditions are compared with the results obtained from the experiments and reported in this paper.

  14. Gas turbine performance enhancement via utilizing different integrated turbine inlet cooling techniques

    Directory of Open Access Journals (Sweden)

    Alaa A. El-Shazly

    2016-09-01

    Full Text Available Regions that experience ambient temperatures rising during hot seasons have significant losses and impacts on both output power and efficiency of the gas turbine. When the ambient temperature increases, the air mass flow rate decreases, and hence leads to reduce the gas turbine produced power. Ambient air can be cooled by using either evaporative cooler or absorption chiller. Currently, the performance was simulated thermodynamically for a natural gas operated gas turbine. The performance was tested for the base case without any turbine inlet cooling (TIC systems and compared with the performance for both evaporative cooler and absorption chiller separately in terms of output power, thermal efficiency, heat rate, specific fuel consumption, consumed fuel mass flow rate, and economics. Results showed that at air ambient temperature equals to 37 °C and after deducting all the associated auxiliaries power consumption for both evaporative cooler and absorption chiller, the absorption chiller with regenerator can achieve an augmentation of 25.47% in power and 33.66% in efficiency which provides a saving in average power price about 13%, while the evaporative cooler provides only an increase of 5.56% in power and 1.55% in efficiency, and a saving of 3% in average power price.

  15. Numerical study of the evaporation process and parameter estimation analysis of an evaporation experiment

    Directory of Open Access Journals (Sweden)

    K. Schneider-Zapp

    2010-05-01

    Full Text Available Evaporation is an important process in soil-atmosphere interaction. The determination of hydraulic properties is one of the crucial parts in the simulation of water transport in porous media. Schneider et al. (2006 developed a new evaporation method to improve the estimation of hydraulic properties in the dry range. In this study we used numerical simulations of the experiment to study the physical dynamics in more detail, to optimise the boundary conditions and to choose the optimal combination of measurements. The physical analysis exposed, in accordance to experimental findings in the literature, two different evaporation regimes: (i a soil-atmosphere boundary layer dominated regime (regime I close to saturation and (ii a hydraulically dominated regime (regime II. During this second regime a drying front (interface between unsaturated and dry zone with very steep gradients forms which penetrates deeper into the soil as time passes. The sensitivity analysis showed that the result is especially sensitive at the transition between the two regimes. By changing the boundary conditions it is possible to force the system to switch between the two regimes, e.g. from II back to I. Based on this findings a multistep experiment was developed. The response surfaces for all parameter combinations are flat and have a unique, localised minimum. Best parameter estimates are obtained if the evaporation flux and a potential measurement in 2 cm depth are used as target variables. Parameter estimation from simulated experiments with realistic measurement errors with a two-stage Monte-Carlo Levenberg-Marquardt procedure and manual rejection of obvious misfits lead to acceptable results for three different soil textures.

  16. ATLAS' major cooling project

    CERN Multimedia

    2005-01-01

    In 2005, a considerable effort has been put into commissioning the various units of ATLAS' complex cryogenic system. This is in preparation for the imminent cooling of some of the largest components of the detector in their final underground configuration. The liquid helium and nitrogen ATLAS refrigerators in USA 15. Cryogenics plays a vital role in operating massive detectors such as ATLAS. In many ways the liquefied argon, nitrogen and helium are the life-blood of the detector. ATLAS could not function without cryogens that will be constantly pumped via proximity systems to the superconducting magnets and subdetectors. In recent weeks compressors at the surface and underground refrigerators, dewars, pumps, linkages and all manner of other components related to the cryogenic system have been tested and commissioned. Fifty metres underground The helium and nitrogen refrigerators, installed inside the service cavern, are an important part of the ATLAS cryogenic system. Two independent helium refrigerators ...

  17. Magnetic entropy and cooling

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl; Kuhn, Luise Theil; Bahl, Christian Robert Haffenden

    2010-01-01

    Some manifestations of magnetism are well-known and utilized on an everyday basis, e.g. using a refrigerator magnet for hanging that important note on the refrigerator door. Others are, so far, more exotic, such as cooling by making use of the magnetocaloric eect. This eect can cause a change...... in the temperature of a magnetic material when a magnetic eld is applied or removed. For many years, experimentalists have made use of dilute paramagnetic materials to achieve milliKelvin temperatures by use of the magnetocaloric eect. Also, research is done on materials, which might be used for hydrogen, helium...... the eect: the isothermal magnetic entropy change and the adiabatic temperature change. Some of the manifestations and utilizations of the MCE will be touched upon in a general way and nally I will talk about the results I have obtained on a sample of Gadolinium Iron Garnet (GdIG, Gd3Fe5O12), which...

  18. Dry period cooling ameliorates physiological variables and blood acid base balance, improving milk production in murrah buffaloes

    Science.gov (United States)

    Aarif, Ovais; Aggarwal, Anjali

    2016-03-01

    This study aimed to evaluate the impact of evaporative cooling during late gestation on physiological responses, blood gas and acid base balance and subsequent milk production of Murrah buffaloes. To investigate this study sixteen healthy pregnant dry Murrah buffaloes (second to fourth parity) at sixty days prepartum were selected in the months of May to June and divided into two groups of eight animals each. One group of buffaloes (Cooled/CL) was managed under fan and mist cooling system during dry period. Group second buffaloes (Noncooled/NCL) remained as control without provision of cooling during dry period. The physiological responses viz. Rectal temperature (RT), Respiratory rate (RR) and Pulse rate were significantly ( P < 0.05) lower in group 2, with the provision of cooling. Skin surface temperature at thorax was significantly lower in cooled group relative to noncooled group. Blood pH and pO2 were significantly ( P < 0.05) higher in heat stressed group as compared to the cooled group. pCO2, TCO2, HCO3, SBC, base excess in extracellular fluid (BEecf), base excess in blood (BEb), PCV and Hb were significantly ( P < 0.05) higher in cooled group as compared to noncooled group. DMI was significantly ( P < 0.05) higher in cooled relative to noncooled animals. Milk yield, FCM, fat yield, lactose yield and total solid yield was significantly higher ( P < 0.05) in cooled group of Murrah buffaloes.

  19. Film cooling for a closed loop cooled airfoil

    Science.gov (United States)

    Burdgick, Steven Sebastian; Yu, Yufeng Phillip; Itzel, Gary Michael

    2003-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

  20. The Efficiency of Quartz Particles Evaporation in the Argon Plasma Flow of the RF Inductively Coupled Plasma Torch

    Directory of Open Access Journals (Sweden)

    Yu. M. Grishin

    2017-01-01

    injection into the plasma flow occurs in section at the distance of 5-25 mm before the inductor at a discharge current amplitude close to JCR 75-100 A.  Under aforementioned conditions the gas cooling RF ICPT with plasma power up to 10 kW provides evaporation of quartz particles with sizes up to 100-120 microns.

  1. America's Urban Forests: Keeping Our Cities Cool

    Science.gov (United States)

    Luvall, Jeffrey C.; Quattrochi, Dale A.

    1997-01-01

    The additional heating of the air over the city is the result of the replacement of naturally vegetated surfaces with those composed of asphalt, concrete, rooftops and other man-made materials. The temperatures of these artificial surfaces can be 20 to 40 C higher than vegetated surfaces. Materials such as asphalt store much of the sun's energy and remains hot long after sunset. This produces a dome of elevated air temperatures 5 to 8 C greater over the city, compared to the air temperatures over adjacent rural areas. This effect is called the "urban heat island". Tree canopies can reduce the urban heat island effect by dissipating the solar energy received by transpiring water from leaf surfaces which cools the air by taking "heat" from the air to evaporate the water and by shading surfaces like asphalt, roofs, and concrete parking lots which prevents initial heating and storage of heat. It is difficult to take enough temperature measurements over a large city area to characterize the surface temperature variability and quantify the temperature reduction effects of tree canopies. However, the use of remotely sensed thermal data from airborne scanners are ideal for the task. In a study funded by NASA, a series of flights over Huntsville AL were performed in September 1994 and over Atlanta in May 1997. In this article we will examine the techniques of analyzing remotely sensed data for measuring the effect of tree canopies in reducing the urban heat island effect.

  2. Increasing the Efficiency of Maple Sap Evaporators with Heat Exchangers

    Science.gov (United States)

    Lawrence D. Garrett; Howard Duchacek; Mariafranca Morselli; Frederick M. Laing; Neil K. Huyler; James W. Marvin

    1977-01-01

    A study of the engineering and economic effects of heat exchangers in conventional maple syrup evaporators indicated that: (1) Efficiency was increased by 15 to 17 percent with heat exchangers; (2) Syrup produced in evaporators with heat exchangers was similar to syrup produced in conventional systems in flavor and in chemical and physical composition; and (3) Heat...

  3. Impacts of Salinity on Soil Hydraulic Properties and Evaporation Fluxes

    Science.gov (United States)

    Fierro, V.; Cristi Matte, F.; Suarez, F. I.; Munoz, J. F.

    2014-12-01

    Saline soils are common in arid zones, where evaporation from shallow groundwater is generally the main component of the water balance. Thus, to correctly manage water resources in these zones, it is important to quantify the evaporation fluxes. Evaporation from saline soils is a complex process that couples the movement of salts, heat, liquid water and water vapor, and strongly depends on the soil water content. Precipitation/dissolution reactions can change the soil structure and alter flow paths, modifying evaporation fluxes. We utilized the HYDRUS-1D model to investigate the effects of salinity on soil hydraulic properties and evaporation fluxes. HYDRUS-1D simulates the transport of liquid water, water vapor, and heat, and can incorporate precipitation/dissolution reactions of the major ions. To run the model, we determined the water retention curve for a soil with different salinities; and we used meteorological forcing from an experimental site from the Atacama Desert. It was found that higher sodium adsorption ratios in the soil increase the soil water retention capacity. Also, it was found that evaporation fluxes increase salts concentration near the soil surface, changing the soil's water retention capacity in that zone. Finally, movement of salts causes differences in evaporation fluxes. It is thus necessary to incorporate salt precipitation/dissolution reactions and its effects on the water retention curve to correctly simulate evaporation in saline soils

  4. Modeling Coupled Evaporation and Seepage in Ventilated Cavities

    Energy Technology Data Exchange (ETDEWEB)

    T. Ghezzehei; R. Trautz; S. Finsterle; P. Cook; C. Ahlers

    2004-07-01

    Cavities excavated in unsaturated geological formations are important to activities such as nuclear waste disposal and mining. Such cavities provide a unique setting for simultaneous occurrence of seepage and evaporation. Previously, inverse numerical modeling of field liquid-release tests and associated seepage into cavities were used to provide seepage-related large-scale formation properties by ignoring the impact of evaporation. The applicability of such models was limited to the narrow range of ventilation conditions under which the models were calibrated. The objective of this study was to alleviate this limitation by incorporating evaporation into the seepage models. We modeled evaporation as an isothermal vapor diffusion process. The semi-physical model accounts for the relative humidity, temperature, and ventilation conditions of the cavities. The evaporation boundary layer thickness (BLT) over which diffusion occurs was estimated by calibration against free-water evaporation data collected inside the experimental cavities. The estimated values of BLT were 5 to 7 mm for the open underground drifts and 20 mm for niches closed off by bulkheads. Compared to previous models that neglected the effect of evaporation, this new approach showed significant improvement in capturing seepage fluctuations into open cavities of low relative humidity. At high relative-humidity values (greater than 85%), the effect of evaporation on seepage was very small.

  5. 7 CFR 58.937 - Physical requirements for evaporated milk.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Physical requirements for evaporated milk. 58.937... requirements for evaporated milk. (a) Flavor. The product shall possess a sweet, pleasing and desirable flavor... objectionable tastes and odors. (b) Body and texture. The product shall be of uniform consistency and appearance...

  6. Potential for natural evaporation as a reliable renewable energy resource.

    Science.gov (United States)

    Cavusoglu, Ahmet-Hamdi; Chen, Xi; Gentine, Pierre; Sahin, Ozgur

    2017-09-26

    About 50% of the solar energy absorbed at the Earth's surface drives evaporation, fueling the water cycle that affects various renewable energy resources, such as wind and hydropower. Recent advances demonstrate our nascent ability to convert evaporation energy into work, yet there is little understanding about the potential of this resource. Here we study the energy available from natural evaporation to predict the potential of this ubiquitous resource. We find that natural evaporation from open water surfaces could provide power densities comparable to current wind and solar technologies while cutting evaporative water losses by nearly half. We estimate up to 325 GW of power is potentially available in the United States. Strikingly, water's large heat capacity is sufficient to control power output by storing excess energy when demand is low, thus reducing intermittency and improving reliability. Our findings motivate the improvement of materials and devices that convert energy from evaporation.The evaporation of water represents an alternative source of renewable energy. Building on previous models of evaporation, Cavusoglu et al. show that the power available from this natural resource is comparable to wind and solar power, yet it does not suffer as much from varying weather conditions.

  7. Studies on tin oxide films prepared by electron beam evaporation ...

    Indian Academy of Sciences (India)

    Transparent conducting tin oxide thin films have been prepared by electron beam evaporation and spray pyrolysis methods. Structural, optical and electrical properties were studied under different preparation conditions like substrate temperature, solution flow rate and rate of deposition. Resistivity of undoped evaporated ...

  8. Water storage and evaporation as constituents of rainfall interception

    NARCIS (Netherlands)

    Klaassen, W; Bosveld, F; de Water, E

    1998-01-01

    Intercepted rainfall may be evaporated during or after the rain event. Intercepted rain is generally determined as the difference between rainfall measurements outside and inside the forest. Such measurements are often used to discriminate between water storage and evaporation during rain as well.

  9. Droplet Evaporator For High-Capacity Heat Transfer

    Science.gov (United States)

    Valenzuela, Javier A.

    1993-01-01

    Proposed heat-exchange scheme boosts heat transfer per unit area. Key component is generator that fires uniform size droplets of subcooled liquid at hot plate. On impact, droplets spread out and evaporate almost instantly, removing heat from plate. In practice, many generator nozzles arrayed over evaporator plate.

  10. 40 CFR 86.1243-96 - Calculations; evaporative emissions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Calculations; evaporative emissions... Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles § 86.1243-96 Calculations; evaporative... equations can be used in integral form. (i) Methanol emissions: ER06OC93.133 Where, (A) MCH 3 OH=methanol...

  11. 40 CFR 86.143-96 - Calculations; evaporative emissions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Calculations; evaporative emissions... Complete Heavy-Duty Vehicles; Test Procedures § 86.143-96 Calculations; evaporative emissions. (a) The... can be used in integral form. (i) Methanol emissions: MCH 3 OH=ρCH 3 OH Vmix× (CCH 3 OH, rl−CCH 3 OH...

  12. Nonlinear Superheat and Evaporation Temperature Control of a Refrigeration Plant

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Thybo, Claus; Larsen, Lars F. S.

    2006-01-01

    This paper proposes novel control of the superheat of the evaporator in a refrigeration system. A new model of the evaporator is developed and based on this model the superheat is transferred to a referred variable. It is shown that control of this variable leads to a linear system independent...

  13. A phylogenetic approach to total evaporative water loss in mammals.

    Science.gov (United States)

    Van Sant, Matthew J; Oufiero, Christopher E; Muñoz-Garcia, Agustí; Hammond, Kimberly A; Williams, Joseph B

    2012-01-01

    Maintaining appropriate water balance is a constant challenge for terrestrial mammals, and this problem can be exacerbated in desiccating environments. It has been proposed that natural selection has provided desert-dwelling mammals physiological mechanisms to reduce rates of total evaporative water loss. In this study, we evaluated the relationship between total evaporative water loss and body mass in mammals by using a recent phylogenetic hypothesis. We compared total evaporative water loss in 80 species of arid-zone mammals to that in 56 species that inhabit mesic regions, ranging in size from 4 g to 3,500 kg, to test the hypothesis that mammals from arid environments have lower rates of total evaporative water loss than mammals from mesic environments once phylogeny is taken into account. We found that arid species had lower rates of total evaporative water loss than mesic species when using a dichotomous variable to describe habitat (arid or mesic). We also found that total evaporative water loss was negatively correlated with the average maximum and minimum environmental temperature as well as the maximum vapor pressure deficit of the environment. Annual precipitation and the variable Q (a measure of habitat aridity) were positively correlated with total evaporative water loss. These results support the hypothesis that desert-dwelling mammals have lower rates of total evaporative water loss than mesic species after controlling for body mass and evolutionary relatedness regardless of whether categorical or continuous variables are used to describe habitat.

  14. Theoretical study on separate sensible and latent cooling air-conditioning system

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Jiazhen; Hwang, Yunho; Radermacher, Reinhard [Center for Environmental Energy Engineering, Department of Mechanical Engineering, University of Maryland, 3163 Glenn Martin Hall Bldg., College Park, MD 20742 (United States)

    2010-05-15

    The advantage of separating sensible and latent cooling (SSLC) via the use of separate cycles is saving energy by raising the evaporating temperature of the sensible cooling process. In this study, the pertinent characteristics of the SSLC system using two parallel vapor compression cycles were investigated. The requirement for high air flow rate through the sensible evaporator was the most important hardware design issue, since it might lead to a high air-side pressure drop. To address this issue, a new air distribution method, which could significantly reduce the pressure drop, was proposed to replace the conventional one. The heat exchanger modeling results demonstrated that sensible evaporators of the SSLC system could provide the equivalent cooling capacity at reduced air-side pressure drop to that of the conventional system without increasing the total heat transfer area. Although initial investment of the SSLC system is projected to be higher than the conventional system, the estimated operating cost of the SSLC system is lower than the conventional one because of the low energy consumption. (author)

  15. Operating characteristics of transcritical CO2 heat pump for simultaneous water cooling and heating

    Directory of Open Access Journals (Sweden)

    Sarkar Jahar

    2013-02-01

    Full Text Available The effects of water-side operating conditions (mass flow rates and inlet temperatures of both evaporator and gas cooler on the experimental as well as simulated performances (cooling and heating capacities, system coefficient of performance (COP and water outlet temperatures of the transcritical CO2 heat pump for simultaneous water cooling and heating the are studied and revised. Study shows that both the water mass flow rate and inlet temperature have significant effect on the system performances. Test results show that the effect of evaporator water mass flow rate on the system performances and water outlet temperatures is more pronounced (COP increases by 0.6 for 1 kg/min compared to that of gas cooler water mass flow rate (COP increases by 0.4 for 1 kg/min and the effect of gas cooler water inlet temperature is more significant (COP decreases by 0.48 for given range compared to that of evaporator water inlet temperature (COP increases by 0.43 for given range. Comparisons of experimental values with simulated results show the maximum deviation of 5% for cooling capacity, 10% for heating capacity and 16% for system COP.

  16. Analysis of a Solar Cooling System for Climatic Conditions of Five Different Cities of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    M. Mujahid Rafique

    2016-01-01

    Full Text Available Air high in humidity leads to uncomfortable conditions and promotes the growth of different fungi and bacteria, which may cause health problems. The control of moisture content in the air using traditional air conditioning techniques is not a suitable option due to large consumption of primary energy and hence emission of greenhouse gases. The evaporative cooling technology is a cost effective and eco-friendly alternative but can provide thermal comfort conditions only under low humidity conditions. However, the evaporative cooling method can be used effectively in conjunction with desiccant dehumidifiers for better control of humidity. Such systems can control the temperature and humidity of the air independently and can effectively utilize the low-grade thermal energy resources. In this paper, the theoretical analysis of desiccant based evaporative cooling systems is carried out for five cities in Saudi Arabia (Jeddah, Jazan, Riyadh, Hail, and Dhahran. It has been observed that the coefficient of performance (COP of the system varies from 0.275 to 0.476 for different locations. The water removal capacity of the desiccant wheel is at its maximum for the climatic conditions of Jazan and at its minimum for Hail. The effect of climatic conditions of five cities on regeneration temperature, air mass flow rate, and potential of solar energy has been evaluated using RET Screen software.

  17. Evaporation Dynamics of Moss and Bare Soil in Boreal Forests

    Science.gov (United States)

    Dempster, S.; Young, J. M.; Barron, C. G.; Bolton, W. R.

    2013-12-01

    Evaporation dynamics of mosses is a critical process in boreal and arctic systems and represents a key uncertainty in hydrology and climate models. At this point, moss evaporation is not well quantified at the plot or landscape scale. Relative to bare soil or litter evaporation, moss evaporation can be challenging to predict because the water flux is not isolated to the moss surface. Evaporation can originate from nearly 10 cm below the surface. Some mosses can wick moisture from even deeper than 10 cm, which subsequently evaporates. The goal of this study was to use field measurements to quantify the moss evaporation dynamics in a coniferous forest relative to bare ground or litter evaporation dynamics in a deciduous forest in Interior Alaska. Measurements were made in two ecosystem types within the boreal forest of Interior Alaska: a deciduous forest devoid of moss and a coniferous forest with a thick moss layer. A small clear chamber was attached to a LiCor 840 infrared gas analyzer in a closed loop system with a low flow rate. Water fluxes were measured for ~ 90 seconds on each plot in dry and wet soil and moss conditions. Additional measurements included: soil temperature, soil moisture, air temperature, barometric pressure, dew point, relative humidity, and wind speed. Thermal infrared images were also captured in congruence with water flux measurements to determine skin temperature. We found that the moss evaporation rate was over 100% greater than the soil evaporation rate (0.057 g/min vs. 0.024 g/min), and evaporation rates in both systems were most strongly driven by relative humidity and surface temperature. Surface temperature was lower at the birch site than the black spruce site because trees shade the surface beneath the birch. High fluxes associated with high water content were sustained for a longer period of time over the mosses compared to the bare soil. The thermal IR data showed that skin temperature lagged the evaporation flux, such that the

  18. Simulations of dynamic resistive evaporation in a vacuum

    Science.gov (United States)

    Kazanskiy, N. L.; Kolpakov, V. A.; Krichevskiy, S. V.; Podlipnov, V. V.

    2017-10-01

    The model of dynamic resistive evaporation in vacuum has been considered, and the model takes into account the structural peculiarities of the corresponding evaporator. In the model, the dependences to determine the time of material heating up to evaporation temperature as well as dynamic characteristics of the evaporation have been obtained. It has been shown that the obtained characteristics are nonharmonic and periodically repeated. The adequacy of the developed model to the physical model has been corroborated. It has been found that the discrepancy between the experimental and calculated time characteristics of shutter movement is not higher than 5%. The recommendations for using the suggested model to fabricate of thin films of multicomponent materials via thermal evaporation have been considered.

  19. Complex Effects of Salinity on Water Evaporation From Porous Media.

    Science.gov (United States)

    Shokri-Kuehni, S. M. S.; Webb, C.; Shokri, N.

    2016-12-01

    Saline water evaporation from porous media is influenced by transport properties of porous media, properties of the evaporating solution and external conditions. In this work, we investigated the effects of salt concentration on the drying behaviour of a porous medium and its surface temperature. Our key focus was about how the precipitated salt forming at the surface of drying porous media influences the evaporation rate. To do so, a series of evaporation experiments were conducted using columns packed with sand particles saturated with NaCl solutions of varying concentrations. The columns were placed on digital balances to record the evaporation dynamics and were exposed to metal halide lamps to boost the evaporation. A FLIR thermal camera was fixed above the sand columns to record the surface temperature. Additional experiments were conducted using sand packs saturated with salty water in the presence of water table at well-defined depths using Mariotte flasks. We could delineate the effects of salt concentration and crust formation on the general dynamics of the evaporation process (at different salt concentrations). Microscopic analysis of precipitated salt at the surface revealed the complex dynamics of salt evolution at the surface and its consequences on the evaporation behaviour. Our results suggest that the presence of porous salt at the surface causes top-supplied creeping of the solution feeding the growth of subsequent precipitation. This causes appearance and disappearance of cold-spots at the surface of porous media brought about by crust formation and preferential water evaporation visualized by the thermal images. This study extends the fundamental understanding of the evaporation of saline water from porous media.

  20. Newton's Law of Cooling Revisited

    Science.gov (United States)

    Vollmer, M.

    2009-01-01

    The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer…

  1. Be Cool, Man! / Jevgeni Levik

    Index Scriptorium Estoniae

    Levik, Jevgeni

    2005-01-01

    Järg 1995. aasta kriminaalkomöödiale "Tooge jupats" ("Get Shorty") : mängufilm "Be Cool, Chili Palmer on tagasi!" ("Be Cool") : režissöör F. Gary Gray, peaosades J. Travolta ja U. Thurman : USA 2005. Lisatud J. Travolta ja U. Thurmani lühiintervjuud

  2. Dialogues in the COOL Project

    NARCIS (Netherlands)

    Stalpers, S.I.P.; Kroeze, C.

    2013-01-01

    The Climate Options for the Long-term (COOL) Project is a participatory integrated assessment (PIA) comprising extensive dialogues at three levels: national, European and global. The objective of the COOL Project was to ‘develop strategic notions on how to achieve drastic reductions of greenhouse

  3. Jumping-droplet electronics hot-spot cooling

    Science.gov (United States)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

    2017-03-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  4. Production and sympathetic cooling of complex molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chaobo

    2008-06-24

    This thesis reports on experimental and theoretical studies of the sympathetic cooling of complex molecular ions demonstrating that this general method for cooling atomic and molecular ions is reliable and efficient. For this purpose, complex molecular ions and barium ions have been confined simultaneously in a linear Paul trap. The complex molecular ions are generated in an electrospray ionization system and transferred to the trap via a 2 m long octopole ion guide. These molecular ions are pre-cooled by room temperature helium buffer gas so that they can be captured by the trap. The atomic barium ions are loaded from a barium evaporator oven and are laser-cooled by a 493 nm cooling laser and a 650 nm repumping laser. Due to the mutual Coulomb interaction among these charged particles, the kinetic energy of the complex molecular ions can be reduced significantly. In our experiments we have demonstrated the sympathetic cooling of various molecules (CO{sub 2}, Alexa Fluor 350, glycyrrhetinic acid, cytochrome c) covering a wide mass range from a few tens to 13000 amu. In every case the molecular ions could be cooled down to millikelvin temperatures. Photo-chemical reactions of the {sup 138}Ba{sup +} ions in the ({sup 2}P{sub 1/2}) excited state with gases such as O{sub 2}, CO{sub 2}, or N{sub 2}O, could be observed. If the initial {sup 138}Ba{sup +} ion ensemble is cold, the produced {sup 138}BaO{sup +} ions are cold as well, with a similar temperature as the laser-cooled barium ions (a few tens of millikelvin). The back-reaction of {sup 138}BaO{sup +} ions with neutral CO to {sup 138}Ba{sup +} is possible and was observed in our experiments as well. A powerful molecular dynamics (MD) simulation program has been developed. With this program dynamic properties of ion ensembles, such as sympathetic interactions or heating effects, have been investigated and experimental results have been analyzed to obtain, for example, ion numbers and temperatures. Additionally, the

  5. Closed loop steam cooled airfoil

    Science.gov (United States)

    Widrig, Scott M.; Rudolph, Ronald J.; Wagner, Gregg P.

    2006-04-18

    An airfoil, a method of manufacturing an airfoil, and a system for cooling an airfoil is provided. The cooling system can be used with an airfoil located in the first stages of a combustion turbine within a combined cycle power generation plant and involves flowing closed loop steam through a pin array set within an airfoil. The airfoil can comprise a cavity having a cooling chamber bounded by an interior wall and an exterior wall so that steam can enter the cavity, pass through the pin array, and then return to the cavity to thereby cool the airfoil. The method of manufacturing an airfoil can include a type of lost wax investment casting process in which a pin array is cast into an airfoil to form a cooling chamber.

  6. Cooling Performance Characteristics on Mobile Air-Conditioning System for Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Ho-Seong Lee

    2013-01-01

    Full Text Available This study investigates the cooling performance characteristics of the mobile air-conditioning system using R744 (CO2 for the hybrid electric vehicle as an alternative to both the R-134a and the conventional air-conditioning system. The developed air-conditioning system is operated with an electric driven compressor in the battery driving mode and a belt driven compressor in the engine driving mode. The cooling performance characteristics of the developed system have been analyzed by experiments under various operating conditions of inlet air temperature, air flow rates for the gas cooler side and evaporator side, and electric compressor revolution respectively. As a result, cooling performances of the tested air-conditioning system for the EDC driving mode (electricity driven compressor were better than those for the BDC driving mode (belt driven compressor. The cooling capacity and cooling COP of the tested air-conditioning system for both driving modes were over 5.0 kW and 2.0, respectively. The observed cooling performance of the tested air-conditioning system may be sufficient for the cabin cooling of hybrid electric vehicles.

  7. Film cooling air pocket in a closed loop cooled airfoil

    Science.gov (United States)

    Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

    2002-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

  8. Indirect evaporative cooler using membrane-contained, liquid desiccant for dehumidification

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, Eric Joseph

    2016-12-13

    An indirect evaporative cooler for cooling inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air. The cooler includes a first flow channel for inlet supply air and a second flow channel adjacent the first for exhaust air. The first and second flow channels are defined in part by sheets of a membrane permeable to water vapor such that mass is transferred as a vapor through the membrane from the inlet supply air to a contained liquid desiccant for dehumidification and also to the exhaust air as heat is transferred from the inlet supply air to the liquid coolant. A separation wall divides the liquid desiccant and the coolant but allows heat to be transferred from the supply air to the coolant which releases water vapor to the counter or cross flowing exhaust air.

  9. 46 CFR 153.432 - Cooling systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cooling systems. 153.432 Section 153.432 Shipping COAST... Control Systems § 153.432 Cooling systems. (a) Each cargo cooling system must have an equivalent standby... cooling system. (b) Each tankship that has a cargo tank with a required cooling system must have a manual...

  10. Evaporative Gasoline Emissions and Asthma Symptoms

    Science.gov (United States)

    Gordian, Mary Ellen; Stewart, Alistair W; Morris, Stephen S

    2010-01-01

    Attached garages are known to be associated with indoor air volatile organic compounds (VOCs). This study looked at indoor exposure to VOCs presumably from evaporative emissions of gasoline. Alaskan gasoline contains 5% benzene making benzene a marker for gasoline exposure. A survey of randomly chosen houses with attached garages was done in Anchorage Alaska to determine the exposure and assess respiratory health. Householders were asked to complete a health survey for each person and a household survey. They monitored indoor air in their primary living space for benzene, toluene, ethylbenzene and xylenes for one week using passive organic vapor monitoring badges. Benzene levels in homes ranged from undetectable to 58 parts per billion. The median benzene level in 509 homes tested was 2.96 ppb. Elevated benzene levels in the home were strongly associated with small engines and gasoline stored in the garage. High concentrations of benzene in gasoline increase indoor air levels of benzene in residences with attached garages exposing people to benzene at levels above ATSDR’s minimal risk level. Residents reported more severe symptoms of asthma in the homes with high gasoline exposure (16%) where benzene levels exceeded the 9 ppb. PMID:20948946

  11. Central cooling: absorptive chillers

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1977-08-01

    This technology evaluation covers commercially available single-effect, lithium-bromide absorption chillers ranging in nominal cooling capacities of 3 to 1,660 tons and double-effect lithium-bromide chillers from 385 to 1,060 tons. The nominal COP measured at operating conditions of 12 psig input steam for the single-effect machine, 85/sup 0/ entering condenser water, and 44/sup 0/F exiting chilled-water, ranges from 0.6 to 0.65. The nominal COP for the double-effect machine varies from 1.0 to 1.15 with 144 psig entering steam. Data are provided to estimate absorption-chiller performance at off-nominal operating conditions. The part-load performance curves along with cost estimating functions help the system design engineer select absorption equipment for a particular application based on life-cycle costs. Several suggestions are offered which may be useful for interfacing an absorption chiller with the remaining Integrated Community Energy System. The ammonia-water absorption chillers are not considered to be readily available technology for ICES application; therefore, performance and cost data on them are not included in this evaluation.

  12. Ocular surface temperature in patients with evaporative and aqueous-deficient dry eyes: a thermographic approach.

    Science.gov (United States)

    Matteoli, S; Favuzza, E; Mazzantini, L; Aragona, P; Cappelli, S; Corvi, A; Mencucci, R

    2017-07-26

    In recent decades infrared thermography (IRT) has facilitated accurate quantitative measurements of the ocular surface temperature (OST), applying a non-invasive procedure. The objective of this work was to develop a procedure based on IRT, which allows characterizing of the cooling of the ocular surface of patients suffering from dry eye syndrome, and distinguishing among patients suffering from aqueous deficient dry eye (ADDE) and evaporative dry eyes (EDE). All patients examined (34 females and 4 males, 23-84 years) were divided into two groups according to their Schirmer I result (⩽ 7 mm for ADDE and  >  7 mm for EDE), and the OST was recorded for 7 s at 30 Hz. For each acquisition, the temperatures of the central cornea (CC) as well as those of both temporal and nasal canthi were investigated. Findings showed that the maximum temperature variation (up to 0.75  ±  0.29 °C) was at the CC for both groups. Furthermore, patients suffering from EDE tended to have a higher initial OST than those with ADDE, explained by the greater quantity of the tear film, evenly distributed over the entire ocular surface, keeping the OST higher initially. Results also showed that EDE patients had an average cooling rate higher than those suffering from ADDE, confirming the excessive evaporation of the tear film. Ocular thermography paves the way to become an effective tool for differentiating between the two different etiologies of dry eye syndrome.

  13. DEVELOPMENT OF A CHEST FREEZER – OPTIMUM DESIGN OF AN EVAPORATOR COIL

    Directory of Open Access Journals (Sweden)

    K. Kalyani Radha

    2012-06-01

    Full Text Available In a country such as India, food grains, fruit, vegetables, meat, poultry and fish, are very susceptible to microbial contamination and spoilage and require stringent preservation methods. One such method is by the use of a chest freezer for the storage of frozen food. This investigation considers different loads and design parameters for the development of a chest freezer using R134a as the working fluid. Experimental designs of an evaporator coil, condenser coil and capillary tube are investigated through the development of storage periods in terms of steady state and cyclic performance, by optimising the quantity of refrigerant charge, with strict adherence to the standards and requirement for maintaining an internal temperature of -23 °C at 43 °C ambient. Cyclic load performance tests optimise the performance of individual components selected for the design of a chest freezer. The system selection has a highly balanced performance with R134a and showed 118 kJ/kg cooling capacity with 8.42 coefficient of performance (COP. By the replacement of R134a, temperatures of -23 °C are maintained inside the freezer cabinet with low power consumption and an increase in the net refrigerating effect, which in turn increases the COP. The system design has optimum efficiency with moderate costs by optimising the length and diameter of the evaporator coil, i.e., 34.15 m and 7.94 mm, respectively.

  14. EVAPORATIVE DROPLETS IN ONE-COMPONENT FLUIDS DRIVEN BY THERMAL GRADIENTS ON SOLID SUBSTRATES

    KAUST Repository

    Xu, Xinpeng

    2013-03-20

    A continuum hydrodynamic model is presented for one-component liquid-gas flows on nonisothermal solid substrates. Numerical simulations are carried out for evaporative droplets moving on substrates with thermal gradients. For droplets in one-component fluids on heated/cooled substrates, the free liquid-gas interfaces are nearly isothermal. Consequently, a thermal singularity occurs at the contact line while the Marangoni effect due to interfacial temperature variation is suppressed. Through evaporation/condensation near the contact line, the thermal singularity makes the contact angle increase with the increasing substrate temperature. Due to this effect, droplets will move toward the cold end on substrates with thermal gradients. The droplet migration velocity is found to be proportional to the change of substrate temperature across the droplet. It follows that for two droplets of different sizes on a substrate with temperature gradient, the larger droplet moves faster and will catch up with the smaller droplet ahead. As soon as they touch, they coalesce rapidly into an even larger droplet that will move even faster. © 2013 World Scientific Publishing Company.

  15. DISTRIBUTION OF DISLOCATIONS IN AlN CRYSTALS GROWN ON EVAPORATING SiC SUBSTRATES

    Directory of Open Access Journals (Sweden)

    Tatiana S. Argunova

    2016-11-01

    Full Text Available By the use of high-resolution X-ray diffractometry and synchrotron radiation topography, the distribution of dislocations in AlN crystals grown on evaporating SiC substrates is studied. The growth of AlN layer in one process with the evaporation of SiC substrate gave the possibility to prevent the relaxation of thermal stresses through cracking of AlN during cooling the structure. The continuous 0.2-1.5 mm thick plates were used as the model objects for the study of dislocation structure near the AlN/SiC interface. Analysis of the broadening of the Bragg reflection peaks, the shape of scattering maps in reciprocal space and topographs showed that dislocations formed the mosaic structure, different from the distribution of threading dislocations in GaN epilayers. A theoretical model for misfit strain relaxation in the growing AlN layer is suggested. The results enable to clarify the dislocation processes during sublimation growth of industrial quality AlN crystals.

  16. Energy consumption during Refractance Window evaporation of selected berry juices

    Energy Technology Data Exchange (ETDEWEB)

    Nindo, C.I.; Tang, J. [Washington State University, Pullman, WA (United States). Dept. of Biological Systems Engineering; Powers, J.R. [Washington State University, Pullman, WA (United States). Dept. of Food Science and Human Nutrition; Bolland, K. [MCD Technologies, Tacoma, WA (United States)

    2004-07-01

    The Refractance Window evaporator represents a novel concept in the design of evaporation systems for small food processing plants. In this system thermal energy from circulating hot water is transmitted through a plastic sheet to evaporate water from a liquid product flowing concurrently on the top surface of the plastic. The objectives of this study were to investigate the heat transfer characteristics of this evaporator, determine its energy consumption, and capacity at different tilt angles and product flow rates. The system performance was evaluated with tap water, raspberry juice, and blueberry juice and puree as feed. With a direct steam injection heating method, the steam economy ranged from 0.64 to 0.84, while the overall heat transfer coefficient (U) was 666 W m{sup -2} {sup o}C{sup -1}. Under this condition, the highest evaporation capacity was 27.1 kg h{sup -1} m{sup -2} for blueberry juice and 31.8 kg h{sup -1} m{sup -2} for blueberry puree. The energy consumption was 2492-2719 kJ kg{sup -1} of water evaporated. Installation of a shell and tube heat exchanger with better temperature control minimized incidences of boiling and frequent discharge of condensate. The steam economy, highest evaporation rate and overall heat transfer coefficient increased to 0.99, 36.0 kg h{sup -1} m{sup -2} and 733 W m{sup -2} {sup o}C{sup -1}, respectively. [Author].

  17. High Performance Mars Liquid Cooling and Ventilation Garment Project

    Science.gov (United States)

    Terrier, Douglas; Clayton, Ronald; Whitlock, David; Conger, Bruce

    2015-01-01

    EVA space suit mobility in micro-gravity is enough of a challenge and in the gravity of Mars, improvements in mobility will enable the suited crew member to efficiently complete EVA objectives. The idea proposed is to improve thermal efficiencies of the liquid cooling and ventilation garment (LCVG) in the torso area in order to free up the arms and legs by removing the liquid tubes currently used in the ISS EVA suit in the limbs. By using shaped water tubes that greatly increase the contact area with the skin in the torso region of the body, the heat transfer efficiency can be increased to provide the entire liquid cooling requirement and increase mobility by freeing up the arms and legs. Additional potential benefits of this approach include reduced LCVG mass, enhanced evaporation cooling, increased comfort during Mars EVA tasks, and easing of the overly dry condition in the helmet associated with the Advanced Extravehicular Mobility Unit (EMU) ventilation loop currently under development.

  18. Transnasal cooling: a Pandora's box of transnasal patho-physiology.

    Science.gov (United States)

    Gupta, Deepak

    2011-08-01

    The innovative concept of transnasal evaporative cooling for therapeutic hypothermia in cardio-pulmonary-cerebro-resuscitation has therapeutic implications with evidence of rapid and selective brain cooling; however, this author wants to elicit that this concept may hold answers for many physiological phenomena which have not been explored or completely understood up till now. To affirm the physiological role of transnasal cooling, the innovative non-invasive brain temperature monitoring can help the investigators to explore and understand the following transnasal pathophysiological phenomena: (1) understanding correlation of brain temperature and sinus headache secondary to nasal blockade, (2) exploring the therapeutic role of nasal oxygen for prevention of delirium in intubated patients, (3) realizing the impact of controlled enclosed environments on the mood and affect of the inhabitants, (4) understanding the etio-pathogenesis of claustrophobia after excluding the confounding factors of morbid obesity, severe cardiopulmonary disease and incapacitating musculoskeletal diseases, (5) exploring the anthropological role of male pattern of moustache, beard and hair loss, and (6) possible development of a coolant moustache as proposed by the author. In summary, transnasal pathophysiology offers many promising lines of fruitful research to explore the non-olfactory physiological functions of nose in human beings. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Research on the evaporation of gasoline on beach sand

    Energy Technology Data Exchange (ETDEWEB)

    Berqueiro, J.R.; Dominguez, F.; Pons, J.M

    Gasoline evaporation is an importent factor in spill behavour. When a gasoline spill occurs on beach sand, part of the gasoline is spread over the sand surface while the rest is being absorbed. The spread and absorption rate depend on, amoung other things, the permeability of the sand which in turn also depends on it's water content. It is important to study the effects of gasoline evaporation on sand beaches in order to determine when risk of explosion is low, so that cleaning of the polluted beach surface can be carried out without danger. The effects of the evaporation of 90 and 97 octane (normal and super) gasoline on beach sand have been studied using the tray evaporation technique as described in the literature. The size of the sand particles have been included along with temperature and air speed as variables in the evaporation process. The effects of gasoline on the retention capacity of three distinct types of sand particles, as well as the effects of water in the sand, have been studied for normal and super gasolines. The following conclusions can be drawn: sand retention capacity is inversely proportional to sand particle size; when sand is moistened, its gasoline retention capacity increases proportionally with the decreasing particle size; with the same sand fractions and air speed conditions; the evaporation rate increases with increasing air speeds; with the same sand fractions and air speed conditions the evaporation rate increases with temperature; given the same temperature and air conditions, a gasoline spill on coarse sand evaporates faster than one on medium sand; and given the same temperatures and air speed conditions, the evaporation rate of normal gasoline spreading over any of the three types of sand is always higher than super gasoline due to the higher volatility of the 90 octane gasoline. 10 refs., 1 fig., 3 tabs.

  20. Evaluating the reliability of point estimates of wetland reference evaporation

    Directory of Open Access Journals (Sweden)

    H. Gavin

    2003-01-01

    Full Text Available The Penman-Monteith formulation of evaporation has been criticised for its reliance upon point estimates so that areal estimates of wetland evaporation based upon single weather stations may be misleading. Typically, wetlands comprise a complex mosaic of land cover types from each of which evaporative rates may differ. The need to account for wetland patches when monitoring hydrological fluxes has been noted. This paper presents work carried out over a wet grassland in Southern England. The significance of fetch on actual evaporation was examined using the approach adopted by Gash (1986 based upon surface roughness to estimate the fraction of evaporation sensed from a specified distance upwind of the monitoring station. This theoretical analysis (assuming near-neutral conditions reveals that the fraction of evaporation contributed by the surrounding area increases steadily to a value of 77% at a distance of 224 m and thereafter declines rapidly. Thus, point climate observations may not reflect surface conditions at greater distances. This result was tested through the deployment of four weather stations on the wetland. The resultant data suggested that homogeneous conditions prevailed so that the central weather station provided reliable areal estimates of reference evaporation during the observation period March–April 1999. This may be a result of not accounting for high wind speeds and roughness found in wetlands that lead to widespread atmospheric mixing. It should be noted this analysis was based upon data collected during the period March-April when wind direction was constant (westerly and the land surface was moist. There could be more variation at other times of the year that would lead to greater heterogeneity in actual evaporation. Keywords: evaporation, Penman-Monteith, automatic weather station, fetch, wetland