Comparative Effectiveness of Different Phase Change Materials to Improve Cooling Performance of Heat Sinks for Electronic Devices

Directory of Open Access Journals (Sweden)

Ahmad Hasan

2016-08-01

Full Text Available This paper thermo-physically characterizes salt hydrate, paraffin wax and milk fat as phase change materials (PCMs. The three PCMs are compared in terms of improving heat sink (HS performance for cooling electronic packaging. An experimental study is carried out on commercially available finned HS with and without PCM under natural ventilation (NV and forced ventilation (FV at different heat loads (4 W to 10 W. The results indicate that integration of all of the PCMs into the HS improves its cooling performance; however, milk fat lags behind the other two PCMs in terms of cooling produced. A three-dimensional pressure-based conjugate heat transfer model has been developed and validated with experimental results. The model predicts the parametric influence of PCM melting range, thermal conductivity and density on HS thermal management performance. The HS cooling performance improves with increased density and conductivity while it deteriorates with the wider melting range of the PCMs.

Cooling Performance of Additively Manufactured Microchannels and Film Cooling Holes

Science.gov (United States)

Stimpson, Curtis K.

Additive manufacturing (AM) enables fabrication of components that cannot be made with any other manufacturing method. Significant advances in metal-based AM systems have made this technology feasible for building production parts to be used use in commercial products. In particular, the gas turbine industry benefits from AM as a manufacturing technique especially for development of components subjected to high heat flux. It has been shown that the use of microchannels in high heat flux components can lead to more efficient cooling designs than those that presently exist. The current manufacturing methods have prevented the use of microchannels in such parts, but AM now makes them manufacturable. However, before such designs can become a reality, much research must be done to characterize impacts on flow and heat transfer of AM parts. The current study considers the effect on flow and heat transfer through turbine cooling features made with AM. Specifically, the performance of microchannels and film cooling holes made with laser powder bed fusion (L-PBF) is assessed. A number of test coupons containing microchannels were built from high temperature alloy powders on a commercially available L-PBF machine. Pressure drop and heat transfer experiments characterized the flow losses and convective heat transfer of air passing through the channels at various Reynolds numbers and Mach numbers. The roughness of the channels' surfaces was characterized in terms of statistical roughness parameters; the morphology of the roughness was examined qualitatively. Magnitude and morphology of surface roughness found on AM parts is unlike any form of roughness seen in the literature. It was found that the high levels of roughness on AM surfaces result in markedly augmented pressure loss and heat transfer at all Reynolds numbers, and conventional flow and heat transfer correlations produce erroneous estimates. The physical roughness measurements made in this study were correlated to

Theoretical analysis of the performance of different cooling strategies with the concept of cool exergy

DEFF Research Database (Denmark)

Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

2016-01-01

The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air for the v......The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air...... for the ventilation system being outdoor air vs. air from the crawl-space, and air-to-water heat pump vs. ground heat exchanger as cooling source) on system exergy performance were investigated. It is crucial to minimize the cooling demand because it is possible to use a wide range of heat sinks (ground, lake, sea......-water, etc.) and indoor terminal units, only with a minimized demand. The water-based floor cooling system performed better than the air-based cooling system; when an air-to-water heat pump was used as the cooling source, the required exergy input was 28% smaller for the floor cooling system. The auxiliary...

Thermal performance of a radiatively cooled system for quantum optomechanical experiments in space

International Nuclear Information System (INIS)

Pilan Zanoni, André; Burkhardt, Johannes; Johann, Ulrich; Aspelmeyer, Markus; Kaltenbaek, Rainer; Hechenblaikner, Gerald

2016-01-01

Highlights: • We improved performance and design aspects of a radiatively cooled instrument. • A heat-flow analysis showed near optimal performance of the shield design. • A simple modification to imaging optics allowed further improvements. • We studied the thermal behavior for different orbital cases. • A transfer-function analysis showed strong attenuation of thermal variations. - Abstract: Passive cooling of scientific instruments via thermal radiation to deep space offers many advantages over active cooling in terms of mission cost, lifetime and the achievable quality of vacuum and microgravity. Motivated by the mission proposal MAQRO to test the foundations of quantum physics harnessing a deep-space environment, we investigate the performance of a radiatively cooled instrument, where the environment of a test particle in a quantum superposition has to be cooled to less than 20 K. We perform a heat-transfer analysis between the instrument components and a transfer-function analysis on thermal oscillations induced by the spacecraft interior and dissipative sources. The thermal behavior of the instrument is discussed for an orbit around a Lagrangian point and for a highly elliptical Earth orbit. Finally, we investigate possible design improvements. These include a mirror-based design of the imaging system on the optical bench (OB) and an extension of the heat shields.

Improving performance and reducing costs of cooling towers

International Nuclear Information System (INIS)

Bartz, J.A.

1992-01-01

Cooling towers represent a significant capital investment at a steam electric power station. In addition, deficiencies in thermal performance can result in major operating penalties of fuel cost, replacement energy, and capacity addition. This paper summarizes two recent EPRI research projects aimed at reducing thermal performance deficiencies and decreasing installed costs of evaporative cooling towers. First, EPRI Research Project 2113, Cooling Tower Performance Prediction and Improvement, is summarized. This project has resulted in published data sets on the measured thermal performance characteristics of a variety of cooling tower packings, computer codes to predict tower performance, and computer code validation through large-scale tower performance measurements. Principal results are contained in an EPRIGEMS software module, Cooling Tower Advisor. This PC- based software contains a tutorial plus codes to predict tower thermal performance, arranged in a user-friendly format. The second EPRI effort, Research Project 2819-10/11, Fabric Structures for Power Plant Applications, has resulted in designs and costs of large structures with shells constructed of recently-developed fabrics. Primary power plant applications for such structures are the shells of natural draft cooling towers and coal-pile covers. Fabric structures offer low initial cost, acceptable life, and seismic superiority, among other advantages. Detailed conceptual designs and installed cost data are reviewed. 8 refs., 9 figs., 3 tabs

Cooling Performance Analysis of ThePrimary Cooling System ReactorTRIGA-2000Bandung

Science.gov (United States)

Irianto, I. D.; Dibyo, S.; Bakhri, S.; Sunaryo, G. R.

2018-02-01

The conversion of reactor fuel type will affect the heat transfer process resulting from the reactor core to the cooling system. This conversion resulted in changes to the cooling system performance and parameters of operation and design of key components of the reactor coolant system, especially the primary cooling system. The calculation of the operating parameters of the primary cooling system of the reactor TRIGA 2000 Bandung is done using ChemCad Package 6.1.4. The calculation of the operating parameters of the cooling system is based on mass and energy balance in each coolant flow path and unit components. Output calculation is the temperature, pressure and flow rate of the coolant used in the cooling process. The results of a simulation of the performance of the primary cooling system indicate that if the primary cooling system operates with a single pump or coolant mass flow rate of 60 kg/s, it will obtain the reactor inlet and outlet temperature respectively 32.2 °C and 40.2 °C. But if it operates with two pumps with a capacity of 75% or coolant mass flow rate of 90 kg/s, the obtained reactor inlet, and outlet temperature respectively 32.9 °C and 38.2 °C. Both models are qualified as a primary coolant for the primary coolant temperature is still below the permitted limit is 49.0 °C.

Evaluation of heat exchange performance for the auxiliary component cooling water system cooling tower in HTTR

International Nuclear Information System (INIS)

Tochio, Daisuke; Kameyama, Yasuhiko; Shimizu, Atsushi; Inoi, Hiroyuki; Yamazaki, Kazunori; Shimizu, Yasunori; Aragaki, Etsushi; Ota, Yukimaru; Fujimoto, Nozomu

2006-09-01

The auxiliary component cooling water system (ACCWS) is one of the cooling system in High Temperature Engineering Test Reactor (HTTR). The ACCWS has main two features, many facilities cooling, and heat sink of the vessel cooling system which is one of the engineering safety features. Therefore, the ACCWS is required to satisfy the design criteria of heat removal performance. In this report, heat exchange performance data of the rise-to-power-up test and the in-service operation for the ACCWS cooling tower was evaluated. Moreover, the evaluated values were compared with the design values, and it is confirmed that ACCWS cooling tower has the required heat exchange performance in the design. (author)

Improvement of Emergency Cooldown Tank in terms of long-term cooling

International Nuclear Information System (INIS)

Moon, Joo Hyung; Kim, Youngin; Kim, Keung Koo

2014-01-01

SMART received its Standard Design Approval(SDA) from Korea Government in 2012. After Fukushima accident, passively cooling system of nuclear reactor gets great attention and a consentience reached that at least 72 hours of grace time after an accident should be secured, during which a nuclear reactor remains in safe condition without any operator's intervention. To meet this requirement, SMART adapted passive cooling system such as passive residual heat removal system(PRHRS). It is composed of an emergency cooldown tank(ETC), a heat exchanger and a makeup tank. The ETC should be refilled periodically by auxiliary water supply system in order to use it beyond 72 hours. Otherwise the immersed heat exchanger would be exposed to the air, which would damage the function of PRHRS. To overcome this shortcoming, installation of an air-cooling heat exchanger at the top of the ETC is proposed as shown in Fig. 2. Here the top of the ETC is now closed. Evaporated steam is collected through the vertical duct and condensed through air-cooling heat exchanger. By natural circulation, water level of ETC can be maintained at steady state for a very long-term period. The purpose of the present study is to investigate the thermal sizing of air-cooling heat exchanger which extends the cooling period of ETC. Thermal sizing of air-cooling heat exchanger had been investigated by using several heat transfer correlations for natural convection of vertical tubes. Quantitative comparisons were made to find out how many tubes are required to remove the residual heat. This work would contribute to improve the current design of ETC and to extend the cooling period much longer than 72 hours, which will promote the passive safety function of SMART

Performance Evaluation of a Mechanical Draft Cross Flow Cooling Towers Employed in a Subtropical Region

Science.gov (United States)

Muthukumar, Palanisamy; Naik, Bukke Kiran; Goswami, Amarendra

2018-02-01

Mechanical draft cross flow cooling towers are generally used in a large-scale water cooled condenser based air-conditioning plants for removing heat from warm water which comes out from the condensing unit. During this process considerable amount of water in the form of drift (droplets) and evaporation is carried away along with the circulated air. In this paper, the performance evaluation of a standard cross flow induced draft cooling tower in terms of water loss, range, approach and cooling tower efficiency are presented. Extensive experimental studies have been carried out in three cooling towers employed in a water cooled condenser based 1200 TR A/C plant over a period of time. Daily variation of average water loss and cooling tower performance parameters have been reported for some selected days. The reported average water loss from three cooling towers is 4080 l/h and the estimated average water loss per TR per h is about 3.1 l at an average relative humidity (RH) of 83%. The water loss during peak hours (2 pm) is about 3.4 l/h-TR corresponding to 88% of RH and the corresponding efficiency of cooling towers varied between 25% and 45%.

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.

Performance comparison between a solar driven rotary desiccant cooling system and conventional vapor compression system (performance study of desiccant cooling)

International Nuclear Information System (INIS)

Ge, T.S.; Ziegler, F.; Wang, R.Z.; Wang, H.

2010-01-01

Solar driven rotary desiccant cooling systems have been widely recognized as alternatives to conventional vapor compression systems for their merits of energy-saving and being eco-friendly. In the previous paper, the basic performance features of desiccant wheel have been discussed. In this paper, a solar driven two-stage rotary desiccant cooling system and a vapor compression system are simulated to provide cooling for one floor in a commercial office building in two cities with different climates: Berlin and Shanghai. The model developed in the previous paper is adopted to predict the performance of the desiccant wheel. The objectives of this paper are to evaluate and compare the thermodynamic and economic performance of the two systems and to obtain useful data for practical application. Results show that the desiccant cooling system is able to meet the cooling demand and provide comfortable supply air in both of the two regions. The required regeneration temperatures are 55 deg. C in Berlin and 85 deg. C in Shanghai. As compared to the vapor compression system, the desiccant cooling system has better supply air quality and consumes less electricity. The results of the economic analysis demonstrate that the dynamic investment payback periods are 4.7 years in Berlin and 7.2 years in Shanghai.

Thermodynamic assessment of impact of inlet air cooling techniques on gas turbine and combined cycle performance

International Nuclear Information System (INIS)

Mohapatra, Alok Ku; Sanjay

2014-01-01

The article is focused on the comparison of impact of two different methods of inlet air cooling (vapor compression and vapor absorption cooling) integrated to a cooled gas turbine based combined cycle plant. Air-film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor pressure ratio, compressor inlet temperature (T i , C ), turbine inlet temperature (T i , T ), ambient relative humidity and ambient temperature on performance parameters of plant has been carried out. Optimum T i , T corresponding to maximum plant efficiency of combined cycle increases by 100 °C due to the integration of inlet air cooling. It has been observed that vapor compression cooling improves the efficiency of gas turbine cycle by 4.88% and work output by 14.77%. In case of vapor absorption cooling an improvement of 17.2% in gas cycle work output and 9.47% in gas cycle efficiency has been observed. For combined cycle configuration, however, vapor compression cooling should be preferred over absorption cooling in terms of higher plant performance. The optimum value of compressor inlet temperature has been observed to be 20 °C for the chosen set of conditions for both the inlet air cooling schemes. - Highlights: • Inlet air cooling improves performance of cooled gas turbine based combined cycle. • Vapor compression inlet air cooling is superior to vapor absorption inlet cooling. • For every turbine inlet temperature, there exists an optimum pressure ratio. • The optimum compressor inlet temperature is found to be 293 K

Evaluation of post-LOCA long term cooling performance in Korean standard nuclear power plants

International Nuclear Information System (INIS)

Bang, Young Seok; Jung, Jae Won; Seul, Kwang Won; Kim, Hho Jung

2001-01-01

The post-LOCA long term cooling (LTC) performance of the Korean Standard Nuclear Power Plant (KSNPP) is analyzed for both small break loss-of-coolant accidents (LOCA) and large break LOCA at cold leg. The RELAP5/MOD3.2.2 beta code is used to calculate the LTC sequences based on the LTC plan of the Korean Standard Nuclear Power Plants (KSNPP). A standard input model is developed such that LOCA and the followed LTC sequence can be calculated in a single run for both small break LOCA and large break LOCA. A spectrum of small break LOCA ranging from 0.02 to 0.5 ft 2 of break area and a double-ended guillotine break are analyzed. Through the code calculations, the thermal-hydraulic behavior and the boron behavior are evaluated and the effect of the important action including the safety injection tank (SIT) isolation and the simultaneous injection in LTC procedure is investigated. As a result, it is found that the sufficient margin is available in avoiding the boron precipitation in the core. It is also found that a further specific condition for the SIT isolation action need to be setup and it is recommended that the early initiation of the simultaneous injection be taken for larger break LTC sequences. (author)

Performance characteristics of a shower cooling tower

International Nuclear Information System (INIS)

Qi Xiaoni; Liu Zhenyan; Li Dandan

2007-01-01

This study was prompted by the need to design towers for applications in which, due to salt deposition on the packing and subsequent blockage, the use of tower packing is not practical. In contrast to conventional cooling towers, the cooling tower analyzed in this study is void of fill. By means of efficient atomization nozzles, a shower cooling tower (SCT) is possible to be applied in industry, which, in terms of water cooling, energy saving and equipment investing, is better than conventional packed cooling towers. However, no systematic thermodynamic numerical method could be found in the literature up to now. Based on the kinetic model and mass and heat transfer model, this paper has developed a one dimensional model for studying the motional process and evaporative cooling process occurring at the water droplet level in the SCT. The finite difference approach is used for three motional processes to obtain relative parameters in each different stage, and the possibility of the droplets being entrained outside the tower is fully analyzed. The accuracy of this model is checked by practical operational results from a full scale prototype in real conditions, and some exclusive factors that affect the cooling characteristics for the SCT are analyzed in detail. This study provides the theoretical foundation for practical application of the SCT in industry

System performance and economic analysis of solar-assisted cooling/heating system

KAUST Repository

Huang, B.J.; Wu, J.H.; Yen, R.H.; Wang, J.H.; Hsu, H.Y.; Hsia, C.J.; Yen, C.W.; Chang, J.M.

2011-01-01

The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling

Development of High Performance Cooling Modules in Notebook PC's

Science.gov (United States)

Tanahashi, Kosei

The CPU power consumption in Notebook PCs is increasing every year. Video chips and HDDs are also continually using larger power for higher performance. In addition, since miniaturization is desired, the mounting of components is becoming more and more dense. Accordingly, the cooling mechanisms are increasingly important. The cooling modules have to dissipate larger amounts of heat in the same environmental conditions. Therefore, high capacity cooling capabilities is needed, while low costs and high reliability must be retained. Available cooling methods include air or water cooling systems and the heat conduction method. The air cooling system is to transmit heat by a cooling fan often using a heat pipe. The water cooling one employs the water to carry heat to the back of the display, which offers a comparatively large cooling area. The heat conduction method is to transfer the heat by thermal conduction to the case. This article describes the development of new and comparatively efficient cooling devices offering low cost and high reliability for air cooling system. As one of the development techniques, the heat resistance and performance are measured for various parts and layouts. Each cooling system is evaluated in the same measurement environment. With regards to the fans, an optimal shape of the fan blades to maximize air flow is found by using CFD simulation, and prototypes were built and tested.

Comparative economic performance of selected passive solar heating and cooling technologies

Science.gov (United States)

Rutter, W.

1981-05-01

The economic performance of selected passive solar heating and cooling technologies which incorporate energy storage is assessed by using a set of uniform assumptions and methodologies. Where data are available, a given system is assessed at more than one geographical location. Results are obtained in the form of both payback period and net present value for residential applications, and in terms of net present value only for industrial/commercial uses. Results indicate that ventilated trombe walls, solar roof ponds, and certain night effect/floor storage strategies are cost effective, but night effect/rock bed cooling is not. Results also show that, although direct gain out-performs trombe walls in most parts of the country, both direct gain and trombe walls usually produce a net savings in the residential sector. Generally, however, tax regulations result in net economic loss for direct gain and trombe walls used to heat industrial and commercial buildings.

Performance Analysis of XCPC Powered Solar Cooling Demonstration Project

Science.gov (United States)

Widyolar, Bennett K.

A solar thermal cooling system using novel non-tracking External Compound Parabolic Concentrators (XCPC) has been built at the University of California, Merced and operated for two cooling seasons. Its performance in providing power for space cooling has been analyzed. This solar cooling system is comprised of 53.3 m2 of XCPC trough collectors which are used to power a 23 kW double effect (LiBr) absorption chiller. This is the first system that combines both XCPC and absorption chilling technologies. Performance of the system was measured in both sunny and cloudy conditions, with both clean and dirty collectors. It was found that these collectors are well suited at providing thermal power to drive absorption cooling systems and that both the coinciding of available thermal power with cooling demand and the simplicity of the XCPC collectors compared to other solar thermal collectors makes them a highly attractive candidate for cooling projects.

Effect of pre-cooling, with and without thigh cooling, on strain and endurance exercise performance in the heat.

Science.gov (United States)

Cotter, J D; Sleivert, G G; Roberts, W S; Febbraio, M A

2001-04-01

Body cooling before exercise (i.e. pre-cooling) reduces physiological strain in humans during endurance exercise in temperate and warm environments, usually improving performance. This study examined the effectiveness of pre-cooling humans by ice-vest and cold (3 degrees C) air, with (LC) and without (LW) leg cooling, in reducing heat strain and improving endurance performance in the heat (35 degrees C, 60% RH). Nine habitually-active males completed three trials, involving pre-cooling (LC and LW) or no pre-cooling (CON: 34 degrees C air) before 35-min cycle exercise: 20 min at approximately 65% VO2peak then a 15-min work-performance trial. At exercise onset, mean core (Tc, from oesophagus and rectum) and skin temperatures, forearm blood flow (FBF), heart rate (HR), and ratings of exertion, body temperature and thermal discomfort were lower in LW and LC than CON (Pcooling by ice-vest and cold air effectively reduced physiological and psychophysical strain and improved endurance performance in the heat, irrespective of whether thighs were warmed or cooled.

Performance of cooling installation for cyclotron Decy-13

International Nuclear Information System (INIS)

Edi Trijono Budisantoso; Suprapto; Sutadi

2015-01-01

Has been calculated the cooling installation performance of Decy-13 cyclotron. The cooling installation is analysed based on the technical specifications of each cooling component to proof the results of the design and implementation of installations meet the cooling requirement. Analysis of loss of pressure and flow rate in the piping installation is done empirically using Hazen-Williams equation while the analysis of heat transfer processes in the cooling tower is done using the help of psychometric charts that available. Cooling component consists of a condenser and associated piping systems with cooling towers and equipped with a pump to push the circulation of cooling. The calculations show that the installation of the condenser cooler uses the cooling tower LiangChi LBC-30 with a booster pump Grundfos 4 kW NF30-36T powered 47kW able to transfer heat with the coolant flow rate 136 lpm, input to output coolant pressure difference 2.1atm and the cooling temperature difference 5 °C. Conclusion of the calculation is the technical specifications of cooling components and installation already meets the needs of the cooling expected. (author)

Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

Science.gov (United States)

Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

2016-08-01

A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

Performance evaluation on cool roofs for green remodeling

Science.gov (United States)

Yun, Yosun; Cho, Dongwoo; Cho, Kyungjoo

2018-06-01

Cool roofs refer that maximize heat emission, and minimize the absorption of solar radiation energy, by applying high solar reflectance paints, or materials to roofs or rooftops. The application of cool roofs to existing buildings does not need to take structural issues into consideration, as rooftop greening, is an alternative that can be applied to existing buildings easily. This study installed a cool roofs on existing buildings, and evaluated the performances, using the results to propose certification standards for green remodeling, considering the cool roof-related standards.

Evaluation of advanced cooling therapy's esophageal cooling device for core temperature control.

Science.gov (United States)

Naiman, Melissa; Shanley, Patrick; Garrett, Frank; Kulstad, Erik

2016-05-01

Managing core temperature is critical to patient outcomes in a wide range of clinical scenarios. Previous devices designed to perform temperature management required a trade-off between invasiveness and temperature modulation efficiency. The Esophageal Cooling Device, made by Advanced Cooling Therapy (Chicago, IL), was developed to optimize warming and cooling efficiency through an easy and low risk procedure that leverages heat transfer through convection and conduction. Clinical data from cardiac arrest, fever, and critical burn patients indicate that the Esophageal Cooling Device performs very well both in terms of temperature modulation (cooling rates of approximately 1.3°C/hour, warming of up to 0.5°C/hour) and maintaining temperature stability (variation around goal temperature ± 0.3°C). Physicians have reported that device performance is comparable to the performance of intravascular temperature management techniques and superior to the performance of surface devices, while avoiding the downsides associated with both.

Cooling Performance of Natural Circulation for a Research Reactor

Energy Technology Data Exchange (ETDEWEB)

Park, Suki; Chun, J. H.; Yum, S. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

This paper deals with the core cooling performance by natural circulation during normal operation and a flow channel blockage event in an open tank-in-pool type research reactor. The cooling performance is predicted by using the RELAP5/ MOD3.3 code. The core decay heat is usually removed by natural circulation to the reactor pool water in open tank-in-pool type research reactors with the thermal power less than several megawatts. Therefore, these reactors have generally no active core cooling system against a loss of normal forced flow. In reactors with the thermal power less than around one megawatt, the reactor core can be cooled down by natural circulation even during normal full power operation. The cooling performance of natural circulation in an open tank-in-pool type research reactor has been investigated during the normal natural circulation and a flow channel blockage event. It is found that the maximum powers without void generation at the hot channel are around 1.16 MW and 820 kW, respectively, for the normal natural circulation and the flow channel blockage event.

Optimization of cooling tower performance analysis using Taguchi method

Directory of Open Access Journals (Sweden)

Ramkumar Ramakrishnan

2013-01-01

Full Text Available This study discuss the application of Taguchi method in assessing maximum cooling tower effectiveness for the counter flow cooling tower using expanded wire mesh packing. The experiments were planned based on Taguchi’s L27 orthogonal array .The trail was performed under different inlet conditions of flow rate of water, air and water temperature. Signal-to-noise ratio (S/N analysis, analysis of variance (ANOVA and regression were carried out in order to determine the effects of process parameters on cooling tower effectiveness and to identity optimal factor settings. Finally confirmation tests verified this reliability of Taguchi method for optimization of counter flow cooling tower performance with sufficient accuracy.

Performative building envelope design correlated to solar radiation and cooling energy consumption

Science.gov (United States)

Jacky, Thiodore; Santoni

2017-11-01

Climate change as an ongoing anthropogenic environmental challenge is predominantly caused by an amplification in the amount of greenhouse gases (GHGs), notably carbon dioxide (CO2) in building sector. Global CO2 emissions are emitted from HVAC (Heating, Ventilation, and Air Conditioning) occupation to provide thermal comfort in building. In fact, the amount of energy used for cooling or heating building is implication of building envelope design. Building envelope acts as interface layer of heat transfer between outdoor environment and the interior of a building. It appears as wall, window, roof and external shading device. This paper examines performance of various design strategy on building envelope to limit solar radiation and reduce cooling loads in tropical climate. The design strategies are considering orientation, window to wall ratio, material properties, and external shading device. This research applied simulation method using Autodesk Ecotect to investigate simultaneously between variations of wall and window ratio, shading device composition and the implication to the amount of solar radiation, cooling energy consumption. Comparative analysis on the data will determine logical variation between opening and shading device composition and cooling energy consumption. Optimizing the building envelope design is crucial strategy for reducing CO2 emissions and long-term energy reduction in building sector. Simulation technology as feedback loop will lead to better performative building envelope.

Cooling performance of a notebook PC mounted with heat spreader

Energy Technology Data Exchange (ETDEWEB)

Noh, H.K. [Electronics and Telecommunications Research Institute, Taejeon (Korea); Lim, K.B. [Hanbat National University, Taejeon (Korea); Park, M.H. [Korea Power Engineering Company (Korea)

2001-06-01

Parametric study to investigate the cooling performance of a notebook PC mounted with heat spreader has been numerically performed. Two case of air-blowing and air-exhaust at inlet were tested. The cooling effect on parameters such as, inlet velocities in the cases of air-blowing and air-exhaust, materials of heat spreader, and CPU powers were simulated for two cases. Cooling performance in the case of air-blowing was better than the case of air-exhaust. (author). 9 refs., 7 figs., 5 tabs.

Performance limit of daytime radiative cooling in warm humid environment

Directory of Open Access Journals (Sweden)

Takahiro Suichi

2018-05-01

Full Text Available Daytime radiative cooling potentially offers efficient passive cooling, but the performance is naturally limited by the environment, such as the ambient temperature and humidity. Here, we investigate the performance limit of daytime radiative cooling under warm and humid conditions in Okayama, Japan. A cooling device, consisting of alternating layers of SiO2 and poly(methyl methacrylate on an Al mirror, is fabricated and characterized to demonstrate a high reflectance for sunlight and a selective thermal radiation in the mid-infrared region. In the temperature measurement under the sunlight irradiation, the device shows 3.4 °C cooler than a bare Al mirror, but 2.8 °C warmer than the ambient of 35 °C. The corresponding numerical analyses reveal that the atmospheric window in λ = 16 ∼ 25 μm is closed due to a high humidity, thereby limiting the net emission power of the device. Our study on the humidity influence on the cooling performance provides a general guide line of how one can achieve practical passive cooling in a warm humid environment.

Dynamic behavior of radiant cooling system based on capillary tubes in walls made of high performance concrete

DEFF Research Database (Denmark)

Mikeska, Tomás; Svendsen, Svend

2015-01-01

elements made of high performance concrete. The influence of the radiant cooling system on the indoor climate of the test room in terms of the air, surface and operative temperatures and velocities was investigated.The results show that the temperature of the room air can be kept in a comfortable range...... using cooling water for the radiant cooling system with a temperature only about 4K lower than the temperature of the room air. The relatively high speed reaction of the designed system is a result of the slim construction of the sandwich wall elements made of high performance concrete. (C) 2015...... the small amount of fresh air required by standards to provide a healthy indoor environment.This paper reports on experimental analyses evaluating the dynamic behavior of a test room equipped with a radiant cooling system composed of plastic capillary tubes integrated into the inner layer of sandwich wall...

Optimal control and performance test of solar-assisted cooling system

KAUST Repository

Huang, B.J.; Yen, C.W.; Wu, J.H.; Liu, J.H.; Hsu, H.Y.; Petrenko, V.O.; Chang, J.M.; Lu, C.W.

2010-01-01

temperature. This will make the SACH always produce cooling effect even at lower solar radiation periods while the ejector performs at off-design conditions. The energy saving of A/C is experimentally shown 50-70% due to the cooling performance of ECS

Development and Performance of an Advanced Ejector Cooling System for a Sustainable Built Environment

Directory of Open Access Journals (Sweden)

Paulo ePereira

2015-06-01

Full Text Available Ejector refrigeration is a promising technology for the integration into solar driven cooling systems because of its relative simplicity and low initial cost. The major drawback of such a system is associated to its relatively low coefficient of performance (COP under variable operating conditions. In order to overcome this problem, an advanced ejector was developed that changes its geometrical features depending on the upstream and downstream conditions. This paper provides a short overview of the development process and results of a small cooling capacity (1.5 kW solar driven cooling system using a variable geometry ejector. During the design steps, a number of theoretical works have been carried out, including the selection of the working fluid, the determination of the geometrical requirements and prototype design. Based on the analysis, R600a was selected as working fluid. A prototype was constructed with two independent variable geometrical factors: the area ratio and the nozzle exit position. A test rig was also assembled in order to test the ejector performance under controlled laboratory conditions and to elaborate a control algorithm for the variable geometry. Ejector performance was assessed by calculation of cooling cycle COP, entrainment ratio and critical back pressure. The results show that for a condenser pressure of 3 bar, an 80% increase in the COP was obtained when compared to the performance of a fixed geometry ejector. Experimental COP values varied between 0.4 and 0.8, depending on operating conditions. Currently the cooling cycle is being integrated into a solar driven demonstration site for long term in situ assessment.

CARMENES-NIR channel spectrograph cooling system AIV: thermo-mechanical performance of the instrument

Science.gov (United States)

Becerril, S.; Mirabet, E.; Lizon, J. L.; Abril, M.; Cárdenas, C.; Ferro, I.; Morales, R.; Pérez, D.; Ramón, A.; Sánchez-Carrasco, M. A.; Quirrenbach, A.; Amado, P.; Ribas, I.; Reiners, A.; Caballero, J. A.; Seifert, W.; Herranz, J.

2016-07-01

CARMENES is the new high-resolution high-stability spectrograph built for the 3.5m telescope at the Calar Alto Observatory (CAHA, Almería, Spain) by a consortium formed by German and Spanish institutions. This instrument is composed by two separated spectrographs: VIS channel (550-1050 nm) and NIR channel (950- 1700 nm). The NIR-channel spectrograph's responsible is the Instituto de Astrofísica de Andalucía (IAACSIC). It has been manufactured, assembled, integrated and verified in the last two years, delivered in fall 2015 and commissioned in December 2015. One of the most challenging systems in this cryogenic channel involves the Cooling System. Due to the highly demanding requirements applicable in terms of stability, this system arises as one of the core systems to provide outstanding stability to the channel. Really at the edge of the state-of-the-art, the Cooling System is able to provide to the cold mass ( 1 Ton) better thermal stability than few hundredths of degree within 24 hours (goal: 0.01K/day). The present paper describes the Assembly, Integration and Verification phase (AIV) of the CARMENES-NIR channel Cooling System implemented at IAA-CSIC and later installation at CAHA 3.5m Telescope, thus the most relevant highlights being shown in terms of thermal performance. The CARMENES NIR-channel Cooling System has been implemented by the IAA-CSIC through very fruitful collaboration and involvement of the ESO (European Southern Observatory) cryo-vacuum department with Jean-Louis Lizon as its head and main collaborator. The present work sets an important trend in terms of cryogenic systems for future E-ELT (European Extremely Large Telescope) large-dimensioned instrumentation in astrophysics.

Effect of closed loop cooling water transit time on containment cooling

International Nuclear Information System (INIS)

Smith, R.P.; Vossahlik, J.E.; Goodwin, E.F.

1996-01-01

Long term containment cooling analyses in nuclear plant systems are usually conducted assuming a quasi steady-state process, that is, a steady state evaluation of the cooling system is completed for each calculational step. In reality, fluid transport in the system, and heat addition to system components may affect the heat removal rate of the system. Transient effects occurring during system startup may affect the maximum temperatures experienced in the system. It is important to ensure that such transient effects do not affect operation of the system (e.g., cause a high temperature trip). To evaluate the effect of fluid transit delays, a closed loop cooling water system model has been developed that incorporates the fluid transport times when determining the closed loop cooling system performance. This paper describes the closed loop cooling system model as implemented in the CONTEMPT-LT/028 code. The evaluation of the transient temperature response of the closed loop cooling system using the model is described. The paper also describes the effect of fluid transit time on the overall containment cooling performance

Experimental and numerical performance analysis of a converging channel heat exchanger for PV cooling

International Nuclear Information System (INIS)

Baloch, Ahmer A.B.; Bahaidarah, Haitham M.S.; Gandhidasan, Palanichamy; Al-Sulaiman, Fahad A.

2015-01-01

Highlights: • Effect of varying converging angle on temperature characteristics of PV surface studied. • Optical, CFD, thermal, and electrical models developed for the analysis. • Experimental measurements carried out for two configurations for June and December. • Using this cooling technique, maximum cell temperature reduction was 57.8%. • Maximum percentage improvement in power output was 35.5%. - Abstract: An experimental and numerical investigation of a cooling technique called as converging channel cooling intended to achieve low and uniform temperature on the surface of PV panel is presented in this paper. Experimental evaluation for an uncooled PV system and a converging channel cooled PV system was carried out subjected to the hot climate of Saudi Arabia for the month of June and December. Detailed modeling was performed using numerical analysis to investigate the effect of changing the converging angle on the thermal characteristics of the PV system. Based on the developed model, two degrees angle showed the best performance in terms of temperature distribution and average cell temperature with a standard deviation of 0.91 °C. A comprehensive system model was developed to assess the performance of PV systems numerically by coupling the optical, radiation, thermal, computational fluid dynamics, and electrical model. Thermal measurements for an uncooled PV showed cell temperature as high as 71.2 °C and 48.3 °C for the month of June and December, respectively. By employing converging cooling, cell temperature was reduced significantly to 45.1 °C for June and to 36.4 °C for December. Maximum percentage improvement in power output was 35.5% whereas maximum percentage increase in the conversion efficiency was 36.1% when compared to the performance of an uncooled PV system. For cost feasibility of an uncooled and cooled PV system, levelized cost of energy (LCE) analysis was performed using the annual energy yield simulation for both systems. LCE

Cooling performance of helium-gas/water coolers in HENDEL

International Nuclear Information System (INIS)

Inagaki, Yoshiyuki; Takada, Shoji; Hayashi, Haruyoshi; Kobayashi, Toshiaki; Ohta, Yukimaru; Shimomura, Hiroaki; Miyamoto, Yoshiaki

1994-01-01

The helium engineering demonstration loop (HENDEL) has four helium-gas/water coolers where the cooling water flows in the tubes and helium gas on the shell side. Their cooling performance was studied using the operational data from 1982 to 1991. The heat transfer of helium gas on the shell was obtained for segmental and step-up baffle type coolers. Also, the change with operation time was investigated. The cooling performance was lowered by the graphite powder released from the graphite components for several thousand hours and thereafter recovered because the graphite powder from the components was reduced and the powder in the cooler shell was blown off during the operation. (orig.)

Parametric study of closed wet cooling tower thermal performance

Science.gov (United States)

Qasim, S. M.; Hayder, M. J.

2017-08-01

The present study involves experimental and theoretical analysis to evaluate the thermal performance of modified Closed Wet Cooling Tower (CWCT). The experimental study includes: design, manufacture and testing prototype of a modified counter flow forced draft CWCT. The modification based on addition packing to the conventional CWCT. A series of experiments was carried out at different operational parameters. In view of energy analysis, the thermal performance parameters of the tower are: cooling range, tower approach, cooling capacity, thermal efficiency, heat and mass transfer coefficients. The theoretical study included develops Artificial Neural Network (ANN) models to predicting various thermal performance parameters of the tower. Utilizing experimental data for training and testing, the models simulated by multi-layer back propagation algorithm for varying all operational parameters stated in experimental test.

Effect of Half Time Cooling on Thermoregulatory Responses and Soccer-Specific Performance Tests

OpenAIRE

Yang Zhang; Svetlana Nepocatych; Charlie P. Katica; Annie B. Collins,; Catalina Casaru,; Gytis Balilionis; Jesper Sjökvist; Phillip A. Bishop

2014-01-01

This study examined two active coolings (forearm and hand cooling, and neck cooling) during a simulated half-time recovery on thermoregulatory responses and subsequent soccer-specific exercise performance. Following a 45-min treadmill run in the heat, participants (N=7) undertook 15-min recovery with either passive cooling, forearm and hand cooling, or neck cooling in a simulated cooled locker room environment. After the recovery, participants performed a 6×15-m sprint test and Yo-Yo Intermit...

Cooling During Exercise: An Overlooked Strategy for Enhancing Endurance Performance in the Heat.

Science.gov (United States)

Stevens, Christopher J; Taylor, Lee; Dascombe, Ben J

2017-05-01

It is well established that endurance performance is negatively affected by environmental heat stress due to a complex interaction of physical, physiological and psychological alterations. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling (cooling prior to an exercise test), and as such this has become a well-established ergogenic practice for endurance athletes. However, the use of mid-cooling (cooling during an exercise test) has received considerably less research attention in comparison, despite recent evidence to suggest that the advantage gained from mid-cooling may outweigh that of pre-cooling. A range of mid-cooling strategies are beneficial for endurance performance in the heat, including the ingestion of cold fluids and ice slurry, both with and without menthol, as well as cooling of the neck and face region via a cooling collar or water poured on the head and face. The combination of pre-cooling and mid-cooling has also been effective, but few comparisons exist between the timing and type of such interventions. Therefore, athletes should experiment with a range of suitable mid-cooling strategies for their event during mock competition scenarios, with the aim to determine their individual tolerable limits and performance benefits. Based on current evidence, the effect of mid-cooling on core temperature appears largely irrelevant to any subsequent performance improvements, while cardiovascular, skin temperature, central nervous system function and psychophysiological factors are likely involved. Research is lacking on elite athletes, and as such it is currently unclear how this population may benefit from mid-cooling.

Performance analysis of solar air cooled double effect LiBr/H2O absorption cooling system in subtropical city

International Nuclear Information System (INIS)

Li, Zeyu; Ye, Xiangyang; Liu, Jinping

2014-01-01

Highlights: • The meteorological data during the working period of air conditioning was measured. • The suitable working range of collector temperature of system was gotten. • The characteristic of hourly and monthly total efficiency of system were obtained. • The yearly performance of system was calculated. - Abstract: Due to the absence of cooling tower and independent on water, the air cooled solar double effect LiBr/H 2 O absorption cooling system is more convenient to be used in commercial building and household use. The performance with collector temperature is an important field for such system. The paper mainly deals with the performance with collector temperature for the solar air cooled double effect LiBr/H 2 O absorption cooling system in subtropical city. The parameters of system are: aperture area of collector array is 27 m 2 , tilted angle of collector with respect to the horizontal plane is 20 toward to south evaporator temperature is 5 °C and the cooling capacity is 20 kW. The simulation is based on the meteorological data of monthly typical day which was summarized from a year round measured data. A corresponding parametric model was developed. The hourly and average performance with the collector temperature for monthly typical day was obtained and discussed. It was found that the suitable working range of inlet temperature of collector is 110–130 °C to improve performance and lower the risk of crystallization. The difference of hourly total efficiency in 9:00–16:00 is less, and the monthly total efficiency from May to October is approximate. The yearly performance of system including total efficiency, cooling capacity per area of collector and solar fraction was given. Furthermore, the effect of effectiveness of heat exchanger and pressure drop on total efficiency and solar fraction was studied and compared. The paper can serve as a preliminary investigation of solar air cooled double effect LiBr/H 2 O absorption cooling system in

Cooling and performance recovery of trained athletes: a meta-analytical review.

Science.gov (United States)

Poppendieck, Wigand; Faude, Oliver; Wegmann, Melissa; Meyer, Tim

2013-05-01

Cooling after exercise has been investigated as a method to improve recovery during intensive training or competition periods. As many studies have included untrained subjects, the transfer of those results to trained athletes is questionable. Therefore, the authors conducted a literature search and located 21 peer-reviewed randomized controlled trials addressing the effects of cooling on performance recovery in trained athletes. For all studies, the effect of cooling on performance was determined and effect sizes (Hedges' g) were calculated. Regarding performance measurement, the largest average effect size was found for sprint performance (2.6%, g = 0.69), while for endurance parameters (2.6%, g = 0.19), jump (3.0%, g = 0.15), and strength (1.8%, g = 0.10), effect sizes were smaller. The effects were most pronounced when performance was evaluated 96 h after exercise (4.3%, g = 1.03). Regarding the exercise used to induce fatigue, effects after endurance training (2.4%, g = 0.35) were larger than after strength-based exercise (2.4%, g = 0.11). Cold-water immersion (2.9%, g = 0.34) and cryogenic chambers (3.8%, g = 0.25) seem to be more beneficial with respect to performance than cooling packs (-1.4%, g= -0.07). For cold-water application, whole-body immersion (5.1%, g = 0.62) was significantly more effective than immersing only the legs or arms (1.1%, g = 0.10). In summary, the average effects of cooling on recovery of trained athletes were rather small (2.4%, g = 0.28). However, under appropriate conditions (whole-body cooling, recovery from sprint exercise), postexercise cooling seems to have positive effects that are large enough to be relevant for competitive athletes.

Thermodynamic analysis of turbine blade cooling on the performance of gas turbine cycle

International Nuclear Information System (INIS)

Sarabchi, K.; Shokri, M.

2002-01-01

Turbine inlet temperature strongly affects gas turbine performance. Today blade cooling technologies facilitate the use of higher inlet temperatures. Of course blade cooling causes some thermodynamic penalties that destroys to some extent the positive effect of higher inlet temperatures. This research aims to model and evaluate the performance of gas turbine cycle with air cooled turbine. In this study internal and transpiration cooling methods has been investigated and the penalties as the result of gas flow friction, cooling air throttling, mixing of cooling air flow with hot gas flow, and irreversible heat transfer have been considered. In addition, it is attempted to consider any factor influencing actual conditions of system in the analysis. It is concluded that penalties due to blade cooling decrease as permissible temperature of the blade surface increases. Also it is observed that transpiration method leads to better performance of gas turbine comparing to internal cooling method

The effects of regeneration temperature of the desiccant wheel on the performance of desiccant cooling cycles for greenhouse thermally insulated

Science.gov (United States)

Rjibi, Amel; Kooli, Sami; Guizani, Amenaallah

2018-05-01

The use of solar energy for cooling greenhouses in the hot period in Mediterranean climate is an important issue. Desiccant evaporative cooling (DEC) system is advantageous because it uses a low grade thermal energy and preserves the merits to be friendly environmentally technology. In this paper, a numerical investigation was carried out on a desiccant cooling system powered by air solar collectors coupled to an insulated greenhouse. The influence of the regeneration temperature on the air stream properties at every system component state point was studied. The performance of the desiccant cooling system was evaluated in terms of thermal and electric coefficient of performance. Results show that the best performance of the system (COPel = 14 and COPth = 0.94) was obtained for a 60 °C regeneration temperature and a supply flow rate ratio of 0.2. An economic analysis shows that the use of the DEC system for greenhouse cooling is attractive and profitable since the payback period is 1 years. The use of the proposed system allows saving 9396 kWh/year of electric energy compared to conventional system.

Field evaluation of performance of radiant heating/cooling ceiling panel system

DEFF Research Database (Denmark)

Li, Rongling; Yoshidomi, Togo; Ooka, Ryozo

2015-01-01

heating/coolingceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiantheating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus,this study aims to not only clarify the system performance but also to share our...... experience and our resultsfor them to serve as a reference for other similar projects. Here, the system performance in relation toits heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient fromwater to room was 3.7 W/(m2K) and 4.8 W/(m2K) for heating and cooling cases...

Effect mechanism of air deflectors on the cooling performance of dry cooling tower with vertical delta radiators under crosswind

International Nuclear Information System (INIS)

Zhao, Yuanbin; Long, Guoqing; Sun, Fengzhong; Li, Yan; Zhang, Cuijiao; Liu, Jiabin

2015-01-01

Highlights: • A 3D numerical model was set for NDDCTV to study the effect of air deflectors. • The air deflectors improve the tower performance by 1.375 °C at u c = 6 m/s for a case. • The air deflectors reduce the air inflow deviation angle θ d at most delta entries. • The reduced θ d can improve the cooling performance of former deteriorated columns. • Both the radial inflow air velocity and θ d impact the cooling performance of delta. - Abstract: To study the effect mechanism of air deflectors on dry cooling tower, a three dimensional numerical model was established, with full consideration of the delta structure. The accuracy and credibility of dry cooling tower numerical model were validated. By numerical model, the average air static pressure and the average radial inflow air velocity were computed and analyzed at delta air entry, sector air entry and exit faces. By the air inflow deviation angle θ d , the effect of air deflectors on the aerodynamic field around tower was analyzed. The water exit temperatures of θ −1 columns, θ +2 columns and cooling sectors were also presented to clarify the effect of air deflectors. It was found that the air deflectors improved the aerodynamic field around cooling columns. The reduced air inflow deviation degree at delta entry improved the cooling performance of deteriorated columns. Referring to the radial inflow air velocity u ra and the air inflow deviation degree at delta entry, the effect mechanism of air deflectors are clarified under crosswind

Preliminary tests of a model of cooling-pond thermal performance

International Nuclear Information System (INIS)

Hicks, B.B.; Wesely, M.L.; Wilczek, J.

1975-01-01

Experiments performed during recent years at the cooling pond complex at the Dresden nuclear power station have been designed to improve our understanding of the fundamental properties of thermal exchange at a warm-water surface. To a considerable extent, the field studies have been successful in that they have shown that modern micrometeorological techniques can be successfully applied to the demanding circumstances of an industrial cooling lake at temperature of at least 40 0 C. The intent of these studies has been to create a set of parameterization schemes good enough to allow simulation of the performance of the Dresden cooling lake without adjustment of numerical constants. An obvious extension of these studies, and one of the goals of the cooling-pond research program as presently stated, is to obtain an accurate numerical simulation of thermal performance of ponds with use of the improved formulations that have resulted from the experimental work at the Dresden lake. The computer model is divided into two sections and can be used to test the sensitivity of predicted performance to variations in procedures for determining the thermal transfer from the surface

Effect of wrist cooling on aerobic and anaerobic performance in elite sportsmen.

Science.gov (United States)

Krishnan, Anup; Singh, Krishan; Sharma, Deep; Upadhyay, Vivekanand; Singh, Amit

2018-01-01

Body cooling has been used to increase sporting performance and enhance recovery. Several studies have reported improvement in exercise capacities using forearm and hand cooling or only hand cooling. Wrist cooling has emerged as a portable light weight solution for precooling prior to sporting activity. The Astrand test for aerobic performance and the Wingate test for anaerobic performance are reliable and accurate tests for performance assessment. This study conducted on elite Indian athletes analyses the effects of wrist precooling on aerobic and anaerobic performance as tested by the Astrand test and the Wingate test before and after wrist precooling. 67 elite sportsmen were administered Wingate and Astrand test under standardised conditions with and without wrist precooling using a wrist cooling device (dhamaSPORT). Paired t -test was applied to study effect on aerobic [VO 2 (ml/min/kg)] and anaerobic performance [peak power (W/kg) and average power (W/kg)] and Cohen's d was used to calculate effect size of wrist precooling. After wrist precooling, significant increase of 0.22 ( p  = 0.014, 95% CI: 0.047, 0.398) in peak power (W/kg) and 0.22 ( p  effective in aerobic performance. Wrist cooling effect size was smaller in VO 2 (Cohen's d  = 0.21), peak power (Cohen's d  = 0.31) and it was larger in average power (Cohen's d  = 0.71). Results show wrist precooling significantly improves anaerobic than aerobic performance of elite sportsmen.

Study on performance prediction and energy saving of indirect evaporative cooling system

Energy Technology Data Exchange (ETDEWEB)

Yoo, Seong Yeon; Kim, Tae Ho; Kim, Myung Ho [Dept. of Mechanical Design Engineering, Chungnam National University, Daejeon (Korea, Republic of)

2015-09-15

The purpose of this study is to predict the performance of an indirect evaporative cooling system, and to evaluate its energy saving effect when applied to the exhaust heat recovery system of an air-handling unit. We derive the performance correlation of the indirect evaporative cooling system using a plastic heat exchanger based on experimental data obtained in various conditions. We predict the variations in the performance of the system for various return and outdoor air conditioning systems using the obtained correlation. We also analyze the energy saving of the system realized by the exhaust heat recovery using the typical meteorological data for several cities in Korea. The average utilization rate of the sensible cooling system for the exhaust heat recovery is 44.3% during summer, while that of the evaporative cooling system is 96.7%. The energy saving of the evaporative cooling system is much higher compared to the sensible cooling system, and was about 3.89 times the value obtained in Seoul.

An exergy analysis on the performance of a counterflow wet cooling tower

International Nuclear Information System (INIS)

Muangnoi, Thirapong; Asvapoositkul, Wanchai; Wongwises, Somchai

2007-01-01

Cooling towers are used to extract waste heat from water to atmospheric air. An energy analysis is usually used to investigate the performance characteristics of cooling tower. However, the energy concept alone is insufficient to describe some important viewpoints on energy utilization. In this study, an exergy analysis is used to indicate exergy and exergy destruction of water and air flowing through the cooling tower. Mathematical model based on heat and mass transfer principle is developed to find the properties of water and air, which will be further used in exergy analysis. The model is validated against experimental data. It is noted from the results that the amount of exergy supplied by water is larger than that absorbed by air, because the system produces entropy. To depict the utilizable exergy between water and air, exergy of each working fluid along the tower are presented. The results show that water exergy decreases continuously from top to bottom. On the other hand, air exergy is expressed in terms of convective and evaporative heat transfer. Exergy of air via convective heat transfer initially loses at inlet and slightly recovers along the flow before leaving the tower. However, exergy of air via evaporative heat transfer is generally high and able to consume exergy supplied by water. Exergy destruction is defined as the difference between water exergy change and air exergy change. It reveals that the cooling processes due to thermodynamics irreversibility perform poorly at bottom and gradually improve along the height of the tower. The results show that the lowest exergy destruction is located at the top of the tower

Experimental evaluation of cooling efficiency of the high performance cooling device

Science.gov (United States)

Nemec, Patrik; Malcho, Milan

2016-06-01

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.

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.

Influence of precooling cooling air on the performance of a gas turbine combined cycle

Energy Technology Data Exchange (ETDEWEB)

Kwon, Ik Hwan; Kang, Do Won; Kang, Soo Young; Kim, Tong Seop [Inha Univ., Incheon (Korea, Republic of)

2012-02-15

Cooling of hot sections, especially the turbine nozzle and rotor blades, has a significant impact on gas turbine performance. In this study, the influence of precooling of the cooling air on the performance of gas turbines and their combined cycle plants was investigated. A state of the art F class gas turbine was selected, and its design performance was deliberately simulated using detailed component models including turbine blade cooling. Off design analysis was used to simulate changes in the operating conditions and performance of the gas turbines due to precooling of the cooling air. Thermodynamic and aerodynamic models were used to simulate the performance of the cooled nozzle and rotor blade. In the combined cycle plant, the heat rejected from the cooling air was recovered at the bottoming steam cycle to optimize the overall plant performance. With a 200K decrease of all cooling air stream, an almost 1.78% power upgrade due to increase in main gas flow and a 0.70 percent point efficiency decrease due to the fuel flow increase to maintain design turbine inlet temperature were predicted.

Numerical and Experimental Investigation on the Performance of a Thermoelectric Cooling Automotive Seat

Science.gov (United States)

Su, Chuqi; Dong, Wenbin; Deng, Yadong; Wang, Yiping; Liu, Xun

2018-06-01

Heating, ventilating and air conditioning (HVAC) is the most significant auxiliary load in vehicles and largely increases extra emissions. Therefore, thermoelectric cooling automotive seat, a relatively new technology, is used in an attempt to reduce HVAC consumption and improve thermal comfort. In this study, three design schemes of the thermoelectric cooler (TEC) are proposed. Then the numerical simulation is used to analyze their heat transfer performance, and evaluate the improvement of the seat cooling in terms of the occupant back thermal comfort. Moreover, an experiment is conducted to validate the accuracy of the simulation results. The experimental results show that: (1) an average reduction in air temperature of 4°C in 60 s is obtained; (2) the temperature of the occupant's back drops from 33.5°C to 25.7°C in cooperation with the HVAC system; (3) back thermal comfort is greatly improved. As expected, the thermoelectric cooling automotive seat is able to provide an improvement in the occupant's thermal comfort at a reduced energy consumption rate, which makes it promising for vehicular application.

Analytical Modelling of the Effects of Different Gas Turbine Cooling Techniques on Engine Performance =

Science.gov (United States)

Uysal, Selcuk Can

In this research, MATLAB SimulinkRTM was used to develop a cooled engine model for industrial gas turbines and aero-engines. The model consists of uncooled on-design, mean-line turbomachinery design and a cooled off-design analysis in order to evaluate the engine performance parameters by using operating conditions, polytropic efficiencies, material information and cooling system details. The cooling analysis algorithm involves a 2nd law analysis to calculate losses from the cooling technique applied. The model is used in a sensitivity analysis that evaluates the impacts of variations in metal Biot number, thermal barrier coating Biot number, film cooling effectiveness, internal cooling effectiveness and maximum allowable blade temperature on main engine performance parameters of aero and industrial gas turbine engines. The model is subsequently used to analyze the relative performance impact of employing Anti-Vortex Film Cooling holes (AVH) by means of data obtained for these holes by Detached Eddy Simulation-CFD Techniques that are valid for engine-like turbulence intensity conditions. Cooled blade configurations with AVH and other different external cooling techniques were used in a performance comparison study. (Abstract shortened by ProQuest.).

On the optimum performance of forced draft counter flow cooling towers

International Nuclear Information System (INIS)

Soeylemez, M.S.

2004-01-01

A thermo-hydraulic performance optimization analysis is presented, yielding simple algebraic formula for estimating the optimum performance point of counter current mechanical draft wet cooling towers. The effectiveness-Ntu method is used in the present study, together with the derivation of psychometric properties of moist air based on a numerical approximation method, for thermal performance analysis of wet cooling towers of the counter flow type

Performance Recovery of Natural Draft Dry Cooling Systems by Combined Air Leading Strategies

Directory of Open Access Journals (Sweden)

Weijia Wang

2017-12-01

Full Text Available The cooling efficiency of natural draft dry cooling system (NDDCS are vulnerable to ambient winds, so the implementation of measures against the wind effects is of great importance. This work presents the combined air leading strategies to recover the flow and heat transfer performances of NDDCS. Following the energy balance among the exhaust steam, circulating water, and cooling air, numerical models of natural draft dry cooling systems with the combined air leading strategies are developed. The cooling air streamlines, volume effectiveness, thermal efficiency and outlet water temperature for each cooling delta of the large-scale heat exchanger are obtained. The overall volume effectiveness, average outlet water temperature of NDDCS and steam turbine back pressure are calculated. The results show that with the air leading strategies inside or outside the dry-cooling tower, the thermo-flow performances of natural draft dry cooling system are improved under all wind conditions. The combined inner and outer air leading strategies are superior to other single strategy in the performance recovery, thus can be recommended for NDDCS in power generating units.

Performance evaluation of an indirect pre-cooling evaporative heat exchanger operating in hot and humid climate

International Nuclear Information System (INIS)

Cui, X.; Chua, K.J.; Islam, M.R.; Ng, K.C.

2015-01-01

Highlights: • An IEHX is introduced as a pre-cooling unit for humid tropical climate. • A computational model is developed to investigate the performance of IEHX. • The air treatment process with condensation from the product air is studied. • The hybrid system shows an appreciable energy saving potential. - Abstract: A hybrid system, that combines an indirect evaporative heat exchanger (IEHX) and a vapor compression system, is introduced for humid tropical climate application. The chief purpose of the IEHX is to pre-cool the incoming air for vapor compression system. In the IEHX unit, the outdoor humid air in the product channel may potentially condense when heat is exchanged with the room exhaust air. A computational model has been developed to theoretically investigate the performance of an IEHX with condensation from the product air by employing the room exhaust air as the working air. We validated the model by comparing its temperature distribution and predicted heat flux against experimental data acquired from literature sources. The numerical model showed good agreement with the experimental findings with maximum average discrepancy of 9.7%. The validated model was employed to investigate the performance of two types of IEHX in terms of the air treatment process, temperature and humidity distribution, cooling effectiveness, cooling capacity, and energy consumption. Simulation results have indicated that the IEHX unit is able to fulfill 47% of the cooling load for the outdoor humid air while incurring a small amount of fan power. Consequently, the hybrid system is able to realize significant energy savings

CEGB research on the effects of fouling of plastic packings on natural draught cooling tower performance

International Nuclear Information System (INIS)

Winter, R.J.

1989-01-01

Plastic film packings were first used in CEGB natural draught cooling towers in 1985. Since then, cooling towers at seven power stations have been repacked using various commercial designs of plastic packing, with generally satisfactory results in economic terms. However, fouling of all the packings has occurred to some extent, ranging from very thin films on the surface of the sheets, which actually enhances performance, to heavy and voluminous formations which severely constrict the inter-sheet passages, causing performance loss and threatening the structural integrity of the whole fill. At CERL, methods have been developed to relate the degree of fouling to the thermal performance loss. This information is enabling accurate calculations to be made of the economics of repacking. Samples of fouled packing from operation towers are tested using the Experimental Cooling Tower at the Central Electricity Research Laboratories at Leatherhead. A systematic investigation is also underway of the changes in pressure drop and mass transfer coefficients which take place as fouling develops, using progressively-fouled packing samples from a purpose-built Packing Fouling Facility located at one of the power stations. The performance data obtained is fed-back into models by which the effect of high fouling loadings on various packings is calculated, enabling packing economic life to be predicted

Evaluation on Long-term Cooling of CANDU after Sump Blockage using MARS-KS

Energy Technology Data Exchange (ETDEWEB)

Yu, Seon Oh; Cho, Yong Jin [KINS, Daejeon (Korea, Republic of); Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of)

2016-05-15

There was a real incident that part of the fibrous insulation debris stripped by steam jet was transported to the pool and clogged the intake strainers of the drywell spray system, which revealed a weakness in the defense-in-depth concept which under other circumstances could have led to the ECCS failing to provide coolant to the core. Since the above Barseback-2 incident in 1992, lots of the international activities have been carried out to identify essential parameters and physical phenomena and to promote consensus on the technical issues, important for safety and possible paths for their resolution. In nuclear power plant under operation, if an unplanned reactor trip or a power reduction occurs, operators are required to maintain the reactor in a stable state according to emergency operating procedure (EOP) and to take diagnosis and appropriate mitigation actions if necessary. Subject to the EOP of Wolsong unit 1 (the first Korean PHWR NPP) under LOCA, intact or broken loops are diagnosed using the available plant information such as pressure and temperature of outlet headers. For the intact loop, effective long-term cooling is envisioned through the operation of shutdown cooling system as implemented in the EOP. In this work, the adequacy of long-term cooling during the recirculation phase of LOCA was evaluated under the postulated condition of the reduced flow path of the recirculation sump due to the inflow of substantial amount of debris released by the break flow with high energy. For the intact loop, although the incipience of boiling in the fuel channel was evaluated to occur, the effective long-term cooling can be achieved through the shutdown cooling system as guided in the EOP.

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

Performance analysis of a ground-assisted direct evaporative cooling air conditioner

Energy Technology Data Exchange (ETDEWEB)

Heidarinejad, Ghassem; Khalajzadeh, Vahid [Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran); Delfani, Shahram [Building and Housing Research Center (BHRC), P O Box 13145-1696, Tehran (Iran)

2010-11-15

In this paper, the results of performance analysis of a ground-assisted hybrid evaporative cooling system in Tehran have been discussed. A Ground Coupled Circuit (GCC) provides the necessary pre-cooling effects, enabling a Direct Evaporative Cooler (DEC) that cools the air even below its wet-bulb temperature. The GCC includes four vertical ground heat exchangers (GHE) which were arrayed in series configuration. In order to have an accurate prediction of the optimum performance of a GCC, a computational fluid dynamic simulation was performed. Simulation results revealed that the combination of GCC and DEC system could provide comfort condition whereas DEC alone did not. Based on the simulation results the cooling effectiveness of a hybrid system is more than 100%. Thus, this novel hybrid system could decrease the air temperature below the ambient wet-bulb temperature. This environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems. (author)

Investigation of Loop Seal Clearing Phenomena for the ATLAS SBLOCA Long Term Cooling Test using TRACE and MARS-KS

Energy Technology Data Exchange (ETDEWEB)

Hwang, Min Jeong; Park, M. H.; Marigomen Ralph; Sim, S. K. [Environment and Energy Technology, Daejeon (Korea, Republic of)

2016-10-15

During Design Certificate(DC) review of the APR1400, USNRC raised a long term cooling safety issue on the effect of loop seal clearing during cold leg Small Break Loss Of Coolant Accident(SBLOCA) due to relatively deep cross-over loop compared to the US PWRs. The objective of this study is thus to investigate the loop seal clearing phenomena during cold leg slot break SBLOCA long term cooling and resolve the safety issue on the SBLOCA long term cooling related to the APR1400 DC. TRACE and MARS-KS were used to predict the test results and to perform sensitivity studies for the SBLOCA loop seal clearing phenomena. The calculation shows that the TRACE code well predict the sequence of Test LTC-CL-04R. However, compared to the experiment, the TRACE over predicts the primary pressure due to smaller break flow prediction. MARS-KS well predicts major thermal hydraulic parameters during the transient with reasonable agreement. MARS-KS better predicts ATLAS LTC-CL-04R test data with a good agreement than the TRACE due to better prediction of the break flow. Overall, compared to the experiment, the TRACE and MARS-KS Codes show a discrepancy in predicting the loop seal clearing and reformation time. Both TRACE and MARS-KS correctly predicts core water level and fuel cladding temperatures. From this study, it can be said that even though APR1400 cross-over leg design has slightly deeper loop seals, the effect on the safety of the SBLOCA long term cooling is minimal compared to the SBLOCA cladding failure criteria. Further study on the SBLOCA loop seal clearing phenomena is needed.

Cooling with Superfluid Helium

Energy Technology Data Exchange (ETDEWEB)

Lebrun, P; Tavian, L [European Organization for Nuclear Research, Geneva (Switzerland)

2014-07-01

The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics.

Review of RSG-GAS secondary cooling pump performance

International Nuclear Information System (INIS)

Marsahala, Y.B.

1999-01-01

The control system of RSG-GAS secondary pump is the study for the operation existence of RSG-GAS secondary pump. The research is about characteristic of the secondary pump and its control system. The measuring of characteristic parameter of secondary cooling pump was being done while the pump running. The pump was loading with capacity 1950 m3/hr. with ambient temperature 28.5 oC. The fault effect of public grid (PLN) such as the fluctuation of both voltage and frequency likes voltage drops (dip). Supply block out that effect of the electric motor performances directly will be analyzed. How far those faults will effect the overall performance of secondary cooling system. Analyzing. Will be done according to the control system was installed. Has be done to find the direct effects of the motor performances against the motor rotation fluctuation which run from 1450 rpm to 1475 rpm. The using of start-delta starting method with delay time about 6 seconds, is enough or not to reduce the inrush starting current also analyzed in this paper. From the research can be obtained that in the steady state condition , the electric motor runs with both power and current are still under tolerances permitted. According to the analyzed data above, it will be consider that the control system of secondary pump would be modified or not. Therefore the analyzed data can show the characteristic curve of the secondary cooling system performance

influence of sub-cooling on the energy performance of two eco

African Journals Online (AJOL)

PUBLICATIONS1

frigerants, consistently exhibited better performance than R22 in sub-cooling heat ... 2014 Kwame Nkrumah University of Science and Technology (KNUST) ... sales volume among all refrigerants. .... The sub-cooling heat exchanger affects the.

On how high performers keep cool brains in situations of cognitive overload.

Science.gov (United States)

Jaeggi, Susanne M; Buschkuehl, Martin; Etienne, Alex; Ozdoba, Christoph; Perrig, Walter J; Nirkko, Arto C

2007-06-01

What happens in the brain when we reach or exceed our capacity limits? Are there individual differences for performance at capacity limits? We used functional magnetic resonance imaging (fMRI) to investigate the impact of increases in processing demand on selected cortical areas when participants performed a parametrically varied and challenging dual task. Low-performing participants respond with large and load-dependent activation increases in many cortical areas when exposed to excessive task requirements, accompanied by decreasing performance. It seems that these participants recruit additional attentional and strategy-related resources with increasing difficulty, which are either not relevant or even detrimental to performance. In contrast, the brains of the high-performing participants "keep cool" in terms of activation changes, despite continuous correct performance, reflecting different and more efficient processing. These findings shed light on the differential implications of performance on activation patterns and underline the importance of the interindividual-differences approach in neuroimaging research.

MARS Simulation of Air Cooling Heat Exchanger Connected with PAFS

Energy Technology Data Exchange (ETDEWEB)

Jeon, Seong-Su; Hong, Soon-Joon [FNC Technology Co., Yongin (Korea, Republic of); Bae, Sung-Won; Kwon, Tae-Soon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

Current working time of PAFS cannot meet the required 72 hours cooling capability for the long term Station Black-Out (SBO) situation. Therefore, it is required to improve the design of PAFS for the long term cooling. In order to ensure the long term cooling of PAFS, the heat exchanger tube should be submerged in the water of the PAFS pool. It can be achieved by condensing the steam vented from the PAFS pool. The Air Cooling Heat Exchanger (ACHX) is installed above the PAFS pool. It is expected that the ACHX condenses the steam vented from the PAFS pool and delays the depletion time of the water in the PCCT. Therefore, this paper introduces the MARS-KS1.4 modeling of the ACHX and the performance analysis results on the PAFS connected with the ACHX. For the long term cooling with PAFS, KAERI proposed a new passive air-water combined cooling system. In this study, the modeling of the ACHX and the performance analysis on the PAFS connected with the ACHX were carried out with MARS. MARS predicted the behavior of main thermal-hydraulic variables of ACHX reasonably. Then, it was found that the long term cooling of PAFS could be achieved by the installation of the ACHX in which the tube length is 6 m and the number of tubes is 8000.

Improvement of Cooling Performance of a Compact Thermoelectric Air Conditioner Using a Direct Evaporative Cooling System

Science.gov (United States)

Tipsaenporm, W.; Lertsatitthanakorn, C.; Bubphachot, B.; Rungsiyopas, M.; Soponronnarit, S.

2012-06-01

This paper presents the results of tests carried out to investigate the potential application of a direct evaporative cooling (DEC) system for improving the performance of a compact thermoelectric (TE) air conditioner. The compact TE air conditioner is composed of three TE modules. The cold and hot sides of the TE modules were fixed to rectangular fin heat sinks. The DEC system produced cooling air that was used to assist the release of heat from the heat sinks at the hot side of the TE modules. The results showed that the cooling air dry bulb temperature from the DEC system achieved drops of about 5.9°C in parallel with about a 33.4% rise in relative humidity. The cooling efficiency of the DEC system varies between 72.1% and 81.5%. It increases the cooling capacity of the compact TE air conditioner from 53.0 W to 74.5 W. The 21.5 W (40.6%) increase represents the difference between the compact air conditioner operating with ambient air flowing through the TE module's heat sinks, and the compact air conditioner operating with the cooler air from the DEC system flowing through the TE module's heat sinks. In both scenarios, electric current of 4.5 A was supplied to the TE modules. It also has been experimentally proven that the coefficient of performance (COP) of the compact TE air conditioner can be improved by up to 20.9% by incorporating the DEC system.

Materials Performance in Sodium-Cooled Fast Reactors: Past, Present, and Future

International Nuclear Information System (INIS)

Natesan, K.; Li Meimei

2013-01-01

• This paper gives an overview of the requirements, selection, and performance of materials for in-core and out-of-core components in SFRs. • Globally, sodium-cooled fast reactors have been designed, built, and operated in several countries. A substantial database exists for the existing materials on their functional and mechanical performance. • The 60-yr design life of the SFR presents a significant challenge to the development of database, extrapolation/prediction of long-term performance, and high-temperature design methodology for the structural components. • Licensing of SFR requires a valid assessment of the environmental effects (irradiation, thermal aging, and sodium) on materials performance. • Advanced materials such as, ODS alloys for cladding, Gr91 and 92 F/M steels, and austenitic alloys such as NF709 for structures can improve the economy, safety, and flexibility of SFRs. A substantial database is needed for all these materials and global effort is underway to develop the needed information through experimentation and modeling

Design and performance prediction of an adsorption heat pump with multi-cooling tubes

Energy Technology Data Exchange (ETDEWEB)

Wang, D.C.; Zhang, J.P. [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China)

2009-05-15

Widespread application of adsorption heat pumps has been delayed not only by poor heat and mass transfer performance but also by low operating reliability because high vacuum must be maintained in the adsorption cooling system, especially in a water system. An adsorption cooling tube is a tube in which an adsorber, a condenser and an evaporator are all completely housed to construct a small scale adsorption cooling unit. In this work, an adsorption cooling tube and an adsorption heat pump with multi-cooling tubes are designed. A theoretical model is built to simulate the performance of the designed chiller. According to the results, the coefficient of performance and specific cooling power reach about 0.5 and 85 W/kg adsorbent, respectively, at the hot water temperature of 85 C. These results indicate that the designed heat pump in this work would provide a better choice if the operating reliability became crucial for an adsorption heat pump. (author)

Design and performance prediction of an adsorption heat pump with multi-cooling tubes

International Nuclear Information System (INIS)

Wang, D.C.; Zhang, J.P.

2009-01-01

Widespread application of adsorption heat pumps has been delayed not only by poor heat and mass transfer performance but also by low operating reliability because high vacuum must be maintained in the adsorption cooling system, especially in a water system. An adsorption cooling tube is a tube in which an adsorber, a condenser and an evaporator are all completely housed to construct a small scale adsorption cooling unit. In this work, an adsorption cooling tube and an adsorption heat pump with multi-cooling tubes are designed. A theoretical model is built to simulate the performance of the designed chiller. According to the results, the coefficient of performance and specific cooling power reach about 0.5 and 85 W/kg adsorbent, respectively, at the hot water temperature of 85 deg. C. These results indicate that the designed heat pump in this work would provide a better choice if the operating reliability became crucial for an adsorption heat pump.

Dry cooling with night cool storage to enhance solar power plants performance in extreme conditions areas

International Nuclear Information System (INIS)

Muñoz, J.; Martínez-Val, J.M.; Abbas, R.; Abánades, A.

2012-01-01

Highlights: ► Solar thermo-electric power plants with thermal storage for condenser cooling. ► Technology to mitigate the negative effect on Rankine cycles of the day-time high temperatures in deserts. ► Electricity production augmentation in demand-peak hours by the use of day-night temperature difference. -- Abstract: Solar thermal power plants are usually installed in locations with high yearly average solar radiation, often deserts. In such conditions, cooling water required for thermodynamic cycles is rarely available. Moreover, when solar radiation is high, ambient temperature is very high as well; this leads to excessive condensation temperature, especially when air-condensers are used, and decreases the plant efficiency. However, temperature variation in deserts is often very high, which drives to relatively low temperatures during the night. This fact can be exploited with the use of a closed cooling system, so that the coolant (water) is chilled during the night and store. Chilled water is then used during peak temperature hours to cool the condenser (dry cooling), thus enhancing power output and efficiency. The present work analyzes the performance improvement achieved by night thermal cool storage, compared to its equivalent air cooled power plant. Dry cooling is proved to be energy-effective for moderately high day–night temperature differences (20 °C), often found in desert locations. The storage volume requirement for different power plant efficiencies has also been studied, resulting on an asymptotic tendency.

Thermodynamic modelling and performance study of an engine waste heat driven adsorption cooling for automotive air-conditioning

International Nuclear Information System (INIS)

Ali, Syed Muztuza; Chakraborty, Anutosh

2015-01-01

Waste heat from engine can be utilized to drive an adsorption cooling system for air conditioning purposes in the vehicle cabin, which not only improves the fuel economy but also reduces the carbon footprint. It is also important to reduce the size of the adsorption bed to adopt the adsorption technology for air-conditioning applications in passenger cars, buses and trucks or even trains. In this article, we present a two stage indirect exhaust heat recovery system of automotive engine employing an effective lumped parameter model to simulate the dynamic behaviors of an adsorption chiller that ranges from the transient to the cyclic steady states. The thermodynamic framework of adsorption chiller is developed from the rigor of mass and energy balances of each component of the system and experimentally confirmed isotherms and kinetics data of various adsorbent–adsorbate pairs. The performance factors are calculated in terms of COP (Coefficient of Performance) and SCP (Specific Cooling Power) for different operating parameters such as cycle time, exhaust gas temperatures, cooling water temperatures and flow rates. From the simulation results, it is found that the exhaust energy of a six cylinder 3000 cc private car is able to produce nearly 3 kW of cooling power for the car cabin. It is also observed that the driving heat source temperature does not remain constant throughout the cycle time unlike the conventional adsorption chiller, and the hot water temperatures as driving source vary from 65 to 95 °C. CaCl 2 -in-silica gel–water system is found better in terms of COP and SCP as compared with other adsorbents – water systems. - Highlights: • Adsorption cooling for car air conditioning. • Thermodynamic frameworks with adsorption isotherms and kinetics. • Various adsorbents such as silica gel, zeolites (AQSOA-Z01, Z-02), CaCl 2 -in-silica gel are tested. • Cooling power for car cabin employing waste heat recovery.

Assessment of the forced air-cooling performance for cylindrical lithium-ion battery packs: A comparative analysis between aligned and staggered cell arrangements

International Nuclear Information System (INIS)

Yang, Naixing; Zhang, Xiongwen; Li, Guojun; Hua, Dong

2015-01-01

An appropriate cell arrangement plays significant role to design a highly efficient cooling system for the lithium-ion battery pack. This paper performs a comparative analysis of thermal performances on different arrangements of cylindrical cells for a LiFePO 4 battery pack. A thermal model for the battery pack is developed and is solved in couple with the governing equations of fluid flow in the numerical simulations. The experiments for model validation are conducted on a single cell of the battery pack with forced-air cooling system. The effects of longitudinal and transverse spacing on the cooling performances are analyzed for the battery pack with the aligned and the staggered arrays. Under a specified flow rate of cooling air, the maximum temperature rise is proportional to the longitudinal interval for the staggered arrays, while it is in inverse for the aligned arrangement. Increasing the transverse interval leads to the increase of the battery temperature rise for both aligned and staggered arrangements. By trade-off the design requirements (maximum temperature rise, temperature uniformity, power requirement and cooling index), an appropriate solution in term of the optimal combination of the longitudinal interval, transverse interval, and air inlet width is obtained for the aligned arrangement. - Highlights: • Forced air-cooling performance for cylindrical lithium-ion battery is evaluated. • Thermal performances for aligned and staggered cell arrangements are compared. • Geometric optimization is investigated for the battery air-cooling system

Water spray cooling technique applied on a photovoltaic panel: The performance response

International Nuclear Information System (INIS)

Nižetić, S.; Čoko, D.; Yadav, A.; Grubišić-Čabo, F.

2016-01-01

Highlights: • An experimental study was conducted on a monocrystalline photovoltaic panel (PV). • A water spray cooling technique was implemented to determine PV panel response. • The experimental results showed favorable cooling effect on the panel performance. • A feasibility aspect of the water spray cooling technique was also proven. - Abstract: This paper presents an alternative cooling technique for photovoltaic (PV) panels that includes a water spray application over panel surfaces. An alternative cooling technique in the sense that both sides of the PV panel were cooled simultaneously, to investigate the total water spray cooling effect on the PV panel performance in circumstances of peak solar irradiation levels. A specific experimental setup was elaborated in detail and the developed cooling system for the PV panel was tested in a geographical location with a typical Mediterranean climate. The experimental result shows that it is possible to achieve a maximal total increase of 16.3% (effective 7.7%) in electric power output and a total increase of 14.1% (effective 5.9%) in PV panel electrical efficiency by using the proposed cooling technique in circumstances of peak solar irradiation. Furthermore, it was also possible to decrease panel temperature from an average 54 °C (non-cooled PV panel) to 24 °C in the case of simultaneous front and backside PV panel cooling. Economic feasibility was also determined for of the proposed water spray cooling technique, where the main advantage of the analyzed cooling technique is regarding the PV panel’s surface and its self-cleaning effect, which additionally acts as a booster to the average delivered electricity.

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

Numerical investigation of thermal performance of a water-cooled mini-channel heat sink for different chip arrangement

Energy Technology Data Exchange (ETDEWEB)

Tikadar, Amitav, E-mail: amitav453@gmail.com; Hossain, Md. Mahamudul; Morshed, A. K. M. M. [Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka, 1000 (Bangladesh)

2016-07-12

Heat transfer from electronic chip is always challenging and very crucial for electronic industry. Electronic chips are assembled in various manners according to the design conditions and limitationsand thus the influence of chip assembly on the overall thermal performance needs to be understand for the efficient design of electronic cooling system. Due to shrinkage of the dimension of channel and continuous increment of thermal load, conventional heat extraction techniques sometimes become inadequate. Due to high surface area to volume ratio, mini-channel have the natural advantage to enhance convective heat transfer and thus to play a vital role in the advanced heat transfer devices with limited surface area and high heat flux. In this paper, a water cooled mini-channel heat sink was considered for electronic chip cooling and five different chip arrangements were designed and studied, namely: the diagonal arrangement, parallel arrangement, stacked arrangement, longitudinal arrangement and sandwiched arrangement. Temperature distribution on the chip surfaces was presented and the thermal performance of the heat sink in terms of overall thermal resistance was also compared. It is found that the sandwiched arrangement of chip provides better thermal performance compared to conventional in line chip arrangement.

Performance characteristic of hybrid cooling system based on cooling pad and evaporator

Science.gov (United States)

Yoon, J. I.; Son, C. H.; Choi, K. H.; Kim, Y. B.; Sung, Y. H.; Roh, S. J.; Kim, Y. M.; Seol, S. H.

2018-01-01

In South Korea, most of domestic animals such as pigs and chickens might die due to thermal diseases if they are exposed to the high temperature consistently. In order to save them from the heat wave, numerous efforts have been carried out: installing a shade net, adjusting time of feeding, spraying mist and setting up a circulation fan. However, these methods have not shown significant improvements. Thus, this study proposes a hybrid cooling system combining evaporative cooler and air-conditioner in order to resolve the conventional problems caused by the high temperature in the livestock industry. The problem of cooling systems using evaporative cooling pads is that they are not effective for eliminating huge heat load due to their limited capacity. And, temperature of the supplied air cannot be low enough compared to conventional air-conditioning systems. On the other hand, conventional air-conditioning systems require relatively expensive installation cost, and high operating cost compared to evaporative cooling system. The hybrid cooling system makes up for the lack of cooling capacity of the evaporative cooler by employing the conventional air-conditioner. Additionally, temperature of supplied air can be lowered enough. In the hybrid cooling system, induced air by a fan is cooled by the evaporation of water in the cooling pad, and it is cooled again by an evaporator in the air-conditioner. Therefore, the more economical operation is possible due to additionally obtained cooling capacity from the cooling pads. Major results of experimental analysis of hybrid cooling system are as follows. The compressor power consumption of the hybrid cooling system is about 23% lower, and its COP is 17% higher than that of the conventional air-conditioners. Regarding the condition of changing ambient temperature, the total power consumption decreased by about 5% as the ambient temperature changed from 28.7°C to 31.7°C. Cooling capacity and COP also presented about 3% and 1

Performance of cold compressors in a cooling system of an R and D superconducting coil cooled with subcooled helium

International Nuclear Information System (INIS)

Hamaguchi, S.; Imagawa, S.; Yanagi, N.; Takahata, K.; Maekawa, R.; Mito, T.

2006-01-01

The helical coils of large helical device (LHD) have been operated in saturated helium at 4.4 K and plasma experiments have been carried out at magnetic fields lower than 3 T for 8 years. Now, it is considered that the cooling system of helical coils will be improved to enhance magnetic fields in 2006. In the improvement, the helical coils will be cooled with subcooled helium and the operating temperature of helical coils will be lowered to achieve the designed field of 3 T and enhance cryogenic stabilities. Two cold compressors will be used in the cooling system of helical coils to generate subcooled helium. In the present study, the performance of cold compressors has been investigated, using a cooling system of R and D coil, to apply cold compressors to the cooling system of helical coils. Actual surge lines of cold compressors were observed and the stable operation area was obtained. Automatic operations were also performed within the area. In the automatic operations, the suitable pressure of a saturated helium bath, calculated from the rotation speed of the 1st cold compressor, was regulated by bypass valve. From these results, stable operations will be expected in the cooling system of helical coils

Utilization of control rod drive (CRD) system for long term core cooling

International Nuclear Information System (INIS)

Huerta B, A.

1991-01-01

In this paper we consider an application of Probabilistic Risk Assessment (PRA) to risk management. Foreseeable risk management strategies to prevent core damage are constrained by the availability of first line systems as well as support systems. The actual trend in the evaluation of risk management options can be performed in a number of ways. An example is the identification of back-up systems which could be used to perform the same safety functions. In this work we deal with the evaluation of the feasibility, for BWR's, to use the Control Rod Drive system to maintain an adequate reactor core long term cooling in some accident sequences. This preliminary evaluation is carried out as a part of the Internal Events Analysis for Laguna Verde Nuclear Power Plant (LVNPP) that is currently under way by the Mexican Nuclear Regulatory Body. This analysis addresses the evaluation and incorporation of all the systems, including the safety related and the back-up non safety related systems, that are available for the operator in order to prevent core damage. As a part of this analysis the containment venting capability is also evaluated as a back-up of the containment heat removal function. This will prevent the primary containment overpressurization and loss of certain core cooling systems. A selection of accident sequences in which the Control Rod Drive system could be used to mitigate the accident and prevent core damage are discussed. A personal computer transient analysis code is used to carry out thermohydraulic simulations in order to evaluate the Control Rod Drive system performance, the corresponding results are presented. Finally, some preliminary conclusions are drawn. (author). 9 refs, 5 figs

16 CFR Appendix H to Part 305 - Cooling Performance and Cost for Central Air Conditioners

Science.gov (United States)

2010-01-01

... RULEâ) Pt. 305, App. H Appendix H to Part 305—Cooling Performance and Cost for Central Air Conditioners... Split System Units Central Air Conditioners (Cooling Only): All capacities 10.9 23.0 Heat Pumps (Cooling... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Cooling Performance and Cost for Central Air...

Development of a novel rotary desiccant cooling cycle with isothermal dehumidification and regenerative evaporative cooling using thermodynamic analysis method

International Nuclear Information System (INIS)

La, D.; Li, Y.; Dai, Y.J.; Ge, T.S.; Wang, R.Z.

2012-01-01

A novel rotary desiccant cooling cycle is proposed and studied using thermodynamic analysis method. The proposed cycle integrates the technologies of isothermal dehumidification and regenerative evaporative cooling, which are beneficial for irreversibility reduction. Thermodynamic investigation on the basic rotary desiccant cooling cycle shows that the exergy efficiency of the basic cycle is only 8.6%. The processes of desiccant dehumidification and evaporative cooling, which are essentially the basis for rotary desiccant cooling, affect the exergy performance of the cycle greatly and account for about one third of the total exergy destruction. The proposed cycle has potential to improve rotary desiccant cooling technology. It is advantageous in terms of both heat source utilization rate and space cooling capacity. The exergy efficiency of the new cycle is enhanced significantly to 29.1%, which is about three times that of the ventilation cycle, and 60% higher than that of the two-stage rotary desiccant cooling cycle. Furthermore, the regeneration temperature is reduced from 80 °C to about 60 °C. The corresponding specific exergy of the supply air is increased by nearly 30% when compared with the conventional cycles. -- Highlights: ► A novel rotary desiccant cooling cycle is developed using thermodynamic analysis method. ► Isothermal dehumidification and regenerative evaporative cooling have been integrated. ► The cycle is advantageous in terms of both heat source utilization rate and space cooling capacity. ► Cascaded energy utilization is beneficial for cycle performance improvement. ► Upper limits, which will be helpful to practical design and optimization, are obtained.

Optimization of cooling tower performance analysis using Taguchi method

OpenAIRE

Ramkumar Ramakrishnan; Ragupathy Arumugam

2013-01-01

This study discuss the application of Taguchi method in assessing maximum cooling tower effectiveness for the counter flow cooling tower using expanded wire mesh packing. The experiments were planned based on Taguchi’s L27 orthogonal array .The trail was performed under different inlet conditions of flow rate of water, air and water temperature. Signal-to-noise ratio (S/N) analysis, analysis of variance (ANOVA) and regression were carried out in order to determine the effects of process...

Performance of the Conduction-Cooled LDX Levitation Coil

Science.gov (United States)

Michael, P. C.; Schultz, J. H.; Smith, B. A.; Titus, P. H.; Radovinsky, A.; Zhukovsky, A.; Hwang, K. P.; Naumovich, G. J.; Camille, R. J.

2004-06-01

The Levitated Dipole Experiment (LDX) was developed to study plasma confinement in a dipole magnetic field. Plasma is confined in the magnetic field of a 680-kg Nb3Sn Floating Coil (F-coil) that is electromagnetically supported at the center of a 5-m diameter by 3-m tall vacuum chamber. The Levitation Coil (L-coil) is a 2800-turn, double pancake winding that supports the weight of the F-coil and controls its vertical position within the vacuum chamber. The use of high-temperature superconductor (HTS) Bi-2223 for the L-coil minimizes the electrical and cooling power needed for levitation. The L-coil winding pack and support plate are suspended within the L-coil cryostat and cooled by conduction to a single-stage cryocooler rated for 25-W heat load at approximately 20 K. The coil current leads consist of conduction-cooled copper running from room temperature to 80 K and a pair of commercially-available, 150-A HTS leads. An automatically filled liquid-nitrogen reservoir provides cooling for the coil's radiation shield and for the leads' 80-K heat stations. This paper discusses the L-coil system design and its observed cryogenic performance.

Sensitivity of energy and exergy performances of heating and cooling systems to auxiliary components

DEFF Research Database (Denmark)

Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

2017-01-01

. Different forms of energy (electricity and heat) are used in heating and cooling systems, and therefore, a holistic approach to system design and analysis is needed. In particular, distribution systems use electricity as a direct input to pumps and fans, and to other components. Therefore, exergy concept......Heating and cooling systems in buildings consist of three main subsystems: heating/cooling plant, distribution system, and indoor terminal unit. The choice of indoor terminal unit determines the characteristics of the distribution system and the heating and cooling plants that can be used...... should be used in design and analysis of the whole heating and cooling systems, in addition to the energy analysis. In this study, water-based (floor heating and cooling, and radiator heating) and air-based (air heating and cooling) heating and cooling systems were compared in terms of their energy use...

Warm Up and Cool Down: Reduce Risk of Injury and Improve Athletic Performance

Science.gov (United States)

... exercise, but more research is needed. Although there's controversy about whether warming up and cooling down can ... your agreement to the Terms and Conditions and Privacy Policy linked below. Terms and Conditions Privacy Policy ...

Statistical multi-model approach for performance assessment of cooling tower

International Nuclear Information System (INIS)

Pan, Tian-Hong; Shieh, Shyan-Shu; Jang, Shi-Shang; Tseng, Wen-Hung; Wu, Chan-Wei; Ou, Jenq-Jang

2011-01-01

This paper presents a data-driven model-based assessment strategy to investigate the performance of a cooling tower. In order to achieve this objective, the operations of a cooling tower are first characterized using a data-driven method, multiple models, which presents a set of local models in the format of linear equations. Satisfactory fuzzy c-mean clustering algorithm is used to classify operating data into several groups to build local models. The developed models are then applied to predict the performance of the system based on design input parameters provided by the manufacturer. The tower characteristics are also investigated using the proposed models via the effects of the water/air flow ratio. The predicted results tend to agree well with the calculated tower characteristics using actual measured operating data from an industrial plant. By comparison with the design characteristic curve provided by the manufacturer, the effectiveness of cooling tower can be obtained in the end. A case study conducted in a commercial plant demonstrates the validity of proposed approach. It should be noted that this is the first attempt to assess the cooling efficiency which is deviated from the original design value using operating data for an industrial scale process. Moreover, the evaluated process need not interrupt the normal operation of the cooling tower. This should be of particular interest in industrial applications.

Assessment of cooling performance of a diffuse plate in HYPER target

International Nuclear Information System (INIS)

Tak, N. I.; Song, T. Y.; Park, W. S.

2001-01-01

Major difficulties are caused by cooling problems of the beam window of the spallation target in designing of 1000 MWth HYPER (HYbrid Power Extraction Reactor). Numerical studies to improve the cooling capability of the window are on the way. In the present work, numerical analysis has been performed to assess the cooling performance of a diffuse plate in HYPER target conditions. The fluid dynamics code CFX 4 was used for the analysis. Heat depositions in the window and the target were calculated by the LAHEAT code systems and used as input data of the CFX 4 code. The diffuse plate was modeled as a porous media having three porosities. The analysis was performed for various design parameters (the porosity, the thickness of a diffuse plate, the distance between the plate and the window). The results of CFX 4 show that ∼10 .deg. C of the reduction of the maximum window temperature, which is not enough for the HYPER design, can be obtained with a diffuse plate. Therefore, another methods such as an introduction of a bypass injection have to be considered to improve the window cooling

Experimental performance of evaporative cooling pad systems in greenhouses in humid subtropical climates

International Nuclear Information System (INIS)

Xu, J.; Li, Y.; Wang, R.Z.; Liu, W.; Zhou, P.

2015-01-01

Highlights: • Experimental performance of evaporative cooling in humid climate is investigated. • 5 working modes are studied in the greenhouse. • Vertical and horizontal temperature and relative humidity variations are analysed. • Indoor temperature can be kept in required level by proper working modes. - Abstract: To solve the overheating problem caused by the solar radiation and to keep the indoor temperature and humidity at a proper level for plants or crops, cooling technologies play vital role in greenhouse industry, and among which evaporative cooling is one of the most commonly-used methods. However, the main challenge of the evaporative cooling is its suitability to local climatic and agronomic condition. In this study, the performance of evaporative cooling pads was investigated experimentally in a 2304-m 2 glass multi-span greenhouse in Shanghai in the southeast of China. Temperature and humidity distributions were measured and reported for different working modes, including the use of evaporative cooling alone and the use of evaporative cooling with shading or ventilation. These experiments were conducted in humid subtropical climates where were considered unfavourable for evaporative cooling pad systems. Quantified analyses from the energy perspective are also made based on the experimental results and the evaporative cooling fan–pad system is demonstrated to be an effective option for greenhouse cooling even in the humid climate. Suggestions and possible solutions for further improving the performance of the system are proposed. The results of this work will be useful for the optimisation of the energy management of greenhouses in humid climates and for the validation of the mathematical model in future work

An analytical model on thermal performance evaluation of counter flow wet cooling tower

Directory of Open Access Journals (Sweden)

Wang Qian

2017-01-01

Full Text Available This paper proposes an analytical model for simultaneous heat and mass transfer processes in a counter flow wet cooling tower, with the assumption that the enthalpy of the saturated air is a linear function of the water surface temperature. The performance of the proposed analytical model is validated in some typical cases. The validation reveals that, when cooling range is in a certain interval, the proposed model is not only comparable with the accurate model, but also can reduce computational complexity. In addition, with the proposed analytical model, the thermal performance of the counter flow wet cooling towers in power plants is calculated. The results show that the proposed analytical model can be applied to evaluate and predict the thermal performance of counter flow wet cooling towers.

Performance test of solar-assisted ejector cooling system

KAUST Repository

Huang, Bin-Juine; Ton, Wei-Zhe; Wu, Chen-Chun; Ko, Hua-Wei; Chang, Hsien-Shun; Hsu, Hang-Yuen; Liu, Jen-Hao; Wu, Jia-Hung; Yen, Rue-Her

2014-01-01

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

Comparative study of the performance of the M-cycle counter-flow and cross-flow heat exchangers for indirect evaporative cooling – Paving the path toward sustainable cooling of buildings

International Nuclear Information System (INIS)

Zhan, Changhong; Duan, Zhiyin; Zhao, Xudong; Smith, Stefan; Jin, Hong; Riffat, Saffa

2011-01-01

This paper provides a comparative study of the performance of cross-flow and counter-flow M-cycle heat exchangers for dew point cooling. It is recognised that evaporative cooling systems offer a low energy alternative to conventional air conditioning units. Recently emerged dew point cooling, as the renovated evaporative cooling configuration, is claimed to have much higher cooling output over the conventional evaporative modes owing to use of the M-cycle heat exchangers. Cross-flow and counter-flow heat exchangers, as the available structures for M-cycle dew point cooling processing, were theoretically and experimentally investigated to identify the difference in cooling effectiveness of both under the parallel structural/operational conditions, optimise the geometrical sizes of the exchangers and suggest their favourite operational conditions. Through development of a dedicated computer model and case-by-case experimental testing and validation, a parametric study of the cooling performance of the counter-flow and cross-flow heat exchangers was carried out. The results showed the counter-flow exchanger offered greater (around 20% higher) cooling capacity, as well as greater (15%–23% higher) dew-point and wet-bulb effectiveness when equal in physical size and under the same operating conditions. The cross-flow system, however, had a greater (10% higher) Energy Efficiency (COP). As the increased cooling effectiveness will lead to reduced air volume flow rate, smaller system size and lower cost, whilst the size and cost are the inherent barriers for use of dew point cooling as the alternation of the conventional cooling systems, the counter-flow system is considered to offer practical advantages over the cross-flow system that would aid the uptake of this low energy cooling alternative. In line with increased global demand for energy in cooling of building, largely by economic booming of emerging developing nations and recognised global warming, the research

Performance analysis for minimally nonlinear irreversible refrigerators at finite cooling power

Science.gov (United States)

Long, Rui; Liu, Zhichun; Liu, Wei

2018-04-01

The coefficient of performance (COP) for general refrigerators at finite cooling power have been systematically researched through the minimally nonlinear irreversible model, and its lower and upper bounds in different operating regions have been proposed. Under the tight coupling conditions, we have calculated the universal COP bounds under the χ figure of merit in different operating regions. When the refrigerator operates in the region with lower external flux, we obtained the general bounds (0 present large values, compared to a relative small loss from the maximum cooling power. If the cooling power is the main objective, it is desirable to operate the refrigerator at a slightly lower cooling power than at the maximum one, where a small loss in the cooling power induces a much larger COP enhancement.

Thermodynamic performance analysis of gas-fired air-cooled adiabatic absorption refrigeration systems

International Nuclear Information System (INIS)

Wang, L.; Chen, G.M.; Wang, Q.; Zhong, M.

2007-01-01

In China, the application of small size gas-fired air-cooled absorption refrigeration systems as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand in Chinese big cities and lack of water resources. However, for conventional air-cooled absorption refrigeration systems, it is difficult to enhance the heat and mass transfer process in the falling film absorber, and may cause problems, for example, remarkable increase of pressure, temperature and concentration in the generators, risk of crystallization, acceleration of corrosion, degradation of performance, and so on. This paper presents a gas-fired air-cooled adiabatic absorption refrigeration system using lithium bromide-water solutions as its working fluid, which is designed with a cooling capacity of 16 kW under standard conditions. The system has two new features of waste heat recovery of condensed water from generator and an adiabatic absorber with an air cooler. Performance simulation and characteristic analysis are crucial for the optimal control and reliability of operation in extremely hot climates. A methodology is presented to simulate thermodynamic performance of the system. The influences of outdoor air temperature on operation performances of the system are investigated

Decrement in manual arm performance during whole body cooling.

Science.gov (United States)

Giesbrecht, G G; Bristow, G K

1992-12-01

Six subjects performed three manual arm tasks: 1) prior to immersion in 8 degrees C water; 2) soon after immersion to the neck, but prior to any decrease in core temperature; and 3) every 15 min until core temperatures decreased 2-4.5 degrees C. The tasks were speed of flexion and extension of the fingers, handgrip strength and manual dexterity. There was no immediate effect of cold immersion; however, all scores decreased significantly after core temperature decreased 0.5 degrees C. Further decrease in core temperature was associated with a progressive impairment of performance, although at a slower rate than during the first 0.5 degrees C decrease. Flexion and extension of the fingers was affected relatively more than handgrip strength or manual dexterity. Decrement in performance is a result of peripheral cooling on sensorimotor function with a probable additional effect of central cooling on cerebral function.

Passive cooling during transport of asphyxiated term newborns

Science.gov (United States)

O’Reilly, Deirdre; Labrecque, Michelle; O’Melia, Michael; Bacic, Janine; Hansen, Anne; Soul, Janet S

2014-01-01

Objective To evaluate the efficacy and safety of passive cooling during transport of asphyxiated newborns. Study Design Retrospective medical record review of newborns with perinatal asphyxia transported for hypothermia between July 2007 and June 2010. Results Forty-three newborns were transported, 27 of whom were passively cooled. Twenty (74%) passively cooled newborns arrived with axillary temperature between 32.5 and 34.5 °C. One newborn (4%) arrived with a subtherapeutic temperature, and 6 (22%) had temperatures >34.5 °C. Time from birth to hypothermia was significantly shorter among passively cooled newborns compared with newborns not cooled (215 vs. 327 minutes, pencephalopathy results in significantly earlier achievement of effective therapeutic hypothermia without significant adverse events. PMID:23154670

Performance analysis on utilization of sky radiation cooling energy for space cooling. Part 2; Hosha reikyaku riyo reibo system ni kansuru kenkyu. 2

Energy Technology Data Exchange (ETDEWEB)

Marushima, S; Saito, T [Tohoku University, Sendai (Japan)

1996-10-27

Studies have been made about a heat accumulation tank type cooling system making use of radiation cooling that is a kind of natural energy. The daily operating cycle of the cooling system is described below. A heat pump air conditioner performs cooling during the daytime and the exhaust heat is stored in a latent heat accumulation tank; the heat is then used for the bath and tapwater in the evening; at night radiation cooling is utilized to remove the heat remnant in the tank for the solidification of the phase change material (PCM); the solidified PCM serves as the cold heat source for the heat pump air conditioner to perform cooling. The new system decelerates urban area warming because it emits the cooler-generated waste heat not into the atmosphere but into space taking advantage of radiation cooling. Again, the cooler-generated waste heat may be utilized for energy saving and power levelling. For the examination of nighttime radiation cooling characteristics, CaCl2-5H2O and Na2HPO4-12H2O were tested as the PCM. Water was used as the heating medium. In the case of a PCM high in latent heat capacity, some work has to be done for insuring sufficient heat exchange for it by, for instance, rendering the flow rate low. The coefficient of performance of the system discussed here is three times higher than that of the air-cooled type heat pump system. 8 refs., 5 figs., 4 tabs.

Convective Performance of Nanofluids in Commercial Electronics Cooling Systems

International Nuclear Information System (INIS)

Roberts, N.A.; Walker, D.G.

2010-01-01

Nanofluids are stable engineered colloidal suspensions of a small fraction of nanoparticles in a base fluid. Nanofluids have shown great promise as heat transfer fluids over typically used base fluids and fluids with micron sized particles. Suspensions with micron sized particles are known to settle rapidly and cause clogging and damage to the surfaces of pumping and flow equipment. These problems are dramatically reduced in nanofluids. In the current work we investigate the performance of different volume loadings of water-based alumina nanofluids in a commercially available electronics cooling system. The commercially available system is a water block used for liquid cooling of a computational processing unit. The size of the nanoparticles in the study is 20-30 nm. Results show an enhancement in convective heat transfer due to the addition of nanoparticles in the commercial cooling system with volume loadings of nanoparticles up to 1.5% by volume. The enhancement in the convective performance observed is similar to what has been reported in well controlled and understood systems and is commensurate with bulk models. The current nanoparticle suspensions showed visible signs of settling which varied from hours to weeks depending on the size of the particles used.

Parametric Study on an Initial Cooling Performance in the KALIMER-600

International Nuclear Information System (INIS)

Han, Ji-Woong; Eoh, Jae-Hyuk; Lee, Tae-Ho; Kim, Seong-O

2009-01-01

Decay heat removal is very important in a nuclear power plant. The KALIMER-600, Korea Advanced Liquid MEtal Reactor, employs the PDRC(Passive Decay heat Removal Circuit) to remove the decay heat. DHX(Decay Heat eXchanger) in the PDRC of KALIMER-600 is disposed in the DHX support barrel located in the hot pool region. Each DHX support barrel has the lower end communicating with the cold pool such that the sodium free surface inside the barrel is maintained with the same level of the cold pool using the pumping head of the PHTS(Primary Heat Transport System) pumps. Consequently, DHX is not in direct contact with the cold pool sodium during a normal plant operation. Under transient conditions such as the loss of a normal heat sink accident, free surface outside the barrel rises up due to the expansion of the sodium induced by the core decay heat during the initial stage cooling. When it overflows into the cold pool through the DHX support barrel the heat removal via DHX is initiated and the second stage cooling begins. In order to secure the safety of a reactor until the activation of a second stage cooling by PDRC, it is very important to suppress the core temperature rising by an enhancement of the initial cooling performance. In this study the parametric investigations have been applied to reveal the effect of various design parameters on the initial cooling performance. The various design parameters such as coastdown flow, IHX(Intermediate Heat eXchanger) elevation, heat transfer via CCS (Cavity Cooling System) were considered. The numerical approaches based on a multidimensional analysis can be utilized as a useful tool to investigate overall transient behaviors within a pool. In this research the COMMIX-1AR/P code is utilized as a transient analysis tool in KALIMER-600 after a shut down. This study will provide the basic design information to improve the initial cooling performance in the KALIMER-600

Evaluation of the RSG-GAS cooling tower performance

International Nuclear Information System (INIS)

Suroso

2003-01-01

Utilization of RSG-GAS reactor should be operated as efficiently as possible, so that reactor operation planning using one line primary coolant can be anticipated. To analyze the performance of the RSG-GAS cooling tower with one line primary coolant doing by using same data from 10 MW thermal reactor operation. The result were then compare to those achieved using CATHENA code. The results indicated that, for design condition the ratio of water flowrate to air is (L/G) 1.52 and number transfer unit (NTU) is 0.348. For operation condition, the average of L/G and NTU are respectively 1.37 and 0,348. Moreover the results achieved by the code showed that L/G and NTU are respectively 1.35 and 0,302. The performance of cooling tower achieved operation condition and the code results are respectively 91% and 72%. This means that the calculated results are lower than measurement results

Cooling and heating performances of a CO2 heat pump with the variations of operating conditions

International Nuclear Information System (INIS)

Baek, Chang Hyun; Lee, Eung Chan; Kang, Hun; Kim, Yong Chan; Cho, Hong Hyun

2008-01-01

Since operating conditions are significantly different for heating and cooling mode operations in a CO 2 heat pump system, it is difficult to optimize the performance of the CO 2 cycle. In addition, the performance of a CO 2 heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO 2 heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%

Performance of an optimally contact-cooled high-heat-load mirror at the APS

International Nuclear Information System (INIS)

Cai, Z.; Khounsary, A.; Lai, B.; McNulty, I.; Yun, W.

1998-01-01

X-ray undulator beamlines at third-generation synchrotrons facilities use either a monochromator or a mirror as the first optical element. In this paper, the thermal and optical performance of an optimally designed contact-cooled high-heat-load x-ray mirror used as the first optical element on the 2ID undulator beamline at the Advanced Photon Source (APS) is reported. It is shown that this simple and economical mirror design can comfortably handle the high heat load of undulator beamlines and provide good performance with long-term reliability and ease of operation. Availability and advantages of such mirrors can make the mirror-first approach to high-heat-load beamline design an attractive alternative to monochromator-first beamlines in many circumstances

Crosswinds Effect on the Thermal Performance of Wet Cooling Towers Under Variable Operating Conditions

Science.gov (United States)

Chen, You Liang; Shi, Yong Feng; Hao, Jian Gang; Chang, Hao; Sun, Feng Zhong

2018-01-01

In order to quantitatively analyze the influence of the variable operating parameters on the cooling performance of natural draft wet cooling towers (NDWCTs), a hot model test system was set up with adjustable ambient temperature and humidity, circulating water flowrate and temperature. In order to apply the hot model test results to the real tower, the crosswind Froude number is defined. The results show that the crosswind has a negative effect on the thermal performance of the cooling tower, and there is a critical crosswind velocity corresponding to the lowest cooling efficiency. According to the crosswind Froude number similarity, when the ambient temperature decreases, or the circulating water flowrate and temperature increase, the cooling tower draft force will increase, and the critical crosswind velocity will increase correspondingly.

Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

Science.gov (United States)

Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

2016-06-01

In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

Experimental study on the thermal performance of a mechanical cooling tower with different drift eliminators

International Nuclear Information System (INIS)

Lucas, M.; Martinez, P.J.; Viedma, A.

2009-01-01

Cooling towers are equipment devices commonly used to dissipate heat from power generation units, water-cooled refrigeration, air conditioning and industrial processes. Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health hazards. It is common practice to fit drift eliminators to cooling towers in order to minimize water loss from the system. It is foreseeable that the characteristics of the installed drift eliminators, like their pressure drop, affect the thermal performance of the cooling tower. However, no references regarding this fact have been found in the reviewed bibliography. This paper studies the thermal performance of a forced draft counter-flow wet cooling tower fitted with different drift eliminators for a wide range of air and water mass flow rates. The data registered in the experimental set-up were employed to obtain correlations of the tower characteristic, which defines the cooling tower's thermal performance. The outlet water temperature predicted by these correlations was compared with the experimentally registered values obtaining a maximum difference of ±3%

Cooling improves the writing performance of patients with writer's cramp.

Science.gov (United States)

Pohl, Christoph; Happe, Jörg; Klockgether, Thomas

2002-11-01

Cooling of hand and forearm muscles by immersion in 15 degrees C cold water for 5 minutes improved the writing performance of patients with writer's cramp. Since abnormal processing of muscle spindle afferent discharges contributes to the pathology of writer's cramp, this effect might result from a reduction in muscle spindle activity by lowering muscle temperature. Cooling is a simple, cheap, and safe procedure, providing temporary relief for patients with writer's cramp. Copyright 2002 Movement Disorder Society

Performance assessment of earth pipe cooling system for low energy buildings in a subtropical climate

International Nuclear Information System (INIS)

Ahmed, S.F.; Khan, M.M.K.; Amanullah, M.T.O.; Rasul, M.G.; Hassan, N.M.S.

2015-01-01

Highlights: • Earth pipe cooling performance was investigated in a subtropical climate in Australia. • A thermal model was developed using Fluent to assess the cooling performance. • A temperature reduction of around 2 °C was found for the earth pipe cooling system. • Annual energy savings of maximum 866.54 kW (8.82%) was achieved for a 27.23 m"3 room. - Abstract: Energy consumption in heating and cooling around the world has been a major contributor to global warming. Hence, many studies have been aimed at finding new techniques to save and control energy through energy efficient measures. Most of this energy is used in residential, agricultural and commercial buildings. It is therefore important to adopt energy efficiency measures in these buildings through new technologies and novel building designs. These new building designs can be developed by employing various passive cooling systems. Earth pipe cooling is one of these which can assist to save energy without using any customary mechanical units. This paper investigates the earth pipe cooling performance in a hot humid subtropical climate of Rockhampton, Australia. A thermal model is developed using ANSYS Fluent for measuring its performance. Impacts of air velocity, air temperature, relative humidity and soil temperature on room cooling performance are also assessed. A temperature reduction of around 2 °C was found for the system. This temperature reduction contributed to an energy saving of a maximum of 866.54 kW (8.82%) per year for a 27.23 m"3 room.

Fuel performance and fission product behaviour in gas cooled reactors

International Nuclear Information System (INIS)

1997-11-01

The Co-ordinated Research Programme (CRP) on Validation of Predictive Methods for Fuel and Fission Product Behaviour was organized within the frame of the International Working Group on Gas Cooled Reactors. This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs), and supports the conduct of these activities. The objectives of this CRP were to review and document the status of the experimental data base and of the predictive methods for GCR fuel performance and fission product behaviour; and to verify and validate methodologies for the prediction of fuel performance and fission product transport

Thermodynamic performance optimization of a combined power/cooling cycle

International Nuclear Information System (INIS)

Pouraghaie, M.; Atashkari, K.; Besarati, S.M.; Nariman-zadeh, N.

2010-01-01

A combined thermal power and cooling cycle has already been proposed in which thermal energy is used to produce work and to generate a sub-ambient temperature stream that is suitable for cooling applications. The cycle uses ammonia-water mixture as working fluid and is a combination of a Rankine cycle and absorption cycle. The very high ammonia vapor concentration, exiting turbine under certain operating conditions, can provide power output as well as refrigeration. In this paper, the goal is to employ multi-objective algorithms for Pareto approach optimization of thermodynamic performance of the cycle. It has been carried out by varying the selected design variables, namely, turbine inlet pressure (P h ), superheater temperature (T superheat ) and condenser temperature (T condensor ). The important conflicting thermodynamic objective functions that have been considered in this study are turbine work (w T ), cooling capacity (q cool ) and thermal efficiency (η th ) of the cycle. It is shown that some interesting and important relationships among optimal objective functions and decision variables involved in the combined cycle can be discovered consequently. Such important relationships as useful optimal design principles would have not been obtained without the use of a multi-objective optimization approach.

Performance limits of direct cryogenically cooled silicon monochromators - experimental results at the APS

International Nuclear Information System (INIS)

Lee, W.-K.; Fernandez, P.; Mills, D.M.

2000-01-01

The successful use of cryogenically cooled silicon monochromators at third-generation synchrotron facilities is well documented. At the Advanced Photon Source (APS) it has been shown that, at 100 mA operation with the standard APS undulator A, the cryogenically cooled silicon monochromator performs very well with minimal (<2 arcsec) or no observable thermal distortions. However, to date there has not been any systematic experimental study on the performance limits of this approach. This paper presents experimental results on the performance limits of these directly cooled crystals. The results show that if the beam is limited to the size of the radiation central cone then, at the APS, the crystal will still perform well at twice the present 100 mA single 2.4 m-long 3.3 cm-period undulator heat load. However, the performance would degrade rapidly if a much larger incident white-beam size is utilized

Improving of the photovoltaic / thermal system performance using water cooling technique

International Nuclear Information System (INIS)

Hussien, Hashim A; Numan, Ali H; Abdulmunem, Abdulmunem R

2015-01-01

This work is devoted to improving the electrical efficiency by reducing the rate of thermal energy of a photovoltaic/thermal system (PV/T).This is achieved by design cooling technique which consists of a heat exchanger and water circulating pipes placed at PV module rear surface to solve the problem of the high heat stored inside the PV cells during the operation. An experimental rig is designed to investigate and evaluate PV module performance with the proposed cooling technique. This cooling technique is the first work in Iraq to dissipate the heat from PV module. The experimental results indicated that due to the heat loss by convection between water and the PV panel's upper surface, an increase of output power is achieved. It was found that without active cooling, the temperature of the PV module was high and solar cells could only achieve a conversion efficiency of about 8%. However, when the PV module was operated under active water cooling condition, the temperature was dropped from 76.8°C without cooling to 70.1°C with active cooling. This temperature dropping led to increase in the electrical efficiency of solar panel to 9.8% at optimum mass flow rate (0.2L/s) and thermal efficiency to (12.3%). (paper)

Proceedings: Cooling tower and advanced cooling systems conference

International Nuclear Information System (INIS)

1995-02-01

This Cooling Tower and Advanced Cooling Systems Conference was held August 30 through September 1, 1994, in St. Petersburg, Florida. The conference was sponsored by the Electric Power Research Institute (EPRI) and hosted by Florida Power Corporation to bring together utility representatives, manufacturers, researchers, and consultants. Nineteen technical papers were presented in four sessions. These sessions were devoted to the following topics: cooling tower upgrades and retrofits, cooling tower performance, cooling tower fouling, and dry and hybrid systems. On the final day, panel discussions addressed current issues in cooling tower operation and maintenance as well as research and technology needs for power plant cooling. More than 100 people attended the conference. This report contains the technical papers presented at the conference. Of the 19 papers, five concern cooling tower upgrades and retrofits, five to cooling tower performance, four discuss cooling tower fouling, and five describe dry and hybrid cooling systems. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database

3D Analysis of Cooling Performance with Loss of Offsite Power Using GOTHIC Code

International Nuclear Information System (INIS)

Oh, Kye Min; Heo, Gyun Young; Na, In Sik; Choi, Yu Jung

2010-01-01

GOTHIC code enables to analyze one-dimensional or multi-dimensional problems for evaluating the cooling performance of loss of offsite power. The conventional GOTHIC code analysis performs heat transfer between plant containment and the outside of the fan cooler tubes by modeling each of fan cooler part model and component cooling water inside tube each to analyze boiling probability. In this paper, we suggest a way which reduces the multi-procedure of the cooling performance with loss of offsite power or the heat transfer states with complex geometrical structure to a single-procedure and verify the applicability of the heat transfer differences from the containment atmosphere humidity changes by the multi-nodes which component cooling water of tube or air of Reactor Containment Fan Cooler in the containment, otherwise the component model uses only one node

Fuel performance and fission product behaviour in gas cooled reactors

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

The Co-ordinated Research Programme (CRP) on Validation of Predictive Methods for Fuel and Fission Product Behaviour was organized within the frame of the International Working Group on Gas Cooled Reactors. This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs), and supports the conduct of these activities. The objectives of this CRP were to review and document the status of the experimental data base and of the predictive methods for GCR fuel performance and fission product behaviour; and to verify and validate methodologies for the prediction of fuel performance and fission product transport. Refs, figs, tabs.

Cooling performance of a vertical ground-coupled heat pump system installed in a school building

Energy Technology Data Exchange (ETDEWEB)

Hwang, Yujin; Lee, Jae-Keun; Jeong, Young-Man; Koo, Kyung-Min [Department of Mechanical Engineering, Pusan National University, San 30, Jangjeon-Dong, Kumjung-Ku, Busan 609-735 (Korea); Lee, Dong-Hyuk; Kim, In-Kyu; Jin, Sim-Won [LG Electronics, 391-2 Gaeumjeong-dong, Changwon City, Gyeongnam (Korea); Kim, Soo H. [Department of Nanosystems and Nanoprocess Engineering, Pusan National University, San 30, Jangjeon-Dong, Kumjung-Ku, Busan 609-735 (Korea)

2009-03-15

This paper presents the cooling performance of a water-to-refrigerant type ground heat source heat pump system (GSHP) installed in a school building in Korea. The evaluation of the cooling performance has been conducted under the actual operation of GSHP system in the summer of year 2007. Ten heat pump units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. To analyze the cooling performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the cooling capacity and the input power were evaluated to determine the cooling performance of the GSHP system. The average cooling coefficient of performance (COP) and overall COP of the GSHP system were found to be {proportional_to}8.3 and {proportional_to}5.9 at 65% partial load condition, respectively. While the air source heat pump (ASHP) system, which has the same capacity with the GSHP system, was found to have the average COP of {proportional_to}3.9 and overall COP of {proportional_to}3.4, implying that the GSHP system is more efficient than the ASHP system due to its lower temperature of condenser. (author)

Influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle

International Nuclear Information System (INIS)

Sanjay; Singh, Onkar; Prasad, B.N.

2008-01-01

A comparative study of the influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle power plant is presented. Seven schemes involving air and steam as coolants under open and closed loop cooling techniques have been studied. The open loop incorporates the internal convection, film and transpiration cooling techniques. Closed loop cooling includes only internal convection cooling. It has been found that closed loop steam cooling offers more specific work and consequently gives higher value of plant efficiency of about 60%, whereas open loop transpiration steam cooling, open loop steam internal convection cooling, transpiration air cooling, film steam cooling, film air, and internal convection air cooling have been found to yield lower values of plant efficiency in decreasing order as compared to closed loop steam cooling

Cooled Beam Diagnostics on LEIR

CERN Document Server

Tranquille, G; Carli, C; Chanel, M; Prieto, V; Sautier, R; Tan, J

2008-01-01

Electron cooling is central in the preparation of dense bunches of lead beams for the LHC. Ion beam pulses from the LINAC3 are transformed into short highbrightness bunches using multi-turn injection, cooling and accumulation in the Low Energy Ion Ring, LEIR [1]. The cooling process must therefore be continuously monitored in order to guarantee that the lead ions have the required characteristics in terms of beam size and momentum spread. In LEIR a number of systems have been developed to perform these measurements. These include Schottky diagnostics, ionisation profile monitors and scrapers. Along with their associated acquisition and analysis software packages these instruments have proved to be invaluable for the optimisation of the electron cooler.

Development and validation of a full-range performance analysis model for a three-spool gas turbine with turbine cooling

International Nuclear Information System (INIS)

Song, Yin; Gu, Chun-wei; Ji, Xing-xing

2015-01-01

The performance analysis of a gas turbine is important for both its design and its operation. For modern gas turbines, the cooling flow introduces a noteworthy thermodynamic loss; thus, the determination of the cooling flow rate will clearly influence the accuracy of performance calculations. In this paper, a full-range performance analysis model is established for a three-spool gas turbine with an open-circuit convective blade cooling system. A hybrid turbine cooling model is embedded in the analysis to predict the amount of cooling air accurately and thus to remove the errors induced by the relatively arbitrary value of cooling air requirements in the previous research. The model is subsequently used to calculate the gas turbine performance; the calculation results are validated with detailed test data. Furthermore, multistage conjugate heat transfer analysis is performed for the turbine section. The results indicate that with the same coolant condition and flow rate as those in the performance analysis, the blade metal has been effectively cooled; in addition, the maximum temperature predicted by conjugate heat transfer analysis is close to the corresponding value in the cooling model. Hence, the present model provides an effective tool for analyzing the performance of a gas turbine with cooling. - Highlights: • We established a performance model for a gas turbine with convective cooling. • A hybrid turbine cooling model is embedded in the performance analysis. • The accuracy of the model is validated with detailed test data of the gas turbine. • Conjugate heat transfer analysis is performed for the turbine for verification

Design optimization of electric vehicle battery cooling plates for thermal performance

Science.gov (United States)

Jarrett, Anthony; Kim, Il Yong

The performance of high-energy battery cells utilized in electric vehicles (EVs) is greatly improved by adequate temperature control. An efficient thermal management system is also desirable to avoid diverting excessive power from the primary vehicle functions. In a battery cell stack, cooling can be provided by including cooling plates: thin metal fabrications which include one or more internal channels through which a coolant is pumped. Heat is conducted from the battery cells into the cooling plate, and transported away by the coolant. The operating characteristics of the cooling plate are determined in part by the geometry of the channel; its route, width, length, etc. In this study, a serpentine-channel cooling plate is modeled parametrically and its characteristics assessed using computational fluid dynamics (CFD). Objective functions of pressure drop, average temperature, and temperature uniformity are defined and numerical optimization is carried out by allowing the channel width and position to vary. The optimization results indicate that a single design can satisfy both pressure and average temperature objectives, but at the expense of temperature uniformity.

Evaluation of a Design Concept for the Combined Air-water Passive Cooling PAFS+

International Nuclear Information System (INIS)

Bae, Sung Won; Kwon, Taesoon

2014-01-01

The APR+ system provides the Passive Auxiliary Feed-water System (PAFS) for the passive cooling capability. However, the current design requirement for working time for the PAFS is about 8 hours only. Thus, current working time of PAFS can not meet the required 72 hours cooling capability for the long term SBO situation. To meet the 72 hours cooling, the pool capacity should be almost 3∼4 times larger than that of current water cooling tank. In order to continue the PAFS operation for 72 hours, a new passive air-water combined cooling system is proposed. This paper provides the feasibility study on the combined passive air-water cooling system. Figure 1 and 2 show the conceptual difference of the PAFS and combined passive air-water cooling system, respectively. Simple performance evaluation of the passive air cooling heat exchanger has been conducted by the MARS calculation. For the postulated FLB scenario, 4800 heat exchanger tubes and 5 m/s air velocity are not sufficient to sustain the PCCT pool level for 72 hour cooling. Further works on the system design and performance enhancing plan are required to fulfill the 72 hours long term passive cooling

Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension

OpenAIRE

Mushtaq Ismael Hasan

2017-01-01

In this paper the electrical distribution transformer has been studied numerically and the effect of outside temperature on its cooling performance has been investigated. The temperature range studied covers the hot climate regions. 250 KVA distribution transformer is chosen as a study model. A novel cooling fluid is proposed to improve the cooling performance of this transformer, transformer oil-based microencapsulated phase change materials suspension is used with volume concentration (5–25...

Evaluation of the performance of combined cooling, heating, and power systems with dual power generation units

International Nuclear Information System (INIS)

Knizley, Alta A.; Mago, Pedro J.; Smith, Amanda D.

2014-01-01

The benefits of using a combined cooling, heating, and power system with dual power generation units (D-CCHP) is examined in nine different U.S. locations. One power generation unit (PGU) is operated at base load while the other is operated following the electric load. The waste heat from both PGUs is used for heating and for cooling via an absorption chiller. The D-CCHP configuration is studied for a restaurant benchmark building, and its performance is quantified in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Cost spark spread, PEC spark spread, and CDE spark spread are examined as performance indicators for the D-CCHP system. D-CCHP system performance correlates well with spark spreads, with higher spark spreads signifying greater savings through implementation of a D-CCHP system. A new parameter, thermal difference, is introduced to investigate the relative performance of a D-CCHP system compared to a dual PGU combined heat and power system (D-CHP). Thermal difference, together with spark spread, can explain the variation in savings of a D-CCHP system over a D-CHP system for each location. The effect of carbon credits on operational cost savings with respect to the reference case is shown for selected locations. - Highlights: • We investigate benefits from using combined cooling, heating, and power systems. • A dual power generation unit configuration is considered for CCHP and CHP. • Spark spreads for cost, energy, and emissions correlate with potential savings. • Thermal difference parameter helps to explain variations in potential savings. • Carbon credits may increase cost savings where emissions savings are possible

Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring

OpenAIRE

Zuo, Zheng; Hu, Yu; Li, Qingbin; Zhang, Liyuan

2014-01-01

Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting ...

Effect of Thermoelectric Cooling (TEC module and the water flow heatsink on Photovoltaic (PV panel performance

Directory of Open Access Journals (Sweden)

Amelia A.R.

2017-01-01

Full Text Available Photovoltaic (PV panel suffers in low conversion efficiency of the output performance affected by the elevated operating temperature of the PV panel. It is important to keep the PV panel to operate at low temperature. To address this issue, this paper proposes the cooling system using thermoelectric cooling (TEC and water block heatsink for enhancing the PV panel output performance. These both types cooling system were designed located on the back side of the PV panel to cool down the operating temperature of the PV panel. To evaluate the function for the existing cooling systems, the experiment was subsequently performed for PV panel without and with different design of the cooling system in outdoor weather conditions. By comparing the experimental results, it is concluded that by the hybrid cooling system which combining TEC module and the water block heatsink could improve the output performance of the PV panel. By the reduction temperature of the PV panel by 16.04 %, the average output power of the PV panel has been boosted up from 8.59 W to 9.03 W. In short, the output power of the PV panel was enhanced by the reduction of the operating temperature of the PV panel.

Effect of Thermoelectric Cooling (TEC) module and the water flow heatsink on Photovoltaic (PV) panel performance

Science.gov (United States)

Amelia, A. R.; Jusoh, MA; Shamira Idris, Ida

2017-11-01

Photovoltaic (PV) panel suffers in low conversion efficiency of the output performance affected by the elevated operating temperature of the PV panel. It is important to keep the PV panel to operate at low temperature. To address this issue, this paper proposes the cooling system using thermoelectric cooling (TEC) and water block heatsink for enhancing the PV panel output performance. These both types cooling system were designed located on the back side of the PV panel to cool down the operating temperature of the PV panel. To evaluate the function for the existing cooling systems, the experiment was subsequently performed for PV panel without and with different design of the cooling system in outdoor weather conditions. By comparing the experimental results, it is concluded that by the hybrid cooling system which combining TEC module and the water block heatsink could improve the output performance of the PV panel. By the reduction temperature of the PV panel by 16.04 %, the average output power of the PV panel has been boosted up from 8.59 W to 9.03 W. In short, the output power of the PV panel was enhanced by the reduction of the operating temperature of the PV panel.

Coarse Grid Modeling of Turbine Film Cooling Flows Using Volumetric Source Terms

Science.gov (United States)

Heidmann, James D.; Hunter, Scott D.

2001-01-01

The recent trend in numerical modeling of turbine film cooling flows has been toward higher fidelity grids and more complex geometries. This trend has been enabled by the rapid increase in computing power available to researchers. However, the turbine design community requires fast turnaround time in its design computations, rendering these comprehensive simulations ineffective in the design cycle. The present study describes a methodology for implementing a volumetric source term distribution in a coarse grid calculation that can model the small-scale and three-dimensional effects present in turbine film cooling flows. This model could be implemented in turbine design codes or in multistage turbomachinery codes such as APNASA, where the computational grid size may be larger than the film hole size. Detailed computations of a single row of 35 deg round holes on a flat plate have been obtained for blowing ratios of 0.5, 0.8, and 1.0, and density ratios of 1.0 and 2.0 using a multiblock grid system to resolve the flows on both sides of the plate as well as inside the hole itself. These detailed flow fields were spatially averaged to generate a field of volumetric source terms for each conservative flow variable. Solutions were also obtained using three coarse grids having streamwise and spanwise grid spacings of 3d, 1d, and d/3. These coarse grid solutions used the integrated hole exit mass, momentum, energy, and turbulence quantities from the detailed solutions as volumetric source terms. It is shown that a uniform source term addition over a distance from the wall on the order of the hole diameter is able to predict adiabatic film effectiveness better than a near-wall source term model, while strictly enforcing correct values of integrated boundary layer quantities.

Performance Analyses of Counter-Flow Closed Wet Cooling Towers Based on a Simplified Calculation Method

Directory of Open Access Journals (Sweden)

Xiaoqing Wei

2017-02-01

Full Text Available As one of the most widely used units in water cooling systems, the closed wet cooling towers (CWCTs have two typical counter-flow constructions, in which the spray water flows from the top to the bottom, and the moist air and cooling water flow in the opposite direction vertically (parallel or horizontally (cross, respectively. This study aims to present a simplified calculation method for conveniently and accurately analyzing the thermal performance of the two types of counter-flow CWCTs, viz. the parallel counter-flow CWCT (PCFCWCT and the cross counter-flow CWCT (CCFCWCT. A simplified cooling capacity model that just includes two characteristic parameters is developed. The Levenberg–Marquardt method is employed to determine the model parameters by curve fitting of experimental data. Based on the proposed model, the predicted outlet temperatures of the process water are compared with the measurements of a PCFCWCT and a CCFCWCT, respectively, reported in the literature. The results indicate that the predicted values agree well with the experimental data in previous studies. The maximum absolute errors in predicting the process water outlet temperatures are 0.20 and 0.24 °C for the PCFCWCT and CCFCWCT, respectively. These results indicate that the simplified method is reliable for performance prediction of counter-flow CWCTs. Although the flow patterns of the two towers are different, the variation trends of thermal performance are similar to each other under various operating conditions. The inlet air wet-bulb temperature, inlet cooling water temperature, air flow rate, and cooling water flow rate are crucial for determining the cooling capacity of a counter-flow CWCT, while the cooling tower effectiveness is mainly determined by the flow rates of air and cooling water. Compared with the CCFCWCT, the PCFCWCT is much more applicable in a large-scale cooling water system, and the superiority would be amplified when the scale of water

Performance analysis of phase-change material storage unit for both heating and cooling of buildings

Science.gov (United States)

Waqas, Adeel; Ali, Majid; Ud Din, Zia

2017-04-01

Utilisation of solar energy and the night ambient (cool) temperatures are the passive ways of heating and cooling of buildings. Intermittent and time-dependent nature of these sources makes thermal energy storage vital for efficient and continuous operation of these heating and cooling techniques. Latent heat thermal energy storage by phase-change materials (PCMs) is preferred over other storage techniques due to its high-energy storage density and isothermal storage process. The current study was aimed to evaluate the performance of the air-based PCM storage unit utilising solar energy and cool ambient night temperatures for comfort heating and cooling of a building in dry-cold and dry-hot climates. The performance of the studied PCM storage unit was maximised when the melting point of the PCM was ∼29°C in summer and 21°C during winter season. The appropriate melting point was ∼27.5°C for all-the-year-round performance. At lower melting points than 27.5°C, declination in the cooling capacity of the storage unit was more profound as compared to the improvement in the heating capacity. Also, it was concluded that the melting point of the PCM that provided maximum cooling during summer season could be used for winter heating also but not vice versa.

Performance Evaluation of an In-Wheel Motor Cooling System in an Electric Vehicle/Hybrid Electric Vehicle

Directory of Open Access Journals (Sweden)

Dong Hyun Lim

2014-02-01

Full Text Available High power and miniaturization of motors in an in-wheel drive system, which is installed inside the wheels of a vehicle, are required for directly driving the wheels. In addition, an efficient cooling system is required to ensure high driving performance and durability. This study experimentally evaluated the heat dissipation performance of a 35-kW-class large-capacity in-wheel motor equipped with an internal-circulation-type oil-cooling system that exhibits high cooling performance and can be easily miniaturized to this motor. Temperatures of the coil and stator core of cooling systems with and without a radiator were measured in real time under in-wheel motor driving conditions. It was found that operating the cooling system at a continuous-rating maximum speed without the radiator was difficult. We confirmed that under continuous-rating base speed and continuous-rating maximum speed driving conditions, the cooling system with the radiator showed thermally stable operation. Furthermore, under maximum-rating base speed and maximum-rating maximum speed driving conditions, the cooling system with the radiator provided additional driving times of approximately 22 s and 2 s, respectively.

High-temperature gas-cooled reactor (HTGR): long term program plan

International Nuclear Information System (INIS)

1980-01-01

The FY 1980 effort was to investigate four technology options identified by program participants as potentially viable candidates for near-term demonstration: the Gas Turbine system (HTGR-GT), reflecting its perceived compatibility with the dry-cooling market, two systems addressing the process heat market, the Reforming (HTGR-R) and Steam Cycle (HTGR-SC) systems, and a more developmental reactor system, The Nuclear Heat Source Demonstration Reactor (NHSDR), which was to serve as a basis for both the HTGR-GT and HTGR-R systems as well as the further potential for developing advanced applications such as steam-coal gasification and water splitting

Cooling tower water ozonation at Southern University

International Nuclear Information System (INIS)

Chen, C.C.; Knecht, A.T.; Trahan, D.B.; Yaghi, H.M.; Jackson, G.H.; Coppenger, G.D.

1990-01-01

Cooling-tower water is a critical utility for many industries. In the past, inexpensive water coupled with moderate regulation of discharge water led to the neglect of the cooling tower as an energy resource. Now, with the increased cost of chemical treatment and tough EPA rules and regulations, this situation is rapidly changing. The operator of the DOE Y-12 Plant in Oak Ridge as well as many other industries are forced to develop an alternate method of water treatment. The cooling tower is one of the major elements in large energy systems. The savings accrued from a well engineered cooling tower can be a significant part of the overall energy conservation plan. During a short-term ozonation study between 1987-1988, the Y-12 Plant has been successful in eliminating the need for cooling tower treatment chemicals. However, the long-term impact was not available. Since April 1988, the ozone cooling water treatment study at the Y-12 Plant has been moved to the site at Southern University in Baton Rouge, Louisiana. The purpose of this continued study is to determine whether the use of ozonation on cooling towers is practical from an economic, technical and environmental standpoint. This paper discusses system design, operating parameter and performance testing of the ozonation system at Southern University

A temperature rise equation for predicting environmental impact and performance of cooling ponds

Energy Technology Data Exchange (ETDEWEB)

Serag-Eldin, M.A. [American Univ. in Cairo, Cairo (Egypt). Dept. of Mechanical Engineering

2009-07-01

Cooling ponds are used to cool the condenser water used in large central air-conditioning systems. However, larger cooling loads can often increase pond surface evaporation rates. A temperature-rise energy equation was developed to predict temperature rises in cooling ponds subjected to heating loads. The equation was designed to reduce the need for detailed meteorological data as well as to determine the required surface area and depth of the pond for any given design criteria. Energy equations in the presence and absence of cooling loads were subtracted from each other to determine increases in pond temperature resulting from the cooling load. The energy equations include solar radiation, radiation exchange with sky and surroundings, heat convection from the surface, evaporative cooling, heat conducted to the walls, and rate of change of water temperature. Results of the study suggested that the environmental impact and performance of the cooling pond is a function of temperature only. It was concluded that with the aid of the calculated flow field and temperature distribution, the method can be used to position sprays in order to produce near-uniform pond temperatures. 10 refs., 12 figs.

Experimental investigation of cooling performance of a novel HVAC system combining natural ventilation with diffuse ceiling inlet and TABS

DEFF Research Database (Denmark)

Yu, Tao; Heiselberg, Per Kvols; Lei, Bo

2015-01-01

Highlights •An experimental investigation of cooling performance of a combined HVAC system is carried out. •Cooling performance of TABS with and without the influence of diffuse ceiling is analyzed. •Radiant and convective heat transfer coefficients of TABS cooling are studied. •Cooling components...

Coupling model and solving approach for performance evaluation of natural draft counter-flow wet cooling towers

Directory of Open Access Journals (Sweden)

Wang Wei

2016-01-01

Full Text Available When searching for the optimum condenser cooling water flow in a thermal power plant with natural draft cooling towers, it is essential to evaluate the outlet water temperature of cooling towers when the cooling water flow and inlet water temperature change. However, the air outlet temperature and tower draft or inlet air velocity are strongly coupled for natural draft cooling towers. Traditional methods, such as trial and error method, graphic method and iterative methods are not simple and efficient enough to be used for plant practice. In this paper, we combine Merkel equation with draft equation, and develop the coupled description for performance evaluation of natural draft cooling towers. This model contains two inputs: the cooling water flow, the inlet cooling water temperature and two outputs: the outlet water temperature, the inlet air velocity, equivalent to tower draft. In this model, we furthermore put forward a soft-sensing algorithm to calculate the total drag coefficient instead of empirical correlations. Finally, we design an iterative approach to solve this coupling model, and illustrate three cases to prove that the coupling model and solving approach proposed in our paper are effective for cooling tower performance evaluation.

Evaluation of long-term post-accident core cooling of Three Mile Island Unit 2

Energy Technology Data Exchange (ETDEWEB)

None

1979-04-15

On the basis of current understanding of the accident scenario and available data, the staff reports here on its evaluation of the condition of the core and the core flow resistance as it might affect ability to cool the core by natural circulation. The natural circulation cooling capability of TMI-2 for the estimated core flow resistance and a variety of other conditions is evaluated and a comparison of the Base Case and off-nominal plant configurations is presented. The potential for and effects of natural convection core cooling are addressed, and the staff recommendations for reactor performance acceptance criteria upon initiation of natural convection are presented.

Performance and economic enhancement of cogeneration gas turbines through compressor inlet air cooling

Science.gov (United States)

Delucia, M.; Bronconi, R.; Carnevale, E.

1994-04-01

Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine's power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.

Effect of Cooling Units on the Performance of an Automotive Exhaust-Based Thermoelectric Generator

Science.gov (United States)

Su, C. Q.; Zhu, D. C.; Deng, Y. D.; Wang, Y. P.; Liu, X.

2017-05-01

Currently, automotive exhaust-based thermoelectric generators (AETEGs) are a hot topic in energy recovery. In order to investigate the influence of coolant flow rate, coolant flow direction and cooling unit arrangement in the AETEG, a thermoelectric generator (TEG) model and a related test bench are constructed. Water cooling is adopted in this study. Due to the non-uniformity of the surface temperature of the heat source, the coolant flow direction would affect the output performance of the TEG. Changing the volumetric flow rate of coolant can increase the output power of multi-modules connected in series or/and parallel as it can improve the temperature uniformity of the cooling unit. Since the temperature uniformity of the cooling unit has a strong influence on the output power, two cooling units are connected in series or parallel to research the effect of cooling unit arrangements on the maximum output power of the TEG. Experimental and theoretical analyses reveal that the net output power is generally higher with cooling units connected in parallel than cooling units connected in series in the cooling system with two cooling units.

Improving the performance of power-limited transverse stochastic cooling systems

International Nuclear Information System (INIS)

Goldberg, D.A.; Lambertson, G.R.

1989-08-01

We present the formulas relevant to the behavior of (transverse) stochastic cooling systems which operate under the not uncommon condition that performance is limited by available output power, and contrast the operation of such systems with non-power-limited ones. In particular, we show that for power-limited systems, the two most effective improvements are the use of pickups/kickers which operate in both planes simultaneously and/or plunging of the cooling system electrodes, and present an example where increasing bandwidth is counter-productive. We apply our results to the proposed upgrade of the Fermilab bar p source. 4 refs., 1 fig., 2 tabs

Development of a Long Term Cooling Analysis Methodology Using Rappel

International Nuclear Information System (INIS)

Lee, S. I.; Jeong, J. H.; Ban, C. H.; Oh, S. J.

2012-01-01

Since the revision of the 10CFR50.46 in 1988, which allowed BE (Best-Estimate) method in analyzing the safety performance of a nuclear power plant, safety analysis methodologies have been changed continuously from conservative EM (Evaluation Model) approaches to BE ones. In this context, LSC (Long-Term core Cooling) methodologies have been reviewed by the regulatory bodies of USA and Korea. Some non-conservatism and improperness of the old methodology have been identified, and as a result, USNRC suspended the approval of CENPD-254-P-A which is the old LSC methodology for CE-designed NPPs. Regulatory bodies requested to remove the non-conservatisms and to reflect system transient behaviors in all the LSC methodologies used. In the present study, a new LSC methodology using RELAP5 is developed. RELAP5 and a newly developed code, BACON (Boric Acid Concentration Of Nuclear power plant) are used to calculate the transient behavior of the system and the boric acid concentration, respectively. Full range of break spectrum is considered and the applicability is confirmed through plant demonstration calculations. The result shows a good comparison with the old-fashioned ones, therefore, the methodology could be applied with no significant changes of current LSC plans

Effects of Cooling on the Reproductive Performance of Gilts ...

African Journals Online (AJOL)

PROF HORSFALL

with 3 systems of cooling, namely Wallow Cooling (WC), Sprinkler Cooling (SC) ... piggery would help to increase litter size, improve feed intake per litter and ... temperature on the productivity of livestock, experts ... Cooling (SC) and Zero Cooling (ZC) applied to sows ... consumed for body maintenance and growth by gilts.

[Effectiveness of scalp cooling in chemotherapy].

Science.gov (United States)

Poder, Thomas G; He, Jie; Lemieux, Renald

2011-10-01

The main objectives of this literature review are to determine if scalp cooling is efficient and safe, if there are side effects and if the patients' quality of life improves. In terms of effectiveness, scalp cooling seems to get good performance in its aim to prevent hair loss in patients receiving chemotherapy. The weighted average results of all identified studies indicate that this technology allows for 63.5% of patients to have a good preservation of their hair. In studies with a group of control, the weighted rates of good preservation of the hair are 50.6% with scalp cooling and 16.3% without. From the standpoint of safety technology, the main risk is that of scalp metastases. However, no study has successfully demonstrated a statistically significant difference between groups of patients receiving chemotherapy with or without scalp cooling.

Performance comparison of liquid metal and gas cooled ATW system point designs

International Nuclear Information System (INIS)

Yang, W.S.; Taiwo, T.A.; Hill, R.N.; Khalil, H.S.; Wade, D.C.

2001-01-01

As part of the Advanced Accelerator Application (AAA) program in the U.S., preliminary design studies have been performed at Argonne National Laboratory (ANL) and Los Alamos National Laboratory (LANL) to define and compare candidate Accelerator Transmutation of Waste (ATW) systems. The studies at ANL have focused primarily on the transmutation blanket component of the overall system. Lead-bismuth eutectic (LBE), sodium, and gas cooled systems are among the blanket technology options currently under consideration. This paper summarizes the results from neutronics trade studies performed at ANL. Core designs have been developed for LBE and sodium cooled 840 MWt fast spectrum accelerator driven systems employing re-cycle. Additionally, neutronics analyses have been performed for a helium-cooled 600 MWt hybrid thermal and fast spectrum system proposed by General Atomics (GA), which is operated in the critical mode for three cycles and in a subcritical accelerator driven mode for a subsequent single cycle. For these three point designs, isotopic inventories, consumption rates, and annual burnup rates are compared. The mass flows and the ultimate loss of transuranic (TRU) isotopes to the waste stream per unit of heat generated during transmutation are also compared on a consistent basis. (author)

Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension

Directory of Open Access Journals (Sweden)

Mushtaq Ismael Hasan

2017-04-01

Full Text Available In this paper the electrical distribution transformer has been studied numerically and the effect of outside temperature on its cooling performance has been investigated. The temperature range studied covers the hot climate regions. 250 KVA distribution transformer is chosen as a study model. A novel cooling fluid is proposed to improve the cooling performance of this transformer, transformer oil-based microencapsulated phase change materials suspension is used with volume concentration (5–25% as a cooling fluid instead of pure transformer oil. Paraffin wax is used as a phase change material to make the suspension, in addition to the ability of heat absorption due to melting, the paraffin wax considered as a good electrical insulator. Results obtained show that, using of MEPCM suspension instead of pure transformer oil lead to improve the cooling performance of transformer by reducing its temperature and as a consequence increasing its protection against the breakdown. The melting fraction increased with increasing outside temperature up to certain temperature after which the melting fraction reach maximum constant value (MF = 1 which indicate that, the choosing of PCM depend on the environment in which the transformer is used.

Performing coolness: smoking refusal and adolescent identities.

Science.gov (United States)

Plumridge, E W; Fitzgerald, L J; Abel, G M

2002-04-01

The implications of smoking refusal for personal identity style were studied through conversations in six small focus groups or dyads of 13- and 14-year-old non-smokers from an urban New Zealand secondary school. The approach to analyzing their talk was informed by notions of 'performativity' and 'social space' to focus on the connections between identity and social relations. Smoking emerged as a key signifier of power and status. It was salient at both top and bottom ends of the social hierarchy depending upon the competence displayed in smoking as part of a larger ensemble of personal deportment and behavior. Being a non-smoker therefore inevitably carried connotations of being 'average' or 'in the middle', presenting non-smoking adolescents with the problem of accrediting themselves against superior 'smoker cool' groups. A discourse analytic approach was used to examine the resources and strategies participants brought to bear on this 'problem', which was then seen to be solved differently by boys and girls. Boys could establish alternatives to 'smoker cool' through physical activity, girls had little recourse but to accept their inferior status. The implications of this for health education and promotion are discussed.

Neck-cooling improves repeated sprint performance in the heat

Directory of Open Access Journals (Sweden)

Caroline eSunderland

2015-11-01

Full Text Available The present study evaluated the effect of neck-cooling during exercise on repeated sprint ability in a hot environment. Seven team-sport playing males completed two experimental trials involving repeated sprint exercise (5 x 6 s before and after two 45 min bouts of a football specific intermittent treadmill protocol in the heat (33.0  0.2 ºC; 53 ± 2% relative humidity. Participants wore a neck-cooling collar in one of the trials (CC. Mean power output and peak power output declined over time in both trials but were higher in CC (540 ± 99 v 507 ± 122W, d = 0.32; 719 ± 158 v 680 ± 182 W, d = 0.24 respectively. The improved power output was particularly pronounced (d = 0.51 – 0.88 after the 2nd 45 min bout but the CC had no effect on % fatigue. The collar lowered neck temperature and the thermal sensation of the neck (P 0.05. There were no trial differences but interaction effects were demonstrated for prolactin concentration and rating of perceived exertion (RPE. Prolactin concentration was initially higher in the collar cold trial and then was lower from 45 minutes onwards (interaction trial x time P=0.04. RPE was lower during the football intermittent treadmill protocol in the collar cold trial (interaction trial x time P = 0.01. Neck-cooling during exercise improves repeated sprint performance in a hot environment without altering physiological or neuroendocrinological responses. RPE is reduced and may partially explain the performance improvement.

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

Numerical simulation of the effects of hanging sound absorbers on TABS cooling performance

DEFF Research Database (Denmark)

Rage, Nils; Kazanci, Ongun Berk; Olesen, Bjarne W.

2016-01-01

simulating a two-person office of 20 m2, with a typical cooling load of 42 W/m2. The results show that covering 60% of the ceiling surface with sound absorbers hanging at 300 mm from the ceiling active deck is expected to reduce the cooling capacity coefficient of TABS by 15.8%. This drops to 25......Recently there has been a considerable increase in the use of Thermally-Active Building Systems (TABS) in Europe as an energy-efficient and economical cooling and heating solution for buildings. However, this widespread solution requires large uncovered hard surfaces indoors, which can lead...... to a degradation of the room acoustic comfort. Therefore, challenges arise when this system has to be combined with acoustic requirements. Soffit-hanging sound absorbers embody a promising solution. This study focuses on quantifying their impact on the cooling performance of TABS, assessed by means of the cooling...

Effect of Target Configuration on the Neutronic Performance of the Gas-Cooled ADS

CERN Document Server

Biss, K; Shetty, N; Nabbi, R

2013-01-01

With the utilization of nuclear energy transuranic elements like Pu, Am and Cm are produced causing high, long term radioactivity and radio toxicity, respectively. To reduce the radiological impact on the environment and to the repository Partitioning and Transmutation is considered as an efficient way. In this respect comprehensive research works are performed at different research institutes worldwide. The results show that the transmutation of TRU is achieved with fast neutrons due to the higher fission probability. Based on Accelerator Driven Systems (ADS) those neutrons are used in a particular system, in which mainly liquid metal eutectic (lead bismuth) is used as coolant. The neutronic performance of an ADS system based on gas cooling was studied in this work by using the simulation tool MCNPX. The usage of the Monte-Carlo method in MCNPX allows the simulation of the physical processes in a 3D-model of the core. In dependence of the spallation target material and design several parameters like the mult...

Condensation heat transfer coefficient of air-cooled condensing heat exchanger of emergency cooldown tank in long-term passive cooling system

International Nuclear Information System (INIS)

Huh, Seon Jeong; Lee, Hee Joon; Moon, Joo Hyung; Bae, Youngmin; Kim, Young In

2017-01-01

For the design purpose of air-cooled condensing heat exchanger of emergency cooldown tank, average condensation heat transfer coefficient inside a circular tube was reduced by a thermal sizing program using the experimental data of Kim et al. It was compared to the existing condensation heat transfer correlations. Moreover, a sensitivity analysis of both inside condensation and outside air natural convection correlations was performed. Although condensation heat transfer did not play a great role to design over 10 3 W/m 2 /K, the improved Shah's correlation gives the best prediction for the design. Consequently, air natural convection coefficient significantly affects the design of air-cooled condensing heat exchanger. (author)

Performance study of ejector cooling cycle at critical mode under superheated primary flow

International Nuclear Information System (INIS)

Tashtoush, Bourhan; Alshare, Aiman; Al-Rifai, Saja

2015-01-01

Highlights: • The ECC is modeled using EES Software and it is validated with published data. • Detailed analysis of the ECC with different refrigerants is conducted. • The constant pressure mixing is better than constant area mixing ejectors. • R134a is the selected refrigerant for the best cooling cycle performance. • The superheated primary flow at critical mode is achieved with EJ2 ejector used. - Abstract: In this work the performance of the ejector cooling cycle is investigated at critical mode, where, the effects of ejector geometry, refrigerant type, and operating condition are studied. The ejector cooling cycle is modeled with EES Software. The mass, momentum, and energy conservation principles are applied to the secondary and primary flows to investigate the performance of the ejector cooling cycle under superheated primary flow. The refrigerant R134 a is selected based on the merit of its environmental and performance characteristics. The primary working fluid in the refrigeration cycle is maintained at superheated conditions for optimal ejector performance. The solar generator temperature ranges are 80–100 °C. The operating temperature of evaporator range is 8–12 °C and the optimal condensation temperature is in the range of 28–40 °C. It is found that constant-pressure mixing ejector generates higher backpressure than constant-area mixing ejector for the same entrainment ratio and COP. The type of ejector is selected based on the performance criteria of the critical backpressure and choking condition of the primary flow, the so called EJ2 type ejector meets the criteria. The COP is found to be in the range of 0.59–0.67 at condenser backpressure of 24 bar due to higher critical condenser pressure and higher generator temperature

Isolated effects of peripheral arm and central body cooling on arm performance.

Science.gov (United States)

Giesbrecht, G G; Wu, M P; White, M D; Johnston, C E; Bristow, G K

1995-10-01

Whole body cooling impairs manual arm performance. The independent contributions of local (peripheral) and/or whole body (central) cooling are not known. Therefore, a protocol was developed in which the arm and the rest of the body could be independently cooled. Biceps temperature (Tmus), at a depth of 20 mm, and esophageal temperature (Tes) were measured. Six subjects were immersed to the clavicles in a tank (body tank) of water under 3 conditions: 1) cold body-cold arm (CB-CA); 2) warm body-cold arm (WB-CA); and 3) cold body-warm arm (CB-WA). In the latter two conditions, subjects placed their dominant arm in a separate (arm) tank. Water temperature (Tw) in each tank was independently controlled. In conditions requiring cold body and/or cold arm, Tw in the appropriate tanks was 8 degrees C. In conditions requiring warm body and/or warm arm, Tw in the appropriate tanks was adjusted between 29 and 38 degrees C to maintain body/arm temperature at baseline values. A battery of 6 tests, requiring fine or gross motor movements, were performed immediately before immersion and after 15, 45, and 70 minutes of immersion. In CB-CA, Tes decreased from an average of 37.2 to 35.6 degrees C and Tmus decreased from 34.6 to 22.0 degrees C. In WB-CA, Tmus decreased to 18.1 degrees C (Tes = 37.1 degrees C), and in CB-WA, Tes decreased to 35.8 degrees C (Tmus = 34.5 degrees C). By the end of immersion, there were significant decrements (43-85%) in the performance of all tests in CB-CA and WB-CA (p body and/or the arm elicits large decrements in finger, hand and arm performance. The decrements are due almost entirely to the local effects of arm tissue cooling.

Performance evaluation of a stack cooling system using CO{sub 2} air conditioner in fuel cell vehicles

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Chul; Won, Jong Phil [Thermal Management Research Center, Korea Automotive Technology Institute, Chungnam 330-912 (Korea); Park, Yong Sun; Lim, Tae Won [Corporate Research and Development Division, Hyundai-Kia Motors, Gyeonggi 449-912 (Korea); Kim, Min Soo [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)

2009-01-15

A relation between the heat release from a fuel cell stack and an air conditioning system's performance was investigated. The air conditioning system installed in a fuel cell vehicle can be used for stack cooling when additional stack heat release is required over a fixed radiator capacity during high vehicle power generation. This study investigated the performance of a stack cooling system using CO{sub 2} air conditioner at various operating conditions. Also, the heat releasing effectiveness and mutual interference were analyzed and compared with those for the conventional radiator cooling system with/without cabin cooling. When the radiator coolant inlet temperature and flow rate were 65 C and 80 L/min, respectively, for the outdoor air inlet speed of 5 m/s, the heat release of the stack cooling system with the aid of CO{sub 2} air conditioner increased up to 36% more than that of the conventional radiator cooling system with cabin cooling. Furthermore, this increased by 7% versus the case without cabin cooling. (author)

Energy and Exergy Analysis for Improving the Energy Performance of Air-Cooled Liquid Chillers by Different Condensing-Coil Configurations

Directory of Open Access Journals (Sweden)

Tzong-Shing Lee

2012-03-01

Full Text Available This study constructed a parameter analysis for improving the energy performance of air-cooled water chillers by altering the angle configuration of the condenser coils. The mathematical models for energy and exergy analyses of the individual components and overall system of air-cooled water chillers are presented. This study investigated the potential enhancement of performance efficiency in air-cooled chillers and the energy conversion efficiency of each component, in order to determine how the angle configuration of condenser coils influences chiller performance. This study found that the overall performance of an air-cooled chiller could be improved by approximately 3.4%, and the total irreversibility could be reduced by approximately 2.7%. With each 1% increase in average wind speed over the condenser coils, the overall performance of an air‑cooled chiller was found to be enhanced by approximately 0.43%, and its total irreversibility was reduced by approximately 0.35%. The results of this study can be effectively applied to air-cooled condenser units, and can provide an important basis of reference for developing and enhancing the energy efficiency of air-cooled chillers.

Optimum dry-cooling sub-systems for a solar air conditioner

Science.gov (United States)

Chen, J. L. S.; Namkoong, D.

1978-01-01

Dry-cooling sub-systems for residential solar powered Rankine compression air conditioners were economically optimized and compared with the cost of a wet cooling tower. Results in terms of yearly incremental busbar cost due to the use of dry-cooling were presented for Philadelphia and Miami. With input data corresponding to local weather, energy rate and capital costs, condenser surface designs and performance, the computerized optimization program yields design specifications of the sub-system which has the lowest annual incremental cost.

SBLOCA analysis to set-up the long term cooling plan for the SMART-P

International Nuclear Information System (INIS)

Bae, K. H.; Lee, G. H.; Lee, J.; Kim, H. C.; Zee, S. Q.

2005-01-01

SMART-P is a pilot plant of the SMART (System-integrated Modular Advanced ReacTor) producing a maximum thermal power of 65.5 MW. Different from the conventional loop type PWRs, the SMART-P contains the reactor coolant and the major primary circuit components, such as the core, two Main Coolant Pumps (MCPs), twelve SG cassettes, and the PZR in a single Reactor Pressure Vessel (RPV). Due to this integral arrangement of the primary system, only the small branch line break or leak through a component penetrating the RPV is postulated. Also, the reactor building spray system is not adopted in the SMART-P design. Thus, the energy released into the reactor building is removed by the condensation on the surface of the passive heat sinks and is transferred to the reactor building sump. After a Small Break Loss of Coolant Accident (SBLOCA), the Reactor Coolant System (RCS) pressure decreases rapidly. When the PZR pressure reaches the low-pressure reactor trip setpoint, the control rods drop into the core and decrease the core power rapidly. Simultaneously with the reactor trip, the MCPs start to coastdown, the main steam and feedwater isolation valves are closed, and the Passive Residual Heat Removal System (PRHRS) is connected to the secondary side of the SG. As the RCS pressure decreases to the safety injection actuation setpoint, a safety injection pump starts to deliver the cold coolant from the RWST to the RPV. Afterwards, the Safety Injection System (SIS) and PRHRS cool the RCS to the hot shutdown condition (200 .deg. C). When the RWST level reaches a low-level setpoint, Recirculation Actuation Signal (RAS) is generated, which transfers the suction of the SIS from the RWST to the reactor building sump. Long Term Cooling (LTC) operation after a SBLOCA is continued until the plant reaches a safe temperature level by using the SIS and PRHRS. In the SMART-P, the normal Shutdown Cooling System (SCS) is designed to cool the RCS from the hot shutdown condition (200 .deg. C

Modeling and performance of the MHTGR [Modular High-Temperature Gas-Cooled Reactor] reactor cavity cooling system

International Nuclear Information System (INIS)

Conklin, J.C.

1990-04-01

The Reactor Cavity Cooling System (RCCS) of the Modular High- Temperature Gas-Cooled Reactor (MHTGR) proposed by the U.S. Department of Energy is designed to remove the nuclear afterheat passively in the event that neither the heat transport system nor the shutdown cooling circulator subsystem is available. A computer dynamic simulation for the physical and mathematical modeling of and RCCS is described here. Two conclusions can be made form computations performed under the assumption of a uniform reactor vessel temperature. First, the heat transferred across the annulus from the reactor vessel and then to ambient conditions is very dependent on the surface emissivities of the reactor vessel and RCCS panels. These emissivities should be periodically checked to ensure the safety function of the RCCS. Second, the heat transfer from the reactor vessel is reduced by a maximum of 10% by the presence of steam at 1 atm in the reactor cavity annulus for an assumed constant in the transmission of radiant energy across the annulus can be expected to result in an increase in the reactor vessel temperature for the MHTGR. Further investigation of participating radiation media, including small particles, in the reactor cavity annulus is warranted. 26 refs., 7 figs., 1 tab

EFFECT OF THE FILL VENTILATION WINDOW ON PERFORMANCE OF A NATURAL DRAFT COOLING TOWER SUBJECTED TO CROSS-WINDS

Directory of Open Access Journals (Sweden)

K. V. Dobrego

2016-01-01

Full Text Available Various aerodynamic design elements and technics (wind deflectors, wind walls, etc. are utilized for improvement of the thermal efficiency of the natural draft cooling towers, particularly in conditions of cross wind. One of the technical methods, proposed by engineers of Belarus Academy of Sciences, is installation of the ventilation window in the center of the fill. This method is substantiated by the fact that the flow of cooling gas obtains maximum temperature and humidity near the center of the under-fill space of cooling tower and, as a consequence, performs minimal heat exchange. The influence of the fill ventilation window and wind deflectors in the inlet windows of the cooling tower on its thermal performance in condition of cross-wind is investigated in the paper numerically. The cooling tower of the “Woo-Jin” power plant (China 150 m of the height and 114 m of the base diameter was taken as a prototype. The analogy (equivalence between the heat and mass transfer was taken into consideration, which enabled us to consider single-phase flow and perform complicated 3D simulation by using modern personal computers. Heat transfer coefficient for the fill and its hydrodynamic resistance were defined by using actual data on total flow rate in the cooling tower. The numerical model and computational methods were tested and verified in numerous previous works. The non-linear dependence of the thermal performance of the cooling tower on wind velocity (with the minimum in vicinity of Ucr ~ 8 m/s for the simulated system was demonstrated. Calculations show that in the condition of the average wind speed the fill ventilation window doesn’t improve, but slightly decrease (by 3–7 % performance of the cooling tower. Situation changes in the condition of strong winds Ucw > 12 m/s, which are not typical for Belarus. Utilization of airflow deflectors at the inlet windows of cooling tower, conversely, increases thermal performance of the

Optimal thermal-hydraulic performance for helium-cooled divertors

International Nuclear Information System (INIS)

Izenson, M.G.; Martin, J.L.

1996-01-01

Normal flow heat exchanger (NFHX) technology offers the potential for cooling divertor panels with reduced pressure drops (<0.5% Δp/p), reduced pumping power (<0.75% pumping/thermal power), and smaller duct sizes than conventional helium heat exchangers. Furthermore, the NFHX can easily be fabricated in the large sizes required for divertors in large tokamaks. Recent experimental and computational results from a program to develop NFHX technology for divertor coolings using porous metal heat transfer media are described. We have tested the thermal and flow characteristics of porous metals and identified the optimal heat transfer material for the divertor heat exchanger. Methods have been developed to create highly conductive thermal bonds between the porous material and a solid substrate. Computational fluid dynamics calculations of flow and heat transfer in the porous metal layer have shown the capability of high thermal effectiveness. An 18-kW NFHX, designed to meet specifications for the international Thermonuclear Experimental Reactor divertor, has been fabricated and tested for thermal and flow performance. Preliminary results confirm design and fabrication methods. 11 refs., 12 figs., 1 tab

Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring

Directory of Open Access Journals (Sweden)

Zheng Zuo

2014-01-01

Full Text Available Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting vector machine (SVM technology is applied to mine the data. The thermal performances of iron pipes and high-density polyethylene (HDPE pipes are compared. The data mining result shows that iron pipe has a better heat removal performance when flow rate is lower than 50 L/min. It has revealed that a turning flow rate exists for iron pipe which is 80 L/min. The prediction and classification results obtained from the data mining model agree well with the monitored data, which illustrates the validness of the approach.

Development of a prototype thermoelectric space cooling system using phase change material to improve the performance

Science.gov (United States)

Zhao, Dongliang

The thermoelectric cooling system has advantages over conventional vapor compression cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no refrigerant, being powered by direct current, and easily switching between cooling and heating modes. However, it has been long suffering from its relatively high cost and low energy efficiency, which has restricted its usage to niche applications, such as space missions, portable cooling devices, scientific and medical equipment, where coefficient of performance (COP) is not as important as reliability, energy availability, and quiet operation environment. Enhancement of thermoelectric cooling system performance generally relies on two methods: improving thermoelectric material efficiency and through thermoelectric cooling system thermal design. This research has been focused on the latter one. A prototype thermoelectric cooling system integrated with phase change material (PCM) thermal energy storage unit for space cooling has been developed. The PCM thermal storage unit used for cold storage at night, functions as the thermoelectric cooling system's heat sink during daytime's cooling period and provides relatively lower hot side temperature for the thermoelectric cooling system. The experimental test of the prototype system in a reduced-scale chamber has realized an average cooling COP of 0.87, with the maximum value of 1.22. Another comparison test for efficacy of PCM thermal storage unit shows that 35.3% electrical energy has been saved from using PCM for the thermoelectric cooling system. In general, PCM faces difficulty of poor thermal conductivity at both solid and liquid phases. This system implemented a finned inner tube to increase heat transfer during PCM charging (melting) process that directly impacts thermoelectric system's performance. A simulation tool for the entire system has been developed including mathematical models for a single thermoelectric module

Performance investigation of solid desiccant evaporative cooling system configurations in different climatic zones

International Nuclear Information System (INIS)

Ali, Muzaffar; Vukovic, Vladimir; Sheikh, Nadeem Ahmed; Ali, Hafiz M.

2015-01-01

Highlights: • Five configurations of a DEC system are analyzed in five climate zones. • DEC system model configurations are developed in Dymola/Modelica. • Performance analysis predicted a suitable DEC system configuration for each climate zone. • Results show that climate of Vienna, Sao Paulo, and Adelaide favors the ventilated-dunkle cycle. • While ventilation cycle configuration suits the climate of Karachi and Shanghai. - Abstract: Performance of desiccant evaporative cooling (DEC) system configurations is strongly influenced by the climate conditions and varies widely in different climate zones. Finding the optimal configuration of DEC systems for a specific climatic zone is tedious and time consuming. This investigation conducts performance analysis of five DEC system configurations under climatic conditions of five cities from different zones: Vienna, Karachi, Sao Paulo, Shanghai, and Adelaide. On the basis of operating cycle, three standard and two modified system configurations (ventilation, recirculation, dunkle cycles; ventilated-recirculation and ventilated-dunkle cycles) are analyzed in these five climate zones. Using an advance equation-based object-oriented (EOO) modeling and simulation approach, optimal configurations of a DEC system are determined for each climate zone. Based on the hourly climate data of each zone for its respective design cooling day, performance of each system configuration is estimated using three performance parameters: cooling capacity, COP, and cooling energy delivered. The results revealed that the continental/micro-thermal climate of Vienna, temperate/mesothermal climate of Sao Paulo, and dry-summer subtropical climate of Adelaide favor the use of ventilated-dunkle cycle configuration with average COP of 0.405, 0.89 and 1.01 respectively. While ventilation cycle based DEC configuration suits arid and semiarid climate of Karachi and another category of temperate/mesothermal climate of Shanghai with average COP of

Experimental study of the influence of atmospheric conditions on the performance of natural draft dry cooling towers

International Nuclear Information System (INIS)

Markoczy, G.; Staempfli, E.

1977-08-01

The heat dissipation of cooling towers is influenced by atmospheric conditions. In order to establish these influences EIR conducted measurements on a natural draft dry cooling tower. During two measuring campaigns with a duration of total 10 weeks the performance of the cooling tower, the ambient air temperatures, the wind velocities and directions as well as air temperature at the top of the tower and in front of the heat exchangers were continuously measured and registered. The results achieved enable the quantitative description of the influence of the ambient air temperature, wind and temperature inversion on the performance of natural draft dry cooling towers. (Auth.)

Consideration of emergency source terms for pebble-bed high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Tao, Liu; Jun, Zhao; Jiejuan, Tong; Jianzhu, Cao

2009-01-01

Being the last barrier in the nuclear power plant defense-in-depth strategy, emergency planning (EP) is an integrated project. One of the key elements in this process is emergency source terms selection. Emergency Source terms for light water reactor (LWR) nuclear power plant (NPP) have been introduced in many technical documents, and advanced NPP emergency planning is attracting attention recently. Commercial practices of advanced NPP are undergoing in the world, pebble-bed high-temperature gas-cooled reactor (HTGR) power plant is under construction in China which is considered as a representative of advanced NPP. The paper tries to find some pieces of suggestion from our investigation. The discussion of advanced NPP EP will be summarized first, and then the characteristics of pebble-bed HTGR relating to EP will be described. Finally, PSA insights on emergency source terms selection and current pebble-bed HTGR emergency source terms suggestions are proposed

Effects of oral rehydration and external cooling on physiology, perception, and performance in hot, dry climates.

Science.gov (United States)

Muñoz, C X; Carney, K R; Schick, M K; Coburn, J W; Becker, A J; Judelson, D A

2012-12-01

Only limited research evaluates possible benefits of combined drinking and external cooling (by pouring cold water over the body) during exercise. Therefore, this study examined cold water drinking and external cooling on physiological, perceptual, and performance variables in hot, dry environments. Ten male runners completed four trials of walking 90 min at 30% VO(2max) followed by running a 5-km time trial in 33 ± 1 °C and 30 ± 4% relative humidity. Trials examined no intervention (CON), oral rehydration (OR), external cooling (EC), and oral rehydration plus external cooling (OR + EC). Investigators measured rectal temperature, skin temperatures, heart rate, thirst, thermal sensation, and ratings of perceived exertion (RPE). Oral rehydration (OR and OR + EC) significantly lowered heart rate (P External cooling (EC and OR + EC) significantly reduced chest and thigh temperature (P external cooling (CON and OR) during low-intensity exercise. Performance exhibited no differences (CON = 23.86 ± 4.57 min, OR = 22.74 ± 3.20 min, EC = 22.96 ± 3.11 min, OR + EC = 22.64 ± 3.73 min, P = 0.379). Independent of OR, pouring cold water on the body benefited skin temperature, thermal sensation, and RPE during low-intensity exercise in hot, dry conditions but failed to influence high-intensity performance. © 2012 John Wiley & Sons A/S.

Cooling performance of R510A in domestic water purifiers

International Nuclear Information System (INIS)

Park, Ki Jung; Lee, Yo Han; Jung, Dong Soo

2010-01-01

Cooling performance of R510A is examined both numerically and experimentally in an effort to replace HFC134a in the refrigeration system of domestic water purifiers. Although the use of HFC134a is currently dominant, it is being phased out in Europe and most developed countries due to its high potential contribution to global warming. To solve this problem, cycle simulation and experimental measurements are conducted with a new refrigerant mixture of 88%RE170/12%R600a using actual domestic water purifiers. This mixture has been recently numbered and listed as R510A by ASHRAE. Test results show that, due to the small internal volume of the refrigeration system of the domestic water purifiers, system performance with R510A is greatly influenced by the amount of charge. With the optimum charge amount of 20 to 21 g, approximately 50% that of HFC134a, the energy consumption of R510A is 22.3% lower than that of HFC134a. The compressor discharge temperature of R510A is 3.7 .deg. C lower than that of HFC134a at the optimum charge. Overall, R510A, a new, long term, and environmentally safe refrigerant, is a good alternative for HFC134a. Furthermore, it requires only minor changes in the refrigeration system of the domestic water purifiers

Role of bacterial adhesion in the microbial ecology of biofilms in cooling tower systems.

Science.gov (United States)

Liu, Yang; Zhang, Wei; Sileika, Tadas; Warta, Richard; Cianciotto, Nicholas P; Packman, Aaron

2009-01-01

The fate of the three heterotrophic biofilm forming bacteria, Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. in pilot scale cooling towers was evaluated both by observing the persistence of each species in the recirculating water and the formation of biofilms on steel coupons placed in each cooling tower water reservoir. Two different cooling tower experiments were performed: a short-term study (6 days) to observe the initial bacterial colonization of the cooling tower, and a long-term study (3 months) to observe the ecological dynamics with repeated introduction of the test strains. An additional set of batch experiments (6 days) was carried out to evaluate the adhesion of each strain to steel surfaces under similar conditions to those found in the cooling tower experiments. Substantial differences were observed in the microbial communities that developed in the batch systems and cooling towers. P. aeruginosa showed a low degree of adherence to steel surfaces both in batch and in the cooling towers, but grew much faster than K. pneumoniae and Flavobacterium in mixed-species biofilms and ultimately became the dominant organism in the closed batch systems. However, the low degree of adherence caused P. aeruginosa to be rapidly washed out of the open cooling tower systems, and Flavobacterium became the dominant microorganism in the cooling towers in both the short-term and long-term experiments. These results indicate that adhesion, retention and growth on solid surfaces play important roles in the bacterial community that develops in cooling tower systems.

Further investigation on the performance of a shower cooling tower

International Nuclear Information System (INIS)

Qi Xiaoni; Liu Zhenyan

2008-01-01

This study was prompted by the need to design towers for applications in which, due to salt deposition on the packing and subsequent blockage, the use of tower packing is not practical. In the previous model we presented [Qi Xiaoni, Liu Zhenyan, Li Dandan. Performance characteristics of a shower cooling tower. Energy Convers Manage 2007;48(1):193-203.], three critical assumptions were made to reduce the complexity and computational time, which can also reduce the models' accuracy. Accurate modelling of the operating process is a determining factor both for designing the shower cooling tower (SCT) and for optimising its operation. In this paper, we derive a new model without applying the three assumptions. According to the condition of the outlet air, the governing equations consider two cases, including the supersaturated and unsaturated states. This model is used to predict the performance of a full scale SCT located in China with different conditions for validation. The differences in the heat and mass transfer analyses of the two models are described at different atmospheric conditions

Theoretical insight of adsorption cooling

KAUST Repository

Chakraborty, Anutosh

2011-06-03

This letter proposes and presents a thermodynamic formulation to calculate the energetic performances of an adsorption cooler as a function of pore widths and volumes of solid adsorbents. The simulated results in terms of the coefficient of performance are validated with experimental data. It is found from the present analysis that the performance of an adsorption cooling device is influenced mainly by the physical characteristics of solid adsorbents, and the characteristics energy between the adsorbent-adsorbate systems. The present study confirms that there exists a special type of silicagel having optimal physical characteristics that allows us to obtain the best performance.

Theoretical insight of adsorption cooling

KAUST Repository

Chakraborty, Anutosh; Leong, Kai Choong; Thu, Kyaw; Saha, Bidyut Baran; Ng, Kim Choon

2011-01-01

This letter proposes and presents a thermodynamic formulation to calculate the energetic performances of an adsorption cooler as a function of pore widths and volumes of solid adsorbents. The simulated results in terms of the coefficient of performance are validated with experimental data. It is found from the present analysis that the performance of an adsorption cooling device is influenced mainly by the physical characteristics of solid adsorbents, and the characteristics energy between the adsorbent-adsorbate systems. The present study confirms that there exists a special type of silicagel having optimal physical characteristics that allows us to obtain the best performance.

Numerical Analysis for Heat transfer characteristic of Helium cooling system in Helium cooled ceramic reflector Test Module Blanket (HCCR-TBM)

Energy Technology Data Exchange (ETDEWEB)

Park, Seong Dae; Lee, Dong Won; Jin, Hyung Gon; Lee, Eo Hwak; Yoon, Jae Sung; Kim, Suk Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The main objectives of ITER project can be summarized into three types as follows - Plasma operation for a long time - Large tokamak device technology - Test blanket module (TBM) installation and verification The thermal-hydraulic analysis was performed in the He cooling channel in the BZ region of the HCCR TBM. The maximum temperature in the breeder material is equal to the limit temperature in the present design cooling channel. Nuclear fusion energy has advantage in terms of safety, resource availability, cost and waste management. There is not enough experimental results about the fusion reactor due to the severe experiments restrictions like vacuum environment, plasma production and significant nuclear heating at the same time. Much research and time is required for the commercial fusion reactor. For technical verification against the commercialization of fusion reactor, 7 countries which are EU, USA, Japan, Russia, China, India, and South Korea are building an ITER in the south of France. New designed cooling channels were proposed to improve the cooling performance. The swirl flow accelerates the mixture flow in the channels.

Thermal performance of cooling system for a laptop computer using a boiling enhancement microstructure

International Nuclear Information System (INIS)

Cho, N. H.; Jeong, W. Y.; Park, S. H.

2008-01-01

The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at 95 .deg. C

Thermal performance of cooling system for a laptop computer using a boiling enhancement microstructure

Energy Technology Data Exchange (ETDEWEB)

Cho, N. H.; Jeong, W. Y.; Park, S. H. [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

2008-07-01

The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at 95 .deg. C.

Cooling Performance of TBM-shield Designed for Manufacturability

International Nuclear Information System (INIS)

Park, Seong Dae; Lee, Dong Won; Kim, Dong Jun; Yoon, Jae Sung; Ahn, Mu Young

2016-01-01

Helium cooled ceramic reflector (HCCR) test blanket module (TBM) is composed of four sub-modules and a common back manifold (BM). The associated shield is a water-cooled 316L(N)-IG block with internal cooling channels. The purpose of the TBM-shield is to make the condition with the allowable neutron flux and dose rate level. The radially continuous layers of water and structure were configured. The main purpose of the shield is to reduce the neutron flux by absorbing the neutron in the structure. The water could act as the moderator and cool down the structure which is heated due to the reaction with the neutrons. The moderated neutrons are easily absorbed by the structure. It could meet the criteria for the minimum neutron flux by increasing the thickness of structure. The formation of inside cooling channel in the TBM-shield should be considered while maintaining the allowable temperature range. In this work, a manufacturing process including the formation of inside cooling channel was presented. Current design and thermal analysis results for the TBM-shield were presented. The geometry of the shield blocks was considerably changed. The coolant channel was exposed to the outer surface of the TBM-shield. The overall manufacturing process is simplified compared with the previous process of CD model

Cooling Performance of TBM-shield Designed for Manufacturability

Energy Technology Data Exchange (ETDEWEB)

Park, Seong Dae; Lee, Dong Won; Kim, Dong Jun; Yoon, Jae Sung [KAERI, Daejeon (Korea, Republic of); Ahn, Mu Young [NFRI, Daejeon (Korea, Republic of)

2016-05-15

Helium cooled ceramic reflector (HCCR) test blanket module (TBM) is composed of four sub-modules and a common back manifold (BM). The associated shield is a water-cooled 316L(N)-IG block with internal cooling channels. The purpose of the TBM-shield is to make the condition with the allowable neutron flux and dose rate level. The radially continuous layers of water and structure were configured. The main purpose of the shield is to reduce the neutron flux by absorbing the neutron in the structure. The water could act as the moderator and cool down the structure which is heated due to the reaction with the neutrons. The moderated neutrons are easily absorbed by the structure. It could meet the criteria for the minimum neutron flux by increasing the thickness of structure. The formation of inside cooling channel in the TBM-shield should be considered while maintaining the allowable temperature range. In this work, a manufacturing process including the formation of inside cooling channel was presented. Current design and thermal analysis results for the TBM-shield were presented. The geometry of the shield blocks was considerably changed. The coolant channel was exposed to the outer surface of the TBM-shield. The overall manufacturing process is simplified compared with the previous process of CD model.

Alternative geometry for cylindrical natural draft cooling tower with higher cooling efficiency under crosswind condition

International Nuclear Information System (INIS)

Goodarzi, M.; Ramezanpour, R.

2014-01-01

Highlights: • Alternative cross sections for natural draft cooling tower were proposed. • Numerical solution was applied to study thermal and hydraulic performances. • Thermal and hydraulic performances were assessed by comparative parameters. • Cooling tower with elliptical cross section had better thermal performance under crosswind. • It could successfully used at the regions with invariant wind direction. - Abstract: Cooling efficiency of a natural draft dry cooling tower may significantly decrease under crosswind condition. Therefore, many researchers attempted to improve the cooling efficiency under this condition by using structural or mechanical facilities. In this article, alternative shell geometry with elliptical cross section is proposed for this type of cooling tower instead of usual shell geometry with circular cross section. Thermal performance and cooling efficiency of the two types of cooling towers are numerically investigated. Numerical simulations show that cooling tower with elliptical cross section improves the cooling efficiency compared to the usual type with circular cross section under high-speed wind moving normal to the longitudinal diameter of the elliptical cooling tower

Experimental investigation of gas turbine airfoil aerodynamic performance without and with film cooling in an annular sector cascade

Energy Technology Data Exchange (ETDEWEB)

Wiers, S.H.

2002-02-01

subject, as well as state of the art in secondary flow, single cooling jet behavior and film cooling. An overview of existing linear, annular and rotating annular test facilities is also given. The second part deals with the design and instrumentation as well as the measuring technique used for the performed investigations. Surface flow visualization has been performed to get a first idea about the secondary flow. Aerodynamic performance measurements have been conducted by means of five-hole pneumatic pressure probe traverses at 98%, 106% and 140% of c{sub ax} downstream of the cascade to gain information about the secondary flow and primary loss distribution. The variation of the Reynolds number and turbulence level show an overall loss increase for higher turbulence levels and Reynolds numbers due to higher mixing losses. Experimental investigations in terms of surface flow visualization and 5 hole pressure probe traverse of the influence of film cooling on the secondary flow effects and the losses of the cascade have been performed on a modem three dimensional nozzle guide vane with shower head cooling at the leading edge, four film cooling rows at the suction side, two film cooling rows at the pressure side and trailing edge ejection. The results of the flow visualization and pressure probe traverse show that the secondary flow region is only slightly effected by the ejection of low momentum cooling air. The cooling jets are deflected towards the hub, due to the low energy contents. With increasing mass flux ratio, respectively momentum flux ratio, the expanded secondary flow area at the trailing edge decreases. A rapid increase of the mixing loss at the midsection for ejection of high mass flow ratios in a highly accelerated flow at the suction side is observed. The coolant is seen, in every case, to increase the loss compared with the uncooled case. This is in accordance with the findings of most authors with regard to airfoil surface cooling, but the decrease in

Thermal performance experiments on ultimate heat sinks, spray ponds, and cooling ponds

International Nuclear Information System (INIS)

Hadlock, R.K.

1976-12-01

A program of measurement on a Battelle-Northwest (BNW) spray pond has been completed to prove an integrated instrumentation system for application in future field experiments. The measurement programs in the field will produce data of relevance to the design and understanding of performance for ultimate heat sinks as components of emergency core cooling systems. In the absence of active emergency cooling systems, the data will be obtained on analog systems--prime candidates among these are the naturally-occurring hot ponds at Yellowstone National Park and man-made hot cooling ponds at Savannah River National Laboratory as well as spray ponds at various industrial facilities. The proof experiment has provided data that not only illustrate the effectiveness of the instrumentation system but also display interesting site-specific heat transfer processes. The data to be obtained in the field will also be site specific but must be of generic applicability in modeling for design and performance purposes. The integrated instrumentation system will evolve, through modest modifications and substantial supplementation, to provide the requisite data for the more demanding situation of work in and about hot water

NKS-R ExCoolSe mid-term report KTH severe accidents research relevant to the NKS-ExCoolSe project

International Nuclear Information System (INIS)

Hyun Sun Park; Truc-Nam Dinh

2006-04-01

The present mid-term progress report is prepared on the recent results from the KTH severe accident research program relevant to the objective of the ExCoolSe project sponsored by the NKS-R program. The previous PRE-MELT-DEL project at KTH sponsored by NKS provided an extensive assessment on the remaining issues of severe accidents in general and suggested the key issues to be resolved such as coolability and steam explosion energetics in ex-vessel which became a backbone of the ExCoolSe project in NKS. The EXCOOLSE project has been integrated with, and leveraged on, parallel research program at KTH on severe accident phenomena the MSWI project which is funded by the APRI program, SKI in Sweden and HSK in Switzerland and produced more understanding of the key remaining issues. During last year, the critical assessment of the existing knowledge and current SAMG and designs of Nordic BWRs identified the research focus and initiated the new series of research activities toward the resolution of the key remaining issues specifically pertaining to the Nordic BWRs.(au)

Performance Analysis of Photovoltaic Panels with Earth Water Heat Exchanger Cooling

Directory of Open Access Journals (Sweden)

Jakhar Sanjeev

2016-01-01

Full Text Available The operating temperature is an important factor affecting the performance and life span of the Photovoltaic (PV panels. The rising temperature can be maintained within certain limit using proper cooling techniques. In the present research a novel system for cooling of PV panels named as Earth Water Heat Exchanger (EWHE is proposed and modelled in transient analysis simulation tool (TRNSYS v17.0 for the conditions of Pilani, Rajasthan (India.The various parameters which include cell temperature, PV power output and cell efficiency are observed with respect to variation in mass flow rate of fluid. Simulation results of the system without cooling show that the maximum PV panel temperature reached up to 79.31 °C with electrical efficiency dropped to 9% during peak sunshine hour. On the other hand, when PV panels are coupled with EWHE system, the panel temperature drops to 46.29 °C with an efficiency improving to 11% for a mass flow rate of 0.022 kg/s. In the end the cooling potential of EWHE is found to be in direct correlation with mass flow rate. The proposed system is very useful for the arid regions of western India which are blessed with high solar insolation throughout the year.

Thermal performance of a multiple PCM thermal storage unit for free cooling

International Nuclear Information System (INIS)

Mosaffa, A.H.; Infante Ferreira, C.A.; Talati, F.; Rosen, M.A.

2013-01-01

Highlights: ► Numerical analysis on the performance of a thermal storages as free cooling system. ► Employing multiple PCMs to enhance heat transfer rate in thermal storages. ► Using an effective heat capacity method, the phase change parameters are determined. ► The effect of the slabs size and air channel thickness on COP is investigated. - Abstract: As demand for refrigeration and air conditioning increased during the last decade, the opportunities have expanded for using thermal energy storage (TES) systems in an economically advantageous manner in place of conventional cooling plants. Many cool storage systems use phase change materials (PCMs) and achieve peak load shifting in buildings. This work presents numerical investigations of the performance enhancement of a free cooling system using a TES unit employing multiple PCMs. The TES unit is composed of a number of rectangular channels for the flowing heat transfer fluid, separated by PCM slabs. Using the effective heat capacity method, the melting and solidification of the PCM is solved. The forced convective heat transfer inside the channels is analyzed by solving the energy equation, which is coupled with the heat conduction equation in the container wall. The effect of design parameters such as PCM slab length, thickness and fluid passage gap on the storage performance is also investigated using an energy based optimization. The results show that a system which can guarantee comfort conditions for the climate of Tabriz, Iran has an optimum COP of 7.0. This could be achieved by a combination of CaCl 2 ·6H 2 O with RT25 with the optimum air channel thickness of 3.2 mm, length of 1.3 m and PCM slab thickness of 10 mm

Effect of solar radiation on the performance of cross flow wet cooling tower in hot climate of Iran

Science.gov (United States)

Banooni, Salem; Chitsazan, Ali

2016-11-01

In some cities such as Ahvaz-Iran, the solar radiation is very high and the annual-mean-daily of the global solar radiation is about 17.33 MJ m2 d-1. Solar radiation as an external heat source seems to affect the thermal performance of the cooling towers. Usually, in modeling cooling tower, the effects of solar radiation are ignored. To investigate the effect of sunshade on the performance and modeling of the cooling tower, the experiments were conducted in two different states, cooling towers with and without sunshade. In this study, the Merkel's approach and finite difference technique are used to predict the thermal behavior of cross flow wet cooling tower without sunshade and the results are compared with the data obtained from the cooling towers with and without sunshade. Results showed that the sunshade is very efficient and it reduced the outlet water temperature, the approach and the water exergy of the cooling tower up to 1.2 °C, 15 and 1.1 %, respectively and increased the range and the efficiency of the cooling tower up to 29 and 37 %, respectively. Also, the sunshade decreased the error between the experimental data of the cooling tower with sunshade and the modeling results of the cooling tower without sunshade 1.85 % in average.

TRAC analysis of passive containment cooling system performance

International Nuclear Information System (INIS)

Arai, Kenji; Kataoka, Kazuyoshi; Nagasaka, Hideo

1993-01-01

A passive containment cooling system (PCCS) is a promising concept to improve the reliability of decay heat removal during an accident. Toshiba has carried out analytical studies for PCCS development in addition to experimental studies, using a best estimate thermal hydraulic computer code TRAC. In order to establish an analytical model for the PCCS performance analysis, it is necessary for the analytical model to be qualified against experimental results and thoroughly address the phenomena important for PCCS performance analysis. In this paper, the TRAC qualification for PCCS application is reported. A TRAC model has been verified against a drain line break simulation test conducted at the PCCS integral test facility, GIRAFFE. The result shows that the TRAC model can accurately predict the major system response and the PCCS performance in the drain line break test. In addition, the results of several sensitivity analyses, showing various points concerning the modeling in the PCCS performance analysis, have been reported. The analyses have been carried out for the SBWR and the analytical points are closely related to important phenomena which can affect PCCS performance

Skin cooling on contact with cold materials: the effect of blood flow during short-term exposures.

Science.gov (United States)

Jay, Ollie; Havenith, George

2004-03-01

This study investigates the effect of blood flow upon the short-term (cooling response in order to ascertain whether sufferers of circulatory disorders, such as the vasospastic disorder Raynaud's disease, are at a greater risk of cold injury than people with a normal rate of blood flow. Eight female volunteers participated, touching blocks of stainless steel and nylon with a finger contact force of 2.9 N at a surface temperature of -5 degrees C under occluded and vasodilated conditions. Contact temperature (Tc) of the finger pad was measured over time using a T-type thermocouple. Forearm blood flow was measured using strain gauge plethysmography. Contact cooling responses were analysed by fitting a modified Newtonian cooling curve. A significant difference was found between the starting skin temperatures for the two blood flow conditions (Peffect of blood flow was found upon any of the derived cooling curve parameters characterizing the skin cooling response (P>0.05). It is hypothesized that the finger contact force used (2.9 N) and the resultant pressure upon the tissue of the contact finger pad restricted the blood supply to the contact area under both blood flow conditions; therefore, no effect of blood flow was found upon the parameters describing the contact cooling response. Whilst the findings of this study are sufficient to draw a conclusion for those in a working environment, i.e. contact forces below 2.9 N will seldom be encountered, a further study will be required to ascertain conclusively whether blood flow does affect the contact cooling response at a finger contact force low enough to allow unrestricted blood flow to the finger pad. Further protocol improvements are also recommended.

Assessment of the effect of nitrogen gas on passive containment cooling system performance

International Nuclear Information System (INIS)

Ha, Huiun; Suh, Jungsoo

2016-01-01

As a part of the passive containment cooling system (PCCS) of Innovative PWR development project, we have been investigating the effect of the nitrogen gas released from safety injection tank (SIT) on PCCS performance. With the design characteristics of APR1400 and conceptual design of PCCS, we developed a GOTHIC model of the APR1400 containment with PCCS. The calculation model is described herein, and representative results from the calculation are presented as well. The results of the present work will be used for the design of PCCS. APR1400 GOTHIC model was developed for assessment on the effect of SIT nitrogen gas on passive containment cooling system performance. Calculation results confirmed that influence of nitrogen gas release is negligible; however, further studies should be performed to confirm effect of non-condensable gas on the final performance of PCCS. These insights are important for developing the PCCS of Innovative PWR

Assessment of the effect of nitrogen gas on passive containment cooling system performance

Energy Technology Data Exchange (ETDEWEB)

Ha, Huiun; Suh, Jungsoo [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

As a part of the passive containment cooling system (PCCS) of Innovative PWR development project, we have been investigating the effect of the nitrogen gas released from safety injection tank (SIT) on PCCS performance. With the design characteristics of APR1400 and conceptual design of PCCS, we developed a GOTHIC model of the APR1400 containment with PCCS. The calculation model is described herein, and representative results from the calculation are presented as well. The results of the present work will be used for the design of PCCS. APR1400 GOTHIC model was developed for assessment on the effect of SIT nitrogen gas on passive containment cooling system performance. Calculation results confirmed that influence of nitrogen gas release is negligible; however, further studies should be performed to confirm effect of non-condensable gas on the final performance of PCCS. These insights are important for developing the PCCS of Innovative PWR.

Numerical investigation of the energy performance of a guideless irregular heat and mass exchanger with corrugated heat transfer surface for dew point cooling

International Nuclear Information System (INIS)

Xu, Peng; Ma, Xiaoli; Diallo, Thierno M.O.; Zhao, Xudong; Fancey, Kevin; Li, Deying; Chen, Hongbing

2016-01-01

The paper presents an investigation into the energy performance of a novel irregular heat and mass exchanger for dew point cooling which, compared to the existing flat-plate heat exchangers, removed the use of the channel supporting guides and implemented the corrugated heat transfer surface, thus expecting to achieve the reduced air flow resistance, increased heat transfer area, and improved energy efficiency (i.e. Coefficient of Performance (COP)) of the air cooling process. CFD simulation was carried out to determine the flow resistance (K) factors of various elements within the dry and wet channels of the exchanger, while the ‘finite-element’ based ‘Newton-iteration’ numerical simulation was undertaken to investigate its cooling capacity, cooling effectiveness and COP at various geometrical and operational conditions. Compared to the existing flat-plate heat and mass exchangers with the same geometrical dimensions and operational conditions, the new irregular exchanger could achieve 32.9%–37% higher cooling capacity, dew-point and wet-bulb effectiveness, 29.7%–33.3% higher COP, and 55.8%–56.2% lower pressure drop. While undertaking dew point air cooling, the irregular heat and mass exchanger had the optimum air velocity of 1 m/s within the flow channels and working-to-intake air ratio of 0.3, which allowed the highest cooling capacity and COP to be achieved. In terms of the exchanger dimensions, the optimum height of the channel was 5 mm while its length was in the range 1–2 m. Overall, the proposed irregular heat and mass exchanger could lead to significant enhanced energy performance compared to the existing flat-plate dew point cooling heat exchanger of the same geometrical dimensions. To achieve the same amount cooling output, the irregular heat and mass exchanger had the reduced size and cost against the flat-plate ones. - Highlights: • Numerical investigation of an irregular heat and mass exchanger was undertaken. • A �

Theoretical investigations on improving performance of cooling systems for fuel cell vehicles; Theoretische Untersuchungen zur Kuehlleistungssteigerung durch innovative Kuehlsysteme fuer Brennstoffzellen-Elektrofahrzeuge

Energy Technology Data Exchange (ETDEWEB)

Reichler, Mark

2008-04-01

In this work theoretical investigations are carried out for cooling systems, which are used in fuel cell vehicles. This work focuses mainly on the capability of increasing the heat rejection rate by using new alternative cooling systems and by improving the conventional cooling system. Fuel cell vehicles have a higher demand of heat rejection to the ambient than comparable vehicles with combustion engine. The performance of conventional liquid cooling systems, especially at high loads and high ambient temperatures, is often not sufficient anymore. Hence, cooling systems with improved performance are necessary for fuel cell vehicles. The investigations in this work are based on DaimlerChrysler's ''A-Class'' having a PEM-Fuel Cell system integrated. Specific computational models are developed for radiators and condensers to evaluate the performance of different cooling concepts. The models are validated with experimental data. Based on an intensive investigation in the open literature the state of the art of cooling systems for fuel cell vehicles is depicted. Furthermore new cooling concepts as an alternative to the liquid cooling system are presented. The method of cooling the fuel cell by using two-phase transition shows the greatest capability to increase the cooling performance. Hence, this concept is investigated in detail. Two different concepts with three different refrigerants (R113, R245fa und R236fa) are analyzed. Cooling performance of this concept shows improvement of 18.2 up to 32.6 % compared to the conventional liquid cooling system. Thus, a two phase cooling system represents an alternative cooling system for fuel cell vehicles, which should be closer investigated by experiments. (orig.)

Influence of Stern Shaft Inclination on the Cooling Performance of Water-Lubricated Bearing

Directory of Open Access Journals (Sweden)

Zou Li

2016-01-01

Full Text Available The water film model of the marine water-lubricated stern bearing was established by FLUENT. The influence law of water flow rate on the cooling performance of water-lubricated bearing was studied in consideration of the stern shaft inclination. It will be helpful to improve the performance of marine water-lubricated stern bearing and both security and reliability of propulsion system. The simulation results show that the increase of cooling water flow rate in a certain range can effectively reduce bearing temperature. The bearing temperature rises sharply with thinning of water film thickness which is caused by the increase of inclination angle. Larger inclination angle can deteriorate the operating reliability of bearing.

Whole-body pre-cooling and heat storage during self-paced cycling performance in warm humid conditions.

Science.gov (United States)

Kay, D; Taaffe, D R; Marino, F E

1999-12-01

The aim of this study was to establish the effect that pre-cooling the skin without a concomitant reduction in core temperature has on subsequent self-paced cycling performance under warm humid (31 degrees C and 60% relative humidity) conditions. Seven moderately trained males performed a 30 min self-paced cycling trial on two separate occasions. The conditions were counterbalanced as control or whole-body pre-cooling by water immersion so that resting skin temperature was reduced by approximately 5-6 degrees C. After pre-cooling, mean skin temperature was lower throughout exercise and rectal temperature was lower (P body sweat fell from 1.7+/-0.1 l x h(-1) to 1.2+/-0.1 l h(-1) (P < 0.05). The distance cycled increased from 14.9+/-0.8 to 15.8+/-0.7 km (P < 0.05) after pre-cooling. The results indicate that skin pre-cooling in the absence of a reduced rectal temperature is effective in reducing thermal strain and increasing the distance cycled in 30 min under warm humid conditions.

Evaluation of conceptual Heat Exchanger Design for passive containment cooling system of SMART

Energy Technology Data Exchange (ETDEWEB)

Kim, Min-Ki; Hong, Soon Joon [FNC Tech., Yongin (Korea, Republic of); Kim, Young In; Kim, Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

PCCS(Passive containment cooling system) is the passive safety system which ultimately removes the reactor decay heat. Cooling performance of the air-cooled type and water-circulation cooling type of PCCS were analyzed using CAP version 2.21. The analysis results show the water-circulation cooling PCCS is more effective in lowering the peak pressure and temperature in the containment building. However, the air-cooled PCCS is more effective to the long-term cooling. From this study, the efficiency evaluation results for the two PCCS designs are obtained. These results may be applied in the PCCS design improvement. Moreover, these results will be used as a reference for the later PCCS design and analysis.

The development of a realistic source term for sodium-cooled fast reactors : assessment of current status and future needs.

Energy Technology Data Exchange (ETDEWEB)

LaChance, Jeffrey L.; Phillips, Jesse; Parma, Edward J., Jr.; Olivier, Tara Jean; Middleton, Bobby D.

2011-06-01

Sodium-cooled fast reactors (SFRs) continue to be proposed and designed throughout the United States and the world. Although the number of SFRs actually operating has declined substantially since the 1980s, a significant interest in advancing these types of reactor systems remains. Of the many issues associated with the development and deployment of SFRs, one of high regulatory importance is the source term to be used in the siting of the reactor. A substantial amount of modeling and experimental work has been performed over the past four decades on accident analysis, sodium coolant behavior, and radionuclide release for SFRs. The objective of this report is to aid in determining the gaps and issues related to the development of a realistic, mechanistically derived source term for SFRs. This report will allow the reader to become familiar with the severe accident source term concept and gain a broad understanding of the current status of the models and experimental work. Further, this report will allow insight into future work, in terms of both model development and experimental validation, which is necessary in order to develop a realistic source term for SFRs.

Forced draft wet cooling systems

International Nuclear Information System (INIS)

Daubert, A.; Caudron, L.; Viollet, P.L.

1975-01-01

The disposal of the heat released from a 1000MW power plant needs a natural draft tower of about 130m of diameter at the base, and 170m height, or a cooling system with a draft forced by about forty vans, a hundred meters in diameter, and thirty meters height. The plumes from atmospheric cooling systems form, in terms of fluid mechanics, hot jets in a cross current. They consist in complex flows that must be finely investigated with experimental and computer means. The study, currently being performed at the National Hydraulics Laboratory, shows that as far as the length and height of visible plumes are concerned, the comparison is favorable to some types of forced draft cooling system, for low and medium velocities, (below 5 or 6m/s at 10m height. Beyond these velocities, the forced draft sends the plume up to smaller heights, but the plume is generally more dilute [fr

Experimental assessment of film cooling performance of short cylindrical holes on a flat surface

Science.gov (United States)

Singh, Kuldeep; Premachandran, B.; Ravi, M. R.

2016-12-01

The present study is an experimental investigation of film-cooling over a flat surface from the short cylindrical holes. The film cooling holes used in the combustion chamber and the afterburner liner of an aero engine has length-to-diameter (L/D) typically in the range 1-2, while the cooling holes used in turbine blades has L/D > 3. Based on the classification given in the literature, cooling holes with L/D ≤ 3 are named as short holes and cooling holes with L/D > 3 are named as long holes. Short film cooling holes cause jetting of the secondary fluid whereas the secondary fluid emerging from long holes has characteristics similar to fully developed turbulent flow in pipe. In order to understand the difference in the film cooling performance of long and short cooling holes, experimental study is carried out for five values of L/D in the range 1-5, five injection angles, α = 15°-90° and five mainstream Reynolds number 1.25 × 105-6.25 × 105 and two blowing ratios, M = 0.5-1.0. The surface temperature of the test plate is monitored using infrared thermography. The results obtained from the present study showed that the film-cooling effectiveness is higher for the longest holes (L/D = 5) investigated in the present work in comparison to that for the shorter holes. Short holes are found to give better effectiveness at the lowest investigated injection angle i.e. α = 15° in the near cooling hole region, whereas film cooling effectiveness obtained at injection angle, α = 45° is found to be better than other injection angles for longest investigated holes, i.e. L/D = 5.

Performance enhancement of PV cells through micro-channel cooling

Directory of Open Access Journals (Sweden)

Muzaffar Ali

2015-11-01

Full Text Available Efficiency of a PV cell is strongly dependent on its surface temperature. The current study is focused to achieve maximum efficiency of PV cells even in scorching temperatures in hot climates like Pakistan where the cell surface temperatures can even rise up to around 80 ℃. The study includes both the CFD and real time experimental investigations of a solar panel using micro channel cooling. Initially, CFD analysis is performed by developing a 3D model of a Mono-Crystalline cell with micro-channels to analyze cell surface temperature distribution at different irradiance and water flow rates. Afterwards, an experimental setup is developed for performance investigations under the real conditions of an open climate of a Pakistan's city, Taxila. Two 35W panels are manufactured for the experiments; one is based on the standard manufacturing procedure while other cell is developed with 4mm thick aluminum sheet having micro-channels of cross-section of 1mm by 1mm. The whole setup also includes different sensors for the measurement of solar irradiance, cell power, surface temperature and water flow rates. The experimental results show that PV cell surface temperature drop of around 15 ℃ is achieved with power increment of around 14% at maximum applied water flow rate of 3 LPM. Additionally, a good agreement is also found between CFD and experimental results. Therefore, that study clearly shows that a significant performance improvement of PV cells can be achieved through the proposed cell cooling technique.

Experimental investigation of the performance characteristics of a counterflow wet cooling tower

International Nuclear Information System (INIS)

Lemouari, M.; Boumaza, M.

2010-01-01

An experimental investigation of the performance characteristics of a counter flow wet cooling tower represented by the heat rejected by the tower and its thermal effectiveness is presented in this paper. The tower is filled with a 'VGA.' (Vertical Grid Apparatus) type packing which is 0.42 m high and contains four (04) galvanized 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 - 0.148 m. The investigation is concerned mainly on the effect of the air, water flow rates and the inlet water temperatures on the thermal effectiveness of the cooling tower as well as the heat rejected by this tower from water to be cooled to the air stream discharged into the atmosphere. The two operating regimes which were observed during the air/water contact inside the tower, a Pellicular Regime (PR) and a Bubble and Dispersion Regime (BDR) appear to be important, as The BDR regime enables to cool larger amount of water flow rates, while the Pellicular regime results with higher thermal effectiveness. (authors)

Experimental Flow Performance Evaluation of novel miniaturized Advanced Piezoelectric Dual Cooling Jet

International Nuclear Information System (INIS)

De Bock, H P J; Whalen, B P; Chamarthy, P; Jackson, J L

2012-01-01

In recent years, electronics systems have significantly reduced in size at maintained or increased functionality. This trend has led to an increased demand for smaller and more capable thermal management. However, miniaturization of conventional fan and heat sink cooling systems introduce significant size, weight and efficiency challenges. In this study the flow performance of a novel alternative thin form-factor cooling solution, the advanced piezoelectric dual cooling jet(DCJ), is evaluated. A DCJ is a system where two piezoelectric actuators are excited to produce air flow. The total height of the device is about 1mm. The design of the experimental method for evaluating the equivalent fan-curve of the DCJ device is described in detail. Experimental results in comparison to conventional fan solutions are provided. The DCJ is expected to be a good candidate for thermal management in next generation thin profile consumer electronics.

Computer Simulation Performed for Columbia Project Cooling System

Science.gov (United States)

Ahmad, Jasim

2005-01-01

This demo shows a high-fidelity simulation of the air flow in the main computer room housing the Columbia (10,024 intel titanium processors) system. The simulation asseses the performance of the cooling system and identified deficiencies, and recommended modifications to eliminate them. It used two in house software packages on NAS supercomputers: Chimera Grid tools to generate a geometric model of the computer room, OVERFLOW-2 code for fluid and thermal simulation. This state-of-the-art technology can be easily extended to provide a general capability for air flow analyses on any modern computer room. Columbia_CFD_black.tiff

Performance Evaluation of a Software Engineering Tool for Automated Design of Cooling Systems in Injection Moulding

DEFF Research Database (Denmark)

Jauregui-Becker, Juan M.; Tosello, Guido; van Houten, Fred J.A.M.

2013-01-01

This paper presents a software tool for automating the design of cooling systems for injection moulding and a validation of its performance. Cooling system designs were automatically generated by the proposed software tool and by applying a best practice tool engineering design approach. The two...

Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

Energy Technology Data Exchange (ETDEWEB)

Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

2007-11-15

Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71-0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile. (author)

Experimental study of performance of a dry cooling and dedicated ventilation (DCDV) system under different space cooling load conditions

International Nuclear Information System (INIS)

Jia, Jie; Lee, W.L.; Chen, Hua

2013-01-01

Highlights: • This is an experimental study of the use of DCDV system for achieving the decoupling and energy saving objectives. • The study focuses on side-by-side comparison of the DCDV and conventional systems. • DCDV system can better achieve the desired space air conditions and is more energy efficient. • A prediction model has been developed to relate the possible condensation period with different operating parameters. • The results are useful for wider application of DCDV system. - Abstract: The use of DCDV system for decoupling dehumidification from cooling to achieve energy saving objective for air-conditioning of office environments in Hong Kong was confirmed effective based on simulation studies by the authors. However, given that simulation typically assumes a perfect control and feedback system, whether or not the benefits of DCDV system can be realized in practice, in particular under various space part load ratio (PLR) and sensible heat ratio (SHR) conditions, is subject to experimental verifications. In this study, a prototype which could be switched between the proposed DCDV system mode and the conventional system mode was constructed in a test facility for laboratory experiments. Through two sets of identical experiments under various space cooling load conditions, it was found that if compared to the conventional system, DCDV system could perform slightly better in achieving the desired indoor condition and in reducing the moisture-related air quality problems, but would result in 1–3% higher in cooling output. As for the overall coefficient of performance (COP o ), the DCDV system was found performed better by 5.6–7.2%. Additional experimental analysis was conducted for the development of a prediction model to relate the possible condensation period (ψ) on the DC coil with different operating parameters

Numerical study of the thermo-flow performances of novel finned tubes for air-cooled condensers in power plant

Science.gov (United States)

Guo, Yonghong; Du, Xiaoze; Yang, Lijun

2018-02-01

Air-cooled condenser is the main equipment of the direct dry cooling system in a power plant, which rejects heat of the exhaust steam with the finned tube bundles. Therefore, the thermo-flow performances of the finned tubes have an important effect on the optimal operation of the direct dry cooling system. In this paper, the flow and heat transfer characteristics of the single row finned tubes with the conventional flat fins and novel jagged fins are investigated by numerical method. The flow and temperature fields of cooling air for the finned tubes are obtained. Moreover, the variations of the flow resistance and average convection heat transfer coefficient under different frontal velocity of air and jag number are presented. Finally, the correlating equations of the friction factor and Nusselt number versus the Reynolds number are fitted. The results show that with increasing the frontal velocity of air, the heat transfer performances of the finned tubes are enhanced but the pressure drop will increase accordingly, resulting in the average convection heat transfer coefficient and friction factor increasing. Meanwhile, with increasing the number of fin jag, the heat transfer performance is intensified. The present studies provide a reference in optimal designing for the air-cooled condenser of direct air cooling system.

Analytical solutions for evaluating the thermal performances of wet air cooling coils under both unit and non-unit Lewis Factors

International Nuclear Information System (INIS)

Xia Liang; Chan, M.Y.; Deng, S.M.; Xu, X.G.

2010-01-01

Analytical solutions for evaluating the thermal performances of both chilled water wet cooling coils and direct expansion (DX) wet cooling coils, respectively, under both unit and non-unit Lewis Factors are developed and reported in this paper. The analytical solution was validated by comparing its predictions with those from numerically solving the fundamental governing equations of heat and mass transfer taking place in a wet cooling coil. With the analytical solutions, the distributions of air temperature and humidity ratio along air flow direction in a wet cooling coil can be predicted, and the differences in the thermal performances of the cooling coils under both unit and non-unit Lewis Factors can be identified. The analytical solutions, on one hand, can be a low-cost replacement to numerically solving the fundamental heat and mass transfer governing equations, and on the other hand, is able to deal with evaluating thermal performance for wet air cooling coils operated under both unit and non-unit Lewis Factors.

Impingement jet cooling in gas turbines

CERN Document Server

Amano, R S

2014-01-01

Due to the requirement for enhanced cooling technologies on modern gas turbine engines, advanced research and development has had to take place in field of thermal engineering. Impingement jet cooling is one of the most effective in terms of cooling, manufacturability and cost. This is the first to book to focus on impingement cooling alone.

Numerical evaluation of various gas and coolant channel designs for high performance liquid-cooled proton exchange membrane fuel cell stacks

International Nuclear Information System (INIS)

Sasmito, Agus P.; Kurnia, Jundika C.; Mujumdar, Arun S.

2012-01-01

A careful design of gas and coolant channel is essential to ensure high performance and durability of proton exchange membrane (PEM) fuel cell stack. The channel design should allow for good thermal, water and gas management whilst keeping low pressure drop. This study evaluates numerically the performance of various gas and coolant channel designs simultaneously, e.g. parallel, serpentine, oblique-fins, coiled, parallel-serpentine and a novel hybrid parallel-serpentine-oblique-fins designs. The stack performance and local distributions of key parameters are investigated with regards to the thermal, water and gas management. The results indicate that the novel hybrid channel design yields the best performance as it constitutes to a lower pumping power and good thermal, water and gas management as compared to conventional channels. Advantages and limitation of the designs are discussed in the light of present numerical results. Finally, potential application and further improvement of the design are highlighted. -- Highlights: ► We evaluate various gas and coolant channel designs in liquid-cooled PEM fuel cell stack. ► The model considers coupled electrochemistry, channel design and cooling effect simultaneously. ► We propose a novel hybrid channel design. ► The novel hybrid channel design yields the best thermal, water and gas management which is beneficial for long term durability. ► The novel hybrid channel design exhibits the best performance.

Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger

International Nuclear Information System (INIS)

Youchison, Dennis L.; North, Mart T.

2000-01-01

Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m 2 and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm 2 area. An impressive 10 kW of power was absorbed on an area of 24 cm 2 . Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m 2 using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented

Influence of the ambient temperature on the cooling efficiency of the high performance cooling device with thermosiphon effect

Science.gov (United States)

Nemec, Patrik; Malcho, Milan

2018-06-01

This work deal with experimental measurement and calculation cooling efficiency of the cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description, working principle and construction of cooling device. The main factor affected the dissipation of high heat flux from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. Experimental part describe the measuring method cooling efficiency of the cooling device depending on ambient temperature in range -20 to 40°C and at heat load of electronic components 750 W. Measured results are compared with results calculation based on physical phenomena of boiling, condensation and natural convection heat transfer.

Performance comparison between ethanol phase-change immersion and active water cooling for solar cells in high concentrating photovoltaic system

International Nuclear Information System (INIS)

Wang, Yiping; Wen, Chen; Huang, Qunwu; Kang, Xue; Chen, Miao; Wang, Huilin

2017-01-01

Highlights: • Thermal performances of ethanol phase-change immersion and active water cooling are compared. • Effects of operation parameters on ethanol phase-change immersion are studied. • Optimum filling ratio is 30% for ethanol phase-change immersion cooling system. • Exergy efficiency of ethanol phase-change immersion method increases by 57%. - Abstract: This paper presents an optimized ethanol phase-change immersion cooling method to obtain lower temperature of dense-array solar cells in high concentrating photovoltaic system. The thermal performances of this system were compared with a conventional active water cooling system with minichannels from the perspectives of start-up characteristic, temperature uniformity, thermal resistance and heat transfer coefficient. This paper also explored the influences of liquid filling ratio, absolute pressure and water flow rate on thermal performances. Dense-array LEDs were used to simulate heat power of solar cells worked under high concentration ratios. It can be observed that the optimal filling ratio was 30% in which the thermal resistance was 0.479 °C/W and the heat transfer coefficient was 9726.21 W/(m 2 ·°C). To quantify the quality of energy output of two cooling systems, exergy analysis are conducted and maximum exergy efficiencies were 17.70% and 11.27%, respectively. The experimental results represent an improvement towards thermal performances of ethanol phase-change immersion cooling system due to the reduction in contact thermal resistance. This study improves the operation control and applications for ethanol phase-change immersion cooling technology.

Experiment Investigation on Electrical and Thermal Performances of a Semitransparent Photovoltaic/Thermal System with Water Cooling

Directory of Open Access Journals (Sweden)

Guiqiang Li

2014-01-01

Full Text Available Different from the semitransparent building integrated photovoltaic/thermal (BIPV/T system with air cooling, the semitransparent BIPV/T system with water cooling is rare, especially based on the silicon solar cells. In this paper, a semitransparent photovoltaic/thermal system (SPV/T with water cooling was set up, which not only would provide the electrical power and hot water, but also could attain the natural illumination for the building. The PV efficiency, thermal efficiency, and exergy analysis were all adopted to illustrate the performance of SPV/T system. The results showed that the PV efficiency and the thermal efficiency were about 11.5% and 39.5%, respectively, on the typical sunny day. Furthermore, the PV and thermal efficiencies fit curves were made to demonstrate the SPV/T performance more comprehensively. The performance analysis indicated that the SPV/T system has a good application prospect for building.

Modelling the thermodynamic performance of a concentrated solar power plant with a novel modular air-cooled condenser

International Nuclear Information System (INIS)

Moore, J.; Grimes, R.; Walsh, E.; O'Donovan, A.

2014-01-01

This paper aims at developing a novel air-cooled condenser for concentrated solar power plants. The condenser offers two significant advantages over the existing state-of-the-art. Firstly, it can be installed in a modular format where pre-assembled condenser modules reduce installation costs. Secondly, instead of using large fixed speed fans, smaller speed controlled fans are incorporated into the individual modules. This facility allows the operating point of the condenser to change and continuously maximise plant efficiency. A thorough experimental analysis was performed on a number of prototype condenser designs. This analysis investigated the validly and accuracy of correlations from literature in predicting the thermal and aerodynamic characteristics of different designs. These measurements were used to develop a thermodynamic model to predict the performance of a 50 MW CSP (Concentrated Solar Power) plant with various condenser designs installed. In order to compare different designs with respect to the specific plant capital cost, a techno-economic analysis was performed which identified the optimum size of each condenser. The results show that a single row plate finned tube design, a four row, and a two row circular finned tube design are all similar in terms of their techno-economic performance and offer significant savings over other designs. - Highlights: • A novel air cooled condenser for CSP (Concentrated Solar Power) applications is proposed. • A thorough experimental analysis of various condenser designs was performed. • Heat transfer and flow friction correlations validated for fan generated air flow. • A thermodynamic model to calculate CSP plant output is presented. • Results show the proposed condenser design can continually optimise plant output

The study on the evaporation cooling efficiency and effectiveness of cooling tower of film type

International Nuclear Information System (INIS)

Li Yingjian; You Xinkui; Qiu Qi; Li Jiezhi

2011-01-01

Based on heat and mass transport mechanism of film type cooling, which was combined with an on-site test on counter flow film type cooling tower, a mathematical model on the evaporation and cooling efficiency and effectiveness has been developed. Under typical climatic conditions, air conditioning load and the operating condition, the mass and heat balances have been calculated for the air and the cooling water including the volume of evaporative cooling water. Changing rule has been measured and calculated between coefficient of performance (COP) and chiller load. The influences of air and cooling water parameters on the evaporative cooling efficiency were analyzed in cooling tower restrained by latent heat evaporative cooling, and detailed derivation and computation revealed that both the evaporative cooling efficiency and effectiveness of cooling tower are the same characteristics parameters of the thermal performance of a cooling tower under identical assumptions.

Effect of irreversible processes on the thermodynamic performance of open-cycle desiccant cooling cycles

International Nuclear Information System (INIS)

La, Dong; Li, Yong; Dai, Yanjun; Ge, Tianshu; Wang, Ruzhu

2013-01-01

Highlights: ► Effects of irreversible processes on the performance of desiccant cooling cycle are identified. ► The exergy destructions involved are classified by the properties of the individual processes. ► Appropriate indexes for thermodynamic evaluation are proposed based on thermodynamic analyses. - Abstract: Thermodynamic analyses of desiccant cooling cycle usually focus on the overall cycle performance in previous study. In this paper, the effects of the individual irreversible processes in each component on thermodynamic performance are analyzed in detail. The objective of this paper is to reveal the elemental features of the individual components, and to show their effects on the thermodynamic performance of the whole cycle in a fundamental way. Appropriate indexes for thermodynamic evaluation are derived based on the first and second law analyses. A generalized model independent of the connection of components is developed. The results indicate that as the effectiveness of the desiccant wheel increases, the cycle performance is increased principally due to the significant reduction in exergy carried out by exhaust air. The corresponding exergy destruction coefficient of the cycle with moderate performance desiccant wheel is decreased greatly to 3.9%, which is more than 50% lower than that of the cycle with low performance desiccant wheel. The effect of the heat source is similar. As the temperature of the heat source increases from 60 °C to 90 °C, the percentage of exergy destruction raised by exhaust air increases sharply from 5.3% to 21.8%. High heat exchanger effectiveness improves the cycle performance mainly by lowering the irreversibility of the heat exchanger, using less regeneration heat and pre-cooling the process air effectively

Spray cooling

International Nuclear Information System (INIS)

Rollin, Philippe.

1975-01-01

Spray cooling - using water spraying in air - is surveyed as a possible system for make-up (peak clipping in open circuit) or major cooling (in closed circuit) of the cooling water of the condensers in thermal power plants. Indications are given on the experiments made in France and the systems recently developed in USA, questions relating to performance, cost and environmental effects of spray devices are then dealt with [fr

A quantitative evaluation of the production performance of ice slurry by the oscillatory moving cooled wall method

Energy Technology Data Exchange (ETDEWEB)

Yamada, Masahiko; Fukusako, Shoichiro [Hokkaido Univ., Sapporo (Japan). Graduate School of Engineering; Kawabe, Hiromichi [Senshu Univ., Bibai (Japan). Hokkaido College. Dept. of Agricultural Engineering

2002-03-01

Ice slurry has recently been utilized for a variety of engineering fields such as thermal energy storage and high-density energy transportation. In this paper, as a production method of ice slurry, the oscillatory rotating cooled tube method was proposed. A vertical cooled tube was installed in a test vessel that was filled with ethylene glycol solution being forced to move within an aqueous binary solution to produce the ice slurry. Production performance of ice slurry by the present method was determined under a variety of conditions, such as initial concentration of solution, angular acceleration and rotation angle for the oscillation motion of the cooled tube. The production performance was evaluated analytically by constructing a numerical model. The analysis was made to determine the separation condition of ice layer from the cooled tube surface at first, then the production rate of ice slurry was assessed. It was found from the present study that the ice slurry was produced continuously under the appropriate operating conditions in which the separation of ice layer was caused by oscillating motion of the cooled tube. (Author)

Performance of Metal Cutting on Endmills Manufactured by Cooling-Air and Minimum Quantity Lubrication Grinding

Science.gov (United States)

Inoue, Shigeru; Aoyama, Tojiro

Grinding fluids have been commonly used during the grinding of tools for their cooling and lubricating effect since the hard, robust materials used for cutting tools are difficult to grind. Grinding fluids help prevent a drop in hardness due to burning of the cutting edge and keep chipping to an absolute minimum. However, there is a heightened awareness of the need to improve the work environment and protect the global environment. Thus, the present study is aimed at applying dry grinding, cooling-air grinding, cooling-air grinding with minimum quantity lubrication (MQL), and oil-based fluid grinding to manufacturing actual endmills (HSS-Co). Cutting tests were performed by a vertical machining center. The results indicated that the lowest surface inclination values and longest tool life were obtained by cooling-air grinding with MQL. Thus, cooling-air grinding with MQL has been demonstrated to be at least as effective as oil-based fluid grinding.

Experimental and Numerical Study of the Effects of Acoustic Sound Absorbers on the Cooling Performance of Thermally Active Building Systems

DEFF Research Database (Denmark)

Domínguez, L. Marcos; Kazanci, Ongun Berk; Rage, Nils

2017-01-01

Free-hanging horizontal and vertical sound absorbers are commonly used in buildings for room acoustic control; however, when these sound absorbers are used in combination with Thermally Active Building Systems, they will decrease the cooling performance of Thermally Active Building Systems...... and this will affect the thermal indoor environment in that space. Therefore, it is crucial to be able to quantify and model these effects in the design phase. This study quantifies experimentally the effects of horizontal and vertical free-hanging sound absorbers on the cooling performance of Thermally Active......%, respectively. With vertical sound absorbers, the decrease in cooling performance was 8%, 12%, and 14% for the corresponding cases, respectively. The numerical model predicted closely the cooling performance reduction, air temperatures and ceiling surface temperatures in most cases, while there were differences...

Performance evaluation of radiant cooling system application on a university building in Indonesia

Science.gov (United States)

Satrio, Pujo; Sholahudin, S.; Nasruddin

2017-03-01

The paper describes a study developed to estimate the energy savings potential of a radiant cooling system installed in an institutional building in Indonesia. The simulations were carried out using IESVE to evaluate thermal performance and energy consumption The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption and temperature distribution to determine the proportional energy savings and occupant comfort under different systems. The result was radiant cooling which integrated with a Dedicated Outside Air System (DOAS) could make 41,84% energy savings compared to the installed cooling system. The Computational Fluid Dynamics (CFD) simulation showed that a radiant system integrated with DOAS provides superior human comfort than a radiant system integrated with Variable Air Volume (VAV). Percentage People Dissatisfied was kept below 10% using the proposed system.

Preliminary Analysis on Heat Removal Capacity of Passive Air-Water Combined Cooling Heat Exchanger Using MARS

International Nuclear Information System (INIS)

Kim, Seung-Sin; Jeon, Seong-Su; Hong, Soon-Joon; Bae, Sung-Won; Kwon, Tae-Soon

2015-01-01

Current design requirement for working time of PAFS heat exchanger is about 8 hours. Thus, it is not satisfied with the required cooling capability for the long term SBO(Station Black-Out) situation that is required to over 72 hours cooling. Therefore PAFS is needed to change of design for 72 hours cooling. In order to acquirement of long terms cooling using PAFS, heat exchanger tube has to be submerged in water tank for long time. However, water in the tank is evaporated by transferred heat from heat exchanger tubes, so water level is gradually lowered as time goes on. The heat removal capacity of air cooling heat exchanger is core parameter that is used for decision of applicability on passive air-water combined cooling system using PAFS in long term cooling. In this study, the development of MARS input model and plant accident analysis are performed for the prediction of the heat removal capacity of air cooling heat exchanger. From analysis result, it is known that inflow air velocity is the decisive factor of the heat removal capacity and predicted air velocity is lower than required air velocity. But present heat transfer model and predicted air velocity have uncertainty. So, if changed design of PAFS that has over 4.6 kW heat removal capacity in each tube, this type heat exchanger can be applied to long term cooling of the nuclear power plant

Performance assesment of solar heating and cooling systems

Energy Technology Data Exchange (ETDEWEB)

Shesho, Igor; Armenski, Slave [Faculty of Mechanical Engineering, ' Ss. Cyril and Methodius' University, Skopje (Macedonia, The Former Yugoslav Republic of); others, and

2014-07-01

Thermal performance of the solar thermal systems are estimated using numerical methods and software since the solar processes are transitient in nature been driven by time dependent forcing functions and loads. The system components are defined with mathematical relationships that describe how components function. They are based on the first principles (energy balances, mass balances, rate equations and equilibrium relationships) at one extreme or empirical curve fits to operating data from specific machines such as absorption chillers. The component models are programed, i.e. they represent written subroutines which are simultaneously solved with the executive program. In this paper for executive program is chosen TRNSYS containing library with solar thermal system component models. Validation of the TRNSYS components models is performed, i.e. the simulation results are compared with experimental measurements. Analysis is performed for solar assisted cooling system in order to determine the solar fractions and efficiencies for different collector types, areas and storage tanks. Specific indicators are derived in order to facilitate the techno-economic analysis and design of solar air-conditioning systems. (Author)

Experimental study of cooling performance of pneumatic synthetic jet with singular slot rectangular orifice

Science.gov (United States)

Yu, Roger Ho Zhen; Ismail, Mohd Azmi bin; Ramdan, Muhammad Iftishah; Mustaffa, Nur Musfirah binti

2017-03-01

Synthetic Jet generates turbulence flow in cooling the microelectronic devices. In this paper, the experiment investigation of the cooling performance of pneumatic synthetic jet with single slot rectangular orifices at low frequency motion is presented. The velocity profile at the end of the orifice was measured and used as characteristic performance of synthetic jet in the present study. Frequencies of synthetic jet and the compressed air pressure supplied to the pneumatic cylinder (1bar to 5bar) were the parameters of the flow measurement. The air velocity of the synthetic jet was measured by using anemometer air flow meter. The maximum air velocity was 0.5 m/s and it occurred at frequency motion of 8 Hz. The optimum compressed air supplied pressure of the synthetic jet study was 4 bar. The cooling performance of synthetic jet at several driven frequencies from 0 Hz to 8 Hz and heat dissipation between 2.5W and 9W were also investigate in the present study. The results showed that the Nusselt number increased and thermal resistance decreased with both frequency and Reynolds number. The lowest thermal resistance was 5.25°C/W and the highest Nusselt number was 13.39 at heat dissipation of 9W and driven frequency of 8Hz.

Legionnaires' Disease Outbreak at a Long-Term Care Facility Caused by a Cooling Tower Using an Automated Disinfection System--Ohio, 2013.

Science.gov (United States)

Quinn, Celia; Demirjian, Alicia; Watkins, Louise Francois; Tomczyk, Sara; Lucas, Claressa; Brown, Ellen; Kozak-Muiznieks, Natalia; Benitez, Alvaro; Garrison, Laurel E; Kunz, Jasen; Brewer, Scott; Eitniear, Samantha; DiOrio, Mary

2015-12-01

On July 9, 2013, an outbreak of Legionnaires' disease (LD) was identified at Long-Term Care Facility A in central Ohio. This article describes the investigation of the outbreak and identification of the outbreak source, a cooling tower using an automated biocide delivery system. In total, 39 outbreak LD cases were identified; among these, six patients died. Water samples from a cooling tower were positive for Legionella pneumophila serogroup 1, reactive to monoclonal antibody 2, with matching sequence type to a patient isolate. An electronic control system turned off cooling tower pumps during low-demand periods, preventing delivery of disinfectant by a timed-release system, and leading to amplification of Legionella in the cooling tower. Guidelines for tower maintenance should address optimal disinfection when using automated systems.

The influence and analysis of natural crosswind on cooling characteristics of the high level water collecting natural draft wet cooling tower

Science.gov (United States)

Ma, Libin; Ren, Jianxing

2018-01-01

Large capacity and super large capacity thermal power is becoming the main force of energy and power industry in our country. The performance of cooling tower is related to the water temperature of circulating water, which has an important influence on the efficiency of power plant. The natural draft counter flow wet cooling tower is the most widely used cooling tower type at present, and the high cooling tower is a new cooling tower based on the natural ventilation counter flow wet cooling tower. In this paper, for high cooling tower, the application background of high cooling tower is briefly explained, and then the structure principle of conventional cooling tower and high cooling tower are introduced, and the difference between them is simply compared. Then, the influence of crosswind on cooling performance of high cooling tower under different wind speeds is introduced in detail. Through analysis and research, wind speed, wind cooling had little impact on the performance of high cooling tower; wind velocity, wind will destroy the tower inside and outside air flow, reducing the cooling performance of high cooling tower; Wind speed, high cooling performance of cooling tower has increased, but still lower than the wind speed.

Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion

Energy Technology Data Exchange (ETDEWEB)

Cornejo, J. M.; Colombano, M.; Doménech, J.; Rodríguez, D., E-mail: danielrodriguez@ugr.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, 18071 Granada (Spain); Block, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institut Mainz, 55099 Mainz (Germany); Institut für Kernchemie, University of Mainz, 55099 Mainz (Germany); Delahaye, P. [Grand Accélérateur National d’Ions Lourds, 14000 Caen (France)

2015-10-15

A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single {sup 40}Ca{sup +} ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on {sup 40}Ca{sup +} ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

Science.gov (United States)

Micklow, Gerald J.

1996-01-01

The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.

Small high cooling power space cooler

Energy Technology Data Exchange (ETDEWEB)

Nguyen, T. V.; Raab, J.; Durand, D.; Tward, E. [Northrop Grumman Aerospace Systems Redondo Beach, Ca, 90278 (United States)

2014-01-29

The small High Efficiency pulse tube Cooler (HEC) cooler, that has been produced and flown on a number of space infrared instruments, was originally designed to provide cooling of 10 W @ 95 K. It achieved its goal with >50% margin when limited by the 180 W output ac power of its flight electronics. It has also been produced in 2 stage configurations, typically for simultaneously cooling of focal planes to temperatures as low as 35 K and optics at higher temperatures. The need for even higher cooling power in such a low mass cryocooler is motivated by the advent of large focal plane arrays. With the current availability at NGAS of much larger power cryocooler flight electronics, reliable long term operation in space with much larger cooling powers is now possible with the flight proven 4 kg HEC mechanical cooler. Even though the single stage cooler design can be re-qualified for those larger input powers without design change, we redesigned both the linear and coaxial version passive pulse tube cold heads to re-optimize them for high power cooling at temperatures above 130 K while rejecting heat to 300 K. Small changes to the regenerator packing, the re-optimization of the tuned inertance and no change to the compressor resulted in the increased performance at 150 K. The cooler operating at 290 W input power achieves 35 W@ 150 K corresponding to a specific cooling power at 150 K of 8.25 W/W and a very high specific power of 72.5 W/Kg. At these powers the cooler still maintains large stroke, thermal and current margins. In this paper we will present the measured data and the changes to this flight proven cooler that were made to achieve this increased performance.

Construction and performance tests of a secondary hydrogen gas cooling system

International Nuclear Information System (INIS)

Sanokawa, K.; Hishida, M.

1980-01-01

With the aim of a multi-purpose use of nuclear energy, such as direct steel-making, an experimental multi-purpose high-temperature gas-cooled reactor (VHTR) is now being developed by the Japan Atomic Energy Research Institute (JAERI). In order to simulate a heat exchanging system between the primary helium gas loop and the secondary reducing gas system of the VHTR, a hydrogen gas loop as a secondary cooling system of the existing helium gas loop was completed in 1977, and was successfully operated for over 2000 hours. The objectives of constructing the H 2 secondary loop were: (1) To get basic knowledge for designing, constructing and operating a high-temperature and high-pressure gas facility; (2) To perform the following tests: (a) hydrogen permeation at the He/H 2 heat exchanger (the surfaces of the heat exchanger tubes are coated by calorizing to reduce hydrogen permeation), (b) thermal performance tests of the He/H 2 heat exchanger and the H 2 /H 2 regenerative heat exchanger, (c) performance test of internal insulation, and (d) performance tests of the components such as a H 2 gas heater and gas purifiers. These tests were carried out at He gas temperature of approximately 1000 0 C, H 2 gas temperature of approximately 900 0 C and gas pressures of approximately 40 kg/cm 2 G, which are almost the same as the operating conditions of the VHTR

Temperature Field Accurate Modeling and Cooling Performance Evaluation of Direct-Drive Outer-Rotor Air-Cooling In-Wheel Motor

Directory of Open Access Journals (Sweden)

Feng Chai

2016-10-01

Full Text Available High power density outer-rotor motors commonly use water or oil cooling. A reasonable thermal design for outer-rotor air-cooling motors can effectively enhance the power density without the fluid circulating device. Research on the heat dissipation mechanism of an outer-rotor air-cooling motor can provide guidelines for the selection of the suitable cooling mode and the design of the cooling structure. This study investigates the temperature field of the motor through computational fluid dynamics (CFD and presents a method to overcome the difficulties in building an accurate temperature field model. The proposed method mainly includes two aspects: a new method for calculating the equivalent thermal conductivity (ETC of the air-gap in the laminar state and an equivalent treatment to the thermal circuit that comprises a hub, shaft, and bearings. Using an outer-rotor air-cooling in-wheel motor as an example, the temperature field of this motor is calculated numerically using the proposed method; the results are experimentally verified. The heat transfer rate (HTR of each cooling path is obtained using the numerical results and analytic formulas. The influences of the structural parameters on temperature increases and the HTR of each cooling path are analyzed. Thereafter, the overload capability of the motor is analyzed in various overload conditions.

Characteristic Evaluation on the Cooling Performance of an Electrical Air Conditioning System Using R744 for a Fuel Cell Electric Vehicle

Directory of Open Access Journals (Sweden)

Moo-Yeon Lee

2012-05-01

Full Text Available The objective of this study was to investigate the cooling performance characteristics of an electrical air conditioning system using R744 as an alternative of R-134a for a fuel cell electric vehicle. In order to analyze the cooling performance characteristics of the air conditioning system using R744 for a fuel cell electric vehicle, an electrical air conditioning system using R744 was developed and tested under various operating conditions according to both inlet air conditions of the gas cooler and evaporator and compressor speed. The cooling capacity and coefficient of performance (COP forcooling of the tested air conditioning system were up to 6.4 kW and 2.5, respectively. In addition, the electrical air conditioning system with R744 using an inverter driven compressor showed better performance than the conventional air conditioning system with R-134a under the same operating conditions. The observed cooling performance of the developed electrical air conditioning system was found to be sufficient for cooling loads under various real driving conditions for a fuel cell electric vehicle.

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...... in different climates: temperate in Copenhagen and Mediterranean in Venice. Cheap and clean heat sources (e.g. solar energy) strongly increase the attractiveness of the DDC system. For the Mediterranean climate the DDC system represents a convenient alternative to chiller-based systems in terms of energy costs...... and CO2 emissions. The electricity consumption for auxiliaries in the DDC system is higher than in the chiller-based systems. The number of commercial-size DPC units required to cover the cooling load during the whole period is high: 8 in Copenhagen and 12 in Venice....

Investigation of Stratified Thermal Storage Tank Performance for Heating and Cooling Applications

Directory of Open Access Journals (Sweden)

Azharul Karim

2018-04-01

Full Text Available A large amount of energy is consumed by heating and cooling systems to provide comfort conditions for commercial building occupants, which generally contribute to peak electricity demands. Thermal storage tanks in HVAC systems, which store heating/cooling energy in the off-peak period for use in the peak period, can be used to offset peak time energy demand. In this study, a theoretical investigation on stratified thermal storage systems is performed to determine the factors that significantly influence the thermal performance of these systems for both heating and cooling applications. Five fully-insulated storage tank geometries, using water as the storage medium, were simulated to determine the effects of water inlet velocity, tank aspect ratio and temperature difference between charging (inlet and the tank water on mixing and thermocline formation. Results indicate that thermal stratification enhances with increased temperature difference, lower inlet velocities and higher aspect ratios. It was also found that mixing increased by 303% when the temperature difference between the tank and inlet water was reduced from 80 °C to 10 °C, while decreasing the aspect ratio from 3.8 to 1.0 increased mixing by 143%. On the other hand, increasing the inlet water velocity significantly increased the storage mixing. A new theoretical relationship between the inlet water velocity and thermocline formation has been developed. It was also found that inlet flow rates can be increased, without increasing the mixing, after the formation of the thermocline.

Long-term associative learning predicts verbal short-term memory performance.

Science.gov (United States)

Jones, Gary; Macken, Bill

2018-02-01

Studies using tests such as digit span and nonword repetition have implicated short-term memory across a range of developmental domains. Such tests ostensibly assess specialized processes for the short-term manipulation and maintenance of information that are often argued to enable long-term learning. However, there is considerable evidence for an influence of long-term linguistic learning on performance in short-term memory tasks that brings into question the role of a specialized short-term memory system separate from long-term knowledge. Using natural language corpora, we show experimentally and computationally that performance on three widely used measures of short-term memory (digit span, nonword repetition, and sentence recall) can be predicted from simple associative learning operating on the linguistic environment to which a typical child may have been exposed. The findings support the broad view that short-term verbal memory performance reflects the application of long-term language knowledge to the experimental setting.

The influence of whole-body vs. torso pre-cooling on physiological strain and performance of high-intensity exercise in the heat.

Science.gov (United States)

Sleivert, G G; Cotter, J D; Roberts, W S; Febbraio, M A

2001-04-01

Little research has been reported examining the effects of pre-cooling on high-intensity exercise performance, particularly when combined with strategies to keep the working muscle warm. This study used nine active males to determine the effects of pre-cooling the torso and thighs (LC), pre-cooling the torso (ice-vest in 3 degrees C air) while keeping the thighs warm (LW), or no cooling (CON: 31 degrees C air), on physiological strain and high-intensity (45-s) exercise performance (33 degrees C, 60% rh). Furthermore, we sought to determine whether performance after pre-cooling was influenced by a short exercise warm-up. The 45-s test was performed at different (PForearm blood flow prior to exercise was also lower in LC (3.1+/-2.0 ml 100 ml tissue(-1) x min(-1)) than CON (8.2+/-2.5, P=0.01) but not LW (4.3+/-2.6, P=0.46). After an exercise warm-up, muscle temperature (Tm) was not significantly different between conditions (CON: 37.3+/-1.5, LW: 37.3+/-1.2, LC: 36.6+/-0.7 degrees C, P=0.16) but when warm-up was excluded, T(m) was lower in LC (34.5+/-1.9 degrees C, P=0.02) than in CON (37.3+/-1.0) and LW (37.1+/-0.9). Even when a warm-up was performed, torso+thigh pre-cooling decreased both peak (-3.4+/-3.8%, P=0.04) and mean power output (-4.1+/-3.8%, P=0.01) relative to the control, but this effect was markedly larger when warm-up was excluded (peak power -7.7+/-2.5%, P=0.01; mean power -7.6+/-1.2%, P=0.01). Torso-only pre-cooling did not reduce peak or mean power, either with or without warm-up. These data indicate that pre-cooling does not improve 45-s high-intensity exercise performance, and can impair performance if the working muscles are cooled. A short exercise warm-up largely removes any detrimental effects of a cold muscle on performance by increasing Tm.

Long-term prospects for the gas-cooled reactor

International Nuclear Information System (INIS)

Tan, W.P.S.

1982-01-01

Towards the second half of a fifty-year time span the market for gas-cooled reactors as sources of high temperature process heat and as highly fuel efficient electricity producers should be reasonably bright, given a fair degree of technological maturity and consequent realisation of inherent economic advantages. Declining fossil resources and increasing prices, initially in oil and gas later in open-cast coal, provide the economic impetus towards substitution of nuclear for coal heat, not only in the generally accepted processes of coal conversion and steel-making but also for oil shale pyrolysis and electrothermal aluminium smelting. Around 2010, if not sooner, the need for uranium conservation should allow the market penetration of breeders and thorium-cycle reactors for which gas cooling has a potential techno-economic edge. (author)

Long-term prospects for the gas-cooled reactor

International Nuclear Information System (INIS)

Tan, W.P.S.

1983-01-01

Towards the second half of a 50-year time span the market for gas-cooled reactors as sources of high-temperature process heat and as highly fuel-efficient electricity producers should be reasonably bright, given a fair degree of technological maturity and consequent realization of inherent economic advantages. Declining fossil resources and increasing prices, initially in oil and gas, later in open-cast coal, provide the economic impetus towards substitution of nuclear for coal heat, not only in the generally accepted processes of coal conversion and steel making but also for oil shale pyrolysis and electrothermal aluminium smelting. Around 2010, if not sooner, the need for uranium conservation should allow the market penetration of breeders and thorium-cycle reactors for which gas cooling has a potential techno-economic edge. (author)

Thermoelectric air-cooling module for electronic devices

International Nuclear Information System (INIS)

Chang, Yu-Wei; Chang, Chih-Chung; Ke, Ming-Tsun; Chen, Sih-Li

2009-01-01

This article investigates the thermoelectric air-cooling module for electronic devices. The effects of heat load of heater and input current to thermoelectric cooler are experimentally determined. A theoretical model of thermal analogy network is developed to predict the thermal performance of the thermoelectric air-cooling module. The result shows that the prediction by the model agrees with the experimental data. At a specific heat load, the thermoelectric air-cooling module reaches the best cooling performance at an optimum input current. In this study, the optimum input currents are from 6 A to 7 A at the heat loads from 20 W to 100 W. The result also demonstrates that the thermoelectric air-cooling module performs better performance at a lower heat load. The lowest total temperature difference-heat load ratio is experimentally estimated as -0.54 W K -1 at the low heat load of 20 W, while it is 0.664 W K -1 at the high heat load of 100 W. In some conditions, the thermoelectric air-cooling module performs worse than the air-cooling heat sink only. This article shows the effective operating range in which the cooling performance of the thermoelectric air-cooling module excels that of the air-cooling heat sink only.

Analysis of a solid desiccant cooling system with indirect evaporative cooling

DEFF Research Database (Denmark)

Bellemo, Lorenzo

investigates the performance of a solid desiccant cooling system implementing in-direct evaporative cooling processes. The aim is to quantify the system thermal and electrical performance for varying component dimensions and operating conditions, and to identify its range of applicability. This information...... evaporative cooler. Detailed steady state numerical models are developed and implemented in MATLAB. The models need to be accurate and require low computational effort, for analysing the internal heat and mass transfer processes, as well as carrying out repetitive design and optimization simulations......-to-air heat exchanger for enhancing cooling capacity and thermal performance. The system perfor-mance is investigated considering regeneration temperatures between 50 ºC and 90 ºC, which enable low temperature heat sources, such as solar energy or waste heat, to be used. The effects of several geometrical...

Sensitivity analysis of the thermal performance of radiant and convective terminals for cooling buildings

DEFF Research Database (Denmark)

Le Dréau, J.; Heiselberg, P.

2014-01-01

Heating and cooling terminals can be classified in two main categories: convective terminals (e.g. active chilled beam, air conditioning) and radiant terminals. The mode of heat transfer of the two emitters is different: the first one is mainly based on convection, whereas the second one is based...... conducted to determine the parameters influencing their thermal performance the most. The air change rate, the outdoor temperature and the air temperature stratification have the largest effect on the cooling need (maintaining a constant operative temperature). For air change rates higher than 0.5 ACH...

Thermal analysis of a direct evaporative cooling system enhancement with desiccant dehumidification for vehicular air conditioning

International Nuclear Information System (INIS)

Alahmer, Ali

2016-01-01

Highlights: • Thermal analysis was conducted to design a desiccant evaporative cooling system for vehicular air conditioning. • EC is more efficient than the conventional air conditioning when the gasoline price is more than 0.34 $/liter. • Drawbacks of evaporative cooler of increased weight and reduced COP. • A rotary desiccant dehumidifier with generation was combined with evaporative cooling to be more efficient. - Abstract: This manuscript analyzes the sub-systems of evaporative cooler (EC) combined with desiccant dehumidification and regeneration for automotive air conditioning purpose. The thermodynamic and psychometric analysis was conducted to design all evaporative cooling system components in terms of desiccant selection, regeneration process, compact heat exchanger and evaporative cooler. Moreover, the effect of the desiccant, heat exchanger and evaporative performances on the mass flow rate and water sprayed required for evaporative cooling system was investigated. The results show that the theoretical evaporative cooling design will achieve two main objectives: lower fuel consumption and less environmental pollutants. However, it has the two drawbacks in terms of increased weight and reduces the coefficient of performance (COP). The main remark is that evaporating cooling system is more efficient than the conventional air conditioning when the gasoline price is more than 0.34 $/liter.

A review of photovoltaic cells cooling techniques

Science.gov (United States)

Zubeer, Swar A.; Mohammed, H. A.; Ilkan, Mustafa

2017-11-01

This paper highlights different cooling techniques to reduce the operating temperature of the PV cells. This review paper focuses on the improvement of the performance of the small domestic use PV systems by keeping the temperature of the cells as low as possible and uniform. Different cooling techniques have been investigated experimentally and numerically the impact of the operating temperature of the cells on the electrical and thermal performance of the PV systems. The advantages and disadvantages of ribbed wall heat sink cooling, array air duct cooling installed beneath the PV panel, water spray cooling technique and back surface water cooling are examined in this paper to identify their effective impact on the PV panel performance. It was identified that the water spray cooling system has a proper impact on the PV panel performance. So the water cooling is one way to enhance the electrical efficiency of the PV panel.

LOFA analyses for the water and helium cooled SEAFP reactors

International Nuclear Information System (INIS)

Sponton, L.; Sjoeberg, A.; Nordlinder, S.

2001-01-01

This study was performed in the frame of the European long-term fusion safety programme 1999 (SEAFP99). Loss of flow accidents (LOFA) have been studied for two cases, first for a helium cooled reactor with advanced dual-coolant (DUAL) blanket at 100% nominal power. The second case applies to a water-cooled reactor at 20% nominal power. Both transients were simulated with the code MELCOR 1.8.4. The results for the helium cooled reactor show that with a natural circulation flow of helium after the pump stops, the first wall temperature will stay below the temperature for excepted failure of the construction material. For the water cooled reactor, the results show that the pressurizer set point for its liquid volumetric inventory is reached before the plasma facing components attain a critical temperature. The pressurizer set point will induce a plasma shutdown

Optimization design of solar enhanced natural draft dry cooling tower

International Nuclear Information System (INIS)

Zou, Zheng; Guan, Zhiqiang; Gurgenci, Hal

2013-01-01

Highlights: • We proposed a cost model for solar enhanced natural draft dry cooling tower. • We proposed an optimization scheme for this new cooling system. • We optimally designed one for a 50 MW EGS geothermal plant as a demonstration. • Results proved its economic advantages for EGS geothermal application. - Abstract: This paper proposed an optimization scheme for solar enhanced natural draft dry cooling tower design, in which a detailed cost model was proposed including capital, labour, maintenance and operation costs of each component. Based on the developed cost model, the optimal design option can be identified in terms of the relatively lower annual cost and the relatively higher total extra income over the Solar Enhanced Natural Draft Dry Cooling Tower (SENDDCT) lifetime. As a case study, a SENDDCT was optimally designed to meet the cooling demand for a 50 MW geothermal power plant with Engineered Geothermal System (EGS) technology. The results showed that the optimized SENDDCT not only has better cooling performance during the daytime but also is a cost effective option for EGS geothermal power plants

Performance of a conduction-cooled high-temperature superconducting bearing

International Nuclear Information System (INIS)

Strasik, M.; Hull, J.R.; Johnson, P.E.; Mittleider, J.; McCrary, K.E.; McIver, C.R.; Day, A.C.

2008-01-01

We report rotational loss measurements for a high-temperature superconducting (HTS) bearing whose cooling consists of a thermal conduction path to the cold head of a cryocooler. Losses have been measured for rotational rates up to 14,500 rpm at different HTS temperatures. The rotational losses decrease with decreasing HTS temperature. For temperatures that can be obtained in a liquid-nitrogen thermosiphon system, at a given speed and gap, the loss of the conduction-cooled HTS bearing is not significantly higher than the loss of a nearly identical HTS bearing cooled by flowing nitrogen from the thermosiphon

Modeling and characteristics analysis of hybrid cooling-tower-solar-chimney system

International Nuclear Information System (INIS)

Zou, Zheng; He, Suoying

2015-01-01

Highlights: • A 3-D model for hybrid cooling-tower-solar-chimney system is developed. • The inclusion of heat exchangers into solar chimney boosts the power output. • The huge jump in power output is at the expense of heat dissipation capacity. • The heat exchanger as second heat source has greater impact on system performance. - Abstract: The hybrid cooling-tower-solar-chimney system (HCTSC), combining solar chimney with natural draft dry cooling tower, generates electricity and dissipates waste heat for the coupled geothermal power plant simultaneously. Based on a developed 3-D model, performance comparisons between the HCTSC system, solar chimney and natural draft dry cooling tower were performed in terms of power output of turbine and heat dissipation capacity. Results show that compared to the traditional solar chimney with similar geometric dimensions, HCTSC system can achieve over 20 times increase in the power output of turbine. However, this huge jump in power output is at the expense of heat dissipation capacity, which may lead to the malfunction of the coupled thermal power plant. By increasing the heat transfer area of the heat exchanger, the HCTSC system can manage to recover its heat dissipation capacity

Conceptual development of a building-integrated photovoltaic–radiative cooling system and preliminary performance analysis in Eastern China

International Nuclear Information System (INIS)

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

2017-01-01

Highlights: •A specific spectral characteristic for both PV and RC was proposed. •The PV/RC hybrid system based on spectral characteristic is original. •A thermal model of the system was established and the performance was analyzed. •The performance comparison with the conventional PV system was conducted. •The system shows considerable performance for both PV and RC. -- Abstract: Building-integrated photovoltaic/thermal (BIPV/T) technology has been receiving considerable research attention because of its ability to generate electricity and thermal energy simultaneously. However, space cooling is crucial for buildings in hot regions where space heating is of little use. This study proposed a building-integrated photovoltaic–radiative cooling system (BIPV–RC) that can generate electricity via photovoltaic (PV) conversion during daytime and generate cooling energy via radiative cooling (RC) during nighttime to satisfy the demand in such areas. The selective plate, which is the main component of the BIPV–RC system, exhibits high spectral absorptivity (emissivity) in the PV conversion band of crystalline silicon solar cells and in the atmospheric window band (i.e., 0.3–1.1 μm and 8–13 μm), as well as low spectral absorptivity (emissivity) in other bands. A quasi-steady-state mathematical model was built, and its performance under realistic ambient conditions was analyzed. The electrical efficiencies of the BIPV–RC and conventional BIPV systems were then compared under different solar radiations. Comparison results show that the annual electricity production and cooling energy gain of the BIPV–RC system in Hefei reached 156.74 kW h m −2 (equivalent to 564.26 MJ m −2 ) and 579.91 MJ m −2 , respectively. The total electricity production and cooling energy gain of this system are 96.96% higher than those of the BIPV system. Parametric studies show that the precipitable water vapor amount has remarkable effects on the nocturnal RC performance

Boost Converter Fed High Performance BLDC Drive for Solar PV Array Powered Air Cooling System

Directory of Open Access Journals (Sweden)

Shobha Rani Depuru

2017-01-01

Full Text Available This paper proposes the utilization of a DC-DC boost converter as a mediator between a Solar Photovoltaic (SPV array and the Voltage Source Inverters (VSI in an SPV array powered air cooling system to attain maximum efficiency. The boost converter, over the various common DC-DC converters, offers many advantages in SPV based applications. Further, two Brushless DC (BLDC motors are employed in the proposed air cooling system: one to run the centrifugal water pump and the other to run a fan-blower. Employing a BLDC motor is found to be the best option because of its top efficiency, supreme reliability and better performance over a wide range of speeds. The air cooling system is developed and simulated using the MATLAB/Simulink environment considering the steady state variation in the solar irradiance. Further, the efficiency of BLDC drive system is compared with a conventional Permanent Magnet DC (PMDC motor drive system and from the simulated results it is found that the proposed system performs better.

Cooling performance assessment of horizontal earth tube system and effect on planting in tropical greenhouse

International Nuclear Information System (INIS)

Mongkon, S.; Thepa, S.; Namprakai, P.; Pratinthong, N.

2014-01-01

Graphical abstract: - Highlights: • The cooling ability of HETS is studied for planting in tropical greenhouse. • The effective of system was moderate with COP more than 2.0. • Increasing diameter and air velocity increase COP more than other parameters. • The plant growth with HETS was significantly better than no-HETS plant. - Abstract: The benefit of geothermal energy is used by the horizontal earth tube system (HETS); which is not prevalent in tropical climate. This study evaluated geothermal cooling ability and parameters studied in Thailand by mathematical model. The measurement of the effect on plant cultivation was carried out in two identical greenhouses with 30 m 2 of greenhouse volume. The HETS supplied cooled air to the model greenhouse (MGH), and the plant growth results were compared to the growth results of a conventional greenhouse (CGH). The prediction demonstrated that the coefficient of performance (COP) in clear sky day would be more than 2.0 while in the experiment it was found to be moderately lower. The parameters study could be useful for implementation of a system for maximum performance. Two plants Dahlias and head lettuce were grown satisfactory. The qualities of the plants with the HETS were better than the non-cooled plants. In addition, the quality of production was affected by variations of microclimate in the greenhouses and solar intensity throughout the cultivation period

Cooled perch effects on performance and well-being traits in caged White Leghorn hens.

Science.gov (United States)

Hu, J Y; Hester, P Y; Makagon, M M; Vezzoli, G; Gates, R S; Xiong, Y J; Cheng, H W

2016-12-01

We assessed the effects of chilled water cooling perches on hen performance and physiological and behavioral parameters under "natural" high temperatures during the 2013 summer with a 4-hour acute heating episode. White Leghorns at 16 wk of age (N = 162) were randomly assigned to 18 cages (n = 9) arranged into 3 units. Each unit was assigned to one of the 3 treatments through 32 wk of age: 1) cooled perches, 2) air perches, and 3) no perches. Chilled water (10°C) was circulated through the cooled perches when cage ambient temperature exceeded 25°C. At the age of 27.6 wk, hens were subjected to a 4-hour acute heating episode of 33.3°C and plasma corticosterone was determined within 2 hours. Egg production was recorded daily. Feed intake and egg and shell quality were measured at 5-week intervals. Feather condition, foot health, adrenal and liver weights, plasma corticosterone, and heat shock protein 70 mRNA were determined at the end of the study at 32 wk of age. The proportion of hens per cage perching, feeding, drinking, panting, and wing spreading was evaluated over one d every 5 wks and on the d of acute heat stress. There were no treatment effects on the measured physiological and production traits except for nail length. Nails were shorter for cooled perch hens than control (P = 0.002) but not air perch hens. Panting and wing spread were observed only on the day of acute heat stress. The onset of both behaviors was delayed for cooled perch hens, and they perched more than air perch hens following acute heat stress (P = 0.001) and at the age 21.4 wk (P = 0.023). Cooled perch hens drank less than control (P = 0.019) but not air perch hens at the age 21.4 wk. These results indicate that thermally cooled perches reduced thermoregulatory behaviors during acute heat stress, but did not affect their performance and physiological parameters under the ambient temperature imposed during this study. Published by Oxford University Press on behalf of

A simpler, safer, higher performance cooling system arrangement for water cooled divertors

International Nuclear Information System (INIS)

Carelli, M.D.; Kothmann, R.E.; Green, L.; Zhan, N.J.; Stefani, F.; Roidt, R.M.

1994-01-01

A cooling system arrangement is presented which is specifically designed for high heat flux water cooled divertors. The motivation behind the proposed open-quotes unichannelclose quotes configuration is to provide maximum safety; this design eliminates flow instabilities liable to occur in parallel channel designs, it eliminates total blockage, it promotes cross flow to counteract the effects of partial blockage and/or local hot spots, and it is much more tolerant to the effects of debonding between the beryllium armor and the copper substrate. Added degrees of freedom allow optimization of the design, including the possibility of operating at very high heat transfer coefficients associated with nucleate boiling, while at the same time providing ample margin against departure from nucleate boiling. Projected pressure drop, pumping power, and maximum operating temperatures are lower than for conventional parallel channel designs

A review of photovoltaic cells cooling techniques

Directory of Open Access Journals (Sweden)

Zubeer Swar A.

2017-01-01

Full Text Available This paper highlights different cooling techniques to reduce the operating temperature of the PV cells. This review paper focuses on the improvement of the performance of the small domestic use PV systems by keeping the temperature of the cells as low as possible and uniform. Different cooling techniques have been investigated experimentally and numerically the impact of the operating temperature of the cells on the electrical and thermal performance of the PV systems. The advantages and disadvantages of ribbed wall heat sink cooling, array air duct cooling installed beneath the PV panel, water spray cooling technique and back surface water cooling are examined in this paper to identify their effective impact on the PV panel performance. It was identified that the water spray cooling system has a proper impact on the PV panel performance. So the water cooling is one way to enhance the electrical efficiency of the PV panel.

Influence of molybdenum content on transformation behavior of high performance bridge steel during continuous cooling

International Nuclear Information System (INIS)

Chen, Jun; Tang, Shuai; Liu, Zhenyu; Wang, Guodong

2013-01-01

Highlights: ► The bainite transformation field was refined. ► The empirical equation to estimate the GF s was established. ► Transformation behavior was studied with serially increasing Mo addition. ► The molybdenum content can be lowered as the cooling rate is increased. ► GF transformation field is also shifted to right by increasing Mo content. - Abstract: The continuous-cooling-transformation (CCT) diagrams of high performance bridge steel with different molybdenum content were plotted by means of a combined method of dilatometry and metallography. The results show that the molybdenum addition of 0.17 wt% does not noticeably alter the transformation behavior, whereas 0.38 wt% significantly. In addition, the molybdenum addition of 0.38 wt% completely eliminates the formation of polygonal ferrite (PF) and significantly lower the granular ferrite (GF) transformation starting temperatures throughout the range of cooling rates studied. At lower cooling rates, with the increase of the molybdenum content, the martensite/austenite (M/A) constituents are noticeably refined, whereas the effects are not obvious at higher cooling rates. Moreover, the molybdenum addition of 0.38 wt% can significantly increase the Vickers hardness, but the Vickers hardness increments (by comparison of Mo-0.17wt% steel and Mo-0.38wt% steel) are sharply reduced at the cooling rate of 30 °C/s, indicating that at higher cooling rate, the molybdenum usage can be saved and the higher strengthen can be also gained. It could be found the GF transformation starting temperature is linear with the cooling rate. The empirical equation was established to calculate GF transformation starting temperatures, and the calculated values are in good agreement with measured ones

Thermo-Elastic Analysis of Internally Cooled Structures Using a Higher Order Theory

Science.gov (United States)

Arnold, Steven M.; Bednarcyk, Brett A.; Aboudi, Jacob

2001-01-01

This paper presents the results of a study on the thermomechanical behavior of internally cooled silicon nitride structures. Silicon nitride is under consideration for elevated temperature aerospace engine applications. and techniques for lowering the operating temperature of structures composed of this material are under development. Lowering the operating temperature provides a large payoff in terms of fatigue life and may be accomplished through the use of thermal barrier coatings (TBC's) and the novel concept of included cooling channels. Herein, an in-depth study is performed on the behavior of a flame-impinged silicon nitride plate with a TBC and internal channels cooled by forced air. The analysis is performed using the higher order theory for functionally graded materials (HOTFGM), which has been developed through NASA Glenn Research Center funding over the past several years. HOTFGM was chosen over the traditional finite element approach as a prelude to an examination of functionally graded silicon nitride structures for which HOTFGM is ideally suited. To accommodate the analysis requirement% of the internally cooled plate problem, two crucial enhancements were made to the two-dimensional Cartesian-based version of HOTFGM. namely, incorporation of internal boundary capabilities and incorporation of convective boundary conditions. Results indicate the viability and large benefits of cooling the plate via forced air through cooling channels. Furthermore, cooling can positively impact the stress and displacement fields present in the plate, yielding an additional payoff in terms of fatigue life. Finally, a spin-off capability resulted from inclusion of internal boundaries within HOTFGM; the ability to simulate the thermo-elastic response of structures with curved surfaces. This new capability is demonstrated, and through comparison with an analytical solution, shown to be viable and accurate.

Performance of materials in the component cooling water systems of pressurized water reactors

International Nuclear Information System (INIS)

Lee, B.S.

1993-01-01

The component cooling water (CCW) system provides cooling water to several important loads throughout the plant under all operating conditions. An aging assessment CCW systems in pressurized water reactors (PWRs) was conducted as part of Nuclear Plant Aging Research Program (NPAR) instituted by the US Nuclear Regulatory Commission. This paper presents some of the results on the performances of materials in respect of their application in CCW Systems. All the CCW system failures reported to the Nuclear Plant Reliability Data System (NPRDS) from January 1988 to June 1990 were reviewed; it is concluded that three of the main contributors to CCW system failures are valves, pumps, and heat exchangers. This study identified the modes and causes of failure for these components; most of the causes for the aging-related failures could be related to the performance of materials. Also, in this paper the materials used for these components are reviewed, and there aging mechanisms under CCW system conditions are discussed

The design and performance of a water cooling system for a prototype coupled cavity linear particle accelerator for the spallation neutron source

International Nuclear Information System (INIS)

Bernardin, John D.; Ammerman, Curtt N.; Hopkins, Steve M.

2002-01-01

The Spallation Neutron Source (SNS) is a facility being designed for scientific and industrial research and development. The SNS will generate and employ neutrons as a research tool in a variety of disciplines including biology, material science, superconductivity, chemistry, etc. The neutrons will be produced by bombarding a heavy metal target with a high-energy beam of protons, generated and accelerated with a linear particle accelerator, or linac. The low energy end of the linac consists of, in part, a multi-cell copper structure termed a coupled cavity linac (CCL). The CCL is responsible for accelerating the protons from an energy of 87 MeV, to 185 MeV. Acceleration of the charged protons is achieved by the use of large electrical field gradients established within specially designed contoured cavities of the CCL. While a large amount of the electrical energy is used to accelerate the protons, approximately 60-80% of this electrical energy is dissipated in the CCL's copper structure. To maintain an acceptable operating temperature, as well as minimize thermal stresses and maintain desired contours of the accelerator cavities, the electrical waste heat must be removed from the CCL structure. This is done using specially designed water cooling passages within the linac's copper structure. Cooling water is supplied to these cooling passages by a complex water cooling and temperature control system. This paper discusses the design, analysis, and testing of a water cooling system for a prototype CCL. First, the design concept and method of water temperature control is discussed. Second, the layout of the prototype water cooling system, including the selection of plumbing components, instrumentation, as well as controller hardware and software is presented. Next, the development of a numerical network model used to size the pump, heat exchanger, and plumbing equipment, is discussed. Finally, empirical pressure, flow rate, and temperature data from the prototype CCL

An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling

International Nuclear Information System (INIS)

Ozgener, Leyla; Ozgener, Onder

2010-01-01

The present study highlights the exergetic performance characteristics of an underground air tunnel for greenhouse cooling with a 47 m horizontal, 56 cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Underground air tunnel systems, also known as earth-to-air heat exchangers, are recognized to be outstanding heating, cooling and air heating systems. On the other hand, they have not been used yet in the Turkish market. Greenhouses also have important economical potential in Turkey's agricultural sector. Greenhouses should be cooled during the summer or hot days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of underground air tunnels with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The exergy transports between the components and the destructions in each of the components of the system are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The daily maximum cooling coefficient of performances (COP) values for the system are also obtained to be 15.8. The total average COP in the experimental period is found to be 10.09. The system COP was calculated based on the amount of cooling produced by the air tunnel and the amount of power required to move the air through the tunnel, while the exergetic efficiency of the air tunnel is found to be in a range among 57.8-63.2%. The overall exergy efficiency value for the system on a product/fuel basis is found to be 60.7%. (author)

Economic performance optimization of an absorption cooling system under uncertainty

International Nuclear Information System (INIS)

Gebreslassie, Berhane H.; Guillen-Gosalbez, Gonzalo; Jimenez, Laureano; Boer, Dieter

2009-01-01

Many of the strategies devised so far to address the optimization of energy systems are deterministic approaches that rely on estimated data. However, in real world applications there are many sources of uncertainty that introduce variability into the decision-making problem. Within this general context, we propose a novel approach to address the design of absorption cooling systems under uncertainty in the energy cost. As opposed to other approaches that optimize the expected performance of the system as a single objective, in our method the design task is formulated as a stochastic bi-criteria non-linear optimization problem that simultaneously accounts for the minimization of the expected total cost and the financial risk associated with the investment. The latter criterion is measured by the downside risk, which avoids the need to define binary variables thus improving the computational performance of the model. The capabilities of the proposed modeling framework and solution strategy are illustrated in a case study problem that addresses the design of a typical absorption cooling system. Numerical results demonstrate that the method presented allows to manage the risk level effectively by varying the area of the heat exchangers of the absorption cycle. Specifically, our strategy allows identifying the optimal values of the operating and design variables of the cycle that make it less sensitive to fluctuations in the energy price, thus improving its robustness in the face of uncertainty.

Short-term heat acclimation improves the determinants of endurance performance and 5-km running performance in the heat.

Science.gov (United States)

James, Carl A; Richardson, Alan J; Watt, Peter W; Willmott, Ashley G B; Gibson, Oliver R; Maxwell, Neil S

2017-03-01

This study investigated the effect of 5 days of controlled short-term heat acclimation (STHA) on the determinants of endurance performance and 5-km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W·kg -1 ), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training. STHA reduced resting (p = 0.01) and exercising (p = 0.04) core temperature alongside a smaller change in thermal sensation (p = 0.04). Both groups improved the lactate threshold (LT, p = 0.021), lactate turnpoint (LTP, p = 0.005) and velocity at maximal oxygen consumption (vV̇O 2max ; p = 0.031) similarly. Statistical differences between training methods were observed in TT performance (STHA, -6.2(5.5)%; CON, -0.6(1.7)%, p = 0.029) and total running time during the GXT (STHA, +20.8(12.7)%; CON, +9.8(1.2)%, p = 0.006). There were large mean differences in change in maximal oxygen consumption between STHA +4.0(2.2) mL·kg -1 ·min -1 (7.3(4.0)%) and CON +1.9(3.7) mL·kg -1 ·min -1 (3.8(7.2)%). Running economy (RE) deteriorated following both training programmes (p = 0.008). Similarly, RE was impaired in the cool GXT, relative to the hot GXT (p = 0.004). STHA improved endurance running performance in comparison with work-matched normothermic training, despite equality of adaptation for typical determinants of performance (LT, LTP, vV̇O 2max ). Accordingly, these data highlight the ergogenic effect of STHA, potentially via greater improvements in maximal oxygen consumption and specific thermoregulatory and associated thermal perception adaptations absent in normothermic training.

Cool-down performance of CICC superconducting coils for the CHMFL

Science.gov (United States)

Xie, Y.; Li, J.; Ouyang, Z. R.

2017-10-01

A hybrid magnet composed of a water-cooled magnet and a superconducting magnet was developed at the High Magnetic Field Laboratory of the Chinese Academy of Sciences. The superconducting coils made of Nb3Sn CICC were cooled by the forced flow of supercritical helium at 4.5 K. The paper presents the cryogenic system framework, and reports the characteristics of the supercritical helium in a cable-in-conduit conductor (CICC), including the friction factor change during the cooling process, the heat transfer coefficient from 4.6 K to 6.8 K, and the helium mass flow rate distribution. After the 23-day cooling process, the temperature reached 4.5 K. The operation process was introduced in the paper.

Performance of a compact solar absorption cooling system

International Nuclear Information System (INIS)

Mulyanef; Kamaruzzaman Sopian

2006-01-01

This paper describes the performance of a compact solar absorption system. Purpose of compact solar is collector, generator and condenser in one unit. At present, two types of absorption cooling systems are marketed: the lithium bromide-water system and the ammonia-water system. In the lithium bromide-water system, water vapor is the refrigerant and ammonia water system where ammonia is the refrigerant. In addition, the ammonia-water system requires higher generator temperature 120 o C to 150 o C than a flat-plate solar collector can provide without special techniques. The lithium bromide-water system operates satisfactorily at a generator temperature of 75 o C to 100 o C, achievable by a flat-plate collector. The lithium bromide-water system also has a higher COP than the ammonia-water system. The disadvantage of the lithium bromide-water systems is that the evaporators cannot operate at temperature below 0 o C since the refrigerant is water. The Coefficient of Performance (COP) system is 0.62 and the concentration of LiBr-H 2 O is 50%

An experimental investigation on air-side performances of finned tube heat exchangers for indirect air-cooling tower

Directory of Open Access Journals (Sweden)

Du Xueping

2014-01-01

Full Text Available A tremendous quantity of water can be saved if the air cooling system is used, comparing with the ordinary water-cooling technology. In this study, two kinds of finned tube heat exchangers in an indirect air-cooling tower are experimentally studied, which are a plain finned oval-tube heat exchanger and a wavy-finned flat-tube heat exchanger in a cross flow of air. Four different air inlet angles (90°, 60 °, 45°, and 30° are tested separately to obtain the heat transfer and resistance performance. Then the air-side experimental correlations of the Nusselt number and friction factor are acquired. The comprehensive heat transfer performances for two finned tube heat exchangers under four air inlet angles are compared. For the plain finned oval-tube heat exchanger, the vertical angle (90° has the worst performance while 45° and 30° has the best performance at small ReDc and at large ReDc, respectively. For the wavy-finned flat-tube heat exchanger, the worst performance occurred at 60°, while the best performance occurred at 45° and 90° at small ReDc and at large ReDc, respectively. From the comparative results, it can be found that the air inlet angle has completely different effects on the comprehensive heat transfer performance for the heat exchangers with different structures.

Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation

Science.gov (United States)

Namkoong, D.

1976-01-01

A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation

Science.gov (United States)

Namkoong, D.

1976-01-01

A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

Influence of Cooling Condition on the Performance of Grinding Hardened Layer in Grind-hardening

Science.gov (United States)

Wang, G. C.; Chen, J.; Xu, G. Y.; Li, X.

2018-02-01

45# steel was grinded and hardened on a surface grinding machine to study the effect of three different cooling media, including emulsion, dry air and liquid nitrogen, on the microstructure and properties of the hardened layer. The results show that the microstructure of material surface hardened with emulsion is pearlite and no hardened layer. The surface roughness is small and the residual stress is compressive stress. With cooling condition of liquid nitrogen and dry air, the specimen surface are hardened, the organization is martensite, the surface roughness is also not changed, but high hardness of hardened layer and surface compressive stress were obtained when grinding using liquid nitrogen. The deeper hardened layer grinded with dry air was obtained and surface residual stress is tensile stress. This study provides an experimental basis for choosing the appropriate cooling mode to effectively control the performance of grinding hardened layer.

Comparative performance analysis of ice plant test rig with TiO2-R-134a nano refrigerant and evaporative cooled condenser

Directory of Open Access Journals (Sweden)

Amrat Kumar Dhamneya

2018-03-01

Full Text Available The nanoparticle is used in chillers for increasing system performance. The increasing concentration of nanoparticles (TiO2 in refrigerant increases the performances of the system due decreasing compressor work done and enhance heat transfer rate. For hot and dry climate condition, performances of air-cooled condenser minimize, and C. O. P. decreases extensively in chillers due to heat transfer rate decreases in the condenser. In the condenser, nano-refrigerants are not cool at the desired level, and the system was faulty. These drawbacks of the nano-particles mixed refrigerator have promoted the research and improving heat rejection rate in the condenser. In this article, vapour compression refrigeration system coupled with evaporative cooling pad, and nano-refrigerant, for improving the performance of the system in hot & dry weather is proposed and compared experimentally. Combined evaporative cooling system and ice plant test rig have been proposed for the appropriate heat rejection offered in the condenser due to a faulty system run at high pressure. The experimental investigations revealed that the performance characteristics of the evaporatively-cooled condenser are significantly enhanced. Maximum C.O.P. increases by about 51% in the hot and dry climate condition than the normal system.

Construction and performance testing of a secondary cooling system with hydrogen gas (I)

International Nuclear Information System (INIS)

Hishida, M.; Nekoya, S.; Takizuka, T.; Emori, K.; Ogawa, M.; Ouchi, M.; Okamoto, Y.; Sanokawa, K.; Nakano, T.; Hagiwara, T.

1979-08-01

An experimental multi-purpose High-Temperature Gas Cooled Reactor (VHTR) which is supposed to be used for a direct steel-making is now being developed in JAeRI. In order to simulate the heat exchanging system between the primary helium gas and the secondary reducing gas system of VHTR, a hydrogen gas loop was constructed as a secondary cooling system of the helium gas loop. The maximum temperature and the maximum pressure of the hydrogen gas are 900 degrees C and 42 kg/cm 2 x G respectively. The construction of the hydrogen gas loop was completed in January, 1977, and was successfully operated for 1.000 h. Various performance tests, such as the hydrogen permeation test of a He/H2 heat exchanger and the thermal performance test of heat exchangers, were made. Especially, it was proved that hydrogen permeation rate through the heat exchanger was reduced to 1/30 to approximately 1/50 by a method of calorized coating, and the coating was stable during 1.000 h's operation. It was also stable against the temperature changes. This report describes the outline of the facility and performance of the components. (orig.) [de

Thermal performance measurements on ultimate heat sinks--cooling ponds

International Nuclear Information System (INIS)

Hadlock, R.K.; Abbey, O.B.

1977-12-01

The primary objective of the studies described is to obtain the requisite data, with respect to modeling requirements, to characterize thermal performance of heat sinks for nuclear facilities existing at elevated water temperatures in result of experiencing a genuinely large heat load and responding to meteorological influence. The data should reflect thermal performance for combinations leading to worst-case meteorological influence. A geothermal water retention basin has been chosen as the site for the first measurement program and data have been obtained in the first of several experiments scheduled to be performed there. These data illustrate the thermal and water budgets during episodes of cooling from an initially high pond water bulk temperature. Monitoring proceeded while the pond experienced only meteorological and seepage influence. The data are discussed and are presented as a data volume which may be used for calculation purposes. Suggestions for future measurement programs are stated with the intent to maintain and improve relevance to nuclear ultimate heat sinks while continuing to examine the performance of the analog geothermal pond. It is further suggested that the geothermal pond, with some modification, may be a suitable site for spray pond measurements

Unit thermal performance of atmospheric spray cooling systems

International Nuclear Information System (INIS)

Porter, R.W.; Jain, M.; Chaturvedi, S.K.

1980-01-01

Thermal performance of an open atmospheric spray pond or canal depends on the direct-contact evaporative cooling of an individual spray unit (spray nozzle or module) and the interference caused by local heating and humidification. Droplet parameters may be combined into a dimensionless group, number of transfer units (NTU) or equivalent, whereas large-scale air-vapor dynamics determine interference through the local wet-bulb temperature. Quantity NTU were implied from field experiments for a floating module used in steam-condenser spray canals. Previous data were available for a fixed-pipe nozzle assembly used in spray ponds. Quantity NTU were also predicted using the Ranz-Marshall correlations with the Sauter-mean diameter used as the characteristic length. Good agreement with experiments was shown for diameters of 1--1.1 cm (module) and 1.9 mm

Core cooling systems

International Nuclear Information System (INIS)

Hoeppner, G.

1980-01-01

The reactor cooling system transports the heat liberated in the reactor core to the component - heat exchanger, steam generator or turbine - where the energy is removed. This basic task can be performed with a variety of coolants circulating in appropriately designed cooling systems. The choice of any one system is governed by principles of economics and natural policies, the design is determined by the laws of nuclear physics, thermal-hydraulics and by the requirement of reliability and public safety. PWR- and BWR- reactors today generate the bulk of nuclear energy. Their primary cooling systems are discussed under the following aspects: 1. General design, nuclear physics constraints, energy transfer, hydraulics, thermodynamics. 2. Design and performance under conditions of steady state and mild transients; control systems. 3. Design and performance under conditions of severe transients and loss of coolant accidents; safety systems. (orig./RW)

Gas-cooled reactors

International Nuclear Information System (INIS)

Vakilian, M.

1977-05-01

The present study is the second part of a general survey of Gas Cooled Reactors (GCRs). In this part, the course of development, overall performance and present development status of High Temperature Gas Cooled Reactors (HTCRs) and advances of HTGR systems are reviewed. (author)

Simulation of long-term cooling in the VVER-640 power plant after a large break LOKA on the PACTEL facility

International Nuclear Information System (INIS)

Banati, J.

2000-01-01

The present report gives a short introduction to the safety features of the new Russian VVER-640 reactor design. In order to analyze the complex thermal hydraulic phenomena during long-term cooling after a large-break LOCA, experiments will be carried out in the PACTEL facility. For preparation, pre-test calculations were performed using the RELAPS/MOD3.2 computer code. The main part of the report discusses the results obtained by the program. The structure and options used in the input deck, as well as the efforts of code application to the simulation of proposed experiments are reviewed. A short sensitivity study is provided on the calculated results. Finally, conclusions are drawn for the code capabilities to represent the expectable trends in the upcoming tests. (orig.)

Experimental diagnosis of the influence of operational variables on the performance of a solar absorption cooling system

International Nuclear Information System (INIS)

Venegas, M.; Rodriguez-Hidalgo, M.C.; Salgado, R.; Lecuona, A.; Rodriguez, P.; Gutierrez, G.

2011-01-01

This paper presents the analysis of the performance of a solar cooling facility along one summer season using a commercial single-effect water-lithium bromide absorption chiller aiming at domestic applications. The facility works only with solar energy using flat plate collectors and it is located at Universidad Carlos III de Madrid, Spain. The statistical analysis performed with the gathered data shows the influence of five daily operational variables on the system performance. These variables are solar energy received along the day (H) and the average values, along the operating period of the solar cooling facility (from sunrise to the end of the cold-water production), of the ambient temperature (T -bar ), the wind velocity magnitude (V), the wind direction (θ) and the relative humidity (RH). First order correlation functions are given. The analysis of the data allows concluding that the most influential variables on the daily cooling energy produced and the daily averaged solar COP are H, V and θ. The period length of cold-water production is determined mainly by H and T -bar .

Experimental diagnosis of the influence of operational variables on the performance of a solar absorption cooling system

Energy Technology Data Exchange (ETDEWEB)

Venegas, M.; Rodriguez-Hidalgo, M.C.; Lecuona, A.; Rodriguez, P.; Gutierrez, G. [Dpto. Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain); Salgado, R. [Dpto. Ingenieria Mecanica, Universidad Interamericana de Puerto Rico, Recinto de Bayamon, 500 Carretera Dr. John Will Harris Bayamon, PR 00957-6257 (United States)

2011-04-15

This paper presents the analysis of the performance of a solar cooling facility along one summer season using a commercial single-effect water-lithium bromide absorption chiller aiming at domestic applications. The facility works only with solar energy using flat plate collectors and it is located at Universidad Carlos III de Madrid, Spain. The statistical analysis performed with the gathered data shows the influence of five daily operational variables on the system performance. These variables are solar energy received along the day (H) and the average values, along the operating period of the solar cooling facility (from sunrise to the end of the cold-water production), of the ambient temperature (anti T), the wind velocity magnitude (V), the wind direction ({theta}) and the relative humidity (RH). First order correlation functions are given. The analysis of the data allows concluding that the most influential variables on the daily cooling energy produced and the daily averaged solar COP are H, V and {theta}. The period length of cold-water production is determined mainly by H and anti T. (author)

Simulation and performance enhancement of the air cooling system in a DC/AC power converter station

Energy Technology Data Exchange (ETDEWEB)

Lozowy, R.; El-Shaboury, A.; Soliman, H.; Ormiston, S. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Mechanical and Manufacturing Engineering

2010-07-01

This study analyzed the flow structure and heat transfer in a large 3-dimensional domain with turbulence, mixed convection, an impinging jet, and flow over heated blocks. The objective was to better understand turbulent mixed-convection cooling of heat-generating bodies in 3-dimensional enclosures, which is important to industry. The cooling of 2 thyristor valve halls was simulated. Each valve hall housed 3 towers that contained electronics used in DC/AC power conversion. The simulation results included the magnitudes of the net air flows for all the inter-block gaps and the maximum temperature in each gap. A parametric study was also performed to investigate the effects of the air inlet location, size and aspect ratio. The effects of the air injection angle on cooling effectiveness was also examined. The study showed that for fixed inlet mass flow rate, significant improvement in the cooling effectiveness can be obtained by changing the injection angle of the inlet air jet, the location of the inlet grill, or the size of the inlet grill. It was concluded that these study results may be relevant to other applications, such as the design of power transformers, the design of cooling systems for spent nuclear fuel and computer server cooling racks. 13 refs., 12 figs.

Dynamic behavior and identification of failure modes of cooling towers

International Nuclear Information System (INIS)

Serhan, S.J.

1994-01-01

The major thrust of this paper is to provide an engineering assessment of two hyperboloidal 540-foot high reinforced concrete cooling towers at a nuclear power plant relative to the proposed construction of a new safety-related facility in the shadow of these cooling towers. A three-dimensional full 360-degree finite-element model that is capable of realistically representing the response of the two cooling towers subjected to the plant design-basis safe shutdown earthquake, 90 mph wind, and 300 mph tornado is used to create a data pool which supports the proposed construction of the new facility. Dynamic time history analyses are performed to represent the complex interplay of the dynamic characteristics of the cooling towers and the input wind-pressure excitation in terms of gust factors. This study resulted in the confirmation and enhancement of many of the important aspects in the design/analysis methodologies for cooling towers reported in literature. In summary, this study provides a high confidence that no significant damage will be caused to the two cooling towers when subjected to the plant design-basis safe shutdown earthquake and the 90 mph basic wind velocity. However, the two cooling towers are expected to collapse if subjected in a direct hit to a 300 mph tornado. The nonlinear finite element analyses including base uplift performed for this study and the literature research on past failures of cooling towers due to severe wind storms confirm that the mode of failure will not be the overturning cantilever tree-type and the towers will collapse inwardly with the exception of few isolated debris

Cooling tower performance improvements for a cycling PC-fired unit

International Nuclear Information System (INIS)

Keckritz, M.; Thelen, A.

1997-01-01

The inevitable deregulation of the electric utility industry has caused many electric utility companies to look closely at their existing assets and predict what role these units will play in the future. Reducing a unit's production cost is the best way to prepare for the deregulated market but this benefit often comes with an associated capital expenditure. Spending capital dollars today can pose a quandary for an investor-owned utility committed to maintaining low consumer rates. The dilemma is: How does a utility improve its competitiveness position today while ensuring that the shareholders are getting a fair return on their investment when any fuel savings are passed through to the consumer? Illinois Power (IP) has been aggressively looking to improve their current competitive position while facing the current regulatory challenges. Studies have been commissioned to identify the most attractive cost reduction opportunities available. One study identified that improving the performance of the Unit 6 cooling tower at the Havana Station would be a very economically attractive option. This paper addresses the economics of refurbishing a cooling tower for a cycling pulverized-coal (PC) unit to provide a competitive advantage leading into the deregulated electricity market

Experimental investigation of filled bed effect on the thermal performance of a wet cooling tower by using ZnO/water nanofluid

International Nuclear Information System (INIS)

Imani-Mofrad, Peyman; Saeed, Zeinali Heris; Shanbedi, Mehdi

2016-01-01

Highlights: • Effect of filled bed on performance of cooling tower with ZnO nanofluid evaluated. • Applying metal reticular bed is the best choice when ZnO/water nanofluid is used. • Metal reticular bed showed lowest fouling and agglomeration of nanoparticles. • Nanofluid improved cooling range, characteristic & effectiveness of cooling tower. - Abstract: This study deals with an experimental investigation on the effect of different types of filled beds on the thermal performance of a wet cooling tower by using zinc oxide (ZnO)/water nanofluid. Different concentrations of ZnO/water nanofluid were prepared through two-step procedure by using pure water with electrical conductivity of 2 μS/cm. First, by using ZnO/water nanofluid (0.08 wt%), effect of six different filled beds were investigated on the thermal performance of the cooling tower. Moreover, after each experiment the applied filled bed was reviewed in order to observe any aggregation or settlement of nanoparticles on the surfaces of the bed. It was found that applying metal reticular bed (Bed 1) is the best choice when ZnO/water nanofluid is used. In the other word Bed 1 results better thermal characteristics for cooling tower and less settlement of nanofluids. Then different concentrations of ZnO/water nanofluid in the range of 0.02–0.1 wt% is employed in the cooling tower by utilizing Bed 1. The results showed that by using nanofluids, cooling range, tower characteristic (TC) and effectiveness of cooling tower are enriched compared to water. For example, TC enhanced by 21.5% and 22.5% for ZnO/water nanofluid with concentration of 0.02 wt% and 0.05 wt%, respectively.

Effects of geometry on slot-jet film cooling performance

Energy Technology Data Exchange (ETDEWEB)

Hyams, D.G.; McGovern, K.T.; Leylek, J.H. [Clemson Univ., SC (United States)

1995-10-01

The physics of the film cooling process for shaped, inclined slot-jets with realistic slot-length-to-width ratios (L/s) is studied for a range of blowing ratio (M) and density ratio (DR) parameters typical of gas turbine operations. For the first time in the open literature, the effect of inlet and exit shaping of the slot-jet on both flow and thermal field characteristics is isolated, and the dominant mechanisms responsible for differences in these characteristics are documented. A previously documented computational methodology was applied for the study of four distinct configurations: (1) slot with straight edges and sharp corners (reference case); (2) slot with shaped inlet region; (3) slot with shaped exit region; and (4) slot with both shaped inlet and exit regions. Detailed field results as well as surface phenomena involving adiabatic film effectiveness ({eta}) and heat transfer coefficient (h) are presented. It is demonstrated that both {eta} and h results are vital in the proper assessment of film cooling performance. All simulations were carried out using a multi-block, unstructured/adaptive grid, fully explicit, time-marching solver with multi-grid, local time stepping, and residual smoothing type acceleration techniques. Special attention was paid to and full documentation provided for: (1) proper modeling of the physical phenomena; (2) exact geometry and high quality grid generation techniques; (3) discretization schemes; and (4) turbulence modeling issues. The key parameters M and DR were varied from 1.0 to 2.0 and 1.5 to 2.0, respectively, to show their influence. Simulations were repeated for slot length-to-width ratio (L/s) of 3.0 and 4.5 in order to explain the effects of this important parameter. Additionally, the performance of two popular turbulence models, standard k-F, and RNG k-E, were studied to establish their ability to handle highly elliptic jet/crossflow interaction type processes.

Maximization of the Thermoelectric Cooling of a Graded Peltier Device by Analytical Heat-Equation Resolution

Science.gov (United States)

Thiébaut, E.; Goupil, C.; Pesty, F.; D'Angelo, Y.; Guegan, G.; Lecoeur, P.

2017-12-01

Increasing the maximum cooling effect of a Peltier cooler can be achieved through material and device design. The use of inhomogeneous, functionally graded materials may be adopted in order to increase maximum cooling without improvement of the Z T (figure of merit); however, these systems are usually based on the assumption that the local optimization of the Z T is the suitable criterion to increase thermoelectric performance. We solve the heat equation in a graded material and perform both analytical and numerical analysis of a graded Peltier cooler. We find a local criterion that we use to assess the possible improvement of graded materials for thermoelectric cooling. A fair improvement of the cooling effect (up to 36%) is predicted for semiconductor materials, and the best graded system for cooling is described. The influence of the equation of state of the electronic gas of the material is discussed, and the difference in term of entropy production between the graded and the classical system is also described.

The Effect of Variable Gravity on the Cooling Performance of a 16-Nozzle Spray Array

National Research Council Canada - National Science Library

Elston, Levi J; Yerkes, Kirk L; Thomas, Scott K; McQuillen, John

2008-01-01

The objective of this thesis was to investigate the cooling performance of a 16-nozzle spray array, using FC-72 as the working fluid, in variable gravity conditions with additional emphasis on fluid...

Film cooling adiabatic effectiveness measurements of pressure side trailing edge cooling configurations

Directory of Open Access Journals (Sweden)

R. Becchi

2015-12-01

Full Text Available Nowadays total inlet temperature of gas turbine is far above the permissible metal temperature; as a consequence, advanced cooling techniques must be applied to protect from thermal stresses, oxidation and corrosion the components located in the high pressure stages, such as the blade trailing edge. A suitable design of the cooling system for the trailing edge has to cope with geometric constraints and aerodynamic demands; state-of-the-art of cooling concepts often use film cooling on blade pressure side: the air taken from last compressor stages is ejected through discrete holes or slots to provide a cold layer between hot mainstream and the blade surface. With the goal of ensuring a satisfactory lifetime of blades, the design of efficient trailing edge film cooling schemes and, moreover, the possibility to check carefully their behavior, are hence necessary to guarantee an appropriate metal temperature distribution. For this purpose an experimental survey was carried out to investigate the film covering performance of different pressure side trailing edge cooling systems for turbine blades. The experimental test section consists of a scaled-up trailing edge model installed in an open loop suction type test rig. Measurements of adiabatic effectiveness distributions were carried out on three trailing edge cooling system configurations. The baseline geometry is composed by inclined slots separated by elongated pedestals; the second geometry shares the same cutback configuration, with an additional row of circular film cooling holes located upstream; the third model is equipped with three rows of in-line film cooling holes. Experiments have been performed at nearly ambient conditions imposing several blowing ratio values and using carbon dioxide as coolant in order to reproduce a density ratio close to the engine conditions (DR=1.52. To extend the validity of the survey a comparison between adiabatic effectiveness measurements and a prediction by

Corrosion resistance of high performance stainless steels in cooling water and other refinery environments

International Nuclear Information System (INIS)

Kovach, C.W.; Redmerski, L.S.

1984-01-01

The recent successful introduction of high performance stainless steels as tubing for seawater cooled electric utility condensers suggests that these alloys can also provide useful service in refinery heat exchanger applications. Since many of these applications involve higher temperature exposure than steam condensers, a study was conducted to evaluate crevice corrsion resistance over a range of cooling water temperature and chloride concentrations, and also to evaluate general corrosion resistance in some strong chemical and refinery environments. These stainless steels display excellent crevice corrosion resistance as well as good resistance to a variety of chemical environments that may be encountered in refinery, petrochemical and chemical plant service

Comparison of Core Performance with Various Oxide fuels on Sodium Cooled Fast Reactor

Energy Technology Data Exchange (ETDEWEB)

Choi, Jin Ha; Kim, Myung Hyun [Kyung Hee University, Yongin (Korea, Republic of)

2016-05-15

The system is called Prototype GenIV Sodium-cooled Fast Reactor (PGSFR). Ultimate goal of PGSFR is test for capability of TRU transmutation. Purpose of this study is test for evaluation of in-core performance and TRU transmutation performance by applying various oxide fuel loaded TRU. Fuel type of reference core is changed to uranium-based oxide fuel. Oxide fuel has a lot of experience through fuel fabrication and reactor operation. This study performed by compared and analyzed a core performance of various oxide fuels. (U,Pu)O{sub 2} and (U,TRU)O{sub 2} which various oxide fuel types are selected as extreme case for comparison with core performance and transmutation capability of TRU isotopes. Thorium-based fuel is known that it has good performance for burner reactor due to low proliferation characteristic. To check the performance of TRU incineration for comparison with uranium-based fuel on prototype SFR, Thorium-based fuel, (Th,U)O{sub 2}, (Th,Pu)O{sub 2} and (Th,TRU)O{sub 2}, is selected. Calculations of core performance for various oxide fuel are performed using the fast calculation tool, TRANSX / DANTSTS / REBUS-3. In this study, comparison of core performance and transmutation performance is conducted with various fuel types in a sodium-cooled fast reactor. Mixed oxide fuel with TRU can produce the energy with small amount of fissile material. However, the TRU fuel is confirmed to bring a potential decline of the safety parameters. In case of (Th,U)O2 fuel, the flux level in thermal neutron region becomes lower because of higher capture cross-section of Th-232 than U-238. However, Th-232 has difficulty in converting to TRU isotopes. Therefore, the TRU consumption mass is relatively high in mixed oxide fuel with thorium and TRU.

Comparison of Core Performance with Various Oxide fuels on Sodium Cooled Fast Reactor

International Nuclear Information System (INIS)

Choi, Jin Ha; Kim, Myung Hyun

2016-01-01

The system is called Prototype GenIV Sodium-cooled Fast Reactor (PGSFR). Ultimate goal of PGSFR is test for capability of TRU transmutation. Purpose of this study is test for evaluation of in-core performance and TRU transmutation performance by applying various oxide fuel loaded TRU. Fuel type of reference core is changed to uranium-based oxide fuel. Oxide fuel has a lot of experience through fuel fabrication and reactor operation. This study performed by compared and analyzed a core performance of various oxide fuels. (U,Pu)O_2 and (U,TRU)O_2 which various oxide fuel types are selected as extreme case for comparison with core performance and transmutation capability of TRU isotopes. Thorium-based fuel is known that it has good performance for burner reactor due to low proliferation characteristic. To check the performance of TRU incineration for comparison with uranium-based fuel on prototype SFR, Thorium-based fuel, (Th,U)O_2, (Th,Pu)O_2 and (Th,TRU)O_2, is selected. Calculations of core performance for various oxide fuel are performed using the fast calculation tool, TRANSX / DANTSTS / REBUS-3. In this study, comparison of core performance and transmutation performance is conducted with various fuel types in a sodium-cooled fast reactor. Mixed oxide fuel with TRU can produce the energy with small amount of fissile material. However, the TRU fuel is confirmed to bring a potential decline of the safety parameters. In case of (Th,U)O2 fuel, the flux level in thermal neutron region becomes lower because of higher capture cross-section of Th-232 than U-238. However, Th-232 has difficulty in converting to TRU isotopes. Therefore, the TRU consumption mass is relatively high in mixed oxide fuel with thorium and TRU.

Evaluating long-term performance of in situ vitrified waste forms: Methodology and results

International Nuclear Information System (INIS)

McGrail, B.P.; Olson, K.M.

1992-11-01

In situ vitrification (ISV) is an emerging technology for the remediation of hazardous and radioactive waste sites. The concept relies on the principle of Joule heating to raise the temperature of a soil between an array of electrodes above the melting temperature. After cooling, the melt solidifies into a massive glass and crystalline block similar to naturally occurring obsidian. Determining the long-term performance of ISV products in a changing regulatory environment requires a fundamental understanding of the mechanisms controlling the dissolution behavior of the material. A series of experiments was performed to determine the dissolution behavior of samples produced from the ISV processing of typical soils from the Idaho National Engineering Laboratory subsurface disposal area. Dissolution rate constant measurements were completed at 90 degrees C over the pH range 2 to 11 for one sample obtained from a field test of the ISV process

Experimental study on energy performance of a split air-conditioner by using variable thickness evaporative cooling pads coupled to the condenser

International Nuclear Information System (INIS)

Martínez, P.; Ruiz, J.; Cutillas, C.G.; Martínez, P.J.; Kaiser, A.S.; Lucas, M.

2016-01-01

A well known strategy for improving the performance of air conditioning systems when using air-condensed units is to decrease the ambient inlet airflow temperature by means of an evaporative cooling pad. In this work experiments are conducted in a split air-conditioning system where the condensing unit is modified by coupling different evaporative cooling pads with variable thickness. The impact of the different cooling pads on the overall performance of the air-conditioning system is experimentally determined by measuring the airflow conditions and the energy consumption of the overall air conditioning system, including both the condenser fan and the feedwater recirculation pump of the cooling pads. The aim is to determine the energy efficiency improvement achieved by pre-cooling the ambient airflow compared to a common air-condensed unit and to calculate the optimal pad thickness that maximize the overall COP of the system. Experimental results indicate that the best overall COP is obtained by adding a cooling pad thickness of about 100 mm. At that point the compressor power consumption is reduced by 11.4%, the cooling capacity is increased by 1.8% and finally the overall COP is increased by 10.6%.

Cooling load and coefficient of performance optimizations for real air-refrigerators

International Nuclear Information System (INIS)

Tu Youming; Chen Lingen; Sun Fengrui; Wu Chih

2006-01-01

Based on a simple irreversible variable-temperature heat reservoir air (Brayton) refrigeration cycle model, a performance analysis and optimization of a real air refrigerator is carried out using finite-time thermodynamics. To maximize the cooling load and the coefficient of performance (COP) of the cycle, the allocation of a fixed total heat-exchanger inventory and thermal-capacity rate matching between the working fluid and heat reservoirs are optimized, respectively. The influences of pressure ratio, the total heat-exchanger inventory, the efficiencies of the compressor and expander, the thermal capacity rate of the working fluid and the ratio of the thermal-capacity rates of the heat reservoirs on the performance of the cycle are shown by numerical examples. The results obtained provide guidances for the design of practical air-refrigeration plants

Physiological and productive responses of multiparous lactating Holstein cows exposed to short-term cooling during severe summer conditions in an arid region of Mexico

Science.gov (United States)

Avendaño-Reyes, L.; Hernández-Rivera, J. A.; Álvarez-Valenzuela, F. D.; Macías-Cruz, U.; Díaz-Molina, R.; Correa-Calderón, A.; Robinson, P. H.; Fadel, J. G.

2012-11-01

Heat stress generates a significant economic impact for the dairy industry in arid and semi-arid regions of the world, so that heat abatement is an important issue for dairy producers. The objective of this study was to evaluate effects of two short-term cooling periods on physiological and productive status of lactating Holstein cows during hot ambient temperatures. Thirty-nine multiparous cows were blocked by milk yield and assigned to one of three treatments including: control group (C), cows cooled before milking time (0500 and 1700 h daily, 1 h cooling); AM group, cows cooled at 1000 h and before milking (2 h cooling); and AM + PM group, cows cooled at 1100, 1500 and 2200 h, as well as before milking (4 h cooling). The cooling system was placed in the holding pen which the cows were moved through for cooling. Respiratory rate, and temperatures of thurl and right flank, were lower ( P cows from the AM + PM group than AM and C cows during the morning and afternoon. However, udder temperature was higher in the AM + PM group compared to AM and C groups during the afternoon, although lower than the AM group during the morning. Rectal temperature was similar in all groups. Thyroxin concentrations tended ( P cows had a trend ( P cows.

Ventilative Cooling

DEFF Research Database (Denmark)

Heiselberg, Per Kvols; Kolokotroni, Maria

This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state......-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...

Long-term bridge performance high priority bridge performance issues.

Science.gov (United States)

2014-10-01

Bridge performance is a multifaceted issue involving performance of materials and protective systems, : performance of individual components of the bridge, and performance of the structural system as a whole. The : Long-Term Bridge Performance (LTBP)...

Radiative cooling test facility and performance evaluation of 4-MIL aluminized polyvinyl fluoride and white-paint surfaces

Energy Technology Data Exchange (ETDEWEB)

Kruskopf, M.S.; Berdahl, P.; Martin, M.; Sakkal, F.; Sobolewski, M.

1980-11-01

A test facility designed to measure the amount of radiative cooling a specific material or assembly of materials will produce when exposed to the sky is described. Emphasis is placed upon assemblies which are specifically designed to produce radiative cooling and which therefore offer promise for the reduction of temperatures and/or humidities in occupied spaces. The hardware and software used to operate the facility are documented and the results of the first comprehensive experiments are presented. A microcomputer-based control/data acquisition system was employed to study the performance of two prototype radiator surfaces: 4-mil aluminized polyvinyl fluoride (PVF) and white painted surfaces set below polyethylene windscreens. The cooling rates for materials tested were determined and can be approximated by an equation (given). A computer model developed to simulate the cooling process is presented. (MCW)

Performance evaluation of combined ejector LiBr/H2O absorption cooling cycle

Directory of Open Access Journals (Sweden)

Hasan Sh. Majdi

2016-03-01

Full Text Available The objective of this work is to develop a computer simulation program to evaluate the performance of solar-assited combined ejector absorption (single-effect cooling system using LiBr/H2O as a working fluid and operating under steady-state conditions. The ejector possess no moving parts and is simple and reliable, which makes it attractive for combination with single-stage absorption cycle for further improvement to the system's performance. In this research, improvement to the system is achieved by utilizing the potential kinetic energy of the ejector to enhance refrigeration efficiency. The effects of the entrainment ratio of the ejector, operating temperature, on the thermal loads, and system performance have been investigated. The results showed that the evaporator and condenser loads, post-addition of the ejector, is found to be permanently higher than that in the basic cycle, which indicates a significant enhancement of the proposed cycle and the cooling capacity of the system increasing with the increase in evaporator temperature and entrainment ratio. The COP of the modified cycle is improved by up to 60 % compared with that of the basic cycle at the given condition. This process stabilizes the refrigeration system, enhanced its function, and enabled the system to work under higher condenser temperatures.

Effect of air condition on AP-1000 containment cooling performance in station black out accident

International Nuclear Information System (INIS)

Hendro Tjahjono

2015-01-01

AP1000 reactor is a nuclear power plant generation III+ 1000 MWe which apply passive cooling concept to anticipate accidents triggered by the extinction of the entire supply of electrical power or Station Black Out (SBO). In the AP1000 reactor, decay heat disposal mechanism conducted passively through the PRHR-IRWST and subsequently forwarded to the reactor containment. Containment externally cooled through natural convection in the air gap and through evaporation cooling water poured on the outer surface of the containment wall. The mechanism of evaporation of water into the air outside is strongly influenced by the conditions of humidity and air temperature. The purpose of this study was to determine the extent of the influence of the air condition on cooling capabilities of the AP1000 containment. The method used is to perform simulations using Matlab-based analytical calculation model capable of estimating the power of heat transferred. The simulation results showed a decrease in power up to 5% for relative humidity rose from 10% to 95%, while the variation of air temperature of 10°C to 40°C, the power will decrease up to 15%. It can be concluded that the effect of air temperature increase is much more significant in lowering the containment cooling ability compared with the increase of humidity. (author)

Use of a temperature-initiated passive cooling system (TIPACS) for the modular high-temperature gas-cooled reactor cavity cooling system (RCCS)

International Nuclear Information System (INIS)

Forsberg, C.W.; Conklin, J.; Reich, W.J.

1994-04-01

A new type of passive cooling system has been invented (Forsberg 1993): the Temperature-Initiated Passive Cooling System (TIPACS). The characteristics of the TIPACS potentially match requirements for an improved reactor-cavity-cooling system (RCCS) for the modular high-temperature gas-cooled reactor (MHTGR). This report is an initial evaluation of the TIPACS for the MHTGR with a Rankines (steam) power conversion cycle. Limited evaluations were made of applying the TIPACS to MHTGRs with reactor pressure vessel temperatures up to 450 C. These temperatures may occur in designs of Brayton cycle (gas turbine) and process heat MHTGRs. The report is structured as follows. Section 2 describes the containment cooling issues associated with the MHTGR and the requirements for such a cooling system. Section 3 describes TIPACS in nonmathematical terms. Section 4 describes TIPACS's heat-removal capabilities. Section 5 analyzes the operation of the temperature-control mechanism that determines under what conditions the TIPACS rejects heat to the environment. Section 6 addresses other design and operational issues. Section 7 identifies uncertainties, and Section 8 provides conclusions. The appendixes provide the detailed data and models used in the analysis

Use of a temperature-initiated passive cooling system (TIPACS) for the modular high-temperature gas-cooled reactor cavity cooling system (RCCS)

Energy Technology Data Exchange (ETDEWEB)

Forsberg, C.W.; Conklin, J.; Reich, W.J.

1994-04-01

A new type of passive cooling system has been invented (Forsberg 1993): the Temperature-Initiated Passive Cooling System (TIPACS). The characteristics of the TIPACS potentially match requirements for an improved reactor-cavity-cooling system (RCCS) for the modular high-temperature gas-cooled reactor (MHTGR). This report is an initial evaluation of the TIPACS for the MHTGR with a Rankines (steam) power conversion cycle. Limited evaluations were made of applying the TIPACS to MHTGRs with reactor pressure vessel temperatures up to 450 C. These temperatures may occur in designs of Brayton cycle (gas turbine) and process heat MHTGRs. The report is structured as follows. Section 2 describes the containment cooling issues associated with the MHTGR and the requirements for such a cooling system. Section 3 describes TIPACS in nonmathematical terms. Section 4 describes TIPACS`s heat-removal capabilities. Section 5 analyzes the operation of the temperature-control mechanism that determines under what conditions the TIPACS rejects heat to the environment. Section 6 addresses other design and operational issues. Section 7 identifies uncertainties, and Section 8 provides conclusions. The appendixes provide the detailed data and models used in the analysis.

Cooling for newborns with hypoxic ischaemic encephalopathy.

Science.gov (United States)

Jacobs, Susan E; Berg, Marie; Hunt, Rod; Tarnow-Mordi, William O; Inder, Terrie E; Davis, Peter G

2013-01-31

Newborn animal studies and pilot studies in humans suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae without adverse effects. To determine the effect of therapeutic hypothermia in encephalopathic asphyxiated newborn infants on mortality, long-term neurodevelopmental disability and clinically important side effects. We used the standard search strategy of the Cochrane Neonatal Review Group as outlined in The Cochrane Library (Issue 2, 2007). Randomised controlled trials evaluating therapeutic hypothermia in term and late preterm newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2007, Issue 2), MEDLINE (1966 to June 2007), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal handsearching. We updated this search in May 2012. We included randomised controlled trials comparing the use of therapeutic hypothermia with standard care in encephalopathic term or late preterm infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome. Four review authors independently selected, assessed the quality of and extracted data from the included studies. Study authors were contacted for further information. Meta-analyses were performed using risk ratios (RR) and risk differences (RD) for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals (CI). We included 11 randomised controlled trials in this updated review, comprising 1505 term and late preterm infants with moderate/severe encephalopathy and evidence of intrapartum asphyxia

Comparative study on thermal performance of natural draft cooling towers with finned shells

International Nuclear Information System (INIS)

Goodarzi, Mohsen

2016-01-01

The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

Comparative study on thermal performance of natural draft cooling towers with finned shells

Energy Technology Data Exchange (ETDEWEB)

Goodarzi, Mohsen [Bu-Ali Sina Univ., Hamedan (Iran, Islamic Republic of). Dept. of Mechanical Engineering

2016-10-15

The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

Passive cooling in modern nuclear reactors

International Nuclear Information System (INIS)

Rouai, N. M.

1998-01-01

This paper presents some recent experimental results performed with the aim of understanding the mechanism of passive cooling. The AP 600 passive containment cooling system is simulated by an electrically heated vertical pipe, which is cooled by a naturally induced air flow and by a water film descending under gravity. The results demonstrate that although the presence of the water film improved the heat transfer significantly, the mode of heat transfer was very dependent on the experimental parameters. Preheating the water improved both film stability and overall cooling performance

Biofouling control of industrial seawater cooling towers

KAUST Repository

Al-Bloushi, Mohammed

2017-01-01

In this study, the research focuses on biofouling control in seawater cooling towers by investigating two different approaches. The first strategy addresses the use of alternative oxidants (i.e. ozone micro-bubbles and chlorine dioxide) in treatment of cooling towers. The second strategy investigates removing nutrients in seawater using granular activated carbon filter column and ultrafiltration to prevent the growth of microorganisms. Laboratory bench-scale tests in terms of temperature, cycle of concentration, dosage, etc. indicated that, at lower oxidant dosages (total residual oxidant (TRO) equivalent = 0.1 mg/l Cl2), chlorine dioxide had a better disinfection effect than chlorine and ozone. The performance of oxidizing biocides at pilot scale, operating at assorted conditions, showed that for the disinfectants tested, ozone could remove 95 % bioactivity of total number of bacteria and algae followed by chlorine dioxide at 85%, while conventional chlorine dosing only gave 60% reduction in bioactivities. Test results of GAC bio-filter showed that around 70 % removal of total organic carbon in the seawater feed was achieved and was effective in keeping the microbial growth to a minimum. The measured results from this study enable designers of seawater cooling towers to manage the biofouling problems when such cooling towers are extrapolated to a pilot scale.

Vapor-cooled lead and stacks thermal performance and design analysis by finite difference techniques

International Nuclear Information System (INIS)

Peck, S.D.; Christensen, E.H.; O'Loughlin, J.M.

1985-01-01

Investigation of the combined thermal performance of the stacks and vapor cooled leads for the Mirror Fusion Test Facility-''B'' demonstrates considerable interdependency. For instance, the heat transfer to the vapor-cooled lead (VCL) from warm bus heaters, environmental enclosure, and stack is a significant additional heat load to the joule heating in the leads, proportionately higher for the lower current leads that have fewer current-carrying, counter flow coolant copper tubes. Consequently, the specific coolant flow (G/sec-kA-lead pair) increases as the lead current decreases. The definition of this interdependency and the definition of necessary thermal management has required an integrated thermal model for the entire stack/VCL assemblies

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.

Topological charge using cooling and the gradient flow

International Nuclear Information System (INIS)

Alexandrou, C.; Athenodorou, A.; The Cyprus Institute, Nicosia; Jansen, K.

2015-12-01

The equivalence of cooling to the gradient flow when the cooling step n c and the continuous flow step of gradient flow τ are matched is generalized to gauge actions that include rectangular terms. By expanding the link variables up to subleading terms in perturbation theory, we relate n c and τ and show that the results for the topological charge become equivalent when rescaling τ ≅ n c /(3-15c 1 ) where c 1 is the Symanzik coefficient multiplying the rectangular term. We, subsequently, apply cooling and the gradient flow using the Wilson, the Symanzik tree-level improved and the Iwasaki gauge actions to configurations produced with N f = 2 + 1 + 1 twisted mass fermions. We compute the topological charge, its distribution and the correlators between cooling and gradient flow at three values of the lattice spacing demonstrating that the perturbative rescaling τ ≅ n c /(3-15c 1 ) leads to equivalent results.

Post-accident cooling capacity analysis of the AP1000 passive spent fuel pool cooling system

International Nuclear Information System (INIS)

Su Xia

2013-01-01

The passive design is used in AP1000 spent fuel pool cooling system. The decay heat of the spent fuel is removed by heating-boiling method, and makeup water is provided passively and continuously to ensure the safety of the spent fuel. Based on the analysis of the post-accident cooling capacity of the spent fuel cooling system, it is found that post-accident first 72-hour cooling under normal refueling condition and emergency full-core offload condition can be maintained by passive makeup from safety water source; 56 hours have to be waited under full core refueling condition to ensure the safety of the core and the spent fuel pool. Long-term cooling could be conducted through reserved safety interface. Makeup measure is available after accident and limited operation is needed. Makeup under control could maintain the spent fuel at sub-critical condition. Compared with traditional spent fuel pool cooling system design, the AP1000 design respond more effectively to LOCA accidents. (authors)

The Role of Absorption Cooling for Reaching Sustainable Energy Systems

Energy Technology Data Exchange (ETDEWEB)

Lindmark, Susanne

2005-07-01

This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO{sub 2} emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield. The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO{sub 2} emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO{sub 2} emissions can be lowered to 45 CO{sub 2}/MWh{sub c} by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study. Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand.

Toward Cooling Uniformity: Investigation of Spiral, Sweeping Holes, and Unconventional Cooling Paradigms

Science.gov (United States)

Shyam, Vikram; Thurman, Douglas R.; Poinsatte, Philip E.; Ameri, Ali A.; Culley, Dennis E.

2018-01-01

Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. Ways to quantify the efficacy of novel cooling holes that are asymmetric, not uniformly spaced or that show variation from hole to hole are presented. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and square holes. A patent-pending spiral hole design showed the highest potential of the nondiffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing ratios of 1.0, 1.5, 2.0, and 2.5 at a density ratio of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS. A section on ideas for future work is included that addresses issues of quantifying cooling uniformity and provides some ideas for changing the way we think about cooling such as changing the direction of cooling or coupling acoustic devices to cooling holes to regulate frequency.

Man-portable personal cooling garment based on vacuum desiccant cooling

International Nuclear Information System (INIS)

Yang Yifan; Stapleton, Jill; Diagne, Barbara Thiané; Kenny, Glen P.; Lan, Christopher Q.

2012-01-01

A man-portable personal cooling garment based on the concept of vacuum desiccant cooling (VDC) was developed. It was demonstrated with cooling pads that a cooling capacity of 373.1 W/m 2 could be achieved in an ambient environment of 37 °C. Tests with human subjects wearing prototype cooling garments consisting of 12 VDC pads with an overall weight of 3.4 kg covering 0.4 m 2 body surface indicate that the garment could maintain a core temperature substantially lower than the control when the workload was walking on a treadmill of 2% inclination at 3 mph. The exercise was carried out in an environment of 40 °C and 50% relative humidity (RH) for 60 min. Tests also showed that the VDC garment could effectively reduce the metabolic heat accumulation in body with subject wearing heavily insulated nuclear, biological and chemical (NBC) suit working in the heat and allow the participant to work safely for 60 min, almost doubling the safe working time of the same participant when he wore NBC suit only. - Highlights: ► Heat stress mitigation is important for workers health, safety, and performance. ► Vacuum desiccant cooling (VDC) a novel concept for personal cooling. ► VDC garment man-portable and more efficient than commercial ice/pad vest. ► VDC garment suitable for personal cooling with NBC suit.

Optimization of advanced gas-cooled reactor fuel performance by a stochastic method

International Nuclear Information System (INIS)

Parks, G.T.

1987-01-01

A brief description is presented of a model representing the in-core behaviour of a single advanced gas-cooled reactor fuel channel, developed specifically for optimization studies. The performances of the only suitable Numerical Algorithms Group (NAG) library package and a Metropolis algorithm routine on this problem are discussed and contrasted. It is concluded that, for the problem in question, the stochastic Metropolis algorithm has distinct advantages over the deterministic NAG routine. (author)

Failure Mode and Effects Analysis (FMEA) of the Emergency Core Cooling System (ECCS) for a Westinghouse type 312, three loop pressurized water reactor

International Nuclear Information System (INIS)

Shopsky, W.E.

1977-01-01

The Emergency Core Cooling System (ECCS) is a Safeguards System designed to cool the core in the unlikely event of a Loss-of-Coolant Accident (LOCA) in the primary reactor coolant system as well as to provide additional shutdown capability following a steam break accident. The system is designed for a high reliability of providing emergency coolant and shutdown reactivity to the core for all anticipated occurrences of such accidents. The ECCS by performing its intended function assures that fuel and clad damage is minimized during accident conditions thus reducing release of fission products from the fuel. The ECCS is designed to perform its function despite sustaining a single failure by the judicious use of equipment and flow path redundancy within and outside the containment structure. By the use of an analytic tool, a Failure Mode and Effects Analysis (FMEA), it is shown that the ECCS is in compliance with the Single Failure Criterion established for active failures of fluid systems during short and long term cooling of the reactor core following a LOCA or steam break accident. An analysis was also performed with regards to passive failure of ECCS components during long-term cooling of the core following an accident. The design of the ECCS was verified as being able to tolerate a single passive failure during long-term cooling of the reactor core following an accident. The FMEA conducted qualitatively demonstrates the reliability of the ECCS (concerning active components) to perform its intended safety function

Mathematical Modeling – The Impact of Cooling Water Temperature Upsurge on Combined Cycle Power Plant Performance and Operation

Science.gov (United States)

Indra Siswantara, Ahmad; Pujowidodo, Hariyotejo; Darius, Asyari; Ramdlan Gunadi, Gun Gun

2018-03-01

This paper presents the mathematical modeling analysis on cooling system in a combined cycle power plant. The objective of this study is to get the impact of cooling water upsurge on plant performance and operation, using Engineering Equation Solver (EES™) tools. Power plant installed with total power capacity of block#1 is 505.95 MWe and block#2 is 720.8 MWe, where sea water consumed as cooling media at two unit condensers. Basic principle of analysis is heat balance calculation from steam turbine and condenser, concern to vacuum condition and heat rate values. Based on the result shown graphically, there were impact the upsurge of cooling water to increase plant heat rate and vacuum pressure in condenser so ensued decreasing plant efficiency and causing possibility steam turbine trip as back pressure raised from condenser.

Thermal-Hydraulic Performance of a Corrugated Cooling Fin with Louvered Surfaces

DEFF Research Database (Denmark)

Sønderby, Simon Kaltoft; Hosseini, Seyed Mojtaba Mir; Rezaniakolaei, Alireza

2017-01-01

The main objective of the article is to investigate thermal-hydraulic performance of a corrugated cooling fin with louvered surfaces. The investigation is carried out using the fin geometry of one most commonly used liquid-to-air heat exchangers. The investigation was carried out by numerically...... simulating the airflow with louvered fin geometry. The simulation model was verified by comparing simulated j- and f-factors with the corresponding values of several experimental correlations. The j-factors deviated less than 10.7 % from two of the experimental correlations, whereas deviations ranging...

Comparative performance analysis of ice plant test rig with TiO2-R-134a nano refrigerant and evaporative cooled condenser

OpenAIRE

Amrat Kumar Dhamneya; S.P.S. Rajput; Alok Singh

2018-01-01

The nanoparticle is used in chillers for increasing system performance. The increasing concentration of nanoparticles (TiO2) in refrigerant increases the performances of the system due decreasing compressor work done and enhance heat transfer rate. For hot and dry climate condition, performances of air-cooled condenser minimize, and C. O. P. decreases extensively in chillers due to heat transfer rate decreases in the condenser. In the condenser, nano-refrigerants are not cool at the desired l...

Solar heating and cooling system with absorption chiller and low temperature latent heat storage: Energetic performance and operational experience

Energy Technology Data Exchange (ETDEWEB)

Helm, M.; Keil, C.; Hiebler, S.; Mehling, H.; Schweigler, C. [Bavarian Center for Applied Energy Research (ZAE Bayern) (Germany)

2009-06-15

Absorption cooling systems based on water/lithium bromide (LiBr) solution typically require an open wet cooling tower to transfer the reject heat to the ambient. Yet, water consumption, the need for water make-up and cleaning, formation of fog, and the risk of Legionella bacteria growth are hindering factors for the implementation of small solar cooling systems. The application of a latent heat storage supporting the heat rejection of the absorption chiller in conjunction with a dry cooling system allows eliminating the wet cooling tower. By that means heat rejection of the chiller is shifted to periods with lower ambient temperatures, i.e. night time or off-peak hours. The system concept and the hydraulic scheme together with an analysis of the energetic performance of the system are presented, followed by a report on the operation of a first pilot installation. (author)

Graphite-modified cooling ceiling. A comparative evaluation of the performance; Graphitmodifizierte Kuehldecken. Eine vergleichende Bewertung zur Leistungsfaehigkeit

Energy Technology Data Exchange (ETDEWEB)

Hauser, Gerd [Technische Univ. Muenchen (Germany); Fraunhofer-Institut fuer Bauphysik, Stuttgart (Germany); Hausladen, Gerhard [Technische Univ. Muenchen (Germany); Ingenieurbuero Hausladen GmbH, Muenchen (Germany); Jacobsen, Cornelia; Hutter, Christina; Hanusch, Christoph [Ingenieurbuero Hausladen GmbH, Muenchen (Germany); Schlitzberger, Stephan [Ingenieurbuero fuer Bauphysik Prof. Dr. Hauser GmbH, Kassel (Germany)

2013-03-01

In most cases, the utilization of graphite-modified building materials enhances their thermal conductivity. Thus, chilled ceiling systems achieve an enhanced thermal absorption in comparison to commercial chilled ceiling systems. For this, a simulation for the estimation of the thermal comfort as well as for the quantification of the impacts on the demand of electricity for the refrigeration is performed. The enhanced cooling capacity of the graphite-modified cooling ceiling 'Ecophit' affects the operation positively.

Long-term associative learning predicts verbal short-term memory performance

OpenAIRE

Jones, Gary; Macken, Bill

2017-01-01

Studies using tests such as digit span and nonword repetition have implicated short-term memory across a range of developmental domains. Such tests ostensibly assess specialized processes for the short-term manipulation and maintenance of information that are often argued to enable long-term learning. However, there is considerable evidence for an influence of long-term linguistic learning on performance in short-term memory tasks that brings into question the role of a specialized short-term...

Cool Sportswear

Science.gov (United States)

1982-01-01

New athletic wear design based on the circulating liquid cooling system used in the astronaut's space suits, allows athletes to perform more strenuous activity without becoming overheated. Techni-Clothes gear incorporates packets containing a heat-absorbing gel that slips into an insulated pocket of the athletic garment and is positioned near parts of the body where heat transfer is most efficient. A gel packet is good for about one hour. Easily replaced from a supply of spares in an insulated container worn on the belt. The products, targeted primarily for runners and joggers and any other athlete whose performance may be affected by hot weather, include cooling headbands, wrist bands and running shorts with gel-pack pockets.

Biofouling control of industrial seawater cooling towers

KAUST Repository

Albloushi, Mohammed

2017-11-01

The use of seawater in cooling towers for industrial applications has much merit in the Gulf Cooperation Council countries due to the scarcity and availability of fresh water. Seawater make-up in cooling towers is deemed the most feasible because of its unlimited supply in coastal areas. Such latent-heat removal with seawater in cooling towers is several folds more efficient than sensible heat extraction via heat exchangers. Operational challenges such as scaling, corrosion, and biofouling are a major challenge in conventional cooling towers, where the latter is also a major issue in seawater cooling towers. Biofouling can significantly hamper the efficiency of cooling towers. The most popular methods used in cooling treatment to control biofouling are disinfection by chlorination. However, the disadvantages of chlorination are formation of harmful disinfection byproducts in the presence of high organic loading and safety concerns in the storage of chlorine gas. In this study, the research focuses on biofouling control in seawater cooling towers by investigating two different approaches. The first strategy addresses the use of alternative oxidants (i.e. ozone micro-bubbles and chlorine dioxide) in treatment of cooling towers. The second strategy investigates removing nutrients in seawater using granular activated carbon filter column and ultrafiltration to prevent the growth of microorganisms. Laboratory bench-scale tests in terms of temperature, cycle of concentration, dosage, etc. indicated that, at lower oxidant dosages (total residual oxidant (TRO) equivalent = 0.1 mg/l Cl2), chlorine dioxide had a better disinfection effect than chlorine and ozone. The performance of oxidizing biocides at pilot scale, operating at assorted conditions, showed that for the disinfectants tested, ozone could remove 95 % bioactivity of total number of bacteria and algae followed by chlorine dioxide at 85%, while conventional chlorine dosing only gave 60% reduction in bioactivities

Solar-Cooled Hotel in the Virgin Islands

Science.gov (United States)

Harber, H.

1982-01-01

Performance of solar cooling system is described in 21-page report. System provides cooling for public areas including ball rooms, restaurant, lounge, lobby and shops. Chilled water from solar-cooling system is also used to cool hot water from hotel's desalinization plant.

Active and passive cooling methods for dwellings

DEFF Research Database (Denmark)

Oropeza-Perez, Ivan; Østergaard, Poul Alberg

2018-01-01

In this document a review of three active as well as ten passive cooling methods suitable for residential buildings is carried out. The review firstly addresses how the various technologies cool the space according to the terms of the building heat balance, under what technical conditions...... ventilation, controlled ventilation, roof coating and eco-evaporative cooling are the most suitable passive methods for an extensive use in this country....

Energy saving potential of an indirect evaporative cooler as a pre-cooling unit for mechanical cooling systems in Iran

Energy Technology Data Exchange (ETDEWEB)

Delfani, Shahram; Esmaeelian, Jafar; Karami, Maryam [Department of Installation, Building and Housing Research Center (BHRC), PO Box 13145-1696, Tehran (Iran, Islamic Republic of); Pasdarshahri, Hadi [Department of Mechanical Engineering, Tarbiat Modares University, PO Box 14115-143, Tehran (Iran, Islamic Republic of)

2010-11-15

The performance of indirect evaporative cooling system (IEC) to pre-cool air for a conventional mechanical cooling system has been investigated for four cities of Iran. For this purpose, a combined experimental setup consisting of an IEC unit followed by a packaged unit air conditioner (PUA) was designed, constructed and tested. Two air simulators were designed and used to simulate indoor heating load and outdoor design conditions. Using of experimental data and an appropriate analytical method, the performance and energy reduction capability of combined system has been evaluated through the cooling season. The results indicate IEC can reduce cooling load up to 75% during cooling seasons. Also, 55% reduction in electrical energy consumption of PUA can be obtained. (author)

Heat transfer performance comparison of steam and air in gas turbine cooling channels with different rib angles

Science.gov (United States)

Shi, Xiaojun; Gao, Jianmin; Xu, Liang; Li, Fajin

2013-11-01

Using steam as working fluid to replace compressed air is a promising cooling technology for internal cooling passages of blades and vanes. The local heat transfer characteristics and the thermal performance of steam flow in wide aspect ratio channels ( W/ H = 2) with different angled ribs on two opposite walls have been experimentally investigated in this paper. The averaged Nusselt number ratios and the friction factor ratios of steam and air in four ribbed channels were also measured under the same test conditions for comparison. The Reynolds number range is 6,000-70,000. The rib angles are 90°, 60°, 45°, and 30°, respectively. The rib height to hydraulic diameter ratio is 0.047. The pitch-to-rib height ratio is 10. The results show that the Nusselt number ratios of steam are 1.19-1.32 times greater than those of air over the range of Reynolds numbers studied. For wide aspect ratio channels using steam as the coolant, the 60° angled ribs has the best heat transfer performance and is recommended for cooling design.

NKS-R ExCoolSe mid-term report KTH severe accidents research relevant to the NKS-ExCoolSe project[KTH = Royal Institute of Technology, Sweden

Energy Technology Data Exchange (ETDEWEB)

Hyun Sun Park; Truc-Nam Dinh [Royal Inst. of Technology (Sweden)

2006-04-15

The present mid-term progress report is prepared on the recent results from the KTH severe accident research program relevant to the objective of the ExCoolSe project sponsored by the NKS-R program. The previous PRE-MELT-DEL project at KTH sponsored by NKS provided an extensive assessment on the remaining issues of severe accidents in general and suggested the key issues to be resolved such as coolability and steam explosion energetics in ex-vessel which became a backbone of the ExCoolSe project in NKS. The EXCOOLSE project has been integrated with, and leveraged on, parallel research program at KTH on severe accident phenomena the MSWI project which is funded by the APRI program, SKI in Sweden and HSK in Switzerland and produced more understanding of the key remaining issues. During last year, the critical assessment of the existing knowledge and current SAMG and designs of Nordic BWRs identified the research focus and initiated the new series of research activities toward the resolution of the key remaining issues specifically pertaining to the Nordic BWRs.(au)

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.

Development and Test of the Cooling System for the ATLAS Hadron Tile Calorimeter

CERN Document Server

Schlager, Gerolf

2002-01-01

The ATLAS detector is a general-purpose experiment for proton-proton collisions designed to investigate the full range of physical processes at the Large Hadron Collider (LHC). The ATLAS Tile Hadron Calorimeter is designed to measure the energies of jets with a resolution of E/E = 50%/pE 3%, for j j<3. This thesis presents the detailed studies which were carried out with prototypes of the Tilecal cooling system during my year as technical student at CERN. The results will be used to validate and to determine the nal design of the cooling system of the ATLAS Tile calorimeter. The performance of the cooling unit built for the calibration of Tilecal modules was evaluated for various parameters like temperature stability and safety conditions during operation. Additionally I contributed to the analysis of the calorimeter response for di erent cooling temperatures. These results determined the constraints on the operation conditions of the cooling system in terms of temperature stability that will be needed d...

Performance Analysis of an Updraft Tower System for Dry Cooling in Large-Scale Power Plants

Directory of Open Access Journals (Sweden)

Haotian Liu

2017-11-01

Full Text Available An updraft tower cooling system is assessed for elimination of water use associated with power plant heat rejection. Heat rejected from the power plant condenser is used to warm the air at the base of an updraft tower; buoyancy-driven air flows through a recuperative turbine inside the tower. The secondary loop, which couples the power plant condenser to a heat exchanger at the tower base, can be configured either as a constant-pressure pump cycle or a vapor compression cycle. The novel use of a compressor can elevate the air temperature in the tower base to increases the turbine power recovery and decrease the power plant condensing temperature. The system feasibility is evaluated by comparing the net power needed to operate the system versus alternative dry cooling schemes. A thermodynamic model coupling all system components is developed for parametric studies and system performance evaluation. The model predicts that constant-pressure pump cycle consumes less power than using a compressor; the extra compression power required for temperature lift is much larger than the gain in turbine power output. The updraft tower system with a pumped secondary loop can allow dry cooling with less power plant efficiency penalty compared to air-cooled condensers.

Forced flow cooling of ISABELLE dipole magnets

International Nuclear Information System (INIS)

Bamberger, J.A.; Aggus, J.; Brown, D.P.; Kassner, D.A.; Sondericker, J.H.; Strobridge, T.R.

1976-01-01

The superconducting magnets for ISABELLE will use a forced flow supercritical helium cooling system. In order to evaluate this cooling scheme, two individual dipole magnets were first tested in conventional dewars using pool boiling helium. These magnets were then modified for forced flow cooling and retested with the identical magnet coils. The first evaluation test used a l m-long ISA model dipole magnet whose pool boiling performance had been established. The same magnet was then retested with forced flow cooling, energizing it at various operating temperatures until quench occurred. The magnet performance with forced flow cooling was consistent with data from the previous pool boiling tests. The next step in the program was a full-scale ISABELLE dipole ring magnet, 4.25 m long, whose performance was first evaluated with pool boiling. For the forced flow test the magnet was shrunk-fit into an unsplit laminated core encased in a stainless steel cylinder. The high pressure gas is cooled below 4 K by a helium bath which is pumped below atmospheric pressure with an ejector nozzle. The performance of the full-scale dipole magnet in the new configuration with forced flow cooling, showed a 10 percent increase in the attainable maximum current as compared to the pool boiling data

Cool WISPs for stellar cooling excesses

Energy Technology Data Exchange (ETDEWEB)

Giannotti, Maurizio [Physical Sciences, Barry University, 11300 NE 2nd Avenue, Miami Shores, FL 33161 (United States); Irastorza, Igor; Redondo, Javier [Departamento de Física Teórica, Universidad de Zaragoza, Pedro Cerbuna 12, E-50009, Zaragoza, España (Spain); Ringwald, Andreas, E-mail: mgiannotti@barry.edu, E-mail: igor.irastorza@cern.ch, E-mail: jredondo@unizar.es, E-mail: andreas.ringwald@desy.de [Theory group, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, D-22607 Hamburg (Germany)

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.

Cool WISPs for stellar cooling excesses

International Nuclear Information System (INIS)

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

2016-01-01

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.

Environmental sustainability by adoption of alternate cooling media for condenser cooling

International Nuclear Information System (INIS)

Gandhi, Jaymin; Patel, Nilesh

2015-01-01

Water having ability to dissolve most substances and to support biological life, every cooling water system in power plant is subjected to potential operational problems which are mainly corrosion, scaling and biological fouling. Control of cooling water chemistry is very critical in preventing above said problems. In view of scarcity of water and looking into the future trends in the environment protection, water media can be replaced with air. Having such concept in thermal and combined cycle power plants, use of Air-cooled condenser (ACC) for Nuclear power plant may be explored. During last decade number of installations with ACC also increased, largely in response to the growing attention being paid to environmental concerns as well of water scarcity. The rising importance of 'Save Water and Environment', calls for a broader understanding of the design and application principles involved for ACC. This paper identifies the basic configurations of air cooled condensers used in the power industry together with their merits and demerits when compared to those exhibited by traditional steam surface condensers including environmental and corrosion issues. Several factors that affect the performance of air-cooled condensers are described in detail, especially the consequences that result from the fouling of the finned-tubes. To rectify the degradations in performance that result from external tube fouling, a number of cleaning procedures are described. Due to relatively high cost of sweet water and large requirement of sea water, Air cooled condenser may become viable option in future. (author)

Analysis of Two Phase Natural Circulation Flow in the Cooling Channel of the PECS

Energy Technology Data Exchange (ETDEWEB)

Park, R. J; Ha, K. S; Rhee, B. W; Kim, H. Y [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

Decay heat and sensible heat of the relocated and spread corium are removed by the natural circulation flow at the bottom and side wall of the core catcher and the top water cooling of the corium. The coolant in the inclined channel absorbs the decay heat and sensible heat transferred from the corium through the structure of the core catcher body and flows up to the pool as a two phase mixture. On the other hand, some of the pool water will flow into the inlet of the downcomer piping, and will flow into the inclined cooling channel of the core catcher by gravity. As shown in Fig. 1, the engineered cooling channel is designed to provide effective long-term cooling and stabilization of the corium mixture in the core catcher body while facilitating steam venting in the PECS. To maintain the integrity of the ex-vessel core catcher, however, it is necessary that the coolant be sufficiently circulated along the inclined cooling channel to avoid CHF (Critical Heat Flux) on the heating surface of the cooling channel. For this reason, a verification experiment on the cooling capability of the EU-APR1400 core catcher has been performed in the CE (Cooling Experiment)-PECS facility at KAERI. Preliminary simulations of two-phase natural circulation in the CE-PECS were performed to predict two-phase flow characteristics and to determine the natural circulation mass flow rate in the flow channel. In this study, simulations of two-phase natural circulation in a real core catcher of the PECS have been performed to determine the natural circulation mass flow rate in the flow channel using the RELAP5/MOD3 computer code.

Actively controlling coolant-cooled cold plate configuration

Science.gov (United States)

Chainer, Timothy J.; Parida, Pritish R.

2015-07-28

A method is provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The method includes: monitoring a variable associated with at least one of the coolant-cooled cold plate or one or more electronic components being cooled by the cold plate; and dynamically varying, based on the monitored variable, a physical configuration of the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the one or more electronic components, and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the coolant-cooled cold plate, the positioning of which may be adjusted based on the monitored variable.

The Influence of the Inner Topology of Cooling Units on the Performance of Automotive Exhaust-Based Thermoelectric Generators

Science.gov (United States)

Zhu, D. C.; Su, C. Q.; Deng, Y. D.; Wang, Y. P.; Liu, X.

2018-06-01

Automotive exhaust-based thermoelectric generators are currently a hot topic in energy recovery. The waste heat of automotive exhaust gas can be converted into electricity by means of thermoelectric modules. Generally, inserting fins into the cooling unit contributes to enhancing the heat transfer for a higher power output. However, the introduction of fins will result in a pressure drop in the cooling system. In current research, in order to enhance the heat transfer and avoid a large pressure drop, a cooling unit with cylindrical grooves on the interior surface was proposed. To evaluate the performance of the cylindrical grooves, different inner topologies, including a smooth interior surface,a smooth interior surface with inserted fins and an interior surface with cylindrical grooves, were compared. The results revealed that compared with the smooth interior surface, the smooth interior surface with inserted fins and the interior surface with cylindrical grooves both enhanced the heat transfer, but the interior surface with cylindrical grooves obtained a lower pressure drop. To improve the performance of the cylindrical grooves, different groove-depth ratios were tried, and the results showed that a groove-depth ratio of 0.081 could provide the best overall performance.

A study of the external cooling capability for the prevention of reactor vessel failure

Energy Technology Data Exchange (ETDEWEB)

Chang, S H; Baek, W P; Moon, S K; Yang, S H; Kim, S H [Korea Advanced Institute of Science Technology, Daejeon (Korea, Republic of)

1994-07-15

This study (a 3-year program) aims to perform a comprehensive assessment of the feasibility of external vessel flooding with respect to advanced pressurized water reactor plants to be built in Korea. During the first year, review of the relevant phenomena and preliminary assessment of the concept have been performed. Also performed is a review of heat transfer correlations for the computer program that will be developed for assessment of the cooling capability of external vessel flooding. Important phenomena that determine the cooling capability of external vessel flooding are (a) the initial transient before formation of molten corium pool, (b) natural convection of in-vessel molten corium pool, (c) radiative heat exchange between the molten corium pool and the upper vessel structures, (d) thermal hydraulics outside the vessel, (e) structural integrity consideration, and (f) long-term phenomena. The adoption of the concept should be decided by considering several factors such as (a) vessel submergence procedure, (b) cooling requirements, (c) vessel design features, (d) steam production, (e) instrumentation needs, and (f) an overall accident management strategy. The external vessel cooling concept looks to be promising. However, further study is required for a reliable decision making. Several correlations are available for the prediction of cooling capability of the present concept. However, it is difficult to define a sufficiently reliable set of correlations; sensitivity studies would be required in assessing the cooling capability with the computer program.

Passive containment cooling system performance in the simplified boiling water reactor

International Nuclear Information System (INIS)

Shiralkar, B.S.; Gamble, R.E.; Yadigaroglu, G.

1997-01-01

The Simplified Boiling Water Reactor (SBWR) incorporates a passive system for decay heat removal from the containment in the event of a postulated Loss-of-Coolant Accident (LOCA). Decay heat is removed by condensation of the steam discharged from the reactor pressure vessel (RPV) in three condensers which comprise the Passive Containment Cooling System (PCCS). These condensers are designed to carry the heat load while transporting a mixture of steam and noncondensible gas (primarily nitrogen) from the drywell to the suppression chamber. This paper describes the expected LOCA response of the SBWR with respect to the PCCS performance, based on analysis and test results. The results confirm that the PCCS has excess capacity for decay heat removal and that overall system performance is very robust. 12 refs., 8 figs

On Innovative Cool-Colored Materials for Building Envelopes: Balancing the Architectural Appearance and the Thermal-Energy Performance in Historical Districts

Directory of Open Access Journals (Sweden)

Federica Rosso

2017-12-01

Full Text Available Architectural expression and energy performance are key decision-drivers in the selection of a particular construction element, with the purpose of Urban Heat Island mitigation, energy-consumption reductions, and cultural heritage preservation in historical centers. In historical centers, the external layer of the envelope and the visible parts of the building are built with traditional materials and technological solutions, such as single-layer walls or brickworks, depending on the country’s context, while the energy performance is usually optimized by means of internal insulation layers, or other active and passive solutions. Thermal-energy efficient materials and construction elements for the temperate, warm climate of the Mediterranean area are usually light-colored to reflect the largest part of solar radiation, thus reducing energy demands for cooling and improving thermal comfort conditions for occupants. On the other hand, many historical centers in such areas are characterized by reddish or grayish colors. In this work, we considered Italian historical areas, and other countries in the Mediterranean area with present similar situations. Thus, in this study, innovative, cool-colored, cement-based materials were developed to improve the thermal-energy performance of the external envelope of historical/historic built environments, without altering their appearance. These materials were prepared directly on-site, by mixing two types of pigments to achieve the desired color saturation. Optic and thermal properties were assessed, and yearly dynamic simulations of a historic, listed, case study building were performed, by comparing traditional-colored mortar and the prototype cool mortar envelopes. The research demonstrates that such cool-colored materials can maintain lower surface temperatures (−8 °C, while reducing energy demands for cooling (−3%.

Active cooling of a mobile phone handset

International Nuclear Information System (INIS)

Grimes, Ronan; Walsh, Ed; Walsh, Pat

2010-01-01

Power dissipation levels in mobile phones continue to increase due to gaming, higher power applications, and increased functionality associated with the internet. The current cooling methodologies of natural convection and radiation limit the power dissipation within a mobile phone to between 1-2 W depending on size. As power dissipation levels increase, products such as mobile phones will require active cooling to ensure that the devices operate within an acceptable temperature envelop from both user comfort and reliability perspectives. In this paper, we focus on the applied thermal engineering problem of an active cooling solution within a typical mobile phone architecture by implementing a custom centrifugal fan within the mobile phone. Its performance is compared in terms of flow rates and pressure drops, allowable phone heat dissipation and maximum phone surface temperature as this is the user constraint for a variety of simulated PCB architectures in the mobile phone. Perforated plates with varying porosity through different size orifices are used to simulate these architectures. The results show that the power level dissipated by a phone for a constant surface temperature may be increased by ∼50 - 75% depending on pressure drop induced by the internal phone architecture. Hence for successful implementation and efficient utilization of active cooling will require chip layout to be considered at the design stage.

Thermal-hydraulic performance of a multiple jet cooling module with a concave dimple array in a helium-cooled divertor

Energy Technology Data Exchange (ETDEWEB)

Jung, Hyo-Yeon; Kim, Kwang-Yong, E-mail: kykim@inha.ac.kr

2017-01-15

A numerical study was performed to evaluate the thermal-hydraulic performance of a finger type cooling module, where multiple jets impinge on the surface with concave dimples, in the divertor of a nuclear fusion reactor. Conjugate heat transfer was analyzed in both the solid and fluid domains using three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. The computational domain consisted of a single fluid domain and three solid domains: tile, thimble, and cartridge. The numerical results for the temperature variation on the tile were validated in comparison with the experimental data. A parametric study was performed with two design variables, the ratios of dimple diameter and dimple height to the nozzle diameter, and two dimple arrays (inline and staggered arrays). The parametric study showed that the heat transfer rate was increased by up to 2.62% by introducing concave dimples, and that the heat transfer and pressure drop performances increased with increasing diameter and height of the dimples for a specified dimple array.

Performance Estimation of Supercritical Co2 Micro Modular Reactor (MMR) for Varying Cooling Air Temperature

International Nuclear Information System (INIS)

Ahn, Yoonhan; Kim, Seong Gu; Cho, Seong Kuk; Lee, Jeong Ik

2015-01-01

A Small Modular Reactor (SMR) receives interests for the various application such as electricity co-generation, small-scale power generation, seawater desalination, district heating and propulsion. As a part of SMR development, supercritical CO2 Micro Modular Reactor (MMR) of 36.2MWth in power is under development by the KAIST research team. To enhance the mobility, the entire system including the power conversion system is designed for the full modularization. Based on the preliminary design, the thermal efficiency is 31.5% when CO2 is sufficiently cooled to the design temperature. A supercritical CO2 MMR is designed to supply electricity to the remote regions. The ambient temperature of the area can influence the compressor inlet temperature as the reactor is cooled with the atmospheric air. To estimate the S-CO2 cycle performance for various environmental conditions, A quasi-static analysis code is developed. For the off design performance of S-CO2 turbomachineries, the experimental result of Sandia National Lab (SNL) is utilized

Comparison of solar panel cooling system by using dc brushless fan and dc water

International Nuclear Information System (INIS)

Irwan, Y M; Leow, W Z; Irwanto, M; M, Fareq; Hassan, S I S; Amelia, A R; Safwati, I

2015-01-01

The purpose of this article is to discuss comparison of solar panel cooling system by using DC brushless fan and DC water pump. Solar photovoltaic (PV) power generation is an interesting technique to reduce non-renewable energy consumption and as a renewable energy. The temperature of PV modules increases when it absorbs solar radiation, causing a decrease in efficiency. A solar cooling system is design, construct and experimentally researched within this work. To make an effort to cool the PV module, Direct Current (DC) brushless fan and DC water pump with inlet/outlet manifold are designed for constant air movement and water flow circulation at the back side and front side of PV module representatively. Temperature sensors were installed on the PV module to detect temperature of PV. PIC microcontroller was used to control the DC brushless fan and water pump for switch ON or OFF depend on the temperature of PV module automatically. The performance with and without cooling system are shown in this experiment. The PV module with DC water pump cooling system increase 3.52%, 36.27%, 38.98%in term of output voltage, output current, output power respectively. It decrease 6.36 °C compare than to PV module without DC water pump cooling system. While DC brushless fan cooling system increase 3.47%, 29.55%, 32.23%in term of output voltage, output current, and output power respectively. It decrease 6.1 °C compare than to PV module without DC brushless fan cooling system. The efficiency of PV module with cooling system was increasing compared to PV module without cooling system; this is because the ambient temperature dropped significantly. The higher efficiency of PV cell, the payback period of the system can be shorted and the lifespan of PV module can also be longer. (paper)

Dry well cooling device

International Nuclear Information System (INIS)

Suzuki, Hiroyuki.

1997-01-01

A plurality of blowing ports with introduction units are disposed to a plurality of ducts in a dry well, and a cooling unit comprising a cooler, a blower and an isolating valve is disposed outside of the dry well. Cooling air and the atmosphere in the dry well are mixed to form a cooling gas and blown into the dry well to control the temperature. Since the cooling unit is disposed outside of the dry well, the maintenance of the cooling unit can be performed even during the plant operation. In addition, since dampers opened/closed depending on the temperature of the atmosphere are disposed to the introduction units for controlling the temperature of the cooling gas, the temperature of the atmosphere in the dry well can be set to a predetermined level rapidly. Since an axial flow blower is used as the blower of the cooling unit, it can be contained in a ventilation cylinder. Then, the atmosphere in the dry well flowing in the ventilation cylinder can be prevented from leaking to the outside. (N.H.)

Techno-economic studies on hybrid energy based cooling system for milk preservation in isolated regions

International Nuclear Information System (INIS)

Edwin, M.; Joseph Sekhar, S.

2014-01-01

Highlights: • Performance studies on biomass and biogas based milk cooling systems in remote areas. • Economic analysis of milk cooling system operated with locally available renewable energy sources. • Payback period for replacing conventional milk cooling systems with renewable energy based cooling system. • Identification of the suitable combination of locally available renewable energy sources for milk cooling. • Hybrid energy based milk cooling system for regions that have rubber and paddy cultivation, in India. - Abstract: In developing countries like India, about 70% of the population is engaged in the production of milk, fruits and vegetables. Due to the lack of proper storage and transit facilities, the agricultural produce, in remote areas loses its value. This spoilage could be prevented at the local village level, by providing cooling units for short term preservation. In this paper, the possibility of a hybrid energy based thermally operated cold storage has been considered to meet the cooling needs of the villages in the southern parts of India, where biomass, biogas and gobar gas are available in abundance. A milk cooling system that uses various combinations of locally available renewable energy sources to operate an aqua ammonia vapour absorption cooling system has been analysed using the Matlab software. The impact of various combinations of renewable energy sources on the Coefficient of Performance (COP), Net Present Value (NPV) and payback period of the total cooling system has been studied. The analysis shows that the COP and payback period of the proposed hybrid renewable energy based milk cooling system are 0.16–0.23 and 4–6 years respectively

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 ...

Short-term memory and dual task performance

Science.gov (United States)

Regan, J. E.

1982-01-01

Two hypotheses concerning the way in which short-term memory interacts with another task in a dual task situation are considered. It is noted that when two tasks are combined, the activity of controlling and organizing performance on both tasks simultaneously may compete with either task for a resource; this resource may be space in a central mechanism or general processing capacity or it may be some task-specific resource. If a special relationship exists between short-term memory and control, especially if there is an identity relationship between short-term and a central controlling mechanism, then short-term memory performance should show a decrement in a dual task situation. Even if short-term memory does not have any particular identity with a controlling mechanism, but both tasks draw on some common resource or resources, then a tradeoff between the two tasks in allocating resources is possible and could be reflected in performance. The persistent concurrence cost in memory performance in these experiments suggests that short-term memory may have a unique status in the information processing system.

Stochastic cooling technology at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Pasquinelli, R.J. E-mail: pasquin@fnal.gov

2004-10-11

The first antiproton cooling systems were installed and commissioned at Fermilab in 1984-1985. In the interim period, there have been several major upgrades, system improvements, and complete reincarnation of cooling systems. This paper will present some of the technology that was pioneered at Fermilab to implement stochastic cooling systems in both the Antiproton Source and Recycler accelerators. Current performance data will also be presented.

Stochastic cooling technology at Fermilab

Science.gov (United States)

Pasquinelli, Ralph J.

2004-10-01

The first antiproton cooling systems were installed and commissioned at Fermilab in 1984-1985. In the interim period, there have been several major upgrades, system improvements, and complete reincarnation of cooling systems. This paper will present some of the technology that was pioneered at Fermilab to implement stochastic cooling systems in both the Antiproton Source and Recycler accelerators. Current performance data will also be presented.

Stochastic cooling technology at Fermilab

International Nuclear Information System (INIS)

Pasquinelli, R.J.

2004-01-01

The first antiproton cooling systems were installed and commissioned at Fermilab in 1984-1985. In the interim period, there have been several major upgrades, system improvements, and complete reincarnation of cooling systems. This paper will present some of the technology that was pioneered at Fermilab to implement stochastic cooling systems in both the Antiproton Source and Recycler accelerators. Current performance data will also be presented

Thermal performance analysis of heat exchanger for closed wet cooling tower using heat and mass transfer analogy

International Nuclear Information System (INIS)

Yoo, Seong Yeon; Han, Kyu Hyun; Kim, Jin Hyuck

2010-01-01

In closed wet cooling towers, the heat transfer between the air and external tube surfaces can be composed of the sensible heat transfer and the latent heat transfer. The heat transfer coefficient can be obtained from the equation for external heat transfer of tube banks. According to experimental data, the mass transfer coefficient was affected by the air velocity and spray water flow rate. This study provides the correlation equation for mass transfer coefficient based on the analogy of the heat and mass transfer and the experimental data. The results from this correlation equation showed fairly good agreement with experimental data. The cooling capacity and thermal efficiency of the closed wet cooling tower were calculated from the correlation equation to analyze the performance of heat exchanger for the tower

Optimizing cooling tower performance refrigeration systems, chemical plants, and power plants all have a resource quietly awaiting exploitation - cold water

International Nuclear Information System (INIS)

Burger, R.

1993-01-01

The cooling towers are hidden bonanzas for energy conservation and dollar savings when properly engineered and maintained. In many cases, the limiting factor of production is the quality and quantity of cold water coming off the cooling tower. The savings accrued in energy conservation and additional product manufactured can be an important factor on the operator's company's profit and loss sheet (7). Energy management analysis is a very important consideration in today's escalating climate of costs of energy. It is advisable to consider a thorough engineering inspection and evaluation of the entire plant to leave no stone unturned iii the search to reduce energy consumption (8). The cooling tower plays the major role on waste heat removal and should be given a thorough engineering inspection and evaluation by a specialist in this field. This can be performed at nominal cost and a formal report submitted with recommendations, budget costs, and evaluation of the thermal, structural, and mechanical condition of the equipment. This feasibility study will assist in determining the extent of efficiency improvement available with costs and projected savings. It can be stated that practically all cooling towers can be upgraded to perform at higher levels of efficiency which can provide a rapid, cost-effective payback. However, while all cooling tower systems might not provide such a dramatic cost payback as these case histories, the return of a customer's investment in upgrading his cooling tower can be a surprising factor of operation and should not be neglected

Stochastic cooling

International Nuclear Information System (INIS)

Bisognano, J.; Leemann, C.

1982-03-01

Stochastic cooling is the damping of betatron oscillations and momentum spread of a particle beam by a feedback system. In its simplest form, a pickup electrode detects the transverse positions or momenta of particles in a storage ring, and the signal produced is amplified and applied downstream to a kicker. The time delay of the cable and electronics is designed to match the transit time of particles along the arc of the storage ring between the pickup and kicker so that an individual particle receives the amplified version of the signal it produced at the pick-up. If there were only a single particle in the ring, it is obvious that betatron oscillations and momentum offset could be damped. However, in addition to its own signal, a particle receives signals from other beam particles. In the limit of an infinite number of particles, no damping could be achieved; we have Liouville's theorem with constant density of the phase space fluid. For a finite, albeit large number of particles, there remains a residue of the single particle damping which is of practical use in accumulating low phase space density beams of particles such as antiprotons. It was the realization of this fact that led to the invention of stochastic cooling by S. van der Meer in 1968. Since its conception, stochastic cooling has been the subject of much theoretical and experimental work. The earliest experiments were performed at the ISR in 1974, with the subsequent ICE studies firmly establishing the stochastic cooling technique. This work directly led to the design and construction of the Antiproton Accumulator at CERN and the beginnings of p anti p colliding beam physics at the SPS. Experiments in stochastic cooling have been performed at Fermilab in collaboration with LBL, and a design is currently under development for a anti p accumulator for the Tevatron

CO_2-assisted compression-adsorption hybrid for cooling and desalination

International Nuclear Information System (INIS)

Ali, Syed Muztuza; Chakraborty, Anutosh; Leong, Kai Choong

2017-01-01

Highlights: • Amalgamation of vapour compression and adsorption. • Thermodynamic frameworks of compression-adsorption hybrid. • 60% improvement in COP as compared with conventional CO_2 cooling system. • Energy recovery from CO_2 is used for cooling and desalination. • Energy from gas cooler accelerates the desalination process. - Abstract: This paper presents a novel compression-adsorption hybrid that symbiotically combines adsorption and CO_2 compression cooling devices. The seemingly low efficiency of each cycle individually is overcome by an amalgamation with the other. Hence, both heat and water vapour refrigerant mass are recovered for continuous cooling and desalination. Two different configurations are presented. The first configuration deals with a two-stage heat recovery system. At the first stage, heat is recovered from the compressed carbon dioxide to drive the adsorption device. The second stage heat recovery system internally exchanges heat between the low pressure and high pressure refrigerants of the CO_2 cycle. The second configuration is proposed with an additional third-stage heat recovery from the gas cooler to the high pressure evaporator of the adsorption cycle. The water vapour mass is recovered from bed-to-bed adsorption at relatively higher pressure. A detailed thermodynamic framework is presented to simulate the performances in terms of COP (coefficient of performance), SCP (specific cooling power), SDWP (specific daily water production), PR (performance ratio) and OCR (overall conversion ratio). It is found that the overall COP is improved by more than 60% as compared to the conventional CO_2 cycle, and in addition, the system generates 12.7 m"3 of desalinated water per tonne of silica gel per day as extra benefits. Furthermore, both the heat and mass recoveries improve the overall conversion ratio, which is almost double as compared to the conventional CO_2 cycle.

A powerful way of cooling computer chip using liquid metal with low melting point as the cooling fluid

Energy Technology Data Exchange (ETDEWEB)

Li Teng; Lv Yong-Gang [Chinese Academy of Sciences, Beijing (China). Cryogenic Lab.; Chinese Academy of Sciences, Beijing (China). Graduate School; Liu Jing; Zhou Yi-Xin [Chinese Academy of Sciences, Beijing (China). Cryogenic Lab.

2006-12-15

With the improvement of computational speed, thermal management becomes a serious concern in computer system. CPU chips are squeezing into tighter and tighter spaces with no more room for heat to escape. Total power-dissipation levels now reside about 110 W, and peak power densities are reaching 400-500 W/mm{sup 2} and are still steadily climbing. As a result, higher performance and greater reliability are extremely tough to attain. But since the standard conduction and forced-air convection techniques no longer be able to provide adequate cooling for sophisticated electronic systems, new solutions are being looked into liquid cooling, thermoelectric cooling, heat pipes, and vapor chambers. In this paper, we investigated a novel method to significantly lower the chip temperature using liquid metal with low melting point as the cooling fluid. The liquid gallium was particularly adopted to test the feasibility of this cooling approach, due to its low melting point at 29.7 C, high thermal conductivity and heat capacity. A series of experiments with different flow rates and heat dissipation rates were performed. The cooling capacity and reliability of the liquid metal were compared with that of the water-cooling and very attractive results were obtained. Finally, a general criterion was introduced to evaluate the cooling performance difference between the liquid metal cooling and the water-cooling. The results indicate that the temperature of the computer chip can be significantly reduced with the increasing flow rate of liquid gallium, which suggests that an even higher power dissipation density can be achieved with a large flow of liquid gallium and large area of heat dissipation. The concept discussed in this paper is expected to provide a powerful cooling strategy for the notebook PC, desktop PC and large computer. It can also be extended to more wide area involved with thermal management on high heat generation rate. (orig.)

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.

Heavy water moderated gas-cooled reactors

International Nuclear Information System (INIS)

Bailly du Bois, B.; Bernard, J.L.; Naudet, R.; Roche, R.

1964-01-01

France has based its main effort for the production of nuclear energy on natural Uranium Graphite-moderated gas-cooled reactors, and has a long term programme for fast reactors, but this country is also engaged in the development of heavy water moderated gas-cooled reactors which appear to present the best middle term prospects. The economy of these reactors, as in the case of Graphite, arises from the use of natural or very slightly enriched Uranium; heavy water can take the best advantages of this fuel cycle and moreover offers considerable development potential because of better reactor performances. A prototype plant EL 4 (70 MW) is under construction and is described in detail in another paper. The present one deals with the programme devoted to the development of this reactor type in France. Reasons for selecting this reactor type are given in the first part: advantages and difficulties are underlined. After reviewing the main technological problems and the Research and Development carried out, results already obtained and points still to be confirmed are reported. The construction of EL 4 is an important step of this programme: it will be a significant demonstration of reactor performances and will afford many experimentation opportunities. Now the design of large power reactors is to be considered. Extension and improvements of the mechanical structures used for EL 4 are under study, as well as alternative concepts. The paper gives some data for a large reactor in the present state of technology, as a result from optimization studies. Technical improvements, especially in the field of materials could lead to even more interesting performances. Some prospects are mentioned for the long run. Investment costs and fuel cycles are discussed in the last part. (authors) [fr

Assessing energy and thermal comfort of different low-energy cooling concepts for non-residential buildings

International Nuclear Information System (INIS)

Salvalai, Graziano; Pfafferott, Jens; Sesana, Marta Maria

2013-01-01

Highlights: • Impact of five cooling technologies are simulated in six European climate zones with Trnsys 17. • The ventilation strategies reduce the cooling energy need even in South Europe climate. • Constant ventilation controller can lead to a poor cooling performance. • Comparing radiant strategies with air conditioning scenario, the energy saving is predicted to within 5–35%. - Abstract: Energy consumption for cooling is growing dramatically. In the last years, electricity peak consumption grew significantly, switching from winter to summer in many EU countries. This is endangering the stability of electricity grids. This article outlines a comprehensive analysis of an office building performances in terms of energy consumption and thermal comfort (in accordance with static – ISO 7730:2005 – and adaptive thermal comfort criteria – EN 15251:2007 –) related to different cooling concepts in six different European climate zones. The work is based on a series of dynamic simulations carried out in the Trnsys 17 environment for a typical office building. The simulation study was accomplished for five cooling technologies: natural ventilation (NV), mechanical night ventilation (MV), fan-coils (FC), suspended ceiling panels (SCP), and concrete core conditioning (CCC) applied in Stockholm, Hamburg, Stuttgart, Milan, Rome, and Palermo. Under this premise, the authors propose a methodology for the evaluation of the cooling concepts taking into account both, thermal comfort and energy consumption

Cooling performance and evaluation of automotive refrigeration system for a passenger car

Science.gov (United States)

Prajitno, Deendarlianto, Majid, Akmal Irfan; Mardani, Mahardeka Dhias; Wicaksono, Wendi; Kamal, Samsul; Purwanto, Teguh Pudji; Fauzun

2016-06-01

A new design of automotive refrigeration system for a passenger car was proposed. To ensure less energy consumption and optimal thermal comfort, the performance of the system were evaluated. This current research was aimed to evaluate the refrigeration characteristics of the system for several types of cooling load. In this present study, a four-passenger wagon car with 1500 cc gasoline engine that equipped by a belt driven compressor (BDC) was used as the tested vehicle. To represent the tropical condition, a set of lamps and wind sources are installed around the vehicle. The blower capacity inside a car is varied from 0.015 m/s to 0.027 m/s and the compressor speed is varied at variable 820, 1400, and 2100 rpm at a set temperature of 22°C. A set of thermocouples that combined by data logger were used to measure the temperature distribution. The system uses R-134a as the refrigerant. In order to determine the cooling capacity of the vehicle, two conditions were presented: without passengers and full load conditions. As the results, cooling capacity from any possible heating sources and transient characteristics of temperature in both systems for the cabin, engine, compressor, and condenser are presented in this work. As the load increases, the outlet temperature of evaporator also increases due to the increase of condensed air. This phenomenon also causes the increase of compressor work and compression ratio which associated to the addition of specific volume in compressor inlet.

Workshop on beam cooling and related topics

International Nuclear Information System (INIS)

Bosser, J.

1994-01-01

The sessions of the Workshop on Beam Cooling and Related Topics, held in Montreux from 4-8 October 1993, are reported in these Proceedings. This meeting brought together international experts in the field of accelerator beam cooling. Its purpose was to discuss the status of the different cooling techniques currently in use (stochastic, electron, ionization, heavy-ion, and laser) and their actual performances, technological implications, and future prospects. Certain theoretical principles (muon cooling, cyclotron maser cooling) were discussed and are reported on in these Proceedings. Also of interest in this Workshop was the possibility of beam crystallization in accelerators using ultimate cooling. In the first part of these Proceedings, overview talks on the various cooling techniques, their implications, present performance, and future prospects are presented. More detailed reports on all the topics are then given in the form of oral presentations or poster sessions. Finally, the chairmen and/or convenors then present summary talks. (orig.)

Computational Analysis of Droplet Mass and Size Effect on Mist/Air Impingement Cooling Performance

Directory of Open Access Journals (Sweden)

Zhenglei Yu

2013-01-01

Full Text Available Impingement cooling has been widely employed to cool gas turbine hot components such as combustor liners, combustor transition pieces, turbine vanes, and blades. A promising technology is proposed to enhance impingement cooling with water droplets injection. However, previous studies were conducted on blade shower head film cooling, and less attention was given to the transition piece cooling. As a continuous effort to develop a realistic mist impingement cooling scheme, this paper focuses on simulating mist impingement cooling under typical gas turbine operating conditions of high temperature and pressure in a double chamber model. Furthermore, the paper presents the effect of cooling effectiveness by changing the mass and size of the droplets. Based on the heat-mass transfer analogy, the results of these experiments prove that the mass of 3E – 3 kg/s droplets with diameters of 5–35 μm could enhance 90% cooling effectiveness and reduce 122 K of wall temperature. The results of this paper can provide guidance for corresponding experiments and serve as the qualification reference for future more complicated studies with convex surface cooling.

Melt cooling by bottom flooding. The COMET core-catcher concept

International Nuclear Information System (INIS)

Foit, Jerzy Jan; Alsmeyer, Hans; Tromm, Walter; Buerger, Manfred; Journeau, Christophe

2009-01-01

The COMET concept has been developed to cool an ex-vessel corium melt in case of a hypothetical severe accident leading to vessel melt-through. After erosion of a sacrificial concrete layer the melt is passively flooded by bottom injection of coolant water. The open porosities and large surface that are generated during melt solidification form a porous permeable structure that is permanently filled with the evaporating water and thus allows an efficient short-term as well as long-term removal of the decay heat. The advantages of this concept are the fast cool-down and complete solidification of the melt within less than one hour typically. This stops further release of fission products from the corium. A drawback may be the fast release of steam during the quenching process. Several experimental series have been performed by FZK (Germany) to test and optimise the functionality of the different variants of the COMET concept. Thermite generated melts of iron and aluminium oxide were used. The large scale COMET-H test series with sustained inductive heating includes nine experiments performed with an array of water injection channels embedded in a sacrificial concrete layer. Variation of the water inlet pressure and melt height showed that melts up to 50 cm height can be safely cooled with an overpressure of the coolant water of 0.2 bar. The CometPC concept is based on cooling by flooding the melt from the bottom through layers of porous, water filled concrete. The third variant of the COMET design, CometPCA, uses a layer of porous, water filled concrete CometPCA from which flow channels protrude into the layer of sacrificial concrete. This modified concept combines the advantages of the original COMET concept with flow channels and the high resistance of a water-filled porous concrete layer against downward melt attack. Four large scale CometPCA experiments (FZK, Germany) have demonstrated an efficient cooling of melts up to 50 cm height using the recommended water

Performance analysis of ventilation systems with desiccant wheel cooling based on exergy destruction

International Nuclear Information System (INIS)

Tu, Rang; Liu, Xiao-Hua; Hwang, Yunho; Ma, Fei

2016-01-01

Highlights: • Ventilation systems with desiccant wheel were analyzed from exergy destruction. • Main performances influencing factors for ventilation systems are put forward. • Improved ventilation systems with lower exergy destruction are suggested. • Performances of heat pumps driven ventilation systems are greatly increased. - Abstract: This paper investigates the performances of ventilation systems with desiccant wheel cooling from the perspective of exergy destructions. Based on the inherent influencing factors for exergy destructions of heat and mass transfer and heat sources, provide guidelines for efficient system design. First, performances of a basic ventilation system are simulated, which is operated at high regeneration temperature and low coefficient of performance (COP). Then, exergy analysis of the basic ventilation system shows that exergy destructions mainly exist in the heat and mass transfer components and the heat source. The inherent influencing factors for the heat and mass transfer exergy destruction are heat and mass transfer capacities, which are related to over dehumidification of the desiccant wheel, and unmatched coefficients, which represent the uniformity of the temperature or humidity ratio differences fields for heat and mass transfer components. Based on these findings, two improved ventilation systems are suggested. For the first system, over dehumidification is avoided and unmatched coefficients for each component are reduced. With lower heat and mass transfer exergy destructions and lower regeneration temperature, COP and exergy efficiency of the first system are increased compared with the basic ventilation system. For the second system, a heat pump, which recovers heat from the process air to heat the regeneration air, is adopted to replace the electrical heater and cooling devices. The exergy destruction of the heat pump is considerably reduced as compared with heat source exergy destruction of the basic ventilation

Performance evaluation of micro thermoelectric module for hot spot cooling

International Nuclear Information System (INIS)

Kim, Ook Joong; Lee, Kong Hoon

2008-01-01

The experimental and numerical study is carried out to investigate the availability of micro TEM for hot spot cooling of an IC chip. It is found that an acrylic plate integrating with copper plate and imbedded micro TEM represents good hot spot cooling of the IC chip when CO2 laser is used to hot spot heating. Effective active local cooling phenomena by the TEM are well investigated by experiment. The measured temperature drop in the hot spot point is compared to numerical result using the TAS program for every case. Numerical result shows good agreement with experiment using some appropriate thermal and thermoelectric properties of TEM and TIM obtained by trial and error. Measurement of thermo-physical properties such as contact thermal resistance and thickness of liquid TIM is difficult but can be estimated by numerical analysis

Optimization of distribution piping network in district cooling system using genetic algorithm with local search

International Nuclear Information System (INIS)

Chan, Apple L.S.; Hanby, Vic I.; Chow, T.T.

2007-01-01

A district cooling system is a sustainable means of distribution of cooling energy through mass production. A cooling medium like chilled water is generated at a central refrigeration plant and supplied to serve a group of consumer buildings through a piping network. Because of the substantial capital investment involved, an optimal design of the distribution piping configuration is one of the crucial factors for successful implementation of the district cooling scheme. In the present study, genetic algorithm (GA) incorporated with local search techniques was developed to find the optimal/near optimal configuration of the piping network in a hypothetical site. The effect of local search, mutation rate and frequency of local search on the performance of the GA in terms of both solution quality and computation time were investigated and presented in this paper

performance evaluation of a composite-padded evaporative cooling

African Journals Online (AJOL)

user

average temperature drop and saturation efficiency in the evaporative cooler during the no-load test were 5°C and 42%, ... flow rate wetting the pad and the construction material .... principle of evaporation which results in a cooling effect.

Numerical study on the performance of vacuum cooler and evaporation-boiling phenomena during vacuum cooling of cooked meat

International Nuclear Information System (INIS)

Jin, T.X.; Xu, L.

2006-01-01

The vacuum cooling of cooked meats is described in this paper. Based on the energy and mass balance, a modified mathematical model based on a previous model is developed to analyze the performance of the vacuum cooler and the evaporation-boiling phenomena during vacuum cooling of cooked meat. Validation experimentation is performed in the designed vacuum cooler. Boiling occurs inside the cooked meat. There is a boiling front, and the boiling front moves toward the center of the cooked meat as the vacuum cooling proceeds. The experimental data are compared with the simulation results. It is found that the differences of the temperature between the simulation and the experimentation are within 5 deg. C, and the deviation of weight loss between the simulation and the experimentation is within 4%. The simulation results agree with the experimental data well. The modified model can be used to predict the variation of the vacuum pressure in the chamber, the temperature and pressure distributions and the weight loss profiles of cylindrical cooked meats

Numerical examination of temperature control in helium-cooled high flux test module of IFMIF

International Nuclear Information System (INIS)

Ebara, Shinji; Yokomine, Takehiko; Shimizu, Akihiko

2007-01-01

For long term irradiation of the International Fusion Materials Irradiation Facility (IFMIF), test specimens are needed to retain constant temperature to avoid change of its irradiation characteristics. The constant temperatures control is one of the most challenging issues for the IFMIF test facilities. We have proposed a new concept of test module which is capable of precisely measuring temperature, keeping uniform temperature with enhanced cooling performance. In the system according to the new design, cooling performances and temperature distributions of specimens were examined numerically under diverse conditions. Some transient behaviors corresponding to the prescribed temperature control mode were perseveringly simulated. It was confirmed that the thermal characteristics of the new design satisfied the severe requirement of IFMIF

Storage of HLW in engineered structures: air-cooled and water-cooled concepts

International Nuclear Information System (INIS)

Ahner, S.; Dekais, J.J.; Puttke, B.; Staner, P.

1981-01-01

A comparative study on an air-cooled and a water-cooled intermediate storage of vitrified, highly radioactive waste (HLW) in overground installations has been performed by Nukem and Belgonucleaire respectively. In the air-cooled storage concept the decay heat from the storage area will be removed using natural convection. In the water-cooled storage concept the decay heat is carried off by a primary and secondary forced-cooling system with redundant and diverse devices. The safety study carried out by Nukem used a fault tree method. It shows that the reliability of the designed water-cooled system is very high and comparable to the inherent, safe, air-cooled system. The impact for both concepts on the environment is determined by the release route, but even during accident conditions the release is far below permissible limits. The economic analysis carried out by Belgonucleaire shows that the construction costs for both systems do not differ very much, but the operation and maintenance costs for the water-cooled facility are higher than for the air cooled facility. The result of the safety and economic analysis and the discussions with the members of the working group have shown some possible significant modifications for both systems, which are included in this report. The whole study has been carried out using certain national criteria which, in certain Member States at least, would lead to a higher standard of safety than can be justified on any social, political or economic grounds

3-Dimensional numerical study of cooling performance of a heat sink with air-water flow through mini-channel

Science.gov (United States)

Majumder, Sambit; Majumder, Abhik; Bhaumik, Swapan

2016-07-01

The present microelectronics market demands devices with high power dissipation capabilities having enhanced cooling per unit area. The drive for miniaturizing the devices to even micro level dimensions is shooting up the applied heat flux on such devices, resulting in complexity in heat transfer and cooling management. In this paper, a method of CPU processor cooling is introduced where active and passive cooling techniques are incorporated simultaneously. A heat sink consisting of fins is designed, where water flows internally through the mini-channel fins and air flows externally. Three dimensional numerical simulations are performed for large set of Reynolds number in laminar region using finite volume method for both developing flows. The dimensions of mini-channel fins are varied for several aspect ratios such as 1, 1.33, 2 and 4. Constant temperature (T) boundary condition is applied at heat sink base. Channel fluid temperature, pressure drop are analyzed to obtain best cooling option in the present study. It has been observed that as the aspect ratio of the channel decreases Nusselt number decreases while pressure drop increases. However, Nusselt number increases with increase in Reynolds number.

External Reactor Vessel Cooling Evaluation for Severe Accident Mitigation in NPP Krsko

International Nuclear Information System (INIS)

Mihalina, M.; Spalj, S.; Glaser, B.

2016-01-01

The In-Vessel corium Retention (IVR) through the External Reactor Vessel Cooling (ERVC) is mean for maintaining the reactor vessel integrity during a severe accident, by cooling and retaining the molten material inside the reactor vessel. By doing this, significant portion of severe accident negative phenomena connected with reactor vessel failure could be avoided. In this paper, analysis of NPP Krsko applicability for IVR strategy was performed. It includes overview of performed plant related analysis with emphasis on wet cavity modification, plant's site specific walk downs, new applicable probabilistic and deterministic analysis, evaluation of new possibilities for ERVC strategy implementation regarding plant's post-Fukushima improvements and adequacy with plant's procedures for severe accident mitigation. Conclusion is that NPP Krsko could perform in-vessel core retention by applying external reactor vessel cooling strategy with reasonable confidence in success. Per probabilistic and deterministic analysis, time window for successful ERVC strategy performance for most dominating plant damage state scenarios is 2.5 hours, when onset of core damage is observed. This action should be performed early after transition to Severe Accident Management Guidance's (SAMG). For loss of all AC power scenario, containment flooding could be initiated before onset of core damage within related emergency procedure. To perform external reactor vessel cooling, reactor water storage tank gravity drain with addition of alternate water is needed to be injected into the containment. ERVC strategy will positively interfere with other severe accident strategies. There are no negative effects due to ERVC performance. New flooding level will not threaten equipment and instrumentation needed for long term SAMGs performance and eventually diluted containment sump borated water inventory will not cause return to criticality during eventual recirculation phase due to the

Semioptimal practicable algorithmic cooling

International Nuclear Information System (INIS)

Elias, Yuval; Mor, Tal; Weinstein, Yossi

2011-01-01

Algorithmic cooling (AC) of spins applies entropy manipulation algorithms in open spin systems in order to cool spins far beyond Shannon's entropy bound. Algorithmic cooling of nuclear spins was demonstrated experimentally and may contribute to nuclear magnetic resonance spectroscopy. Several cooling algorithms were suggested in recent years, including practicable algorithmic cooling (PAC) and exhaustive AC. Practicable algorithms have simple implementations, yet their level of cooling is far from optimal; exhaustive algorithms, on the other hand, cool much better, and some even reach (asymptotically) an optimal level of cooling, but they are not practicable. We introduce here semioptimal practicable AC (SOPAC), wherein a few cycles (typically two to six) are performed at each recursive level. Two classes of SOPAC algorithms are proposed and analyzed. Both attain cooling levels significantly better than PAC and are much more efficient than the exhaustive algorithms. These algorithms are shown to bridge the gap between PAC and exhaustive AC. In addition, we calculated the number of spins required by SOPAC in order to purify qubits for quantum computation. As few as 12 and 7 spins are required (in an ideal scenario) to yield a mildly pure spin (60% polarized) from initial polarizations of 1% and 10%, respectively. In the latter case, about five more spins are sufficient to produce a highly pure spin (99.99% polarized), which could be relevant for fault-tolerant quantum computing.