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Sample records for vapour compression refrigeration

  1. Refrigerants for Vapour Compression Refrigeration Systems

    Indian Academy of Sciences (India)

    ; global warming; CFC; HCFC; HFC; HFO; zeotropic mixture; natural fluids. Author Affiliations. G Venkatarathnam1 S Srinivasa Murthy1. Refrigeration and Airconditioning Laboratory, Department of Mechanical Engineering, Indian Institute of ...

  2. Refrigerants for Vapour Compression Refrigeration Systems

    Indian Academy of Sciences (India)

    With the mandate of Montreal Protocol banning ozone de- pleting substances, and Kyoto Protocol later on curtailing the use of substances which contribute to global warming, con- ventional refrigerants are to be replaced by environment- friendly working fluids. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons ...

  3. Design and Simulation of a Vapour Compression Refrigeration System Using Phase Change Material

    Directory of Open Access Journals (Sweden)

    Siddharth Raju

    2018-01-01

    Full Text Available The paper details the design and simulation of a solar powered vapour compression refrigeration system. The effect of a phase change material, in this case ice, on a vapour compression refrigeration system powered by solar panels is discussed. The battery and solar panels were sized to allow the system to function as an autonomous unit for a minimum of 12 hours. It was concluded that the presence of a phase change material in the refrigeration system caused a considerable increase in both the on and off time of the compressor. The ratio by which the on time increased was greater than the ratio by which the off time was increased. There was a 219% increase in the on time, a 139% increase in the compressor off time and a 3.5% increase in compressor work accompanied by a 5.5% reduction in COP. Thus, under conditions where there is enough load in the system to cause the initial on and off times of the compressor to be comparable, the presence of a phase change material may result in a greater on period than an off period for the compressor.

  4. COP Prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning

    Directory of Open Access Journals (Sweden)

    Nat Suvarnakuta

    2014-03-01

    Full Text Available This paper presents the COP prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning. Using computational fluid dynamics (CFD technique, the performance of an ejector was analyzed in term of the entrainment ratio (Rm and critical back pressure (CBP. The results from this study were compared with a previous study of combined ejector refrigeration system for automotive air conditioning application [1] which the entrainment ratio (Rm were predicted from one-dimensional (1-D equation. The performance of an ejector (Rm and CBP from CFD and onedimensional method were analyzed and used as database for a mathematical modeling. In order to predict the COP of the combined system, a set of mathematical equations was developed using EES. The operating conditions are chosen accordingly as, intercooler temperature between 15 ๐ C and 25 ๐ C, condenser temperature equal to 35 ๐ C and evaporator temperature equal to 5 ๐ C. However, when generator temperatures are 80 ๐ C, 85 ๐ C and 90 ๐ C, the results showed average relative errors of the COP of an ejector refrigeration cycle (COPej, between CFD and 1-D are 44.64%, 50.47% and 59.68% respectively, and between CFD and 1-D NEW are 1.54%, 0.08% and 6.49% respectively.

  5. Performance of A Vapour Compression Heat Pump System Using A Nonazeotropic Refrigerant Mixture

    Science.gov (United States)

    Goto, Masao; Kanbe, Kouji; Sakai, Takanori; Inoue, Norihiro

    An experimental study of the performance of a vapour compression heat pump system using a HCFC22 and CFC114 mixture of 20, 40, 60 and 100 mass% of HCFC22 as a working fluid was carried out. Heat Transfer characteristics of the condenser and the evaporator were also investigated. The condenser and the evaporator were counter flow heat exchangers with a smooth copper tube of 12 mmID and 8 m length. The experiments were performed under the conditions that the flow rates of the heat source and sink water and their inlet temperatures of the heat exchangers were kept constant, maintaining the constant evaporating temperature at the inlet of the evaporater. The results indicate that the coefficients of performance (COP) in case of the mixtures are about 45% higher than that of pure HCFC22 in the range of CFC1l4 mass fraction from 0.6 to 0.8 and the effect of the composition of mixtures on COP is well agreement with that obtained from the thermodynamic cycle analysis. Overall heat transfer coefficient of mixtures decreases with increasing CFC114 mass fraction of the mixture and the empirical correlation for the effect of the composion of the mixture on condensation heat transfer is obtained.

  6. Effect of ZnO nanoparticles in R290/R600a (50/50) based vapour compression refrigeration system added via lubricant oil on compressor suction and discharge characteristics

    Science.gov (United States)

    Kumar, Ravinder; Singh, Jagdev

    2017-05-01

    The primary source of energy consumption in a vapour compression refrigeration system is a compressor. The possibility of a reduction in the work of compression may leads to enhance the compressor suction and discharge characteristics and the overall performance of the refrigeration system. The present experimental investigation based upon the study of ZnO nanoparticles in a vapour compression refrigeration system using hydrocarbon blend R290/R600a (50/50) as a refrigerant. The zinc oxide nanoparticles are appended with system refrigerant via compressor lubricating oil. The results observed that by using different weight concentrations of nanoparticles in R290/R600a refrigeration system, both the compressor suction and discharge pressures and temperatures were reduced compared to conventional system. The viscosity of mineral oil with the addition of nanoparticles increases. The compressor energy consumption was reduced by 7.48 % using (0.2-1.0) wt% concentrations of nanoparticles. The COP of the refrigeration system has been increased by about 46 % with the addition of nanoparticles. Thus, the ZnO nanoparticles worked efficiently in the R290/R600a refrigeration system.

  7. Theoretical investigations on simultaneous operation of vapour compression refrigeration cycle and Stirling cycle in miniature Stirling cooler with two-component two-phase mixture

    Science.gov (United States)

    Bapat, S. L.

    2000-01-01

    The cyclic analysis of Stirling cycle working with a single gaseous fluid is modified to suit two-component two-phase mixtures. When the results were examined carefully, these showed that a substantial increase in cooling effect is obtained. In order to understand how the two-component two-phase working fluid functions in the Stirling cooler, some other processes, generally not coming into picture with a single gaseous fluid, are also considered to get good idea about the working of the cooler and then the estimates about the performance of the cooler are obtained. The processes include, simultaneous compression of gases with different ratios of Cp and Cv, the drop-wise condensation, isentropic expansion of liquid in presence of other gas, the entrainment process as observed in heat pipes, and saturation process as observed in air humidification process. The change in regenerator effectiveness due to condensation in the regenerator also has to be considered. How the above mentioned processes are affecting the system performance is discussed in detail. The analysis shows that the Stirling cycle and vapour compression cycle with isentropic expansion operate simultaneously. The criterion for selection of the gaseous carrier fluid and the condensable fluid, which undergoes phase change is established. For selection of carrier gas, helium and hydrogen are considered and for the condensable fluid, nitrogen, carbon mono-oxide, nitrogen-tri-fluoride and neon are compared. Using the above mentioned criterion, helium and nitrogen combination has been chosen for cold tip temperatures in liquid nitrogen temperature range. The paper discusses the analytical approach and the results indicate that the presence of vapour compression cycle with isentropic expansion, operating under a small difference between the condensation and evaporation temperatures, leads to high values of cooling effect and coefficient of performance (COP). It also shows that beyond a certain concentration

  8. Thermodynamic simulation for a vapour compression system using organic refrigerants; Simulacao termodinamica do ciclo de compressao a vapor utilizando fluidos refrigerantes organicos

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Francisco S.; Santos, Carlos A.C. dos [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Lab. de Energia Solar; Torres, Ednildo A.; Jesus, Marcos F. de [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Dept. de Engenharia Quimica. Lab. de Energia e Gas

    2004-07-01

    According to the Montreal protocol, it is foreseen a total retreat of CFCs and HCFCs in applications of refrigeration and air conditioning. Before this context, considerable attention has been used in the substitution of HCFC-22 (R22) in systems of air conditioning, where they appear as possible alternatives two HFCs (R407c and R410a) and two HCs (R290 and R600a). In this work, possibilities and problems for the use of these fluids as alternatives to R22 in equipment of refrigeration are discussed. Five refrigerants (R22, R407c, R410a, R290 and R600) are selected, computational simulations done and your characteristic in terms of thermodynamic cycles are shown. The obtained conclusion is that propane offers the best alternative for R22 in equipment of refrigeration, because this besides being energetically efficient, is environmentally acceptable. However, safety precautions due to your inflammability must be seriously taken into account. For some applications the substitution of the current fluids (halocarbons) by the hydrocarbons can be done without larger additional costs, but not in the general case. (author)

  9. Distillation with Vapour Compression. An Undergraduate Experimental Facility.

    Science.gov (United States)

    Pritchard, Colin

    1986-01-01

    Discusses the need to design distillation columns that are more energy efficient. Describes a "design and build" project completed by two college students aimed at demonstrating the principles of vapour compression distillation in a more energy efficient way. General design specifications are given, along with suggestions for teaching…

  10. New Regenerative Cycle for Vapor Compression Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Mark J. Bergander

    2005-08-29

    second step of compression. In the proposed system, the compressor compresses the vapor only to 50-60% of the final pressure, while the additional compression is provided by a jet device using internal potential energy of the working fluid flow. Therefore, the amount of mechanical energy required by a compressor is significantly reduced, resulting in the increase of efficiency (either COP or EER). The novelty of the cycle is in the equipment and in the way the multi-staging is accomplished. The anticipated result will be a new refrigeration system that requires less energy to accomplish a cooling task. The application of this technology will be for more efficient designs of: (1) Industrial chillers, (2) Refrigeration plants, (3) Heat pumps, (4) Gas Liquefaction plants, (5) Cryogenic systems.

  11. Numerical approach to solar ejector-compression refrigeration system

    Directory of Open Access Journals (Sweden)

    Zheng Hui-Fan

    2016-01-01

    Full Text Available A model was established for solar ejector-compression refrigeration system. The influence of generator temperature, middle-temperature, and evaporator temperature on the performance of the refrigerant system was analyzed. An optimal generator temperature is found for maximal energy efficiency ratio and minimal power consumption.

  12. Performance evaluation of a solar ejector-vapour compression cycle for cooling application

    Science.gov (United States)

    Megdouli, K.; Elakhdar, M.; Nahdi, E.; Kairouani, L.; Mhimid, A.

    2015-04-01

    This study deals with the performance of the ejector-vapour compression cycle assisted by solar. The effect of operating conditions on the combined cycle performance is examined. Also, a comparison of the system performance with environment friendly refrigerants (R134a, R600, R123, R141b, R142b, R152a, R290, and R245fa) is made. This performance is calculated using an empirical correlation. Thermodynamic properties of functioning fluids are obtained with package REFPROP 8. Using the typical meteorological year file containing the weather data of the city of Tunis, the system performance is computed for three collector types. The theoretical results show that the R290 offers the highest coefficient of performance, COP=3.75, for generator temperature TB = 78°C, condenser temperature Tc = 30°C and the intercooler temperature Te = 15°C.

  13. COMPARISON OF ENERGY AND EXERGY EFFICIENCIES OF ABSORPTION REFRIGERATION SYSTEM WITH MECHANICAL COMPRESSION REFRIGERATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Gülay YAKAR

    2005-02-01

    Full Text Available In this study, energy and exergy analysis of absorption refrigeration system using LiBr- water and mechanical compression refrigeration system using R134-a were performed at different evaporation temperatures. The results are presented in tables and figures.

  14. Vapour and air bubble collapse analysis in viscous compressible water

    Directory of Open Access Journals (Sweden)

    Gil Bazanini

    2001-01-01

    Full Text Available Numerical simulations of the collapse of bubbles (or cavities are shown, using the finite difference method, taking into account the compressibility of the liquid, expected to occur in the final stages of the collapse process. Results are compared with experimental and theoretical data for incompressible liquids, to see the influence of the compressibility of the water in the bubble collapse. Pressure fields values are calculated in an area of 800 x 800 mm, for the case of one bubble under the hypothesis of spherical symmetry. Results are shown as radius versus time curves for the collapse (to compare collapse times, and pressure curves in the plane, for pressure fields. Such calculations are new because of their general point of view, since the existing works do not take into account the existence of vapour in the bubble, neither show the pressure fields seen here. It is also expected to see the influence of the compressibility of the water in the collapse time, and in the pressure field, when comparing pressure values.

  15. Effect of evaporator temperature on vapor compression refrigeration system

    Directory of Open Access Journals (Sweden)

    Abdullah A.A.A. Al-Rashed

    2011-12-01

    Full Text Available This paper presents a comparable evaluation of R600a (isobutane, R290 (propane, R134a, R22, for R410A, and R32 an optimized finned-tube evaporator, and analyzes the evaporator effect on the system coefficient of performance (COP. Results concerning the response of a refrigeration system simulation software to an increase in the amount of oil flowing with the refrigerant are presented. It is shown that there is optima of the apparent overheat value, for which either the exchanged heat or the refrigeration coefficient of performance (COP is maximized: consequently, it is not possible to optimize both the refrigeration COP and the evaporator effect. The obtained evaporator optimization results were incorporated in a conventional analysis of the vapor compression system. For a theoretical cycle analysis without accounting for evaporator effects, the COP spread for the studied refrigerants was as high as 11.7%. For cycle simulations including evaporator effects, the COP of R290 was better than that of R22 by up to 3.5%, while the remaining refrigerants performed approximately within a 2% COP band of the R22 baseline for the two condensing temperatures considered.

  16. A Case Study of a Low Powervapour Compression Refrigeration System

    Science.gov (United States)

    Abinav, R.; Nambiar, G. K.; Sahu, Debjyoti

    2016-09-01

    Reported in this paper is a case study on a normal vapor compression refrigeration system which is expected to be run by photovoltaic panels to utilize minimum grid power. A small 120 W refrigerator is fabricated out of commercially available components and run by an inverter and battery connected to solar photovoltaic panel as well as grid. Temperature at several points was measured and the performance was evaluated. The Coefficient of performance (COP) to run such refrigerator is estimated after numerical simulation of major components namely, evaporator, condenser and a capillary tube. The simulation was done to obtain an effective cooling temperature and the results were compared with measured temperatures. Calculation proves to be in conformity with the actual model.

  17. Development of Stirling cycle refrigerators as an alternative to cold-vapour refrigerators; Entwicklung von Stirling-Kaeltemaschinen alternativ zu Kaltdampf-Kaeltemaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Schikora, H.; Siegel, A.; Schiefelbein, K. [Essen Univ. (Gesamthochschule) (Germany). Inst. fuer Angewandte Thermodynamik und Klimatechnik

    1998-10-01

    For some years already, the Institut fuer Angewandte Thermodynamik und Klimatechnik has been studying Stirling cycle refrigerators using helium, a technical gas causing no environmental harm whatsoever. As calculations show, a Stirling refrigerator`s energetic performance is on a par with that of a single-stage, cold-vapour refrigerator if the heat emission temperature differs from the cold generation temperature by more than 55 K. As part of a research project sponsored by the federal ministry of science and technology which has been under way since January 1998, a Stirling refrigerator for deep-freezing at supermarkets is being developed. The results of this work are to demonstrate whether the theoretical calculations are correct and to mature, moreover, into a design not too remote from transfer to market. (orig.) [Deutsch] Das Institut fuer Angewandte Thermodynamik und Klimatechnik beschaeftigt sich seit einigen Jahren mit Stirling-Kaeltemaschinen, in denen das in jeder Beziehung umweltunschaedliche Arbeitsgas Helium eingesetzt wird. Die berechneten Leistungsdaten einer Stirling-Kaeltemaschine zeigen, dass bei Differenzen zwischen der Temperatur der Waermeabgabe und der Temperatur der Kaelteerzeugung von mehr als 55 K die Stirling-Kaeltemaschine mit einer einstufigen Kaltdampf-Kaeltemaschine in energetischer Hinsicht konkurrieren kann. Aus diesem Grund wird, in einem seit Januar 1998 laufenden BMBf-Forschungsvorhaben, eine Stirling-Kaeltemaschine fuer das Anwendungsgebiet `Tiefkuehlung in Supermaerkten` entwickelt. Die Ergebnisse dieser Entwicklungsarbeit sollen zum einen zeigen, ob die theoretischen Berechnungen richtig waren und zum anderen in einer Maschinenkonstruktion muenden, die nicht allzuweit von der Marktreife entfernt ist. (orig.)

  18. A review on the recent development of solar absorption and vapour compression based hybrid air conditioning with low temperature storage

    Directory of Open Access Journals (Sweden)

    Noor D. N.

    2016-01-01

    Full Text Available Conventional air conditioners or vapour compression systems are main contributors to energy consumption in modern buildings. There are common environmental issues emanating from vapour compression system such as greenhouse gas emission and heat wastage. These problems can be reduced by adaptation of solar energy components to vapour compression system. However, intermittence input of daily solar radiation was the main issue of solar energy system. This paper presents the recent studies on hybrid air conditioning system. In addition, the basic vapour compression system and components involved in the solar air conditioning system are discussed. Introduction of low temperature storage can be an interactive solution and improved economically which portray different modes of operating strategies. Yet, very few studies have examined on optimal operating strategies of the hybrid system. Finally, the findings of this review will help suggest optimization of solar absorption and vapour compression based hybrid air conditioning system for future work while considering both economic and environmental factors.

  19. Magnetic Refrigeration and the Magnetocaloric Effect

    DEFF Research Database (Denmark)

    Petersen, Thomas Frank; Pryds, Nini; Smith, Anders

    2006-01-01

    Magnetic refrigeration at room temperature is an emerging technology for refrigeration, which promises low energy consumption and is environmentalle friendly. Magnetic refrigeration is based on the magnetocaloric effect, which manifests itself as a reversibel increase in temperature when magnetic...... material are plased in a magnetic field. This paper introduces and describes magnetic refrigeration cycles and the magnetocaloric effect, and shows how magnetic refrigeration can be an alternative to vapour-compression refrigeration,. A review of the Danish research on magnetic refrigeration at Risø...

  20. closed cycle solar refrigeration with the calcium chloride system

    African Journals Online (AJOL)

    user

    1986-09-01

    Sep 1, 1986 ... machines. These include the vapour compression, the vapour absorption and the thermoelectric methods. Figure 1 gives an option tree of the alternative schemes. When the ... be liquid or solid, absorbs the refrigerant exothermically at low ..... Chiller, M.S. Thesis, Colorado. State University, USA (1984). 2.

  1. Parametric analysis of a combined dew point evaporative-vapour compression based air conditioning system

    Directory of Open Access Journals (Sweden)

    Shailendra Singh Chauhan

    2016-09-01

    Full Text Available A dew point evaporative-vapour compression based combined air conditioning system for providing good human comfort conditions at a low cost has been proposed in this paper. The proposed system has been parametrically analysed for a wide range of ambient temperatures and specific humidity under some reasonable assumptions. The proposed system has also been compared from the conventional vapour compression air conditioner on the basis of cooling load on the cooling coil working on 100% fresh air assumption. The saving of cooling load on the coil was found to be maximum with a value of 60.93% at 46 °C and 6 g/kg specific humidity, while it was negative for very high humidity of ambient air, which indicates that proposed system is applicable for dry and moderate humid conditions but not for very humid conditions. The system is working well with an average net monthly power saving of 192.31 kW h for hot and dry conditions and 124.38 kW h for hot and moderate humid conditions. Therefore it could be a better alternative for dry and moderate humid climate with a payback period of 7.2 years.

  2. The Prospects of Alternatives to Vapor Compression Technology for Space Cooling and Food Refrigeration Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Daryl R.; Dirks, James A.; Fernandez, Nicholas; Stout, Tyson E.

    2010-03-31

    Five alternatives to vapor compression technology were qualitatively evaluated to determine their prospects for being better than vapor compression for space cooling and food refrigeration applications. The results of the assessment are summarized in the report. Overall, thermoacoustic and magnetic technologies were judged to have the best prospects for competing with vapor compression technology, with thermotunneling, thermoelectric, and thermionic technologies trailing behind in that order.

  3. Simulation of absorption refrigeration system for automobile application

    Directory of Open Access Journals (Sweden)

    Ramanathan Anand

    2008-01-01

    Full Text Available An automotive air-conditioning system based on absorption refrigeration cycle has been simulated. This waste heat driven vapor absorption refrigeration system is one alternate to the currently used vapour compression refrigeration system for automotive air-conditioning. Performance analysis of vapor absorption refrigeration system has been done by developing a steady-state simulation model to find the limitation of the proposed system. The water-lithium bromide pair is used as a working mixture for its favorable thermodynamic and transport properties compared to the conventional refrigerants utilized in vapor compression refrigeration applications. The pump power required for the proposed vapor absorption refrigeration system was found lesser than the power required to operate the compressor used in the conventional vapor compression refrigeration system. A possible arrangement of the absorption system for automobile application is proposed.

  4. Thermodynamic Analysis of Combined Vapor Compression and Vapor Absorption Refrigeration System

    Directory of Open Access Journals (Sweden)

    AAMIR SHAIKH

    2017-07-01

    Full Text Available Two of the popular refrigeration cycles, VC (Vapor Compression, and VA (Vapor Absorption are used extensively for refrigeration purposes. In this paper, a system is proposed that works using both cycles powered by an IC (Internal Combustion engine, where mechanical energy is used to run the VC cycle while exhaust gasses are used to operate the VA cycle. The VC cycle works on R12 refrigerant while LiBr-H2O combination is selected for operation of VA cycle. Firstly, the refrigeration system is modeled, followed by a parametric study to investigate the impacts of various operating parameters on the system performance. The results exhibit that for maximum chilling and overall performance, the condenser and evaporator pressures in the VC cycle are obtained as 710 and 340 kPa, respectively, whereas generator and absorber temperatures in VA cycle are 85 and 20oC, respectively

  5. The design and development of a vapor compression refrigerator/freezer for spacelab

    Science.gov (United States)

    Hye, A.

    1983-01-01

    A computer simulation was performed to determine the design criteria for a spacelab refrigerator/freezer using the test results of a vapor compression refrigerator/freezer which flew on STS-4 without problem. It has been established to have a vapor Reynolds number over 3000 at a vapor quality of 0.2 to maintain annular boiling in the evaporator and for the condenser to have a vapor Reynolds number over 15000 at its inlet to maintain annular condensation. These two constraints will virtually eliminate the effect of gravity on the performance of the refrigerator/freezer. These results are being used to build a refrigerator/freezer which will fly in Spacelab-4 scheduled for launch in December 1985.

  6. Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

    KAUST Repository

    Thu, Kyaw

    2017-05-18

    The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

  7. Air conditioning without compression-type refrigerators; Klimatisierung ohne Kompressions-Kaeltemaschine

    Energy Technology Data Exchange (ETDEWEB)

    Reinmuth, F. [Fachhochschule Muenster, Burgsteinfurt (Germany). Fachbereich Versorgungstechnik

    1997-12-01

    The problematic refrigerants formerly used in compression-type refrigerators resulted in the development or discovery of a large number of alternatives, some of which will surely gain economic importance. The contribution outlines the current state of the art, with particular interest in the energy aspect. (orig.) [Deutsch] Die Problematik der bisher in Kompressions-Kaeltemachinen eingesetzten Kaeltemittel - die Stichworte sind Ozonloch und Treibhauseffekt - fuehrte in den letzten Jahren zur Entwicklung bzw. Neuentdeckung einer Zahl von Alternativen, von denen einige ganz zweifelsfrei grosse wirtschaftliche Bedeutung erlangen werden. Mit dem vorliegenden Aufsatz soll ein Ueberblick vermittelt und der Stand der Technik insbesondere unter energetischen Gesichtspunkten dargestellt werden. (orig.)

  8. Industrial refrigeration by absorption/compression; Refrigeracion industrial por absorcion/compresion

    Energy Technology Data Exchange (ETDEWEB)

    Ayala Delgado, Ramon; Heard, Christopher Lionel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    The use of the absorption/compression refrigeration in the industrial area is analyzed. It is estimated than in Mexico 50% of the food is wasted for lack of refrigeration in the producing centers and by the inefficient distribution system, as well as for the hot climate. The functioning of the absorption refrigeration and the hybrid system absorption/compression which can operate with the two thermodynamic cycles in variable proportions, depending on the specific application, looking for operational advantages and energy efficiency is described. This type of technology could be applied in Mexico due to the lack of industrial refrigeration and to the need of substituting compressors in some companies which have up to 20 years of use [Espanol] Se analiza el uso de la refrigeracion por absorcion/compresion en el area industrial. En Mexico se estima que se desperdicia el 50% de los alimentos por falta de refrigeracion en los centros productores y por el deficiente sistema de distribucion, asi como por el clima calido. Se describe el funcionamiento de la refrigeracion por absorcion y la refrigeracion por absorcion/compresion o sistema hibrido, el cual puede funcionar con los dos tipos de ciclos termodinamicos, en proporciones variables, dependiendo de la aplicacion especifica, buscando ventajas de operacion y eficiencia energetica. Este tipo de tecnologia podria aplicarse en Mexico debido a la falta de refrigeracion industrial y a la necesidad de sustituir compresores en algunas empresas los cuales tienen hasta 20 anos de uso

  9. First Law Analysis of a Two-stage Ejector-vapor Compression Refrigeration Cycle working with R404A

    Directory of Open Access Journals (Sweden)

    Feiza Memet

    2011-10-01

    Full Text Available The traditional two-stage vapor compression refrigeration cycle might be replaced by a two-stage ejector-vapor compression refrigeration cycle if it is aimed the decrease of irreversibility during expansion. In this respect, the expansion valve is changed with an ejector. The performance improvement is searched in the case of choosing R404A as a refrigerant. Using the ejector as an expansion device ensures a higher value for COP compared to the traditional case. On the basis of the ejector approach it possible to identify the highest COP value for a given condensation temperature, when the evaporation temperature varies.

  10. Performance Analysis of Solar Combined Ejector-Vapor Compression Cycle Using Environmental Friendly Refrigerants

    Directory of Open Access Journals (Sweden)

    A. B. Kasaeian

    2013-04-01

    Full Text Available In this study, a new model of a solar combined ejector-vapor compression refrigeration system has been considered. The system is equipped with an internal heat exchanger to enhance the performance of the cycle. The effects of working fluid and operating conditions on the system performance including COP, entrainment ratio (ω, compression ratio (rp and exergy efficiency were investigated. Some working fluids suggested are: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e and R1234ze(z. The results show that R114 and R1234ze(e yield the highest COP and exergy efficiency followed by R123, R245fa, R365mfc, R141b, R152a and R600a. It is noticed that the COP value of the new solar ejector-vapor compression refrigeration cycle is higher than that of the conventional ejector cycle with R1234ze(e for all operating conditions. This paper also demonstrates that R1234ze(e will be a suitable refrigerant in the solar combined ejector-vapor compression refrigeration system, due to its environmental friendly properties and better performance. ABSTRAK: Kajian ini menganalisa model baru sistem penyejukan mampatan gabungan ejektor-wap solar.Sistem ini dilengkapi dengan penukar haba dalaman untuk meningkatkan prestasi kitaran.Kesan bendalir bekerja dan keadaan operasi pada prestasi sistem termasuk COP, nisbah pemerangkapan (ω, nisbah mampatan (rp dan kecekapan eksergi telah disiasat.Beberapa bendalir bekerja yang dicadangkan adalah: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e dan R1234ze(z.Hasil kajian menunjukkan R114 dan R1234ze(e menghasilkan COP dan kecekapan eksergi tertinggi diikuti oleh R123, R245fa, R365mfc, R141b, R152a dan R600a.Didapati nilai COP kitaran penyejukan mampatan bagi ejektor-wap solar baru adalah lebih tinggi daripada kitaran ejektor konvensional dengan R1234ze(e bagi semua keadaan operasi.Kertas kerja ini juga menunjukkan bahawa R1234ze(e boleh menjadi penyejuk yang sesuai dalam sistem penyejukan mampatan gabungan ejektor

  11. Compressibility and specific heats of heavier condensed rare gases near the liquid-vapour critical point

    CERN Document Server

    March, N H

    2003-01-01

    Sarkisov (J. Chem. Phys. 119, 373, 2003) has recently discussed the structural behaviour of a simple fluid near the liquid-vapour critical point. His work, already compared with computer simulation studies, is here brought into direct contact for the heavier condensed rare gases Ar, Kr and Xe with (a) experiment and (b) earlier theoretical investigations. Directions for future studies then emerge.

  12. Technical and Economic Working Domains of Industrial Heat Pumps: Part 1 - Vapour Compression Heat Pumps

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Jensen, Jonas Kjær; Markussen, Wiebke Brix

    2014-01-01

    the constraints of available refrigeration equipment and a requirement of a positive Net Present Value of the investment. The considered sink outlet temperature range is from 40 °C to 140 °C, but for the heat pumps considered in this paper, the upper limit is 100 °C. Five heat pumps are studied. For each set...

  13. Advanced exergy analysis of a R744 booster refrigeration system with parallel compression

    DEFF Research Database (Denmark)

    Gullo, Paride; Elmegaard, Brian; Cortella, Giovanni

    2016-01-01

    In this paper, the advanced exergy analysis was applied to a R744 booster refrigeration system with parallel compression taking into account the design external temperatures of 25 degrees C and 35 degrees C, as well as the operating conditions of a conventional European supermarket. The global...... stage) compressor and the MT (medium temperature) display cabinet exhibited the highest enhancement potential. The further splitting of their corresponding exergy destruction rates into their different parts and the following assessment of the interactions among the components allowed figuring out...... the real achievable improvements. The avoidable irreversibilities of the HS compressor and that of the MT evaporator were mainly and completely endogenous, respectively. On the other hand, the gas cooler/condenser could be predominantly improved by decreasing the inefficiencies of the MT evaporator...

  14. Stirling-type pulse tube refrigerator (PTR) with cold compression: Cold compressor, colder expander

    Science.gov (United States)

    Park, Jiho; Ko, Junseok; Cha, Jeongmin; Jeong, Sangkwon

    2016-03-01

    This research paper focuses on the performance prediction and its validation via experimental investigation of a Stirling-type pulse tube refrigerator (PTR) equipped with a cold linear compressor. When the working gas is compressed at cryogenic temperature, the acoustic power (PV power) can be directly transmitted through the regenerator to the pulsating tube without experiencing unnecessary precooling process. The required PV power generated by the linear compressor, furthermore, can be significantly diminished due to the relatively small specific volume of the working gas at low temperature. The PTR can reach lower temperature efficiently with higher heat lift at the corresponding temperature than other typical single-stage Stirling-type PTRs. Utilizing a cryogenic reservoir as a warm end and regulating the entire operating temperature range of the PTR will enable a PTR to operate efficiently under space environment. In this research, the experimental validation as a proof of concept was carried out to demonstrate the capability of PTR operating between 80 K and 40 K. The linear compressor was submerged in a liquid nitrogen bath and the lowest temperature was measured as 38.5 K. The test results were analyzed to identify loss mechanisms with the simple numerical computation (linear model) which considers the dynamic characteristics of the cold linear compressor with thermo-hydraulic governing equations for each of sub components of the PTR. All the mass flows and pressure waves were assumed to be sinusoidal.

  15. Finite time thermodynamics of power and refrigeration cycles

    CERN Document Server

    Kaushik, Shubhash C; Kumar, Pramod

    2017-01-01

    This book addresses the concept and applications of Finite Time Thermodynamics to various thermal energy conversion systems including heat engines, heat pumps, and refrigeration and air-conditioning systems. The book is the first of its kind, presenting detailed analytical formulations for the design and optimisation of various power producing and cooling cycles including but not limited to: • Vapour power cycles • Gas power cycles • Vapour compression cycles • Vapour absorption cycles • Rankine cycle coupled refrigeration systems Further, the book addresses the thermoeconomic analysis for the optimisation of thermal cycles, an important field of study in the present age and which is characterised by multi-objective optimization regarding energy, ecology, the environment and economics. Lastly, the book provides the readers with key techniques associated with Finite Time Thermodynamics, allowing them to understand the relevance of irreversibilitie s associated with real processes and the scientific r...

  16. Internal heat exchange in an ejector-compression solar refrigeration system with R142b

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Joge I; Estrada, Claudio A; Best, Roberto [Centro de Investigacion en Energia, UNAM, Temixco, Morelos (Mexico); Dorantes Ruben, J [Departamento de Energia, UNAM Azcapotzalco, Mexico, D.F. (Mexico)

    2000-07-01

    One way to use more efficiently the actual energy transfer in the ejector-compression system, is the use of heat exchangers between some of the components. The inclusion of two heat exchangers, preheater and precooler, is considered in a basic ejector-compression refrigeration system with refrigerant 142b. This study accounts for the energy and exergy efficiencies. COP and {epsilon}, according to parameter variations such as ejector efficiency, generation temperature with different superheating, condensation temperature and heat exchangers effectiveness. As known, the most important parameters in ejector-compression system analysis are the entrain-ment ratio U and system efficiencies COP and {epsilon}. The highest system COP and {epsilon}, as the entrainment ratio U, correspond to the highest exchangers effectiveness, highest superheating generator temperatures, highest ejector efficiency and lowest condenser temperature. For the COP and {epsilon} ratios, their maxima correspond to the same independent variables aforementioned for one of the higher superheating generator temperatures. In this case, this result indicates that the exergy efficiency {epsilon} does not contradict the information given by energy efficiency COP. So, to select correctly and optimum design condition, is enough to employ the COP ratio, which maximum value for the data shown corresponds to a superheating generator temperature of about 110 Celsius degrees, that can only be reached by evacuated tubular collectors or CPC solar concentrators. [Spanish] Una forma de usar mas eficientemente la transferencia real de energia en el sistema eyector-compresion es el uso de intercambiadores de calor entre algunos de los componentes. La inclusion de dos intercambiadores de calor precalentador y pre-enfriador se considera en un sistema de refrigeracion eyector-compresion con refrigerante 142b. Este estudio toma en cuenta las eficiencias de energia y exergia, COP y {epsilon}, de acuerdo con las variaciones

  17. Compression characteristics of refrigerant-oil mixture in refrigerant compressors. 1st Report. Modeling of leakage and heat transfer; Reigai asshukuki ni okeru reibai-abura kongobutsu no asshuku tokusei. 1. More to dennetsu no model ka

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, M.; Yanagisawa, T.; Shimizu, T.; Shikata, T. [University of Shizuoka, Shizuoka (Japan). Faculty of Engineering

    1995-02-25

    Refrigeration oil is used for lubrication, sealing and cooling in refrigerant compressors, and mixing of the oil with refrigerant has great influences on compression characteristics in the compressors. In the past there were some studies in which the effect of the oil on the compressor performance was analyzed theoretically, but most of them did not discuss well the propriety of the oil treatment in the analysis. In this study, we developed the mathematical compressor model including the effect of the oil on leakage, heat transfer and flow resistance in vane compressors and examined the influence of the ways of treating the oil on the calculated results. When the model employed a quality of two-phase leakage flow equal to that in the compression chamber and a coefficient of heat transfer reflecting thermophysical properties of the oil and the refrigerant, it showed better agreement with experimental results. 18 refs., 9 figs., 1 tab.

  18. Refrigerant Charge Management and Control for Next-Generation Aircraft Vapor Compression Systems (Postprint)

    Science.gov (United States)

    2013-09-01

    found in almost every aspect of modern life, ranging from cars, homes, supermarkets , large buildings, processing plants, and computer room cooling...controllability and efficiency) can be influenced by refrigerant charge. However, questions remain regarding proper refrigerant charge to promote optimal

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-15

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

  20. Molecular-Level Computer Simulation of a Vapor-Compression Refrigeration Cycle

    Czech Academy of Sciences Publication Activity Database

    Figueroa-Gerstenmaier, S.; Francova, M.; Kowalski, M.; Lísal, Martin; Nezbeda, Ivo; Smith, W.R.

    2007-01-01

    Roč. 259, č. 2 (2007), s. 195-200 ISSN 0378-3812 R&D Projects: GA ČR(CZ) GA203/05/0725; GA AV ČR 1ET400720409; GA AV ČR 1ET400720507 Grant - others:NRCC(CA) OGP 1041 Institutional research plan: CEZ:AV0Z40720504 Source of funding: V - iné verejné zdroje Keywords : alternative refrigerants * joule-thomson expansion * adiabatic process Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.506, year: 2007

  1. Technical and economic working domains of industrial heat pumps: Part 1 - single stage vapour compression heat pumps

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Jensen, Jonas Kjær; Markussen, Wiebke Brix

    2015-01-01

    the constraints of available refrigeration equipment and a requirement of a positive net present value of the investment. Six heat pump systems were considered, corresponding to an upper limit of the sink temperature of 120 °C. For each set of heat sink and source temperatures the best available technology...... was determined. The results showed that four different heat pump systems propose the best available technology at different parts of the complete domain. Ammonia systems presented the best available technology at low sink outlet temperature. At high temperature difference between sink in- and outlet...

  2. Experimental Investigation and Flow Process Computer Simulation of the Single Mini Channel Condenser for Vapor Compression Refrigeration System

    Science.gov (United States)

    Pabilona, L. L.; Villanueva, E. P.

    2015-09-01

    This study is a computer simulation of the temperature profiles and experimental investigation of three 100 mm x 50 mm x 18 mm single mini channel condensers with hydraulic diameters of 3 mm, 2 mm, and 1mm. The mini channels which were made of copper were designed, fabricated and tested. Each unit was connected in a vapor compression cycle with R-134a as the refrigerant. The average refrigerant mass flow rates were varied from 1.296 - 69.471 g/s, and the average inlet and outlet condenser pressure variations were 102.5 - 121.8 kPa and 101.74 -121.23 kPa, respectively. Each condenser was placed inside a mini wind tunnel system where forced draft air was introduced to initiate convective heat transfer. Each condenser was tested and data were gathered every five minute interval for one hour using a Lab View Software. Computer simulations on the flow process were conducted using Solid Works software. The experimental results presented the inlet and outlet condenser pressures, and pressure drops. The experimental heat transfer coefficients were calculated at different mass fluxes during condensation. The values ranged from 3900 to 5200 W/m2-°K for the 3 mm, 2600 to 9000 W/m2-°K for the 2 mm, and 13 to 98 W/m2-°K for the 1 mm. The heat transfer coefficients calculated from experiments were then compared with the computed values using the correlations developed by Dittus-Boelter and Lee-Son. The results showed increasing deviation as the diameter decreased. The discrepancies could be attributed to the appropriateness of the Dittus-Boelter and Lee-Son correlations in small diameter channels, complexities in the flow process which involved two phase flow heat transfer in very small tubes, and the difficulties in attaining very accurate measurements in small channels.

  3. Thermodynamic, Environmental and Economic Analyses of Solar Ejector Refrigeration System Application for Cold Storage

    Directory of Open Access Journals (Sweden)

    İbrahim ÜÇGÜL

    2009-02-01

    Full Text Available The refrigeration processes have been widely applied for especially in cold storages. In these plants, the systems working with compressed vapour cooling cycles have been used as a classical method. In general, electrical energy is used for compressing in these processes. Although, mainly the electricity itself has no pollution effect on the environment, the fossil fuels that are widely used to produce electricity in the most of the world, affect the nature terribly. In short, these refrigeration plants, because of the source of the electricity pollute the nature indirectly. However, for compression an ejector refrigeration system requires one of the important renewable energy sources with negligible pollution impact on the environment, namely solar energy from a thermal source. Thermodynamical, environmental and economical aspects of the ejector refrigeration system working with solar energy was investigated in this study. As a pilot case, apple cold storage plants widely used in ISPARTA city, which 1/5 th of apple production of TURKEY has been provided from, was chosen. Enviromental and economical advantages of solar ejector refrigeration system application for cold storage dictated by thermodynamic, economic and enviromental analyses in this research.

  4. Guidelines for design and operation of compression heat pump, air conditioning and refrigerating systems with natural working fluids. Final report from Annex 22 of the IEA Heat Pump Programme

    Energy Technology Data Exchange (ETDEWEB)

    Stene, J. [SINTEF Energy Research, Trondheim (Norway)

    1998-12-01

    design and operation of energy efficient and low charge systems are also presented. Finally, various types of ammonia and hydrocarbon heat pumping systems are displayed in order to demonstrate the maturity of the technology. The latter includes, among other things, a number of indirect refrigerating systems using brines, binary ice or carbon dioxide as secondary fluids Section 6, `Carbon Dioxide as a Working Fluid`, presents the use of carbon dioxide as a working fluid in heat pumping systems. Important physical and thermophysical properties of CO2 are discussed, focusing on environmental aspects, the transcritical vapour compression process, dimensions of main components and pipelines, system energy efficiency, and safety aspects. The technological status with regard to compressors and heat exchangers is also briefly described. A number of promising heat pumping applications are pointed out in order to demonstrate the potential of the CO2 technology. Section 7, `Indirect Heat Pumping Systems`, raises important issues regarding the design and application of indirect (dual loop) heat pumping systems. A number of single-phase and phase-changing heat transfer fluids, so-called secondary fluids, secondary refrigerants or coolants, are presented with regard to thermophysical properties and other important parameters. On the application, side focus is placed on refrigerating systems in supermarkets (commercial refrigeration)

  5. A Theoretical investigation on HC Mixtures as Possible Alternatives to R134a in Vapor Compression Refrigeration

    Directory of Open Access Journals (Sweden)

    Feiza Memet

    2014-07-01

    Full Text Available This paper provides a theoretical comparison of the performance of refrigerants in use in a vapor comparison cycle. It is about the phase-out of R134a from actual refrigeration system, comparison being performed for this chemical and two more ecological mixtures: R290/R600a described as (30/70 and (40/60. Were investigated effects of condensation temperatures and evaporation temperatures on performance measures as COP (Coefficient of Performance and VCC (volumetric cooling capacity. COP is a measure of the performance of the refrigeration cycle, while VCC is an indicator of compressor size. Results of this study will reveal that R290/R600a (30/70 is a good option when it is about substitution of R134a, from energy efficiency point of view, in terms of COP. R290/R600a (40/60 has VCC values bellow the ones of R134a, but comparable.

  6. ACTIVATED CARBON/REFRIGERANT COMBINATIONS FOR ...

    African Journals Online (AJOL)

    ES Obe

    No. 1, March, 2001. 53. ACTIVATED CARBON/REFRIGERANT COMBINATIONS. FOR SOLAR REFRIGERATION APPLICATION. By. E.E. ANYANWU. 1. AND N.V. .... may be assumed that the perfect gas law is obeyed approximately by the vapour. Thus,. (2). Hence by integrating,. This linear relationship between log P and.

  7. Simulation of the performance characteristics of shell-and-tube evaporators and whole refrigeration systems; Simulation des Leistungsverhaltens von Rohrbuendelverdampfern und gesamten Kaelteanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Ciconkov, R. [Univ. ' Sv. Kiril and Metodij' , Skopje (Macedonia (The Former Yugoslav Republic of)). Masinski Fakultet; Hilligweg, A. [Georg-Simon-Ohm-Fachhochschule, Nuernberg (Germany). Fachbereich Maschinenbau und Versorgungstechnik

    2003-04-01

    The evaporator is one of the main components of a single stage vapour compression refrigeration system. Its performance characteristics has influence on the other components: Compressor, condenser and expansion device. Due to the interaction between the components the refrigeration plant has to be treated as a whole. (orig.) [German] Der Verdampfer ist eine Hauptkomponente einer einstufigen Kaltdampfkaeltemaschine. Seine Leistungscharakteristik hat Einfluss auf die anderen Komponenten: Verdichter, Verfluessiger und Expansionseinrichtung. Aufgrund der Wechselwirkungen zwischen diesen Komponenten muss eine Kaelteanlage immer in ihrer Gesamtheit betrachtet werden. (orig.)

  8. Mountain Plains Learning Experience Guide: Heating, Refrigeration, & Air Conditioning.

    Science.gov (United States)

    Carey, John

    This Heating, Refrigeration, and Air Conditioning course is comprised of eleven individualized units: (1) Refrigeration Tools, Materials, and Refrigerant; (2) Basic Heating and Air Conditioning; (3) Sealed System Repairs; (4) Basic Refrigeration Systems; (5) Compression Systems and Compressors; (6) Refrigeration Controls; (7) Electric Circuit…

  9. Computational model for refrigerators based on Peltier effect application

    Energy Technology Data Exchange (ETDEWEB)

    Astrain, D.; Vian, J.G.; Albizua, J. [Departamento de Ingenieria Mecanica, Energetica y de Materiales, Universidad Publica de Navarra, UPNa. Pamplona (Spain)

    2005-12-01

    A computational model, which simulates thermal and electric performance of thermoelectric refrigerators, has been developed. This model solves the non-linear system that is made up of the thermoelectric equations and the heat conduction equations providing values for temperature, electric consumption, heat flow and coefficient of performance of the refrigerator. Finite differences method is used in order to solve the system and also semi empirical expressions for convection coefficients. Subsequently a thermoelectric refrigerator with an inner volume of 55x10{sup -3}m{sup 3} has been designed and tested, whose cold system is composed of a Peltier pellet (50W of maximum power) and a fan of 2W. An experimental analysis of its performance in different conditions has been carried out with this prototype, which, in his turn, has been useful for assessing the accuracy of the developed model. The built thermoelectric refrigerator prototype, offers advantages with respect to vapour compression classical technology such as: a more ecological system, more silent and robust and more precise in the control of temperatures which make it suitable for camping vehicles, buses, special transports for electro medicine, etc. (author)

  10. Experimental and numerical study of two-phase flows at the inlet of evaporators in vapour compression cycles; Etude experimentale et numerique d'ecoulements diphasiques a l'entree des evaporateurs de cycles thermodynamiques

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M

    2007-09-15

    Maldistribution of liquid-vapour two phase flows causes a significant decrease of the thermal and hydraulic performance of evaporators in thermodynamic vapour compression cycles. A first experimental installation was used to visualize the two phase flow evolution between the expansion valve and the evaporator inlet. A second experimental set-up simulating a compact heat exchanger has been designed to identify the functional and geometrical parameters creating the best distribution of the two phases in the different channels. An analysis and a comprehension of the relation between the geometrical and functional parameters with the flow pattern inside the header and the two phase distribution, has been established. A numerical simulations of a stratified flow and a stratified jet flow have been carried out using two CFD codes: FLUENT and NEPTUNE. In the case of a fragmented jet configuration, a global definition of the interfacial area concentration for a separated phases and dispersed phases flow has been established and a model calculating the fragmented mass fraction has been developed. (author)

  11. Electrocaloric refrigeration: an innovative, emerging, eco-friendly refrigeration technique

    Science.gov (United States)

    Aprea, C.; Greco, A.; Maiorino, A.; Masselli, C.

    2017-01-01

    Nowadays, the refrigeration is responsible of about 15% of the overall energy consumption all over the world. Actually most of the refrigerant fluids working in vapor compression plants (VCPs) are environmentally harmful, since they presents high GWP (Global Warming Potential), which leads to a substantial warming of both earth surface and atmosphere. Electrocaloric refrigeration (ER) is an innovative, emerging refrigeration technique based on solid state refrigerant that shows a great potential. It fits in the context of environment-friendly refrigeration systems, whom are spreading increasingly to replace VCPs. ER is founded on electrocaloric effect that is a physical phenomenon found in materials with dielectric properties, electrocaloric materials. The thermodynamical cycle that best is addressed to the electrocaloric refrigeration is Active Electrocaloric Regeneration cycle (AER) that consists of two adiabatic and two isofield stages. The core of an electrocaloric refrigerator is the regenerator whom operates both as refrigerant and regenerator in an AER cycle. In this paper, we compare the energetic performance of a commercial R134a refrigeration plant to that of an electrocaloric refrigerator working with an AER cycle. The comparison is performed in term of TEWI index (Total Equivalent Warming Impact) that includes both direct and indirect contributions to global warming.

  12. 46 CFR 151.40-11 - Refrigeration systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Refrigeration systems. 151.40-11 Section 151.40-11... Refrigeration systems. (a) Boiloff systems. The venting of cargo boiloff to atmosphere shall not be used as a...) Vapor compression, tank refrigeration, and secondary refrigeration systems: The required cooling...

  13. Market analysis of mechanical vapour compression systems for the drying/evaporation of wet sludges; Marktanalyse mechanische dampcompressie systemen ten behoeve van droging/verdamping van natte slibben

    Energy Technology Data Exchange (ETDEWEB)

    Slagter, J.; Hinfelaar, J. [Tauw Milieu, Deventer (Netherlands); Ottens, E. [Econdry, Emmen (Netherlands)

    1996-03-01

    For a number of different industrial sectors in the Netherlands the possibilities for the use of the mechanical vapor compression technique to dry sludges are outlined and compared. The sectors for which the possibilities are evaluated are slaughterhouses and the meat industry, vegetables and fruit processing industry, the printing and graphics industry, and the textiles and carpets industry. Also a small number of businesses in the paper, dairy, and potato processing industry was involved. Several sludge processing techniques are compared (dewatering, mechanical vapor compression, and the final processing). In this report a brief overview is given of the results of the study. Detailed operational data were presented in classified appendices. 6 figs., 5 tabs., 3 refs.

  14. Thermoacoustic refrigeration

    Science.gov (United States)

    Garrett, Steven L.; Hofler, Thomas J.

    1991-12-01

    A new refrigerator which uses resonant high amplitude sound in inert gases to pump heat is described and demonstrated. The phasing of the thermoacoustic cycle is provided by thermal conduction. This 'natural' phasing allows the entire refrigerator to operate with only one moving part (the loudspeaker diaphragm). The thermoacoustic refrigerator has no sliding seals, requires no lubrication, uses only low-tolerance machine parts, and contains no expensive components. Because the compressor moving mass is typically small and the oscillation frequency is high, the small amount of vibration is very easily isolated. This low vibration and lack of sliding seals makes thermoacoustic refrigeration an excellent candidate for food refrigeration and commercial/residential air conditioning applications. The design, fabrication, and performance of the first practical, autonomous thermoacoustic refrigerator, which will be flown on the Space Shuttle (STS-42), are described, and designs for terrestrial applications are presented.

  15. Two-phase Flow Ejector as Water Refrigerant by Using Waste Heat

    Science.gov (United States)

    Yamanaka, H.; Nakagawa, M.

    2013-04-01

    Energy saving and the use of clean energy sources have recently become significant issues. It is expected that clean energy sources such as solar panels and fuel cells will be installed in many private dwellings. However, when electrical power is generated, exhaust heat is simultaneously produced. Especially for the summer season, the development of refrigeration systems that can use this waste heat is highly desirable. One approach is an ejector that can reduce the mechanical compression work required in a normal refrigeration cycle. We focus on the use of water as a refrigerant, since this can be safely implemented in private dwellings. Although the energy conversion efficiency is low, it is promising because it can use heat that would otherwise be discarded. However, a steam ejector refrigeration cycle requires a large amount of energy to change saturated water into vapour. Thus, we propose a more efficient two-phase flow ejector cycle. Experiments were carried out in which the quality of the two-phase flow from a tank was varied, and the efficiency of the ejector and nozzle was determined. The results show that a vacuum state can be achieved and suction exerted with a two-phase flow state at the ejector nozzle inlet.

  16. Solar Powered Refrigeration System

    Science.gov (United States)

    Ewert, Michael K. (Inventor); Bergeron, David J., III (Inventor)

    2002-01-01

    A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

  17. The Liquid Vapour Interface

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1985-01-01

    In this short review we are concerned with the density variation across the liquid-vapour interface, i.e. from the bulk density of the liquid to the essentially zero density of the vapour phase. This density variation can in principle be determined from the deviation of the reflectivity from...

  18. Modelling refrigerant distribution in minichannel evaporators

    DEFF Research Database (Denmark)

    Brix, Wiebke

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

  19. Flammable refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Gerwen, R.J.M. van; Verwoerd, M.; Oostendorp, P.A. [Netherlands Organization for Applied Scientific Research TNO, Apeldoorn (Netherlands). Dept. of Refrigeration and Heat Pump Technology

    1999-07-01

    Hydrocarbons are promising alternatives for CFC, HCFC and HFC refrigerants. Due to their flammable nature, safety aspects have to be considered carefully. The world-wide situation concerning acceptability and practical application of flammable refrigerants is becoming more and more complex and confusing. Quantification of the risks of using flammable refrigerants in specific applications is the only way to make the situation clear and to discuss this topic on the basis of facts and figures. Several Quantitative Risk Assessments (QRA) have been carried out by TNO, resulting in risk figures to be compared with generally accepted risk criteria. In addition, risk reducing measures may be evaluated by using the same kind of QRA's. The example QRA's carried out for the cooling system of a bulk milk tank and for a residential heat pump, show acceptable risk levels, as long as the proper safety measures are applied. Other QRA's for several applications (domestic refrigerators, air dehumidifiers, automotive air-conditioning etc.) containing up to a few kilograms of hydrocarbon refrigerant confirm these results. Several national, European and international (draft) standards and guidelines are available, almost always being inconsistent or conflicting. Most of them are based on refrigeration expertise and experience, and not on a quantification of the risks. A Working Group of CEN/TC 182 currently identifies and quantifies the risks of flammable refrigerants, creating a solid basis for a revision of the European safety standard for refrigerating systems and heat pumps. (orig.)

  20. Solar Absorption Refrigeration System for Air-Conditioning of a Classroom Building in Northern India

    Science.gov (United States)

    Agrawal, Tanmay; Varun; Kumar, Anoop

    2015-10-01

    Air-conditioning is a basic tool to provide human thermal comfort in a building space. The primary aim of the present work is to design an air-conditioning system based on vapour absorption cycle that utilizes a renewable energy source for its operation. The building under consideration is a classroom of dimensions 18.5 m × 13 m × 4.5 m located in Hamirpur district of Himachal Pradesh in India. For this purpose, cooling load of the building was calculated first by using cooling load temperature difference method to estimate cooling capacity of the air-conditioning system. Coefficient of performance of the refrigeration system was computed for various values of strong and weak solution concentration. In this work, a solar collector is also designed to provide required amount of heat energy by the absorption system. This heat energy is taken from solar energy which makes this system eco-friendly and sustainable. A computer program was written in MATLAB to calculate the design parameters. Results were obtained for various values of solution concentrations throughout the year. Cost analysis has also been carried out to compare absorption refrigeration system with conventional vapour compression cycle based air-conditioners.

  1. Status of not-in-kind refrigeration technologies for household space conditioning, water heating and food refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, Pradeep [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vineyard, Edward Allan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2012-07-19

    This paper presents a review of the next generation not-in-kind technologies to replace conventional vapor compression refrigeration technology for household applications. Such technologies are sought to provide energy savings or other environmental benefits for space conditioning, water heating and refrigeration for domestic use. These alternative technologies include: thermoacoustic refrigeration, thermoelectric refrigeration, thermotunneling, magnetic refrigeration, Stirling cycle refrigeration, pulse tube refrigeration, Malone cycle refrigeration, absorption refrigeration, adsorption refrigeration, and compressor driven metal hydride heat pumps. Furthermore, heat pump water heating and integrated heat pump systems are also discussed due to their significant energy saving potential for water heating and space conditioning in households. The paper provides a snapshot of the future R&D needs for each of the technologies along with the associated barriers. Both thermoelectric and magnetic technologies look relatively attractive due to recent developments in the materials and prototypes being manufactured.

  2. Commercial Refrigeration: Heat Transfer Optimization and Energy Reduction, Measurement and Verification of a Liquid Refrigerant Pump System Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gaul, Chris [National Renewable Energy Lab. (NREL), Golden, CO (United States); Sheppy, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-03-22

    This study describes the test results of a Refrigerant Pump System integrated into a commercial supermarket direct expansion (DX) vapor compression refrigeration system. The Liquid Refrigerant Pump System retrofit (patent-pending; application number 13/964,198) was introduced to NREL in August 2014 by CTA Architects Engineers.

  3. Investigations in terms of energy economy for determining the usefulness of sorption and compression refrigerating technology. T. A: Expert report. Final report; Energiewirtschaftliche Untersuchungen zur Abgrenzung der Sinnfaelligkeit von Sorptions- und Kompressionskaeltetechnik. T. A: Fachbericht. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Sager, J.

    2001-09-30

    In the frame of the study 'Investigations in terms of energy economy for determining the usefulness of sorption and compression refrigerating technology' a comparison was made between thermal cold generation by means of one-phase absorption refrigerating machines and electro-mechanical cold generation. The comparison was based upon ideal and real processes, which also included the provision of thermal energy by means of combined-cycle generation or the provision of electric energy reconnected in compensation power plants. Absorption cold generation including the use of thermal energy from a combined-cycle generation process is termed combined-cycle generation. Due to the general character of the comparison the results can also be transferred to other processes of thermal cold generation. (orig.) [German] Im Rahmen der Studie 'Energiewirtschaftliche Untersuchungen zur Abgrenzung der Sinnfaelligkeit von Sorptions- und Kompressionskaeltetechnik' wurde ein Vergleich der thermischen Kaelteerzeugung anhand einstufiger Absorptionskaeltemaschinen mit der elektro-mechanischen Kaelteerzeugung unter Zugrundelegung idealer und realer Prozesse angestellt, in den auch die Bereitstellung der thermischen Energie in Kraft-Waerme-Kopplung bzw. der elektrichen Energie umgekoppelt in Kondensationskraftwerken einbezogen wurde. Die Absorptionskaelteerzeugung unter Verwendung thermischer Energie aus einem KWK-Prozess wird mit Kraft-Waerme-Kopplung bezeichnet. Aufgrund des allgemeingueltigen Charakters des Vergleichs sind die Ergebnisse auch auf andere Verfahren der thermischen Kaelteerzeugung uebertragbar. (orig.)

  4. Feasibility of waste heat recovery concepts for geothermal refrigeration and air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R.

    1986-01-01

    This paper presents the qualitative feasibility of two waste heat recovery concepts for geothermal refrigeration and air conditioning. The high temperature available at shallow depths of abandoned or dry wells in oil fields and the natural gas which is being flared without any use near oil producing wells, can be used as heat input for vapour absorption cooling systems. Depending upon the quantity and quality of low grade heat from these sources, conventional refrigerant-absorbent combinations, e.g. water-lithium bromide and ammonia-water may be used for refrigeration and air conditioning purposes in the basic vapour absorption systems.

  5. Compressor Properties in Sucking Two Phase Refrigerant

    Science.gov (United States)

    Inoue, Seiji; Nakayama, Masahiro; Matsuoka, Fumio

    A simulation model is proposed to analyze refrigerant properties in suction,compression and discharge process in rotary compressors,and compressor performance is analyzed by the calculations and the experiments in this paper. Heat transfer coefficients between the cylinder and refrigerant both in sucking two phase and superheated gas refrigerant have been evaluated by the calculations performed under the condition of the experiments since the validity of the simulation model has been proved by the agreement of the calculation results with the experimental ones. Linear relationship of discharge and cylinder temperature to compressor frequency and suction quality has been clarified by the experimental results. Mechanisms of the compressor performance have also analyzed by the refrigerant properties in the compression mechanism calculated every angle of the rolling piston in detail.

  6. Refrigeration and Food Safety

    Science.gov (United States)

    ... Forms Standard Forms FSIS United States Department of Agriculture Food Safety and Inspection Service About FSIS District ... 286) Actions ${title} Loading... Refrigeration and Food Safety History of Refrigeration Importance of Refrigeration Types of Bacteria ...

  7. Solar-Powered Refrigeration System

    Science.gov (United States)

    Ewert, Michael K. (Inventor); Bergeron, David J., III (Inventor)

    2001-01-01

    A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure. and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

  8. Solar-Powered Refrigeration System

    Science.gov (United States)

    Ewert, Michael K. (Inventor); Bergeron, David J., III (Inventor)

    2002-01-01

    A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

  9. Two-phase flow in refrigeration systems

    CERN Document Server

    Gu, Junjie; Gan, Zhongxue

    2013-01-01

    Two-Phase Flow in Refrigeration Systems presents recent developments from the authors' extensive research programs on two-phase flow in refrigeration systems. This book covers advanced mass and heat transfer and vapor compression refrigeration systems and shows how the performance of an automotive air-conditioning system is affected through results obtained experimentally and theoretically, specifically with consideration of two-phase flow and oil concentration. The book is ideal for university postgraduate students as a textbook, researchers and professors as an academic reference book, and b

  10. Effect of Liquid/Vapour Maldistribution on the Performance of Plate Heat Exchanger Evaporators

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Kærn, Martin Ryhl; Ommen, Torben Schmidt

    2015-01-01

    Plate heat exchangers are often applied as evaporators in industrial refrigeration and heat pump systems. In the design and modelling of such heat exchangers the flow and liquid/vapour distribution is often assumed to be ideal. However, maldistribution may occur and will cause each channel...... to behave differently due to the variation of the mass flux and vapour quality. To evaluate the effect of maldistribution on the performance of plate heat exchangers, a numerical model is developed in which the mass, momentum and energy balances are applied individually to each channel, including suitable...... correlations for heat transfer and pressure drop. The flow distribution on both the refrigerant and secondary side is determined based on equal pressure drop while the liquid/vapour distribution is imposed to the model. Results show that maldistribution may cause up to a 25 % reduction of the overall heat...

  11. Heat pump employing optimal refrigerant compressor for low pressure ratio applications

    Science.gov (United States)

    Ecker, Amir L.

    1982-01-01

    What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler for circulating the fluid in heat exchange relationship with a refrigerant fluid; two refrigerant heat exchangers; one for effecting the heat exchange with the fluid and a second refrigerant-heat exchange fluid heat exchanger for effecting a low pressure ratio of compression of the refrigerant; a rotary compressor for compressing the refrigerant with low power consumption at the low pressure ratio; at least one throttling valve connecting at the inlet side of heat exchanger in which liquid refrigerant is vaporized; a refrigerant circuit serially connecting the above elements; refrigerant in the circuit; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant.

  12. Prediction of thermodynamic properties of refrigerants using data mining

    Energy Technology Data Exchange (ETDEWEB)

    Kuecueksille, Ecir Ugur, E-mail: ecir@tef.sdu.edu.t [Department of Mechanical Education, Technical Education Faculty, Sueleyman Demirel University, 32260 Isparta (Turkey); Selbas, Resat, E-mail: selbas@tef.sdu.edu.t [Department of Mechanical Education, Technical Education Faculty, Sueleyman Demirel University, 32260 Isparta (Turkey); Sencan, Arzu, E-mail: sencan@tef.sdu.edu.t [Department of Mechanical Education, Technical Education Faculty, Sueleyman Demirel University, 32260 Isparta (Turkey)

    2011-02-15

    The analysis of vapor compression refrigeration systems requires the availability of simple and efficient mathematical formulations for the determination of thermodynamic properties of refrigerants. The aim of this study is to determine thermodynamic properties as enthalpy, entropy and specific volume of alternative refrigerants using data mining method. Alternative refrigerants used in the study are R134a, R404a, R407c and R410a. The results obtained from data mining have been compared to actual data from the literature. The study shows that the data mining methodology is successfully applicable to determine enthalpy, entropy and specific volume values for any temperature and pressure of refrigerants. Therefore, computation time reduces and simulation of vapor compression refrigeration systems is fairly facilitated.

  13. Refrigeration generation using expander-generator units

    Science.gov (United States)

    Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

    2016-05-01

    The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

  14. Feasibility and design studies for heat recovery from a refrigeration system with a Canopus heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, S.C.; Singh, M. [Indian Inst. of Tech., New Delhi (India). Centre of Energy Studies

    1995-10-01

    This paper presents an investigation of the feasibility of heat recovery from the condenser of a vapour compression refrigeration (VCR) system through a Canopus heat exchanger (CHE) between the compressor and condenser components. The presence of the CHE makes it possible to recover the superheat of the discharged vapour and utilize it for increasing the temperature of the external fluid (water) removing heat from the condenser. The effects of the operating temperatures in the condenser and evaporator for different inlet water temperatures and mass flow rates on the heat recovery output and its distribution over the condenser and CHE (the fraction of the condenser heat available through the CHE), available outlet water temperature and heat recovery factor have all been studied and optimum operating parameters for feasible heat recovery have been ascertained. The parametric results obtained for different working fluids, such as R-22, R-12, R-717 and R-500, have been presented. It is found that, in general, a heat recovery factor of the order of 2.0 and 40% of condenser heat can be recovered through the Canopus heat exchanger for a typical set of operating conditions. (Author)

  15. The maximum cooling density of a realistic Stirling refrigerator

    Science.gov (United States)

    Berrin Erbay, L.; Yavuz, Hasbi

    1998-02-01

    The maximum cooling density of a Stirling refrigerator operating in a closed regenerative thermodynamic cycle is presented in this paper. The cooling density is the cooling load per unit volume of the refrigerator. Since the size of the refrigerator is involved in the cooling density, the maximization of the cooling density has given a critical compression ratio. The maximum cooling density serves as a better comparison criterion for thermoeconomic considerations.

  16. Studies on capillary tube expansion device used in J-T refrigerators operating with nitrogen-hydrocarbon mixtures

    Science.gov (United States)

    Harish Kruthiventi, S. S.; Venkatarathnam, G.

    2017-10-01

    Capillary tube expansion devices are used extensively in small closed cycle J-T refrigerators operating with refrigerant mixtures due to its low cost and the absence of any moving parts. It is possible for J-T refrigerators operating with mixtures that the velocity of refrigerant mixture at capillary tube outlet reaches a value where it equals the speed of sound at certain conditions. The variation of the speed of sound of nitrogen-hydrocarbon mixtures used in J-T refrigerators has been studied in two phase (vapour-liquid) and three-phase (Vapour-liquid-liquid) region as a function of temperature and pressure in this work. Also the conditions under which choking occurs in practical J-T refrigerators is investigated.

  17. Stirling Refrigerator

    Science.gov (United States)

    Kagawa, Noboru

    A Stirling cooler (refrigerator) was proposed in 1862 and the first Stirling cooler was put on market in 1955. Since then, many Stirling coolers have been developed and marketed as cryocoolers. Recently, Stirling cycle machines for heating and cooling at near-ambient temperatures between 173 and 400K, are recognized as promising candidates for alternative system which are more compatible with people and the Earth. The ideal cycles of Stirling cycle machine offer the highest thermal efficiencies and the working fluids do not cause serious environmental problems of ozone depletion and global warming. In this review, the basic thermodynamics of Stirling cycle are briefly described to quantify the attractive cycle performance. The fundamentals to realize actual Stirling coolers and heat pumps are introduced in detail. The current status of the Stirling cycle machine technologies is reviewed. Some machines have almost achieved the target performance. Also, duplex-Stirling-cycle and Vuilleumier-cycle machines and their performance are introduced.

  18. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1999-01-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilities access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  19. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1996-07-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  20. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1996-11-15

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  1. Optimized heat exchanger unit in a thermoacoustic refrigerator

    Science.gov (United States)

    El-Fawal, Mawahib Hassan; Mohd-Ghazali, Normah

    2012-06-01

    Due to concern over the environmental impact caused by hazardous refrigerants, the last ten years or so has seen increasing research into thermoacoustic refrigeration. A thermoacoustic refrigerator is a device which uses acoustic power to pump heat. It holds the merits of simple mechanical design, absence of harmful refrigerants and having no or few moving parts. However, the performance of the thermoacoustic refrigerator, particularly the standing wave types, is currently not competitive compared to its counterpart conventional vapor-compression refrigerator. Thermoacoustic refrigeration prototypes, built up-to-date, achieved 0.1-0.2 relative coefficient of performance (COPR) compared with that of 0.33-0.5 for the conventional vapor-compression refrigerators. The poor heat exchanger design is one of the reasons for this poor efficiency. This paper discussed the influence of the thermoacoustic refrigerator heat exchanger's parameters on its design and the optimization of the performance of the system using the Lagrange multiplier method. The results showed that, the dissipated power is less than the published value by about 49% in the cold heat exchanger and about 38.5% in the hot heat exchanger. Furthermore, the increase of the cold heat exchanger effectiveness is found to be 3%. Thus, the decrease in the dissipated power in both heat exchangers with effective cold heat exchanger increases the performance of the thermoacoustic refrigerator.

  2. Zero-ODP Refrigerants for Low Tonnage Centrifugal Chiller Systems

    National Research Council Canada - National Science Library

    Gui, Fulin

    1996-01-01

    ..., HFC-236cb, HFC-236fa, HFC-245cb, and HFC-254cb, for centrifugal chiller applications. We took into account the thermodynamic properties of the refrigerant and aerodynamic properties of the impeller compression process to this evaluation...

  3. Optimization of Multi-layer Active Magnetic Regenerator towards Compact and Efficient Refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein

    2016-01-01

    Magnetic refrigerators can theoretically be more efficient than current vapor compression systems and use no vapor refrigerants with global warming potential. The core component, the active magnetic regenerator (AMR) operates based on the magnetocaloric effect of magnetic materials and the heat r....... In addition, simulations are carried out to investigate the potential of applying nanofluid in future magnetic refrigerators....

  4. Conversion of cold beverage dispenser's refrigeration system to R744 refrigerant

    OpenAIRE

    Visek, Matej; Elbel, Stefan; Hrnjak, Pega

    2016-01-01

    Cold beverage dispensers belong to the group of light commercial refrigeration machines that includes beverage coolers, ice machines and storage units for food items. Beverage dispensers use a vapor compression system to charge a thermal storage, usually an ice bank, which is used to indirectly cool tap water and beverage concentrate. For these machines, R290 (propane) and R744 (carbon dioxide) are among the favorite candidates to completely replace high GWP HFC refrigerants in the future. Be...

  5. REFRIGERATION ESPECIALLY FOR VERY LOW TEMPERATURES

    Science.gov (United States)

    Kennedy, P.B.; Smith, H.R. Jr.

    1960-09-13

    A refrigeration system for producing very low temperatures is described. The system of the invention employs a binary mixture refrigerant in a closed constant volume, e.g., Freon and ethylene. Such mixture is compressed in the gaseous state and is then separated in a fractionating column element of the system. Thenceforth, the first liquid to separate is employed stagewise to cool and liq uefy successive portions of the refrigerant at successively lower temperatures by means of heat exchangers coupled between the successive stages. When shut down, all of the volumes of the system are interconnected and a portion of the refrigerant remains liquid at ambient temperatures so that no dangerous overpressures develop. The system is therefore rugged, simple and dependable in operation.

  6. Microminiature Refrigeration

    Science.gov (United States)

    Little, W. A.

    2008-03-01

    The dramatic growth of industrial cryogenics in the past century has overshadowed the need for cryogenics on a smaller scale. Today, small scale, MEMS or microminiature refrigerators constitute a small part of the field, but one with a unique role to play, often in instrumentation. Key attributes of these coolers have proved to be their small size, low noise, fast response, and low cost. The small size has enabled the integration of the instrument and cooler. The fast response and low noise have made possible instruments of unique capabilities. Opportunities exist for the seamless integration of cryogenics in other products, but to succeed here, companies need strength in both cryogenics and a broad range of other disciplines, including materials science, electronics, and software. To offset economies of scale, new fabrication technologies have had to be created, and others are needed. Some key elements remain to be developed before more widespread use of this technology will be seen. Better miniature heat exchangers and regenerators are needed. Development of miniature compressors to power the coolers could herald a new world of cooled devices analogous to the revolution created by fractional horsepower electric motors in the past fifty years. Opportunities abound!

  7. REFRIGERANT/LUBRICANT MIXTURES: PROBLEMS OF APPLICATION AND PROPERTY RESEARCH

    Directory of Open Access Journals (Sweden)

    Yu. Semenyuk

    2013-10-01

    Full Text Available The results and generalizations of thermophysical property research for the refrigerant/lubricant mixtures are summarized. The methodological aspects of the experimental studies of the thermal properties of real working media for vapor compression refrigeration machines and the general principles of the thermodynamic properties simulation for such solutions are analyzed. It is shown that the admixtures of compressor oil in the refrigerant make the efficiency parameters of compressor systems much lower. The question of a selective solubility of the multicomponent refrigerants in compressor oils is discussed.

  8. Refrigerating machine oil

    Energy Technology Data Exchange (ETDEWEB)

    Nozawa, K.

    1981-03-17

    Refrigerating machine oil to be filled in a sealed motorcompressor unit constituting a refrigerating cycle system including an electric refrigerator, an electric cold-storage box, a small-scaled electric refrigerating show-case, a small-scaled electric cold-storage show-case and the like, is arranged to have a specifically enhanced property, in which smaller initial driving power consumption of the sealed motor-compressor and easier supply of the predetermined amount of the refrigerating machine oil to the refrigerating system are both guaranteed even in a rather low environmental temperature condition.

  9. Progress in magnetic refrigeration and future challenges

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Pryds, Nini

    2014-01-01

    refrigerators have the potential for high efficiency. However, reported device COPs for laboratory devices are still well below commercially available vapor compression systems. In order to significantly improve AMR efficiency, several loss mechanisms must be reduced and other aspects of system design...

  10. A LiBr-H2O Absorption Refrigerator Incorporating a Thermally Activated Solution Pumping Mechanism

    OpenAIRE

    Ian W. Eames

    2017-01-01

    This paper provides an illustrated description of a proposed LiBr-H2O vapour absorption refrigerator which uses a thermally activated solution pumping mechanism that combines controlled variations in generator vapour pressure with changes it produces in static-head pressure difference to circulate the absorbent solution between the generator and absorber vessels. The proposed system is different and potentially more efficient than a bubble pump system previously proposed and avoids the need f...

  11. Manufacturing A Refrigerator with Heat Recovery Unit

    Directory of Open Access Journals (Sweden)

    Mustafa Mohammed Kadhim

    2018-02-01

    Full Text Available This study aims to exploite the rejected heating energy from condenser and benefit from it to reheat the foods and other materials. It can also be employed to improve the coefficient of performance of a refrigerator at the same time by using approximately the same consumption electrical energy used to operate the compressor and refrigerator in general. This idea has been implemented by manufacturing of a refrigerator with using additional part has the same metal and condenser pipe diameters but its surface area does not exceed 40% from total surface area of the condenser and its design as an insulated cabinet from all sides to prevent heat leakage through it and located between the compressor and the condenser. Small electrical fan has been added inside this cabinet to provide a suitable air circulation and a homogenous temperature distribution inside the cabinet space. It is expected that the super heating energy of refrigerant (R134a which comes out of the compressor would be removed  inside this cabinet and this insist to condensate the refrigerant (cooling fluid with a rate higher than that used in the normal refrigerator only. Three magnetic valves have been used in order to control the refrigerant flow in state of operation the refrigerator only or to gather with heating cabinet. To measure the temperatures at each process of the simple vapor compression refrigeration cycle, nine temperature sensors at input and output of each compressor, condenser and an evaporator in additional to input of cabinet and inside it and on evaporator surface have been provided. Five pressure gages have been used to measure the value of pressure and compare it for the two states of operation. The consumption of electrical energy  can be calculated by adding an ammeter and a voltmeter and compare between the consumption energy of both states. The obtained results show that there is an improvement in the coeffecient of performance in state of operation the

  12. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1994-05-27

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  13. Magnetically suspended Stirling cryogenic space refrigerator Status report

    Science.gov (United States)

    Daniels, A.; Gasser, M.; Sherman, A.

    1982-01-01

    At the 1979 Cryogenic Engineering Conference, attention was given to conceptual designs of spaceborne cryogenic refrigeration systems which can provide long-term, unattended operation. Since that time, efforts have continued to translate one of those concepts into an engineering model. The present investigation is concerned with a refrigerator which was designed to generate 5 W of cooling power at a temperature of 65 K. The compression heat of the refrigerator is dissipated at a temperature of 300 K, and the output of the system is to be maintained reliably for a period of five years or longer. The refrigerator design is based on the Stirling cycle, which has an ideal efficiency equal to that of the Carnot cycle. Attention is given to some background information concerning a cryogenic refrigerator, the design of the refrigerator components, and the development status. The magnetic bearings and the linear motors have been tested at the component level.

  14. Experimental And Numerical Investigations of Ejector Jet Refrigeration System With Primary Stream Swirl

    OpenAIRE

    Parveen Banu, Jiautheen; Mallikarjuna, Jawali Maharudrappa; Mani, Annamalai

    2016-01-01

    Among the various heat powered refrigerated systems, vapour jet refrigeration system (VJRS) is attractive because of its simple and rugged nature. Ejector is a key component in VJRS and the performance of the whole system depends on the effective performance of the ejector. Ejector can be operated with low grade energy by utilizing the heat from solar energy, waste heat from industrial exhaust, automobile exhaust, etc, at minimum temperature of about 60°C[1]. Besides that, this system requir...

  15. Performance Analysis of Multipurpose Refrigeration System (MRS on Fishing Vessel

    Directory of Open Access Journals (Sweden)

    Ust Y.

    2016-04-01

    Full Text Available The use of efficient refrigerator/freezers helps considerably to reduce the amount of the emitted greenhouse gas. A two-circuit refrigerator-freezer cycle (RF reveals a higher energy saving potential than a conventional cycle with a single loop of serial evaporators, owing to pressure drop in each evaporator during refrigeration operation and low compression ratio. Therefore, several industrial applications and fish storage systems have been utilized by using multipurpose refrigeration cycle. That is why a theoretical performance analysis based on the exergetic performance coefficient, coefficient of performance (COP, exergy efficiency and exergy destruction ratio criteria, has been carried out for a multipurpose refrigeration system by using different refrigerants in serial and parallel operation conditions. The exergetic performance coefficient criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability. According to the results of the study, the refrigerant R32 shows the best performance in terms of exergetic performance coefficient, COP, exergy efficiency, and exergy destruction ratio from among the other refrigerants (R1234yf, R1234ze, R404A, R407C, R410A, R143A and R502. The effects of the condenser, freezer-evaporator and refrigerator-evaporator temperatures on the exergetic performance coefficient, COP, exergy efficiency and exergy destruction ratios have been fully analyzed for the refrigerant R32.

  16. TRANSPORT PROPERTIES FOR REFRIGERANT MIXTURES

    Directory of Open Access Journals (Sweden)

    V. Geller

    2014-06-01

    Full Text Available A set of models to predict viscosity and thermal conductivity of refrigerant mixtures is developed. A general model for viscosity and thermal conductivity use the three contributions sum form (the dilute-gas terms, the residual terms, and the liquid terms. The corresponding states model is recommended to predict the dense gas transport properties over a range of reduced density from 0 to 2. It is shown that the RHS model provides the most reliable results for the saturated-liquid and the compressed-liquid transport properties over a range of given temperatures from 0,5 to 0,95.

  17. Screw Compressor Characteristics for Helium Refrigeration Systems

    Science.gov (United States)

    Ganni, V.; Knudsen, P.; Creel, J.; Arenius, D.; Casagrande, F.; Howell, M.

    2008-03-01

    The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression. At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss mechanisms, as well as to implement practical solutions.

  18. A Study of the Heat Transfer Coefficient of a Mini Channel Evaporator with R-134a as Refrigerant

    Science.gov (United States)

    Dollera, E. B.; Villanueva, E. P.

    2015-09-01

    The present study is to evaluate the heat transfer coefficient of the minichannel copper blocks used as evaporator with R-134a as the refrigerant. Experiments were conducted using three evaporator specimens of different channel hydraulic diameters (1.0mm, 2.0mm, 3.0mm). The total length for each channel is 640 mm. The dimension of each is 100mm.x50mm.x20mm. and the outside surfaces were machined to have fins. They were connected to a standard vapour compression refrigeration system. During each run of the experiment, the copper block evaporator was placed inside a small wind tunnel where controlled flow of air from a forced draft fan was introduced for the cooling process. The experimental set-up used data acquisition software and computer-aided simulation software was used to simulate the pressure drop and temperature profiles of the evaporator during the experimental run. The results were then compared with the Shah correlation. The Shah correlation over predicted and under predicted the values as compared with the experimental results for all of the three diameters and high variation for Dh=1.0mm. This indicates that the Shah correlation at small diameters is not the appropriate equation for predicting the heat transfer coefficient. The trend of the heat transfer coefficient is increasing as the size of the diameter increases.

  19. Status of not-in-kind refrigeration technologies for household space conditioning, water heating and food refrigeration

    National Research Council Canada - National Science Library

    Bansal, Pradeep; Vineyard, Edward Allan; Abdelaziz, Omar

    2012-01-01

    .... These alternative technologies include: thermoacoustic refrigeration, thermoelectric refrigeration, thermotunneling, magnetic refrigeration, Stirling cycle refrigeration, pulse tube refrigeration, Malone cycle refrigeration, absorption...

  20. Vuilleumier Cycle Cryogenic Refrigeration

    Science.gov (United States)

    1976-04-01

    changing pressure to produce a cooling effect is similar to that of the cold section of the Stirling cycle refrigerator , since the method by which the...AFFDL-TR-76-17 VUILLEUMIER CYCLE CRYOGENIC REFRIGERATION ENVIRONMENTAL CONTROL BRANCH 4 VEHICLE EQUIPMENT DIVISION APRIL 1976 TECHNICAL REPORT AFFDL...WORDS (Continue on reverse side if necessary and identify by block number) Cryogenic Refrigerator Vuilleumier Cycle 20. ABSTRACT (Continue on reverse

  1. Study on the dynamic characteristics, refrigerant and lubricating oil in the high-pressure hermetic compressor.

    Science.gov (United States)

    Okada, Tetsuji

    The dynamics characteristics and refrigerant and lubricating oil in the high-pressure hermeti compressor has been studied. The compressor is 1 HP for the air conditioner of home use. The experiment and the analytic simulation have been researched. As a result, the theoretic compressor model was proposed. This model has three processes inside of compressor. They are the suction process, the compression process, and the discharge process. In each process, mass equations and energy equations are considered. Also, the inlet refrigerant conditions (2-phase refrigerant) were simulated and the dynamic characteristics of refrigerant and refrigerant and lubricating oil at starting was obtaied.

  2. New Regenerative Cycle for Vapor Compression Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bergander, Mark J [Magnetic Development, Inc.; Butrymowicz, Dariusz [Polish Academy of Scinces

    2010-01-26

    This project was a continuation of Category 1 project, completed in August 2005. Following the successful bench model demonstration of the technical feasibility and economic viability, the main objective in this stage was to fabricate the prototype of the heat pump, working on the new thermodynamic cycle. This required further research to increase the system efficiency to the level consistent with theoretical analysis of the cycle. Another group of objectives was to provide the foundation for commercialization and included documentation of the manufacturing process, preparing the business plan, organizing sales network and raising the private capital necessary to acquire production facilities.

  3. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1998-08-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufactures and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on many refrigerants including propane, ammonia, water, carbon dioxide, propylene, ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

  4. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1997-02-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alterative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on various refrigerants. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

  5. Thermoacoustically driven refrigerator with double thermoacoustic-Stirling cycles

    Science.gov (United States)

    Luo, Ercang; Dai, Wei; Zhang, Yong; Ling, Hong

    2006-02-01

    Recently, considerable research efforts have been made to search substitution technologies for chlorofluorocarbon-based vapor compression cycles due to the concern over environmental issues. This letter introduces a helium-based thermoacoustic refrigeration system, which is a thermoacoustic-Stirling refrigerator driven by a thermoacoustic-Stirling heat engine, for domestic refrigeration purpose. In the regenerators of both the refrigerator and the prime mover, helium gas experiences near to reversible high efficiency Stirling process. At the operating point with 3.0MPa mean pressure, 57.7Hz frequency, and 2.2kW heat input, the experimental cooler provides a lowest temperature of -64.4°C and 250W cooling power at -22.1°C. These results show good potential of the system to be an alternative in near future for domestic refrigeration with advantages of environment-friendliness, no moving parts, and heat driven mechanism.

  6. Simulation of Thermodynamics Aspects about Pulse Tube Refrigerator

    Science.gov (United States)

    Hozumi, Yoshikazu; Shiraishi, Masao; Murakami, Masahide

    2004-06-01

    In order to investigate the heat transfer mechanism inside a pulse tube refrigerator, CFD has been applied to simulate the working gas behavior. Three dimensional compressible Navier-Stokes equations with viscous dissipation have been solved. Heat conduction between the working gas and the tube metal solids are incorporated into the simulation. A Stirling cycle refrigerator has been also simulated to validate the heat transfer mechanism of the pulse tube refrigerator. However, there is a distinctive heat transfer from the cold end to the hot end of pulse tube, the pulse tube works as a gas displacer to induce a phase shift. The heat transfer of pulse tube refrigerator is caused by the same mechanism of Stirling cycle refrigerator. Additionally, thermal convection at an inclined pulse tube on the angle less than horizontal installation is investigated to show simulation capability of the three dimensional modeling.

  7. Materials for Room Temperature Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considere...... cooling is some 40 – 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures.......Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered...... candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material...

  8. Influence of Oil on Refrigerant Evaporator Performance

    Science.gov (United States)

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

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

  9. Properties of Refrigerant Affect Compressor Design

    OpenAIRE

    Bukac, Hubert

    2012-01-01

    The paper examines selected thermodynamic properties of commonly used refrigerants and how they may affect design of a compressor. Among those properties are volumetric capacity, system pressure difference, system compression ratio, isentropic coefficient of performance, gas density, temperature of discharge gas, velocity of sound etc. The is made on the scale of evaporating temperatures from –40 oC to 30 oC, and condensing temperature 40.5 oC. The temperature of gas entering suction port is ...

  10. Refrigerants and environment

    Science.gov (United States)

    Tsvetkov, O. B.; Laptev, Yu A.

    2017-11-01

    The refrigeration and air-conditioning industries are important sectors of the economy and represents about 15 % of global electricity consumptions. The chlorofluorocarbons also called CFCs are a class of refrigerants containing the halogens chlorine and/or fluorine on a carbon skeleton. Because of their environmental impact the Montreal Protocol was negotiated in 1987 to limit the production of certain CFCs and hydrochlirofluorocarbons (HCFCs) in developed and developing countries. The halogenated refrigerants are depleting the ozone layer also major contribution to the greenhouse effect. To be acceptable as a refrigerant a fluid must satisfy a variety of thermodynamic criteria and should be environment friendly with zero Ozone Depletion Potential and low Global Warming Potential. The perspective of a future phase down of HFCs is considered in this report taking into account a strategy for the phase out of HCFCs and perspective of choosing of various refrigerant followed by safety issues.

  11. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1992-04-30

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air- conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on R-32, R-123, R-124, R- 125, R-134a, R-141b, R142b, R-143a, R-152a, R-290 (propane), R-717 (ammonia), ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses polyalkylene glycol (PAG), ester, and other lubricants. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits.

  12. closed cycle solar refrigeration with the calcium chloride system

    African Journals Online (AJOL)

    user

    1986-09-01

    Sep 1, 1986 ... gives an option tree of the alternative schemes. When the energy of the vapour compression machine is solar, the electrical power for driving the compressor can be provided by photovoltaic panels. Alternatively, a concentrating or flat plate solar collector may be used to replace the boiler in a rankine cycle.

  13. Development of a refrigeration system for lunar surface and spacecraft applications

    Science.gov (United States)

    Copeland, R. J.

    1976-01-01

    An evaluation of refrigeration devices suitable for potential lunar surface and spacecraft applications was performed. The following conclusions were reached: (1) the vapor compression system is the best overall refrigeration system for lunar surface and spacecraft applications and the single phase radiator system is generally preferred for earth orbit applications, (2) the vapor compression cycle may have some application for simultaneous heating and cooling, (3) a Stirling cycle refrigerator was selected for the manned cabin of the space shuttle, and (4) significant increases in payload heat rejection can be obtained by a kit vapor compression refrigerator added to the shuttle R-21 loop. The following recommendations were made: (1) a Stirling cycle refrigerator may be used for food freezer and biomedical sample storage, (2) the best system for a food freezer/experiments compartment for an earth orbit space station has not been determined, (3) a deployed radiator system can be designed for large heat loads in earth orbit.

  14. Pulse Tube Refrigerator

    Science.gov (United States)

    Matsubara, Yoichi

    The pulse tube refrigerator is one of the regenerative cycle refrigerators such as Stirling cycle or Gifford-McMahon cycle which gives the cooling temperature below 150 K down to liquid helium temperature. In 1963, W. E. Gifford invented a simple refrigeration cycle which is composed of compressor, regenerator and simple tube named as pulse tube which gives a similar function of the expander in Stirling or Gifford-McMahon cycle. The thermodynamically performance of this pulse tube refrigerator is inferior to that of other regenerative cycles. In 1984, however, Mikulin and coworkers made a significant advance in pulse tube configuration called as orifice pulse tube. After this, several modifications of the pulse tube hot end configuration have been developed. With those modifications, the thermodynamic performance of the pulse tube refrigerator became the same order to that of Stirling and Gifford-McMahon refrigerator. This article reviews the brief history of the pulse tube refrigerator development in the view point of its thermodynamically efficiency. Simplified theories of the energy flow in the pulse tube have also been described.

  15. Magnetic refrigeration down to 1.6 K for the future circular collider e$^+$e$^-$

    CERN Document Server

    Tkaczuk, Jakub; Millet, Francois; Rousset, Bernard; Duval, Jean Marc

    2017-01-01

    High-field superconducting rf cavities of the future circular collider e+e− may require a kW-range superfluid helium refrigeration down to 1.6 K. Magnetic refrigeration operating below 4.2 K can be an alternative to the compression/expansion helium refrigeration. A significant difference between this application and previous magnetic refrigerator studies is its large cooling power, up to 103 times larger than the other designs. Principles of magnetic refrigeration are described and various technical solutions are compared. A numerical model for the static magnetic refrigerator is presented, validated, and adapted to the needs of the positron-electron version of the future circular collider. A preliminary design of magnetic refrigerator suitable for low temperature, kW-range cooling is studied.

  16. The toxicity of refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1996-07-01

    This paper presents toxicity data and exposure limits for refrigerants. The data address both acute (short-term, single exposure) and chronic (long-term, repeated exposure) effects, with emphasis on the former. The refrigerants covered include those in common use for the last decade, those used as components in alternatives, and selected candidates for future replacements. The paper also reviews the toxicity indicators used in both safety standards and building, mechanical, and fire codes. It then outlines current classification methods for refrigerant safety and relates them to standard and code usage.

  17. Unfired clay bricks – moisture properties and compressive strength

    DEFF Research Database (Denmark)

    Hansen, E.J. de Place; Hansen, Kurt Kielsgaard

    2002-01-01

    Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive str...

  18. Optimization of Multi-layer Active Magnetic Regenerator towards Compact and Efficient Refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein

    2016-01-01

    Magnetic refrigerators can theoretically be more efficient than current vapor compression systems and use no vapor refrigerants with global warming potential. The core component, the active magnetic regenerator (AMR) operates based on the magnetocaloric effect of magnetic materials and the heat...

  19. Quantum-circuit refrigerator

    Science.gov (United States)

    Tan, Kuan Yen; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Masuda, Shumpei; Möttönen, Mikko

    2017-05-01

    Quantum technology promises revolutionizing applications in information processing, communications, sensing and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains challenging in many solid-state implementations, such as superconducting circuits. Here we demonstrate direct cooling of a superconducting resonator mode using voltage-controllable electron tunnelling in a nanoscale refrigerator. This result is revealed by a decreased electron temperature at a resonator-coupled probe resistor, even for an elevated electron temperature at the refrigerator. Our conclusions are verified by control experiments and by a good quantitative agreement between theory and experimental observations at various operation voltages and bath temperatures. In the future, we aim to remove spurious dissipation introduced by our refrigerator and to decrease the operational temperature. Such an ideal quantum-circuit refrigerator has potential applications in the initialization of quantum electric devices. In the superconducting quantum computer, for example, fast and accurate reset of the quantum memory is needed.

  20. Quantum-circuit refrigerator

    Science.gov (United States)

    Tan, Kuan Yen; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Masuda, Shumpei; Möttönen, Mikko

    2017-01-01

    Quantum technology promises revolutionizing applications in information processing, communications, sensing and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains challenging in many solid-state implementations, such as superconducting circuits. Here we demonstrate direct cooling of a superconducting resonator mode using voltage-controllable electron tunnelling in a nanoscale refrigerator. This result is revealed by a decreased electron temperature at a resonator-coupled probe resistor, even for an elevated electron temperature at the refrigerator. Our conclusions are verified by control experiments and by a good quantitative agreement between theory and experimental observations at various operation voltages and bath temperatures. In the future, we aim to remove spurious dissipation introduced by our refrigerator and to decrease the operational temperature. Such an ideal quantum-circuit refrigerator has potential applications in the initialization of quantum electric devices. In the superconducting quantum computer, for example, fast and accurate reset of the quantum memory is needed. PMID:28480900

  1. Public Refrigerated Warehouses

    Data.gov (United States)

    Department of Homeland Security — The International Association of Refrigerated Warehouses (IARW) came into existence in 1891 when a number of conventional warehousemen took on the demands of storing...

  2. Refrigeration oils for low GWP refrigerants in various applications

    Science.gov (United States)

    Saito, R.; Sundaresan, S. G.

    2017-08-01

    The practical use of the refrigeration systems is considered as a methods to suppress global warming. The replacement of a refrigerant with a new one that has lower global warming potential (GWP) has been underway for several years. For the application fields of refrigerators, domestic air conditioners, automotive air conditioners and hot water dispensers, the investigation has almost finished. It is still underway for the application fields of commercial air conditioners and chillers, refrigeration facilities for cold storage, etc. And now, the refrigeration system is being applied in various ways to decrease global warming above the generation of electric power with organic Rankine cycle, the binary electric generation with ground source heat pump, and so on. In these situations, various refrigerants are developed and several kinds of suitable refrigeration oils are selected. This paper presents the consideration of suitable refrigeration oil for the various low GWP refrigerants.

  3. Chemical Safety Alert: Hazards of Ammonia Releases at Ammonia Refrigeration Facilities

    Science.gov (United States)

    Anhydrous ammonia is used as a refrigerant in mechanical compression systems, often liquefied under pressure which increases exposure risk due to potential for rapid release into the air as a toxic gas.

  4. Refrigerated display cabinets; Butikskyla

    Energy Technology Data Exchange (ETDEWEB)

    Fahlen, Per

    2000-07-01

    This report summarizes experience from SP research and assignments regarding refrigerated transport and storage of food, mainly in the retail sector. It presents the fundamentals of heat and mass transfer in display cabinets with special focus on indirect systems and secondary refrigerants. Moreover, the report includes a brief account of basic food hygiene and the related regulations. The material has been compiled for educational purposes in the Masters program at Chalmers Technical University.

  5. Refrigeration systems and applications

    CERN Document Server

    Dincer, Ibrahim

    2010-01-01

    Refrigeration Systems and Applications, 2nd edition offers a comprehensive treatise that addresses real-life technical and operational problems, enabling the reader to gain an understanding of the fundamental principles and the practical applications of refrigeration technology. New and unique analysis techniques (including exergy as a potential tool), models, correlations, procedures and applications are covered, and recent developments in the field are included - many of which are taken from the author's own research activities in this area. The book also includes so

  6. Materials for room temperature magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Rosendahl Hansen, B.

    2010-07-15

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 - 310 K. A magnetic refrigerant should fulfill a number of criteria, among these a large magnetic entropy change, a large adiabatic temperature change, preferably little to no thermal or magnetic hysteresis and the material should have the stability required for long term use. As the temperature range required for room temperature cooling is some 40 - 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures. (Author)

  7. Performance investigation of vapour recompressed batch distillation for separating ternary wide boiling constituents

    Directory of Open Access Journals (Sweden)

    Rohith R Nair

    2017-12-01

    Full Text Available The vapour recompression scheme (VRC has been very effective in continuous distillation for energy intensification. The applicability of this scheme for the separation of multicomponent wide boiling constituents in batch distillation is a major challenge, because of the unsteady nature of the batch. In this study, the vapour recompression scheme has been implemented for the separation of multicomponent wide boiling constituents in the batch distillation. For the optimal usage of energy from compressed vapours manipulation of top tray vapour or external energy is done. A comparative study of the vapour recompressed batch distillation having a variable speed single compressor (SVRBD and double stage compressor (DVRBD with conventional batch distillation in terms of energy savings and total annualized cost is done. The VRC schemes achieve an energy savings of 50% and 10.03% total annualized cost (TAC for SVRBD and DVRBD achieve 52% energy savings and 12.21% TAC with a payback period of 10 years. Keywords: Batch distillation, Vapour recompression, Wide boiling constituents, Energy saving, Total annualized cost

  8. An overview of adsorptive processes in refrigeration systems

    Directory of Open Access Journals (Sweden)

    Wolak Eliza

    2016-01-01

    Full Text Available Economic reasons and quest for new solutions based on recovering the energy have provoked an increase of interest in the adsorption technology in the refrigeration industry. The confirmation can be the fact that number of published research is on rise. Adsorption appliances may turn out to be an alternative to compression-type coolers. They use ecological chemical agents instead of substances which are aggressive and harmful to the environment. For regeneration of adsorptive refrigeration systems one can use cheap energy in a form of: industrial waste heat, energy of solar radiation and cheap electric power. The paper presents principles of operation as well as advantages and disadvantages of adsorptive refrigeration systems. Basing on literature the most frequently used adsorbent – adsorbate systems – which are employed in refrigeration industry – have been characterized. A review of construction solutions of systems on both laboratory and industrial scale has been made.

  9. Optimization of refrigeration system with gas-injected scroll compressor

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Baolong; Shi, Wenxing; Han, Linjun; Li, Xianting [Department of Building Science, Tsinghua University, Beijing 100084 (China)

    2009-11-15

    Gas refrigerant injection has been proven as an effective method to improve the performance of the scroll compressor and its refrigeration system under high compression ratio working conditions. Much research on the injected scroll compressor and its system has been conducted, but the universal control and design method is still lacking. A model of the refrigeration system with a gas-injected scroll compressor is developed in this paper. With this model, the effects of gas injection on the system and component parameters are investigated. Based on the identified evaporator characteristics and thermodynamic analysis, a set of general principles for the design and operation of the refrigeration or heat pump system with a gas-injected scroll compressor is proposed. (author)

  10. Modelling and simulation of regenerators with complex flow arrangements for active magnetocaloric refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

    2014-01-01

    Compared to a conventional vapor compression refrigera-tion system, a magnetocaloric refrigerator has many advantages, such as potentially high efficiency, low vibration and avoidance of refrigerants that deplete the ozone layer and cause the green-house effect. As a main component of the active...... magnetic re-generative refrigerator, the regenerator plays an important role in the cooling performance and efficiency of the whole system. However, the regenerator design is constrained by several exter-nal factors, such as the geometry of the magnetic field source and flow resistance. In this work, novel...

  11. Intercomparison on measurement of water vapour permeability

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard

    Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001).......Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001)....

  12. Gas and vapour detection using polypyrrole

    NARCIS (Netherlands)

    Leur, R.H.M. van de; Waal, A. van der

    1999-01-01

    The vapours of organic solvents like toluene, butanon, and ethanol do effect the electrical conductivity of electrochemically synthesised polypyrrole. This property allows the use of polypyrrole in sensors for vapour detection. The conductivity is also a function of temperature and the history of

  13. Low Global Warming Potential Refrigerants for Commercial Refrigeration Systems

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Brian A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sharma, Vishaldeep [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-01

    Supermarket refrigeration systems account for approximately 50% of supermarket energy use, placing this class of equipment among the highest energy consumers in the commercial building domain. In addition, the commonly used refrigeration system in supermarket applications is the multiplex direct expansion (DX) system, which is prone to refrigerant leaks due to its long lengths of refrigerant piping. This leakage reduces the efficiency of the system and increases the impact of the system on the environment. The high Global Warming Potential (GWP) of the hydrofluorocarbon (HFC) refrigerants commonly used in these systems, coupled with the large refrigerant charge and the high refrigerant leakage rates leads to significant direct emissions of greenhouse gases into the atmosphere. Environmental concerns are driving regulations for the heating, ventilating, air-conditioning and refrigeration (HVAC&R) industry towards lower GWP alternatives to HFC refrigerants. Existing lower GWP refrigerant alternatives include hydrocarbons, such as propane (R-290) and isobutane (R-600a), as well as carbon dioxide (R-744), ammonia (R-717), and R-32. In addition, new lower GWP refrigerant alternatives are currently being developed by refrigerant manufacturers, including hydrofluoro-olefin (HFO) and unsaturated hydrochlorofluorocarbon (HCFO) refrigerants. The selection of an appropriate refrigerant for a given refrigeration application should be based on several factors, including the GWP of the refrigerant, the energy consumption of the refrigeration system over its operating lifetime, and leakage of refrigerant over the system lifetime. For example, focusing on energy efficiency alone may overlook the significant environmental impact of refrigerant leakage; while focusing on GWP alone might result in lower efficiency systems that result in higher indirect impact over the equipment lifetime. Thus, the objective of this Collaborative Research and Development Agreement (CRADA) between

  14. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Cain, J.M. (Calm (James M.), Great Falls, VA (United States))

    1993-04-30

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included. The database identifies sources of specific information on R-32, R-123, R-124, R-125, R-134, R-134a, R-141b, R-142b, R-143a, R-152a, R-245ca, R-290 (propane), R-717 (ammonia), ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, ester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents to accelerate availability of the information and will be completed or replaced in future updates.

  15. Experimental studies on a vapour compression system using ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 9 (2011) >. Log in or Register to get access to full text downloads.

  16. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1992-11-09

    The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air- conditioning and refrigeration equipment. The database identifies sources of specific information on R-32, R-123, R-124, R-125, R-134, R-134a, R-141b, R-142b, R-143a, R-152a, R-245ca, R-290 (propane), R- 717 (ammonia), ethers, and others as well as azeotropic and zeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, ester, and other synthetics as well as mineral oils. It also references documents on compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. A computerized version is available that includes retrieval software.

  17. Indirect refrigeration systems with natural refrigerants

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard; Christensen, Kim Gardø; Jensen, Per Henrik

    1998-01-01

    Heat transfer for boiling and condensing carbon dioxide has been investigated.Heat transfer for carbon dioxide evaporating inside pipe has been measured and compared with Shah's correlation. The measured heat transfer coefficient is much higher than the value determined with the correlation.A she......-and-tube heat exchanger with carbon dioxide on the shell side and flow ice inside the tubes has been used to investigate the heat transfer for condensing carbon dioxide.At leats is mentioned results obtained with a frozen food display case using carbone dioxide as refrigerant....

  18. Refrigeration a history

    CERN Document Server

    Gantz, Carroll

    2015-01-01

    For thousands of years, humans coped with heat by harvesting and storing natural ice and devising natural cooling systems that utilized ventilation and evaporation. By the mid 1800s, people began developing huge refrigeration machines to manufacture ice. By the early 1900s, engineers developed electric domestic refrigerators, which by 1927 were affordable convenient household appliances. By then, an increasingly sophisticated public demanded more modern-looking appliances than engineers could produce, and a new breed of designers entered the manufacturing world to provide them. During the Depr

  19. Refrigeration Playbook: Natural Refrigerants; Selecting and Designing Energy-Efficient Commercial Refrigeration Systems That Use Low Global Warming Potential Refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Caleb [CTA Architects Engineers, Boise, ID (United States); Reis, Chuck [CTA Architects Engineers, Boise, ID (United States); Nelson, Eric [CTA Architects Engineers, Boise, ID (United States); Armer, James [CTA Architects Engineers, Boise, ID (United States); Arthur, Rob [CTA Architects Engineers, Boise, ID (United States); Heath, Richard [CTA Architects Engineers, Boise, ID (United States); Rono, James [CTA Architects Engineers, Boise, ID (United States); Hirsch, Adam [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-03-01

    This report provides guidance for selecting and designing energy efficient commercial refrigeration systems using low global warming potential refrigerants. Refrigeration systems are generally the largest energy end use in a supermarket type building, often accounting for more than half of a building's energy consumption.

  20. Portable refrigerant charge meter and method for determining the actual refrigerant charge in HVAC systems

    Science.gov (United States)

    Gao, Zhiming; Abdelaziz, Omar; LaClair, Tim L.

    2017-08-08

    A refrigerant charge meter and a method for determining the actual refrigerant charge in HVAC systems are described. The meter includes means for determining an optimum refrigerant charge from system subcooling and system component parameters. The meter also includes means for determining the ratio of the actual refrigerant charge to the optimum refrigerant charge. Finally, the meter includes means for determining the actual refrigerant charge from the optimum refrigerant charge and the ratio of the actual refrigerant charge to the optimum refrigerant charge.

  1. Improved cryogenic refrigeration system

    Science.gov (United States)

    Higa, W. H.

    1967-01-01

    Two-position shuttle valve simplifies valving arrangement and crank-shaft configuration in gas-balancing and Stirling-cycle refrigeration systems used to produce temperatures below 173 degrees K. It connects the displacer and regenerator alternately to the supply line or the return line of the compressor, and establishes constant pressure on the drive piston.

  2. Cryogenic Optical Refrigeration

    Science.gov (United States)

    2012-03-22

    study by Ball Aerospace Corporation showed that rare-earth-based optical refrigeration can outperform conventional thermoelectric and mechanical coolers...J. Cryst. Growth 30(1), 21–26 (1975). 139. J. S. Abell, I. R. Harris, B. Cockayne, and J. G. Plant , “A DTA study of zone-refined LiRF4 (R = Y,Er

  3. Performance of Screw Compressor for Small-Capacity Helium Refrigerators

    Science.gov (United States)

    Urashin, Masayuki; Matsubara, Katsumi; Izunaga, Yasushi

    A helium compressor is one of the important components comprising a cryogenic refrigerator. The purpous of this investigation is to develop a new small-capacity helium screw compressor. The performance of a single-stage compressor at high compression ratio and the cooling performance of the compressor are investigated. A semi-hermetic screw compressor with new profile screw rotors, with which high performance can be obtained, is utilized in this investigation. Lubricating oil is applied to cool the compressor motor and the compressed gas. As a result, an overall isentropic efficiency of 80% is obtained when helium is compressed to a compression ratio of 19.8 with a single-stage screw compressor. At the same time, the temperature of a compressor motor and discharge gas can be maintained at low levels. Therefore, it is found that a single-stage screw compressor can compress helium to high compression ratio.

  4. Design and Thermodynamic Analysis of a Steam Ejector Refrigeration/Heat Pump System for Naval Surface Ship Applications

    Directory of Open Access Journals (Sweden)

    Cüneyt Ezgi

    2015-12-01

    Full Text Available Naval surface ships should use thermally driven heating and cooling technologies to continue the Navy’s leadership role in protecting the marine environment. Steam ejector refrigeration (SER or steam ejector heat pump (SEHP systems are thermally driven heating and cooling technologies and seem to be a promising technology to reduce emissions for heating and cooling on board naval surface ships. In this study, design and thermodynamic analysis of a seawater cooled SER and SEHP as an HVAC system for a naval surface ship application are presented and compared with those of a current typical naval ship system case, an H2O-LiBr absorption heat pump and a vapour-compression heat pump. The off-design study estimated the coefficient of performances (COPs were 0.29–0.11 for the cooling mode and 1.29–1.11 for the heating mode, depending on the pressure of the exhaust gas boiler at off-design conditions. In the system operating at the exhaust gas boiler pressure of 0.2 MPa, the optimum area ratio obtained was 23.30.

  5. Stirling cycle engine and refrigeration systems

    Science.gov (United States)

    Higa, W. H. (Inventor)

    1976-01-01

    A Stirling cycle heat engine is disclosed in which displacer motion is controlled as a function of the working fluid pressure P sub 1 and a substantially constant pressure P sub 0. The heat engine includes an auxiliary chamber at the constant pressure P sub 0. An end surface of a displacer piston is disposed in the auxiliary chamber. During the compression portion of the engine cycle when P sub 1 rises above P sub 0 the displacer forces the working fluid to pass from the cold chamber to the hot chamber of the engine. During the expansion portion of the engine cycle the heated working fluid in the hot chamber does work by pushing down on the engine's drive piston. As the working fluid pressure P sub 1 drops below P sub 0 the displacer forces most of the working fluid in the hot chamber to pass through the regenerator to the cold chamber. The engine is easily combinable with a refrigeration section to provide a refrigeration system in which the engine's single drive piston serves both the engine and the refrigeration section.

  6. Autonomous Chemical Vapour Detection by Micro UAV

    Directory of Open Access Journals (Sweden)

    Kent Rosser

    2015-12-01

    Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

  7. On water vapour transfer inside frozen packs

    National Research Council Canada - National Science Library

    Heiss, R

    1971-01-01

    In the case of various foodstuffs, irreversible water- vapour transporations within the frozen packages can bring about a distinct quality drop caused by damage to the surface of the material as a result of drying out (freezer burn...

  8. Applications of magnetic refrigeration and its assessment. A feasibility study - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kitanovski, A.; Diebold, M.; Vuarnoz, D.; Gonin, C.; Egolf, P. W.

    2008-04-15

    Magnetic refrigeration has the potential to replace conventional refrigeration systems - with often problematic refrigerants - in several niche markets or even some main markets of the refrigeration domain. Based on this insight the Swiss Federal Office of Energy has asked a division of the University of Applied Sciences of Western Switzerland (HEIG-VD) in Yverdon-les-Bains to list all possible refrigeration technologies and to evaluate the potential of magnetic refrigeration for these specific applications. The HEIG-VD researchers have developed a calculation tool to determine the coefficient of performance (COP) value and the exergy efficiency as a function of the magnetic field strength and the rotation frequency of a rotary type of magnetic refrigerator. The considered machine design is based on a patent, which was deposited by these scientists. Based on this work, it is found that especially two applications are very interesting for a closer investigation: the household refrigerator without a freezing compartment and the central chilling unit, which may be of large size. In the domains of refrigeration, where magnetic refrigeration could be successfully applied, the costs for magnetic refrigeration machines would be a little higher than those of the conventional ones. On the other hand the study shows possibilities how the magnetic refrigeration machines could reach higher COP values than those of the corresponding gas compression/expansion machines. Therefore, for magnetic refrigeration one may assume lower costs of operation. For large systems - as e.g. chiller units - it should be studied, if superconducting magnets could be economically applied. (author)

  9. Cost Price of Products in the System of Heat, Refrigeration and Electric Energy Production Combined at Thermal Power Plant

    OpenAIRE

    Tubolev Alexander; Romashova Olga; Belyaev Leonid

    2016-01-01

    Nowadays combination of electric, heat and refrigerating energy production (trigeneration) is one of the modern technological solutions for energy efficiency increase and ecological problem solution [1]. Two types of refrigerating machines can be used for both energy and heat production combined: compression aggregates consuming electric energy and absorption aggregates using hot water heat, vapor or other heat conductors.

  10. SIMULACIÓN HORARIA DE UN SISTEMA DE REFRIGERACIÓN COMBINADO EYECTOR-COMPRESIÓN DE VAPOR ASISTIDO POR ENERGÍA SOLAR Y GAS NATURAL HOURLY SIMULATION OF A COMBINED EJECTOR-VAPOR COMPRESSION REFRIGERATION SYSTEM ASSISTED BY SOLAR ENERGY AND NATURAL GAS

    Directory of Open Access Journals (Sweden)

    Humberto Vidal

    2009-04-01

    double stage ejector cooling cycle assisted by solar energy system appears as an attractive solution to this problem. The first stage is performed by a mechanical compression cycle with R-134a as the working fluid, while the second stage is performed by a thermally driven ejector cycle with R-141b. Flat plate collectors and an auxiliary energy burner provide heat to the ejector cycle. This paper describes the hourly simulation of a combined ejector-vapor compression refrigeration system assisted by solar energy and natural gas. The combined solar refrigeration system is modeled using the TRNSYS-EES simulation tool and the typical meteorological year data containing the weather data of Florianópolis Brazil. The results obtained from the computational simulation performed in this system show that the combined ejector-vapor compression cooling cycle is more advantageous than the simple ejector cooling cycle. Finally, the computational model developed in this paper might be used to perform a thermo-economical optimization of the system in future works.

  11. On Refrigerant Compressors

    OpenAIRE

    McGovern, Jim

    1988-01-01

    The purpose of the work was to critically re-examine and investigate the evaluation of refrigerant compressors and to determine and discriminate between the factors which influence their characteristics. The objectives also included the investigation of techniques by which the characteristics can be established and the suggestion of ways in which compressor performance can be described and quantified. The particular compressor which was tested was of the reciprocating open type. Existing theo...

  12. Multilayer Thermionic Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Mahan, G.D.

    1999-08-30

    A review is presented of our program to construct an efficient solid state refrigerator based on thermionic emission of electrons over periodic barriers in the solid. The experimental program is to construct a simple device with one barrier layer using a three layers: metal-semiconductor-metal. The theoretical program is doing calculations to determine: (i) the optimal layer thickness, and (ii) the thermal conductivity.

  13. Development of vapour liquid equilibrium calculation methods for chemical engineering design

    OpenAIRE

    Pokki, Juha-Pekka

    2004-01-01

    This thesis deals with the development of computational methods for vapour liquid equilibrium (VLE) and volumetric properties. The VLE in this thesis can be divided into the low- and medium-pressure VLE with an experimental part and into the high-pressure VLE with a modelling and simulation part. The volumetric properties in this thesis deal with the extension of the model for compressed liquid densities. At low-pressure VLE, the emphasis was on the optimisation of model parameters. Two a...

  14. A feasibility analysis of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry

    Directory of Open Access Journals (Sweden)

    Jankovich Dennis

    2015-01-01

    Full Text Available The thermodynamic analysis demonstrates the feasibility of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry. The main reason for replacement is to reduce the total amount of ammonia in spaces like deep-freezing chambers, daily chambers, working rooms and technical passageways. An ammonia-contaminated area is hazardous to human health and the safety of food products. Therefore the preferred reduced amount of ammonia is accumulated in the Central Refrigeration Engine Room, where the cascade NH3/CO2 device is installed as well. Furthermore, the analysis discusses and compares two left Carnot¢s refrigeration cycles, one for the standard ammonia device and the other for the cascade NH3/CO2 device. Both cycles are processes with two-stage compression and two-stage throttling. The thermodynamic analysis demonstrates that the selected refrigeration cycle is the most cost-effective process because it provides the best numerical values for the total refrigeration factor with respect to the observed refrigeration cycle. The chief analyzed influential parameters of the cascade device are: total refrigeration load, total reactive power, mean temperature of the heat exchanger, evaporating and condensing temperature of the low-temperature part.

  15. THERMOELECTRIC REFRIGERATION USING PELTIER EFFECT

    OpenAIRE

    Prof. Rajendra. P. Patil*, Pradhyumna Suryawanshi, Akshay Pawar, Avdhoot Pawar

    2017-01-01

    In the field of military and medical science there are refrigerators used to cool samples or specimens for preservation. They include refrigeration units for storing blood plasma and other blood products, as well as vaccines and other medical or pharmaceutical supplies. They differ from standard refrigerators used in homes or restaurant because they need to be very hygienic and completely reliable. However, in case of transportation of component from one place to another place there is no ref...

  16. Study on scroll compressor behavior in case of liquid refrigerant injectio

    Science.gov (United States)

    Hirano, Takahisa; Hagimoto, Kiyoshi; Matsuda, Susumu

    Scroll compressors have excellent fundamental features such as high efficiency, high reliability, low vibration and low noise, so scroll compressors have been recently used to heat pump and automotive air conditioners. Furthermore, the development to low temperature applications such as a refrigeration unit has been taken. In the low temperature applications, as the suction gas pressure is very low the compression ratio is very high, and as a result the discharge gas goes to very high temperature. In order to lower discharge gas temperature, refrigerant liquid has been injected into compression pockets. Further, in case of both low temperature usage and heat pump, in order to cool down the motor refrigerant liquid bypass operating system has been adopted. We have theoretically and experimentally studied the scroll compressor behavior in case of liquid refrigerant is existed in the compession pockets. In this paper, we describe these analytical and experimental results.

  17. THERMODYNAMIC PROPERTIES OF SELECTED HFC REFRIGERANTS

    Science.gov (United States)

    Hydrofluorocarbon (HFC) refrigerants are possible alternatives to replace ozone-depleting chlorofluorocarbon and hydrochlorofluorocarbon (HCFC) refrigerants. The flammability of a proposed new refrigerant is a major consideration in assessing its utility for a particular applicat...

  18. Energy series. What about refrigerators and freezers?

    OpenAIRE

    Grisso, Robert D. (Robert Dwight), 1956-; Walker, Martha A.

    2009-01-01

    In most households, the refrigerator is the single biggest energy consuming kitchen appliance. This publication offers tips for choosing the most energy efficient refrigerator or freezer, operating it efficiently, and recycling your old refrigerator.

  19. Cooling transfer fluids: advantages, drawbacks, refrigerant circuit architecture; Les fluides frigoporteurs: avantages, inconvenients, apercu sur l`architecture des circuits frigoporteurs

    Energy Technology Data Exchange (ETDEWEB)

    Duminil, M. [Association Francaise du Froid (AFF), 75 - Paris (France)

    1997-12-31

    The advantages and inconvenients of indirect cooling systems are summarized: simplification of the cooling distribution from a single refrigerating unit, a potential for a larger range of refrigerants, cooling circuit size diminution, but energy consumption increase, lower evaporation temperature, etc. The various types and characteristics of single- and two-phase refrigerant and heat transfer fluids are described, and more especially two-phase liquid-vapour and liquid-solid fluids. Based on the example of a two-temperature-level refrigerating system in a supermarket, the general architecture of the cold distribution circuit and the architecture of the refrigerant circuit itself, are presented with their different types, involving direct or indirect, and centralized or semi-centralized systems

  20. The Freon loop double containment design for Spacelab refrigerator/freezer to protect environment

    Science.gov (United States)

    Hye, A.

    1985-01-01

    General Electric is building a vapor compression refrigerator/freezer for NASA-Johnson Space Center for the Spacelab mission SLS-1 for life sciences experiments. Freon R502 is used as refrigerant. As R502 is considered toxic, the whole Freon loop is enclosed in a second containment to avoid exposure to crewmen. A detailed description of the design and construction of the safety enclosure is presented.

  1. Energy and exergy analysis of heat pump using R744/R32 refrigerant mixture

    Directory of Open Access Journals (Sweden)

    Wang Fang

    2014-01-01

    Full Text Available An energy and exergy analysis of heat pump with blends of refrigerant mixture R744/R32 was carried out. The coefficient of performance and exergy efficiency of the system were studied with different mass fraction of R744 in the blends and different heat source temperatures. The volumetric heat capacity, condensing pressure, discharge temperature, and compression ratio were also investigated. The results indicate that at a certain concentration (15/85 by mass, the blends achieve better performance, and are superior to those of R22, the results also show that the new refrigerant mixture is an attractive option for promising alternative refrigerant.

  2. Energetic, Exergetic and Exergoeconomic Analysis of CO2 Refrigeration Systems Operating in Hot Climates

    DEFF Research Database (Denmark)

    Gullo, Paride; Elmegaard, Brian; Cortella, Giovanni

    2015-01-01

    Carbon dioxide is one of the most interesting refrigerants in terms of both environmental impact and efficiency at low outdoor temperatures. Its use in warm climates still needs for some improvements as well as some economic evaluations in order to analyse its real potential in such weather...... conditions. CO2 refrigeration system with parallel compression represents one of the solutions which have been proposed in the last few years in order to enhance the performance of a single-stage refrigeration system. The main target of this study is to compare the thermodynamic efficiency and the final cost...

  3. Modeling and investigation of refrigeration system performance with two-phase fluid injection in a scroll compressor

    Science.gov (United States)

    Gu, Rui

    Vapor compression cycles are widely used in heating, refrigerating and air-conditioning. A slight performance improvement in the components of a vapor compression cycle, such as the compressor, can play a significant role in saving energy use. However, the complexity and cost of these improvements can block their application in the market. Modifying the conventional cycle configuration can offer a less complex and less costly alternative approach. Economizing is a common modification for improving the performance of the refrigeration cycle, resulting in decreasing the work required to compress the gas per unit mass. Traditionally, economizing requires multi-stage compressors, the cost of which has restrained the scope for practical implementation. Compressors with injection ports, which can be used to inject economized refrigerant during the compression process, introduce new possibilities for economization with less cost. This work focuses on computationally investigating a refrigeration system performance with two-phase fluid injection, developing a better understanding of the impact of injected refrigerant quality on refrigeration system performance as well as evaluating the potential COP improvement that injection provides based on refrigeration system performance provided by Copeland.

  4. Electrocaloric Refrigeration for Superconductors

    Science.gov (United States)

    1977-02-01

    hardening is unspecified. The error bars on the data are for a 7 W/cmK minimum conductivity and a 14 W/cmK maximum conductivity for OFHC copper at 15 K...shortly. Cooling to as low as 0.05 K was demonstrated in CN doped RbCl . Electrocaloric refrigeration using KCl:OH has been used for ther...ym thicknesses were used along with several bonding agents: epoxy (Epibond 100-A), Corning jlass code 750 AGB devitrifying glaze, and DuPont 822 5

  5. Self-supporting refrigerated truck

    NARCIS (Netherlands)

    Beukers, A.; De Winter, S.E.E.; Brouwer, W.D.

    1997-01-01

    Self-supporting refrigerated truck comprising a floor, two side walls, a front bulkhead and a roof. The components are all constructed as sandwich panels. The connection between the rear axle construction of the refrigerated truck and the front is not provided with longitudinal beams. The function

  6. Energy optimisation of domestic refrigerators

    DEFF Research Database (Denmark)

    Jakobsen, Arne; Rasmussen, Bjarne D.

    1998-01-01

    This paper describes the main results of a research project with the objective of reducing the energy consumption of domestic refrigerators by increasing the efficiency of the refrigeration system. The improvement of the system efficiency was to be obtained by:1) Introducing continuous operation...

  7. Magnetic refrigerator for hydrogen liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, K; Kondo, T [Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Yoshioka, S; Kamiya, K; Numazawa, T [Tsukuba Magnet Laboratory, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003 (Japan)], E-mail: kmatsu@kenroku.kanazawa-u.ac.jp

    2009-02-01

    Magnetic refrigeration which is based on the magnetocaloric effect of solids has the potential to achieve high thermal efficiency for hydrogen liquefaction. We have been developing a magnetic refrigerator for hydrogen liquefaction which cools down hydrogen gas from liquid natural gas temperature and liquefies at 20 K. The magnetic liquefaction system consists of two magnetic refrigerators: Carnot magnetic refrigerator (CMR) and active magnetic regenerator (AMR) device. CMR with Carnot cycle succeeded in liquefying hydrogen at 20K. Above liquefaction temperature, a regenerative refrigeration cycle should be necessary to precool hydrogen gas, because adiabatic temperature change of magnetic material is reduced due to a large lattice specific heat of magnetic materials. We have tested an AMR device as the precooling stage. It was confirmed for the first time that AMR cycle worked around 20 K.

  8. Upper tropospheric water vapour variability over tropical latitudes ...

    Indian Academy of Sciences (India)

    Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements. Ghouse Basha ... Keywords. Water vapour; radiosonde; satellite measurements. ... National Atmospheric Research Laboratory (NARL), Department of Space, Government of India, Gadanki, PB No. 123 ...

  9. The control system of the ecological hybrid two stages refrigerating cycle

    Directory of Open Access Journals (Sweden)

    Cyklis Piotr

    2016-01-01

    Full Text Available The compression anticlockwise cycle is mostly used for refrigeration. However due to the environmental regulations, the use of classic refrigerants: F-gases is limited by international agreements. Therefore the combined compression-adsorption hybrid cycle with natural liquids: water/carbon dioxide working as the energy carriers is a promising solution. This allows to utilize the solar or waste energy for the refrigeration purpose. In this paper application of the solar collectors as the energy source for the adsorption cycle, coupled with the low temperature (LT refrigerating carbon dioxide compression cycle is shown. The control of the system is an essential issue to reduce the electric power consumption. The control of the solar heat supply and water sprayed cooling tower, for the adsorption cycle re-cooling, is presented in this paper. The designed control system and algorithm is related to the LT compression cycle, which operates according to the need of cold for the refrigeration chamber. The results of the laboratory investigations of the full system, showing the reduction of the energy consumption and maximum utilization of the solar heat for different control methods are presented.

  10. Experimental investigation of the ecological hybrid refrigeration cycle

    Directory of Open Access Journals (Sweden)

    Cyklis Piotr

    2014-09-01

    Full Text Available The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.

  11. Experimental investigation of the ecological hybrid refrigeration cycle

    Science.gov (United States)

    Cyklis, Piotr; Kantor, Ryszard; Ryncarz, Tomasz; Górski, Bogusław; Duda, Roman

    2014-09-01

    The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.

  12. Water vapour loss measurements on human skin.

    NARCIS (Netherlands)

    Valk, Petrus Gerardus Maria van der

    1984-01-01

    In this thesis, the results of a series of investigations into the barrier function of human skin are presented. In these investigations, the barrier function was assessed by water vapour loss measurements of the skin using a method based on gradient estimation.... Zie: Summary and conclusions

  13. Developments in vapour cloud explosion blast modeling

    NARCIS (Netherlands)

    Mercx, W.P.M.; Berg, A.C. van den; Hayhurst, C.J.; Robertson, N.J.; Moran, K.C.

    2000-01-01

    TNT Equivalency methods are widely used for vapour cloud explosion blast modeling. Presently, however, other types of models are available which do not have the fundamental objections TNT Equivalency models have. TNO Multi-Energy method is increasingly accepted as a more reasonable alternative to be

  14. Virucidal efficacy of hydrogen peroxide vapour disinfection

    NARCIS (Netherlands)

    Tuladhar, E.; Terpstra, P.; Koopmans, M.; Duizer, E.

    2012-01-01

    Background: Viral contamination of surfaces is thought to be important in transmission. Chemical disinfection can be an effective means of intervention, but little is known about the virucidal efficacy of hydrogen peroxide vapour (HPV) against enteric and respiratory viruses. Aim: To measure the

  15. Condensation of water vapour on moss-dominated biological soil ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 123; Issue 2 ... Condensation; water vapour; desert ecosystem; moss; biological soil crust. Abstract. Characteristics of water vapour condensation, including the onset, duration, and amount of water vapour condensation on moss-dominated biological soil crust ...

  16. estimation of precipitable water vapour in nigeria using surface ...

    African Journals Online (AJOL)

    USER

    affects the climate and weather systems through its effect on the atmospheric temperature and energy transport (Garrison, 1992; Follette et al.,. 2008). A very important measure of the atmospheric water vapour is the precipitable water vapour. (PWV). Precipitable Water Vapour (PWV) is a measure of the total amount of water ...

  17. Aerosol assisted chemical vapour deposition of gas sensitive SnO2 and Au-functionalised SnO2 nanorods via a non-catalysed vapour solid (VS) mechanism

    Science.gov (United States)

    Vallejos, Stella; Selina, Soultana; Annanouch, Fatima Ezahra; Gràcia, Isabel; Llobet, Eduard; Blackman, Chris

    2016-01-01

    Tin oxide nanorods (NRs) are vapour synthesised at relatively lower temperatures than previously reported and without the need for substrate pre-treatment, via a vapour-solid mechanism enabled using an aerosol-assisted chemical vapour deposition method. Results demonstrate that the growth of SnO2 NRs is promoted by a compression of the nucleation rate parallel to the substrate and a decrease of the energy barrier for growth perpendicular to the substrate, which are controlled via the deposition conditions. This method provides both single-step formation of the SnO2 NRs and their integration with silicon micromachined platforms, but also allows for in-situ functionalization of the NRs with gold nanoparticles via co-deposition with a gold precursor. The functional properties are demonstrated for gas sensing, with microsensors using functionalised NRs demonstrating enhanced sensing properties towards H2 compared to those based on non-functionalised NRs. PMID:27334232

  18. U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Greenblatt, Jeffery B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Young, Scott J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yang, Hung-Chia [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Long, Timothy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Beraki, Bereket [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Sarah K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pratt, Stacy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Willem, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Desroches, Louis-Benoit [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2013-04-01

    Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,820 clean survey responses were obtained from four distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 2.9(–2.5,+4.5) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

  19. U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Greenblatt, Jeffery B.; Young, Scott J.; Yang, Hung-Chia; Long, Timothy; Beraki, Bereket; Price, Sarah K.; Pratt, Stacy; Willem, Henry; Desroches, Louis-Benoit

    2013-11-14

    Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,981 clean survey responses were obtained from five distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 4.4(–2.7,+2.3) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

  20. Heat transfer and pressure drop during hydrocarbon refrigerant condensation inside a brazed plate heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Longo, Giovanni A. [University of Padova, Department of Management and Engineering, Str.lla S.Nicola 3, I-36100 Vicenza (Italy)

    2010-08-15

    This paper presents the heat transfer coefficients and pressure drop measured during HC-600a, HC-290 and HC-1270 saturated vapour condensation inside a brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature (pressure) and fluid properties are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to refrigerant mass flux and fluid properties. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 15-18 kg m{sup -2} s{sup -1}. In the forced convection condensation region the heat transfer coefficients show a 35-40% enhancement for a 60% increase of the refrigerant mass flux. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow. HC-1270 shows heat transfer coefficients 5% higher than HC-600a and 10-15% higher than HC-290, together with frictional pressure drop 20-25% lower than HC-290 and 50-66% lower than HC-600a. (author)

  1. Cryogenic refrigeration apparatus

    Science.gov (United States)

    Crunkleton, J.A.

    1992-03-31

    A technique for producing a cold environment in a refrigerant system in which input fluid from a compressor at a first temperature is introduced into an input channel of the system and is pre-cooled to a second temperature for supply to one of at least two stages of the system, and to a third temperature for supply to another stage thereof. The temperatures at such stages are reduced to fourth and fifth temperatures below the second and third temperatures, respectively. Fluid at the fourth temperature from the one stage is returned through the input channel to the compressor and fluid at the fifth temperature from the other stage is returned to the compressor through an output channel so that pre-cooling of the input fluid to the one stage occurs by regenerative cooling and counterflow cooling and pre-cooling of the input fluid to the other stage occurs primarily by counterflow cooling. 6 figs.

  2. Performance of a stationary diesel engine using vapourized ethanol as supplementary fuel

    Energy Technology Data Exchange (ETDEWEB)

    Ajav, E.A. [Ibadan Univ., Agricultural Engineering Dept., Ibadan (Nigeria); Singh, Bachchan [G.B. Pant Univ. of Agriculture and Technology, Coll. of Technology, Pantnagar (India); Bhattacharya, T.K. [G.B. Pant Univ. of Agriculture and Technology, Farm Machinery and Power Engineering Dept., Pantnagar (India)

    1998-12-31

    The modification and testing of a compression ignition engine using diesel and vapourized ethanol as fuel has been carried out. Tests on the engine fuelled with diesel only were made, and the performance evaluated to form a basis for comparison for those of ethanol-diesel dual fuelling. Modifications were made in the introduction of the ethanol and air. A carburettor was used to vaporize aqueous ethanol into the engine. The effect of preheating the intake ethanol-air mixture was also investigated. Performance was evaluated in terms of engine horsepower, brake specific fuel consumption, brake thermal efficiency, the exhaust gas temperature, lubricating oil temperature and exhaust emissions. The vapourized ethanol partially reduced diesel fuel consumption but also increased total fuel delivery. Vaporization increased power output, thermal efficiency and exhaust emission but lowered exhaust temperature and lubricating oil temperatures. (Author)

  3. High Efficiency Refrigeration Process Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A refrigeration cycle is proposed for development which can reduce compressor work and increase cooling effect, by eliminating a portion of the irreversabilities...

  4. Thermoacoustic refrigerator for space applications

    Science.gov (United States)

    Garrett, Steven L.; Adeff, Jay A.; Hofler, Thomas J.

    1993-10-01

    A new spacecraft cryocooler which uses resonant high-amplitude sound waves in inert gases to pump heat is described. The phasing of the thermoacoustic cycle is provided by thermal conduction. This 'natural' phasing allows the entire refrigerator to operate with only one moving part (the loudspeaker diaphragm). A space-qualified thermoacoustic refrigerator was flown on the Space Shuttle Discovery (STS-42) in January, 1992. It was entirely autonomous, had no sliding seals, required no lubrication, used mostly low-tolerance machined parts, and contained no expensive components. Thermoacoustics is shown to be a competitive candidate for food refrigerator/freezers and commercial/residential air conditioners. The design and performance of the Space Thermo/Acoustic Refrigerator (STAR) is described.

  5. Regulating Power from Supermarket Refrigeration

    DEFF Research Database (Denmark)

    O'Connell, Niamh; Madsen, Henrik; Pinson, Pierre

    2014-01-01

    This paper presents an analysis of the demand response capabilities of a supermarket refrigeration system, with a particular focus on the suitability for participation in the regulating power market. An ARMAX model of a supermarket refrigeration system is identified using experimental data from...... be represented in a manner that is sufficiently simple to communicate to a market operator in the form of a bid for the provision of regulating power....

  6. Interactions of fission product vapours with aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C.G.; Newland, M.S. [AEA Technology, Winfrith (United Kingdom)

    1996-12-01

    Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350{sup o}C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs.

  7. Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle

    Directory of Open Access Journals (Sweden)

    Abdellaoui Ezzaalouni Yathreb

    2017-03-01

    Full Text Available In this work, a new dual-evaporator CO2 transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2 vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.

  8. Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle

    Science.gov (United States)

    Abdellaoui, Ezzaalouni Yathreb; Kairouani, Lakdar Kairouani

    2017-03-01

    In this work, a new dual-evaporator CO2 transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2 vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.

  9. Performance characteristics of low global warming potential R134a alternative refrigerants in ejector-expansion refrigeration system

    Directory of Open Access Journals (Sweden)

    Mishra Shubham

    2016-12-01

    Full Text Available Performance assessment of ejector-expansion vapor compression refrigeration system with eco-friendly R134a alternative refrigerants (R152a, R1234yf, R600a, R600, R290, R161, R32, and propylene is presented for air-conditioning application. Ejector has been modeled by considering experimental data based correlations of component efficiencies to take care of all irreversibilities. Ejector area ratio has been optimized based on maximum coefficient of performance (COP for typical air-conditioner operating temperatures. Selected refrigerants have been compared based on area ratio, pressure lift ratio, entrainment ratio, COP, COP improvement and volumetric cooling capacity. Effects of normal boiling point and critical point on the performances have been studied as well. Using ejector as an expansion device, maximum improvement in COP is noted in R1234yf (10.1%, which reduces the COP deviation with R134a (4.5% less in basic cycle and 2.5% less in ejector cycle. Hence, R1234yf seems to be best alternative for ejector expansion system due to its mild flammability and comparable volumetric capacity and cooling COP. refrigerant R161 is superior to R134a in terms of both COP and volumetric cooling capacity, although may be restricted for low capacity application due to its flammability.

  10. Performance Improvement of R 410A Room Air Conditioner by Vapor Injection Refrigeration Cycle Using Scroll Compressor

    Science.gov (United States)

    Nakamura, Hiroo; Daisaka, Hisashi; Yokoyama, Hidenori; Nonaka, Masayuki; Saito, Kiyoshi

    The vapor injection refrigeration cycle using the scroll compressor driven by inverter was investigated to improve the performance of room air conditioner with R 410A. One injection hole was bored on a fixed scroll plate, and through this hole the vapor refrigeration is injected into two compression rooms of a scroll compressor at different time. Then the pressure change of the compression room and the performance of vapor injection refrigeration cycle are calculated. And the performance of the room air conditioner using vapor injection refrigeration cycle was measured. As the result, the cooling/heating compressor input was decreased to 7.4/3.2 % at capacity 4.0/5.9 kW, and the heating capacity at outdoor temperature -15 °C was increased to 11.9 %.

  11. COMPARISON OF CFC-114 AND HFC-236EA PERFORMANCE IN SHIPBOARD VAPOR COMPRESSION SYSTEMS

    Science.gov (United States)

    The report gives results of a comparison of the performance of two refrigerants - 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and 1,2-dichloro-tetrafluoroethane (CFC-114) - in shipboard vapor compression refrigeration systems. (NOTE: In compliance with the Montreal Protocol and Dep...

  12. Evaluating the effect of magnetocaloric properties on magnetic refrigeration performance

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

    2010-01-01

    Active magnetic regenerator (AMR) refrigerators represent an alternative to vapor compression technology that relies on the magnetocaloric effect in a solid refrigerant. Magnetocaloric materials are in development and properties are reported regularly. Recently, there has been an emphasis...... on developing materials with a high entropy change with magnetization while placing lower emphasis on the adiabatic temperature change. This work uses model magnetocaloric materials and a numerical AMR model to predict how the temperature change and entropy change with magnetization interact and how they affect...... the performance of a practical system. The distribution of the magnetocaloric effect as a function of temperature was also studied. It was found that the adiabatic temperature change in a magnetocaloric material can be more important than the isothermal entropy change for certain conditions. A material...

  13. Experimental evaluation on the use of capillary tube and thermostatic expansion valve with heat recovery hot spot water heater in air source refrigeration system

    Science.gov (United States)

    Aziz, Azridjal; Mainil, Rahmat Iman; Mainil, Afdhal Kurniawan; Saputra, Eko

    2017-01-01

    The present experimental evaluation has been carried out to investigate the use of capillary tube (CT) and thermostatic expansion valve (TEV) with heat recovery hot spot water heater (HRHSWH) in air source compression refrigeration system. CT and TEV are the two basic types of refrigerant expansion devices that most frequently used in compression refrigeration system, but the identified about HRHSWH in extant literature are limited. The HRHSWH is modified from residential refrigeration system. The heat exchanger coil as HRHSWH was bonded with the compressor discharge pipe line as counter-flow heat exchanger, then insulated and placed them into transparent acrylic box. Water from storage tank with 50L capacity is pumped using circulation pump to the HRHSWH and heating the water in storage tank. The system performance of those two expansion devices in compression refrigeration system are evaluated and compared between with or without modified using HRHSWH. Results show that refrigeration system using TEV performs better performance than CT using HRHSWH compared to standard refrigeration system (without HRHSWH). The use of TEV device in HRHSWH causes a slight decrease in compressor power 0.0198 kW (4%), where the COP increases around 20% higher than the CT device. The finding indicates that the use of HRHSWH generates free hot water for TEV and CT with temperature around 54.06°C and 55.78°C, respectively. In general, HRHSWH give better perfomance than standar refrigeration system.

  14. Economic evaluation of solar-powered triple-fluid Einstein refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    Qenawy, A.M.; El-Dib, A.W.F.; Ghoraba, M.M. [Cairo Univ., Giza (Egypt). Mechanical Power Dept., Faculty of Engineering

    2006-07-01

    The renewed interest in solar cooling systems can be attributed to rising energy prices and environmental concerns. However, the controlling factor for successful commercialization of such systems is their economic feasibility. In response, systems using solar energy are being actively developed. An alternative to vapor compression systems is the absorption refrigerator cycle which can be driven by low grade energy such as solar energy. Single pressure absorption systems are characterized by absorbing and refrigerant mediums as well as by a pressure-equalizing medium. Two cycles of this type exist, namely the ammonia-water-hydrogen (AWH) and the Einstein cycles. In the Einstein refrigeration cycle, the generator produces ammonia, the pressure-equalizing fluid that lowers the liquid butane partial pressure in the evaporator, thereby producing a cooling effect. In the proposed system, the solar collector acts as the generator. This paper investigated the economics of solar powered Einstein refrigeration system for use in the food industry or for ice production in isolated fish villages in Egypt. Such an icemaker could be used to refrigerate vaccines, meat, dairy products or vegetables. The ice can be sold as a commercial product, or used in a cooler or icebox refrigerator. Solar energy is required to produce the cooling effect in the solar powered Einstein refrigeration cycle. Although solar radiant energy is free, the equipment required to convert it to a useful cooling is not. The system ice production cost was found to be approximately 50 per cent more than other conventional refrigeration systems. Although the initial cost of the solar refrigerator was found to be relatively high, it could be an acceptable solution if this equipment is mass produced. The use of the system is essential in rural areas which do not have electric service. 12 refs., 4 figs.

  15. Development of a Battery-Free Solar Refrigerator

    Science.gov (United States)

    Ewert, Michael K.; Bergeron, David J., III

    2000-01-01

    Recent technology developments and a systems engineering design approach have led to the development of a practical battery-free solar refrigerator as a spin-off of NASA's aerospace refrigeration research. Off-grid refrigeration is a good application of solar photovoltaic (PV) power if thermal storage is incorporated and a direct connection is made between the cooling system and the PV panel. This was accomplished by integrating water as a phase-change material into a well insulated refrigerator cabinet and by developing a microprocessor based control system that allows direct connection of a PV panel to a variable speed compressor. This second innovation also allowed peak power-point tracking from the PV panel and elimination of batteries from the system. First a laboratory unit was developed to prove the concept and then a commercial unit was produced and deployed in a field test. The laboratory unit was used to test many different configurations including thermoelectric, Stirling and vapor compression cooling systems. The final configuration used a vapor compression cooling cycle, vacuum insulation, a passive condenser, an integral evaporator/ thermal storage tank, two 77 watt PV panels and the novel controller mentioned above. The system's only moving part was the variable speed BD35 compressor made by Danfoss. The 365 liter cabinet stayed cold with as little as 274 watt-hours per day average PV power. Battery-free testing was conducted for several months with very good results. The amount of thermal storage, size of compressor and power of PV panels connected can all be adjusted to optimize the design for a given application and climate. In the commercial unit, the high cost of the vacuum insulated refrigerator cabinet and the stainless steel thermal storage tank were addressed in an effort to make the technology commercially viable. This unit started with a 142 liter, mass-produced chest freezer cabinet that had the evaporator integrated into its inner walls

  16. A review of pulse tube refrigeration

    Science.gov (United States)

    Radebaugh, Ray

    1990-01-01

    This paper reviews the development of the three types of pulse tube refrigerators: basic, resonant, and orifice types. The principles of operation are given. It is shown that the pulse tube refrigerator is a variation of the Stirling-cycle refrigerator, where the moving displacer is substituted by a heat transfer mechanism or by an orifice to bring about the proper phase shifts between pressure and mass flow rate. A harmonic analysis with phasors is described which gives reasonable results for the refrigeration power, yet is simple enough to make clear the processes which give rise to the refrigeration. The efficiency and refrigeration power are compared with those of other refrigeration cycles. A brief review is given of the research being done at various laboratories on both one- and two-stage pulse tubes. A preliminary assessment of the role of pulse tube refrigerators is discussed.

  17. REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    Science.gov (United States)

    Large refrigeration systems are found in several applications including supermarkets, cold storage warehouses, and industrial processes. The sizes of these systems are a contributing factor to their problems of high refrigerant leak rates because of the thousands of connections, ...

  18. Refrigeration system having dual suction port compressor

    Science.gov (United States)

    Wu, Guolian

    2016-01-05

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

  19. 16 CFR Appendix A2 to Part 305 - Refrigerators and Refrigerators-Freezers With Manual Defrost

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Refrigerators and Refrigerators-Freezers With Manual Defrost A2 Appendix A2 to Part 305 Commercial Practices FEDERAL TRADE COMMISSION... Refrigerators-Freezers With Manual Defrost Range Information Manufacturer's Rated Total Refrigerated Volume in...

  20. Load forecasting for supermarket refrigeration

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Aalborg Nielsen, Henrik

    This report presents a study of models for forecasting the load for supermarket refrigeration. The data used for building the forecasting models consists of load measurements, local climate measurements and weather forecasts. The load measurements are from a supermarket located in a village...... in Denmark. The load for refrigeration is the sum of all cabinets in the supermarket, both low and medium temperature cabinets, and spans a period of one year. As input to the forecasting models the ambient temperature observed near the supermarket together with weather forecasts are used. Every hour...... the hourly load for refrigeration for the following 42 hours is forecasted. The forecast models are adaptive linear time-series models which are fitted with a computationally efficient recursive least squares scheme. The dynamic relations between the inputs and the load is modeled by simple transfer...

  1. Variability of water vapour in the Arctic stratosphere

    Science.gov (United States)

    Thölix, Laura; Backman, Leif; Kivi, Rigel; Karpechko, Alexey Yu.

    2016-04-01

    This study evaluates the stratospheric water vapour distribution and variability in the Arctic. A FinROSE chemistry transport model simulation covering the years 1990-2014 is compared to observations (satellite and frost point hygrometer soundings), and the sources of stratospheric water vapour are studied. In the simulations, the Arctic water vapour shows decadal variability with a magnitude of 0.8 ppm. Both observations and the simulations show an increase in the water vapour concentration in the Arctic stratosphere after the year 2006, but around 2012 the concentration started to decrease. Model calculations suggest that this increase in water vapour is mostly explained by transport-related processes, while the photochemically produced water vapour plays a relatively smaller role. The increase in water vapour in the presence of the low winter temperatures in the Arctic stratosphere led to more frequent occurrence of ice polar stratospheric clouds (PSCs) in the Arctic vortex. We perform a case study of ice PSC formation focusing on January 2010 when the polar vortex was unusually cold and allowed large-scale formation of PSCs. At the same time a large-scale persistent dehydration was observed. Ice PSCs and dehydration observed at Sodankylä with accurate water vapour soundings in January and February 2010 during the LAPBIAT (Lapland Atmosphere-Biosphere facility) atmospheric measurement campaign were well reproduced by the model. In particular, both the observed and simulated decrease in water vapour in the dehydration layer was up to 1.5 ppm.

  2. Water vapour measurements during POLINAT 1

    Energy Technology Data Exchange (ETDEWEB)

    Ovarlez, J.; Ovarlez, H. [Centre National de la Recherche Scientifique, 91 - Palaiseau (France). Lab. de Meteorologie Dynamique

    1997-12-31

    The POLINAT (POLlution from aircraft emissions In the North ATlantic flight corridor)1 experiment has been performed within the framework of the Environment Programme of the Commission of the European Community. It was devoted to the study of the pollution from aircraft in the North Atlantic flight corridor, in order to investigate the impact of pollutants emitted by aircraft on the concentrations of ozone and other trace gases in the upper troposphere and lower stratosphere. For that experiment the water vapour content was measured with a frost-point hygrometer on board of the DLR Falcon research aircraft. This instrument is described, and some selected results are given. (author) 19 refs.

  3. Wheel-type magnetic refrigerator

    Science.gov (United States)

    Barclay, J.A.

    1982-01-20

    The disclosure is directed to a wheel-type magnetic refrigerator capable of cooling over a large temperature range. Ferromagnetic or paramagnetic porous materials are layered circumferentially according to their Curie temperature. The innermost layer has the lowest Curie temperature and the outermost layer has the highest Curie temperature. The wheel is rotated through a magnetic field perpendicular to the axis of the wheel and parallel to its direction of rotation. A fluid is pumped through portions of the layers using inner and outer manifolds to achieve refrigeration of a thermal load.

  4. Load forecasting of supermarket refrigeration

    DEFF Research Database (Denmark)

    Rasmussen, Lisa Buth; Bacher, Peder; Madsen, Henrik

    2016-01-01

    This paper presents a novel study of models for forecasting the electrical load for supermarket refrigeration. The data used for building the models consists of load measurements, local climate measurements and weather forecasts. The load measurements are from a supermarket located in a village...... in Denmark. Every hour the hourly electrical load for refrigeration is forecasted for the following 42 h. The forecast models are adaptive linear time series models. The model has two regimes; one for opening hours and one for closing hours, this is modeled by a regime switching model and two different...

  5. Solar Refrigerators Store Life-Saving Vaccines

    Science.gov (United States)

    2014-01-01

    Former Johnson Space Center engineer David Bergeron used his experience on the Advanced Refrigeration Technology Team to found SunDanzer Refrigeration Inc., a company specializing in solar-powered refrigerators. The company has created a battery-free unit that provides safe storage for vaccines in rural and remote areas around the world.

  6. 49 CFR 173.174 - Refrigerating machines.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Refrigerating machines. A refrigerating machine assembled for shipment and containing 7 kg (15 pounds) or less...

  7. 46 CFR 154.702 - Refrigerated carriage.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Refrigerated carriage. 154.702 Section 154.702 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS... Pressure and Temperature Control § 154.702 Refrigerated carriage. (a) Each refrigeration system must: (1...

  8. Method and apparatus for desuperheating refrigerant

    Energy Technology Data Exchange (ETDEWEB)

    Zess, James A. (Kelso, WA); Drost, M. Kevin (Richland, WA); Call, Charles J. (Richland, WA)

    1997-01-01

    The present invention is an apparatus and method for de-superheating a primary refrigerant leaving a compressor wherein a secondary refrigerant is used between the primary refrigerant to be de-superheated. Reject heat is advantageously used for heat reclaim.

  9. Refrigeration Cycle Design for Refrigerant Mixtures by Molecular Simulation

    Czech Academy of Sciences Publication Activity Database

    Smith, W.R.; Francová, Magda; Kowalski, M.; Nezbeda, Ivo

    2010-01-01

    Roč. 75, č. 4 (2010), s. 383-391 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400720710 Grant - others:NSERC(CA) OGP1041 Institutional research plan: CEZ:AV0Z40720504 Keywords : refrigerants * molecular simulations * vapor–liquid equilibrium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.853, year: 2010

  10. Simulation of inviscid compressible multi-phase flow with condensation

    NARCIS (Netherlands)

    Kelleners, P.H.

    2003-01-01

    Condensation of vapours in rapid expansions of compressible gases is investigated. In the case of high temperature gradients the condensation will start at conditions well away from thermodynamic equilibrium of the fluid. In those cases homogeneous condensation is dominant over heterogeneous

  11. Water vapour variability and trends in the Arctic stratosphere

    Science.gov (United States)

    Thölix, Laura; Kivi, Rigel; Backman, Leif; Karpechko, Alexey

    2014-05-01

    Water vapour in the upper troposphere-lower stratosphere (UTLS) is a radiatively and chemically important trace gas. Stratospheric water vapour also affects ozone chemistry through odd-hydrogen chemistry and formation of polar stratospheric clouds (PSC). Both transport and chemistry contribute to the extratropical lower stratospheric water vapour distribution and trends. The main sources of stratospheric water vapour are intrusion through the tropical tropopause and production from oxidation of methane. Accurate observations of UTLS water vapour are difficult to obtain due to the strong gradient in the water vapour profile over the tropopause. However, modelling the stratospheric water vapour distribution is challenging and accurate measurements are needed for model validation. Trends in Arctic water vapour will be analysed and explained in terms of contribution from different processes (transport and chemistry), using observations and chemistry transport model (CTM) simulations. Accurate water vapour soundings from Sodankylä will be used to study water vapour within the Arctic polar vortex, including process studies on formation of PSCs and dehydration. Water vapour profiles measured during the LAPBIAT atmospheric sounding campaign in Sodankylä in January 2010 indicated formation of ice clouds and dehydration. Effects on ozone chemistry will also be studied. Global middle atmospheric simulations have been performed with the FinROSE-ctm using ERA-Interim winds and temperatures. The FinROSE-ctm is a global middle atmosphere model that produces the distribution of 30 long-lived species and tracers and 14 short-lived species. The chemistry describes around 110 gas phase reactions, 37 photodissociation processes and the main heterogeneous reactions related to aerosols and polar stratospheric clouds.

  12. Performance of Oil-Injected Scroll Compressors for Helium Refrigerators

    Science.gov (United States)

    Shiibayashi, Masao; Izunaga, Yasushi; Sado, Shintaro

    In recent years there arises growing demand of helium liquefaction refrigerators for the magnetic resonance imaging systems, magnetically levitated vehicles and other systems using superconducting magnet. From this background, a small size, scroll type of hermetic helium compressor capable of compressing helium gas to the pressure ratio of 20 in a single stage is developed. Main features of this compressor are as follows. 1) Discharge capacity can be varied from 7 to 20 Nm3/h by changing driving motor frequency from 30 to 80 Hz. 2) The overall adiabatic efficiency showed 72%∼79% under the pressure ratio range of 11∼20 at 60 Hz using oil injection cooling device.

  13. High Efficiency, Low Emission Refrigeration System

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Brian A [ORNL; Sharma, Vishaldeep [ORNL

    2016-08-01

    Supermarket refrigeration systems account for approximately 50% of supermarket energy use, placing this class of equipment among the highest energy consumers in the commercial building domain. In addition, the commonly used refrigeration system in supermarket applications is the multiplex direct expansion (DX) system, which is prone to refrigerant leaks due to its long lengths of refrigerant piping. This leakage reduces the efficiency of the system and increases the impact of the system on the environment. The high Global Warming Potential (GWP) of the hydrofluorocarbon (HFC) refrigerants commonly used in these systems, coupled with the large refrigerant charge and the high refrigerant leakage rates leads to significant direct emissions of greenhouse gases into the atmosphere. Methods for reducing refrigerant leakage and energy consumption are available, but underutilized. Further work needs to be done to reduce costs of advanced system designs to improve market utilization. In addition, refrigeration system retrofits that result in reduced energy consumption are needed since the majority of applications address retrofits rather than new stores. The retrofit market is also of most concern since it involves large-volume refrigerant systems with high leak rates. Finally, alternative refrigerants for new and retrofit applications are needed to reduce emissions and reduce the impact on the environment. The objective of this Collaborative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory and Hill Phoenix is to develop a supermarket refrigeration system that reduces greenhouse gas emissions and has 25 to 30 percent lower energy consumption than existing systems. The outcomes of this project will include the design of a low emission, high efficiency commercial refrigeration system suitable for use in current U.S. supermarkets. In addition, a prototype low emission, high efficiency supermarket refrigeration system will be produced for

  14. Magnetic refrigerator for hydrogen liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, T [National Institute for Materials Science, Tsukuba (Japan); Kamlya, K. [Japan Atomic Energy Agency, Naka (Japan); Utaki, T. [Osaka University, Osaka (Japan); Matsumoto, K. [Kanazawa University, Kanazawa (Japan)

    2013-06-15

    This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. Liquid hydrogen is in cryogenic temperatures and therefore high efficient liquefaction method must be studied. Magnetic refrigeration which uses the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency > 50 %, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system > 80 % liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12 K for 1.8 T of the magnetic field and 6 second of the cycle. By using the simulation, we estimate the total efficiency of the hydrogen liquefaction plant for 10 kg/day. A FOM of 0.47 is obtained in the magnetic refrigeration system operation temperature between 20 K and 77 K including LN2 work input.

  15. Beam-profile monitor using a sodium-vapour

    CERN Multimedia

    1972-01-01

    Beam-profile monitor using a sodium-vapour curtain at 45 degrees to the ISR beam in Ring I (sodium generator is in white cylinder just left of centre). Electrons produced by ionization of the sodium vapour give an image of the beam on a fluorescent screen that is observed by a TV camera (at upper right).

  16. Keeping Cool With Solar-Powered Refrigeration

    Science.gov (United States)

    2003-01-01

    In the midst of developing battery-free, solar-powered refrigeration and air conditioning systems for habitats in space, David Bergeron, the team leader for NASA's Advanced Refrigerator Technology Team at Johnson Space Center, acknowledged the need for a comparable solar refrigerator that could operate in conjunction with the simple lighting systems already in place on Earth. Bergeron, a 20-year veteran in the aerospace industry, founded the company Solus Refrigeration, Inc., in 1999 to take the patented advanced refrigeration technology he co-developed with his teammate, Johnson engineer Michael Ewert, to commercial markets. Now known as SunDanzer Refrigeration, Inc., Bergeron's company is producing battery-free, photovoltaic (PV) refrigeration systems under license to NASA, and selling them globally.

  17. A LiBr-H2O Absorption Refrigerator Incorporating a Thermally Activated Solution Pumping Mechanism

    Directory of Open Access Journals (Sweden)

    Ian W. Eames

    2017-02-01

    Full Text Available This paper provides an illustrated description of a proposed LiBr-H2O vapour absorption refrigerator which uses a thermally activated solution pumping mechanism that combines controlled variations in generator vapour pressure with changes it produces in static-head pressure difference to circulate the absorbent solution between the generator and absorber vessels. The proposed system is different and potentially more efficient than a bubble pump system previously proposed and avoids the need for an electrically powered circulation pump found in most conventional LiBr absorption refrigerators. The paper goes on to provide a sample set of calculations that show that the coefficient of performance values of the proposed cycle are similar to those found for conventional cycles. The theoretical results compare favourably with some preliminary experimental results, which are also presented for the first time in this paper. The paper ends by proposing an outline design for an innovative steam valve, which is a key component needed to control the solution pumping mechanism.

  18. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2012-09-12

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

  19. When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study.

    Science.gov (United States)

    Haidari, Leila A; Brown, Shawn T; Wedlock, Patrick; Connor, Diana L; Spiker, Marie; Lee, Bruce Y

    2017-04-19

    Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as "electric refrigerators") at different locations in the supply chain under various circumstances. At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar refrigerator prices. Copyright © 2017. Published

  20. Compression embedding

    Science.gov (United States)

    Sandford, M.T. II; Handel, T.G.; Bradley, J.N.

    1998-07-07

    A method and apparatus for embedding auxiliary information into the digital representation of host data created by a lossy compression technique and a method and apparatus for constructing auxiliary data from the correspondence between values in a digital key-pair table with integer index values existing in a representation of host data created by a lossy compression technique are disclosed. The methods apply to data compressed with algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as ordered sequences of blocks containing integer indices having redundancy and uncertainty of value by one unit, allowing indices which are adjacent in value to be manipulated to encode auxiliary data. Also included is a method to improve the efficiency of lossy compression algorithms by embedding white noise into the integer indices. Lossy compression methods use loss-less compression to reduce to the final size the intermediate representation as indices. The efficiency of the loss-less compression, known also as entropy coding compression, is increased by manipulating the indices at the intermediate stage. Manipulation of the intermediate representation improves lossy compression performance by 1 to 10%. 21 figs.

  1. Dilution Refrigerator for Nuclear Refrigeration and Cryogenic Thermometry Studies

    Science.gov (United States)

    Nakagawa, Hisashi; Hata, Tohru

    2014-07-01

    This study explores the design and construction of an ultra-low temperature facility in order to realize the Provisional low-temperature scale from 0.9 mK to 1 K (PLTS-2000) in Japan, to disseminate its use through calibration services, and to study thermometry at low temperatures below 1 K. To this end, a dilution refrigerator was constructed in-house that has four sintered silver discrete heat exchangers for use as a precooling stage of a copper nuclear demagnetization stage. A melting curve thermometer attached to the mixing chamber flange could be cooled continuously to 4.0 mK using the refrigerator. The dependence of minimum temperatures on circulation rates can be explained by the calculation of Frossati's formula based on a perfect continuous counterflow heat exchanger model, assuming that the Kapitza resistance has a temperature dependence. Residual heat leakage to the mixing chamber was estimated to be around 86 nW. A nuclear demagnetization cryostat with a nuclear stage containing an effective amount of copper (51 mol in a 9 T magnetic field) is under construction, and we will presently start to work toward the realization of the PLTS-2000. In this article, the design and performance of the dilution refrigerator are reported.

  2. Study on the Materials for Compressor and Reliability of Refrigeration Circuit in Refrigerator with R134a Refrigerant

    Science.gov (United States)

    Komatsubara, Takeo; Sunaga, Takasi; Takahasi, Yasuki

    R134a was selected as the alternative refrigerant for R12 because of the similar thermodynamic properties with R12. But refrigeration oil for R12 couldn't be used for R134a because of the immiscibility with R134a. To solve this problem we researched miscible oil with R134a and selected polyol ester oil (POE) as refrigeration oil. But we found sludge deposition into capillary tube after life test of refrigerator with POE and detected metal soap, decomposed oil and alkaline ions by analysis of sludge. This results was proof of phenomena like oil degradation, precipitation of process materials and wear of compressor. Therefore we improved stability and lubricity of POE, reevaluated process materials and contaminations in refrigerating circuit. In this paper we discuss newly developed these technologies and evaluation results of it by life test of refrigerator.

  3. When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study☆

    Science.gov (United States)

    Haidari, Leila A.; Brown, Shawn T.; Wedlock, Patrick; Connor, Diana L.; Spiker, Marie; Lee, Bruce Y.

    2017-01-01

    Background Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Methods Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as “electric refrigerators”) at different locations in the supply chain under various circumstances. Results At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Conclusion Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar

  4. Load forecasting of supermarket refrigeration

    DEFF Research Database (Denmark)

    Rasmussen, Lisa Buth; Bacher, Peder; Madsen, Henrik

    2016-01-01

    This paper presents a novel study of models for forecasting the electrical load for supermarket refrigeration. The data used for building the models consists of load measurements, local climate measurements and weather forecasts. The load measurements are from a supermarket located in a village...... in Denmark. Every hour the hourly electrical load for refrigeration is forecasted for the following 42 h. The forecast models are adaptive linear time series models. The model has two regimes; one for opening hours and one for closing hours, this is modeled by a regime switching model and two different...... methods for predicting the regimes are tested. The dynamic relation between the weather and the load is modeled by simple transfer functions and the non-linearities are described using spline functions. The results are thoroughly evaluated and it is shown that the spline functions are suitable...

  5. CO2 as a refrigerant

    CERN Document Server

    2014-01-01

    A first edition, the IIR guide “CO2 as a Refrigerant” highlights the application of carbon dioxide in supermarkets, industrial freezers, refrigerated transport, and cold stores as well as ice rinks, chillers, air conditioning systems, data centers and heat pumps. This guide is for design and development engineers needing instruction and inspiration as well as non-technical experts seeking background information on a specific topic. Written by Dr A.B. Pearson, a well-known expert in the field who has considerable experience in the use of CO2 as a refrigerant. Main topics: Thermophysical properties of CO2 – Exposure to CO2, safety precautions – CO2 Plant Design – CO2 applications – Future prospects – Standards and regulations – Bibliography.

  6. Suction muffler for refrigeration compressor

    Science.gov (United States)

    Nelson, Richard T.; Middleton, Marc G.

    1983-01-01

    A hermetic refrigeration compressor includes a suction muffler formed from two pieces of plastic material mounted on the cylinder housing. One piece is cylindrical in shape with an end wall having an aperture for receiving a suction tube connected to the cylinder head. The other piece fits over and covers the other end of the cylindrical piece, and includes a flaring entrance horn which extends toward the return line on the sidewall of the compressor shell.

  7. Carbon Dioxide in Supermarket Refrigeration

    OpenAIRE

    Sawalha, Samer

    2008-01-01

    This thesis theoretically and experimentally investigates different aspects of the application of CO2 in supermarket refrigeration. Theoretical analysis has been performed using computer simulation models developed to simulate CO2 indirect, NH3/CO2 cascade, CO2 trans-critical and direct expansion (DX) R404A systems. The models supported the selection of the CO2 system solutions to be tested experimentally and facilitated the design of NH3/CO2 cascade and trans-critical systems test rigs. Perf...

  8. Medical cannabis use in Canada: vapourization and modes of delivery

    Directory of Open Access Journals (Sweden)

    Samantha Shiplo

    2016-10-01

    Full Text Available Abstract Background The mode of medical cannabis delivery—whether cannabis is smoked, vapourized, or consumed orally—may have important implications for its therapeutic efficacy and health risks. However, there is very little evidence on current patterns of use among Canadian medical cannabis users, particularly with respect to modes of delivery. The current study examined modes of medical cannabis delivery following regulatory changes in 2014 governing how Canadians access medical cannabis. Methods A total of 364 approved adult Canadian medical cannabis users completed an online cross-sectional survey between April and June 2015. The survey examined patterns of medical cannabis use, modes of delivery used, and reasons for use. Participants were recruited through a convenience sample from nine Health Canada licensed producers. Results Using a vapourizer was the most popular mode of delivery for medical cannabis (53 %, followed by smoking a joint (47 %. The main reason for using a vapourizer was to reduce negative health consequences associated with smoking. A majority of current vapourizer users reported using a portable vapourizer (67.2 %, followed by a stationary vapourizer (41.7 %, and an e-cigarette or vape pen (19.3 %. Current use of a vapourizer was associated with fewer respiratory symptoms (AOR = 1.28, 95 % CI 1.05–1.56, p = 0.01. Conclusions The findings suggest an increase in the popularity of vapourizers as the primary mode of delivery among approved medical users. Using vapourizers has the potential to prevent some of the adverse respiratory health consequences associated with smoking and may serve as an effective harm reduction method. Monitoring implications of such current and future changes to medical cannabis regulations may be beneficial to policymakers.

  9. Grey-box Modeling for System Identification of Household Refrigerators: a Step Toward Smart Appliances

    DEFF Research Database (Denmark)

    Costanzo, Giuseppe Tommaso; Sossan, Fabrizio; Marinelli, Mattia

    2013-01-01

    This paper presents the grey-box modeling of a vapor-compression refrigeration system for residential applications based on maximum likelihood estimation of parameters in stochastic differential equations. Models obtained are useful in the view of controlling refrigerators as flexible consumption...... units, which operation can be shifted within temperature and operational constraints. Even if the refrigerators are not intended to be used as smart loads, validated models are useful in predicting units consumption. This information can increase the optimality of the management of other flexible units......, such as heat pumps for space heating, in order to smooth the load factor during peak hours, enhance reliability and efficiency in power networks and reduce operational costs....

  10. Application of waste heat powered absorption refrigeration system to the LNG recovery process

    Energy Technology Data Exchange (ETDEWEB)

    Kalinowski, Paul; Hwang, Yunho; Radermacher, Reinhard [Center for Environmental Energy Engineering, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States); Al Hashimi, Saleh; Rodgers, Peter [The Petroleum Institute, Abu Dhabi (United Arab Emirates)

    2009-06-15

    The recovery process of the liquefied natural gas requires low temperature cooling, which is typically provided by the vapor compression refrigeration systems. The usage of an absorption refrigeration system powered by waste heat from the electric power generating gas turbine could provide the necessary cooling at reduced overall energy consumption. In this study, a potential replacement of propane chillers with absorption refrigeration systems was theoretically analyzed. From the analysis, it was found that recovering waste heat from a 9 megawatts (MW) electricity generation process could provide 5.2 MW waste heat produced additional cooling to the LNG plant and save 1.9 MW of electricity consumption. Application of the integrated cooling, heating, and power is an excellent energy saving option for the oil and gas industry. (author)

  11. Modeling of a heat pump charged with a non-azeotropic refrigerant mixture

    Science.gov (United States)

    Domanski, P.

    1986-01-01

    An analysis of the vapor compression cycle and the main components of an air-to-air heat pump charged with a binary non-azeotropic mixture has been performed for steady-state operation. The general heat pump simulation model HPBI has been formulated which is based on independent, analytical models of system components and the logic linking them together. The logic of the program requires an iterative solution of refrigerant pressure and enthalpy balances, and refrigerant mixture and individual mixture component mass inventories. The modeling effort emphasis was on the local thermodynamic phenomena which were described by fundamental heat transfer equations and equation of state relationships among material properties. In the compressor model several refrigerant locations were identified and the processes taking place between these locations accounted for all significant heat and pressure losses.

  12. Energy Efficient Commercial Refrigeration with Carbon Dioxide Refrigerant and Scroll Expanders

    Energy Technology Data Exchange (ETDEWEB)

    Dieckmann, John [TIAX LLC, Lexington, MA (United States)

    2013-04-04

    Current supermarket refrigeration systems are built around conventional fluorocarbon refrigerants – HFC-134a and the HFC blends R-507 and R404A, which replaced the CFC refrigerants, R-12 and R-502, respectively, used prior to the Montreal Protocol phase out of ozone depleting substances. While the HFC refrigerants are non-ozone depleting, they are strong greenhouse gases, so there has been continued interest in replacing them, particularly in applications with above average refrigerant leakage. Large supermarket refrigeration systems have proven to be particularly difficult to maintain in a leak-tight condition. Refrigerant charge losses of 15% of total charge per year are the norm, making the global warming impact of refrigerant emissions comparable to that associated with the energy consumption of these systems.

  13. High-Performance, Low Environmental Impact Refrigerants

    Science.gov (United States)

    McCullough, E. T.; Dhooge, P. M.; Glass, S. M.; Nimitz, J. S.

    2001-01-01

    Refrigerants used in process and facilities systems in the US include R-12, R-22, R-123, R-134a, R-404A, R-410A, R-500, and R-502. All but R-134a, R-404A, and R-410A contain ozone-depleting substances that will be phased out under the Montreal Protocol. Some of the substitutes do not perform as well as the refrigerants they are replacing, require new equipment, and have relatively high global warming potentials (GWPs). New refrigerants are needed that addresses environmental, safety, and performance issues simultaneously. In efforts sponsored by Ikon Corporation, NASA Kennedy Space Center (KSC), and the US Environmental Protection Agency (EPA), ETEC has developed and tested a new class of refrigerants, the Ikon (registered) refrigerants, based on iodofluorocarbons (IFCs). These refrigerants are nonflammable, have essentially zero ozone-depletion potential (ODP), low GWP, high performance (energy efficiency and capacity), and can be dropped into much existing equipment.

  14. HeREF-2003 : Helium Refrigeration Techniques

    CERN Multimedia

    2003-01-01

    CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF ...

  15. HeREF-2003: Helium Refrigeration Techniques

    CERN Multimedia

    2003-01-01

    CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

  16. Adsorption refrigeration technology theory and application

    CERN Document Server

    Wang, Ruzhu; Wu, Jingyi

    2014-01-01

    Gives readers a detailed understanding of adsorption refrigeration technology, with a focus on practical applications and environmental concerns Systematically covering the technology of adsorption refrigeration, this book provides readers with a technical understanding of the topic as well as detailed information on the state-of-the-art from leading researchers in the field. Introducing readers to background on the development of adsorption refrigeration, the authors also cover the development of adsorbents, various thermodynamic theories, the design of adsorption systems and adsorption refri

  17. Refrigeration for a supraconducting 1000 MVA generator

    Energy Technology Data Exchange (ETDEWEB)

    Nienaber, U.; Stephan, A.; Weber, J.

    1985-01-01

    The author discusses the requirements made on the refrigerating system for high-capacity turbogenerators. He presents the block diagram of the refrigerating system, explains the associated tasks, demonstrates the selected process by means of the process flow diagram of the He refrigerator system, describes the major components like loop compressor with oil separator, gas and oil flow, cold box, expansion turbine and process control. (HAG).

  18. Energy efficient for refrigeration and air conditioning

    OpenAIRE

    Abdeen Mustafa Omer

    2015-01-01

    Over the years, all parts of a commercial refrigerator, such as the compressor, heat exchangers, refrigerant, and packaging, have been improved considerably due to the extensive research and development efforts carried out by academia and industry. However, the achieved and anticipated improvement in conventional refrigeration technology are incremental since this technology is already nearing its fundamentals limit of energy efficiency is described is ‘magnetic refrigeration’ which is an evo...

  19. Piezoelectric driven thermo-acoustic refrigerator

    Science.gov (United States)

    Chinn, D. G.; Nouh, M.; Aldraihem, O.; Baz, A.

    2011-03-01

    Thermoacoustic refrigeration is an emerging refrigeration technology which does not rely for in its operation on the use of any moving parts or harmful refrigerants. This technology uses acoustic waves to pump heat across a temperature gradient. The vast majority of thermoacoustic refrigerators to date have used electromagnetic loudspeakers to generate the acoustic input. In this paper, the design, construction, operation, and modeling of a piezoelectric-driven thermoacoustic refrigerator are detailed. This refrigerator demonstrates the effectiveness of piezoelectric actuation in moving 0.3 W of heat across an 18 degree C temperature difference with an input power of 7.6 W. The performance characteristics of this class of thermoacoustic-piezoelectric refrigerator are modeled using DeltaEC software and the predictions are validated experimentally. The obtained results confirm the validity of the developed model. Furthermore, the potential of piezoelectric actuation as effective means for driving thermoacoustic refrigerators is demonstrated as compared to the conventional electromagnetic loudspeakers which are heavy and require high actuation energy. The developed theoretical and experimental tools can serve as invaluable means for the design and testing of other piezoelectric driven thermoacoustic refrigerator configurations.

  20. Modelling the absorption refrigeration cycle using partially miscible working fluids by group contribution methods

    Science.gov (United States)

    Larkeche, O.; Meniai, A.-H.; Cachot, T.

    2012-06-01

    The present study concerns the cycle performance modelling of a particular configuration of an absorption refrigeration machine based on phase separation as well as development of a strategy for computer aided design of absorbents. The model uses predictive methods based on the group contribution concept for the computation of the thermodynamic phase equilibria involved such as liquid-liquid and vapour-liquid as well as enthalpy-concentration diagrams. The proposed absorbents computer-aided design strategy is based on the exploration of a number of structural group combinations obtained from a selected set of functional groups, according to the chemistry laws. The model was tested on four different absorbent-refrigerant pairs reported in the literature, namely (benzyl ethyl amine-glycerol), (water-hexanoic acid), (water-2-hexanone) and (water-ethyl propionate) as well as on pairs where the absorbent compound is generated by the proposed absorbent design strategy and the refrigerant is water. The results show that quite good values of the coefficient of performance (COP) can be obtained, indicating that this cycle configuration is promising and energetically efficient, mainly due to hardware savings, i.e. absence of condenser. However, other working fluid combinations have to be tested using the proposed model.

  1. Refrigerant charge management in a heat pump water heater

    Science.gov (United States)

    Chen, Jie; Hampton, Justin W.

    2016-07-05

    Heat pumps that heat or cool a space and that also heat water, refrigerant management systems for such heat pumps, and methods of managing refrigerant charge. Various embodiments remove idle refrigerant from a heat exchanger that is not needed for transferring heat by opening a refrigerant recovery valve and delivering the idle refrigerant from the heat exchanger to an inlet port on the compressor. The heat exchanger can be isolated by closing an electronic expansion valve, actuating a refrigerant management valve, or both. Refrigerant charge can be controlled by controlling how much refrigerant is drawn from the heat exchanger, by letting some refrigerant back into the heat exchanger, or both. Heat pumps can be operated in different modes of operation, and various components can be interconnected with refrigerant conduit. Some embodiments deliver refrigerant gas to the heat exchanger and drive liquid refrigerant out prior to isolating the heat exchanger.

  2. Filtering of oil vapours. Oelfrei lautet die Parole

    Energy Technology Data Exchange (ETDEWEB)

    Goehringer, P.

    1992-07-20

    Air filters are used for removing oil vapours and protecing the respiratory tract. There are centralized solutions such as cyclones side by side with individually mounted filters with casings. (orig.)

  3. Development of green vapour corrosion inhibitor

    Science.gov (United States)

    Asmara, Y. P.; Suraj, V.; Siregar, J. P.; Kurniawan, T.; Bachtiar, D.; Mohamed, N. M. Z. N.

    2017-10-01

    Corrosion control using inhibitor is an effective method to protect carbon steel from corrosion. Due to environmental toxicity of chemical inorganic corrosion inhibitors (synthetic), green inhibitors are potentially to develop. In atmospheric conditions, green vapour corrosion inhibitors are the best solutions to replace the uses of inorganic corrosion inhibitors. This research used chemical acid extraction from the key lime (citrus aurantiifolia) leaves and seeds. They are used as the main ingredients to produce this effective green corrosion inhibitor. The experiments investigated effects of corrosion inhibition on corrosion rate of low carbon steel in 3% NaCl solution using both fog salt chamber and electrochemical cell. Using salt fog chamber to represent atmospheric conditions, and corrosion rates are evaluated visually and calculated using weight loss methods. Corrosion rate on electrochemical cell were calculated using linear polarization resistance (LPR) methods. All of the experiments were set in natural conditions at pH 7. Using weight loss for three days exposure time, the efficiency of the inhibitor reached 82.39%.

  4. Vapour galvanizing (Sherardizing) of copper with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wortelen, Dietbert; Bracht, Hartmut [Westfaelische Wilhelms-Universitaet Muenster (Germany); Natrup, Frank; Graf, Wolfram [Bodycote Waermebehandlung GmbH, Sprockhoevel (Germany)

    2010-07-01

    Using a vapour galvanizing technique called Sherardizing we investigated the growth kinetics and coefficients of zinc copper phases. For this purpose polished (OFHC)-copper plates and zinc powder have been sealed in quartz ampoules under inert gas atmospheres and annealed at a temperature range between 300 and 410 C. In order to study the coating thickness and the phase composition, cross sections were prepared, which have been analyzed by means of optical microscopy and scanning electron microscopy. We were able to demonstrate that the coating thickness is a function of the parabolic time law and that the formed coatings are composed of two layers referring to the ordered {beta}-CuZn and {gamma}-Cu{sub 5}Zn{sub 8}-phases. To enhance the coating quality, small amounts of ZnCl{sub 2} were added to the zinc powder. It was observed that the coating thickness decreased with increasing ZnCl{sub 2}. Experiments with variable Ar-pressure demonstrated a reduced coating growth with increasing pressures. Further measurements with ZnCl{sub 2} were performed to check whether an electrochemical mechanism is involved in the coating process.

  5. Landmine Detection Technologies to TraceExplosive Vapour Detection Techniques

    OpenAIRE

    J. C. Kapoor; G. K. Kannan

    2007-01-01

    Large quantity of explosive is manufactured worldwide for use in various types of ammunition,arms, and mines, and used in armed conflicts. During manufacturing and usage of the explosiveequipment, some of the explosive residues are released into the environment in the form ofcontaminated effluents, unburnt explosives fumes and vapours. Limited but uncontrolledcontinuous release of trace vapours also takes place when explosive-laden landmines are deployedin the field. One of the major technolo...

  6. Numerical investigation of refrigeration machine compressor operation considering single-phase electric motor dynamic characteristics

    Science.gov (United States)

    Baidak, Y.; Smyk, V.

    2017-08-01

    Using as the base the differential equations system which was presented in relative units for generalized electric motor of hermetic refrigeration compressor, mathematical model of the software for dynamic performance calculation of refrigeration machine compressors drive low-power asynchronous motors was developed. Performed on its ground calculations of the basic model of two-phase electric motor drive of hermetic compressor and the proposed newly developed model of the motor with single-phase stator winding, which is an alternative to the industrial motor winding, have confirmed the benefits of the motor with innovative stator winding over the base engine. Given calculations of the dynamic characteristics of compressor drive motor have permitted to determine the value of electromagnetic torque swinging for coordinating compressor and motor mechanical characteristics, and for taking them into consideration in choosing compressor elements construction materials. Developed and used in the process of investigation of refrigeration compressor drive asynchronous single-phase motor mathematical and software can be considered as an element of computer-aided design system for design of the aggregate of refrigeration compression unit refrigerating machine.

  7. A Comparative Cycle and Refrigerant Simulation Procedure Applied on Air-Water Heat Pumps

    DEFF Research Database (Denmark)

    Mader, Gunda; Palm, Björn; Elmegaard, Brian

    2012-01-01

    A vapor compression heat pump absorbs heat from the environment at a low temperature level and rejects heat at a high temperature level. The bigger the difference between the two temperature levels the more challenging is it to gain high energy efficiency with a basic cycle layout as found in most...... small capacity heat pump applications today. Many of the applicable refrigerants also reach their technical limits regarding low vapor pressure for very low source temperatures and high discharge temperatures for high sink temperatures. These issues are especially manifest for air-water heat pumps. Many...... alternative cycle setups and refrigerants are known to improve the energy efficiency of a vapor compression cycle and reduce discharge temperatures. However not all of them are feasible for small capacity heat pumps from a cost and complexity point of view. This paper presents a novel numerical approach...

  8. Refrigeration and air-conditioning

    CERN Document Server

    Hundy, G H; Welch, T C

    2008-01-01

    Now in its fourth edition, this respected text delivers a comprehensive introduction to the principles and practice of refrigeration. Clear and straightforward, it is designed for students (NVQ/vocational level) and professional HVAC engineers, including those on short or CPD courses. Inexperienced readers are provided with a comprehensive introduction to the fundamentals of the technology. With its concise style yet broad sweep the book covers most of the applications professionals will encounter, enabling them to understand, specify, commission, use and maintain these systems. Many readers w

  9. Hybrid Vapor Compression Adsorption System: Thermal Storage Using Hybrid Vapor Compression Adsorption System

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-04

    HEATS Project: UTRC is developing a new climate-control system for EVs that uses a hybrid vapor compression adsorption system with thermal energy storage. The targeted, closed system will use energy during the battery-charging step to recharge the thermal storage, and it will use minimal power to provide cooling or heating to the cabin during a drive cycle. The team will use a unique approach of absorbing a refrigerant on a metal salt, which will create a lightweight, high-energy-density refrigerant. This unique working pair can operate indefinitely as a traditional vapor compression heat pump using electrical energy, if desired. The project will deliver a hot-and-cold battery that provides comfort to the passengers using minimal power, substantially extending the driving range of EVs.

  10. Energy efficient control of a refrigeration plant

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Larsen, Lars F. S.

    2009-01-01

    This paper proposes a novel method for superheat and capacity control of refrigeration systems. The new idea is to control the superheat by the compressor speed and capacity by the refrigerant flow. A new low order nonlinear model of the evaporator is developed and used in a backstepping design o...... and the methods are evaluated with respect to energy efficiency....

  11. ESO2 Optimization of Supermarket Refrigeration Systems

    DEFF Research Database (Denmark)

    Petersen, Lars Norbert; Madsen, Henrik; Heerup, Christian

    Supermarket refrigeration systems consists of a number of display cases, cooling cabinets and cold rooms connected to a central compressor pack. This configuration saves energy compared to placing a compressor at each cooling site. The classical control setup of a supermarket refrigeration system...

  12. Natural refrigerants. Special issue; Natuurlijke koudemiddelen. Special

    Energy Technology Data Exchange (ETDEWEB)

    Hoogkamer, J.; Forbes Pearson, S.; Van der Sluis, S.M.; Van Gerwen, R.; Gerrard, A.; Roberti, F.; Broeze, J.; Lukasse, L.; Wictor, E.; Oskam, G.; Bouazzaoui, S.; Infante Feirreira, C.A.; Langreck, J.; Gerritsen, J.; Bakker, R.; Uges, P.G.H.; Buitenhuis, H.; Havenaar, D.; Kwakman, N.; Jans, R.

    2008-11-15

    In 21 short and longer articles attention is paid to the use of natural refrigerants as a substitute for current refrigerants. [Dutch] In 21 korte en langere artikelen wordt in dit nummer aandacht besteed aan de toepassing van natuurlijke koudemiddelen als vervanging van de huidige in gebruik zijnde koudemiddelen.

  13. 7 CFR 58.154 - Refrigerated storage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Refrigerated storage. 58.154 Section 58.154 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... § 58.154 Refrigerated storage. Finished product in containers subject to such conditions that will...

  14. ENERGY STAR Certified Commercial Refrigerators and Freezers

    Science.gov (United States)

    Certified models meet all ENERGY STAR requirements as listed in the Version 3.0 ENERGY STAR Program Requirements for Commercial Refrigerators and Freezers that are effective as of October 1, 2014. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=commer_refrig.pr_crit_commercial_refrigerators

  15. An evaluation of EHD enhancement and thermoacoustic refrigeration for Naval applications

    OpenAIRE

    Memory, Stephen B.

    1991-01-01

    An evaluation has been made of two different techniques which could prove valuable for Naval refrigeration needs in the future. The first is electrohydrodynamic (EHD) enhancement of pool boiling and condensation heat transfer; this has been shown to provide significant enhancements for both modes of heat transfer under certain conditions and could provide increases in efficiency of present vapor-compression systems. EHD techniques are quite advanced and prototype condenser and evaporator bund...

  16. Virucidal efficacy of hydrogen peroxide vapour disinfection.

    Science.gov (United States)

    Tuladhar, E; Terpstra, P; Koopmans, M; Duizer, E

    2012-02-01

    Viral contamination of surfaces is thought to be important in transmission. Chemical disinfection can be an effective means of intervention, but little is known about the virucidal efficacy of hydrogen peroxide vapour (HPV) against enteric and respiratory viruses. To measure the virucidal efficacy of HPV against respiratory and enteric viruses on materials representing those found in institutions and homes. Poliovirus, human norovirus genogroup II.4 (GII.4), murine norovirus 1, rotavirus, adenovirus and influenza A (H1N1) virus dried on to stainless steel, framing panel and gauze carriers were exposed to HPV 127 ppm for 1h at room temperature in an isolator. Poliovirus was also exposed to HPV at different locations in a room. The virucidal effect was measured by comparing recoverable viral titres against unexposed controls. Polymerase chain reaction was used to evaluate the effect of HPV on viral genome reduction. HPV disinfection resulted in complete inactivation of all viruses tested, characterized by >4 log(10) reduction in infectious particles for poliovirus, rotavirus, adenovirus and murine norovirus on stainless steel and framing panel carriers, and >2 log(10) reduction for influenza A virus on stainless steel and framing panel carriers, and for all viruses on gauze carriers. Complete inactivation of poliovirus was demonstrated at several locations in the room. Reductions in viral genomes were minimal on framing panel and gauze carriers but significant on stainless steel carriers; human norovirus GII.4 genome was most resistant to HPV treatment. HPV could be an effective virucidal against enteric and respiratory viruses contaminating in-house environments. Copyright © 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  17. Review of investigations in eco-friendly thermoacoustic refrigeration system

    Directory of Open Access Journals (Sweden)

    Raut Ashish S.

    2017-01-01

    Full Text Available To reduce greenhouse gas emissions, internationally research and development is intended to improve the performance of conventional refrigeration system also growth of new-fangled refrigeration technology of potentially much lesser ecological impact. This paper gives brief review of research and development in thermoacoustic refrigeration also the existing situation of thermoacoustic refrigeration system. Thermoacoustic refrigerator is a novel sort of energy conversion equipment which converts acoustic power into heat energy by thermoacoustic effect. Thermoacoustic refrigeration is an emergent refrigeration technology in which there are no moving elements or any environmentally injurious refrigerants during its working. The concept of thermoacoustic refrigeration system is explained, the growth of thermoacoustic refrigeration, various investigations into thermoacoustic refrigeration system, various optimization techniques to improve coefficient of performance, different stacks and resonator tube designs to improve heat transfer rate, various gases, and other parameters like sound generation have been reviewed.

  18. Oil cooled, hermetic refrigerant compressor

    Science.gov (United States)

    English, W.A.; Young, R.R.

    1985-05-14

    A hermetic refrigerant compressor having an electric motor and compressor assembly in a hermetic shell is cooled by oil which is first cooled in an external cooler and is then delivered through the shell to the top of the motor rotor where most of it is flung radially outwardly within the confined space provided by the cap which channels the flow of most of the oil around the top of the stator and then out to a multiplicity of holes to flow down to the sump and provide further cooling of the motor and compressor. Part of the oil descends internally of the motor to the annular chamber to provide oil cooling of the lower part of the motor, with this oil exiting through vent hole also to the sump. Suction gas with entrained oil and liquid refrigerant therein is delivered to an oil separator from which the suction gas passes by a confined path in pipe to the suction plenum and the separated oil drops from the separator to the sump. By providing the oil cooling of the parts, the suction gas is not used for cooling purposes and accordingly increase in superheat is substantially avoided in the passage of the suction gas through the shell to the suction plenum. 3 figs.

  19. Thermofluid Analysis of Magnetocaloric Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Abdelaziz, Omar [ORNL; Gluesenkamp, Kyle R [ORNL; Vineyard, Edward Allan [ORNL; Benedict, Michael [GE Appliances

    2014-01-01

    While there have been extensive studies on thermofluid characteristics of different magnetocaloric refrigeration systems, a conclusive optimization study using non-dimensional parameters which can be applied to a generic system has not been reported yet. In this study, a numerical model has been developed for optimization of active magnetic refrigerator (AMR). This model is computationally efficient and robust, making it appropriate for running the thousands of simulations required for parametric study and optimization. The governing equations have been non-dimensionalized and numerically solved using finite difference method. A parametric study on a wide range of non-dimensional numbers has been performed. While the goal of AMR systems is to improve the performance of competitive parameters including COP, cooling capacity and temperature span, new parameters called AMR performance index-1 have been introduced in order to perform multi objective optimization and simultaneously exploit all these parameters. The multi-objective optimization is carried out for a wide range of the non-dimensional parameters. The results of this study will provide general guidelines for designing high performance AMR systems.

  20. Novel materials for laser refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Hehlen, Markus P [Los Alamos National Laboratory

    2009-01-01

    The status of optical refrigeration of rare-earth-doped solids is reviewed, and the various factors that limit the performance of current laser-cooling materials are discussed. Efficient optical refrigeration is possible in materials for which {Dirac_h}{omega}{sub max} < E{sub p}/8, where {Dirac_h}{omega}{sub max} is the maximum phonon energy of the host material and E{sub p} is the pump energy of the rare-earth dopant. Transition-metal and OH{sup -}impurities at levels >100 ppb are believed to be the main factors for the limited laser-cooling performance in current materials. The many components of doped ZBLAN glass pose particular processing challenges. Binary fluoride glasses such as YF{sub 3}-LiF are considered as alternatives to ZBLAN. The crystalline system KPb{sub 2}CI{sub 5} :Dy{sup 3+} is identified as a prime candidate for high-efficiency laser cooling.

  1. Measurements of Isotopic Composition of Vapour on the Antarctic Plateau

    Science.gov (United States)

    Casado, M.; Landais, A.; Masson-Delmotte, V.; Genthon, C.; Prie, F.; Kerstel, E.; Kassi, S.; Arnaud, L.; Steen-Larsen, H. C.; Vignon, E.

    2015-12-01

    The oldest ice core records are obtained on the East Antarctic plateau. The composition in stable isotopes of water (δ18O, δD, δ17O) permits to reconstruct the past climatic conditions over the ice sheet and also at the evaporation source. Paleothermometer accuracy relies on good knowledge of processes affecting the isotopic composition of surface snow in Polar Regions. Both simple models such as Rayleigh distillation and global atmospheric models with isotopes provide good prediction of precipitation isotopic composition in East Antarctica but post deposition processes can alter isotopic composition on site, in particular exchanges with local vapour. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum water vapour - precipitation - surface snow - buried snow. While precipitation and snow sampling are routinely performed in Antarctica, climatic conditions in Concordia, very cold (-55°C in average) and very dry (less than 1000ppmv), impose difficult conditions to measure the water vapour isotopic composition. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces (down to 20ppmv). Here we present the results of a campaign of measurement of isotopic composition in Concordia in 2014/2015. Two infrared spectrometers have been deployed or the first time on top of the East Antarctic Plateau allowing a continuous vapour measurement for a month. Comparison of the results from infrared spectroscopy with cryogenic trapping validates the relevance of the method to measure isotopic composition in dry conditions. Identification of different behaviour of isotopic composition in the water vapour associated to turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction.

  2. Retrieving mesospheric water vapour from observations of volume scattering radiances

    Directory of Open Access Journals (Sweden)

    P. Vergados

    2009-02-01

    Full Text Available This study examines the possibility for a theoretical approach in the estimation of water vapour mixing ratios in the vicinity of polar mesospheric clouds (PMC using satellite observations of Volume Scattering Radiances (VSR obtained at the wavelength of 553 nm. The PMC scattering properties perturb the underlying molecular Rayleigh scattered solar radiance of the background atmosphere. As a result, the presence of PMC leads to an enhancement in the observed VSR at the altitude of the layer; the PMC VSRs are superimposed on the exponentially decreasing with height Rayleigh VSR, of the PMC-free atmosphere. The ratio between the observed and the Rayleigh VSR of the background atmosphere is used to simulate the environment in which the cloud layer is formed. In addition, a microphysical model of ice particle formation is employed to predict the PMC VSRs. The initial water vapour profile is perturbed until the modelled VSRs match the observed, at which point the corresponding temperature and water vapour profiles can be considered as a first approximation of those describing the atmosphere at the time of the observations. The role of temperature and water vapour in the cloud formation is examined by a number of sensitivity tests suggesting that the water vapour plays a dominant role in the cloud formation in agreement with experimental results. The estimated water vapour profiles are compared with independent observations to examine the model capability in the context of this study. The results obtained are in a good agreement at the peak of the PMC layer although the radiance rapidly decreases with height below the peak. This simplified scenario indicates that the technique employed can give a first approximation estimate of the water vapour mixing ratio, giving rise to the VSR observed in the presence of PMC.

  3. Vapour condensation of R22 retrofit substitutes R417A, R422A and R422D on CuNi turbo C tubes

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-15

    Heat transfer coefficients (HTCs) for outer condensation of R22 and vapours of its retrofit substitutes R417A, R422A and R422D on 90/10 CuNi Turbo C tubes were experimentally measured. The tubes have 19.05 mm nominal outside diameter, 40 fins per inch (1575 fpm) on the outer surface and a smooth inner surface. The effective condensing length per tube was 1895 mm. Experimental data are reported at vapour saturation temperature of 40 C and wall subcoolings from around 1.5 to 8 C. A rapid increase of the HTCs for low wall subcoolings attributable to the presence of the hydrocarbon in the mixtures was found. For wall subcoolings greater than around 3 C, the condensation HTCs slightly increase with raising the wall subcooling and they are for vapours of R417A, R422A and R422D lower by 65-76%, 24-31% and 60-67% than the HTCs for R22, respectively. Comparisons of the condensation performance amongst the different refrigerants and experimental enhancement factors for the condensation of R22 on 90/10 CuNi Turbo C tubes are reported in the paper. (author)

  4. A review of carbon dioxide as a refrigerant in refrigeration technology

    Directory of Open Access Journals (Sweden)

    Paul Maina

    2015-09-01

    Full Text Available Tough environmental laws and stringent government policies have revolutionised the refrigeration sector, especially concerning the cycle fluid known as the refrigerant. It has been observed that only natural refrigerants are environmentally benign. When other refrigerant qualities are considered, especially those relating to toxicity and flammability, carbon dioxide emerges as the best among the natural refrigerants. However, carbon dioxide based refrigerants are not without drawbacks. Even though the use of R744 a carbon dioxide based refrigerant gas has solved the direct effect of emissions on the environment, studies to investigate the indirect effects of these systems are needed. Improvement in existing technical solutions and the formulation of additional solutions to existing R744 refrigeration problems is paramount if this technology is to be accepted by all, especially in areas with warm climates. National policies geared to green technologies are important to clear the way and provide support for these technologies. It is clear that carbon dioxide is one of the best refrigerants and as environmental regulations become more intense, it will be the ultimate refrigerant of the future.

  5. 46 CFR 111.79-15 - Receptacles for refrigerated containers.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Receptacles for refrigerated containers. 111.79-15... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Receptacles § 111.79-15 Receptacles for refrigerated containers. Receptacles for refrigerated containers must meet one of the following: (a) Each receptacle for refrigerated...

  6. 46 CFR 98.25-35 - Refrigerated systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Refrigerated systems. 98.25-35 Section 98.25-35 Shipping... § 98.25-35 Refrigerated systems. (a) Where refrigerated systems are installed to maintain the... acting as a stand-by unit. (c) Refrigerated tanks shall be insulated in conformance with the requirements...

  7. Safety considerations in the design of Spacelab refrigerator/freezer

    Science.gov (United States)

    Hye, A.

    1985-01-01

    A vapor compression refrigerator/freezer has been designed for Spacelab to conduct life sciences experiments. It is equipped with different safety features to eliminate all probable types of failures. The whole Freon loop is enclosed in a second containment so that any leakage of Freon can be contained. The unit is provided with an 'Emergency On' switch to actuate during backup mode which provides the spacecraft power directly to the compressor and the cooling fans while removing the power supply and all normal control elements from the circuit. During this mode, the compressor runs continuously when operating as a freezer (-22 C) and is controlled by a thermostat to cycle when operating as a refrigerator (4 C). It has a push button switch at the front panel to momentarily power the thermometer by a battery to monitor the inside temperature during an emergency. It has a door switch which shuts off the internal cooling fans when the door is opened. All the important critical performance data will be downlinked through a data connector to monitor during mission.

  8. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    DEFF Research Database (Denmark)

    El-Khattam, Amira; Andersen, Mie Them; Hansen, Kurt Kielsgaard

    2014-01-01

    with a ventilated attic where the ceiling may be air tight but has no vapour barrier; post-insulation of the attic may cause the need for a vapour barrier. Placing a vapour barrier above the ceiling can be tiresome and it is difficult to ensure tightness. A simpler way is to paint a vapour barrier directly...... on the ceiling e.g. as an ordinary paint. This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface...

  9. Ferroelectric Stirling-Cycle Refrigerator

    Science.gov (United States)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    1999-01-01

    A Stirling-cycle refrigerator has a three-pump configuration and pumping sequence, in which one pump serves as a compressor. one pump serves as an expander, and one pump serves as a displacer. The pumps are ferroelectrically actuated diaphragm pumps which are coordinated by synchronizing the ferroelectric-actuator voltages in such a way that the net effect of the displacer is to reduce the deleterious effect of dead space; that is, to circulate a greater fraction of the working fluid through the heat exchangers than would be possible by use of the compressor and expander alone. In addition. the displacer can be controlled separately to make the flow of working fluid in the heat exchangers turbulent (to increase the rate of transfer of heat at the cost of greater resistance to flow) or laminar (to decrease the resistance to flow at the cost of a lower heat-transfer rate).

  10. PIPER Continuous Adiabatic Demagnetization Refrigerator

    Science.gov (United States)

    Kimball, Mark O.; Shirron, Peter J.; Canavan, Edgar R.; James, Bryan L.; Sampson, Michael A.; Letmate, Richard V.

    2017-01-01

    We report upon the development and testing of a 4-stage adiabatic demagnetization refrigerator (ADR) capable of continuous cooling at 0.100 Kelvin. This cooler is being built to cool the detector array aboard NASA's Primordial Inflation Polarization Explorer (PIPER) observatory. The goal of this balloon mission is to measure the primordial gravitational waves that should exist if the theory of cosmological inflation is correct. At altitude, the ADR will hold the array of transition-edge sensors at 100 mK continuously while periodically rejecting heat to a 1.2 K pumped helium bath. During testing on ground, the array is held at the same temperature but heat is rejected to a 4.2 K helium bath indicating the flexibility in this coolers design.

  11. Deformation Control of Scroll Compressor for CO2 Refrigerant

    Science.gov (United States)

    Hiwata, Akira; Sawai, Kiyoshi; Morimoto, Takashi; Murakami, Hideki

    The compressors for CO2 refrigerant have a lot of difficulties to achieve high efficiency and reliability because of its very high operating pressure, which causes the deformation for scroll element. The deformations of the fixed scroll during operation fall into the following four categories: (1) pressure deformation due to pressure differences; (2) thermal deformation due to temperature difference; (3) deformation caused by welding for fixing the frame to the shell; and (4) bolt tightening deformation of the compression mechanism. In this study, in order to minimize the deformation during operation, deformations (1) and (2) are grasped by numerical calculations and deformations (3) and (4) are controlled to cancel the deformations (1) and (2) by adjusting the stiffness of fixed scroll. In addition, we measured the deformation under the operation by using the strain gauge in order to confirm that the proper stiffness of fixed scroll can minimize its total amount of deformation.

  12. A cryogenic axial-centrifugal compressor for superfluid helium refrigeration

    CERN Document Server

    Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L

    1997-01-01

    CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.

  13. The maintenance record of the KSTAR helium refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Moon, K. M.; Joo, J. J.; Kim, N. W. [National Fusion Research Institute, Daejeon (Korea, Republic of); and others

    2013-12-15

    Korea Superconducting Tokamak Advanced Research (KSTAR) has a helium refrigeration system (HRS) with the cooling capacity of 9 kW at 4.5 K. Main cold components are composed of 300 tons of superconducting (SC) magnets, main cryostat thermal shields, and SC current feeder system. The HRS comprises six gas storage tanks, a liquid nitrogen tank, the room temperature compression sector, the cold box (C/B), the 1st stage helium distribution box (DB no.1), the PLC base local control system interconnected to central control tower and so on. Between HRS and cold components, there is another distribution box (DB#2) nearby the KSTAR device. The entire KSTAR device was constructed in 2007 and has been operated since 2008. This paper will present the maintenance result of the KSTAR HRS during the campaign and discuss the operation record and maintenance history of the KSTAR HRS.

  14. A versatile magnetic refrigeration test device

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden; Petersen, Thomas Frank; Pryds, Nini

    2008-01-01

    A magnetic refrigeration test device has been built and tested. The device allows variation and control of many important experimental parameters, such as the type of heat transfer fluid, the movement of the heat transfer fluid, the timing of the refrigeration cycle, and the magnitude...... of the applied magnetic field. An advanced two-dimensional numerical model has previously been implemented in order to help in the optimization of the design of a refrigeration test device. Qualitative agreement between the results from model and the experimental results is demonstrated for each of the four...

  15. Mathematical analysis of a Vuilleumier refrigerator.

    Science.gov (United States)

    Sherman, A.

    1971-01-01

    A comprehensive analysis of the Vuilleumier refrigerator was conducted. This analysis includes the effects of nonisothermal gas heat addition and rejection, hot and cold regenerator inefficiencies, conduction losses, and gas leakage losses. A computer program was written which solves the equations resulting from the analysis. The program calculates internal pressures, temperatures, and gas flow rates as functions of refrigerator crank angle, as well as overall refrigerator cooling load and power input. Comparisons between the program results and available data show good agreement, with a marked improvement over the predictions of the ideal model.

  16. A Ross-Stirling spacecraft refrigerator

    Science.gov (United States)

    Walker, G.; Scott, M.; Zylstra, S.

    A spacecraft refrigerator was investigated capable of providing cooling for storage of food and biological samples in the temperature range 0-20 F with cooling capacity in the range of 1 to 2 kW, operating for long periods with great reliability. The system operated on the Stirling refrigeration cycle using the spacecraft life-support gases as the working fluid. A prototype spacecraft Stirling refrigerator was designed, built, and tested with air as the working fluid. The system performance was satisfactory, meeting the requirements specified above. Potential applications for the prototype unit are mentioned.

  17. Refrigerant charge management in a heat pump water heater

    Science.gov (United States)

    Chen, Jie; Hampton, Justin W.

    2014-06-24

    Heat pumps that heat or cool a space and that also heat water, refrigerant management systems for such heat pumps, methods of managing refrigerant charge, and methods for heating and cooling a space and heating water. Various embodiments deliver refrigerant gas to a heat exchanger that is not needed for transferring heat, drive liquid refrigerant out of that heat exchanger, isolate that heat exchanger against additional refrigerant flowing into it, and operate the heat pump while the heat exchanger is isolated. The heat exchanger can be isolated by closing an electronic expansion valve, actuating a refrigerant management valve, or both. Refrigerant charge can be controlled or adjusted by controlling how much liquid refrigerant is driven from the heat exchanger, by letting refrigerant back into the heat exchanger, or both. Heat pumps can be operated in different modes of operation, and segments of refrigerant conduit can be interconnected with various components.

  18. Stabilisation of Collagen Sponges by Glutaraldehyde Vapour Crosslinking

    Directory of Open Access Journals (Sweden)

    Yong Y. Peng

    2017-01-01

    Full Text Available Glutaraldehyde is a well-recognised reagent for crosslinking and stabilising collagens and other protein-based materials, including gelatine. In some cases, however, the use of solutions can disrupt the structure of the material, for example, by causing rapid dispersion or distortions from surface interactions. An alternative approach that has been explored in a number of individual cases is the use of glutaraldehyde vapour. In this study, the effectiveness of a range of different glutaraldehyde concentrations in the reservoir providing vapour, from 5% to 25% (w/v, has been explored at incubation times from 5 h to 48 h at room temperature. These data show the effectiveness of the glutaraldehyde vapour approach for crosslinking collagen and show that materials with defined, intermediate stability could be obtained, for example, to control resorption rates in vivo.

  19. The ignitability of petrol vapours and potential for vapour phase explosion by use of TASER® law enforcement electronic control device.

    Science.gov (United States)

    Clarke, C; Andrews, S P

    2014-12-01

    An experimental study was made of the potential of the TASER-X26™ law enforcement electronic control device to ignite petrol vapours if used by an officer to incapacitate a person soaked in petrol, or within a flammable atmosphere containing petrol vapour. Bench scale tests have shown that a wooden mannequin with pig skin covering the chest was a suitable representation of a human target. Full scale tests using the mannequin have shown that the arc from a TASER-X26™ is capable of igniting petrol/air vapours on a petrol-soaked person. Further tests in a 1/5 scale and a full scale compartment have shown that if a TASER is used within a compartment, a petrol vapour explosion (deflagration) may be achieved. It is evident from this research that if used in a flammable vapour rich environment, the device could prove fatal not only to the target but the TASER® operator as well. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  20. Intercomparison of TCCON and MUSICA Water Vapour Products

    Science.gov (United States)

    Weaver, D.; Strong, K.; Deutscher, N. M.; Schneider, M.; Blumenstock, T.; Robinson, J.; Notholt, J.; Sherlock, V.; Griffith, D. W. T.; Barthlott, S.; García, O. E.; Smale, D.; Palm, M.; Jones, N. B.; Hase, F.; Kivi, R.; Ramos, Y. G.; Yoshimura, K.; Sepúlveda, E.; Gómez-Peláez, Á. J.; Gisi, M.; Kohlhepp, R.; Warneke, T.; Dohe, S.; Wiegele, A.; Christner, E.; Lejeune, B.; Demoulin, P.

    2014-12-01

    We present an intercomparison between the water vapour products from the Total Carbon Column Observing Network (TCCON) and the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA), two datasets from ground-based Fourier Transform InfraRed (FTIR) spectrometers with good global representation. Where possible, comparisons to radiosondes are also included. The near-infrared TCCON measurements are optimized to provide precise monitoring of greenhouse gases for carbon cycle studies; however, TCCON's retrievals also produce water vapour products. The mid-infrared MUSICA products result from retrievals optimized to give precise and accurate information about H2O, HDO, and δD. The MUSICA water vapour products have been validated by extensive intercomparisons with H2O and δD in-situ measurements made from ground, radiosonde, and aircraft (Schneider et al. 2012, 2014), as well as by intercomparisons with satellite-based H2O and δD remote sensing measurements (Wiegele et al., 2014). This dataset provides a valuable reference point for other measurements of water vapour. This study is motivated by the limited intercomparisons performed for TCCON water vapour products and limited characterisation of their uncertainties. We compare MUSICA and TCCON products to assess the potential for TCCON measurements to contribute to studies of the water cycle, water vapour's role in climate and use as a tracer for atmospheric dynamics, and to evaluate the performance of climate models. The TCCON and MUSICA products result from measurements taken using the same FTIR instruments, enabling a comparison with constant instrumentation. The retrieval techniques differ, however, in their method and a priori information. We assess the impact of these differences and characterize the comparability of the TCCON and MUSICA datasets.

  1. Compressive beamforming

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Mosegaard, Klaus

    2014-01-01

    Sound source localization with sensor arrays involves the estimation of the direction-of-arrival (DOA) from a limited number of observations. Compressive sensing (CS) solves such underdetermined problems achieving sparsity, thus improved resolution, and can be solved efficiently with convex...

  2. Spontaneuos and Parametric Processes in Warm Rubidium Vapours

    Directory of Open Access Journals (Sweden)

    Dąbrowski M.

    2014-12-01

    Full Text Available Warm rubidium vapours are known to be a versatile medium for a variety of experiments in atomic physics and quantum optics. Here we present experimental results on producing the frequency converted light for quantum applications based on spontaneous and stimulated processes in rubidium vapours. In particular, we study the efficiency of spontaneously initiated stimulated Raman scattering in the Λ-level configuration and conditions of generating the coherent blue light assisted by multi-photon transitions in the diamond-level configuration. Our results will be helpful in search for new types of interfaces between light and atomic quantum memories.

  3. Experimental performance of carbon dioxide compressor with parallel compression

    Energy Technology Data Exchange (ETDEWEB)

    Bella, Bachir; Kaemmer, Norbert [Emerson Climate Technologies GmbH, Aachen (Germany)

    2011-07-01

    Carbon dioxide (CO2) was proposed in the recent years as a natural fluid to replace the HFCs in refrigeration applications. Its implementation in refrigeration, first in subcritical and recently in transcritical systems is becoming a technology of increasing importance. Trans-critical CO2 system presents lower COP compared to HFCs systems when the ambient temperature is high. Reciprocating compressors with two compression stages having a vapor injection port (VI) have been proposed for parallel compression to improve the efficiency of the system. Many publications have been presented to explain the application advantage but experimental data are lacking to support the theoretical analysis. The work presented here highlight the advantage of the parallel compresion and explains the experimental tests carried-out on a reciprocating prototype with carbon dioxide working with two compression stages (parallel compression) and finally discusses the experimental results. The compressor is a semi-hermetic four cylinders compressor with one compression chamber (cylinder) dedicated to the parallel compression. The tests was performed on hot gas by-pass cycle at -10 C evaporating temperature varying the intermediate and discharge pressures. The experimental result shows the performance at different operating conditions varying the intermediate pressure. It highlights the influence of the intermediate pressure on the efficiency of the compressor and the system. The intermediate pressure influences the volumetric efficiency of the compressor and consequently the COP of the system. Finally, a system efficiency comparison between this configuration and dedicated compressor for parallel compression have been evaluated.

  4. Commercial refrigeration: bet on green fluids; Refrigeration commerciale: pari sur les fluides verts

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2004-08-01

    Thanks to the collaboration between the user (Carrefour supermarkets), the fitter (CEF Nord) and the material manufacturer (Heatcraft Refrigeration), the new Carrefour supermarket of Collegien (Paris region, France) uses CO{sub 2} (R-744) as refrigerating fluid for the negative temperature refrigeration and ice slurries production units for the positive temperature cooling of 6100 m{sup 2} of fresh products. The new installation requires less refrigerating fluid and less maintenance than a classical direct expansion system. The ice slurry system allows to save 15 to 30% of electric power. Short paper. (J.S.)

  5. Page 1 Cryogenic refrigeration methods - 225 from top to bottom ...

    Indian Academy of Sciences (India)

    heat exchangers in the reverse order to the still where the liquid column ends. Here. 'He' is separated from He” by supplying external heat. He vapours are removed by the vacuum pump and the vapours coming out of the still constitute more than 95% of He” since the vapour pressure of He" at 0.6 K is negligible. Referring ...

  6. Designing a magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal...... magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated...... as functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR...

  7. Modelling refrigerant distribution in microchannel evaporators

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  8. Enclosure for thermoelectric refrigerator and method

    Science.gov (United States)

    Park, Brian V. (Inventor); McGrath, Ralph D. (Inventor)

    1997-01-01

    An enclosed structure is provided for use with a refrigerator having a door assembly. The enclosed structure preferably contains superinsulation materials and a plurality of matching drawers. The enclosed structure preferably includes corner joints which minimize thermal energy transfer between adjacent superinsulation panels. The refrigerator may include a cooling system having a thermoelectric device for maintaining the temperature within the refrigerator at selected values. If desired, a fluid cooling system and an active gasket may also be provided between the door assembly and the enclosed structure. The fluid cooling system preferably includes a second thermoelectric device to maintain the temperature of fluid flowing through the active gasket at a selected value. The drawers associated with the refrigerator may be used for gathering, processing, shipping and storing food or other perishable items.

  9. COMPUTER SIMULATION OF A STIRLING REFRIGERATING MACHINE

    Directory of Open Access Journals (Sweden)

    V.V. Trandafilov

    2015-10-01

    Full Text Available In present numerical research, the mathematical model for precise performance simulation and detailed behavior of Stirling refrigerating machine is considered. The mathematical model for alpha Stirling refrigerating machine with helium as the working fluid will be useful in optimization of these machines mechanical design. Complete non-linear mathematical model of the machine, including thermodynamics of helium, and heat transfer from the walls, as well as heat transfer and gas resistance in the regenerator is developed. Non-dimensional groups are derived, and the mathematical model is numerically solved. Important design parameters are varied and their effect on Stirling refrigerating machine performance determined. The simulation results of Stirling refrigerating machine which include heat transfer and coefficient of performance are presented.

  10. Model Based Control of Refrigeration Systems

    DEFF Research Database (Denmark)

    Larsen, Lars Finn Sloth

    for automation of these procedures, that is to incorporate some "intelligence" in the control system, this project was started up. The main emphasis of this work has been on model based methods for system optimizing control in supermarket refrigeration systems. The idea of implementing a system optimizing......-couplings resulting in large disturbances. In supermarkets refrigeration systems the temperature control in the refrigerated display cases are maintained by hysteresis controllers. Based on a model predictive hybrid framework a novel approach for desynchronization is presented. The approach is applied.......e. by degrading the performance. The method has been successfully applied on a test frigeration system for minimization of the power consumption; the hereby gained experimental results will be presented. The present control structure in a supermarket refrigeration system is distributed, which means...

  11. Shuttle Kit Freezer Refrigeration Unit Conceptual Design

    Science.gov (United States)

    Copeland, R. J.

    1975-01-01

    The refrigerated food/medical sample storage compartment as a kit to the space shuttle orbiter is examined. To maintain the -10 F in the freezer kit, an active refrigeration unit is required, and an air cooled Stirling Cycle refrigerator was selected. The freezer kit contains two subsystems, the refrigeration unit, and the storage volume. The freezer must provide two basic capabilities in one unit. One requirement is to store 215 lbs of food which is consumed in a 30-day period by 7 people. The other requirement is to store 128.3 lbs of medical samples consisting of both urine and feces. The unit can be mounted on the lower deck of the shuttle cabin, and will occupy four standard payload module compartments on the forward bulkhead. The freezer contains four storage compartments.

  12. ENERGY STAR Certified Commercial Refrigerators and Freezers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 4.0 ENERGY STAR Program Requirements for Commercial Refrigerators and Freezers that are...

  13. ENERGY STAR Laboratory Grade Refrigerators and Freezers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 1 ENERGY STAR Program Requirements for Laboratory Grade Refrigerators and Freezers that...

  14. Defrost Temperature Termination in Supermarket Refrigeration Systems

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Brian A [ORNL; Sharma, Vishaldeep [ORNL

    2011-11-01

    The objective of this project was to determine the potential energy savings associated with implementing demand defrost strategies to defrost supermarket refrigerated display case evaporators, as compared to the widely accepted current practice of controlling display case defrost cycles with a preset timer. The defrost heater energy use of several representative display case types was evaluated. In addition, demand defrost strategies for refrigerated display cases as well as those used in residential refrigerator/freezers were evaluated. Furthermore, it is anticipated that future work will include identifying a preferred defrost strategy, with input from Retail Energy Alliance members. Based on this strategy, a demand defrost system will be designed which is suitable for supermarket refrigerated display cases. Limited field testing of the preferred defrost strategy will be performed in a supermarket environment.

  15. Natural refrigerants. Future heat pumps for district heating; Naturliga koeldmedier. Framtida vaermepumpar foer fjaerrvaerme

    Energy Technology Data Exchange (ETDEWEB)

    Ingvarsson, Paul; Steen Ronnermark, Ingela [Fortum Teknik och Miljoe AB, Stockholm (Sweden); Eriksson, Marcus [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Chemical Engineering and Environmental Science

    2004-01-01

    International work on refrigerants is aiming at phasing out HFC. The solution might be natural refrigerants. Within 15-20 years, when present heat pumps for district heating in Sweden are likely not in service any longer, it might still be good economy to install new heat pumps since only the machines need to be replaced. This report describes the possibilities to use natural refrigerants. A first screening resulted in further study on some hydrocarbons, ammonia and carbon dioxide. Water was considered to require too large volumes. In present plants it is practically not possible to use any natural refrigerants, partly because the compressors are not adapted. In new plants the situation is different. Today it is technically possible to install new heat pumps in the studied size, 15 MW{sub th}, using ammonia or hydrocarbons as refrigerant. But likely it is very difficult to get permits from authorities since the refrigerants are toxic or highly flammable. There is substantial international research on using carbon dioxide, and this refrigerant is also used in some applications. Carbon dioxide is used at high pressure and in a trans-critical process. Surprisingly, it turned out that one compressor manufacturer considers it possible to supply a heat pump for district heating within 5 years. This development has taken place in Russia, mainly for domestic use. Thus, within 15 to 20 years there will probably exist a technique where carbon dioxide is used. However, more development is needed. Additionally, low district heating return temperatures are also needed to get an acceptable COP. The investment cost for a heat pump installation is considered to be approx. 30 % higher when using ammonia or propane compared to using R134a. When using carbon dioxide there is in the longer run potential to get lower cost than for R134a. The COPs are almost identical if the systems are properly designed. In the carbon dioxide case the COP is somewhat lower, but has a potential for

  16. ADVANCED UNDERGROUND GAS STORAGE CONCEPTS REFRIGERATED-MINED CAVERN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    Limited demand and high cost has prevented the construction of hard rock caverns in this country for a number of years. The storage of natural gas in mined caverns may prove technically feasible if the geology of the targeted market area is suitable; and economically feasible if the cost and convenience of service is competitive with alternative available storage methods for peak supply requirements. It is believed that mined cavern storage can provide the advantages of high delivery rates and multiple fill-withdrawal cycles in areas where salt cavern storage is not possible. In this research project, PB-KBB merged advanced mining technologies and gas refrigeration techniques to develop conceptual designs and cost estimates to demonstrate the commercialization potential of the storage of refrigerated natural gas in hard rock caverns. Five regions of the U.S.A. were studied for underground storage development and PB-KBB reviewed the literature to determine if the geology of these regions was suitable for siting hard rock storage caverns. Area gas market conditions in these regions were also studied to determine the need for such storage. Based on an analysis of many factors, a possible site was determined to be in Howard and Montgomery Counties, Maryland. The area has compatible geology and a gas industry infrastructure for the nearby market populous of Baltimore and Washington D.C.. As Gas temperature is lowered, the compressibility of the gas reaches an optimum value. The compressibility of the gas, and the resultant gas density, is a function of temperature and pressure. This relationship can be used to commercial advantage by reducing the size of a storage cavern for a given working volume of natural gas. This study looks at this relationship and and the potential for commercialization of the process in a storage application. A conceptual process design, and cavern design were developed for various operating conditions. Potential site locations were considered

  17. Positive Displacement Compressor Technology for Refrigeration

    Science.gov (United States)

    Nagatomo, Shigemi

    Trends of compressor technologies for refrigerators, freezers and condensing units are presented in this paper. HFC refrigerants such as R134a and R404C are promising candidates as an altemative for R12. Performance of reciprocating and rotary compressors in the operation with R134A is described. In addition, compressor technologies such as efficiency improvement are described in the cases of reciprocating, rotary and scroll compressors.

  18. Active Sensor Configuration Validation for Refrigeration Systems

    DEFF Research Database (Denmark)

    Hovgaard, Tobias Gybel; Blanke, Mogens; Niemann, Hans Henrik

    2010-01-01

    Major faults in the commissioning phase of refrigeration systems are caused by defects related to sensors. With a number of similar sensors available that do not differ by type but only by spatial location in the plant, interchange of sensors is a common defect. With sensors being used quite...... identify the sensor configuration. The method as such is generic and is shown in the paper to work convincingly on refrigeration systems with significant nonlinear behaviors...

  19. Combined cold compressor/ejector helium refrigerator

    Science.gov (United States)

    Brown, Donald P.

    1985-01-01

    A refrigeration apparatus having an ejector operatively connected with a cold compressor to form a two-stage pumping system. This pumping system is used to lower the pressure, and thereby the temperature of a bath of boiling refrigerant (helium). The apparatus as thus arranged and operated has substantially improved operating efficiency when compared to other processes or arrangements for achieving a similar low pressure.

  20. Simulation of Inviscid Compressible Multi-Phase Flow with Condensation

    Science.gov (United States)

    Kelleners, Philip

    2003-01-01

    Condensation of vapours in rapid expansions of compressible gases is investigated. In the case of high temperature gradients the condensation will start at conditions well away from thermodynamic equilibrium of the fluid. In those cases homogeneous condensation is dominant over heterogeneous condensation. The present work is concerned with development of a simulation tool for computation of high speed compressible flows with homogeneous condensation. The resulting ow solver should preferably be accurate and robust to be used for simulation of industrial flows in general geometries.

  1. Investigation on Dynamic Behavior of Linear Compressor in Stirling-Type Pulse Tube Refrigerator

    Science.gov (United States)

    Ko, Junseok; Jeong, Sangkwon; Kim, Youngkwon

    2008-03-01

    This paper describes the experimental study of the dynamic behavior of a linear compressor in a Stirling-type pulse tube refrigerator (PTR). The dynamic behavior of the piston is closely coupled with the hydraulic force of gas and, therefore, directly influenced by the specific load condition of the pulse tube refrigerator. In the experiment, the frequency response of the pressure at each component, the cooling performance and the piston displacement are measured while an alternate current with fixed magnitude is supplied to the linear motor. The linear compressor in this study was originally designed for a Stirling cryocooler and its maximum input power is approximately 200 W. The pulse tube refrigerator is configured as an in-line type and an inertance tube is incorporated as the phase control device in the pulse tube refrigerator. The pressure difference between both ends of the piston imposes additional stiffness and the PV power in the compression space can be considered a damping effect in the vibration system of the piston. From the experimental results, the effect of the gas force on the dynamic behavior of the piston is discussed. The dynamic relation among the input current, the displacement of the piston, the pulsating pressure and the cooling performance is also studied.

  2. New Solutions for Solar Absorption Refrigeration Systems and Air Conditioning Systems

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2017-04-01

    Full Text Available The mission of the research includes the following objectives: the development of new circuit decisions for the alternate refrigerating systems based on the use of an open absorptive circuit and on the use of solar energy for absorbent solution regeneration; an assessment of the energy and environmental characteristics of the developed systems; obtaining of the experimental data for an assessment of the principal capabilities of the proposed new solar air-conditioning systems. The multistage principle of the creation of drying and cooling contours with the increase of concentration of absorbent on cooler steps is offered. The absorber with internal steam cooling allowing the improvement of the scheme of the alternate refrigerating system is developed. On the basis of the obtained experimental data the analysis of the main opportunities of the developed solar air-conditioning systems was made which showed that the created systems: provide the required comfortable parameters indoors without engaging of traditional refrigerating technics; allow to use only one - or two-stage option of refrigerating system for application in the conditions of Ukraine and of Europe. In comparison with traditional vapor-compression systems, the developed solar systems provide the considerable decrease in energy consumption (to 30%, their use leads to the decrease of exhaustion of natural resources, influences less global climate change.

  3. Design optimization of single mixed refrigerant LNG process using a hybrid modified coordinate descent algorithm

    Science.gov (United States)

    Qyyum, Muhammad Abdul; Long, Nguyen Van Duc; Minh, Le Quang; Lee, Moonyong

    2018-01-01

    Design optimization of the single mixed refrigerant (SMR) natural gas liquefaction (LNG) process involves highly non-linear interactions between decision variables, constraints, and the objective function. These non-linear interactions lead to an irreversibility, which deteriorates the energy efficiency of the LNG process. In this study, a simple and highly efficient hybrid modified coordinate descent (HMCD) algorithm was proposed to cope with the optimization of the natural gas liquefaction process. The single mixed refrigerant process was modeled in Aspen Hysys® and then connected to a Microsoft Visual Studio environment. The proposed optimization algorithm provided an improved result compared to the other existing methodologies to find the optimal condition of the complex mixed refrigerant natural gas liquefaction process. By applying the proposed optimization algorithm, the SMR process can be designed with the 0.2555 kW specific compression power which is equivalent to 44.3% energy saving as compared to the base case. Furthermore, in terms of coefficient of performance (COP), it can be enhanced up to 34.7% as compared to the base case. The proposed optimization algorithm provides a deep understanding of the optimization of the liquefaction process in both technical and numerical perspectives. In addition, the HMCD algorithm can be employed to any mixed refrigerant based liquefaction process in the natural gas industry.

  4. Refrigerant saving automotive air-conditioning system

    Energy Technology Data Exchange (ETDEWEB)

    Muso, M.; Kitahara, Y. (Hitachi, Ltd., Tokyo (Japan))

    1990-06-01

    Based on the phaseout schedule of harmful fleons controlled in the Montreal Protocl, as the first step to alter them into harmless ones, the reduction of fleon consumption was attempted for automotive air-conditioning systems. As saving measures against refrigerant, the following methods were pursued: (1) the volume reduction of air conditioner elements, such as the use of thin pipes, (2) the improvement of liquid and gas secession to reduce a refrigerant weight in a receiver-drier, (3) the reduction of refrigerant leakage from flexible hoses or compressor seals, and (4) more precise determination of a suitable refrigerant weight, such as the adoption of narrower weight tolerance. The low-permeable flexible hose with an inner thin nylon tube was developed, and a suitable refrigerant weight was determined from a register discharge air temperature, and furthermore, the tolerance was narrowed from {plus minus} 0.1kg to {plus minus} 0.05kg. As a result, required refrigerant was successfully reduced by 31-35%. 2 refs., 6 figs., 2 tabs.

  5. The effect the effectiveness of the liquid suction heat exchanger to performance of cold storage with refrigerant R22, R404A and R290/R600a

    Science.gov (United States)

    Prayudi, Nurhasanah, Roswati; Diantari, Retno Aita

    2017-01-01

    Storage space requirements with a large refrigeration capacity they use refrigerants types R22 and R404A. This research to develop alternative technologies to meet the needs of storage space with a large refrigeration capacity. Liquid suction subcooling technology is typically used to obtain improve refrigeration effect at vapor compression refrigeration system. Liquid suction heat exchanger subcooling used a type of tube in tube heat exchanger installed between the condenser and the capillary tube before entering the evaporator. Refrigerant used in this research is R22, R404A, and mixture refrigerant R290/R600a [50:50]. In steady state condition with subcooling temperature evaporator with R290/R600a lower reaches -30°C, lower than R404a and R22 is -24°C and -22°C. Liquid suction heat exchanger subcooling effect on ΔTsub. The cooling effect by the mixture refrigerant of R290/R600a greater than R404a and R22, and liquid suction heat exchanger increase refrigeration capacity index (RCI). The average increase in RCI respectively 3.91%, 7.78%, and 11.87%. Work compressor and compressor work index (CWI) with a mixture refrigerant of R290/R600a greater than R404a and R22, the average work compressor and the working compressor index is greatest mixture refrigerant R290/R600a. CWI respectively is an average of 5.68%, 8.82%, and 11.82%. The average COP, their, liquid suction heat exchanger, respectively are 3.38, 3.18 and 2.63. COPRS with a mixture refrigerant of R290/R600a [50:50] is bigger than the R22 and R404a, and the average COPRS is 5:01%, 5.95%, and 7:41%. A mixture refrigerant R290/R600a [50:50] have the same characteristics as R404a, which can be used as a substitute for refrigerant R22 and R404A.

  6. Speech Compression

    Directory of Open Access Journals (Sweden)

    Jerry D. Gibson

    2016-06-01

    Full Text Available Speech compression is a key technology underlying digital cellular communications, VoIP, voicemail, and voice response systems. We trace the evolution of speech coding based on the linear prediction model, highlight the key milestones in speech coding, and outline the structures of the most important speech coding standards. Current challenges, future research directions, fundamental limits on performance, and the critical open problem of speech coding for emergency first responders are all discussed.

  7. Estimation of vapour pressure and partial pressure of subliming ...

    Indian Academy of Sciences (India)

    Administrator

    temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4- pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined.

  8. Human volunteer study with PGME: Eye irritation during vapour exposure

    NARCIS (Netherlands)

    Emmen, H.H.; Muijser, H.; Arts, J.H.E.; Prinsen, M.K.

    2003-01-01

    The objective of this study was to establish the possible occurrence of eye irritation and subjective symptoms in human volunteers exposed to propylene glycol monomethyl ether (PGME) vapour at concentrations of 0, 100 and 150 ppm. Testing was conducted in 12 healthy male volunteers using a repeated

  9. Microscopic characterisation of suspended graphene grown by chemical vapour deposition

    NARCIS (Netherlands)

    Bignardi, L.; Dorp, W.F. van; Gottardi, S.; Ivashenko, O.; Dudin, P.; Barinov, A.; de Hosson, J.T.M.; Stöhr, M.; Rudolf, P.

    2013-01-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron

  10. Making ET AAS Determination Less Dependent on Vapourization ...

    African Journals Online (AJOL)

    The general solution of the problem comes from the integration of running absorbance normalized with regard to vapour transportation velocity. ... those introduced together with excessive amounts of Mg and Pd. The methodology suggested reduced the error associated with change of atomization kinetics from 20 to 2 %.

  11. Morphology of carbon nanotubes prepared via chemical vapour ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Small angle neutron scattering (SANS) has been utilized to study the morphology of the multi-walled carbon nanotubes prepared by chemical vapour deposition of acetylene. The effects of various synthesis parameters like temperature, catalyst concentration and catalyst support on the size distribution of ...

  12. Morphology of carbon nanotubes prepared via chemical vapour ...

    Indian Academy of Sciences (India)

    Morphology of carbon nanotubes prepared via chemical vapour deposition technique using acetylene: A small angle neutron scattering investigation. D SEN1,∗, K DASGUPTA2, J BAHADUR1, S MAZUMDER1 and. D SATHIYAMOORTHY2. 1Solid State Physics; 2Powder Metallurgy Division, Bhabha Atomic Research ...

  13. Low pressure chemical vapour deposition at quasi-high flow

    NARCIS (Netherlands)

    Holleman, J.; Middelhoek, Jan

    1984-01-01

    A new chemical vapour deposition (CVD) technique is presented. It is especially advantageous for the deposition of compound materials. The technique improves the uniformity and reproducibility of the deposition. The economical use of gaseous reactants is improved by a factor varying between 5 and

  14. Analysis of radiosonde data on tropospheric water vapour in Nigeria ...

    African Journals Online (AJOL)

    The analyses of some atmospheric water vapour parameters derived from radiosonde data at the three existing radiosonde stations in Nigeria are reported. The stations essentially represent the climates of the southern (coastal), middlebelt (savannah), and northern (sub-sahel) regions of the country. Monthly means of the ...

  15. Influence of hydrogen on chemical vapour synthesis of different ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The role of hydrogen in the catalytic chemical vapour deposition of carbon nanotubes using sputtered nickel thin film as a catalyst is explained in this work. The growth of different carbon nanostruc- tures with the variation in the precursor gas content was studied by keeping all other process parameters constant ...

  16. Making ET AAS Determination Less Dependent on Vapourization ...

    African Journals Online (AJOL)

    NICO

    bGerman Aerospace Center, PT-SW, 12489 Berlin, Germany. Received 4 December 2012, revised 5 May 2013, accepted 7 May 2013. ABSTRACT. The quantification of the analytes in ET AAS is normally attained by the measurement and integration of transient absorbance. High degree of atomization and constant vapour ...

  17. Aerosol assisted chemical vapour deposition of germanium thin ...

    Indian Academy of Sciences (India)

    Diethyl germanium bis-picolinate, [Et2Ge(O2CC5H4N)2], and trimethyl germanium quinaldate, [Me3Ge(O2CC9H6N)], have been used as precursors for deposition of thin films of germanium by aerosol assisted chemical vapour deposition (AACVD). The thermogravimetric analysis revealed complete volatilization of ...

  18. Vapour intrusion from the vadose zone—seven algorithms compared

    NARCIS (Netherlands)

    Provoost, J.; Bosman, A.; Reijnders, L.; Bronders, J.; Touchant, K.; Swartjes, F.

    2010-01-01

    Background, aim and scope: Vapours of volatile organic compounds (VOCs) emanating from contaminated soils may move through the unsaturated zone to the subsurface. VOC in the subsurface can be transported to the indoor air by convective air movement through openings in the foundation and basement.

  19. Upper tropospheric water vapour variability over tropical latitudes ...

    Indian Academy of Sciences (India)

    Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements. Ghouse Basha1, M Venkat Ratnam1,∗ and B V Krishna Murthy2. 1National Atmospheric Research Laboratory (NARL), Department of Space, Government of India,. Gadanki, PB No. 123, Tirupati 517 ...

  20. Carbon dioxide and water vapour characteristics on the west coast ...

    Indian Academy of Sciences (India)

    Carbon dioxide and water vapour in the atmo- sphere are considered as the green-house gases and responsible for the global warming, hence much attention has been given to its measurement and analysis (Jones et al. 1978; Jones and Smith 1977;. Leuning et al. 1982; Ohtaki and Matsui 1982;. Ohtaki 1985).

  1. Erratum to: Measurement of copper vapour laser-induced ...

    Indian Academy of Sciences (India)

    Erratum to: Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by. Michelson interferometer. A WAHID. ∗. , S KUNDU, J S B SINGH, A K SINGH, A KHATTAR,. S K MAURYA, J S DHUMAL and K DASGUPTA. Laser & Plasma Technology Division, Beam Technology Development ...

  2. Detection of explosive vapour using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Fang, X.; Ahmad, S. R.

    2009-11-01

    A commercially available nano-structured gold substrate was used for activating surface-enhanced Raman scattering (SERS). Raman spectra of the vapour of explosive material, triacetonetriperoxide (TATP), at trace concentrations produced from adsorbed molecules on such surfaces have been studied. Prominent Raman lines of the explosive molecular species were recorded at a sample temperature of ˜35°C, which is near to human body temperature. For this study, the concentration of the adsorbed TATP molecules on the nano-structured surface was varied by heating the sample to different temperatures and exposing the substrate to the sample vapour for different lengths of time. The intensities of the Raman lines have been found to increase with the increase in temperature and also with the increase in the duration of exposure for a fixed temperature. However, as expected, the Raman intensities have been found to saturate at higher temperatures and longer exposures. These saturation effects of the strengths of the Raman lines in the SERS of TATP vapour have been investigated in this paper. The results indicate that the optimisation for vapour deposition on the surface could be a crucial factor for any quantitative estimate of the concentration of the molecular species adsorbed on the nano-structured substrates.

  3. Variation In Surface Water Vapour Density Over Four Nigerian Stations

    African Journals Online (AJOL)

    The surface water vapour density ρ has been studied using monthly averages of temperature and relative humidity at four selected weather stations in Nigeria for the years 1987 to 1991. It is found that during the dry season months of November to March, ρ is higher at night by an average of about 9.9% than during the day ...

  4. Development of a turbine-compressor for 10 kW class neon turbo-Brayton refrigerator

    Science.gov (United States)

    Hirai, Hirokazu; Hirokawa, Masaki; Yoshida, Shigeru; Sano, Tomonobu; Ozaki, Shinsuke

    2014-01-01

    We are developing 10 kW class turbo-Brayton refrigerator whose working fluid is neon gas. Its high pressure value is 1 MPa and its low pressure value is 0.5 MPa. The refrigerator consists of two turbine-compressors and a heat exchanger. The turbine-compressor has a turbo-expander on one side of its shaft and a turbo-compressor on the other side of the shaft. Two turbo-compressors are connected in series and two turbo-expanders are set in parallel. So, all amount of neon gas is compressed by two stages and each half a mount of neon gas is expanded by one stage. Two turbinecompressors are the same machines and development cost and time are minimized. In this stage, we made one prototype turbine-compressor and installed it in a performance test facility. This paper shows details of the turbine-compressor and refrigerator cooling power simulation results.

  5. New refrigerants: should coldness be more expensive? Book of proceedings; Nouveaux fluides frigorigenes: le froid doit-il couter plus cher? Recueil des interventions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-09-01

    Cold production has become one of the essential needs of our society in several sectors of activity: manufacturing and preservation of some products (food, pharmaceutical, chemical..). For some reasons linked with the environment protection, the refrigerating technique, which seemed to be firmly established, has been deeply reconsidered since about ten years. Changes have become necessary both in the design and the management of equipments. This book of proceedings takes stock of the recent progresses made and on the different existing refrigerating technologies, on their industrial applications and on experience feedbacks. The different contributions deal with the evolution and application of the regulation: characteristics and performances of new refrigerants, advantages and drawbacks of single-phase and two-phase refrigerants, diagnosis of installations, technical and economical interest of cold storage, energy efficiency using self-adaptative condensation, stakes and conditions of use of variable speed compression. (J.S.)

  6. Antifungal Activity of Clove Essential Oil and its Volatile Vapour Against Dermatophytic Fungi

    OpenAIRE

    Chee, Hee Youn; Lee, Min Hee

    2007-01-01

    Antifungal activities of clove essential oil and its volatile vapour against dermatophytic fungi including Candida albicans, Epidermophyton floccosum. Microsporum audouinii, Trichophyton mentagrophytes, and Trichophyton rubrum were investigated. Both clove essential oil and its volatile vapour strongly inhibit spore germination and mycelial growth of the dermatophytic fungi tested. The volatile vapour of clove essential oil showed fungistatic activity whereas direct application of clove essen...

  7. Review of magnetic refrigeration system as alternative to conventional refrigeration system

    Science.gov (United States)

    Mezaal, N. A.; Osintsev, K. V.; Zhirgalova, T. B.

    2017-10-01

    The refrigeration system is one of the most important systems in industry. Developers are constantly seeking for how to avoid the damage to the environment. Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). In the case of ferromagnetic materials, MCE warms as the magnetic moments of the atom are aligned by the application of a magnetic field. There are two types of magnetic phase changes that may occur at the Curie point: first order magnetic transition (FOMT) and second order magnetic transition (SOMT). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative cycle), where the magnetic material matrix works both as a refrigerating medium and as a heat regenerating medium, while the fluid flowing in the porous matrix works as a heat transfer medium. Regeneration can be accomplished by blowing a heat transfer fluid in a reciprocating fashion through the regenerator made of magnetocaloric material that is alternately magnetized and demagnetized. Many magnetic refrigeration prototypes with different designs and software models have been built in different parts of the world. In this paper, the authors try to shed light on the magnetic refrigeration and show its effectiveness compared with conventional refrigeration methods.

  8. Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators

    Science.gov (United States)

    Luo, E.; Gong, M.; Wu, J.; Zhou, Y.

    2004-06-01

    The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the mixtures for achieving liquid nitrogen temperature range will be presented. Secondly, some important conclusions from the optimization of various mixed-refrigerant J-T cycles such as a simple J-T cycle and an auto-cascade mixed-refrigerant J-T cycle will be presented. Moreover, an auto-cascade, mixed-refrigerant J-T refrigerator with a special mixture capable of achieving about 50K will be mentioned. Finally, various prototypes based on the mixed-refrigerant refrigeration technology will be described. These applications include miniature J-T cryocoolers for cooling infrared detectors and high-temperature superconducting devices, cryosurgical knife for medical treatment, low-temperature refrigerators for biological storage and so forth. The on-going research work and unanswered questions for this technology will be also discussed.

  9. SIMULATION RESULTS OF SINGLE REFRIGERANTS FOR USE IN A DUAL-CIRCUIT REFRIGERATOR/FREEZER

    Science.gov (United States)

    The paper reviews the refrigerant/freezer (RF) design and refrigerant selection process that is necessary to design an energy efficient RF that does not use fully halogenated chlorofluorocarbons (CFCs). EPA is interested in phasing out CFCs in RFs to minimize stratospheric ozone ...

  10. 10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.

    Science.gov (United States)

    2010-01-01

    ... vertical. Ice-cream freezer means a commercial freezer that is designed to operate at or below −5 °F (−21... 10 Energy 3 2010-01-01 2010-01-01 false Definitions concerning commercial refrigerators, freezers and refrigerator-freezers. 431.62 Section 431.62 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION...

  11. Correlation between Flow Pattern and Refrigerant Flow Boiling Heat Transfer in Microchannel Heat Sinks

    Science.gov (United States)

    Kuznetsov, V. V.; Kozulin, I. A.; Shamirzaev, A. S.

    2012-11-01

    Flow boiling in microchannel heat sinks is significantly influenced by capillary forces and by boundary constrains affecting the flow pattern and the heat transfer. In the present work, some characteristics of flow boiling heat transfer are explained using measurements of statistical parameters of gas-liquid two-phase flow in a rectangular microchannel. Such statistical characteristics of the flow as length distributions of elongated bubbles and liquid plugs, and also velocity distribution of the elongated bubbles are determined by dual laser scanning of the horizontal adiabatic nitrogen-water flow in a microchannel with the cross-section of 370×217 μm. Pressure gradients in gas-liquid flow are measured, and the results found well matching the predictions that account for capillary pressure on the gas-liquid interface. Heat transfer coefficients are measured for a horizontal copper microchannel heat sink with refrigerant R-21 as the working fluid. The heat sink contains 21 channels with cross section dimensions 930×335-μm. Distribution of local heat transfer coefficients along the length and the width of the microchannel plate is measured in the range of heat fluxes from 14 to 63 kW/m2; vapour quality was varied within 0.05-0.8, and pressure was about 1.6 bar. For flow boiling of R-21 refrigerant, contributions of nucleate boiling and forced convection are comparable. This allows us to examine the heat transfer mechanism for these complex conditions.

  12. Flow boiling of refrigerant-oil mixtures; Transferts de chaleur dans un melange constitue de fluide frigorigene et d'huile

    Energy Technology Data Exchange (ETDEWEB)

    Feidt, M.

    1999-10-13

    The phase out of chlorine containing refrigerants (CFC and HCFC) has led to the introduction of new refrigerants and lubricants to the market. The interest in using HFC fluids as working fluids to replace fluids harmful to the stratospheric ozone layer. The study presents the influence of synthetic oil (POE ISO 68) on flow boiling of refrigerants R134a (pure fluid) and R410A (R32/R125 50%/50%). Local and average heat transfer coefficients and pressure drops have been measured for a smooth horizontal tube. The distribution of the heat transfer coefficient at the inner wall has been obtained from solving the inverse heat conduction problem (IHCP) and resulted in a local combination of nucleate and convective contributions to flow boiling. Local heat transfer coefficients have been averaged and displayed as a function of the vapour quality. For R134a: small amounts of oil (1% to 6%) in the liquid phase increased the heat transfer coefficient at low and intermediate vapour qualities (less than 0.60) compared to pure fluid. However a hugh reduction of the heat transfer has been observed at higher vapour qualities. For R410A : oil dramatically decreases the heat transfer coefficient compared to pure fluid. Pressure drops are also affected by small amounts of lubricant: an important increase has been noted for both fluids. Available design methods for flow boiling heat transfer coefficient (superposition, enhancement, asymptotic) badly predict the experimental results. Nevertheless a new design method accounting for flow patterns has shown good agreements. The influence of the lubricant on the heat transfer is discussed and a new proposition is made to calculate pressure drops. (author)

  13. Low cost microminiature refrigerators for large unit volume applications

    Science.gov (United States)

    Duboc, R. M., Jr.

    1983-01-01

    Photolithographic techniques were employed to fabricate small Joule-Thomson refrigerators in laminated substrates. The gas passages of a J-T refrigerator are formed by etching channels as narrow as 50 microns and as shallow as 5 microns in glass plates which are laminated together. Circular refrigerators on the order of 1.5 centimeters in diameter and .75 millimeters thick were produced which cool down to cryogenic temperatures in a few seconds, using Argon or Nitrogen, with no vacuum or radiation insulation. Smaller refrigerators are developed for both faster cooldown and low refrigeration capacity applications. By using this technology, custom refrigerators can be designed to meet specific application requirements.

  14. Refrigerated Warehouse Demand Response Strategy Guide

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Doug [VaCom Technologies, San Luis Obispo, CA (United States); Castillo, Rafael [VaCom Technologies, San Luis Obispo, CA (United States); Larson, Kyle [VaCom Technologies, San Luis Obispo, CA (United States); Dobbs, Brian [VaCom Technologies, San Luis Obispo, CA (United States); Olsen, Daniel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-11-01

    This guide summarizes demand response measures that can be implemented in refrigerated warehouses. In an appendix, it also addresses related energy efficiency opportunities. Reducing overall grid demand during peak periods and energy consumption has benefits for facility operators, grid operators, utility companies, and society. State wide demand response potential for the refrigerated warehouse sector in California is estimated to be over 22.1 Megawatts. Two categories of demand response strategies are described in this guide: load shifting and load shedding. Load shifting can be accomplished via pre-cooling, capacity limiting, and battery charger load management. Load shedding can be achieved by lighting reduction, demand defrost and defrost termination, infiltration reduction, and shutting down miscellaneous equipment. Estimation of the costs and benefits of demand response participation yields simple payback periods of 2-4 years. To improve demand response performance, it’s suggested to install air curtains and another form of infiltration barrier, such as a rollup door, for the passageways. Further modifications to increase efficiency of the refrigeration unit are also analyzed. A larger condenser can maintain the minimum saturated condensing temperature (SCT) for more hours of the day. Lowering the SCT reduces the compressor lift, which results in an overall increase in refrigeration system capacity and energy efficiency. Another way of saving energy in refrigerated warehouses is eliminating the use of under-floor resistance heaters. A more energy efficient alternative to resistance heaters is to utilize the heat that is being rejected from the condenser through a heat exchanger. These energy efficiency measures improve efficiency either by reducing the required electric energy input for the refrigeration system, by helping to curtail the refrigeration load on the system, or by reducing both the load and required energy input.

  15. A study of alternative refrigerants for the refrigeration and air conditioning sector in Mauritius

    Science.gov (United States)

    Dreepaul, R. K.

    2017-11-01

    The most frequently used refrigerants in the refrigeration and air conditioning (RAC) sector in Mauritius are currently hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC). However, because of their strong influence on global warming and the impact of HCFCs on the ozone layer, refrigerants such as ammonia (NH3), carbon dioxide (CO2) and Hydrocarbons (HC), having minimal impact on the environment, are being considered. So far, HCs have only been safely used in domestic refrigeration. Ammonia has been used mainly for industrial refrigeration whereas CO2 is still under study. In this paper, a comparative study of the various feasible alternatives is presented in a survey that was undertaken with major stake holders in the field. The retrofitting possibility of existing equipment was assessed and safety issues associated with each refrigerant were analysed. The major setback of hydrocarbons as a widely accepted refrigerant is its flammability which was considered as a major safety hazard by the majority of respondents in the survey and the main advantages are the improved equipment coefficient of performance (COP) and better TEWI factor. This resulted in a 12 % drop in energy consumption. Despite the excellent thermodynamic properties of ammonia, its use has mainly been confined to industrial refrigeration due to its toxicity. In Mauritius, the performance of ammonia in air conditioning is being evaluated on a pilot basis. The major setback of carbon dioxide as a refrigerant is the high operating pressure which is considered a safety hazard. The high initial investment cost and the lack of qualified maintenance technician is also an issue. The use of CO2 is mainly being considered in the commercial refrigeration sector.

  16. Performance of V-type Stirling-cycle refrigerator for different working fluids

    Energy Technology Data Exchange (ETDEWEB)

    Tekin, Yusuf; Ataer, Omer Ercan [Erciyes University, Engineering Faculty, Mechanical Engineering Department, Melikgazi, 38 039 Kayseri (Turkey)

    2010-01-15

    The thermodynamic analysis of a V-type Stirling-cycle Refrigerator (VSR) is performed for air, hydrogen and helium as the working fluid and the performance of the VSR is investigated. The V-type Stirling-cycle refrigerator consists of expansion and compression spaces, cooler, heater and regenerator, and it is assumed that the control volumes are subjected to a periodic mass flow. The basic equations of the VSR are derived for per unit crank angle, so time does not appear in the equations. A computer program is prepared in FORTRAN, and the basic equations are solved iteratively. The mass, temperature and density of working fluid in each control volume are calculated for different charge pressures, engine speeds, and for fixed heater and cooler surface temperatures. The work, instantaneous pressure and the COP of the VSR are calculated. The results are obtained for different working fluids, and given by diagrams. (author)

  17. Refrigeration systems with non-azeotropic refrigerant mixtures instead of CNC; Kaelteanlagen mit nichtazeotropen ZKM zur Abloesung der FCKW

    Energy Technology Data Exchange (ETDEWEB)

    Burandt, B.

    1992-10-14

    The use of non-azeotropic refrigerant mixtures in cooling and heat pump systems is energetically favourable. This was proved in process calculations with refrigerants and two-component refrigerant mixtures. The work helps to solve plant problems and shows ways for continuous concentration determination of non-azeotropic refrigerants as well as for the control of refrigeration system in which refrigerant mixtuers are used. (VT) [Deutsch] Die Anwendung nichtazeotroper Kaeltemittel in Kaelte und Waermepumpanlagen weist energetisch guenstigere Eigenschaften aus. Dies wurde durch Prozessberechnungen von Ein- und Zweistoffkaeltemitteln bestaetigt. Die Arbeit traegt zur Loesung anlagetechnischer Probleme und der kontinuierlichen Konzentrationsbestimmung von nichtazeotropen Kaeltemitteln sowie der Regelung von Kaelteanlagen mit Kaeltemitteln bei. (VT

  18. Quantum heat engines and refrigerators: continuous devices.

    Science.gov (United States)

    Kosloff, Ronnie; Levy, Amikam

    2014-01-01

    Quantum thermodynamics supplies a consistent description of quantum heat engines and refrigerators up to a single few-level system coupled to the environment. Once the environment is split into three (a hot, cold, and work reservoir), a heat engine can operate. The device converts the positive gain into power, with the gain obtained from population inversion between the components of the device. Reversing the operation transforms the device into a quantum refrigerator. The quantum tricycle, a device connected by three external leads to three heat reservoirs, is used as a template for engines and refrigerators. The equation of motion for the heat currents and power can be derived from first principles. Only a global description of the coupling of the device to the reservoirs is consistent with the first and second laws of thermodynamics. Optimization of the devices leads to a balanced set of parameters in which the couplings to the three reservoirs are of the same order and the external driving field is in resonance. When analyzing refrigerators, one needs to devote special attention to a dynamical version of the third law of thermodynamics. Bounds on the rate of cooling when Tc→0 are obtained by optimizing the cooling current. All refrigerators as Tc→0 show universal behavior. The dynamical version of the third law imposes restrictions on the scaling as Tc→0 of the relaxation rate γc and heat capacity cV of the cold bath.

  19. Quantum absorption refrigerator with trapped ions

    Science.gov (United States)

    Gan, Jaren; Maslennikov, Gleb; Hablützel Marrero, Roland; Ding, Shiqian; Nimmrichter, Stefan; Roulet, Alexandre; Dai, Jibo; Scarani, Valerio; Matsukevich, Dzmitry

    2017-04-01

    We report on an experimental realization of a quantum absorption refrigerator in a system of the three trapped 171Yb+ ions. The normal modes of motion are coupled by a trilinear Hamiltonian a† bc + h . c . and represent ``hot'', ``work'' and ``cold'' bodies of the refrigerator. We investigate the equilibrium properties of the refrigerator, and demonstrate the absorption refrigeration effect with the modes being prepared in thermal states. We also investigate the coherent dynamics and steady state properties of such a system away from equilibrium operation. We compare the cooling capabilities of thermal versus squeezed thermal states prepared in the work mode as a quantum resource for cooling. Finally, we exploit the coherent dynamics of the system and demonstrate single-shot cooling in the refrigerator. By stopping the evolution in the right moment, we show a significant advantage in cooling as compared to both the steady state and equilibrium performance. This research is supported by the National Research Foundation, Prime Minister's Office, Singapore and the Ministry of Education, Singapore under the Research Centres of Excellence programme.

  20. Data-Driven Control of Refrigeration System

    DEFF Research Database (Denmark)

    Vinther, Kasper

    Refrigeration is used in a wide range of applications, e.g., for storage of food at low temperatures to prolong shelf life and in air conditioning for occupancy comfort. The main focus of this thesis is control of supermarket refrigeration systems. This market is very competitive and it is import......Refrigeration is used in a wide range of applications, e.g., for storage of food at low temperatures to prolong shelf life and in air conditioning for occupancy comfort. The main focus of this thesis is control of supermarket refrigeration systems. This market is very competitive...... conditions make optimal tuning of controllers a difficult and time consuming task. These are also some of the challenges which make advanced model-based control difficult, and a model-based controller will often be tailored to a specific system. The focus in this thesis is therefore instead on development...... of data-driven control strategies with a higher plug and play potential. One of the main control challenges in refrigeration systems is proper control of superheat for efficient and safe operation of the system. This task can be performed by an electronic expansion valve and requires two sensors, which...

  1. Solid-State Quantum Refrigeration

    Science.gov (United States)

    2013-03-01

    are generated.  It has been shown that in strained quantum wells grown on (111B) substrates, the direction of the piezoelectric field is toward...compressively strained quantum well . So that the heavy hole band are pushed upwards in the band diagram and consequently the interband transition with...fifth layer 6 InP 2.5 undoped Quantum well sixth layer  In this structure (VE1889) we put the InAlAs layer inside the InGaAs layer to see if

  2. 75 FR 29823 - Energy Conservation Program for Consumer Products: Test Procedures for Refrigerators...

    Science.gov (United States)

    2010-05-27

    ...'' means an electric refrigerator-freezer. ``Electric refrigerator'' means a cabinet designed for the... Refrigerators, Refrigerator-Freezers, and Freezers; Proposed Rule #0;#0;Federal Register / Vol. 75, No. 102... Conservation Program for Consumer Products: Test Procedures for Refrigerators, Refrigerator-Freezers, and...

  3. Cool sound: the future of refrigeration? Thermodynamic and heat transfer issues in thermoacoustic refrigeration

    Science.gov (United States)

    Herman, C.; Travnicek, Z.

    2006-04-01

    During the past two decades the thermoacoustic refrigeration and prime mover cycles gained importance in a variety of refrigeration applications. Acoustic work, sound, can be used to generate temperature differences that allow the transport of heat from a low temperature reservoir to an ambient at higher temperature, thus forming a thermoacoustic refrigeration system. The thermoacoustic energy pumping cycle can also be reversed: temperature difference imposed along the stack plates can lead to sound generation. In this situation the thermoacoustic system operates as a prime mover. Sound generated by means of this thermoacoustic energy conversion process can be utilized to drive different types of refrigeration devices that require oscillatory flow for their operation, such as thermoacoustic refrigerators, pulse tubes and Stirling engines. In order for a thermoacoustic refrigeration or prime mover system as well as a thermoacoustic prime mover driving a non-thermoacoustic refrigeration system to be competitive on the current market, it has to be optimized in order to improve its overall performance. Optimization can involve improving the performance of the entire system as well as its components. The paper addresses some of the thermodynamic and heat transfer issues relevant in improving the performance of the thermoacoustic system, such as optimization for maximum COP, maximum cooling load and the role of the heat exchangers. Results obtained using the two optimization criteria are contrasted in the paper to illustrate the complexity of the optimization process.

  4. Performance characteristics of a quantum Diesel refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    He Jizhou [Department of Physics, Nanchang University, Nanchang 330031 (China)], E-mail: hjzhou@ncu.edu.cn; Wang Hao; Liu Sanqiu [Department of Physics, Nanchang University, Nanchang 330031 (China)

    2009-04-15

    The Diesel refrigeration cycle using an ideal quantum gas as the working substance is called quantum Diesel refrigeration cycle, which is different from Carnot, Ericsson, Brayton, Otto and Stirling refrigeration cycles. For ideal quantum gases, a corrected equation of state, which considers the quantum behavior of gas particles, is used instead of the classical one. The purpose of this paper is to investigate the effect of quantum gas as the working substance on the performance of a quantum Diesel refrigeration cycle. It is found that coefficients of performance of the cycle are not affected by the quantum degeneracy of the working substance, which is the same as that of the classical Diesel refrigeration cycle. However, the refrigeration load is different from those of the classical Diesel refrigeration cycle. Lastly, the influence of the quantum degeneracy on the performance characteristics of the quantum Diesel refrigeration cycle operated in different temperature regions is discussed.

  5. Performance characteristics of a quantum Diesel refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    He, Jizhou; Wang, Hao; Liu, Sanqiu [Department of Physics, Nanchang University, Nanchang 330031 (China)

    2009-04-15

    The Diesel refrigeration cycle using an ideal quantum gas as the working substance is called quantum Diesel refrigeration cycle, which is different from Carnot, Ericsson, Brayton, Otto and Stirling refrigeration cycles. For ideal quantum gases, a corrected equation of state, which considers the quantum behavior of gas particles, is used instead of the classical one. The purpose of this paper is to investigate the effect of quantum gas as the working substance on the performance of a quantum Diesel refrigeration cycle. It is found that coefficients of performance of the cycle are not affected by the quantum degeneracy of the working substance, which is the same as that of the classical Diesel refrigeration cycle. However, the refrigeration load is different from those of the classical Diesel refrigeration cycle. Lastly, the influence of the quantum degeneracy on the performance characteristics of the quantum Diesel refrigeration cycle operated in different temperature regions is discussed. (author)

  6. A Cold Cycle Dilution Refrigerator for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The cold cycle dilution refrigerator is a continuous refrigerator capable of cooling to temperatures below 100 mK that makes use of a novel thermal magnetic pump....

  7. Retail Food Refrigeration and the Phaseout of HCFC-22

    Science.gov (United States)

    Provides information on the HCFC phaseout that is relevant to food retailers, including alternatives to the use of HCFC-22 in retail food refrigeration, other refrigerant regulations, and resources for more information.

  8. OPTIONS FOR REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    Science.gov (United States)

    The report was prepared to assist personnel responsible for the design, construction, and maintenance of retail food refrigeration equipment in making knowledgeable decisions regarding the implementation of refrigerant-emissions-reducing practices and technologies. It characteriz...

  9. Transitioning to Low-GWP Alternatives in Transport Refrigeration

    Science.gov (United States)

    This fact sheet provides information on low-GWP refrigerant and foam blowing agent alternatives used in transport refrigeration equipment. It discusses HFC alternatives, market trends, challenges to market entry for alternatives, and potential solutions.

  10. Refrigerant pressurization system with a two-phase condensing ejector

    Science.gov (United States)

    Bergander, Mark [Madison, CT

    2009-07-14

    A refrigerant pressurization system including an ejector having a first conduit for flowing a liquid refrigerant therethrough and a nozzle for accelerating a vapor refrigerant therethrough. The first conduit is positioned such that the liquid refrigerant is discharged from the first conduit into the nozzle. The ejector includes a mixing chamber for condensing the vapor refrigerant. The mixing chamber comprises at least a portion of the nozzle and transitions into a second conduit having a substantially constant cross sectional area. The condensation of the vapor refrigerant in the mixing chamber causes the refrigerant mixture in at least a portion of the mixing chamber to be at a pressure greater than that of the refrigerant entering the nozzle and greater than that entering the first conduit.

  11. Systematic modelling and simulation of refrigeration systems

    DEFF Research Database (Denmark)

    Rasmussen, Bjarne D.; Jakobsen, Arne

    1998-01-01

    The task of developing a simulation model of a refrigeration system can be very difficult and time consuming. In order for this process to be effective, a systematic method for developing the system model is required. This method should aim at guiding the developer to clarify the purpose of the s......The task of developing a simulation model of a refrigeration system can be very difficult and time consuming. In order for this process to be effective, a systematic method for developing the system model is required. This method should aim at guiding the developer to clarify the purpose...... of the simulation, to select appropriate component models and to set up the equations in a well-arranged way. In this paper the outline of such a method is proposed and examples showing the use of this method for simulation of refrigeration systems are given....

  12. Basics of Low-temperature Refrigeration

    CERN Document Server

    Alekseev, A.

    2014-07-17

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  13. Toxicity Data to Determine Refrigerant Concentration Limits

    Energy Technology Data Exchange (ETDEWEB)

    Calm, James M.

    2000-09-30

    This report reviews toxicity data, identifies sources for them, and presents resulting exposure limits for refrigerants for consideration by qualified parties in developing safety guides, standards, codes, and regulations. It outlines a method to calculate an acute toxicity exposure limit (ATEL) and from it a recommended refrigerant concentration limit (RCL) for emergency exposures. The report focuses on acute toxicity with particular attention to lethality, cardiac sensitization, anesthetic and central nervous system effects, and other escape-impairing effects. It addresses R-11, R-12, R-22, R-23, R-113, R-114, R-116, R-123, R-124, R-125, R-134, R-134a, R-E134, R-141b, R-142b, R-143a, R-152a, R-218, R-227ea, R-236fa, R-245ca, R-245fa, R-290, R-500, R-502, R-600a, R-717, and R-744. It summarizes additional data for R-14, R-115, R-170 (ethane), R-C318, R-600 (n-butane), and R-1270 (propylene) to enable calculation of limits for blends incorporating them. The report summarizes the data a nd related safety information, including classifications and flammability data. It also presents a series of tables with proposed ATEL and RCL concentrations-in dimensionless form and the latter also in both metric (SI) and inch-pound (IP) units of measure-for both the cited refrigerants and 66 zerotropic and azeotropic blends. They include common refrigerants, such as R-404A, R-407C, R-410A, and R-507A, as well as others in commercial or developmental status. Appendices provide profiles for the cited single-compound refrigerants and for R-500 and R-502 as well as narrative toxicity summaries for common refrigerants. The report includes an extensive set of references.

  14. Refrigerant Distribution Effects on the Performance of Microchannel Evaporators

    OpenAIRE

    Bowers, Chad D.; Mai, Helena; Elbel, Stefan; Hrnjak, Predrag S.

    2012-01-01

    The performance of air to refrigerant heat exchangers can be affected greatly by both refrigerant and air flow distribution. Maldistribution of either fluid stream can lead to reduced heat transfer effectiveness of the heat exchanger and thus lower system efficiency and capacity. Microchannel evaporators are especially susceptible to refrigerant maldistribution as they typically have many parallel channels fed by a common header or manifold. This paper outlines general trends in refrigerant f...

  15. THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2016-06-01

    Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed.

  16. THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2016-02-01

    Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed

  17. Rotatory power of sodium vapour oriented by laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bicchi, P. (Siena Univ. (Italy). Ist. di Fisica); Moi, L.; Zambon, B. (Consiglio Nazionale delle Ricerche, Pisa (Italy). Lab. di Fisica Atomica e Moleculare)

    1979-01-11

    In this paper the rotatory power of sodium vapour is studied when laser light is used as pumping as well as analysis light. The possibility of having an analysis light whose frequency may be varied in a range larger than the interval between the D/sub 1/ and D/sub 2/ atomic lines allows us to get for the first time the complete shape of the rotation curve and to measure a rotation different from zero even for frequencies very far from the resonance ones. The complete orientation in the vapour caused by the laser pumping-light power permits to obtain very high rotation values. In a cell containing Na and 200 Torr of Ne, we measured, at 185/sup 0/C, 10/sup 0//cm of specific rotation. The dependence of the optical activity on the buffer gas pressure and on the frequency of the pumping light is also studied.

  18. Atmospheric radio refractivity and water vapour density at Oshodi ...

    African Journals Online (AJOL)

    ... columnar water vapour density ρ can be used to estimate N over Oshodi, and Kano. For instance, line of regression of N upon ρ for Oshodi at the 0-3km atmospheric column is N = (4.93 ± 0.75) ρ + 254.15 ± 11.26. Keywords: atmospheric humidity, columnar radio refractivity. Nigeria Journal of Pure and Applied Physics Vol ...

  19. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  20. CHEMICAL VAPOUR DEPOSITION OF THE Al-O-N SYSTEM

    OpenAIRE

    Aspar, B.; Armas, B.; Combescure, C.; Thenegal, D.

    1991-01-01

    Using chemical vapour deposition, aluminium - oxygen-nitrogen coatings have been synthesized with aluminium trichloride, hydrogen, ammonia and nitrous oxide. The composition of the equilibrium phases is first determined by a thermodynamic calculation. The only AlON phase we investigate is ([MATH]) spinel aluminium oxynitride and it is considered as a stoichiometric phase with a composition of Al7O9N. The results indicate the existence fields of aluminium nitride and alumina and show the diffi...

  1. Chemical Vapour Deposition of Gas Sensitive Metal Oxides

    OpenAIRE

    Stella Vallejos; Francesco Di Maggio; Tahira Shujah; Chris Blackman

    2016-01-01

    This article presents a review of recent research efforts and developments for the fabrication of metal-oxide gas sensors using chemical vapour deposition (CVD), presenting its potential advantages as a materials synthesis technique for gas sensors along with a discussion of their sensing performance. Thin films typically have poorer gas sensing performance compared to traditional screen printed equivalents, attributed to reduced porosity, but the ability to integrate materials directly with ...

  2. Online load forecasting for supermarket refrigeration

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

    2013-01-01

    This paper presents a study of models for forecasting the load for supermarket refrigeration. The data used for building the forecasting models consists of load measurements, local climate measurements and weather forecasts. The load measurements are from a supermarket located in a village...... in Denmark. Every hour the hourly load for refrigeration for the following 42 hours is forecasted. The forecast models are time adaptive linear time-series models. The dynamic relations between the inputs and the load is modeled by simple transfer functions. The system operates in two regimes: one...

  3. Designing a magnet for magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerk, R.

    2010-03-15

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated as functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR as a function of the magnetic field in order to learn the properties of the optimal magnet assembly. The performance of the AMR as a function of the synchronization and width of the magnetic field with respect to the AMR cycle, the ramp rate and maximum value of the magnetic field are investigated. Other published magnet designs used in magnetic refrigeration devices are also evaluated, using a figure of merit based on the properties of the investigated magnetocaloric materials, to learn the properties of the best magnet designs to date. Following this investigation the Halbach cylinder, which is a hollow permanent magnet cylinder with a rotating remanent flux density, is investigated in detail as it forms the basis of many magnet designs used in magnetic refrigeration. Here the optimal dimensions of a Halbach cylinder, as well as analytical calculations of the magnetic field for a Halbach cylinder of infinite length, are presented. Once it has been determined which properties are desirable for a magnet used in magnetic refrigeration the design of a new magnet is described. This is

  4. Entanglement enhances cooling in microscopic quantum refrigerators.

    Science.gov (United States)

    Brunner, Nicolas; Huber, Marcus; Linden, Noah; Popescu, Sandu; Silva, Ralph; Skrzypczyk, Paul

    2014-03-01

    Small self-contained quantum thermal machines function without external source of work or control but using only incoherent interactions with thermal baths. Here we investigate the role of entanglement in a small self-contained quantum refrigerator. We first show that entanglement is detrimental as far as efficiency is concerned-fridges operating at efficiencies close to the Carnot limit do not feature any entanglement. Moving away from the Carnot regime, we show that entanglement can enhance cooling and energy transport. Hence, a truly quantum refrigerator can outperform a classical one. Furthermore, the amount of entanglement alone quantifies the enhancement in cooling.

  5. Modular Modeling of a Refrigeration Container

    DEFF Research Database (Denmark)

    Kjær Sørensen, Kresten; Juel Skovrup, Morten; M. Jessen, Lars

    2015-01-01

    This paper presents the modeling of a refrigeration container for use as a reference for energy-optimizing controller design. The model is based on first principles in order to conserve mass and energy, but various assumptions are used to simplify the equations, resulting in a unified model...... for the Star Cool refrigeration unit, the container and the cargo. Comparisons between simulations using the model and measurements from a real container show an average error of less than ±1K on the states important for control....

  6. Development of a prototype optical refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, R.I.; Edwards, B.C.; Sigel, G.H.

    1998-01-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have carried out a range of tasks directed toward the construction and testing of a proof-of-principle optical refrigerator prototype. They procured and tested new cooling elements that are at the heart of an optical refrigerator. The cooling element absorbs pump radiation and then fluoresces with nearly unity quantum efficiency. They constructed and tested a cooling chamber with low thermal emissivity walls that reduces the parasitic heating.

  7. Detecting Fan Faults in refrigerated Cabinets

    DEFF Research Database (Denmark)

    Thybo, C.; Rasmussen, B.D.; Izadi-Zamanabadi, Roozbeh

    2002-01-01

    Fault detection in supermarket refrigeration systems is an important topic due to both economic and food safety reasons. If faults can be detected and diagnosed before the system drifts outside the specified operational envelope, service costs can be reduced and in extreme cases the costly...... faults in display cabinets under the wide operational conditions that display cabinets are exposed to. The approach described uses a non- linear parity equation comparing the heat transfer rates of the air and the refrigerant. The paper presents the detection method and discusses the application...

  8. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    Science.gov (United States)

    Yoshida, Suguru; Fujita, Yasunobu

    The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

  9. improvement to the design of a solid absorption solar refrigerator

    African Journals Online (AJOL)

    user

    The paper presents the highlights of the design of an existing solid absorption solar refrigerator, using CaCl2 stabilised ... design of a new model refrigerator, to improve the refrigerator performance are then presented. Introduction ..... O. C. Iloeje, "Parametric Effects on the Performance of a Solar Powered Solid Absorption.

  10. 49 CFR 179.102-17 - Hydrogen chloride, refrigerated liquid.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen chloride, refrigerated liquid. 179.102-17...) § 179.102-17 Hydrogen chloride, refrigerated liquid. Each tank car used to transport hydrogen chloride, refrigerated liquid must comply with the following special requirements: (a) The tank car must comply with...

  11. 49 CFR 179.102-1 - Carbon dioxide, refrigerated liquid.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Carbon dioxide, refrigerated liquid. 179.102-1...) § 179.102-1 Carbon dioxide, refrigerated liquid. (a) Tank cars used to transport carbon dioxide, refrigerated liquid must comply with the following special requirements: (1) All plates for tank, manway nozzle...

  12. 46 CFR 58.20-15 - Installation of refrigerating machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Installation of refrigerating machinery. 58.20-15 Section 58.20-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN... refrigerating machinery. (a) Where refrigerating machines are installed in which anhydrous ammonia is used as a...

  13. Literature survey of heat transfer enhancement techniques in refrigeration applications

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M.K.; Shome, B. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Mechanical Engineering, Aeronautical Engineering and Mechanics

    1994-05-01

    A survey has been performed of the technical and patent literature on enhanced heat transfer of refrigerants in pool boiling, forced convection evaporation, and condensation. Extensive bibliographies of the technical literature and patents are given. Many passive and active techniques were examined for pure refrigerants, refrigerant-oil mixtures, and refrigerant mixtures. The citations were categorized according to enhancement technique, heat transfer mode, and tube or shell side focus. The effects of the enhancement techniques relative to smooth and/or pure refrigerants were illustrated through the discussion of selected papers. Patented enhancement techniques also are discussed. Enhanced heat transfer has demonstrated significant improvements in performance in many refrigerant applications. However, refrigerant mixtures and refrigerant-oil mixtures have not been studied extensively; no research has been performed with enhanced refrigerant mixtures with oil. Most studies have been of the parametric type; there has been inadequate examination of the fundamental processes governing enhanced refrigerant heat transfer, but some modeling is being done and correlations developed. It is clear that an enhancement technique must be optimized for the refrigerant and operating condition. Fundamental processes governing the heat transfer must be examined if models for enhancement techniques are to be developed; these models could provide the method to optimize a surface. Refrigerant mixtures, with and without oil present, must be studied with enhancement devices; there is too little known to be able to estimate the effects of mixtures (particularly NARMs) with enhanced heat transfer. Other conclusions and recommendations are offered.

  14. Development of a Water Based, Critical Flow, Non-Vapor Compression cooling Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hosni, Mohammad H.

    2014-03-30

    Expansion of a high-pressure liquid refrigerant through the use of a thermostatic expansion valve or other device is commonplace in vapor-compression cycles to regulate the quality and flow rate of the refrigerant entering the evaporator. In vapor-compression systems, as the condensed refrigerant undergoes this expansion, its pressure and temperature drop, and part of the liquid evaporates. We (researchers at Kansas State University) are developing a cooling cycle that instead pumps a high-pressure refrigerant through a supersonic converging-diverging nozzle. As the liquid refrigerant passes through the nozzle, its velocity reaches supersonic (or critical-flow) conditions, substantially decreasing the refrigerant’s pressure. This sharp pressure change vaporizes some of the refrigerant and absorbs heat from the surrounding conditions during this phase change. Due to the design of the nozzle, a shockwave trips the supersonic two-phase refrigerant back to the starting conditions, condensing the remaining vapor. The critical-flow refrigeration cycle would provide space cooling, similar to a chiller, by running a secondary fluid such as water or glycol over one or more nozzles. Rather than utilizing a compressor to raise the pressure of the refrigerant, as in a vapor-cycle system, the critical-flow cycle utilizes a high-pressure pump to drive refrigerant liquid through the cooling cycle. Additionally, the design of the nozzle can be tailored for a given refrigerant, such that environmentally benign substances can act as the working fluid. This refrigeration cycle is still in early-stage development with prototype development several years away. The complex multi-phase flow at supersonic conditions presents numerous challenges to fully understanding and modeling the cycle. With the support of DOE and venture-capital investors, initial research was conducted at PAX Streamline, and later, at Caitin. We (researchers at Kansas State University) have continued development

  15. Surface polish of PLA parts in FDM using dichloromethane vapour

    Directory of Open Access Journals (Sweden)

    Jin Yifan

    2017-01-01

    Full Text Available Fused deposition modelling has become one of the most diffused rapid prototyping techniques, which is widely used to fabricate prototypes. However, further application of this technology is severely limited by poor surface roughness. Thus it is necessary to adopt some operations to improve surface quality. Chemical finishing is typically employed to finish parts in fused deposition modelling (FDM. The purpose of this paper is to decrease the surface roughness for polylactic acid (PLA parts in FDM. The chemical reaction mechanism during the treating process is analysed. Then NaOH solution and dichloromethane vapour are used to treat FDM specimens respectively. A 3D laser microscope has been applied to assess the effects in terms of surface topography and roughness. The experimental results show that treatment using dichloromethane vapour performs much better than NaOH solution. Compared with the untreated group, surface roughness obtained through vapour treatment decreases by 88 per cent. This research has been conducted to provide a better method to treat PLA parts using chemical reagents.

  16. Influence of Refrigerant Mass Fraction in the Performance of an Ammonia Absorption Refrigerator

    National Research Council Canada - National Science Library

    TAKESHITA, Keisuke; AMANO, Yoshiharu; HASHIZUME, Takumi; TAKEI, Toshitaka; TOMIZAWA, Masao

    2004-01-01

    .... We propose a method to estimate the refrigerant mass fraction with mass and energy balance equations around the separator at the inlet of the evaporator, and describe the results of experiments which...

  17. Experimental Investigation of COP Using Hydro Carbon Refrigerant in a Domestic Refrigerator

    Science.gov (United States)

    Peyyala, Anusha; Sudheer, N. V. V. S., Dr

    2017-08-01

    Under the Montreal protocol 1987 researchers worked on the possibility of alternative refrigerants like Hydroflourocarbon’s [HFC’s] and Hydrocarbon’s[HC’s] to replace refrigerants Chloroflourocarbon’s [CFC’s] and Hydrochlorofluorocarbons [HCFC’s] in air-conditioning and cooling systems that are destroying the ozone layer. On October 15, 2016 one hundred and ninety plus countries including India came to an agreement called Kigali Amendment to phase out potent green house gases by 2045 there by preventing 0.5 C rise in global temperature by 2050. Under this agreement India agreed to a timeline to reduce the use of HFC’s by 85% of their baseline by 2045. HFC’s are a family of greenhouse gases that are largely used in refrigerators and air conditioners which have reduced the Ozone Depleting Potential [ODP] but increased the Global Warming Potential [GWP]. Refrigeration and its applications are important in almost all branches of industry, so engineers have to become aware of its principles, uses and limitations. Since the decade there are major changes in the choice of refrigerants due to environmental factors. This issue is on-going and new developments should be developed to decrease the environmental problems. So the aim of this paper is to present the experimental analysis of Coefficient of performance [COP] values using R134a [HFC] & R600a [HC] as Refrigerants in Domestic refrigerator using conventional and nonconventional energy sources. Based on the results, usage of R600a in domestic refrigerators will reduce the ODP and also GWP problems which fulfills the nominal requirements of human beings without any effects.

  18. Regenerative sorption compressors for cryogenic refrigeration

    Science.gov (United States)

    Bard, Steven; Jones, Jack A.

    Dramatic efficiency improvements for sorption coolers appear possible with use of compressor heat regeneration techniques. The general theory of sorption compressor heat regeneration is discussed in this paper, and several design concepts are presented. These designs result in long-life, low-vibration cryocoolers that potentially have efficiencies comparable to Stirling refrigerators for 65 to 90 K spacecraft instrument cooling applications.

  19. Eco-Friendly Alternative Refrigeration Systems

    Indian Academy of Sciences (India)

    lies in the development of an air-conditioning system that is light, inexpensive and efficient. The technology ideally lends itself to be used in electric cars, and the cooling process can also be reversed to heat the vehicle. Thermoelectric Refrigeration. Principle of Technology. In 1823, Seebeck discovered that a voltage drop ...

  20. The smallest refrigerators can reach maximal efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Skrzypczyk, Paul; Brunner, Nicolas; Popescu, Sandu [H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Linden, Noah, E-mail: paul.skrzypczyk@bristol.ac.uk, E-mail: n.brunner@bristol.ac.uk [Department of Mathematics, University of Bristol, University Walk, Bristol BS8 1TW (United Kingdom)

    2011-12-09

    We investigate whether size imposes a fundamental constraint on the efficiency of small thermal machines. We analyse in detail a model of a small self-contained refrigerator consisting of three qubits. We show analytically that this system can reach the Carnot efficiency, thus demonstrating that there exists no complementarity between size and efficiency. (fast track communication)

  1. a solid absorbent for solar refrigeration

    African Journals Online (AJOL)

    user

    ABSTRACT. The thermophysical properties of 'Nsukkanut', - a CaCl2/CaSO4 absorbent mixture used in solid absorption solar refrigeration [1], were studied in this report. The transient experimental technique of Beck and Al-Araji. [12] was used in determining the effective thermal conductivity, specific heat and bulk thermal ...

  2. The absoption refrigerator as a thermal transformer

    OpenAIRE

    Herrmann, Friedrich

    2008-01-01

    The absorption refrigerator can be considered a thermal transformer, i.e. a device that is analogous to the electric transformer. The analogy is based on a correspondence between the extensive quantities entropy and electric charge and that of the intensive variables temperature and electric potential.

  3. The Absorption Refrigerator as a Thermal Transformer

    Science.gov (United States)

    Herrmann, F.

    2009-01-01

    The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential. (Contains 1 footnote and 6 figures.)

  4. Air Conditioning and Refrigeration. Book Two.

    Science.gov (United States)

    Wantiez, Gary W.

    This curriculum guide (book II), along with book I, is designed to provide students with the basic skills for an occupation in air conditioning and refrigeration. Six major areas are included, each consisting of one or more units of instruction. These areas and their respective units are titled as follows: Electricity (fundamentals of electricity,…

  5. Anaesthetic potency and physiological effects of refrigerated ...

    African Journals Online (AJOL)

    Several in vitro studies have justified the use of thiopentone solutions beyond the period recommended by the manufacturer. We conducted this in vivo study to investigate the anaesthetic potency and physiological effect of refrigerated thiopentone solution. Rabbits in four groups designated A, B, C and D were ...

  6. Modeling of In-vehicle Magnetic refrigeration

    DEFF Research Database (Denmark)

    Olsen, Ulrik Lund; Bahl, Christian; Engelbrecht, Kurt

    2012-01-01

    A high-performance magnetic refrigeration device is considered as a potential technology for in-vehicle air conditioners in electric vehicles. The high power consumption of a conventional air conditioner in an electric vehicle has considerable impacts on cruising distance. For this purpose...... the demands on cooling power density, temperature difference between hot and cold side, transient properties and COP, will be high....

  7. Microporous Carbon Disks For Sorption Refrigerators

    Science.gov (United States)

    Munukutla, Lakshmi V.; Moore, Mark R.

    1993-01-01

    Slow, carefully controlled pyrolysis found to turn polyvinylidene chloride disks into carbon disks having small pores and large surface areas. Disks exhibit high adsorptivities making them useful in krypton-sorption refrigerators. Carbons made from polyvinylidene chloride have greater adsorptive capacities. Thermal instability controlled and variability of product reduced by careful control of rates of heating, heating times, and rate of final cooling.

  8. Waste Heat Recapture from Supermarket Refrigeration Systems

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Brian A [ORNL

    2011-11-01

    The objective of this project was to determine the potential energy savings associated with improved utilization of waste heat from supermarket refrigeration systems. Existing and advanced strategies for waste heat recovery in supermarkets were analyzed, including options from advanced sources such as combined heat and power (CHP), micro-turbines and fuel cells.

  9. Dynamic Heat Transfer Model of Refrigerated Foodstuff

    DEFF Research Database (Denmark)

    Cai, Junping; Risum, Jørgen; Thybo, Claus

    2006-01-01

    as what is the optimal defrost scheme from food quality point of view are answered. This will serve as a prerequisite of designing of optimal control scheme for the commercial refrigeration system, aiming at optimizing a weighed cost function of both food quality and overall energy consumption of system....

  10. Topology Optimization of Regenerators for Magnetic Refrigeration

    Science.gov (United States)

    Okkels, Fridolin; Panagakos, Grigorios

    2010-11-01

    We show a free form geometrical optimization of a simple regenerator model and how it relates to improvements of magnetic refrigerator systems. Magnetic refrigeration systems utilize the magnetocaloric effect to separate the ambient temperature into hot and cold regions, through a thermodynamic cycle. In the specific model [1], a small-scale regenerator support the temperature difference, and we apply the method of topology optimization to improve the existing design. In order for the high-level implementation of topology optimization to work [2], the model has to be steady state, and therefore the refrigeration cycle has been reformulated, using harmonically varying fields, into an amplitude model. The amplitude model nicely reproduces the results from direct simulation of the thermodynamic cycle, and initial results from the topology optimization are presented. [4pt] [1] T. F. Petersen, "Numerical modelling and analysis of a room temperature magnetic refrigeration system," PhD-thesis, DTU Risø, Denmark (2007)[0pt] [2] L.H. Olesen, F. Okkels, and H. Bruus, Int. J. Num. Meth. Eng. 65, 975 (2006)

  11. Analysis of refrigerant mal-distribution

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    to be two straight tubes. The refrigerant maldistribution is then induced to the evaporator by varying the vapor quality at the inlet to each tube and the air-flow across each tube. Finally it is shown that mal-distribution can be compensated by an intelligent distributor, that ensures equal superheat...

  12. High performance magnetocaloric perovskites for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bahl, Christian R. H.; Velazquez, David; Nielsen, Kaspar K.

    2012-01-01

    We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials...

  13. Hybrid control of the distributed refrigeration system

    DEFF Research Database (Denmark)

    Chen, L.; Wisniewski, R.

    2010-01-01

    consumption. The paper focuses on synchronization dynamics of the refrigeration system modeled as a piecewise-affine switched system. System behaviors are analyzed using chaos theory. The synchronization phenomenon is interpreted as a stable low-period orbit; if the system has a high-order periodic orbit...

  14. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  15. EXERGETIC PERFORMANCE OF A DOMESTIC REFRIGERATOR USING R12 AND ITS ALTERNATIVE REFRIGERANTS

    Directory of Open Access Journals (Sweden)

    BUKOLA O. BOLAJI

    2010-12-01

    Full Text Available Production and use of R12 and other chlorofluorocarbon refrigerants will be prohibited completely all over the world in the year 2010 due to their harmful effects on the earth’s protective ozone layer. Therefore, in this study, the exergetic performance of a domestic refrigerator using two environment-friendly refrigerants (R134a and R152a was investigated and compared with the performance of the system when R12 (an ozone depleting refrigerant was used. The effects of evaporator temperature on the coefficient of performance (COP, exergy flow destruction, exergetic efficiency and efficiency defect in the four major components of the cycle for R12, R134a and R152a were experimentally investigated. The results obtained showed that the average COP of R152a was very close to that of R12 with only 1.4% reduction, while 18.2% reduction was obtained for R134a in comparison with that of R12. The highest average exergetic efficiency of the system (41.5% was obtained using R152a at evaporator temperature of -3.0oC. The overall efficiency defect in the refrigeration cycle working with R152a is consistently better (lower than those of R12 and R134a. Generally, R152a performed better than R134a in terms of COP, exergetic efficiency and efficiency defect as R12 substitute in domestic refrigeration system.

  16. Variable speed hermetic reciprocating compressors for domestic refrigerators

    DEFF Research Database (Denmark)

    Rasmussen, Bjarne D.

    1998-01-01

    This article describes the results of a both theoretical and experimental investigation of the performance of variable speed hermetic reciprocating compressors for domestic refrigerators. The investigation was performed as a part of a larger research project with the objective of reducing...... the energy consumption of domestic refrigerators by increasing the efficiency of the refrigeration system. The improvement of the system efficiency was to be obtained by introducing continuous operation and use variable speed compressors for controlling the capacity of the refrigeration system....... It was the aim of the project to double the efficiency of the refrigeration system and thereby reduce the energy consumption of the refrigerator by 50% compared to a standard refrigerator available on the market to day....

  17. Thermoeconomic model of a commercial transcritical booster refrigeration system

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Elmegaard, Brian

    2011-01-01

    . The booster refrigeration plant consists of one refrigerant cycle supplying refrigerant for evaporators in both cooled and frozen display cases. The detailed numerical model of a refrigeration plant reflects that the trans- and subcritical operation criteria depends on heat rejection performance defined...... by ambient conditions. As two evaporation temperatures are produced from one exergy stream, thermoeconomic theory is used to establish the price of cooling at each individual temperature level based on operating costs. The analysis shows that exergy for cooling frozen displays has approximately double cost......For cooling applications in supermarkets, booster refrigeration systems operating in both transcritical and subcritical conditions are increasingly used. A thermodynamic model of a transcritical booster refrigeration plant is tailored to match the new generation of commercial refrigeration plants...

  18. Recent progress in magnetic refrigeration; Jiki reito no kenkyu doko

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, T. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)

    1997-05-25

    Nearly 20 years have passed since the regular study in magnetic refrigeration commenced. However it has not been put to practical use, because the technology depends largely not only on magnetic materials but also on superconduction magnets, heat switches, and etc. This paper reviews the outline of studies in magnetic refrigeration and their future. The principle of magnetic refrigeration and the merit and demerit are described first under the heading of the special features of magnetic refrigeration. Magnetic materials developed so far are also introduced. Then a Carnot cycle magnetic refrigeration is explained. The study in space satellites by NASA, adiabatic demagnetization refrigerators and etc. are introduced. In the section of magnetic regenerative refrigerators, continuous Carnot active magnetic regenerators (AMR) and Brayton AMR are described. The actual proof study of AMR has been over and the application study has commenced. 36 refs., 14 figs., 2 tabs.

  19. Regenerative characteristics of magnetic or gas Stirling refrigeration cycle

    Science.gov (United States)

    Chen, J.; Yan, Z.

    A general criterion to distinguish whether a Stirling refrigeration cycle possesses the condition of perfect regeneration is given. It is proven using the criterion that a Stirling refrigeration cycle using a simple paramagnetic or ferromagnetic material as the working substance possesses the condition of perfect regeneration, as does a Stirling refrigeration cycle using an ideal or van der Waals gas as the working substance. However, a Stirling refrigeration cycle using a gas which is described by the Redlich-Kwong, Beattie-Bridgeman, Benedict-Webb-Rubin, Dieterici, Berthelot, or Martin-Hou equation as the working substance does not possess the condition of perfect regeneration and its coefficient of performance is always smaller than that of the Carnot refrigeration cycle for the same temperature range. Moreover, the effect of non-perfect regeneration on the level of refrigeration and the coefficient of performance of a Stirling refrigeration cycle is expounded using a strict equation of state.

  20. Factors affecting release of ethanol vapour in active modified atmosphere packaging systems for horticultural products

    Directory of Open Access Journals (Sweden)

    Weerawate Utto

    2014-04-01

    Full Text Available The active modified atmosphere packaging (active MAP system , which provides interactive postharvest control , using ethanol vapour controlled release, is one of the current interests in the development of active packaging for horticultural products. A number of published research work have discussed the relationship between the effectiveness of ethanol vapour and its concentration in the package headspace, including its effect on postharvest decay and physiological controls. This is of importance because a controlled release system should release and maintain ethanol vapour at effective concentrations during the desired storage period. A balance among the mass transfer processes of ethanol vapour in the package results in ethanol vapour accumulation in the package headspace. Key factors affecting these processes include ethanol loading, packaging material, packaged product and storage environment (temperature and relative h umidity. This article reviews their influences and discusses future work required to better understand their influences on ethanol vapour release and accumulations in active MAP.

  1. Numerical analysis of the transient flow in a scroll refrigeration compressor

    Science.gov (United States)

    Sun, Shuaihui; Wu, Kai; Guo, Pengcheng; Luo, Xingqi

    2017-08-01

    In the present paper, the CFD technology is adopted to simulate the working process of a scroll refrigeration compressor with R22 as working fluid. The structural grids in the scroll compressor were updated continually during the solving process to cope with the movement boundaries of the fluid domain. The radial meshing clearance was 0.008 mm which was the same with that in the real prototype. The pressure, velocity and temperature distribution in chambers of compressor were computed. Also, the transient mass flux diagrams were calculated out. The results indicated that the pressure was asymmetrical in the two symmetrical suction chambers, because the suction port and passage were not absolutely symmetrical. The gradient of temperature was great in each working chamber due to leakage flow. Velocity vector distribution was asymmetrical in each pair of working chamber owing to the movement of orbiting scroll; the flow was complicated in the central working chamber. The movement of the orbiting scroll had different influence on the vortexes formation in each pair of compression chamber. The inlet and outlet mass flux fluctuated with the crank angle obviously. Because of the ‘cut-off’ of the refrigeration fluid in the suction chamber when the crank angle was larger than 220°, the inlet mass flux decreased remarkably. Finally, some useful advices were given to improve the performance of the scroll refrigeration compressor.

  2. Numerical Investigation of Flow Losses through Discharge Line of Household Type Refrigerator Compressors

    Science.gov (United States)

    Yesilaydin, I.; Erbay, L. B.

    2015-08-01

    The technological developments, competition and energy policies are forcing the refrigeration market to increase the efficiency of their products as never before. The component that determines the performance and efficiency of the refrigeration system is the compressor, which is the major energy consumer in a compression refrigeration system. One of the essential elements of the total compressor efficiency is the discharge line flow efficiency that is subjected to this study. In this paper, the effects of design parameters on flow loses at discharge line of a hermetic reciprocating compressor were investigated with numerical flow analysis. At this study, three conceptual designs were modelled based on the discharge line design parameters such as line diameter, resonator volumes and line length. The pressure drop regions are determined by CFD analyses and they compared against the base model. Analyses are carried out by using commercial CFD software. Furthermore, the obtained numerical results were compared to experimental data and presented a good agreement in terms of pressure drop and discharge line flow efficiency.

  3. Taguchi Method for Development of Mass Flow Rate Correlation using Hydrocarbon Refrigerant Mixture in Capillary Tube

    Directory of Open Access Journals (Sweden)

    Shodiya Sulaimon

    2014-07-01

    Full Text Available The capillary tube is an important control device used in small vapor compression refrigeration systems such as window air-conditioners, household refrigerators and freezers. This paper develops a non-dimensional correlation based on the test results of the adiabatic capillary tube for the mass flow rate through the tube using a hydrocarbon refrigerant mixture of 89.3% propane and 10.7% butane (HCM. The Taguchi method, a statistical experimental design approach, was employed. This approach explores the economic benefit that lies in studies of this nature, where only a small number of experiments are required and yet valid results are obtained. Considering the effects of the capillary tube geometry and the inlet condition of the tube, dimensionless parameters were chosen. The new correlation was also based on the Buckingham Pi theorem. This correlation predicts 86.67% of the present experimental data within a relative deviation of -10% to +10%. The predictions by this correlation were also compared with results in published literature.

  4. OPTIMAL DESIGN AND OPERATION OF HELIUM REFRIGERATION SYSTEMS USING THE GANNI CYCLE

    Energy Technology Data Exchange (ETDEWEB)

    Venkatarao Ganni, Peter Knudsen

    2010-04-01

    The constant pressure ratio process, as implemented in the floating pressure - Ganni cycle, is a new variation to prior cryogenic refrigeration and liquefaction cycle designs that allows for optimal operation and design of helium refrigeration systems. This cycle is based upon the traditional equipment used for helium refrigeration system designs, i.e., constant volume displacement compression and critical flow expansion devices. It takes advantage of the fact that for a given load, the expander sets the compressor discharge pressure and the compressor sets its own suction pressure. This cycle not only provides an essentially constant system Carnot efficiency over a wide load range, but invalidates the traditional philosophy that the (‘TS’) design condition is the optimal operating condition for a given load using the as-built hardware. As such, the Floating Pressure- Ganni Cycle is a solution to reduce the energy consumption while increasing the reliability, flexibility and stability of these systems over a wide operating range and different operating modes and is applicable to most of the existing plants. This paper explains the basic theory behind this cycle operation and contrasts it to the traditional operational philosophies presently used.

  5. MATHEMATICAL MODEL FOR THE STUDY AND DESIGN OF A ROTARY-VANE GAS REFRIGERATION MACHINE

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2016-08-01

    Full Text Available This paper presents a mathematical model of calculating the main parameters the operating cycle, rotary-vane gas refrigerating machine that affect installation, machine control and working processes occurring in it at the specified criteria. A procedure and a graphical method for the rotary-vane gas refrigerating machine (RVGRM are proposed. A parametric study of the main geometric variables and temperature variables on the thermal behavior of the system is analyzed. The model considers polytrope index for the compression and expansion in the chamber. Graphs of the pressure and temperature in the chamber of the angle of rotation of the output shaft are received. The possibility of inclusion in the cycle regenerative heat exchanger is appreciated. The change of the coefficient of performance machine after turning the cycle regenerative heat exchanger is analyzed. It is shown that the installation of a regenerator RVGRM cycle results in increased COP more than 30%. The simulation results show that the proposed model can be used to design and optimize gas refrigerator Stirling.

  6. IEA Annex 26: Advanced Supermarket Refrigeration/Heat Recovery Systems

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, VAN

    2003-05-19

    With increased concern about the impact of refrigerant leakage on global warming, a number of new supermarket refrigeration system configurations requiring significantly less refrigerant charge are being considered. In order to help promote the development of advanced systems and expand the knowledge base for energy-efficient supermarket technology, the International Energy Agency (IEA) established IEA Annex 26 (Advanced Supermarket Refrigeration/Heat Recovery Systems) under the ''IEA Implementing Agreement on Heat Pumping Technologies''. Annex 26 focuses on demonstrating and documenting the energy saving and environmental benefits of advanced systems design for food refrigeration and space heating and cooling for supermarkets. Advanced in this context means systems that use less energy, require less refrigerant and produce lower refrigerant emissions. Stated another way, the goal is to identify supermarket refrigeration and HVAC technology options that reduce the total equivalent warming impact (TEWI) of supermarkets by reducing both system energy use (increasing efficiency) and reducing total refrigerant charge. The Annex has five participating countries: Canada, Denmark, Sweden, the United Kingdom, and the United States. The working program of the Annex has involved analytical and experimental investigation of several candidate system design approaches to determine their potential to reduce refrigerant usage and energy consumption. Advanced refrigeration system types investigated include the following: distributed compressor systems--small parallel compressor racks are located in close proximity to the food display cases they serve thus significantly shortening the connecting refrigerant line lengths; secondary loop systems--one or more central chillers are used to refrigerate a secondary coolant (e.g. brine, ice slurry, or CO2) that is pumped to the food display cases on the sales floor; self-contained display cases--each food display case

  7. The Seasonal Cycle of Water Vapour on Mars from Assimilation of Thermal Emission Spectrometer Data

    Science.gov (United States)

    Steele, Liam J.; Lewis, Stephen R.; Patel, Manish R.; Montmessin, Franck; Forget, Francois; Smith, Michael D.

    2014-01-01

    We present for the first time an assimilation of Thermal Emission Spectrometer (TES) water vapour column data into a Mars global climate model (MGCM). We discuss the seasonal cycle of water vapour, the processes responsible for the observed water vapour distribution, and the cross-hemispheric water transport. The assimilation scheme is shown to be robust in producing consistent reanalyses, and the global water vapour column error is reduced to around 2-4 pr micron depending on season. Wave activity is shown to play an important role in the water vapour distribution, with topographically steered flows around the Hellas and Argyre basins acting to increase transport in these regions in all seasons. At high northern latitudes, zonal wavenumber 1 and 2 stationary waves during northern summer are responsible for spreading the sublimed water vapour away from the pole. Transport by the zonal wavenumber 2 waves occurs primarily to the west of Tharsis and Arabia Terra and, combined with the effects of western boundary currents, this leads to peak water vapour column abundances here as observed by numerous spacecraft. A net transport of water to the northern hemisphere over the course of one Mars year is calculated, primarily because of the large northwards flux of water vapour which occurs during the local dust storm around L(sub S) = 240-260deg. Finally, outlying frost deposits that surround the north polar cap are shown to be important in creating the peak water vapour column abundances observed during northern summer.

  8. Water vapour loss threshold and induction of cholinergic urticaria.

    Science.gov (United States)

    Tupker, R A; Doeglas, H M

    1990-01-01

    A patient is described with cholinergic urticaria (CU) in whom the symptoms could be provoked by gustatory stimuli. The aim of this study was to investigate whether there is a threshold of sweating (monitored by skin water vapour loss (SVL) measurements) at which CU can be provoked. Provocations with lemon and sal-ammoniac liquorice induced transient sweating differing both in degree and duration. Only 'doubly salted' liquorice, which caused the most intense sweat response, resulted in urticarial lesions. This findings suggest a threshold dependency for the induction of CU. SVL measurement may be a useful method for the evaluation of sweating tests in CU patients.

  9. Combustion dynamics of low vapour pressure nanofuel droplets

    Science.gov (United States)

    Pandey, Khushboo; Chattopadhyay, Kamanio; Basu, Saptarshi

    2017-07-01

    Multiscale combustion dynamics, shape oscillations, secondary atomization, and precipitate formation have been elucidated for low vapour pressure nanofuel [n-dodecane seeded with alumina nanoparticles (NPs)] droplets. Dilute nanoparticle loading rates (0.1%-1%) have been considered. Contrary to our previous studies of ethanol-water blend (high vapour pressure fuel), pure dodecane droplets do not exhibit internal boiling after ignition. However, variation in surface tension due to temperature causes shape deformations for pure dodecane droplets. In the case of nanofuels, intense heat release from the enveloping flame leads to the formation of micron-size aggregates (of alumina NPS) which serve as nucleation sites promoting heterogeneous boiling. Three boiling regimes (A, B, and C) have been identified with varying bubble dynamics. We have deciphered key mechanisms responsible for the growth, transport, and rupture of the bubbles. Bubble rupture causes ejections of liquid droplets termed as secondary atomization. Ejection of small bubbles (mode 1) resembles the classical vapour bubble collapse mechanism near a flat free surface. However, large bubbles induce severe shape deformations as well as bulk oscillations. Rupture of large bubbles results in high speed liquid jet formation which undergoes Rayleigh-Plateau tip break-up. Both modes contribute towards direct fuel transfer from the droplet surface to flame envelope bypassing diffusion limitations. Combustion lifetime of nanofuel droplets consequently has two stages: stage I (where bubble dynamics are dominant) and stage II (formation of gelatinous mass due to continuous fuel depletion; NP agglomeration). In the present work, variation of flame dynamics and spatio-temporal heat release (HR) have been analysed using high speed OH* chemiluminescence imaging. Fluctuations in droplet shape and flame heat release are found to be well correlated. Droplet flame is bifurcated in two zones (I and II). Flame response is

  10. Chemical vapour deposited diamonds for dosimetry of radiotherapeutical beams

    Energy Technology Data Exchange (ETDEWEB)

    Bucciolini, M.; Mazzocchi, S. [Firenze Univ., Firenze (Italy). Dipartimento di Fisiopatologia Clinica; INFN, Firenze (Italy); Borchi, E.; Bruzzi, M.; Pini, S.; Sciortino, S. [Firenze Univ., Firenze (Italy). Dipartimento di Energetica; INFN, Firenze (Italy); Cirrone, G.A.P.; Guttone, G.; Raffaele, L.; Sabini, M.G. [INFN, Catania (Italy). Laboratori Nazionali del Sud

    2002-07-01

    This paper deals with the application of synthetic diamond detectors to the clinical dosimetry of photon and electron beams. It has been developed in the frame of INFN CANDIDO project and MURST Cofin. Diamonds grown with CVD (Chemical Vapour Deposition) technique have been studied; some of them are commercial samples while others have been locally synthesised. Experiments have been formed using both on-line and off-line approaches. For the off-line measurements, TL (thermoluminescent) and TSC (thermally stimulated current) techniques have been used.

  11. Silicon nanowire arrays as learning chemical vapour classifiers

    Energy Technology Data Exchange (ETDEWEB)

    Niskanen, A O; Colli, A; White, R; Li, H W; Spigone, E; Kivioja, J M, E-mail: antti.niskanen@nokia.com [Nokia Research Center, Broers Building, 21 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2011-07-22

    Nanowire field-effect transistors are a promising class of devices for various sensing applications. Apart from detecting individual chemical or biological analytes, it is especially interesting to use multiple selective sensors to look at their collective response in order to perform classification into predetermined categories. We show that non-functionalised silicon nanowire arrays can be used to robustly classify different chemical vapours using simple statistical machine learning methods. We were able to distinguish between acetone, ethanol and water with 100% accuracy while methanol, ethanol and 2-propanol were classified with 96% accuracy in ambient conditions.

  12. Analysis of Refrigeration Cycle Performance with an Ejector

    Directory of Open Access Journals (Sweden)

    Wani J. R.

    2016-01-01

    Full Text Available A conventional refrigeration cycle uses expansion device between the condenser and the evaporator which has losses during the expansion process. A refrigeration cycle with ejector is a promising modification to improve the performance of conventional refrigeration cycle. The ejector is used to recover some of the available work so that the compressor suction pressure increases. To investigate the enhancement a model with R134a refrigerant was developed. To solve the set of equations and simulate the cycle performance a subroutine was written on engineering equation solver (EES environment. At specific conditions, the refrigerant properties are obtained from EES. At the design conditions the ejector refrigeration cycle achieved 5.141 COP compared to 4.609 COP of the conventional refrigeration cycle. This means that ejector refrigeration cycle offers better COP with 10.35% improvement compared to conventional refrigeration cycle. Parametric analysis of ejector refrigeration cycle indicated that COP was influenced significantly by evaporator and condenser temperatures, entrainment ratio and diffuser efficiency.

  13. Performance simulation of refrigerated display cabinets operating with refrigerants R22 and R404A

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Y.T. [Mechanical Engineering, School of Engineering and Design, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom); Cropper, R. [Formerly School of Engineering, North East Wales Institute, Plas Coch Campus, Mold Road, Wrexham L11 2AW (United Kingdom)

    2008-08-15

    This paper describes the analysis and performance comparison of a display cabinet system using refrigerant R404A and its substitute refrigerant R22. The model of the display cabinet is developed at steady state and integrated from three main component sub-models, air-cooling finned-tube evaporator, air curtain and display cabinet body. The evaporator model is built up based on the distributed method, which can simulate the heat exchangers with different circuit structures. The frost effect on the performance of the evaporator is included in the model. The correlations for the heat transfer and pressure drop calculations of both air and refrigerant sides are purposely selected in the evaporator model. In addition, the evaporator model has been validated with experimental results at steady states from published literature. Several correlated functions from the detailed numerical solution are used for the model of the air curtain. Some simplifications are also utilized for the model of display cabinet body. The performance simulation and comparison of the display cabinet using refrigerants R404A and R22 are carried out at different indoor ambient conditions especially at varied ambient air humidity to mimic the actual indoor space conditions in super stores. Some significant results such as the comparison of cooling load requirement for different refrigerant display cases have been obtained from the simulation, which can significantly contribute to the optimal cabinet design and operating analysis. (author)

  14. Design of refrigeration system using refrigerant R134a for macro compartment

    Science.gov (United States)

    Rani, M. F. H.; Razlan, Z. M.; Shahriman, A. B.; Yong, C. K.; Harun, A.; Hashim, M. S. M.; Faizi, M. K.; Ibrahim, I.; Kamarrudin, N. S.; Saad, M. A. M.; Zunaidi, I.; Wan, W. K.; Desa, H.

    2017-10-01

    The main objective of this study is to analyse and design an optimum cooling system for macro compartment. Current product of the refrigerator is not specified for single function and not compact in size. Hence, a refrigeration system using refrigerant R134a is aimed to provide instant cooling in a macro compartment with sizing about 150 × 150 × 250 mm. The macro compartment is purposely designed to fit a bottle or drink can, which is then cooled to a desired drinking temperature of about 8°C within a period of 1 minute. The study is not only concerned with analysing of heat load of the macro compartment containing drink can, but also focused on determining suitable heat exchanger volume for both evaporator and condenser, calculating compressor displacement value and computing suitable resistance value of the expansion valve. Method of optimization is used to obtain the best solution of the problem. Mollier diagram is necessary in the process of developing the refrigeration system. Selection of blower is made properly to allow air circulation and to increase the flow rate for higher heat transfer rate. Property data are taken precisely from thermodynamic property tables. As the main four components, namely condenser, compressor, evaporator and expansion valve are fully developed, the refrigeration system is complete.

  15. An optimized magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2010-01-01

    A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction...... of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T also in a 2 L volume. The working point of all the permanent magnet blocks in the design is very close...... to the maximum energy density. The final design is characterized in terms of a performance parameter, and it is shown that it is one of the best performing magnet designs published for magnetic refrigeration....

  16. Synchronization Analysis of the Supermarket Refrigeration System

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Chen, Liang; Larsen, Lars Finn Sloth

    2009-01-01

    The supermarket refrigeration system typically has a distributed control structure, which neglects interactions between its subsystems. These interactions from time to time lead to a synchronization operation of the display-cases which causes an inferior control performance and increased energy...... consumption. The paper focuses on synchronization dynamics of the refrigeration system modeled as a piecewiseaffine switched system. Stability analysis is performed bygluing the subsystems and polyhedra together to form a single dynamical system defined on a coherent state space. Then, system behavior...... is analyzed using the bifurcation and chaos theory. It is demonstrated that the system can have a complex chaotic behavior, which is far from the synchronization. This shows that making the system chaotic is a good choice for a de-synchronization strategy. The positive maximum Lyapunov exponent is usually...

  17. Energy analysis of a supermarket refrigeration system

    DEFF Research Database (Denmark)

    Jensen, Jakob Munch; Jakobsen, Arne; Rasmussen, Bjarne D.

    1999-01-01

    From 1995 to 1998, an energy test method for supermarket refrigeration systems was developed in a project financed by the Danish Energy Agency. The purpose of the energy test method is to provide the means for evaluating the energy efficiency of these systems. The test method requires measurements...... of air temperatures and energy consumption to be carried out on the selected supermarket refrigeration system. In addition to the measurements required by the method, more measurements of individual energy consumptions have been carried in the case described in this paper. The purpose of the additional...... systems and therefore the experience with its application is limited. In the future, the energy test method may be used for evaluation of the efficiency of a new system or the improvement in efficiency when optimising an existing system....

  18. 78 FR 55889 - Energy Conservation Program: Energy Conservation Standards for Commercial Refrigeration Equipment

    Science.gov (United States)

    2013-09-11

    ... refrigerator-freezers with solid doors, and self-contained commercial refrigerators designed for pull-down... designed for holding temperatures \\14\\ (i.e., commercial refrigerators, freezers, and refrigerator-freezers.... Representative Unit Selection b. Baseline Models 2. Design Options 3. Refrigerants 4. Cost Assessment Methodology...

  19. Hey you! Shut the refrigerator door!

    Science.gov (United States)

    Fay, Sarah; Portenga, Angela

    1998-09-01

    The note discusses electrical power and energy and includes possible labs to be used in a physics classroom. It is based on our experimentation with a new device called the Watt-Watt/Hour Meter, which displays instantaneous power and cumulative energy readings of household electrical devices. Our experiments utilized this meter in conjunction with various appliances and focused primarily on its use with a refrigerator.

  20. Synchronized acoustic refrigerator and heat engine (SARAH)

    OpenAIRE

    Banerjee, Aayan; Nayak, Gaurav

    2011-01-01

    In light of the present global energy scenario, it is imperative to seek novel and efficient energy solutions to redress the situation. Solar energy, wind energy, geothermal energy, ocean thermoclines and waste heat recovery are the major players in the sustainable energy field. In this paper we propose a Synchronized Acoustic Refrigerator And Heat Engine (SARAH), a Thermoacoustic (TA) device capable of harnessing these untapped sources in a cost-effective and efficient way on both small and ...

  1. 3D magnetometer for a dilution refrigerator

    Science.gov (United States)

    Uchaikin, S.; Likhachev, A.; Cioata, F.; Perminov, I.; Sanghera, H.; Singh, I.; Spear, P.; Chavez, P.; Han, X.; Petroff, C.; Rich, C.

    2012-12-01

    In this report, we describe a development of a three dimensional system for measurements of magnetic field at a wide temperature range of 300K-4K. The system is based on 8 AMR sensors and allows for control of the magnetic environment in a dilution refrigerator during the cool down of a superconducting processor. With a low noise signal processing electronics and a special sensor saturation circuit, a magnetic induction resolution below of 1 nT was achieved.

  2. A miniature discriminating monitor for tritiated water vapour

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, R.A.H.; Ravazzani, A.; Pacenti, P. [European Commission, JRC, Institute for Advanced Material, Ispra, Vatican City State, Holy See (Italy); Campi, F. [Nuclear Engineering Dept., Polytechnic of Milan (Italy)

    1998-07-01

    In detecting tritium in air (or other gas) for worker safety, it is important to discriminate between tritiated water vapour and elemental tritium, because the first is much more easily absorbed in the lungs. We haveinvented (patent pending) an innovative discriminating monitor which works better than existing designs, and is much smaller. The air (or other sample gas) passes over a large surface area of solid scintillator, which is surface-treated to make it hygroscopic. Tritiated water vapour in the air exchanges continuously, rapidly and reversibly with the water in the thin hygroscopic layer; which is of the order of 1 micron thick. The beta-emissions from tritium in the hygroscopic layer hit the solid scintillator, causing flashes of light that are detected by a photomultiplier. The new discriminating monitor for tritiated species in air offers superior performance to existing discriminating monitors, and is much smaller. It is planned to develop a portable version which could serve as a personal tritium monitor. (authors)

  3. Droplet spectrum at different vapour pressure deficits1

    Directory of Open Access Journals (Sweden)

    Christiam Felipe Silva Maciel

    Full Text Available ABSTRACT An efficient pesticides spraying depends a lot in psychrometric conditions, mainly if it is using fine droplets, once climatic conditions may cause droplets evaporation and consequent financial loss to the farmer. Thus, the aim of this work was to determine the droplet spectrum depending on the vapour pressure deficits. The work was carried out inside of a climate chamber to obtain the vapour pressure deficits (VPDair. The laser particle analyzer, model Spraytech, was used to determine the droplet spectrum, and the experiment was conducted in factorial scheme 5 x 20, consisted of five working pressures (100; 200; 300; 400 and 500 kPa and twenty VPDair (2.3; 3.2; 4.2; 5.6; 7.0; 7.4; 9.5; 11.7; 12.7; 15.8; 16.4; 16.9; 21.2; 22.1; 22.2; 28.1; 29.7; 36.9 39.4 e 51.6 hPa, in completely randomized design with five replications. There is influence of VPDair on droplet spectrum behavior. Increasing the VPDair reduces the percentage of sprayed volume comprised by droplets with diameter between 100 and 200 µm, between 200 and 300 µm, between 300 and 400 µm, between 400 and 500 µm and between 500 and 600 µm. Increasing VPDair increases the VMD, Dv90, SPAN and the percentage of sprayed volume comprised by droplets larger than 600 µm.

  4. Study of water vapour adsorption kinetics on aluminium oxide materials

    Science.gov (United States)

    Livanova, Alesya; Meshcheryakov, Evgeniy; Reshetnikov, Sergey; Kurzina, Irina

    2017-11-01

    Adsorbents on the basis of active aluminum oxide are still of demand on the adsorbent-driers market. Despite comprehensive research of alumina adsorbents, and currently is an urgent task to improve their various characteristics, and especially the task of increasing the sorption capacity. In the present work kinetics of the processes of water vapours' adsorption at room temperature on the surface of desiccant samples has been studied. It was obtained on the basis of bayerite and pseudoboehmite experimentally. The samples of pseudoboehmite modified with sodium and potassium ions were taken as study objects. The influence of an adsorbent's grain size on the kinetics of water vapours' adsorption was studied. The 0.125-0.25 mm and 0.5-1.0 mm fractions of this sample were used. It has been revealed that the saturation water vapor fine powder (0.125-0.25 mm) is almost twofold faster in comparison with the sample of fraction 0.5-1.0 mm due to the decrease in diffusion resistance in the pores of the samples when moving from the sample of larger fraction to the fine-dispersed sample. It has been established that the adsorption capacity of the pseudoboehmite samples, modified by alkaline ions, is higher by ˜40 %, than for the original samples on the basis of bayerite and pseudoboehmite.

  5. Thermally decarboxylated sodium bicarbonate: Interactions with water vapour, calorimetric study

    Directory of Open Access Journals (Sweden)

    Natalia Volkova

    2013-06-01

    Full Text Available Isothermal titration calorimetry (ITC was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate (NaHCO3. The decarboxylation degree of the samples was varied from 3% to 35% and the humidity range was 54–100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% (RHo, was determined as the inflection point on a plot of the mean−ΔHkJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake (m was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider’s salt on the bicarbonate surface is proposed for humidities below RHo. Keywords: Isothermal titration calorimetry, Sodium bicarbonate, Sodium carbonate, Trona salt, Wegscheider’s salt, Enthalpy, Relative humidity, Pyrolytic decarboxylation

  6. Helium refrigeration system for hydrogen liquefaction applications

    Science.gov (United States)

    Nair, J. Kumar, Sr.; Menon, RS; Goyal, M.; Ansari, NA; Chakravarty, A.; Joemon, V.

    2017-02-01

    Liquid hydrogen around 20 K is used as cold moderator for generating “cold neutron beam” in nuclear research reactors. A cryogenic helium refrigeration system is the core upon which such hydrogen liquefaction applications are built. A thermodynamic process based on reversed Brayton cycle with two stage expansion using high speed cryogenic turboexpanders (TEX) along with a pair of compact high effectiveness process heat exchangers (HX), is well suited for such applications. An existing helium refrigeration system, which had earlier demonstrated a refrigeration capacity of 470 W at around 20 K, is modified based on past operational experiences and newer application requirements. Modifications include addition of a new heat exchanger to simulate cryogenic process load and two other heat exchangers for controlling the temperatures of helium streams leading out to the application system. To incorporate these changes, cryogenic piping inside the cold box is suitably modified. This paper presents process simulation, sizing of new heat exchangers as well as fabrication aspects of the modified cryogenic process piping.

  7. Fault detection and diagnosis for refrigerator from compressor sensor

    Science.gov (United States)

    Keres, Stephen L.; Gomes, Alberto Regio; Litch, Andrew D.

    2016-12-06

    A refrigerator, a sealed refrigerant system, and method are provided where the refrigerator includes at least a refrigerated compartment and a sealed refrigerant system including an evaporator, a compressor, a condenser, a controller, an evaporator fan, and a condenser fan. The method includes monitoring a frequency of the compressor, and identifying a fault condition in the at least one component of the refrigerant sealed system in response to the compressor frequency. The method may further comprise calculating a compressor frequency rate based upon the rate of change of the compressor frequency, wherein a fault in the condenser fan is identified if the compressor frequency rate is positive and exceeds a condenser fan fault threshold rate, and wherein a fault in the evaporator fan is identified if the compressor frequency rate is negative and exceeds an evaporator fan fault threshold rate.

  8. Magnetic Refrigeration – an Energy Efficient Technology for the Future

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden; Smith, Anders; Pryds, Nini

    2009-01-01

    . This magnetocaloric effect is inherent to all magnetic materials, but manifests itself stronger in some materials. The thermodynamically reversible nature of the magnetocaloric effect holds out the promise of a more energy efficient method of refrigeration compared to conventional compressor technology. Coupling......Magnetic refrigeration is an emerging technology that has the potential to significantly reduce the energy consumption in the refrigeration sector. The technology relies on the heating and cooling of magnetic materials upon the application and removal of a magnetic field, respectively...... this with an absence of ozone depleting and greenhouse contributing gasses gives magnetic refrigeration the potential to become an environmentally sustainable technology. The magnetic refrigeration group at Risø DTU aims to demonstrate the technology in a prototype magnetic refrigeration device. Our work spans a wide...

  9. Development of a high efficiency, automatic defrosting refrigerator-freezer

    Science.gov (United States)

    Topping, R. F.; Lee, W. D.

    The development of an energy efficient refrigerator freezer prototype to accelerate the commercialization of residential, high efficiency refrigerator freezers is described. A computer model developed to simulate the cabinet and refrigeration unit performance was used to evaluate alternative designs and optimize the cabinet insulation as well as the refrigeration component integration. Placement of polyurethane foam insulation in the cabinet and thicker insulation in the doors were used to reduce the closed door heat load of the prototype. Modifications to the evaporator system provide automatic frost-free operation with a significantly reduced defrost energy requirement. Resulting higher moisture levels in the refrigerator compartment enhance fresh food storage. A dual control system, different from most models which use only one active control, provides precise temperature regulation in both the freezer and refrigerator compartments.

  10. Development of a battery-free solar refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Ewert, Michael K; Bergeron, David J. III [Houston, TX (United States)

    2000-07-01

    Recent technology developments and a systems engineering design approach have led to the development of a practical battery-free solar refrigerator as a spin-off of NASA's aerospace refrigeration research. Off-grid refrigeration is a good application of solar photovoltaic (PV) power thermal storage is incorporated and a direct connection is made between the cooling system and the PV panel. This was accomplished by integrating water as a phase-change material into a well-insulated refrigerator cabinet and by developing a microprocessor-based control system that allows direct connection of a PV panel to a variable-speed compressor. This second innovation also allowed peak power-point tracking from the PV panel and elimination of batteries from the system. First a laboratory unit was developed to prove the concept and then a commercial unit was produced and deployed in a field test. The laboratory unit was used to test many different configurations including thermoelectric., Stirling and vapor compression cooling systems. The final configuration used a vapor compression cooling cycle, vacuum insulation, a passive condenser, and integral evaporator/thermal storage tank, two 77 watt PV panels, and the novel controller mentioned above. The system's only moving part was the variable-speed BD35 compressor made by Danfoss. The 365 liter cabinet stayed cold with as a little as 274 watt-hours per day average PV power. Battery-free testing was conducted for several months with very good results. The amount of thermal storage, size of compressor, and power of PV panels connected can all be adjusted to optimize the design for a given application and climate. In the commercial unit, vacuum insulation and the stainless steel thermal storage tank were not used in order to reduce cost and make the technology commercially viable. This unit started with a 142 liter, mass-produced chest freezer cabinet that had the evaporator integrated into its inner walls. Its compressor

  11. Compressor calorimeter performance of refrigerant blends: Comparative methods and results for a refrigerator/freezer application

    Science.gov (United States)

    Rice, C. K.; Sand, J. R.

    1993-01-01

    A protocol was developed to define calorimeter operating pressures for nonazeotropic refrigerant mixtures (NARM's) which corresponded with the saturated evaporator and condenser temperatures commonly used for pure refrigerants. Compressor calorimeter results were obtained using this equivalent-mean-temperature (EMT) approach and a generally applied Association of Home Appliance Manufacturers (AHAM) procedure at conditions characteristic of a domestic refrigerator-freezer application. Tests with R-12 and two NARM's indicate that compressor volumetric and isentropic efficiencies are nearly the same for refrigerants with similar capacities and pressure ratios. The liquid-line temperature conditions specified in the AHAM calorimeter rating procedure for refrigerator-freezer compressors were found to preferentially derate NARM performance relative to R-12. Conversion of calorimeter data taken with a fixed liquid-line temperature to a uniform minimal level of condenser subcooling is recommended as a fairer procedure when NARM's are involved. Compressor energy-efficiency-ratio (EER) and capacity data measured as a result of the EMT approach were compared to system performance calculated using an equivalent heat exchanger loading (EHXL) protocol based on a Lorenz-Meutzner (L-M) refrigerator-freezer modeling program. The EHXL protocol was used to transform the calorimeter results into a more relevant representation of potential L-M cycle performance. The EMT method used to set up the calorimeter tests and the AHAM liquid-line conditions combined to significantly understate the cycle potential of NARM's relative to that predicted at the more appropriate EHXL conditions. Compressor conditions representative of larger heat exchanger sizes were also found to give a smaller L-M cycle advantage relative to R-12.

  12. Hydrophilic structures for condensation management in refrigerator appliances

    Science.gov (United States)

    Kuehl, Steven John; Vonderhaar, John J; Wu, Guolian; Wu, Mianxue

    2014-10-21

    A refrigerator appliance that includes a freezer compartment having a freezer compartment door, and a refrigeration compartment having at least one refrigeration compartment door. The appliance further includes a mullion with an exterior surface. The mullion divides the compartments and the exterior surface directs condensation toward a transfer point. The appliance may also include a cabinet that houses the compartments and has two sides, each with an exterior surface. Further, at least one exterior surface directs condensation toward a transfer point.

  13. New Copper-based Heat Exchangers for Alternative Refrigerants

    OpenAIRE

    Shabtay, Yoram; Black, John; Kraft, Frank

    2014-01-01

    The ongoing global effort to replace current refrigerants with zero Ozone Depletion Potential (ODP) and virtually zero Global Warming Potential (GWP) refrigerants has important implications for heat exchangers, air conditioning system design, and the materials choices in these designs. Natural refrigerants with higher flammability, CO2, new HFC blends, and new HFO’s each place different requirements on the heat exchanger design, whether it be for higher equipment efficiency, to reduce refrige...

  14. Evaluating alternative refrigerants for the room air conditioner market

    OpenAIRE

    Back, Izabelle; Dunberger, Lars

    2015-01-01

    This study aimed to facilitate evaluation of alternative refrigerants for the air conditioner market. In order to achieve this target, two objectives were set. The first being the identification of alternative refrigerant with regard to regulations and trends. The second being enabling of thermodynamic evaluation of refrigerants for single components in air conditioners via design and installation of a test rig. A literature review was conducted to investigate the regulations, standards and t...

  15. Refrigeration arrangement and methods for reducing charge migration

    Science.gov (United States)

    Litch, Andrew D.; Wu, Guolian

    2017-04-11

    A refrigerator appliance including a refrigerant circuit between a condenser, an evaporator, and a compressor that includes two conduits and pressure reducing devices arranged in parallel between the evaporator and the condenser. The appliance also includes a valve system to direct refrigerant through one, both or none of the conduits and pressure reducing devices, and a heat exchanging member in thermal contact with either one pressure reducing device, or one conduit between the pressure reducing device and the valve system.

  16. Refrigeration needs for sustainable preservation of horticultural products

    OpenAIRE

    Sousa, A.R.; Juliao, M.; Miguel, Maria Graça; Antunes, Maria Dulce; Panagopoulos, Thomas

    2011-01-01

    Fresh horticultural products are highly perishable and need refrigeration for further preservation. Refrigeration needs energy consumption with consequent economical cost and damage for the environment. The objective of the present work was to use efficiently the refrigeration according to the product needs and time for consumption. Salicornia ramosissima and Sarcocornia perennis fresh branch tips, which are used for fresh salads, were stored at 1, 4 and 9 °C for up to 21 days. In both specie...

  17. Methods for estimating the vapour pressure of organic chemicals; Application to five pesticides

    NARCIS (Netherlands)

    Leistra, M.

    2011-01-01

    When studying and modelling the volatilisation of pesticides from crops, their vapour pressure is an essential property. In the critical evaluation of vapour pressures stated by various sources, problems were encountered. Therefore, an inventory was made of readily-usable methods for estimating

  18. Vapour phase corrosion inhibitors from South African renewable resources and their evaluation

    CSIR Research Space (South Africa)

    Vuorinen, E

    2006-02-01

    Full Text Available A vapour-phase corrosion inhibitor (VCI) needs to be a volatile compound or a mixture of compounds. It reaches the surfaces that need to be protected from corrosion via the vapour phase and forms a relatively stable bond at the interface...

  19. Utility of DMSP-SSM/I for integrated water vapour over the Indian seas

    Indian Academy of Sciences (India)

    Recent algorithms for Special Sensor Microwave/Imager (DMSP-SSM/I) satellite data are used for estimating integrated water vapour over the Indian seas. ... On the basis of this algorithm, distribution of integrated water vapour is determined during the monsoon depression (22nd{27th July, 1992) that formed over the Bay of ...

  20. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    DEFF Research Database (Denmark)

    Fumagalli, F; Kylian, O; Amato, Letizia

    2012-01-01

    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can...... vapour plasma process are discussed for practical applications in medical devices decontamination....

  1. Ethanol vapour sensing properties of screen printed WO3 thick films

    Indian Academy of Sciences (India)

    This paper presents ethanol vapour sensing properties of WO3 thick films. In this work, the WO3 thick films were prepared by standard screen-printing method. These films were characterized by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The ethanol vapour sensing properties of these ...

  2. New Method of Vapour Discrimination Using the Thickness Shear Mode (TSM Resonator

    Directory of Open Access Journals (Sweden)

    J. Siddiqi

    2003-06-01

    Full Text Available The Impedance analysis technique complimented with curve fitting software was used to monitor changes in film properties of Thickness Shear Mode (TSM resonator on vapour exposure. The approach demonstrates how sensor selectivity can be achieved through unique changes in film viscosity caused by organic vapour adsorption.

  3. Utility of DMSP-SSM/I for integrated water vapour over the Indian seas

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging Solutions)

    Recent algorithms for Special Sensor Microwave/Imager (DMSP-SSM/I) satellite data are used for estimating integrated water vapour over the Indian seas. Integrated water vapour obtained from these algorithms is compared with that derived from radiosonde observations at Minicoy and Port. Blair islands. Algorithm-3 of ...

  4. Computer modeling of the vapor compression cycle with constant flow area expansion device

    Science.gov (United States)

    Domanski, P.; Didion, D.

    1983-05-01

    An analysis of the vapor compression cycle and the main components of an air source heat pump during steady state operator was performed with emphasis on fundamental phenomena taking place between key locations in the refrigerant system. The basis of the general heat pump model formulation is the logic which links the analytical models of heat pump components together in a format requiring an iterative solution of refrigerant pressure, enthalpy and mass balances. The modeling effort emphasis was on the local thermodynamic phenomena which were described by fundamental heat transfer equations and equation of state relationships among material properties.

  5. Refrigeration processes a practical handbook on the physical properties of refrigerants and their applications

    CERN Document Server

    Meacock, H M

    1979-01-01

    A comprehensive applications-oriented treatment of the subject in two parts. The first part forms a useful introduction to basic principles dealing with the definitions of the physical properties and outlines the method of their calculation. The second part is devoted to calculated data on a range of refrigerants by means of extensive tables and diagrams. The treatment takes the form of a data sheet, one for each of about thirty refrigerants; this data sheet gives the essential information from which close approximations of pressure, temperature, volume and enthalpy can be made for any predict

  6. Refrigeration Playbook. Heat Reclaim; Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Chuck [CTA Architects Engineers, Boise, ID (United States); Nelson, Eric [CTA Architects Engineers, Boise, ID (United States); Armer, James [CTA Architects Engineers, Boise, ID (United States); Johnson, Tim [CTA Architects Engineers, Boise, ID (United States); Hirsch, Adam [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-03-01

    The purpose of this playbook and accompanying spreadsheets is to generalize the detailed CBP analysis and to put tools in the hands of experienced refrigeration designers to evaluate multiple applications of refrigeration waste heat reclaim across the United States. Supermarkets with large portfolios of similar buildings can use these tools to assess the impact of large-scale implementation of heat reclaim systems. In addition, the playbook provides best practices for implementing heat reclaim systems to achieve the best long-term performance possible. It includes guidance on operations and maintenance as well as measurement and verification.

  7. Model based control of refrigeration systems

    Energy Technology Data Exchange (ETDEWEB)

    Sloth Larsen, L.F.

    2005-11-15

    The subject for this Ph.D. thesis is model based control of refrigeration systems. Model based control covers a variety of different types of controls, that incorporates mathematical models. In this thesis the main subject therefore has been restricted to deal with system optimizing control. The optimizing control is divided into two layers, where the system oriented top layers deals with set-point optimizing control and the lower layer deals with dynamical optimizing control in the subsystems. The thesis has two main contributions, i.e. a novel approach for set-point optimization and a novel approach for desynchronization based on dynamical optimization. The focus in the development of the proposed set-point optimizing control has been on deriving a simple and general method, that with ease can be applied on various compositions of the same class of systems, such as refrigeration systems. The method is based on a set of parameter depended static equations describing the considered process. By adapting the parameters to the given process, predict the steady state and computing a steady state gradient of the cost function, the process can be driven continuously towards zero gradient, i.e. the optimum (if the cost function is convex). The method furthermore deals with system constrains by introducing barrier functions, hereby the best possible performance taking the given constrains in to account can be obtained, e.g. under extreme operational conditions. The proposed method has been applied on a test refrigeration system, placed at Aalborg University, for minimization of the energy consumption. Here it was proved that by using general static parameter depended system equations it was possible drive the set-points close to the optimum and thus reduce the power consumption with up to 20%. In the dynamical optimizing layer the idea is to optimize the operation of the subsystem or the groupings of subsystems, that limits the obtainable system performance. In systems

  8. Spacecraft-borne long life cryogenic refrigeration: Status and trends

    Science.gov (United States)

    Johnson, A. L.

    1983-01-01

    The status of cryogenic refrigerator development intended for, or possibly applicable to, long life spacecraft-borne application is reviewed. Based on these efforts, the general development trends are identified. Using currently projected technology needs, the various trends are compared and evaluated. The linear drive, non-contacting bearing Stirling cycle refrigerator concept appears to be the best current approach that will meet the technology projection requirements for spacecraft-borne cryogenic refrigerators. However, a multiply redundant set of lightweight, moderate life, moderate reliability Stirling cycle cryogenic refrigerators using high-speed linear drive and sliding contact bearings may possibly suffice.

  9. Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators (ADRs) in space applications, it is desirable to have very light weight, small diameter, high current density...

  10. Transitioning to Low-GWP Alternatives in Commercial Refrigeration

    Science.gov (United States)

    This fact sheet provides information on low-GWP alternatives in commercial refrigeration. It discusses HFC alternatives, market trends, challenges to market entry for alternatives, and potential solutions.

  11. Reasearch and Evaluation of Electromagnetic Fields of Refrigerators

    Directory of Open Access Journals (Sweden)

    Pranas Baltrėnas

    2013-12-01

    Full Text Available The use of refrigerators causes the occurence of electromagnetic fields that are invisible and intangible, which therefore makes difficulties in protecting ourselves from them. A refrigerator is an irreplaceable item in domestic household and thus can be hardly ignored by a modern way of human life. In order to preserve the characteristics of products, the refrigerator must operate continuously (24 hrs a day, regardless of the time of the year. This results in a huge increase in electricity consumption, which leads to energy consumption related pollution of the environment emitting CO2 gas. On these grounds, it is necessary to assess electromagnetic fields created by the refrigerator. Studies on electromagnetic fields produced by refrigerators were conducted in domestic premises where people spent a significant part of the day. For comparison purposes, five different power refrigerators were chosen (1 – 0.20 kW; 2 – 0.25 kW; 3 – 0.30 kW; 4 – 0.35 kW; 5 – 0.40 kW. The obtained results, according to the parameters of their electromagnetic fields, were presented in graphs and charts and showed that the values of electric and magnetic intensity of refrigerators depended on the distance and the power of the refrigerator. The conducted research also disclosed that none of tested refrigerators exceeded the permissible limits of electromagnetic fields.Article in Lithuanian

  12. Performance data and optimisation of a Stirling refrigerator at temperatures below -30 C; Leistungsdaten und Optimierung einer Stirling-Kaeltemaschine bei Temperaturen der Kaeltebereitstellung unterhalb von -30 C

    Energy Technology Data Exchange (ETDEWEB)

    Mai, M.; Schikora, H.; Steimle, F. [Inst. fuer Angewandte Thermodynamik und Klimatechnik (IATK), Univ. GH Essen, Essen (Germany)

    2002-07-01

    In a BMWi-funded research project, a Stirling refrigerator was developed and tested at temperatures below -30 C. After some initial disappointments, optimisations were made, and the final product is fully competitive with conventional cold vapour refrigerators. The refrigerator is based on the Solo 161 Stirling engine, which is renowned for its high reliability in more than 100,000 hours of operation. [German] Im Rahmen eines BMWi-gefoerderten Forschungsvorhabens wurde eine Stirling-Kaeltemaschine entwickelt und bei Temperaturen der Kaeltebereitstellung unterhalb von -30 C experimentell untersucht. Diese auf dem Solo 161 Stirling-Motor basierende Kaeltemaschine erreichte jedoch zunaechst nicht die aufgrund von Simulationsrechnungen zu erwartenden Leistungsdaten. Durch die Analyse der Messwerte und deren Vergleich mit den Simulationsdaten konnten die Schwachstellen der ersten Konstruktion lokalisiert werden. Zahlreiche Optimierungsmassnahmen haben zu erheblichen Verbesserungen der Leistungsdaten gefuehrt. Der Guetegrad der entwickelten Stirling-Kaeltemaschine konnte um bis zu 30% gesteigert werden. So konnte erreicht werden, dass die Stirling-Kaeltemaschine bei einer Temperatur der Kaelteerzeugung von -40 C durchaus konkurrenzfaehig zu herkoemmlichen Kaltdampfkaeltemaschinen sein kann. Da die gesamte Grundmaschine vom Solo 161 Stirling-Motor uebernommen wurde, der seine Zuverlaessigkeit mit einer akkumulierten Laufzeit von ueber 100.000 Stunden bewiesen hat, kann auch bei der Kaeltemaschine von einer hohen Zuverlaessigkeit ausgegangen werden. (orig.)

  13. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    DEFF Research Database (Denmark)

    El-Khattam, Amira; Andersen, Mie Them; Kielsgaard Hansen, Kurt

    2014-01-01

    it is essential to know how much influence a surface treatment has on the water vapour transport. Traditionally, there has been most focus on paints that affect the permeability as little as possible. However, sometimes water vapour resistance is desirable. Especially, this is relevant in existing buildings...... on the ceiling e.g. as an ordinary paint. This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface...... treatments. The surface treatments were glass felt or glass fibre cloth with different types of paints or just paint. The paint types were acrylic paint and silicate paint. The results show that the paint type has high influence on the water vapour resistance while the underlay i.e. glass felt or glass fibre...

  14. Stratospheric water vapour as tracer for Vortex filamentation in the Arctic winter 2002/2003

    Directory of Open Access Journals (Sweden)

    M. Müller

    2003-01-01

    Full Text Available Balloon-borne frost point hygrometers measured three high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen during winter 2002/2003. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. The water vapour sounding on 11 February 2003 was obtained within the vortex edge region of the lower stratosphere. Here, a significant reduction of water vapour mixing ratio was observed between 16 and 19 km. The stratospheric temperatures indicate that this dehydration was not caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. Ozone observations on this day indicate a large scale movement of the polar vortex and show laminae in the same altitude range as the water vapour profile. The link between the observed water vapour reduction and filaments in the vortex edge region is indicated in the results of the semi-lagrangian advection model MIMOSA, which show that adjacent filaments of polar and mid latitude air can be identified above the Spitsbergen region. A vertical cross-section produced by the MIMOSA model reveals that the water vapour sonde flew through polar air in the lowest part of the stratosphere below 425 K, then passed through filaments of mid latitude air with lower water vapour concentrations, before it finally entered the polar vortex above 450 K. These results indicate that on 11 February 2003 the frost point hygrometer measured different water vapour concentrations as the sonde detected air with different origins. Instead of being linked to dehydration due to PSC particle sedimentation, the local reduction in the stratospheric water vapour profile was in this case caused by dynamical processes in the polar stratosphere.

  15. Next Generation Refrigeration Lubricants for Low Global Warming Potential/Low Ozone Depleting Refrigeration and Air Conditioning Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hessell, Edward

    2013-12-31

    The goal of this project is to develop and test new synthetic lubricants that possess high compatibility with new low ozone depleting (LOD) and low global warming potential (LGWP) refrigerants and offer improved lubricity and wear protection over current lubricant technologies. The improved compatibility of the lubricants with the refrigerants, along with improved lubricating properties, will resulted in lower energy consumption and longer service life of the refrigeration systems used in residential, commercial and industrial heating, ventilating and air-conditioning (HVAC) and refrigeration equipment.

  16. Hierarchically arranged helical fibre actuators driven by solvents and vapours

    Science.gov (United States)

    Chen, Peining; Xu, Yifan; He, Sisi; Sun, Xuemei; Pan, Shaowu; Deng, Jue; Chen, Daoyong; Peng, Huisheng

    2015-12-01

    Mechanical responsiveness in many plants is produced by helical organizations of cellulose microfibrils. However, simple mimicry of these naturally occurring helical structures does not produce artificial materials with the desired tunable actuations. Here, we show that actuating fibres that respond to solvent and vapour stimuli can be created through the hierarchical and helical assembly of aligned carbon nanotubes. Primary fibres consisting of helical assemblies of multiwalled carbon nanotubes are twisted together to form the helical actuating fibres. The nanoscale gaps between the nanotubes and micrometre-scale gaps among the primary fibres contribute to the rapid response and large actuation stroke of the actuating fibres. The compact coils allow the actuating fibre to rotate reversibly. We show that these fibres, which are lightweight, flexible and strong, are suitable for a variety of applications such as energy-harvesting generators, deformable sensing springs and smart textiles.

  17. Atmospheric pressure vapour phase decomposition: a proof of principle.

    Science.gov (United States)

    Cinosi, Amedeo; Andriollo, Nunzio; Tibaldi, Francesca; Monticelli, Damiano

    2012-11-15

    In the present work we demonstrated that the digestion of difficult matrices (high boiling petrochemical fractions and distillation bottoms) can be achieved by oxidation with nitric acid vapours at atmospheric pressure employing simple laboratory glassware. The application of this procedure as a digestion method prior to Total Reflection X-Ray Fluorescence (TXRF) is presented, although the employment of other detection techniques may be foreseen. The method ensured a fast, less than half an hour, treatment time and detection limits in the range 20-100 μg/kg for As, Bi, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Zn, whereas higher values were obtained for Ba, Ca, K, P, Rh, Ti and V (0.3-3 mg/kg). The potentialities and limitations of this procedure were discussed: the application to a broad range of matrices may be foreseen. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. The Chemical Vapour Deposition of Tantalum - in long narrow channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki

    concentrations in order to document the effects of these properties on the tantalum deposition rates. A kinetic model is developed upon the foundation of a Computational Fluid Dynamics (CFD) and Thermal model in order to broaden the understanding of the process and to identify the key control parameters...... mechanism of reaction, TaCl3 is found to have a lot of relevance such that it is the main precursor to the surface reaction and that the overall deposition rates follow its abundance. An experiment with a real plate heat exchanger is also done and the corresponding model implemented with satisfactory...... use as a construction material for process equipment, with the cheaper alternative being the construction of equipment from steel and then protecting it with a thin but efficacious layer of tantalum. Chemical Vapour Deposition (CVD) is chosen as the most effective process to apply thin corrosion...

  19. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  20. Thermoluminescence characterisation of chemical vapour deposited diamond films

    CERN Document Server

    Mazzocchi, S; Bucciolini, M; Cuttone, G; Pini, S; Sabini, M G; Sciortino, S

    2002-01-01

    The thermoluminescence (TL) characteristics of a set of six chemical vapour deposited diamond films have been studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterisation has been performed by means of Raman spectroscopy. Their TL responses have been tested with radiotherapy beams ( sup 6 sup 0 Co photons, photons and electrons from a linear accelerator (Linac), 26 MeV protons from a TANDEM accelerator) in the dose range 0.1-7 Gy. The dosimetric characterisation has yielded a very good reproducibility, a very low dependence of the TL response on the type of particle and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the diamond samples compares favourably with that of standard TLD100 dosimeters.

  1. Chemical Vapour Deposition of Gas Sensitive Metal Oxides

    Directory of Open Access Journals (Sweden)

    Stella Vallejos

    2016-03-01

    Full Text Available This article presents a review of recent research efforts and developments for the fabrication of metal-oxide gas sensors using chemical vapour deposition (CVD, presenting its potential advantages as a materials synthesis technique for gas sensors along with a discussion of their sensing performance. Thin films typically have poorer gas sensing performance compared to traditional screen printed equivalents, attributed to reduced porosity, but the ability to integrate materials directly with the sensor platform provides important process benefits compared to competing synthetic techniques. We conclude that these advantages are likely to drive increased interest in the use of CVD for gas sensor materials over the next decade, whilst the ability to manipulate deposition conditions to alter microstructure can help mitigate the potentially reduced performance in thin films, hence the current prospects for use of CVD in this field look excellent.

  2. Effects of Acoustic and Fluid Dynamic Interactions in Resonators: Applications in Thermoacoustic Refrigeration

    Science.gov (United States)

    Antao, Dion Savio

    of the systems over a wide range of operating conditions helped to better understand the factors that govern and affect the performance of the PTR. The operating frequency of the linear motor driving the PTR affected the systems' performance the most. Other parameters that resulted in performance variations were the mean operating pressure, the pressure amplitude output from the linear motor, and the geometry of the inertance tube. The effect of the inertance tube's geometry was controlled by a single parameter labeled the "inertance". External/ambient conditions affected the performance of the cryocoolers too. To prevent the influence of the ambient conditions on the performance, a vacuum chamber was fabricated to isolate the low temperature regions of the PTR from the variable ambient atmosphere. The experiments provided important information and guidelines for the simulation studies of the PTR that were carried out concurrently. A time-dependent high fidelity computational fluid dynamic model of the entire PTR system was developed to gain a better understanding of internal interactions between the refrigerant fluid and the porous heat-exchangers in its various components and to facilitate better design of PTR systems based on the knowledge gained. The compressible forms of the conservation of mass, momentum and energy equations are solved in the gas and porous media (appropriate estimation of fluid dynamics in heat-exchangers) regions. The heat transfer in the porous regions is governed by a thermal non-equilibrium heat transfer model that calculates a separate gas and solid temperature and accounts for heat transfer between the two. The numerical model was validated using both temporal and quasi-steady state results obtained from the experimental studies. The validated model was applied to study the effects of different operating parameters (frequency, pressure and geometry of the components) on the PTR's performance. The simulations revealed interesting steady

  3. Evaluating the virucidal efficacy of hydrogen peroxide vapour.

    Science.gov (United States)

    Goyal, S M; Chander, Y; Yezli, S; Otter, J A

    2014-04-01

    Surface contamination has been implicated in the transmission of certain viruses, and surface disinfection can be an effective measure to interrupt the spread of these agents. To evaluate the in-vitro efficacy of hydrogen peroxide vapour (HPV), a vapour-phase disinfection method, for the inactivation of a number of structurally distinct viruses of importance in the healthcare, veterinary and public sectors. The viruses studied were: feline calicivirus (FCV, a norovirus surrogate); human adenovirus type 1; transmissible gastroenteritis coronavirus of pigs (TGEV, a severe acute respiratory syndrome coronavirus [SARS-CoV] surrogate); avian influenza virus (AIV); and swine influenza virus (SwIV). The viruses were dried on stainless steel discs in 20- or 40-μL aliquots and exposed to HPV produced by a Clarus L generator (Bioquell, Horsham, PA, USA) in a 0.2-m(3) environmental chamber. Three vaporized volumes of hydrogen peroxide were tested in triplicate for each virus: 25, 27 and 33 mL. No viable viruses were identified after HPV exposure at any of the vaporized volumes tested. HPV was virucidal (>4-log reduction) against FCV, adenovirus, TGEV and AIV at the lowest vaporized volume tested (25 mL). For SwIV, due to low virus titre on the control discs, >3.8-log reduction was shown for the 25-mL vaporized volume and >4-log reduction was shown for the 27-mL and 33-mL vaporized volumes. HPV was virucidal for structurally distinct viruses dried on surfaces, suggesting that HPV can be considered for the disinfection of virus-contaminated surfaces. Copyright © 2014 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  4. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix

    2014-06-22

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  5. Performance Monitoring in Supermarket Refrigeration Systems - Synchronisation of Refrigerated Display Cases

    DEFF Research Database (Denmark)

    Chen, Liang; Green, Torben; Sloth Larsen, Lars Finn

    2009-01-01

    . The conceptual validation of these methods has been by far illustrated through the use of typically simple academic examples. In this paper the hybrid systems is treated as a single directed topological space, and presents a refrigeration system as a benchmark that should be useful as a platform...

  6. New concept of refrigeration. ; Magnetic refrigeration. Goku teion gijutsu. ; Jiki reito wo chushin to shite

    Energy Technology Data Exchange (ETDEWEB)

    Ogiwara, H.; Nakagome, H. (Toshiba Corp., Tokyo (Japan))

    1990-07-05

    This paper explained the principle, construction and problems of magnetic refrigeration which is an advanced refrigerartion technique. When strong field is applied to a paramagnet from the outside, the paramagnet bocomes a state of low entropy, that is, arranged electron spin. Adiabatic elimination of magnetic field deprives heat of lattice vibration of the paramagnet, returns it to the the entropy of electron spin without magnetic field, resulting itself to lower temperature state. This is the principle of adiabatic demaganetization by which a cycle to refrigerate and exhaust heat by a thermal switch can be constructed. But since the temperature range to which a paramagnet can exhibit the remarkable effect is limited, major problems are the selection of optimal paramagnet and how to get the AC or pulse magnetic field, although the practically necessary field may be obtained by a superconducting magnet. National Research Institute of Metals in Science and Technology Agency manufactured trially a stationary type magnetic refrigerator, of which maximum refrigerating capability was 100mW at 2K and minimum reachable temperature was 1.5K. 9 refs., 13 figs.

  7. PERFORMANCE OF A TWO-CYCLE REFRIGERATOR/FREEZER USING HFC REFRIGERANTS

    Science.gov (United States)

    A two-cycle 18 ft3 (0.51 m3) refrigerator/freezer (R/F) was tested utilizing American National Standards Institute (ANSI)/AHAM (1988) standards for energy consumption testing. A 34.9% energy consumption reduction was realized. This work presents a proven method of reducing the ...

  8. General RMP Guidance - Appendix E: Supplemental Risk Management Program Guidance for Ammonia Refrigeration Facilities

    Science.gov (United States)

    Additional information for food processors, food distributors, refrigerated warehouses, and any other facility with ammonia refrigeration system. Includes guidance on exemptions, threshold quantity, offsite consequence analysis.

  9. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Rune Hansen, Esben; Srinivasa Rao, S.; Tiedemann, Peter

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1......-2 bits per node. Empirical results for our compression technique are presented, including comparisons with previously introduced techniques, showing that the new technique dominate on all tested instances....

  10. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Hansen, Esben Rune; Satti, Srinivasa Rao; Tiedemann, Peter

    2008-01-01

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1......-2 bits per node. Empirical results for our compression technique are presented, including comparisons with previously introduced techniques, showing that the new technique dominate on all tested instances...

  11. Hyperspectral data compression

    CERN Document Server

    Motta, Giovanni; Storer, James A

    2006-01-01

    Provides a survey of results in the field of compression of remote sensed 3D data, with a particular interest in hyperspectral imagery. This work covers topics such as compression architecture, lossless compression, lossy techniques, and more. It also describes a lossless algorithm based on vector quantization.

  12. Toward High Performance in Industrial Refrigeration Systems

    DEFF Research Database (Denmark)

    Thybo, C.; Izadi-Zamanabadi, Roozbeh; Niemann, H.

    2002-01-01

    Achieving high performance in complex industrial systems requires information manipulation at different system levels. The paper shows how different models of same subsystems, but using different quality of information/data, are used for fault diagnosis as well as robust control design in industr......Achieving high performance in complex industrial systems requires information manipulation at different system levels. The paper shows how different models of same subsystems, but using different quality of information/data, are used for fault diagnosis as well as robust control design...... in industrial refrigeration systems....

  13. Towards High Performance in Industrial Refrigeration Systems

    DEFF Research Database (Denmark)

    Thybo, C.; Izadi-Zamanabadi, Roozbeh; Niemann, H.

    2002-01-01

    Achieving high performance in complex industrial systems requires information manipulation at different system levels. The paper shows how different models of same subsystems, but using different quality of information/data, are used for fault diagnosis as well as robust control design in industr......Achieving high performance in complex industrial systems requires information manipulation at different system levels. The paper shows how different models of same subsystems, but using different quality of information/data, are used for fault diagnosis as well as robust control design...... in industrial refrigeration systems....

  14. Development of a novel rotary magnetic refrigerator

    DEFF Research Database (Denmark)

    Lozano, Jaime A.; Capovilla, Matheus S.; Trevizoli, Paulo V.

    2016-01-01

    with approximately 1.7 kg of gadolinium spheres (425-600 μm diameter) were placed in the magnetic gap. Two low-friction rotary valves were developed to synchronize the hydraulic and magnetic cycles. The valves were positioned at the hot end to avoid heat generation in the cold end. In this work, experimental results......A novel rotary magnetic refrigerator was designed and built at the Federal University of Santa Catarina (UFSC). The optimized magnetic circuit is a two-pole system in a rotor-stator configuration with high flux density regions of approximately 1 T. Eight pairs of stationary regenerator beds filled...

  15. Four-level refrigerator driven by photons

    Science.gov (United States)

    Wang, Jianhui; Lai, Yiming; Ye, Zhuolin; He, Jizhou; Ma, Yongli; Liao, Qinghong

    2015-05-01

    We propose a quantum absorption refrigerator driven by photons. The model uses a four-level system as its working substance and couples simultaneously to hot, cold, and solar heat reservoirs. Explicit expressions for the cooling power Q˙c and coefficient of performance (COP) ηCOP are derived, with the purpose of revealing and optimizing the performance of the device. Our model runs most efficiently under the tight coupling condition, and it is consistent with the third law of thermodynamics in the limit T →0 .

  16. Flow-synchronous field motion refrigeration

    Science.gov (United States)

    Hassen, Charles N.

    2017-08-22

    An improved method to manage the flow of heat in an active regenerator in a magnetocaloric or an electrocaloric heat-pump refrigeration system, in which heat exchange fluid moves synchronously with the motion of a magnetic or electric field. Only a portion of the length of the active regenerator bed is introduced to or removed from the field at one time, and the heat exchange fluid flows from the cold side toward the hot side while the magnetic or electric field moves along the active regenerator bed.

  17. GNSS-Derived Water Vapour for Riyadh from SOLA IGS Station

    Science.gov (United States)

    Maghrabi, Abdullrahman; Alothman, Abdulaziz; Fernandes, Rui; Aodah, Souad

    2017-04-01

    Water vapor is the most abundant and highly variable component of the important gases in the atmosphere. It influences many physical and thermodynamical processes in the atmosphere and plays an important role in the hydrological cycle and has effects on our climate and weather systems. Water vapour affects the electromagnetic radiation through the atmosphere, which is of significance in fields of astronomy, radar, communications and remote sensing. Precipitable water vapor (PWV) is the amount of water obtained if all the water vapor in the atmosphere were to be compressed to the point at which it condenses into liquid. PWV is difficult to measure adequately due to its variable distribution both spatially and temporally. Most of the current techniques (e.g., radiosondes or satellites) are only available at few locations and not continuously (few observations per day at most). However, in the last decades, GPS observations have been proven to accurately measure the ZTD (Zenith Tropospheric Delay) at high frequencies (normally every 5 minutes) above the station. This quantity can be converted to PWV if temperature and pressure is know at the station location. In early 2004, King Abdulaziz City for Science and Technology (KACST) established a GPS network for geodetic and geophysical applications to contribute to the International GNSS Service IGS. In this study, we will present the first PWV measurements obtained from Global Navigation Satellite System GNSS receiver at the Solar Village (SOLA), 60 km from Riyadh. GNSS observations for the period between 2004-2006 are used to study the daily and seasonal variations of ZTD, and consequently of PWV in SOLA. In addition, we also compare the GNSS-derived PWV with sunphotometer and radiosonde estimates at SOLA in order to evaluate the compatibility of these techniques in a dry climate as the one in Riyadh.

  18. Nonlinear Superheat Control of a Refrigeration Plant using Backstepping

    DEFF Research Database (Denmark)

    Rasmussen, Henrik

    2008-01-01

    This paper proposes a novel method for superheat and capacity control of refrigeration systems. The main idea is to control the superheat by the compressor speed and capacity by the refrigerant flow. A new low order nonlinear model of the evaporator is developed and used in a backstepping design...

  19. development of a dual purpose refrigeration system for domestic use

    African Journals Online (AJOL)

    user

    1a4: Vaporization / Refrigeration Effect air: Dry air eff: Effective cap: Capillary. DB: Dry Bulb Temperature. REF: REFACON t or T. Ref: Total Refrigerator Load. Nigerian Journal of Technology (NIJOTECH). Vol. 35, No. .... (907 kg) of water at 0 °C to ice at 0 °C over a period of 24 hours. vii. The cooling load of the machine was.

  20. Refrigeration and Cryogenics Specialist. J3ABR54530

    Science.gov (United States)

    Air Force Training Command, Sheppard AFB, TX.

    This document package contains an Air Force course used to train refrigeration and cryogenics specialists. The course is organized in six blocks designed for group instruction. The blocks cover the following topics: electrical principles; fundamentals of tubing and piping; metering devices, motor controls, domestic and commercial refrigeration;…

  1. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    Science.gov (United States)

    Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd.sub.0.54 Er.sub.0.46)AlNi alloys having a relatively constant .DELTA.Tmc over a wide temperature range.

  2. Closed Cycle Solar Refrigeration with the Calcium Chloride System ...

    African Journals Online (AJOL)

    A closed cycle solid absorption intermittent refrigerator, using CaC12 absorbent and NH3 refrigerant, was constructed and tested to obtain the instantaneous and cumulative available overall COP. The combined collector/absorber/generator unit had double glazing of 1.14 m2 exposed areas. The system was fitted with a ...

  3. improvement to the design of a solid absorption solar refrigerator

    African Journals Online (AJOL)

    user

    The paper presents the highlights of the design of an existing solid absorption solar refrigerator, using CaCl2 ... on the coupling of auxiliary heating systems to the solar powered refrigerator. A re-design of the ... Six collector tubes, having a perforated co-axial galvanised inner steel tube, were bonded to the plate at 152 mm.

  4. Use of glucose oxidase to improve refrigerated dough quality

    Science.gov (United States)

    Refrigerated dough encompasses a wide range of products including bread, rolls, pastries and pizza crust and is a very popular choice for consumers. Two of the largest problems that occur during refrigerated dough storage are dough syruping and loss of dough strength. The goal of this study was to e...

  5. Control and optimization of the refrigeration plant in a brewery

    DEFF Research Database (Denmark)

    Petersen, P.M; Qvale, Einar Bjørn

    1989-01-01

    The design and operation of a refrigeration plant in a brewery has been studied. The plant has been evaluated by using mathematical models of the components to simulate responses to real-life load variations. The study shows that the efficiency and economy of the actual refrigeration plant could...

  6. Profile: Department of Refrigeration and Heat Pump Technology

    NARCIS (Netherlands)

    Sluis, S.M. van der

    2000-01-01

    The activities in the fields of refrigeration and heatpumps are concentrated within TNO Environment, Energy and Process Innovation, Apeldoorn, and specifically within the Department of Refrigeration and Heat Pump Technology. The aim of this department is to develop, implement and test: — systems for

  7. Domestic Refrigeration, Freezer, and Window Air Conditioner Service. Teacher Edition.

    Science.gov (United States)

    Clemons, Mark

    This curriculum guide contains six units of instruction for a course in domestic refrigerator, freezer, and window air conditioner service. The units cover the following topics: (1) service fundamentals; (2) mechanical components and functions; (3) electrical components and control devices; (4) refrigerator and freezer service; (5) domestic ice…

  8. Japanese Refrigerators : A Field Performance Analysis : Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Short, John A.

    1990-02-01

    The Pacific Northwest Electric Power Planning and Conservation Act, signed into law December 5, 1980, mandated regionwide energy conservation practices. Under the Act, BPA must identify and implement cost-effective electric energy options and programs for the Pacific Northwest. The Residential Technology Section in the Division of Resource Management supports current residential energy conservation programs and designs and conducts various research and development projects, of which this project is one. Laboratory test procedures used by the Japanese had shown their refrigerators to be about 50 percent more efficient than American-made refrigerators. A previous BPA study tested 12 Japanese refrigerators according to the USDOE laboratory procedure. When tested to the DOE procedure, Japanese refrigerators used about 43 percent more energy than when tested by the Japanese procedure. This study compared in-home energy use of 12 Japanese refrigerators identical to those in the laboratory test to both the Japanese and USDOE laboratory tests. 7 refs., 9 tabs.

  9. Application of magnetic refrigeration and its assessment - Annual report 2007

    Energy Technology Data Exchange (ETDEWEB)

    Kitanovski, A.; Vuarnoz, D.; Diebold, M.; Gonin, C.; Egolf, P. W.

    2007-07-01

    This annual report for the Swiss Federal Office of Energy (SFOE) takes a look at the work done in 2007 at the University of Applied Sciences of Western Switzerland on a project involving refrigeration based on magnetic effects. Possible refrigeration technologies and the evaluation of the potential of magnetic refrigeration are discussed. A calculation tool developed to determine the coefficient of performance (COP) values and the exergy efficiency as a function of magnetic field strength and rotational frequency for rotary types of magnetic refrigerators is introduced. Two applications that are considered to be very interesting for initial research, namely a household refrigerator without a freezing compartment and a large-size central chilling unit are discussed. The COP values of such large-scale systems are commented on. The study of the use of even superconducting magnets is considered as being an economic solution.

  10. Energy Savings Potential and RD&D Opportunities for Non-Vapor-Compression HVAC Technologies

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2014-03-01

    While vapor-compression technologies have served heating, ventilation, and air-conditioning (HVAC) needs very effectively, and have been the dominant HVAC technology for close to 100 years, the conventional refrigerants used in vapor-compression equipment contribute to global climate change when released to the atmosphere. This Building Technologies Office report: --Identifies alternatives to vapor-compression technology in residential and commercial HVAC applications --Characterizes these technologies based on their technical energy savings potential, development status, non-energy benefits, and other factors affecting end-user acceptance and their ability to compete with conventional vapor-compression systems --Makes specific research, development, and deployment (RD&D) recommendations to support further development of these technologies, should DOE choose to support non-vapor-compression technology further.

  11. EVALUATION OF OZONE-FRIENDLY HYDROFLUOROPROPANE-BASED ZEOTROPIC REFRIGERANT MIXTURES IN A LORENZ-MEUTZNER REFRIGERATOR/FREEZER

    Science.gov (United States)

    The two-evaporator (located in the freezer and fresh food compartments) design of the Lorenz-Meutzner (L-M) refrigerator/freezer (R/F) makes it a leading candidate for use of zeotropic refrigerant mixtures. Zeotrophic mixtures can have significant temperature glides during evapor...

  12. Miniaturized Air-to-Refrigerant Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Radermacher, Reinhard [Univ. of Maryland, College Park, MD (United States); Bacellar, Daniel [Univ. of Maryland, College Park, MD (United States); Aute, Vikrant [Univ. of Maryland, College Park, MD (United States); Huang, Zhiwei [Univ. of Maryland, College Park, MD (United States); Hwang, Yunho [Univ. of Maryland, College Park, MD (United States); Ling, Jiazhen [Univ. of Maryland, College Park, MD (United States); Muehlbauer, Jan [Univ. of Maryland, College Park, MD (United States); Tancabel, James [Univ. of Maryland, College Park, MD (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhang, Mingkan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-23

    Air-to-refrigerant Heat eXchangers (HX) are an essential component of Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R) systems, serving as the main heat transfer component. The major limiting factor to HX performance is the large airside thermal resistance. Recent literature aims at improving heat transfer performance by utilizing enhancement methods such as fins and small tube diameters; this has lead to almost exhaustive research on the microchannel HX (MCHX). The objective of this project is to develop a miniaturized air-to-refrigerant HX with at least 20% reduction in volume, material volume, and approach temperature compared to current state-of-the-art multiport flat tube designs and also be capable of production within five years. Moreover, the proposed HX’s are expected to have good water drainage and should succeed in both evaporator and condenser applications. The project leveraged Parallel-Parametrized Computational Fluid Dynamics (PPCFD) and Approximation-Assisted Optimization (AAO) techniques to perform multi-scale analysis and shape optimization with the intent of developing novel HX designs whose thermal-hydraulic performance exceeds that of state-of-the-art MCHX. Nine heat exchanger geometries were initially chosen for detailed analysis, selected from 35+ geometries which were identified in previous work at the University of Maryland, College Park. The newly developed optimization framework was exercised for three design optimization problems: (DP I) 1.0kW radiator, (DP II) 10kW radiator and (DP III) 10kW two-phase HX. DP I consisted of the design and optimization of 1.0kW air-to-water HX’s which exceeded the project requirements of 20% volume/material reduction and 20% better performance. Two prototypes for the 1.0kW HX were prototyped, tested and validated using newly-designed airside and refrigerant side test facilities. DP II, a scaled version DP I for 10kW air-to-water HX applications, also yielded optimized HX designs

  13. Properties and Cycle Performance of Refrigerant Blends Operating Near and Above the Refrigerant Critical Point, Task 1: Refrigerant Properties

    Energy Technology Data Exchange (ETDEWEB)

    Mark O. McLinden; Arno Laesecke; Eric W. Lemmon; Joseph W. Magee; Richard A. Perkins

    2002-08-30

    The main goal of this project was to investigate and compare the performance of an R410A air conditioner to that of an R22 air conditioner, with specific interest in performance at high ambient temperatures at which the condenser of the R410A system may be operating above the refrigerant's critical point. Part 1 of this project consisted of measuring thermodynamic properties R125, R410A and R507A, measuring viscosity and thermal conductivity of R410A and R507A and comparing data to mixture models in NIST REFPROP database. For R125, isochoric (constant volume) heat capacity was measured over a temperature range of 305 to 397 K (32 to 124 C) at pressures up to 20 MPa. For R410A, isochoric heat capacity was measured along 8 isochores with a temperature range of 303 to 397 K (30 to 124 C) at pressures up to 18 MPa. Pressure-density-temperature was also measured along 14 isochores over a temperature range of 200 to 400 K (-73 to 127 C) at pressures up to 35 MPa and thermal conductivity along 6 isotherms over a temperature range of 301 to 404 K (28 to 131 C) with pressures to 38 MPa. For R507A, viscosity was measured along 5 isotherms over a temperature range of 301 to 421 K (28 to 148 C) at pressures up to 83 MPa and thermal conductivity along 6 isotherms over a temperature range of 301 to 404 K (28 to 131 C) with pressures to 38 MPa. Mixture models were developed to calculate the thermodynamic properties of HFC refrigerant mixtures containing R32, R125, R134a and/or R125. The form of the model is the same for all the blends considered, but blend-specific mixing functions are required for the blends R32/125 (R410 blends) and R32/134a (a constituent binary of R407 blends). The systems R125/134a, R125/143a, R134a/143a, and R134a/152a share a common, generalized mixing function. The new equation of state for R125 is believed to be the most accurate and comprehensive formulation of the properties for that fluid. Likewise, the mixture model developed in this work is the

  14. Mixing of multiple metal vapours into an arc plasma in gas tungsten arc welding of stainless steel

    Science.gov (United States)

    Park, Hunkwan; Trautmann, Marcus; Tanaka, Keigo; Tanaka, Manabu; Murphy, Anthony B.

    2017-11-01

    A computational model of the mixing of multiple metal vapours, formed by vaporization of the surface of an alloy workpiece, into the thermal arc plasma in gas tungsten arc welding (GTAW) is presented. The model incorporates the combined diffusion coefficient method extended to allow treatment of three gases, and is applied to treat the transport of both chromium and iron vapour in the helium arc plasma. In contrast to previous models of GTAW, which predict that metal vapours are swept away to the edge of the arc by the plasma flow, it is found that the metal vapours penetrate strongly into the arc plasma, reaching the cathode region. The predicted results are consistent with published measurements of the intensity of atomic line radiation from the metal vapours. The concentration of chromium vapour is predicted to be higher than that of iron vapour due to its larger vaporization rate. An accumulation of chromium vapour is predicted to occur on the cathode at about 1.5 mm from the cathode tip, in agreement with published measurements. The arc temperature is predicted to be strongly reduced due to the strong radiative emission from the metal vapours. The driving forces causing the diffusion of metal vapours into the helium arc are examined, and it is found that diffusion due to the applied electric field (cataphoresis) is dominant. This is explained in terms of large ionization energies and the small mass of helium compared to those of the metal vapours.

  15. Metal-Nonmetal Transition and Homogeneous Nucleation of Mercury Vapour

    Science.gov (United States)

    Uchtmann, H.; Rademann, K.; Hensel, F.

    The paper presents ionization potentials of mercury clusters obtained by photoelectron spectroscopy which provide evidence that a size-dependent gradual transition from van der Waals-type to metallic interaction occurs in Hgx-clusters for × > 13. In order to probe the role of this nonmetal to metal transition in the homogeneous nucleation process of supersaturated mercury vapour we have determined the supersaturation necessary for homogeneous condensation of mercury vapour in the temperature range 250 to 320 K. The measurements were made using an upward thermal diffusion cloud chamber. The results demonstrate that none of the current theories for homogeneous nucleation satisfactorily predict the observed critical supersaturations. The measured values are about 3 orders of magnitude lower than the values predicted by the conventional Becker-Döring-Zeldovitch-theory.Translated AbstractMetall-Nichtmetallübergang und homogene Keimbildung bei QuecksilberdampfEs werden photoelektronenspektroskopische Messungen der Ionisationspotentiale von im Molekularstrahl synthetisierten Quecksilberclustern als Funktion der Größe beschrieben. Sie zeigen, daß ein größenabhängiger kontinuierlicher Übergang von van der Waals-Bindung zu metallischer Bindung für Cluster mit mehr als 13 Hg-Atomen auftritt. Um erste Informationen über den Einfluß dieses Übergangs von nichtmetallischem zu metallischem Verhalten auf den Keimbildungsprozeß in übersättigten Quecksilberdämpfen zu erhalten, werden zusätzlich Untersuchungen der homogenen Kondensation von übersättigten Quecksilberdämpfen im Temperaturbereich zwischen 250 bis 320 K mit einer Diffusionsnebelkammer berichtet. Die erhaltenen Ergebnisse können mit keiner der existierenden Theorien für die homogene Kondensation beschrieben werden. Die beobachteten Werte für die die homogene Kondensation auslösende kritische Übersättigung sind um drei Größenordnungen größer als die mit der klassischen Becker

  16. Influence of collisional rate coefficients on water vapour excitation

    Science.gov (United States)

    Daniel, F.; Goicoechea, J. R.; Cernicharo, J.; Dubernet, M.-L.; Faure, A.

    2012-11-01

    Context. Water is a key molecule in many astrophysical studies that deal with star or planet forming regions, evolved stars, and galaxies. Its high dipole moment makes this molecule subthermally populated under the typical conditions of most astrophysical objects. This motivated calculation of various sets of collisional rate coefficients (CRC) for H2O (with He or H2), which are needed to model its rotational excitation and line emission. Aims: The most accurate set of CRC are the quantum rates that involve H2. However, they have been published only recently, and less accurate CRC (quantum with He or quantum classical trajectory (QCT) with H2) were used in many studies before that. This work aims to underline the impact that the new available set of CRC have on interpretations of water vapour observations. Methods: We performed accurate non-local, non-LTE radiative transfer calculations using different sets of CRC to predict the line intensities from transitions that involve the lowest energy levels of H2O (E find that the intensities based on the quantum and QCT CRC are in good agreement. However, at relatively low H2 volume density (n(H2) find differences in the predicted line intensities of up to a factor of ~3 for the bulk of the lines. Most of the recent studies interpreting early Herschel Space Observatory spectra have used the QCT CRC. Our results show that, although the global conclusions from those studies will not be drastically changed, each case has to be considered individually, since depending on the physical conditions, the use of the QCT CRC may lead to a mis-estimate of the water vapour abundance of up to a factor of ~3. Additionally, the comparison of the quantum state-to-state and thermalised CRC, including the description of the population of the H2 rotational levels, show that above TK ~ 100 K, large differences are expected from those two sets for the p-H2 symmetry. Finally, we find that at low temperature (i.e. TK < 100 K) modelled line

  17. An Evaluation of the Environmental Impact of Different Commercial Supermarket Refrigeration Systems Using Low Global Warming Potential Refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Beshr, Mohamed [University of Maryland, College Park; Aute, Vikrant [University of Maryland, College Park; Abdelaziz, Omar [ORNL; Fricke, Brian A [ORNL; Radermacher, Reinhard [University of Maryland, College Park

    2014-01-01

    Commercial refrigeration systems consumed 1.21 Quads of primary energy in 2010 and are known to be a major source for refrigerant charge leakage into the environment. Thus, it is important to study the environmental impact of commercial supermarket refrigeration systems and improve their design to minimize any adverse impacts. The system s Life Cycle Climate Performance (LCCP) was presented as a comprehensive metric with the aim of calculating the equivalent mass of carbon dioxide released into the atmosphere throughout its lifetime, from construction to operation and destruction. In this paper, an open source tool for the evaluation of the LCCP of different air-conditioning and refrigeration systems is presented and used to compare the environmental impact of a typical multiplex direct expansion (DX) supermarket refrigeration systems based on three different refrigerants as follows: two hydrofluorocarbon (HFC) refrigerants (R-404A, and R-407F), and a low global warming potential (GWP) refrigerant (N-40). The comparison is performed in 8 US cities representing different climates. The hourly energy consumption of the refrigeration system, required for the calculation of the indirect emissions, is calculated using a widely used building energy modeling tool (EnergyPlus). A sensitivity analysis is performed to determine the impact of system charge and power plant emission factor on the LCCP results. Finally, we performed an uncertainty analysis to determine the uncertainty in total emissions for both R-404A and N-40 operated systems. We found that using low GWP refrigerants causes a considerable drop in the impact of uncertainty in the inputs related to direct emissions on the uncertainty of the total emissions of the system.

  18. Sensing response of copper phthalocyanine salt dispersed glass with organic vapours

    Energy Technology Data Exchange (ETDEWEB)

    Ridhi, R.; Sachdeva, Sheenam; Saini, G. S. S.; Tripathi, S. K., E-mail: surya@pu.ac.in [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (INDIA) Fax: +91-172-2783336; Tel.:+91-172-2544362 (India)

    2016-05-06

    Copper Phthalocyanine and other Metal Phthalocyanines are very flexible and tuned easily to modify their structural, spectroscopic, optical and electrical properties by either functionalizing them with various substituent groups or by replacing or adding a ligand to the central metal atom in the phthalocyanine ring and accordingly can be made sensitive and selective to various organic species or gaseous vapours. In the present work, we have dispersed Copper Phthalocyanine Salt (CuPcS) in sol-gel glass form using chemical route sol-gel method and studied its sensing mechanism with organic vapours like methanol and benzene and found that current increases onto their exposure with vapours. A variation in the activation energies was also observed with exposure of vapours.

  19. Pervaporation and vapour permeation of methanol and MTBE through a microporous methylated silica membrane

    NARCIS (Netherlands)

    de Bruijn, F.T.

    2006-01-01

    The combination of conventional unit operations with pervaporation or vapour permeation membrane separation processes offers opportunities for process intensification in terms of augmenting capacity and decreasing energy consumption of conventional unit operations. The MTBE production process is an

  20. Signal transduction pathway(s) in guard cells after prolonged exposure to low vapour pressure deficit

    NARCIS (Netherlands)

    Ali Niaei Fard, S.

    2014-01-01

    Keywords: Abscisic acid, Arabidopsis thaliana, calcium, CYP707As, desiccation, environmental factors, guard cells’ signalling pathway, hydrogen peroxide, natural variation, nitric oxide, photosystem II efficiency, RD29A, relative water content, secondary messengers, stomata, vapour pressure