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Sample records for simulated refrigerator panels

  1. Performance evaluation of solar photovoltaic panel driven refrigeration system

    Rajoria, C. S.; Singh, Dharmendra; Gupta, Pankaj Kumar

    2018-03-01

    The solar photovoltaic (PV) panel driven refrigeration system employs solar PV panel and play a vital role when combined with storage batteries. The variation in performance of solar PV panel driven refrigeration system has been experimentally investigated in this paper. The change in battery voltage is analyzed with respect to panel size. Different series and parallel combinations have been applied on four solar PV panels of 35W each to get 24V. With the above combination a current in the range of 3-5 ampere has been obtained depending upon the solar intensity. A refrigerator of 110 W and 50 liters is used in the present investigation which requires 0.80 ampere AC at 230 V. The required current and voltage has been obtained from an inverter which draws about 7 ampere DC from the battery bank at 24V. The compressor of the refrigerator consumed 110W which required a PV panel size of 176 W approximately. It is important to note that the compressor consumed about 300W for first 50 milliseconds, 130 W for next five seconds and gradually comes to 110 W in 65 seconds. Thus panel size should be such that it may compensate for the initial load requirement.

  2. Refrigeration Cycle Design for Refrigerant Mixtures by Molecular Simulation

    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 simulation s * vapor–liquid equilibrium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.853, year: 2010

  3. Simulation of the Energy Saver refrigeration system

    Barton, H.R. Jr.; Nicholls, J.E.; Mulholland, G.T.

    1981-10-01

    The helium refrigeration for the Energy Saver is supplied by a Central Helium Liquefier and 24 Satellite Refrigerators installed over a 1-1/4 square mile area. An interactive, software simulator has been developed to calculate the refrigeration available from the cryogenic system over a wide range of operating conditions. The refrigeration system simulator incorporates models of the components which have been developed to quantitatively describe changes in system performance. The simulator output is presented in a real-time display which has been used to search for the optimal operating conditions of the Satellite-Central system, to examine the effect of an extended range of operating parameters and to identify equipment modifications which would improve the system performance

  4. Systematic modelling and simulation of refrigeration systems

    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 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....

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

    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

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

    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

  7. Dynamic Simulation of AN Helium Refrigerator

    Deschildre, C.; Barraud, A.; Bonnay, P.; Briend, P.; Girard, A.; Poncet, J. M.; Roussel, P.; Sequeira, S. E.

    2008-03-01

    A dynamic simulation of a large scale existing refrigerator has been performed using the software Aspen Hysys®. The model comprises the typical equipments of a cryogenic system: heat exchangers, expanders, helium phase separators and cold compressors. It represents the 400 W @ 1.8 K Test Facility located at CEA—Grenoble. This paper describes the model development and shows the possibilities and limitations of the dynamic module of Aspen Hysys®. Then, comparison between simulation results and experimental data are presented; the simulation of cooldown process was also performed.

  8. Simulation of absorption refrigeration system for automobile application

    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.

  9. Modular Modelling and Simulation Approach - Applied to Refrigeration Systems

    Sørensen, Kresten Kjær; Stoustrup, Jakob

    2008-01-01

    This paper presents an approach to modelling and simulation of the thermal dynamics of a refrigeration system, specifically a reefer container. A modular approach is used and the objective is to increase the speed and flexibility of the developed simulation environment. The refrigeration system...

  10. Numerical simulation of pulse-tube refrigerators

    Lyulina, I.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2004-01-01

    A new numerical model has been introduced to study steady oscillatory heat and mass transfer in the tube section of a pulse-tube refrigerator. Conservation equations describing compressible gas flow in the tube are solved numerically, using high resolution schemes. The equation of conservation of

  11. Thermodynamic simulation of ammonia-water absorption refrigeration system

    Sathyabhama A.

    2008-01-01

    Full Text Available The ammonia-water absorption refrigeration system is attracting increasing research interests, since the system can be powered by waste thermal energy, thus reducing demand on electricity supply. The development of this technology demands reliable and effective system simulations. In this work, a thermodynamic simulation of the cycle is carried out to investigate the effects of different operating variables on the performance of the cycle. A computer program in C language is written for the performance analysis of the cycle.

  12. Study on the CFD simulation of refrigerated container

    Arif Budiyanto, Muhammad; Shinoda, Takeshi; Nasruddin

    2017-10-01

    The objective this study is to performed Computational Fluid Dynamic (CFD) simulation of refrigerated container in the container port. Refrigerated container is a thermal cargo container constructed from an insulation wall to carry kind of perishable goods. CFD simulation was carried out use cross sectional of container walls to predict surface temperatures of refrigerated container and to estimate its cooling load. The simulation model is based on the solution of the partial differential equations governing the fluid flow and heat transfer processes. The physical model of heat-transfer processes considered in this simulation are consist of solar radiation from the sun, heat conduction on the container walls, heat convection on the container surfaces and thermal radiation among the solid surfaces. The validation of simulation model was assessed uses surface temperatures at center points on each container walls obtained from the measurement experimentation in the previous study. The results shows the surface temperatures of simulation model has good agreement with the measurement data on all container walls.

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

    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.

  14. Review of numerical simulation of capillary tube using refrigerant mixtures

    Garcia-Valladares, O. [Centro de Investigacion en Energia de la UNAM, Morelos (Mexico)

    2004-05-01

    A detailed one-dimensional steady and transient state numerical simulation of the thermal and fluid-dynamic behaviour of capillary tube expansion devices considering metastable region and working with pure and mixed refrigerants has been developed and presented in previous works [Appl. Therm. Eng. 22 (2002) 173; Appl. Therm. Eng. 22 (2002) 379]. The discretized governing equations are coupled using an implicit step-by-step method. Due to the changes observed in the thermo-physical properties of mixtures using REFPROP v7.0 [Reference Fluid Thermodynamic and Transport Properties, NIST Standard Reference Database 23, Gaithersburg, MD 20899, USA, 2002] compared to REFPROP v5.0 [NIST Thermodynamic Properties of Refrigerants and Refrigerant Mixtures Database, Standard Reference Data Program, Gaithersburg, MD 20899, USA (February 1996)]; an extensive comparison of the numerical simulation developed with experimental data presented in the technical literature will be shown in order to demonstrate the accuracy of this detailed model. Finally, refrigerant-specific rating charts to predict in an easy way R-407C flow rates through adiabatic capillary tube are shown and used. (author)

  15. Review of numerical simulation of capillary tube using refrigerant mixtures

    Garcia-Valladares, O.

    2004-01-01

    A detailed one-dimensional steady and transient state numerical simulation of the thermal and fluid-dynamic behaviour of capillary tube expansion devices considering metastable region and working with pure and mixed refrigerants has been developed and presented in previous works [Appl. Therm. Eng. 22 (2002) 173; Appl. Therm. Eng. 22 (2002) 379]. The discretized governing equations are coupled using an implicit step-by-step method. Due to the changes observed in the thermo-physical properties of mixtures using REFPROP v7.0 [Reference Fluid Thermodynamic and Transport Properties, NIST Standard Reference Database 23, Gaithersbug, MD 20899, USA, 2002] compared to REFPROP v5.0 [NIST Thermodynamic Properties of Refrigerants and Refrigerant Mixtures Database, Standard Reference Data Program, Gaithersbug, MD 20899, USA (February 1996)]; an extensive comparison of the numerical simulation developed with experimental data presented in the technical literature will be shown in order to demonstrate the accuracy of this detailed model. Finally, refrigerant-specific rating charts to predict in an easy way R-407C flow rates through adiabatic capillary tube are shown and used

  16. Simulation of shell-and-tube condensers of the refrigerating machines with superheated and subcooled refrigerant

    Ciconkov, Risto

    1994-01-01

    Opposite to many authors who found the simulation of the shell-and-tube condensers on the condensing process only, in this work all thermodynamic processes which appear such as: the process of cooling the superheated refrigerant to the saturated vapor, the process of condensation and option with subcooling are considered. A selection of heat transfer equations is made corresponding to the processes, a mathematical model and adequate computer programme are composed. The functioning of this programme is presented on a concrete example. A computer programing knowledge for the using programme is not necessary. Neither is a programme support. (author)

  17. Dynamic simulation of variable capacity refrigeration systems under abnormal conditions

    Liang Nan; Shao Shuangquan; Tian Changqing; Yan Yuying

    2010-01-01

    There are often abnormal working conditions at evaporator outlet of a refrigeration system, such as two-phase state in transient process, and it is essential to investigate such transient behaviours for system design and control strategy. In this paper, a dynamic lumped parameter model is developed to simulate the transient behaviours of refrigeration system with variable capacity in both normal and abnormal working conditions. The appropriate discriminant method is adopted to switch the normal and abnormal conditions smoothly and to eliminate the simulated data oscillation. In order to verify the dynamic model, we built a test system with variable frequency compressor, water-cooling condenser, evaporator and electronic expansion valve. Calculated values from the mathematical model show reasonable agreement with the experimental data. The simulation results show that the transient behaviours of the variable capacity refrigeration system in the abnormal working conditions can be calculated reliably with the dynamic model when the compressor rotary speed or the opening of electronic expansion valve changes abruptly.

  18. Experimental and numerical study of heat transfer across insulation wall of a refrigerated integral panel van

    Glouannec, Patrick; Michel, Benoit; Delamarre, Guillaume; Grohens, Yves

    2014-01-01

    This paper presents an experimental and numerical design study of an insulation wall for refrigerated vans. The thermophysical properties of the insulating multilayer panel, the external environment impact (solar irradiation, temperature, etc.) and durability are taken into account. Different tools are used to characterize the thermal performances of the insulation walls and the thermal properties of the insulation materials are measured. In addition, an experiment at the wall scale is carried out and a 2D FEM model of heat and mass transfer within the wall is formulated. Three configurations are studied with this design approach. Multilayer insulation walls containing reflective multi-foil insulation, aerogel and phase change materials (PCM) are tested. Promising results are obtained with these materials, especially the reduction of peak heat transfer and energy consumption during the daytime period. Furthermore, the major influence of solar irradiation is highlighted as it can increase the peak heat transfer crossing the insulation wall by up to 43%. Nevertheless, we showed that the use of reflective multi-foil insulation and aerogel layers allowed decreasing this impact by 27%. - Highlights: • A design study of an insulation wall for a refrigerated van is carried out. • Experimental and numerical studies of multilayer insulation walls are performed. • The major influence of solar irradiation is highlighted. • New insulation materials (reflective multi-foil, aerogel and PCM) are tested

  19. The panel-free simulator

    Lucas, G.

    1990-01-01

    This paper reports on a simulator which is a device which simulates a physical object for training purposes. Although effective tools, Simulators posses two primary limitations. First, due to the dynamic nature of the simulated object, the Simulator may require frequent modification to remain an accurate representation. When Simulators are upgraded, modifications often turn out to be expensive. Increasingly, Simulator upgrades are required by regulations, no matter how costly. The second limitation is the number of personnel that can utilize a Simulator simultaneously. Engineers, Instructors, and Students are frequently forced work second and third shifts to obtain Simulator time. A study of existing Simulators by the Power Plant Simulation Division of Link-Miles Corporation spawned a software development project. The purpose of this project was to minimize the limitations of existing Simulators by designing a system to enhance Simulator modifications and usage

  20. Conception and simulation of an improved solar refrigeration unit

    Chaouachi, B.; Gabsi, S.

    2006-01-01

    If the solar energy possesses the advantage to be c lean , free and new able, this last is probably, considered like an adapted potential solution, that answers in even time at a economic preoccupation and ecological problems. Among the main done currently research is the use of free source to make operate system of refrigeration. following a bibliographic study on the absorption cycles, the utilized couples absorbents-refrigerating fluids and the capture of the solar energy, an unit refrigeration using an improved solar absorption cycle of ammonia has been conceived and studied. The simulation results in permanent regime concerned the determination of the variation of the performance criteria mainly according to the operatives kept for this study. The obtained results showed, that the improved mono pressure absorption cycle of ammonia is suitable well for the cold production by means of the solar energy and that with a simple plate collector we can reach a power, of the order of 900 watts sufficient for domestic use.(Author)

  1. RECENT PROGRESS IN DYNAMIC PROCESS SIMULATION OF CRYOGENIC REFRIGERATORS

    Kuendig, A.

    2008-01-01

    At the CEC 2005 a paper with the title ''Helium refrigerator design for pulsed heat load in Tokamaks'' was presented. That paper highlighted the control requirements for cryogenic refrigerators to cope with the expected load variations of future nuclear fusion reactors. First dynamic computer simulations have been presented.In the mean time, the computer program is enhanced and a new series of process simulations are available. The new program considers not only the heat flows and the temperature variations within the heat exchangers, but also the variation of mass flows and pressure drops. The heat transfer numbers now are calculated in dependence of the flow speed and the gas properties. PI-controllers calculate the necessary position of specific valves for maintaining pressures, temperatures and the rotation speed of turbines.Still unsatisfactory is the fact, that changes in the process arrangement usually are attended by adjustments in the program code. It is the main objective of the next step of development a more flexible code which enables that any user defined process arrangements can be assembled by input data

  2. Computational tool for simulation of power and refrigeration cycles

    Córdoba Tuta, E.; Reyes Orozco, M.

    2016-07-01

    Small improvement in thermal efficiency of power cycles brings huge cost savings in the production of electricity, for that reason have a tool for simulation of power cycles allows modeling the optimal changes for a best performance. There is also a big boom in research Organic Rankine Cycle (ORC), which aims to get electricity at low power through cogeneration, in which the working fluid is usually a refrigerant. A tool to design the elements of an ORC cycle and the selection of the working fluid would be helpful, because sources of heat from cogeneration are very different and in each case would be a custom design. In this work the development of a multiplatform software for the simulation of power cycles and refrigeration, which was implemented in the C ++ language and includes a graphical interface which was developed using multiplatform environment Qt and runs on operating systems Windows and Linux. The tool allows the design of custom power cycles, selection the type of fluid (thermodynamic properties are calculated through CoolProp library), calculate the plant efficiency, identify the fractions of flow in each branch and finally generates a report very educational in pdf format via the LaTeX tool.

  3. Simulation of Transcritical CO2 Refrigeration System with Booster Hot Gas Bypass in Tropical Climate

    Santosa, I. D. M. C.; Sudirman; Waisnawa, IGNS; Sunu, PW; Temaja, IW

    2018-01-01

    A Simulation computer becomes significant important for performance analysis since there is high cost and time allocation to build an experimental rig, especially for CO2 refrigeration system. Besides, to modify the rig also need additional cos and time. One of computer program simulation that is very eligible to refrigeration system is Engineering Equation System (EES). In term of CO2 refrigeration system, environmental issues becomes priority on the refrigeration system development since the Carbon dioxide (CO2) is natural and clean refrigerant. This study aims is to analysis the EES simulation effectiveness to perform CO2 transcritical refrigeration system with booster hot gas bypass in high outdoor temperature. The research was carried out by theoretical study and numerical analysis of the refrigeration system using the EES program. Data input and simulation validation were obtained from experimental and secondary data. The result showed that the coefficient of performance (COP) decreased gradually with the outdoor temperature variation increasing. The results show the program can calculate the performance of the refrigeration system with quick running time and accurate. So, it will be significant important for the preliminary reference to improve the CO2 refrigeration system design for the hot climate temperature.

  4. Control panel handling of a nuclear simulator

    Martin Polo, F.; Jimenez Fraustro, L.A.; Banuelos Galindo, A.; Diamant Rubinstein, A.

    1985-01-01

    The handling of the control panels for a Nuclear Simulator for operating training is described. The control panels are handled by a set of intelligent controllers, each with at least two processors (8035 - Communications Controller and a 8085 - Master processor). The Controllers are connected to the main computers (Two dual processor Gould concept 32/6780 and a single processor Gould concept 32/6705) via serial asynchronous channels in a multidrop, star-like architecture. The controllers transmit to the main computers only the changes detected and receive the whole set of output variables as computed by the mathematical models of the Nuclear Plant

  5. Carnot type magnetic refrigeration below 4.2 K - computer simulation

    Hashimoto, T.; Numazawa, T.; Maro, T.

    1984-01-01

    Cooling devices based on a utilization of the Carnot type magnetic refrigeration cycle are usually selected for the temperature range from 20 K to 1.8 K. However, the refrigeration power in the case of such devices is frequently limited by the heat transfer coefficient between the heat source and the magnetic working substance. Thus, in a magnetic refrigerator studied by Delpuech et al. (1981), the refrigeration power is mainly restricted by the heat transfer coefficient in the isothermal magnetization process at 4.2 K. The present investigation is concerned with the development of a method for achieving high refrigeration power on the basis of a study utilizing computer simulation. One of two methods considered for enhancing refrigeration power is related to the change in the magnetic field, while the other method involves an enlargement of the effective area of gadolinium-gallium-garnet (GGG) with the aid of deep grooves in the surface. 6 references

  6. One-dimensional numerical simulation of the Stirling-type pulse-tube refrigerator

    Etaati, M.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2007-01-01

    Change of title: One-dimensional numerical simulation of the Stirling-type pulse-tube cooler. Pulse-tube refrigeration (PTR) is a new technology for cooling down to extremely low temperatures. In this paper a particular type, the so-called Stirling single-stage refrigerator, is considered. A

  7. THERMODYNAMIC ANALYSIS AND SIMULATION OF A NEW COMBINED POWER AND REFRIGERATION CYCLE USING ARTIFICIAL NEURAL NETWORK

    Hossein Rezvantalab

    2011-01-01

    Full Text Available In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

  8. Computer simulation with TRNSYS for a mobile refrigeration system incorporating a phase change thermal storage unit

    Liu, Ming; Saman, Wasim; Bruno, Frank

    2014-01-01

    Highlights: • A mobile refrigeration system incorporating phase change thermal storage was simulated using TRNSYS. • A TRNSYS component of a phase change thermal storage unit was created and linked to other components from TRNSYS library. • The temperature in the refrigerated space can be predicted using this TRNSYS model under various conditions. • A mobile refrigeration system incorporating PCM and an off-peak electric driven refrigeration unit is feasible. • The phase change material with the lowest melting temperature should be selected. - Abstract: This paper presents a new TRNSYS model of a refrigeration system incorporating phase change material (PCM) for mobile transport. The PCTSU is charged by an off-vehicle refrigeration unit and the PCM provides cooling when discharging and the cooling released is utilized to cool down the refrigerated space. The advantage of this refrigeration system compared to a conventional system is that it consumes less energy and produces significantly lower greenhouse gas emissions. A refrigeration system for a typical refrigerated van is modelled and simulations are performed with climatic data from four different locations. The main components of the TRNSYS model are Type 88 (cooling load estimation) and Type 300 (new PCTSU component), accompanied by other additional components. The results show that in order to maintain the temperature of the products at −18 °C for 10 h, a total of 250 kg and 390 kg of PCM are required for no door opening and 20 door openings during the transportation, respectively. In addition, a parametric study is carried out to evaluate the effects of location, size of the refrigerated space, number of door openings and melting temperature of the PCM on the thermal performance

  9. Modeling and simulation of photovoltaic solar panel

    Belarbi, M.; Haddouche, K.; Midoun, A.

    2006-01-01

    In this article, we present a new approach for estimating the model parameters of a photovoltaic solar panel according to the irradiance and temperature. The parameters of the one diode model are given from the knowledge of three operating points: short-circuit, open circuit, and maximum power. In the first step, the adopted approach concerns the resolution of the system of equations constituting the three operating points to write all the model parameters according to series resistance. Secondly, we make an iterative resolution at the optimal operating point by using the Newton-Raphson method to calculate the series resistance value as well as the model parameters. Once the panel model is identified, we consider other equations for taking into account the irradiance and temperature effect. The simulation results show the convergence speed of the model parameters and the possibility of visualizing the electrical behaviour of the panel according to the irradiance and temperature. Let us note that a sensitivity of the algorithm at the optimal operating point was observed owing to the fact that a small variation of the optimal voltage value leads to a very great variation of the identified parameters values. With the identified model, we can develop algorithms of maximum power point tracking, and make simulations of a solar water pumping system.(Author)

  10. A Simulation Modeling Approach Method Focused on the Refrigerated Warehouses Using Design of Experiment

    Cho, G. S.

    2017-09-01

    For performance optimization of Refrigerated Warehouses, design parameters are selected based on the physical parameters such as number of equipment and aisles, speeds of forklift for ease of modification. This paper provides a comprehensive framework approach for the system design of Refrigerated Warehouses. We propose a modeling approach which aims at the simulation optimization so as to meet required design specifications using the Design of Experiment (DOE) and analyze a simulation model using integrated aspect-oriented modeling approach (i-AOMA). As a result, this suggested method can evaluate the performance of a variety of Refrigerated Warehouses operations.

  11. Simulation Of Aqua-Ammonia Refrigeration System Using The Cape-Open To Cape-Open COCO Simulator

    Janavi Gohil

    2017-03-01

    Full Text Available In this paper we have simulated a flow sheet of aqua ammonia refrigeration system using Cape Open simulator. The main aim of writing this paper is to compare the results obtained from thermodynamic simulation of aqua ammonia refrigeration system and the results obtained from the flow sheet simulation in Cape-Open to Cape-Open COCO simulator. The corresponding COP values obtained from both the sources are calculated and compared. With the error being very minute the calculations using simulator prove to be more efficient and timesaving when compared to the results obtained by calculations done using tedious thermodynamic simulations and constant mass balance for different process conditions.

  12. Using a Linux Cluster for Parallel Simulations of an Active Magnetic Regenerator Refrigerator

    Petersen, T.F.; Pryds, N.; Smith, A.

    2006-01-01

    This paper describes the implementation of a Comsol Multiphysics model on a Linux computer Cluster. The Magnetic Refrigerator (MR) is a special type of refrigerator with potential to reduce the energy consumption of household refrigeration by a factor of two or more. To conduct numerical analysis....... The coupled set of equations and the transient convergence towards the final steady state means that the model has an excessive solution time. To make parametric studies practical, the developed model was implemented on a Cluster to allow parallel simulations, which has decreased the solution time...

  13. Simulation methods of rocket fuel refrigerating with liquid nitrogen and intermediate heat carrier

    O. E. Denisov

    2014-01-01

    Full Text Available Temperature preparation of liquid propellant components (LPC before fueling the tanks of rocket and space technology is the one of the operations performed by ground technological complexes on cosmodromes. Refrigeration of high-boiling LPC is needed to increase its density and to create cold reserve for compensation of heat flows existing during fueling and prelaunch operations of space rockets.The method and results of simulation of LPC refrigeration in the recuperative heat exchangers with heat carrier which is refrigerated by-turn with liquid nitrogen sparging. The refrigerating system consists of two tanks (for the chilled coolant and LPC, LPC and heat carrier circulation loops with heat exchanger and system of heat carrier refrigeration in its tank with bubbler. Application of intermediate heat carrier between LPC and liquid nitrogen allows to avoid LPC crystallization on cold surfaces of the heat exchanger.Simulation of such systems performance is necessary to determine its basic design and functional parameters ensuring effective refrigerating of liquid propellant components, time and the amount of liquid nitrogen spent on refrigeration operation. Creating a simulator is quite complicated because of the need to take into consideration many different heat exchange processes occurring in the system. Also, to determine the influence of various parameters on occurring processes it is necessary to take into consideration the dependence of all heat exchange parameters on each other: heat emission coefficients, heat transfer coefficients, heat flow amounts, etc.The paper offers an overview of 10 references to foreign and Russian publications on separate issues and processes occurring in liquids refrigerating, including LPC refrigeration with liquid nitrogen. Concluded the need to define the LPC refrigerating conditions to minimize cost of liquid nitrogen. The experimental data presented in these publications is conformed with the application of

  14. CoolPack – Simulation tools for refrigeration systems

    Jakobsen, Arne; Rasmussen, Bjarne D.; Andersen, Simon Engedal

    1999-01-01

    CoolPack is a collection of programs used for energy analysis and optimisation of refrigeration systems. CoolPack is developed at the Department of Energy Engineering at the Technical University of Denmark. The Danish Energy Agency finances the project. CoolPack is freeware and can be downloaded...

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

    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...... regenerators with complex flow arrange-ments, providing high performance at lower pressure drop, are investigated. Correspondingly a one dimensional model is pre-sented and comparative studies between novel and conventional regenerators are carried out by simulation. The effect of regen-erator geometries...

  16. Simulation on a proposed large-scale liquid hydrogen plant using a multi-component refrigerant refrigeration system

    Krasae-in, Songwut [Norwegian University of Science and Technology, Kolbjorn Hejes vei 1d, NO-7491 Trondheim (Norway); Stang, Jacob H.; Neksa, Petter [SINTEF Energy Research AS, Kolbjorn Hejes vei 1d, NO-7465 Trondheim (Norway)

    2010-11-15

    A proposed liquid hydrogen plant using a multi-component refrigerant (MR) refrigeration system is explained in this paper. A cycle that is capable of producing 100 tons of liquid hydrogen per day is simulated. The MR system can be used to cool feed normal hydrogen gas from 25 C to the equilibrium temperature of -193 C with a high efficiency. In addition, for the transition from the equilibrium temperature of the hydrogen gas from -193 C to -253 C, the new proposed four H{sub 2} Joule-Brayton cascade refrigeration system is recommended. The overall power consumption of the proposed plant is 5.35 kWh/kg{sub LH2}, with an ideal minimum of 2.89 kWh/kg{sub LH2}. The current plant in Ingolstadt is used as a reference, which has an energy consumption of 13.58 kWh/kg{sub LH2} and an efficiency of 21.28%: the efficiency of the proposed system is 54.02% or more, where this depends on the assumed efficiency values for the compressors and expanders. Moreover, the proposed system has some smaller-size heat exchangers, much smaller compressor motors, and smaller crankcase compressors. Thus, it could represent a plant with the lowest construction cost with respect to the amount of liquid hydrogen produced in comparison to today's plants, e.g., in Ingolstadt and Leuna. Therefore, the proposed system has many improvements that serve as an example for future hydrogen liquefaction plants. (author)

  17. CFD-simulations of a 4π-contiuous-mode dilution refrigerator for the CB-ELSA experiment

    Altfelde, Timo; Bornstein, Marcel; Dutz, Hartmut; Goertz, Stefan; Miebach, Roland; Reeve, Scott; Runkel, Stefan; Sommer, Marco; Streit, Benjamin [Physikalisches Institut, Bonn (Germany)

    2015-07-01

    The polarized target group at Bonn operates a dilution refrigerator for double polarization experiments at the Crystal Barrel in Bonn. To get high target polarizations and long relaxation times low temperatures are indispensable. To reach temperatures below 30 mK and to allow for the use of an internal polarization magnet, the polarized target group is building a new continuous mode dilution refrigerator. As a optimizing tool for the construction of dilution refrigerators and for a better understanding of the different incoming and outgoing fluid streams several CFD-simulations are done. First the different streams are simulated independently for different parts of the refrigerator to get a better estimation of the flow parameters. Then the simulation is extended to include the heat exchange between the different streams at the heat exchangers for different operational parameters of the refrigerator. Afterwards the precooling stages of the refrigerator will be tested to compare the predicted and the measured operational parameters.

  18. CFD-simulations of a 4π-continuous-mode dilution refrigerator for the CB-ELSA experiment

    Bornstein, Marcel; Dutz, Hartmut; Goertz, Stefan; Reeve, Scott; Runkel, Stefan [Physikalisches Institut, Bonn Univ. (Germany); Collaboration: CBELSA/TAPS-Collaboration

    2016-07-01

    The polarized target group at Bonn operates a dilution refrigerator for double polarization experiments at the Crystal Barrel in Bonn. To get high target polarizations and long relaxation times low temperatures are indispensable. To reach temperatures below 30 mK and to allow for the use of an internal polarization magnet, the polarized target group is building a new continuous mode dilution refrigerator. As a optimizing tool for the construction of dilution refrigerators and for a better understanding of the different incoming and outgoing fluid streams several Computational Fluid Dynamic simulations are done. The heat exchange between the different streams of the refrigerator were simulated for the precooling stages within one simulation including a submesh for each fluid and solid. This leads to a better estimation of the flow characteristics and the operational parameter of the refrigerator. The last steps of construction and the preparation of the refrigerator for first test measurements are ongoing.

  19. CFD simulations and reduced order modeling of a refrigerator compartment including radiation effects

    Bayer, Ozgur; Oskay, Ruknettin; Paksoy, Akin; Aradag, Selin

    2013-01-01

    Highlights: ► Free convection in a refrigerator is simulated including radiation effects. ► Heat rates are affected drastically when radiation effects are considered. ► 95% of the flow energy can be represented by using one spatial POD mode. - Abstract: Considering the engineering problem of natural convection in domestic refrigerator applications, this study aims to simulate the fluid flow and temperature distribution in a single commercial refrigerator compartment by using the experimentally determined temperature values as the specified constant wall temperature boundary conditions. The free convection in refrigerator applications is evaluated as a three-dimensional (3D), turbulent, transient and coupled non-linear flow problem. Radiation heat transfer mode is also included in the analysis. According to the results, taking radiation effects into consideration does not change the temperature distribution inside the refrigerator significantly; however the heat rates are affected drastically. The flow inside the compartment is further analyzed with a reduced order modeling method called Proper Orthogonal Decomposition (POD) and the energy contents of several spatial and temporal modes that exist in the flow are examined. The results show that approximately 95% of all the flow energy can be represented by only using one spatial mode

  20. Steady-state thermodynamic simulation and structural design of the dephlegmator used in mixed-refrigerant Joule-Thomson refrigerators

    Li, Mei; Gong, Maoqiong; Guo, Hao; Sun, Zhaohu; Wu, Jianfeng

    2016-01-01

    Highlights: • Good agreements and the feasibility of the MESH model were found. • Fine applicability and low energy consumption of the dephlegmator were addressed. • A clear and comprehensive three-dimensional dephlegmator model was shown. - Abstract: Dephlegmators can be used to reduce the energy consumption and simplify the layout of the mixed-refrigerant Joule–Thomson (MRJT) cycle. Heat-exchange characteristics and refrigeration design are currently based on highly simplified assumptions. Synthesis methods to efficiently solve all design issues of dephlegmators in MRJT cycle are insufficient. No suitable separation module is available for the simultaneous heat and mass transfer processes in Aspen Plus because the module should be programmed and incorporated into Aspen Plus as a user-defined unit. In this paper, a systematic steady-state method was proposed for the detailed design of dephlegmators for gas mixture separation, considering the simulation and heat exchanger design simultaneously. The material balance, vapor–liquid equilibrium, mole fraction summation and heat balance (MESH) model was programmed in FORTRAN language. Good agreements and the feasibility of the MESH model were found. Deviations between the simulation results and patent data were all within 5%. The errors in the predicted temperatures of vapor and liquid products were less than 2% and 10%, respectively. Fine applicability and low energy consumption of the dephlegmator were addressed. The mole fraction of n-butane in the liquid phase had high recovery ratio of 90%. The dephlegmator decreased more than 30% of energy consumption compared with the traditional distillation tower under similar separation effects. In the structural design process, the dephlegmator was divided into certain segments by baffle plates on the basis of segmented calculation. The heat transfer coefficient, heat transfer area, pressure drop, and structural parameters of the dephlegmator were evaluated. A clear

  1. Front panel engineering with CAD simulation tool

    Delacour, Jacques; Ungar, Serge; Mathieu, Gilles; Hasna, Guenther; Martinez, Pascal; Roche, Jean-Christophe

    1999-04-01

    THe progress made recently in display technology covers many fields of application. The specification of radiance, colorimetry and lighting efficiency creates some new challenges for designers. Photometric design is limited by the capability of correctly predicting the result of a lighting system, to save on the costs and time taken to build multiple prototypes or bread board benches. The second step of the research carried out by company OPTIS is to propose an optimization method to be applied to the lighting system, developed in the software SPEOS. The main features of the tool requires include the CAD interface, to enable fast and efficient transfer between mechanical and light design software, the source modeling, the light transfer model and an optimization tool. The CAD interface is mainly a prototype of transfer, which is not the subjects here. Photometric simulation is efficiently achieved by using the measured source encoding and a simulation by the Monte Carlo method. Today, the advantages and the limitations of the Monte Carlo method are well known. The noise reduction requires a long calculation time, which increases with the complexity of the display panel. A successful optimization is difficult to achieve, due to the long calculation time required for each optimization pass including a Monte Carlo simulation. The problem was initially defined as an engineering method of study. The experience shows that good understanding and mastering of the phenomenon of light transfer is limited by the complexity of non sequential propagation. The engineer must call for the help of a simulation and optimization tool. The main point needed to be able to perform an efficient optimization is a quick method for simulating light transfer. Much work has been done in this area and some interesting results can be observed. It must be said that the Monte Carlo method wastes time calculating some results and information which are not required for the needs of the simulation

  2. Simulation of the SSC refrigeration system using the ASPEN/SP process simulator

    Rasson, J.; Dweck, J.

    1990-01-01

    The SSC Magnet must be maintained at a superconducting temperature of 4 K. The proposed refrigeration cooling processes consist of fairly simple closed cycles which take advantage of the Joule-Thompson effect via a series of expansions and compressions of helium gas which has been precooled by liquid nitrogen. The processes currently under consideration consist of three cycles, the 20 K shield cooling, the 4.0 K helium refrigerator and the helium liquefier. The process units which are to be employed are compressors, turbines, expanders, mixers, flashes, two stream heat exchangers and multiple stream heat exchangers. The cycles are to be operated at or near steady state. Due to the large number of competing cooling sector designs to be considered and the high capital and operating costs of the proposed processes, the SSC Laboratory requires a software tool for the validation and optimization of the individual designs and for the performance of cost-benefit analyses among competing designs. Since these processes are steady state flow processes involving primarily standard unit operations, a decision was made to investigate the application of a commercial process simulator to the task. Several months of internal evaluations by the SSC Laboratory revealed that while the overall structure and calculation approach of a number of the commercial simulators were appropriate for this task, all were lacking essential capabilities in the areas of thermodynamic property calculations for cryogenic systems and modeling of complex, multiple stream heat exchangers. An acceptable thermodynamic model was provided and a series of simple, but three software vendors. Based on the results of the benchmark tests, the ASPEN/SP process simulator was selected for future modeling work. 2 refs., 4 figs

  3. Simulation of the SSC [Superconducting Super Collider] refrigeration system using the ASPEN/SP process simulator

    Rasson, J.; Dweck, J.

    1990-08-01

    The SSC Magnet must maintain at a super conducting temperature of 4 K. The proposed refrigeration cooling processes consist of fairly simple closed cycles which take advantage of the Joule-Thompson effect via a series of expansions and compressions of helium gas which has been precooled by liquid nitrogen. The processes currently under consideration consist of three cycles, the 20 K shield cooling, the 45 K helium refrigerator and the helium liquefier. The process units which are to be employed are compressors, turbines, expanders, mixers, flashes, two stream heat exchangers and multiple stream heat exchangers. The cycles are to be operated at or near steady state. Due to the large number of competing cooling sector designs to be considered and the high capital and operating costs of the proposed processes, the SSC Laboratory requires a software tool for the validation and optimization of the individual designs and for the performance of cost-benefit analyses among competing designs. Since these processes are steady state flow processes involving primarily standard unit operations, a decision was made to investigate the application of a commercial process simulator to the task. Several months of internal evaluations by the SSC Laboratory revealed that while the overall structure and calculation approach of number of the commercial simulators were appropriate for this task, all were lacking essential capabilities in the areas of thermodynamic property calculations for cryogenic systems and modeling of complex, multiple stream heat exchangers. An acceptable thermodynamics model was provided and a series of simple, but representative benchmark problems developed. The model and problems were provided to three software vendors. Based on the results of the benchmark test, the ASPEN/SP process simulator was selected for future modeling work

  4. Absorption Refrigeration Cycles with Ammonia-Ionic Liquid Working Pairs Studied by Molecular Simulation.

    Becker, Tim M; Wang, Meng; Kabra, Abhishek; Jamali, Seyed Hossein; Ramdin, Mahinder; Dubbeldam, David; Infante Ferreira, Carlos A; Vlugt, Thijs J H

    2018-04-18

    For absorption refrigeration, it has been shown that ionic liquids have the potential to replace conventional working pairs. Due to the huge number of possibilities, conducting lab experiments to find the optimal ionic liquid is infeasible. Here, we provide a proof-of-principle study of an alternative computational approach. The required thermodynamic properties, i.e., solubility, heat capacity, and heat of absorption, are determined via molecular simulations. These properties are used in a model of the absorption refrigeration cycle to estimate the circulation ratio and the coefficient of performance. We selected two ionic liquids as absorbents: [emim][Tf 2 N], and [emim][SCN]. As refrigerant NH 3 was chosen due to its favorable operating range. The results are compared to the traditional approach in which parameters of a thermodynamic model are fitted to reproduce experimental data. The work shows that simulations can be used to predict the required thermodynamic properties to estimate the performance of absorption refrigeration cycles. However, high-quality force fields are required to accurately predict the cycle performance.

  5. Absorption Refrigeration Cycles with Ammonia–Ionic Liquid Working Pairs Studied by Molecular Simulation

    2018-01-01

    For absorption refrigeration, it has been shown that ionic liquids have the potential to replace conventional working pairs. Due to the huge number of possibilities, conducting lab experiments to find the optimal ionic liquid is infeasible. Here, we provide a proof-of-principle study of an alternative computational approach. The required thermodynamic properties, i.e., solubility, heat capacity, and heat of absorption, are determined via molecular simulations. These properties are used in a model of the absorption refrigeration cycle to estimate the circulation ratio and the coefficient of performance. We selected two ionic liquids as absorbents: [emim][Tf2N], and [emim][SCN]. As refrigerant NH3 was chosen due to its favorable operating range. The results are compared to the traditional approach in which parameters of a thermodynamic model are fitted to reproduce experimental data. The work shows that simulations can be used to predict the required thermodynamic properties to estimate the performance of absorption refrigeration cycles. However, high-quality force fields are required to accurately predict the cycle performance. PMID:29749996

  6. Dynamic simulation of a 1.8K refrigeration unit for the LHC

    Bradu, B; Niculescu, S I

    2009-01-01

    A new simulation toolkit has been successfully developed at the European Organization for Nuclear Research (CERN) and applied to existing cryogenic installations as, for example, the 1.3kW @ 4.5K cold-box of the Compact Muon Solenoid (CMS) experiment and the central CERN helium liquefier. The simulator is based on different interconnected simulation tools and provides simulations of cryogenic systems with their control and supervision. In this paper, we present an application to a complete 2.4kW @ 1.8K refrigeration unit for the LHC. It includes the cryogenic centrifugal compressors coupled to the warm compression station.

  7. CFD simulation and experimental validation of a GM type double inlet pulse tube refrigerator

    Banjare, Y. P.; Sahoo, R. K.; Sarangi, S. K.

    2010-04-01

    Pulse tube refrigerator has the advantages of long life and low vibration over the conventional cryocoolers, such as GM and stirling coolers because of the absence of moving parts in low temperature. This paper performs a three-dimensional computational fluid dynamic (CFD) simulation of a GM type double inlet pulse tube refrigerator (DIPTR) vertically aligned, operating under a variety of thermal boundary conditions. A commercial computational fluid dynamics (CFD) software package, Fluent 6.1 is used to model the oscillating flow inside a pulse tube refrigerator. The simulation represents fully coupled systems operating in steady-periodic mode. The externally imposed boundary conditions are sinusoidal pressure inlet by user defined function at one end of the tube and constant temperature or heat flux boundaries at the external walls of the cold-end heat exchangers. The experimental method to evaluate the optimum parameters of DIPTR is difficult. On the other hand, developing a computer code for CFD analysis is equally complex. The objectives of the present investigations are to ascertain the suitability of CFD based commercial package, Fluent for study of energy and fluid flow in DIPTR and to validate the CFD simulation results with available experimental data. The general results, such as the cool down behaviours of the system, phase relation between mass flow rate and pressure at cold end, the temperature profile along the wall of the cooler and refrigeration load are presented for different boundary conditions of the system. The results confirm that CFD based Fluent simulations are capable of elucidating complex periodic processes in DIPTR. The results also show that there is an excellent agreement between CFD simulation results and experimental results.

  8. Evaluation of Variable Refrigerant Flow Systems Performance on Oak Ridge National Laboratory s Flexible Research Platform: Part 3 Simulation Analysis

    Im, Piljae [ORNL; Cho, Heejin [Mississippi State University (MSU); Kim, Dongsu [Mississippi State University (MSU); Cox, Sam [Mississippi State University (MSU)

    2016-08-01

    This report provides second-year project simulation results for the multi-year project titled “Evaluation of Variable Refrigeration Flow (VRF) system on Oak Ridge National Laboratory (ORNL)’s Flexible Research Platform (FRP).”

  9. Analytical Modelling and Simulation of Photovoltaic Panels and Arrays

    H. Bourdoucen

    2007-12-01

    Full Text Available In this paper, an analytical model for PV panels and arrays based on extracted physical parameters of solar cells is developed. The proposed model has the advantage of simplifying mathematical modelling for different configurations of cells and panels without losing efficiency of PV system operation. The effects of external parameters, mainly temperature and solar irradiance have been considered in the modelling. Due to their critical effects on the operation of the panel, effects of series and shunt resistances were also studied. The developed analytical model has been easily implemented, simulated and validated using both Spice and Matlab packages for different series and parallel configurations of cells and panels. The results obtained with these two programs are in total agreement, which make the proposed model very useful for researchers and designers for quick and accurate sizing of PV panels and arrays.

  10. Simulation and experimental validation of the performance of a absorption refrigerator

    Olbricht, Michael; Luke, Andrea

    2015-01-01

    The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [de

  11. WIPP panel simulations with gas generation

    DeVries, K.L.; Callahan, G.D.; Munson, D.E.

    1996-01-01

    An important issue in nuclear waste repository performance is the potential for fracture development resulting in pathways for release of radionuclides beyond the confines of the repository. A series of demonstration calculations using structural finite element analyses are presented here to examine the effect of internal gas generation on the response of a sealed repository. From the calculated stress fields, the most probable location for a fracture to develop was determined to be within the pillars interior to the repository for the range of parameter values considered. If a fracture interconnects the rooms and panels of the repository, fracture opening produces significant additional void volume to limit the excess gas pressure to less than 1.0 MPa above the overburden pressure. Consequently, the potential for additional fracture development into the barrier pillar is greatly reduced, which provides further confidence that the waste will be contained within the repository

  12. Simulator for design absorption refrigeration system; Simulador para projeto de ciclos de refrigeracao por absorcao

    Morejon, C.F.M.; Brum, N. de C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Mecanica]. E-mails: Camilo_freddy@hotmail.com; Nisio@serv.com.ufrj.br

    2000-07-01

    This work presents a development of a thermal fluid dynamics model and a solution of a steady state absorption refrigeration cycle, with ammonia water as the working fluid. Analytical thermodynamics models expressing the enthalpy in function of pressure, temperature and composition (h=f(P,T,x)), are used with the aim to design all of the cycle devices, moved by any type of energy such as solar, natural gas, steam or electrical energy (Morejon and Hackenberg, 1978). The development of the analysis is carried out by the application of thermal fluid dynamics concepts together with a detailed study of the heat and mass transfer in the different cycle stages. The thermodynamic cycle model, obtained from equation of state for ammonia - water mixtures (Ziegker and Trepp, 1984), is represented by the relation h - x (enthalpy-composition) for different pressures and temperatures. The obtained models are used to implement computational codes in MAPLE-V facilitating the design and simulation of refrigeration system. This study can be applied in the systems of air conditioning and refrigeration chambers design. (author)

  13. Mathematical models for photovoltaic solar panel simulation

    Santos, Jose Airton A. dos; Gnoatto, Estor; Fischborn, Marcos; Kavanagh, Edward [Universidade Tecnologica Federal do Parana (UTFPR), Medianeira, PR (Brazil)], Emails: airton@utfpr.edu.br, gnoatto@utfpr.edu.br, fisch@utfpr.edu.br, kavanagh@utfpr.edu.br

    2008-07-01

    A photovoltaic generator is subject to several variations of solar intensity, ambient temperature or load, that change your point of operation. This way, your behavior should be analyzed by such alterations, to optimize your operation. The present work sought to simulate a photovoltaic generator, of polycrystalline silicon, by characteristics supplied by the manufacturer, and to compare the results of two mathematical models with obtained values of field, in the city of Cascavel, for a period of one year. (author)

  14. Simulated hail impact testing of photovoltaic solar panels

    Moore, D.; Wilson, A.; Ross, R.

    1978-01-01

    Techniques used to simulate and study the effect of hail on photovoltaic solar panels are described. Simulated hail stones (frozen ice spheres projected at terminal velocity) or steel balls were applied by air guns, gravity drop, or static loading. Tests with simulated hail and steel balls yielded different results. The impact strength of 10 commercially available flat-plate photovoltaic modules was tested. It was found that none of the six panel designs incorporating clear potting silicone material as the outermost layer remained undamaged by 1-in. simulated hailstones, while a photovoltaic module equipped with a 0.188-in.-thick acrylic cover sheet would be able to withstand the impact of a 2-in.-diameter hailstone.

  15. Software Simulates Sight: Flat Panel Mura Detection

    2008-01-01

    In the increasingly sophisticated world of high-definition flat screen monitors and television screens, image clarity and the elimination of distortion are paramount concerns. As the devices that reproduce images become more and more sophisticated, so do the technologies that verify their accuracy. By simulating the manner in which a human eye perceives and interprets a visual stimulus, NASA scientists have found ways to automatically and accurately test new monitors and displays. The Spatial Standard Observer (SSO) software metric, developed by Dr. Andrew B. Watson at Ames Research Center, measures visibility and defects in screens, displays, and interfaces. In the design of such a software tool, a central challenge is determining which aspects of visual function to include while accuracy and generality are important, relative simplicity of the software module is also a key virtue. Based on data collected in ModelFest, a large cooperative multi-lab project hosted by the Optical Society of America, the SSO simulates a simplified model of human spatial vision, operating on a pair of images that are viewed at a specific viewing distance with pixels having a known relation to luminance. The SSO measures the visibility of foveal spatial patterns, or the discriminability of two patterns, by incorporating only a few essential components of vision. These components include local contrast transformation, a contrast sensitivity function, local masking, and local pooling. By this construction, the SSO provides output in units of "just noticeable differences" (JND) a unit of measure based on the assumed smallest difference of sensory input detectable by a human being. Herein is the truly amazing ability of the SSO, while conventional methods can manipulate images, the SSO models human perception. This set of equations actually defines a mathematical way of working with an image that accurately reflects the way in which the human eye and mind behold a stimulus. The SSO is

  16. Simulation of Stamping Process of Automotive Panel Considering Die Deformation

    Keum, Y.T.; Ahn, I.H.; Lee, I.K.; Song, M.H.; Kwon, S.O.; Park, J.S.

    2005-01-01

    In order to see the effect of die deformation on the forming of sheet metals, the draw-ins, strains, and spring-backs of an automotive fender panels are numerically simulated considering the die deformation, which is found by the simultaneous structural analysis of press and dies. By coupling the forming analysis and the structural analysis, the die deformation is simultaneously taken into account in the forming process. Furthermore, for the consideration of load difference transferred among the upper die, punch, and blank holder due to the changes in sheet thickness, the gap elements are employed instead of the blank sheet in the structural analysis. The numerical simulation results of an automotive fender draw panel are compared with the measurements. The comparison of the forming and spring-back analysis results between the rigid die and the deformed die shows that the deformed tool provides more accurate forming and spring-back prediction

  17. Thermal Simulation of the Fresh Food Compartment in a Domestic Refrigerator

    Juan M. Belman-Flores

    2017-01-01

    Full Text Available In the field of domestic refrigeration, it is important to look for methods that can be used to simulate, and, thus, improve the thermal behavior of the fresh food compartment. In this sense, this study proposes some methods to model the thermal behavior of this compartment when the shelves’ positions are changed. Temperature measurements at specific locations in this compartment were obtained. Several shelf position combinations were performed to use three 2D interpolation methods in order to simulate the temperature mean and the temperature variance. The methods used were: Lagrange’s interpolation, cubic spline interpolation and bilinear interpolation. Two validation points were chosen to verify the proposed methods. By comparing the experimental results with the computer simulations, it was possible to conclude that the method of Lagrange’s interpolation provided values that were not close to the real measured values. On the other hand, it was observed that the method of bilinear interpolation offered the best results, estimating values which were very close to the actual experimental measurements. These interpolation methods were used to build color thermal graphs that can be used to find some of the most appropriate shelf position combinations in this type of refrigerator. By inspection of these thermal graphs, it can be seen that the lowest average temperature was obtained when one shelf was located at 24.5 cm while the second shelf was located at 29.5 cm measured from the top of the compartment. In the same way, it can be seen that the minimum temperature variance was obtained when only one shelf was inside the compartment and this shelf was located at 29.5 cm.

  18. Prediction of Isoenthalps, Joule–Thomson Coefficients and Joule–Thomson Inversion Curves of Refrigerants by Molecular Simulation

    Figueroa-Gerstenmaier, S.; Lísal, Martin; Nezbeda, Ivo; Smith, W.R.; Trejos, V.M.

    2014-01-01

    Roč. 375, AUG 15 (2014), s. 143-151 ISSN 0378-3812 Grant - others:NSERCC(CA) OGP-1041 Institutional support: RVO:67985858 Keywords : refrigerants * molecular simulation * Joule-Thomson Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.200, year: 2014

  19. Simulation and experimental validation of the performance of a absorption refrigerator; Simulation und experimentelle Validierung des Betriebsverhaltens einer Absorptionskaeltemaschine

    Olbricht, Michael; Luke, Andrea [Kassel Univ. (Germany). Fachgebiet Technische Thermodynamik

    2015-07-01

    The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [German] Die beiden groessten Hemmnisse fuer eine staerkere Marktdurchdringung von Absorptionskaeltemaschinen (AKM) sind deren hohe Anschaffungskosten sowie die Baugroesse der Apparate, die durch die ungenauen Methoden zur Anlagenauslegung begruendet sind. Als Beitrag fuer eine verbesserte Auslegung wird ein thermodynamisches Modell zur Beschreibung des Betriebsverhaltens einer AKM mit dem Arbeitsstoffpaar Wasser/Lithiumbromid vorgestellt. In diesem werden die Prozesse in den Einzelapparaten abgebildet und im systemischen

  20. SIMULATION OF NON-AZEOTROPIC REFRIGERANT MIXTURES FOR USE IN A DUAL-CIRCUIT REFRIGERATOR/FREEZER WITH COUNTERCURRENT HEAT EXCHANGES

    The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. This RF is housed in a stan...

  1. PIV measurement of the flow field in a domestic refrigerator model: Comparison with 3D simulations

    Ben Amara, S.; Laguerre, O.; Flick, D. [UMR Genie Industriel Alimentaire (Cemagref-AgroParisTech-INRA) - Cemagref, Parc de Tourvoie, BP 44, 92185 Antony Cedex (France); Charrier-Mojtabi, M.-C.; Lartigue, B. [Universite Paul Sabatier, Laboratoire PHASE, E.A. 3208, 118 route de Narbonne, 31062 Toulouse Cedex 4 (France)

    2008-12-15

    PIV (particle image velocimetry) measurements of flow field due to natural convection in a parallelepipedic enclosure representing a domestic refrigerator model (scale 1) have been undertaken in order to determine the thickness of the hydrodynamic boundary layers and to study the flow motions depending on the boundary conditions applied on the vertical walls. One of the vertical walls is maintained at a negative and constant temperature either on the totality or on one part of its surface: this wall acts as the evaporator. The other walls are in contact with external air at constant temperature. The velocity measurements have been made in the symmetry plane of the enclosure. Unsteady recirculations have been observed at the bottom of the cavity. The influence of both the temperature and the dimension of the cold wall has been studied. Numerical simulations using CFD software (Fluent) have been then performed. In the numerical model, we assumed that the temperature of the evaporator is constant while an uniform global heat transfer coefficient has been used to describe the heat exchange with the external air at constant temperature. We considered laminar 3D flows and took into account the heat transfer by radiation between the different walls of the cavity. The results obtained with the 3D numerical simulations are in quite good agreement with the experimental airflow measurements using the PIV technique. (author)

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

    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.

  3. Numerical simulation of wind loads on solar panels

    Su, Kao-Chun; Chung, Kung-Ming; Hsu, Shu-Tsung

    2018-05-01

    Solar panels mounted on the roof of a building or ground are often vulnerable to strong wind loads. This study aims to investigate wind loads on solar panels using computational fluid dynamic (CFD). The results show good agreement with wind tunnel data, e.g. the streamwise distribution of mean surface pressure coefficient of a solar panel. Wind uplift for solar panels with four aspect ratios is evaluated. The effect of inclined angle and clearance (or height) of a solar panel is addressed. It is found that wind uplift of a solar panel increases when there is an increase in inclined angle and the clearance above ground shows an opposite effect.

  4. Simulation and Optimization of an Innovative Dual Mixed Component Refrigerant Cycle (DMRC) for Natural Gas Offshore Liquefaction Plants

    SHAHBA, L.A.; Fahmy, M.F.M.

    2004-01-01

    Simulation and optimization of an innovative liquefaction process used for the LNG production , namely the Dual Mixed Refrigerant Process (DMRC) has been conducted using the HYSYS simulator .This new process is especially suitable for off shore natural gas liquefaction plants. A numerical optimization technique has been used to determine the optimum conditions for Egyptian natural gas feed source. The investigation of the effect of different compositions of the Mixed refrigerants used was conducted. Meanwhile, the investigation of the influence of the temperature of cooling water used was conducted. The best optimum conditions for the DMRC process were determined .The optimum results achieved for the DMRC process revealed that the DMRC process can be successfully applied as a promising technique for off shore natural gas liquefaction plants

  5. Study of change of refrigerant R22 in chiller units by simulation in EcosimPro

    Prieto, J.; Molina, C.; Olmedo, J.; Gavilan, C. J.

    2014-01-01

    On January 1, 2010 is forbidden to hold any stock of virgin R 2 2 refrigerant and it is also forbidden to use virgin R 2 2 refrigerant for the service and maintenance of equipment under the new European Community Regulation 20137/2000. On January 1, 2015 and stock of R 2 2, even if reclaimed or recycled, will be illegal to hold. In accordance with the European Community regulation, Cofrentes Nuclear Power Plant begins the R 2 2 retrofit. (Author)

  6. Optimization of Ventilation and Alarm Setting During the Process of Ammonia Leak in Refrigeration Machinery Room Based on Numerical Simulation

    Dongliang Liu

    2017-03-01

    Full Text Available In order to optimize the ventilation effect of ammonia leakage in the refrigeration machinery room, a food processing enterprise is selected as the subject investigated. The velocity and concentration field distribution during the process of ammonia leakage are discussed through simulation of refrigeration machinery room using CFD software. The ventilation system of the room is optimized in three aspects which are named air distribution, ventilation volume and discharge outlet. The influence of the ammonia alarm system through ventilation is also analyzed. The results show that it will be better to set the discharge outlet at the top of the plant than at the side of the wall, and the smaller of the distance between the air outlet and the ammonia gathering area, the better of the effect of ventilation will be. The air flow can be improved and the vortex flow can be reduced if the ventilation volume, the number of air vents and the exhaust velocity are reasonably arranged. Not only the function of the alarm could be ensured, but also the scope of the detection area could be enlarged if the detectors are set on the ceiling of the refrigeration units or the ammonia storage vessel.

  7. Numerical simulation of a three-stage Stirling-type pulse-tube refrigerator

    Etaati, M.A.

    2011-01-01

    The pulse-tube refrigerator (PTR) is a rather new device for cooling down to extremely low temperatures, i.e. below 4 K. The PTR works by the cyclic compression and expansion of helium that flows through a regenerator made of porous material, a cold heat exchanger, a tube, a hot heat exchanger and

  8. One-dimensional simulation of a stirling three-stage pulse-tube refrigerator

    Etaati, M.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2009-01-01

    A one-dimensional mathematical model is derived for a three-stage pulse-tube refrigerator (PTR) that is based on the conservation laws and the ideal gas law. The three-stage PTR is regarded as three separate single-stage PTRs that are coupled via proper junction conditions. At the junctions there

  9. One-dimensional simulation of a Stirling three-stage pulse-tube refrigerator

    Etaati, M.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2009-01-01

    A one-dimensional mathematical model is derived for a three-stage pulse-tube refrigerator (PTR) that is based on the conservation laws and the ideal gas law. The three-stage PTR is regarded as three separate single-stage PTRs that are coupled via proper junction conditions. At the junctions there

  10. Absorption Refrigeration Cycles with Ammonia-Ionic Liquid Working Pairs Studied by Molecular Simulation

    Becker, T.M.; Wang, M.; Kabra, Abhishek; Jamali, S.H.; Ramdin, M.; Dubbeldam, D.; Infante Ferreira, C.A.; Vlugt, T.J.H.

    2018-01-01

    For absorption refrigeration, it has been shown that ionic liquids have the potential to replace conventional working pairs. Due to the huge number of possibilities, conducting lab experiments to find the optimal ionic liquid is infeasible. Here, we provide a proof-of-principle study of an

  11. Simulated and experimental performance of split packaged air conditioner using refrigerant HC-290 as a substitute for HCFC-22

    Padalkar, Atul S.; Mali, Kundlik V.; Devotta, Sukumar

    2014-01-01

    This paper discusses the use of propane (HC-290) as a safe and energy efficient alternative to HCFC-22 in a typical split air conditioner with nominal cooling capacities up to 5.1 kW. Initially split air conditioner performance is simulated for cooling capacity, energy efficiency ratio (EER), and refrigerant charge. Tests were conducted for different test cases in a psychrometric test chamber with HCFC-22 and HC-290. The test conditions considered are as per Indian Standards, IS 1391 (1992) Part I. The various parameters considered were based on simulated performance with the objective to achieve maximum EER for the desired cooling capacity. As the flammability is an issue for HC-290, the reduction of HC-290 charge was another objective. Two different types of condensers, first with smaller size tubing and another parallel flow condenser (PFC) or minichannel condenser were used in order to reduce HC-290 charge. For HC-290, the highest EER achieved was 3.7 for cooling capacity 4.90 kW for a refrigerant charge of 360 g. The important safety aspects of using HC-290 in air conditioner are discussed. The refrigerant charge as per EN 378 for different cooling capacities and room sizes is also considered. -- Highlights: • Simulation for performance of split air conditioner has been done using HC-290 as a replacement to HCFC-22. • The safety aspects of HC-290 are discussed when used in split air conditioner. • HC-290 was tested in psychrometric test chamber as per IS 1391 part 1. • With PFC, HC-290 gave highest EER of 3.7 which was 37% higher than that of HCFC-22. • The lowest HC-290 charge used in test was 340 g which is well below LFL

  12. Simulated performance of biomass gasification based combined power and refrigeration plant for community scale application

    Chattopadhyay, S., E-mail: suman.mech09@gmail.com [Department of Mechanical Engineering, NIT, Agarpara, Kolkata – 700109, West Bengal (India); Mondal, P., E-mail: mondal.pradip87@gmail.com; Ghosh, S., E-mail: sudipghosh.becollege@gmail.com [Department of Mechanical Engineering, IIEST, Shibpur, Howrah – 711103, West Bengal (India)

    2016-07-12

    Thermal performance analysis and sizing of a biomass gasification based combined power and refrigeration plant (CPR) is reported in this study. The plant is capable of producing 100 kWe of electrical output while simultaneously producing a refrigeration effect, varying from 28-68 ton of refrigeration (TR). The topping gas turbine cycle is an indirectly heated all-air cycle. A combustor heat exchanger duplex (CHX) unit burns producer gas and transfer heat to air. This arrangement avoids complex gas cleaning requirements for the biomass-derived producer gas. The exhaust air of the topping GT is utilized to run a bottoming ammonia absorption refrigeration (AAR) cycle via a heat recovery steam generator (HRSG), steam produced in the HRSG supplying heat to the generator of the refrigeration cycle. Effects of major operating parameters like topping cycle pressure ratio (r{sub p}) and turbine inlet temperature (TIT) on the energetic performance of the plant are studied. Energetic performance of the plant is evaluated via energy efficiency, required biomass consumption and fuel energy savings ratio (FESR). The FESR calculation method is significant for indicating the savings in fuel of a combined power and process heat plant instead of separate plants for power and process heat. The study reveals that, topping cycle attains maximum power efficiency of 30%in pressure ratio range of 8-10. Up to a certain value of pressure ratio the required air flow rate through the GT unit decreases with increase in pressure ratio and then increases with further increase in pressure ratio. The capacity of refrigeration of the AAR unit initially decreases up to a certain value of topping GT cycle pressure ratio and then increases with further increase in pressure ratio. The FESR is found to be maximized at a pressure ratio of 9 (when TIT=1100°C), the maximum value being 53%. The FESR is higher for higher TIT. The heat exchanger sizing is also influenced by the topping cycle pressure ratio

  13. Evaluation of ionic liquids as absorbents for ammonia absorption refrigeration cycles using COSMO-based process simulations

    Ruiz, E.; Ferro, V.R., E-mail: victor.ferro@uam.es; Riva, J. de; Moreno, D.; Palomar, J.

    2014-06-01

    Highlights: • NH{sub 3}–IL absorption cycles are modeled by COSMO-based Aspen simulations. • Proposed a priori computational approach is validated using experimental data. • Cycle performance was analyzed for conventional and task-specific ILs. • IL solvents with high NH{sub 3} absorption capacity improve the cycle performance. • Using IL mixtures is revealed as promising alternative in NH{sub 3} absorption applications. - Abstract: COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia + ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant + absorbent) solutions. This behavior is strongly modulated by the ammonia

  14. Evaluation of ionic liquids as absorbents for ammonia absorption refrigeration cycles using COSMO-based process simulations

    Ruiz, E.; Ferro, V.R.; Riva, J. de; Moreno, D.; Palomar, J.

    2014-01-01

    Highlights: • NH 3 –IL absorption cycles are modeled by COSMO-based Aspen simulations. • Proposed a priori computational approach is validated using experimental data. • Cycle performance was analyzed for conventional and task-specific ILs. • IL solvents with high NH 3 absorption capacity improve the cycle performance. • Using IL mixtures is revealed as promising alternative in NH 3 absorption applications. - Abstract: COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia + ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant + absorbent) solutions. This behavior is strongly modulated by the ammonia absorption

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

    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...

  16. A mobility based vibroacoustic energy transmission simulation into an enclosure through a double-wall panel.

    Sahu, Atanu; Bhattacharya, Partha; Niyogi, Arup Guha; Rose, Michael

    2017-06-01

    Double-wall panels are known for their superior sound insulation properties over single wall panels as a sound barrier. The sound transmission phenomenon through a double-wall structure is a complex process involving vibroacoustic interaction between structural panels, the air-cushion in between, and the secondary acoustic domain. It is in this context a versatile and a fully coupled technique based on the finite-element-boundary element model is developed that enables estimation of sound transfer through a double-wall panel into an adjacent enclosure while satisfying the displacement compatibility across the interface. The contribution of individual components in the transmitted energy is identified through numerical simulations.

  17. Solar panel thermal cycling testing by solar simulation and infrared radiation methods

    Nuss, H. E.

    1980-01-01

    For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.

  18. Finite element simulation of a novel composite light-weight microporous cladding panel

    Tian, Lida; Wang, Dongyan

    2018-04-01

    A novel composite light-weight microporous cladding panel with matched connection detailing is developed. Numerical simulation on the experiment is conducted by ABAQUS. The accuracy and rationality of the finite element model is verified by comparison between the simulation and the experiment results. It is also indicated that the novel composite cladding panel is of desirable bearing capacity, stiffness and deformability under out-of-plane load.

  19. Fast Multilevel Panel Method for Wind Turbine Rotor Flow Simulations

    van Garrel, Arne; Venner, Cornelis H.; Hoeijmakers, Hendrik Willem Marie

    2017-01-01

    A fast multilevel integral transform method has been developed that enables the rapid analysis of unsteady inviscid flows around wind turbines rotors. A low order panel method is used and the new multi-level multi-integration cluster (MLMIC) method reduces the computational complexity for

  20. Numerical simulation of a three-stage stirling-type pulse-tube refrigerator

    Etaati, M.A.

    2011-06-22

    The pulse-tube refrigerator (PTR) is a rather new device for cooling down to extremely low temperatures, i.e. below 4 K. The PTR works by the cyclic compression and expansion of helium that flows through a regenerator made of porous material, a cold heat exchanger, a tube, a hot heat exchanger and an orifice, in series. In a Stirling-type PTR compression and expansion are generated by a piston. The compression increases the temperature of the helium in the tube and makes it flow towards the orifice; the expansion decreases the temperature and makes the helium flow backwards to the regenerator. The net effect of warmer helium flowing in one direction and colder helium in the opposite direction is that of cooling power at the cold heat exchanger. Three PTRs are inter-connected aiming to obtain the desired 4 K lowest temperature. The conservation laws of mass, momentum and energy, and an equation of state, are simplified using asymptotic analysis based on low Mach-numbers. The regenerator is modelled one-dimensionally with Darcy's law for flow resistance. The tube is modelled either one-dimensionally without resistance or two-dimensionally with axisymmetric laminar viscous flow. The heat transfer in the porous medium of the regenerator and in the solid tube wall is taken into account. The gas can be either ideal or real. All the material properties, including viscosity and conductivity, are taken temperature and pressure dependent. Three single-stage PTRs are connected with the regenerators in series and the tubes in parallel and six flow possibilities at the junctions are considered. Three by-passes (double-inlets) are used to enhance and tune the performance. The governing equations are numerically solved with a finite-difference method of nominally second-order accuracy in space and time. Pressure correction, flux limiter, 1D-2D connections and domain decomposition are the keywords here. Special attention is paid to suitable initial conditions, high resolution

  1. Thermoacoustic refrigeration

    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.

  2. Computer simulation of transitional process to the final stable Brayton cycle in magnetic refrigeration

    Numasawa, T.; Hashimoto, T.

    1981-01-01

    The final working cycle in the magnetic refrigeration largely depends on the heat transfer coefficient β in the system, the parameter γ of the heat inflow from the outer system to this cycle and the period tau of the cycle. Therefore, so as to make clear this dependence, the time variation of the Brayton cycle with β, γ and tau has been investigated. In the present paper the transitional process of this cycle and the dependence of the final cooling temperature of the heat load on β, γ and tau have all been shown. (orig.)

  3. Solar Powered Refrigeration System

    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.

  4. A full scope nuclear power plant simulator for multiple reactor types with virtual control panels

    Yonezawa, Hisanori; Ueda, Hiroki; Kato, Takahisa

    2017-01-01

    This paper summarizes a full scope nuclear power plant simulator for multiple reactor types with virtual control panels which Toshiba developed and delivered. After the Fukushima DAIICHI nuclear power plants accident, it is required that all the people who are engaged in the design, manufacturing, operation, maintenance, management and regulation for the nuclear power plant should learn the wide and deep knowledge about the nuclear power plant design including the severe accident. For this purpose, the training with a full scope simulator is one of the most suitable ways. However the existing full scope simulators which are consist of the control panels replica of the referenced plants are costly and they are hard to remodel to fit to the real plant of the latest condition. That's why Toshiba developed and delivered the new concept simulator system which covers multiple referenced plants even though they have different design like BWR and PWR. The control panels of the simulator are made by combining 69 large Liquid Crystal Display (LCD) panels with touch screen instead of a control panel replica of referenced plant. The screen size of the each panel is 42 inches and 3 displays are arranged in tandem for one unit and 23 units are connected together. Each panel displays switches, indicators, recorders and lamps with the Computer Graphics (CG) and trainees operate them with touch operations. The simulator includes a BWR and a PWR simulator model, which enable trainees to learn the wide and deep knowledge about the nuclear power plant of BWR and PWR reactor types. (author)

  5. Comparison of diverse climatic sources for the simulation of facilities of solar refrigeration; Comparacion de diversas fuentes climaticas para la simulacion de instalaciones de refrigeracion solar

    Bujedo, L. A.; Vicente, J.; Torre, C. de; Macia, A.; Rodriguez, J.

    2008-07-01

    With the present work they are sought to analyze the results based on simulations hourly of an installation of solar refrigeration by absorption, subjected to different sources of weather data. For it, the authors have modelled one of the facilities of the Technology Centre CARTIF located in Boecillo (Valladolid), under the environment TRNSYS. (Author)

  6. Solar concentrator panel and gore testing in the JPL 25-foot space simulator

    Dennison, E. W.; Argoud, M. J.

    1981-01-01

    The optical imaging characteristics of parabolic solar concentrator panels (or gores) have been measured using the optical beam of the JPL 25-foot space simulator. The simulator optical beam has been characterized, and the virtual source position and size have been determined. These data were used to define the optical test geometry. The point source image size and focal length have been determined for several panels. A flux distribution of a typical solar concentrator has been estimated from these data. Aperture photographs of the panels were used to determine the magnitude and characteristics of the reflecting surface errors. This measurement technique has proven to be highly successful at determining the optical characteristics of solar concentrator panels.

  7. Simulation Study of Discharging PCM Ceiling Panels through Night - time Radiative Cooling

    Bourdakis, Eleftherios; Kazanci, Ongun Berk; Grossule, F.

    2016-01-01

    demand. In the present simulation study, the coupling of nighttime radiative cooling with PCM for cooling an office room was investigated. For cooling water through nighttime radiative cooling two types of solar panels were utilized, an unglazed solar collector and photovoltaic/thermal (PV/T) panels...... provided by the PV/T panels was 43 W/m2 for Copenhagen, while for Milan and Athens it was 36 W/m2 and 34 W/m2, respectively. The cooling power of the unglazed solar collector was negligible. Finally, the total electricity produced in Copenhagen for the simulated period was 371 kWh, while for Milan...... and increase use of renewable energy sources. The aim is that by 2020 all new buildings should be nearly zero-energy buildings. A solution that could contribute to this is the combination of photovoltaic panels for the production of electricity and phase change material (PCM) for the reduction of peak cooling...

  8. Flammable refrigerants

    Gerwen, R.J.M. van; Verwoerd, M.; Oostendorp, P.A.

    1999-01-01

    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

  9. Accurate simulation of MPPT methods performance when applied to commercial photovoltaic panels.

    Cubas, Javier; Pindado, Santiago; Sanz-Andrés, Ángel

    2015-01-01

    A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions.

  10. Accurate Simulation of MPPT Methods Performance When Applied to Commercial Photovoltaic Panels

    Javier Cubas

    2015-01-01

    Full Text Available A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers’ datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions.

  11. Panel: The Future of Research in Modeling & Simulation

    2014-12-01

    Fomel and Claerbout 2009; Stodden 2010). It refers to the ability to recreate simulation results from existing simulation code and data...379(1): 317-333. 2809 Yilmaz, Taylor, Fujimoto, and Darema Stodden , V. 2010. “The Scientific Method in Practice: Reproducibility in the

  12. Multilevel panel method for wind turbine rotor flow simulations

    van Garrel, Arne

    2016-01-01

    Simulation methods of wind turbine aerodynamics currently in use mainly fall into two categories: the first is the group of traditional low-fidelity engineering models and the second is the group of computationally expensive CFD methods based on the Navier-Stokes equations. For an engineering

  13. Safety panel and new procedures evaluation by simulator tests

    Meslin, T.

    1986-01-01

    With more than thirty weeks of simulator testing (for the last three years only) and approximately three hundred scenarios, EDF's experience in this field is extensive. This practice is well known within Fossil and Nuclear Generation and is well accepted by the operating teams which participate in it. Simulator testing appears to be an essential decision-making tool in the process of developing new operating aids in PWR plants. Accelerated development and the elimination of long and expensive modifications after commissioning is an economic advantage. The saving in time is obvious, since modifications are carried out continuously throughout the development phase. Finally, operators participate in the development of systems and receive fixed, well-defined applications. This practice has become systematic, and all new applications concerning the operation of PWR plants are simulator-tested, particularly 1300-MW unit computers and operating procedures, the new generation of 900-MW unit computers, and the new 1500-MW fully computerized control rooms. Finally, this simulator testing allows us to considerably increase our knowledge concerning the behavior of operators in accident situations, and special tests are performed for this purpose

  14. Finite element simulation of surface defects in the automobile door outer panel

    Fukumura, Masaru; Yamasaki, Yuji; Inage, Daisuke; Fujita, Takashi

    2004-01-01

    Recently, a sheet metal forming simulation has become an indispensable tool for developing a new model of an automobile part within a limited short period. In these days, the utilization of a springback calculation of the formed part has been increasing. However, only a few papers on the prediction of surface defects have been reported in spite of serious needs.In this paper, surface defects in the door outer panel, especially those around the door handle embossment, have been investigated. Applying an explicit solver to the forming simulation, and an implicit solver to the springback calculation, we have tried to evaluate surface defects in the panel. In order to improve the accuracy of the simulation, numerical tools have been modeled including the precise shape of the draw beads so that the draw bead effects on both the material flow and the restraint on the springback deformation have been considered. Compared with the actual panel shape, which shows apparent surface defects, the simulated result has closely predicted the above defects around the embossment.To demonstrate the applicability of our simulation, a few sensitivity analyses have been carried out, modifying forming conditions such as blank holder force. Each result has shown slight but distinctive differences in the cross section profile of the panel. As a result, it has been realized that the influence of each considered factor on surface defects is qualitatively consistent with our practical knowledge

  15. Regulating Power from Supermarket Refrigeration

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

    2014-01-01

    the Danfoss refrigeration test centre. The complexities of modelling demand response are demonstrated through simulation. Simulations are conducted by placing the identified model in a direct-control demand response architecture, with power reference tracking using model predictive control. The energylimited......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...... nature of demand response from refrigeration is identified as the key consideration when considering participation in the regulating power market. It is demonstrated that by restricting the operating regions of the supermarket refrigeration system, a simple relationship can be found between the available...

  16. Numerical simulation of tubes-in-tube heat exchanger in a mixed refrigerant Joule-Thomson cryocooler

    Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

    2017-02-01

    Mixed refrigerant Joule-Thomson (MRJT) cryocoolers can produce cryogenic temperatures with high efficiency and low operating pressures. As compared to the high system pressures of around 150-200 bar with nitrogen, the operational pressures with non-azeotropic mixtures (e.g., nitrogen-hydrocarbons) come down to 10-25 bar. With mixtures, the heat transfer in the recuperative heat exchanger takes place in the two-phase region. The simultaneous boiling and condensation of the cold and hot gas streams lead to higher heat transfer coefficients as compared to single phase heat exchange. The two-phase heat transfer in the recuperative heat exchanger drastically affects the performance of a MRJT cryocooler. In this work, a previously reported numerical model for a simple tube-in-tube heat exchanger is extended to a multi tubes-in-tube heat exchanger with a transient formulation. Additionally, the J-T expansion process is also considered to simulate the cooling process of the heat exchanger from ambient temperature conditions. A tubes-in-tube heat exchanger offers more heat transfer area per unit volume resulting in a compact design. Also, the division of flow in multiple tubes reduces the pressure drop in the heat exchanger. Simulations with different mixtures of nitrogen-hydrocarbons are carried out and the numerical results are compared with the experimental data.

  17. Numerical simulation of the knotted nylon netting panel

    Li Yuwei

    2016-01-01

    Full Text Available A piece of netting, consists of the 8 8 meshes, fixed on a square frame, was simulated and the tensions and their distribution, the positions of knots and netting shape were calculated by means of MATLAB in computer. The dynamic mathematic model was developed based on lumped mass method, the netting was treated as spring-mass system, the Runge-Kutta fifth-order and sixth-order method was used to solve the differential equations for every step, then the displacement and tension of each mass point were obtained. For verify this model, the tests have been carried out in a flume tank. The results of the numerical simulation fully agreed with the experiments.

  18. Simulations of the Yawed MEXICO Rotor Using a Viscous-Inviscid Panel Method

    Ramos García, Néstor; Sørensen, Jens Nørkær; Shen, Wen Zhong

    2014-01-01

    In the present work the viscous-inviscid interactive model MIRAS is used to simulate flows past the MEXICO rotor in yawed conditions. The solver is based on an unsteady three-dimensional free wake panel method which uses a strong viscous-inviscid interaction technique to account for the viscous...

  19. CFD Simulation of Turbulent Wind Effect on an Array of Ground-Mounted Solar PV Panels

    Irtaza, Hassan; Agarwal, Ashish

    2018-02-01

    Aim of the present study is to determine the wind loads on the PV panels in a solar array since panels are vulnerable to high winds. Extensive damages of PV panels, arrays and mounting modules have been reported the world over due to high winds. Solar array of dimension 6 m × 4 m having 12 PV panels of size 1 m × 2 m on 3D 1:50 scaled models have been simulated using unsteady solver with Reynolds-Averaged Navier-Stokes equations of computational fluid dynamics techniques to study the turbulent wind effects on PV panels. A standalone solar array with 30° tilt angle in atmospheric surface layer with the Renormalized Group (RNG) turbulence closure subjected to incident wind varied from - 90° to 90°. The net pressure, drag and lift coefficients are found to be maximum when the wind is flowing normally to the PV panel either 90° or - 90°. The tilt angle of solar arrays the world over not vary on the latitude but also on the seasons. Keeping this in mind the ground mounted PV panels in array with varying tilt angle from 10° to 60° at an interval of 10° have been analyzed for normal wind incident i.e. 90° and - 90° using unsteady RNG turbulence model. Net pressure coefficients have been calculated and found to be increasing with increase in array tilting angle. Maximum net pressure coefficient was observed for the 60° tilted PV array for 90° and - 90° wind incident having value of 0.938 and 0.904 respectively. The results can be concluded that the PV panels are subjected to significant lift and drag forces under wind loading, which needs to be quantified with sufficient factor of safety to avoid damages.

  20. CFD Simulation of Turbulent Wind Effect on an Array of Ground-Mounted Solar PV Panels

    Irtaza, Hassan; Agarwal, Ashish

    2018-06-01

    Aim of the present study is to determine the wind loads on the PV panels in a solar array since panels are vulnerable to high winds. Extensive damages of PV panels, arrays and mounting modules have been reported the world over due to high winds. Solar array of dimension 6 m × 4 m having 12 PV panels of size 1 m × 2 m on 3D 1:50 scaled models have been simulated using unsteady solver with Reynolds-Averaged Navier-Stokes equations of computational fluid dynamics techniques to study the turbulent wind effects on PV panels. A standalone solar array with 30° tilt angle in atmospheric surface layer with the Renormalized Group (RNG) turbulence closure subjected to incident wind varied from - 90° to 90°. The net pressure, drag and lift coefficients are found to be maximum when the wind is flowing normally to the PV panel either 90° or - 90°. The tilt angle of solar arrays the world over not vary on the latitude but also on the seasons. Keeping this in mind the ground mounted PV panels in array with varying tilt angle from 10° to 60° at an interval of 10° have been analyzed for normal wind incident i.e. 90° and - 90° using unsteady RNG turbulence model. Net pressure coefficients have been calculated and found to be increasing with increase in array tilting angle. Maximum net pressure coefficient was observed for the 60° tilted PV array for 90° and - 90° wind incident having value of 0.938 and 0.904 respectively. The results can be concluded that the PV panels are subjected to significant lift and drag forces under wind loading, which needs to be quantified with sufficient factor of safety to avoid damages.

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

    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)

  2. Simulation of an air conditioning absorption refrigeration system in a co-generation process combining a proton exchange membrane fuel cell

    Pilatowsky, I.; Gamboa, S.A.; Rivera, W. [Centro de Investigacion en Energia - UNAM, Temixco, Morelos (Mexico); Romero, R.J. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas - UAEM, Cuernavaca, Morelos (Mexico); Isaza, C.A. [Universidad Pontificia Bolivariana, Medellin (Colombia). Instituto de Energia y Termodinamica; Sebastian, P.J. [Centro de Investigacion en Energia - UNAM, Temixco, Morelos (Mexico); Cuerpo Academico de Energia y Sustentabilidad-UP Chiapas, Tuxtla Gutierrez, Chiapas (Mexico); Moreira, J. [Cuerpo Academico de Energia y Sustentabilidad-UP Chiapas, Tuxtla Gutierrez, Chiapas (Mexico)

    2007-10-15

    In this work, a computer simulation program was developed to determine the optimum operating conditions of an air conditioning system during the co-generation process. A 1 kW PEMFC was considered in this study with a chemical/electrical theoretical efficiency of 40% and a thermal efficiency of 30% applying an electrical load of 100%. A refrigeration-absorption cycle (RAC) operating with monomethylamine-water solutions (MMA-WS), with low vapor generation temperatures (up to 80 C) is proposed in this work. The computer simulation was based on the refrigeration production capacity at the maximum power capacity of the PEMFC. Heat losses between the fuel cell and the absorption air conditioning system at standard operating conditions were considered to be negligible. The results showed the feasibility of using PEMFC for cooling, increasing the total efficiency of the fuel cell system. (author)

  3. Recent investigations on refrigerants for magnetic refrigerators

    Hashimoto, T.

    1986-01-01

    In development of the magnetic refrigerator, an important problem is selection of magnetic materials as refrigerants. The main purpose of the present paper is to discuss the magnetic and thermal properties necessary for these refrigerants and to report recent investigations. Magnetic refrigerants can be expediently divided into two groups, one for the Carnottype magnetic refrigerator below 20 K and the other for the Ericsson-type refrigerator. The required physical properties of refrigerants in each type of the magnetic refrigerator are first discussed. And then, the results of recent investigations on the magnetic, thermal and magnetocaloric characters of several promising magnetic refrigerants are shown. Finally, a brief prospect of the magnetic refrigerants and refrigerators is given

  4. 2014 German refrigeration and air conditioning meeting. Proceedings

    2014-01-01

    The proceedings of the 2014 German refrigeration and air conditioning meeting contain contributions on the following topics: cryotechnology, fundamentals and materials for the refrigeration and heat pump technology, devices and components for the refrigeration and heat pump technology, applications of refrigeration technologies, air conditioning technology and heat pump applications, cryotechnology in biology and medicine, heat transfer and ventilation, guidelines and legal topics, refrigerant fluid - oil mixtures, control and surveillance, simulation and control, ambient air.

  5. Numerical simulation study on rolling-chemical milling process of aluminum-lithium alloy skin panel

    Huang, Z. B.; Sun, Z. G.; Sun, X. F.; Li, X. Q.

    2017-09-01

    Single curvature parts such as aircraft fuselage skin panels are usually manufactured by rolling-chemical milling process, which is usually faced with the problem of geometric accuracy caused by springback. In most cases, the methods of manual adjustment and multiple roll bending are used to control or eliminate the springback. However, these methods can cause the increase of product cost and cycle, and lead to material performance degradation. Therefore, it is of significance to precisely control the springback of rolling-chemical milling process. In this paper, using the method of experiment and numerical simulation on rolling-chemical milling process, the simulation model for rolling-chemical milling process of 2060-T8 aluminum-lithium alloy skin was established and testified by the comparison between numerical simulation and experiment results for the validity. Then, based on the numerical simulation model, the relative technological parameters which influence on the curvature of the skin panel were analyzed. Finally, the prediction of springback and the compensation can be realized by controlling the process parameters.

  6. Designing, Modeling, Constructing, and Testing a Flat Panel Speaker and Sound Diffuser for a Simulator

    Dillon, Christina

    2013-01-01

    The goal of this project was to design, model, build, and test a flat panel speaker and frame for a spherical dome structure being made into a simulator. The simulator will be a test bed for evaluating an immersive environment for human interfaces. This project focused on the loud speakers and a sound diffuser for the dome. The rest of the team worked on an Ambisonics 3D sound system, video projection system, and multi-direction treadmill to create the most realistic scene possible. The main programs utilized in this project, were Pro-E and COMSOL. Pro-E was used for creating detailed figures for the fabrication of a frame that held a flat panel loud speaker. The loud speaker was made from a thin sheet of Plexiglas and 4 acoustic exciters. COMSOL, a multiphysics finite analysis simulator, was used to model and evaluate all stages of the loud speaker, frame, and sound diffuser. Acoustical testing measurements were utilized to create polar plots from the working prototype which were then compared to the COMSOL simulations to select the optimal design for the dome. The final goal of the project was to install the flat panel loud speaker design in addition to a sound diffuser on to the wall of the dome. After running tests in COMSOL on various speaker configurations, including a warped Plexiglas version, the optimal speaker design included a flat piece of Plexiglas with a rounded frame to match the curvature of the dome. Eight of these loud speakers will be mounted into an inch and a half of high performance acoustic insulation, or Thinsulate, that will cover the inside of the dome. The following technical paper discusses these projects and explains the engineering processes used, knowledge gained, and the projected future goals of this project

  7. Solar-Powered Refrigeration System

    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.

  8. Maximum Simulated Likelihood and Expectation-Maximization Methods to Estimate Random Coefficients Logit with Panel Data

    Cherchi, Elisabetta; Guevara, Cristian

    2012-01-01

    with cross-sectional or with panel data, and (d) EM systematically attained more efficient estimators than the MSL method. The results imply that if the purpose of the estimation is only to determine the ratios of the model parameters (e.g., the value of time), the EM method should be preferred. For all......The random coefficients logit model allows a more realistic representation of agents' behavior. However, the estimation of that model may involve simulation, which may become impractical with many random coefficients because of the curse of dimensionality. In this paper, the traditional maximum...... simulated likelihood (MSL) method is compared with the alternative expectation- maximization (EM) method, which does not require simulation. Previous literature had shown that for cross-sectional data, MSL outperforms the EM method in the ability to recover the true parameters and estimation time...

  9. Interaction of a Mach 2.25 turbulent boundary layer with a fluttering panel using direct numerical simulation

    Bodony, Daniel; Ostoich, Christopher; Geubelle, Philippe

    2013-11-01

    The interaction between a thin metallic panel and a Mach 2.25 turbulent boundary layer is investigated using a direct numerical simulation approach for coupled fluid-structure problems. The solid solution uses a finite-strain, finite-deformation formulation, while the direct numerical simulation of the boundary layer uses a finite-difference compressible Navier-Stokes solver. The initially laminar boundary layer contains low amplitude unstable eigenmodes that grow in time and excite traveling bending waves in the panel. As the boundary layer transitions to a fully turbulent state, with Reθ ~ 1200 , the panel's bending waves coalesce into a standing wave pattern exhibiting flutter with a final amplitude approximately 20 times the panel thickness. The corresponding panel deflection is roughly 25 wall units and reaches across the sonic line in the boundary layer profile. Once it reaches a limit cycle state, the panel/boundary layer system is examined in detail where it is found that turbulence statistics, especially the main Reynolds stress - , appear to be modified by the presence of the compliant panel, the effect of which is forgotten within one integral length downstream of the panel. Supported by the U.S. Air Force Research Laboratory Air Vehicles Directorate under contract number FA8650-06-2-3620.

  10. Improving the energy efficiency of industrial refrigeration systems

    Oh, Jin-Sik; Binns, Michael; Park, Sangmin; Kim, Jin-Kuk

    2016-01-01

    Various retrofit design options are available for improving the energy efficiency and economics of industrial refrigeration systems. This study considers a novel retrofit option using a mixed refrigerant (MR) in refrigeration cycles designed for use with a pure refrigerant (PR). In this way energy savings can be realized by switching refrigerants without requiring extensive and expensive reconfiguration of equipment. Hence, the aim here is to test the common thinking that equipment should always be extensively reconfigured when switching from pure to mixed refrigerants. To determine the most energy-efficient operating conditions for each refrigeration design an optimization framework is utilized linking a process simulator with an external optimization method. A case study is presented to demonstrate how the proposed process modeling and optimization framework can be applied and to illustrate the economic benefits of using the retrofit design options considered here. For the case considered in this paper, savings of shaft power required for the refrigeration cycle can be achieved from 16.3% to 27.2% when the pure refrigerant is replaced with mixed refrigerants and operating conditions are re-optimized. - Highlights: • Design methods for the design of refrigeration cycles in retrofit cases. • Consideration of mixed refrigerants to the existing multi-level pure-refrigerant cycles. • Optimization of refrigeration cycles with integrated use of a process simulator with an optimizer.

  11. Design, Simulation and Experimental Investigation of a Solar System Based on PV Panels and PVT Collectors

    Annamaria Buonomano

    2016-06-01

    Full Text Available This paper presents numerical and experimental analyses aimed at evaluating the technical and economic feasibility of photovoltaic/thermal (PVT collectors. An experimental setup was purposely designed and constructed in order to compare the electrical performance of a PVT solar field with the one achieved by an identical solar field consisting of conventional photovoltaic (PV panels. The experimental analysis also aims at evaluating the potential advantages of PVT vs. PV in terms of enhancement of electrical efficiency and thermal energy production. The installed experimental set-up includes four flat polycrystalline silicon PV panels and four flat unglazed polycrystalline silicon PVT collectors. The total electrical power and area of the solar field are 2 kWe and 13 m2, respectively. The experimental set-up is currently installed at the company AV Project Ltd., located in Avellino (Italy. This study also analyzes the system from a numerical point of view, including a thermo-economic dynamic simulation model for the design and the assessment of energy performance and economic profitability of the solar systems consisting of glazed PVT and PV collectors. The experimental setup was modelled and partly simulated in TRNSYS environment. The simulation model was useful to analyze efficiencies and temperatures reached by such solar technologies, by taking into account the reference technology of PVTs (consisting of glazed collectors as well as to compare the numerical data obtained by dynamic simulations with the gathered experimental results for the PV technology. The numerical analysis shows that the PVT global efficiency is about 26%. Conversely, from the experimental point of view, the average thermal efficiency of PVT collectors is around 13% and the electrical efficiencies of both technologies are almost coincident and equal to 15%.

  12. Stirling Refrigerator

    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.

  13. ARTI refrigerant database

    Calm, J.M.

    1998-03-15

    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 thermophysical properties, 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. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air conditioning and refrigeration equipment. It also references documents addressing compatibility of refrigerants and lubricants with other materials.

  14. ARTI refrigerant database

    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.

  15. ARTI refrigerant database

    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.

  16. ARTI refrigerant database

    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.

  17. Proceedings of the 1993 non-fluorocarbon insulation, refrigeration and air conditioning technology workshop

    1994-09-01

    Sessions included: HFC blown polyurethanes, carbon dioxide blown foam and extruded polystyrenes, plastic foam insulations, evacuated panel insulation, refrigeration and air conditioning, absorption and adsorption and stirling cycle refrigeration, innovative cooling technologies, and natural refrigerants. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  18. Experimental Validation of the Simulation Model of a DOAS Equipped with a Desiccant Wheel and a Vapor Compression Refrigeration System

    Pedro J. Martínez

    2017-09-01

    Full Text Available A dedicated outdoor air system (DOAS can be designed to supply 100% of the outside air and meet the latent load of the room with dry air. The objectives of this study were to develop a model of a DOAS equipped with a desiccant wheel and a vapor-compression refrigeration system, build a prototype, validate the model with experimental data, and gain knowledge about the system operation. The test facility was designed with the desiccant wheel downstream of the cooling coil to take advantage of the operating principles of cooling coils and desiccants. A model of the DOAS was developed in the TRNSYS environment. The root mean standard error (RMSE was used for model validation by comparing the measured air and refrigerant properties with the corresponding calculated values. The results obtained with the developed model showed that the DOAS was able to maintain an indoor humidity ratio depending on outdoor conditions. Laboratory tests were also used to investigate the effect of changes in the regeneration air temperature and the process airflow rate on the process air humidity ratio at the outlet of the wheel. The results are consistent with the technical literature.

  19. Time domain simulation of the response of geometrically nonlinear panels subjected to random loading

    Moyer, E. Thomas, Jr.

    1988-01-01

    The response of composite panels subjected to random pressure loads large enough to cause geometrically nonlinear responses is studied. A time domain simulation is employed to solve the equations of motion. An adaptive time stepping algorithm is employed to minimize intermittent transients. A modified algorithm for the prediction of response spectral density is presented which predicts smooth spectral peaks for discrete time histories. Results are presented for a number of input pressure levels and damping coefficients. Response distributions are calculated and compared with the analytical solution of the Fokker-Planck equations. RMS response is reported as a function of input pressure level and damping coefficient. Spectral densities are calculated for a number of examples.

  20. Simulations of the Yawed MEXICO Rotor Using a Viscous-Inviscid Panel Method

    Ramos-García, N; Sørensen, J N; Shen, W Z

    2014-01-01

    In the present work the viscous-inviscid interactive model MIRAS is used to simulate flows past the MEXICO rotor in yawed conditions. The solver is based on an unsteady three-dimensional free wake panel method which uses a strong viscous-inviscid interaction technique to account for the viscous effects inside the boundary layer. Calculated wake velocities have been benchmarked against field PIV measurements, while computed blade aerodynamic characteristics are compared against the load calculated from pressure measurements at different locations along the blade span. Predicted and measured aerodynamic forces are in overall good agreement, however discrepancies appear in the root region which could be related to an underestimation of the rotational effects arising from Coriolis and centrifugal forces. The predicted wake velocities are generally in good agreement with measurements along the radial as well as the axial traverses performed during the experimental campaign

  1. Simulation of Solar Heat Pump Dryer Directly Driven by Photovoltaic Panels

    Houhou, H.; Yuan, W.; Wang, G.

    2017-05-01

    This paper investigates a new type of solar heat pump dryer directly driven by photovoltaic panels. In order to design this system, a mathematical model has been established describing the whole drying process, including models of key components and phenomena of heat and mass transfer at the product layer and the air. The results of simulation at different drying air temperatures and velocities have been calculated and it indicate that the temperature of drying air is crucial external parameter compared to the velocity, with the increase of drying temperature from 45°C to 55°C, the product moisture content (Kg water/Kg dry product) decreased from 0.75 Kg/Kg to 0.3 Kg/Kg.

  2. Modelling of scintillator based flat-panel detectors with Monte-Carlo simulations

    Reims, N; Sukowski, F; Uhlmann, N

    2011-01-01

    Scintillator based flat panel detectors are state of the art in the field of industrial X-ray imaging applications. Choosing the proper system and setup parameters for the vast range of different applications can be a time consuming task, especially when developing new detector systems. Since the system behaviour cannot always be foreseen easily, Monte-Carlo (MC) simulations are keys to gain further knowledge of system components and their behaviour for different imaging conditions. In this work we used two Monte-Carlo based models to examine an indirect converting flat panel detector, specifically the Hamamatsu C9312SK. We focused on the signal generation in the scintillation layer and its influence on the spatial resolution of the whole system. The models differ significantly in their level of complexity. The first model gives a global description of the detector based on different parameters characterizing the spatial resolution. With relatively small effort a simulation model can be developed which equates the real detector regarding signal transfer. The second model allows a more detailed insight of the system. It is based on the well established cascade theory, i.e. describing the detector as a cascade of elemental gain and scattering stages, which represent the built in components and their signal transfer behaviour. In comparison to the first model the influence of single components especially the important light spread behaviour in the scintillator can be analysed in a more differentiated way. Although the implementation of the second model is more time consuming both models have in common that a relatively small amount of system manufacturer parameters are needed. The results of both models were in good agreement with the measured parameters of the real system.

  3. Method and refrigerants for replacing existing refrigerants in centrifugal compressors

    Kopko, W.L.

    1991-01-01

    This patent describes a method for replacing an existing refrigerant in a centrifugal compressor. It comprises selecting a desired impeller Mach number for the centrifugal compressor; selecting a base refrigerant constituent; combining at least one additive refrigerant constituent with the base refrigerant constituent to form a replacement refrigerant having at least one physical or chemical property different from the existing refrigerant and substantially providing the desired impeller Mach number in the centrifugal compressor; and replacing the existing refrigerant with the replacement refrigerant

  4. Influence of the spectral distribution of light on the characteristics of photovoltaic panel. Comparison between simulation and experimental

    Chadel, Meriem; Bouzaki, Mohammed Moustafa; Chadel, Asma; Petit, Pierre; Sawicki, Jean-Paul; Aillerie, Michel; Benyoucef, Boumediene

    2017-02-01

    We present and analyze experimental results obtained with a laboratory setup based on a hardware and smart instrumentation for the complete study of performance of PV panels using for illumination an artificial radiation source (Halogen lamps). Associated to an accurate analysis, this global experimental procedure allows the determination of effective performance under standard conditions thanks to a simulation process originally developed under Matlab software environment. The uniformity of the irradiated surface was checked by simulation of the light field. We studied the response of standard commercial photovoltaic panels under enlightenment measured by a spectrometer with different spectra for two sources, halogen lamps and sunlight. Then, we bring a special attention to the influence of the spectral distribution of light on the characteristics of photovoltaic panel, that we have performed as a function of temperature and for different illuminations with dedicated measurements and studies of the open circuit voltage and short-circuit current.

  5. Analysis of energy saving performance for household refrigerator with thermal storage of condenser and evaporator

    Cheng, Wen-long; Ding, Miao; Yuan, Xu-dong; Han, Bing-Chuan

    2017-01-01

    Highlights: • A novel refrigerator with both HSC and CSE is proposed. • The operational characteristics of novel refrigerator is analyzed. • The comparison of CSE, HSC and DES refrigerators is analyzed. • DES refrigerator has a largest off-time to on-time ratio of 4.3. • DES refrigerator has the best electrical energy saving performance (32%). - Abstract: The heat transfer performances of evaporators and condensers significantly affect the efficiency of household refrigerators. For enhancing heat transfer of the condensers and evaporators, a novel dual energy storage (DES) refrigerator with both heat storage condenser (HSC) and cold storage evaporator (CSE) is proposed. The performance comparison of three kinds of energy storage refrigerators: HSC refrigerator, CSE refrigerator and DES refrigerator is analyzed by establishing dynamic simulation models. According to the simulation results, the DES refrigerator combines the advantage of HSC refrigerator and CSE refrigerator, it has more balanced operational cycle and higher evaporation pressure and temperature. The DES refrigerator shows a best energy saving performance among the three energy storage refrigerators with largest off-time to on-time ratio of 4.3 and the electrical consumption saving can reach 32%, which is greater than the sum (28%) of the other two kinds of energy storage refrigerators.

  6. Simulation of Detecting Damage in Composite Stiffened Panel Using Lamb Waves

    Wang, John T.; Ross, Richard W.; Huang, Guo L.; Yuan, Fuh G.

    2013-01-01

    Lamb wave damage detection in a composite stiffened panel is simulated by performing explicit transient dynamic finite element analyses and using signal imaging techniques. This virtual test process does not need to use real structures, actuators/sensors, or laboratory equipment. Quasi-isotropic laminates are used for the stiffened panels. Two types of damage are studied. One type is a damage in the skin bay and the other type is a debond between the stiffener flange and the skin. Innovative approaches for identifying the damage location and imaging the damage were developed. The damage location is identified by finding the intersection of the damage locus and the path of the time reversal wave packet re-emitted from the sensor nodes. The damage locus is a circle that envelops the potential damage locations. Its center is at the actuator location and its radius is computed by multiplying the group velocity by the time of flight to damage. To create a damage image for estimating the size of damage, a group of nodes in the neighborhood of the damage location is identified for applying an image condition. The image condition, computed at a finite element node, is the zero-lag cross-correlation (ZLCC) of the time-reversed incident wave signal and the time reversal wave signal from the sensor nodes. This damage imaging process is computationally efficient since only the ZLCC values of a small amount of nodes in the neighborhood of the identified damage location are computed instead of those of the full model.

  7. Transition to New Refrigerants

    Overview page provides information on the refrigerants that motor vehicle air conditioners have used over time, with information on environmental impacts, refrigerant fitting sizes, label colors, and alternatives to ozone-depleting substances.

  8. ARTI Refrigerant Database

    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.

  9. Computer modeling of commercial refrigerated warehouse facilities

    Nicoulin, C.V.; Jacobs, P.C.; Tory, S.

    1997-01-01

    The use of computer models to simulate the energy performance of large commercial refrigeration systems typically found in food processing facilities is an area of engineering practice that has seen little development to date. Current techniques employed in predicting energy consumption by such systems have focused on temperature bin methods of analysis. Existing simulation tools such as DOE2 are designed to model commercial buildings and grocery store refrigeration systems. The HVAC and Refrigeration system performance models in these simulations tools model equipment common to commercial buildings and groceries, and respond to energy-efficiency measures likely to be applied to these building types. The applicability of traditional building energy simulation tools to model refrigerated warehouse performance and analyze energy-saving options is limited. The paper will present the results of modeling work undertaken to evaluate energy savings resulting from incentives offered by a California utility to its Refrigerated Warehouse Program participants. The TRNSYS general-purpose transient simulation model was used to predict facility performance and estimate program savings. Custom TRNSYS components were developed to address modeling issues specific to refrigerated warehouse systems, including warehouse loading door infiltration calculations, an evaporator model, single-state and multi-stage compressor models, evaporative condenser models, and defrost energy requirements. The main focus of the paper will be on the modeling approach. The results from the computer simulations, along with overall program impact evaluation results, will also be presented

  10. Environmentally benign working pairs for adsorption refrigeration

    Cui Qun; Tao Gang; Chen Haijun; Guo Xinyue; Yao Huqing

    2005-01-01

    This paper begins from adsorption working pairs: water and ethanol were selected as refrigerants; 13x molecular sieve, silica gel, activated carbon, adsorbent NA and NB, proposed by authors, were selected as adsorbents, and the performance of adsorption working pairs in adsorption refrigeration cycle was studied. The adsorption isotherms of adsorbents (NA and NB) were obtained by high-vacuum gravimetric method. Desorption properties of adsorbents were analyzed and compared by thermal analysis method. The performance of adsorption refrigeration was studied on simulation device of adsorption refrigeration cycle. After presentation of adsorption isotherms, the thermodynamic performance for their use in adsorption refrigeration system was calculated. The results show: (1) the maximum adsorption capacity of water on adsorbent NA reaches 0.7 kg/kg, and the maximum adsorption capacity of ethanol on adsorbent NB is 0.68 kg/kg, which is three times that of ethanol on activated carbon, (2) the refrigeration capacity of NA-water working pair is 922 kJ/kg, the refrigeration capacity of NB-ethanol is 2.4 times that of activated carbon-methanol, (3) as environmental friendly and no public hazard adsorption working pair, NA-H 2 O and NB-ethanol can substitute activated carbon-methanol in adsorption refrigeration system using low-grade heat source

  11. Assessing type I error and power of multistate Markov models for panel data-A simulation study.

    Cassarly, Christy; Martin, Renee' H; Chimowitz, Marc; Peña, Edsel A; Ramakrishnan, Viswanathan; Palesch, Yuko Y

    2017-01-01

    Ordinal outcomes collected at multiple follow-up visits are common in clinical trials. Sometimes, one visit is chosen for the primary analysis and the scale is dichotomized amounting to loss of information. Multistate Markov models describe how a process moves between states over time. Here, simulation studies are performed to investigate the type I error and power characteristics of multistate Markov models for panel data with limited non-adjacent state transitions. The results suggest that the multistate Markov models preserve the type I error and adequate power is achieved with modest sample sizes for panel data with limited non-adjacent state transitions.

  12. Dynamic simulation of natural convection bypass two-circuit cycle refrigerator-freezer and its application Part I: Component models

    Ding Guoliang; Zhang Chunlu; Lu Zhili

    2004-01-01

    In order to reduce the greenhouse gas emissions, efficient household refrigerator/freezers (RFs) are required. Bypass two-circuit cycle RFs with one compressor are proved to be more efficient than two-evaporator in series cycle RFs. In order to study the characteristics and improve the design of bypass two-circuit cycle RFs, a dynamic model is developed in this paper. In part I, the mathematic models of all components are presented, considering not only the accuracy of the models but also the computation stability and speed to solve the models. An efficiency model that requires a single calorimeter data point at the standard test condition is employed for compressor. A multi-zone model is employed for condenser and for evaporator, with its wall thermal capacity considered by effective metal method. The approximate integral analytic model is employed for adiabatic capillary tube, and the effective inlet enthalpy method is used to transfer the non-adiabatic capillary tube to adiabatic capillary tube. The z-transfer function model is employed for cabinet load calculation

  13. 2014 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte- und Klimatagung 2014. Tagungsbericht

    NONE

    2014-07-01

    The proceedings of the 2014 German refrigeration and air conditioning meeting contain contributions on the following topics: cryotechnology, fundamentals and materials for the refrigeration and heat pump technology, devices and components for the refrigeration and heat pump technology, applications of refrigeration technologies, air conditioning technology and heat pump applications, cryotechnology in biology and medicine, heat transfer and ventilation, guidelines and legal topics, refrigerant fluid - oil mixtures, control and surveillance, simulation and control, ambient air.

  14. Lightweight, Thermally Insulating Structural Panels

    Eisen, Howard J.; Hickey, Gregory; Wen, Liang-Chi; Layman, William E.; Rainen, Richard A.; Birur, Gajanana C.

    1996-01-01

    Lightweight, thermally insulating panels that also serve as structural members developed. Honeycomb-core panel filled with low-thermal-conductivity, opacified silica aerogel preventing convection and minimizes internal radiation. Copper coating on face sheets reduces radiation. Overall thermal conductivities of panels smaller than state-of-art commercial non-structurally-supporting foam and fibrous insulations. On Earth, panels suitable for use in low-air-pressure environments in which lightweight, compact, structurally supporting insulation needed; for example, aboard high-altitude aircraft or in partially evacuated panels in refrigerators.

  15. Theoretical study on a novel dual-nozzle ejector enhanced refrigeration cycle for household refrigerator-freezers

    Zhou, Mengliu; Wang, Xiao; Yu, Jianlin

    2013-01-01

    Highlights: • A novel dual-nozzle ejector enhanced refrigeration cycle is proposed. • The novel cycle is evaluated by using the developed mathematical model. • The results show the performances of the novel cycle could be significantly improved. • The novel cycle shows its promise in household refrigerator-freezers applications. - Abstract: In this study, a novel dual-nozzle ejector enhanced refrigeration cycle is presented for dual evaporator household refrigerator-freezers. The proposed ejector equipped with two nozzles can efficiently recover the expansion work from cycle throttling processes and enhance cycle performances. The performances of the novel cycle are evaluated by using the developed mathematical model, and then compared with that of the conventional ejector enhanced refrigeration cycle and basic vapor-compression refrigeration cycle. The simulation results show that for the given operating conditions, the coefficient of performance (COP) of the novel cycle using refrigerant R134a is improved by 22.9–50.8% compared with that of the basic vapor-compression refrigeration cycle, and the COP improvement is 10.5–30.8% larger than that of the conventional ejector enhanced refrigeration cycle. The further simulation results of the novel cycle using refrigerant R600a indicate that the cycle COP and volumetric refrigeration capacity could be significantly improved

  16. Magnetic refrigerator for hydrogen liquefaction

    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.

  17. ARTI refrigerant database

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

    1996-04-15

    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. 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 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. Citations in this report are divided into the following topics: thermophysical properties; materials compatibility; lubricants and tribology; application data; safety; test and analysis methods; impacts; regulatory actions; substitute refrigerants; identification; absorption and adsorption; research programs; and miscellaneous documents. Information is also presented on ordering instructions for the computerized version.

  18. Assessing type I error and power of multistate Markov models for panel data-A simulation study

    Cassarly, Christy; Martin, Renee’ H.; Chimowitz, Marc; Peña, Edsel A.; Ramakrishnan, Viswanathan; Palesch, Yuko Y.

    2016-01-01

    Ordinal outcomes collected at multiple follow-up visits are common in clinical trials. Sometimes, one visit is chosen for the primary analysis and the scale is dichotomized amounting to loss of information. Multistate Markov models describe how a process moves between states over time. Here, simulation studies are performed to investigate the type I error and power characteristics of multistate Markov models for panel data with limited non-adjacent state transitions. The results suggest that ...

  19. Developments in magnetocaloric refrigeration

    Brueck, Ekkes

    2005-01-01

    Modern society relies on readily available refrigeration. Magnetic refrigeration has three prominent advantages compared with compressor-based refrigeration. First, there are no harmful gases involved; second, it may be built more compactly as the working material is a solid; and third, magnetic refrigerators generate much less noise. Recently a new class of magnetic refrigerant-materials for room-temperature applications was discovered. These new materials have important advantages over existing magnetic coolants: they exhibit a large magnetocaloric effect (MCE) in conjunction with a magnetic phase-transition of first order. This MCE is larger than that of Gd metal, which is used in the demonstration refrigerators built to explore the potential of this evolving technology. In the present review we compare the different materials considering both scientific aspects and industrial applicability. Because fundamental aspects of MCE are not so widely discussed, we also give some theoretical considerations. (topical review)

  20. WTEC Panel Report on International Assessment of Research and Development in Simulation-Based Engineering and Science

    Glotzer, S. C.; Kim, S.; Cummings, P. T.; Deshmukh, A.; Head-Gordon, M.; Karniadakis, G.; Petzold, L.; Sagui, C.; Shinozuka, M.

    2013-07-30

    This WTEC panel report assesses the international research and development activities in the field of Simulation- Based Engineering and Science (SBE&S). SBE&S involves the use of computer modeling and simulation to solve mathematical formulations of physical models of engineered and natural systems. SBE&S today has reached a level of predictive capability that it now firmly complements the traditional pillars of theory and experimentation/observation. As a result, computer simulation is more pervasive today – and having more impact – than at any other time in human history. Many critical technologies, including those to develop new energy sources and to shift the cost-benefit factors in healthcare, are on the horizon that cannot be understood, developed, or utilized without simulation. A panel of experts reviewed and assessed the state of the art in SBE&S as well as levels of activity overseas in the broad thematic areas of life sciences and medicine, materials, and energy and sustainability; and in the crosscutting issues of next generation hardware and algorithms; software development; engineering simulations; validation, verification, and uncertainty quantification; multiscale modeling and simulation; and SBE&S education. The panel hosted a U.S. baseline workshop, conducted a bibliometric analysis, consulted numerous experts and reports, and visited 59 institutions and companies throughout East Asia and Western Europe to explore the active research projects in those institutions, the computational infrastructure used for the projects, the funding schemes that enable the research, the collaborative interactions among universities, national laboratories, and corporate research centers, and workforce needs and development for SBE&S.

  1. Ultimate refrigerating conditions, behavior turning and a thermodynamic analysis for absorption–compression hybrid refrigeration cycle

    Zheng Danxing; Meng Xuelin

    2012-01-01

    Highlights: ► Two novel fundamental concepts of the absorption refrigeration cycle were proposed. ► The interaction mechanism of compressor pressure increasing with other key-parameters was investigated. ► A set of optimal operating condition of hybrid refrigeration cycle was found. ► A simulation and investigation for R134a-DMF hybrid refrigeration cycle was performed. - Abstract: The absorption–compression hybrid refrigeration cycle has been considered as an effective approach to reduce the mechanical work consumption by using low-grade heat, such as solar energy. This work aims at studying the thermodynamic mechanism of the hybrid refrigeration cycle. Two fundamental concepts have been proposed, which are the ultimate refrigerating temperature (or the ultimate temperature lift) and the behavior turning. On the basis of that, the interaction mechanism of compressor pressure increasing with other key-parameters and the impact of compressor pressure increasing on the cycle performance have been investigated. The key-parameters include the concentration difference, the circulation ratio of working fluid, etc. The work points out that the hybrid refrigeration cycle performance varies with the change of compressor outlet pressure and depends on which one achieves dominance in the hybrid refrigeration cycle, the absorption sub-system or the compression sub-system. The behavior turning point during parameters changing corresponds to a maximum value of the heat powered coefficient of performance. In this case, the hybrid refrigeration cycle performance is optimal because the low-grade heat utilization is the most effective. In addition, to validate the theoretical analysis, a solar hybrid refrigeration cycle with R134a–DMF as working pair was simulated. The Peng–Robinson equation of state was adopted to calculate thermophysical properties when the reliability assessment of the prediction models on the available literature data of R134a–DMF system had been

  2. Refrigeration and global warming

    Anon.

    1997-01-01

    Some aspects of global warming in general, and the implications for refrigerants and refrigerator efficiency in particular, are briefly considered in a question and answer format. The concepts of Global Warming Potential (GWP) and Total Equivalent Warming Impact (TEWI) are explained. GWP is an index which allows a simple comparison to be make between the warming effects of different gases on a kg to kg basis relative to carbon. The GWP depends both on the lifetime of a substance in the atmosphere and its infra-red absorption capacity. The overall warming effect of operating a refrigeration system for its entire life is measured by its TEWI. Chloroflourocarbons (CFCs) which have been widely used as refrigerants are powerful greenhouse gases with high GWPs. Because of the bank of CFCs in refrigerating systems, their levels in the atmosphere are still increasing and it will be some time before refrigerant changes will be effective in reducing the warming effects of refrigerant releases. Hydrocarbons, hydroflourocarbons and ammonia all have a part to play as substitute refrigerants. Refrigerator efficiency is very important in terms of reducing CO 2 emissions. (UK)

  3. ARTI refrigerant database

    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

    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. Simulator of Cryogenic process and Refrigeration, and its Control in scientific -nuclear facilities with EcosimPro

    Veleiro Blanco, A. M.

    2011-01-01

    The cryogenic plants and their control in Scientific-Nuclear Facilities is complicated by the large number of variables and the wide range of variation during operation. Initially the design and control of these systems in CERN was based on stationary calculations which non yielded the expected results. Due to its complexity, the dynamic simulation is the only way to get adequate results during operational transients.

  6. Make Your Own Solar Panel.

    Suzuki, David

    1992-01-01

    Presents an activity in which students make a simulated solar panel to learn about the principles behind energy production using solar panels. Provides information about how solar panels function to produce energy. (MCO)

  7. Cryogenic mixed refrigerant processes

    Venkatarathnam, Gadhiraju

    2010-01-01

    Teaches the need for refrigerant mixtures, the type of mixtures that can be used for different refrigeration and liquefaction applications, the different processes that can be used and the methods to be adopted for choosing the components of a mixture and their concentration for different applications.

  8. A sheet metal forming simulation of automotive outer panels considering the behavior of air in die cavity

    Choi, Kwang Yong; Kim, Yun Chang; Choi, Hee Kwan; Kang, Chul Ho; Kim, Heon Young

    2013-12-01

    During a sheet metal forming process of automotive outer panels, the air trapped between a blank sheet and a die tool can become highly compressed, ultimately influencing the blank deformation and the press force. To prevent this problem, vent holes are drilled into die tools and needs several tens to hundreds according to the model size. The design and the drilling of vent holes are based on expert's experience and try-out result and thus the process can be one of reasons increasing development cycle. Therefore the study on the size, the number, and the position of vent holes is demanded for reducing development cycle, but there is no simulation technology for analyzing forming defects, making numerical sheet metal forming process simulations that incorporate the fluid dynamics of air. This study presents a sheet metal forming simulation of automotive outer panels (a roof and a body side outer) that simultaneously simulates the behavior of air in a die cavity. Through CAE results, the effect of air behavior and vent holes to blank deformation was analyzed. For this study, the commercial software PAM-STAMP{trade mark, serif} and PAM-SAFE{trade mark, serif} was used.

  9. Refrigerants and environment

    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.

  10. Simulation study of air and water cooled photovoltaic panel using ANSYS

    Syafiqah, Z.; Amin, N. A. M.; Irwan, Y. M.; Majid, M. S. A.; Aziz, N. A.

    2017-10-01

    Demand for alternative energy is growing due to decrease of fossil fuels sources. One of the promising and popular renewable energy technology is a photovoltaic (PV) technology. During the actual operation of PV cells, only around 15% of solar irradiance is converted to electricity, while the rest is converted into heat. The electrical efficiency decreases with the increment in PV panel’s temperature. This electrical energy is referring to the open-circuit voltage (Voc), short-circuit current (Isc) and output power generate. This paper examines and discusses the PV panel with water and air cooling system. The air cooling system was installed at the back of PV panel while water cooling system at front surface. The analyses of both cooling systems were done by using ANSYS CFX and PSPICE software. The highest temperature of PV panel without cooling system is 66.3 °C. There is a decrement of 19.2% and 53.2% in temperature with the air and water cooling system applied to PV panel.

  11. Analysis of Refrigeration Cycle Performance with an Ejector

    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.

  12. Modeling and calculation of open carbon dioxide refrigeration system

    Cai, Yufei; Zhu, Chunling; Jiang, Yanlong; Shi, Hong

    2015-01-01

    Highlights: • A model of open refrigeration system is developed. • The state of CO 2 has great effect on Refrigeration capacity loss by heat transfer. • Refrigeration capacity loss by remaining CO 2 has little relation to the state of CO 2 . • Calculation results are in agreement with the test results. - Abstract: Based on the analysis of the properties of carbon dioxide, an open carbon dioxide refrigeration system is proposed, which is responsible for the situation without external electricity unit. A model of open refrigeration system is developed, and the relationship between the storage environment of carbon dioxide and refrigeration capacity is conducted. Meanwhile, a test platform is developed to simulation the performance of the open carbon dioxide refrigeration system. By comparing the theoretical calculations and the experimental results, several conclusions are obtained as follows: refrigeration capacity loss by heat transfer in supercritical state is much more than that in two-phase region and the refrigeration capacity loss by remaining carbon dioxide has little relation to the state of carbon dioxide. The results will be helpful to the use of open carbon dioxide refrigeration

  13. Improvement of a thermoelectric and vapour compression hybrid refrigerator

    Astrain, D.; Martínez, A.; Rodríguez, A.

    2012-01-01

    This paper presents the improvement in the performance of a domestic hybrid refrigerator that combines vapour compression technology for the cooler and freezer compartments, and thermoelectric technology for a new compartment. The heat emitted by the Peltier modules is discharged into the freezer compartment, forming a cascade refrigeration system. This configuration leads to a significant improvement in the coefficient of operation. Thus, the electric power consumption of the modules and the refrigerator decreases by 95% and 20% respectively, with respect to those attained with a cascade refrigeration system connected with the cooler compartment. The optimization process is based on a computational model that simulates the behaviour of the whole refrigerator. Two prototypes have been built and tested. Experimental results indicate that the temperature of the new compartment is easily set up at any value between 0 and −4 °C, the oscillation of this temperature is always lower than 0.4 °C, and the electric power consumption is low enough to include this hybrid refrigerator into energy efficiency class A, according European rules and regulations. - Highlights: ► Optimization of a vapour compression and thermoelectric hybrid refrigerator. ► Two prototypes built and tested. Computational model for the whole refrigerator. ► Electric power consumption of the modules and the refrigerator 95% and 20% lower. ► New compartment refrigerated with thermoelectric technology. ► Inner temperature adjustable from 0 to −4 °C. Oscillations lower than ±0.2 °C.

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

    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.

  15. Commissioning of a 20 K Helium Refrigeration System for NASA-JSC Chamber A

    Homan, J.; Redman, R.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Norton, R.; Lauterbach, J.; Linza, R.; Vargas, G.

    2013-01-01

    A new 20 K helium refrigerator installed at NASA Johnson Space Center s Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope (JWST). The chamber previously and currently still has helium cryo-pumping panels (CPP) and liquid nitrogen shrouds used to create low earth orbit environments. Now with the new refrigerator and new helium shrouds the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Lab, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate an inverse coefficient of performance better than 70 W/W for a 18 kW load at 20 K (accounting for liquid nitrogen pre-cooling power) that remains essentially constant down to one third of this load. Even at 10 percent of the maximum capacity, the performance is better than 150 W/W at 20 K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10 kW at 15 K to 100 kW at 100 K. The refrigerator is capable of operating at any load temperature from 15 K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

  16. 20 K Helium Refrigeration System for NASA-JSC Chamber-A

    Homan, J.; Redman, R.; Ganni, V.; Sidi-Yekhelef, A.; Knudsen, P.; Norton, R.; Lauterbach, J.; Linza, R.; Vargas, G.

    2013-01-01

    A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope. The chamber previously and currently still has helium cryopumping panels (CPP) and LN2 shrouds used to create Low Earth Orbit environments. Now with the new refrigerator and new helium shrouds (45 x 65 ) the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Labs, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate a inverse coefficient of performance better than 70 W/W for a 18 KW load at 20 K (accounting for liquid nitrogen precooling power) that remains essentially constant down to 1/3 of this load. Even at 10 percent of the maximum capacity, the performance is better than 140 W/W at 20K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10kW at 15 K to 100 kW at 100K. The refrigerator is capable of operating at any load temperature from 15K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

  17. Prediction of thermodynamic properties of refrigerants using data mining

    Kuecueksille, Ecir Ugur; Selbas, Resat; Sencan, Arzu

    2011-01-01

    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.

  18. Control and optimization of the refrigeration plant in a brewery

    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...

  19. Cogeneration in breweries analysis and simulation of systems for simultaneous generation of power, heat and refrigeration using natural gas; Sistemas de refrigeracao a partir da cogeracao: analise e simulacao de propostas para o caso de cervejarias utilizando gas natural

    Gallego, Antonio Garrido

    1998-07-01

    The present work analyses some proposals of cogeneration systems for the simultaneous generation of power, heat and refrigeration in a brewery. The requirements of steam, refrigeration and electricity, as well as the production of beer in a plant of the Antarctica Company, located in Jaguariuna - SP were collected monthly for the year of 1997. Three conceptions of systems using two gas turbines with heat recovery steam generator were then proposed to meet the surveyed demand. The proposals differ in the refrigeration system: the first one uses a traditional ammonia compression system while the second uses an ammonia absorption system, the third proposal is a combination of the compression and absorption systems. These proposals are compared to the present configuration which purchases electricity from the Public Utility for power and refrigeration (using an ammonia compression)system, and fuel oil to generate steam for process heat. The technical, economical and environmental feasibility of the proposals, as well as of the present configuration are discussed on the basis of mass balances, energy balances (first law of Thermodynamics), exergy fluxes (second law analysis), operational and capital cost, based on simulation of the performance of each configuration proposed to meet the monthly electricity, steam and refrigeration requirements for the referred plant. The turbines were chosen so as to meet the peek energy demand of the plant and two cases were simulated for each proposal: turbine operational meets only the demand of the plant and turbine operates at full load, selling electricity for the Public utility. Results obtained show that the current operational costs are higher than any of the proposals presented. The high capital costs of the proposals, though,make them less interesting financially. The simulation of the case of excess electricity to the Public Utility is very attractive, considering the cost of natural gas 3,38 U$/M btu and the fare of 40 U

  20. Development of Low Global Warming Potential Refrigerant Solutions for Commercial Refrigeration Systems using a Life Cycle Climate Performance Design Tool

    Abdelaziz, Omar [ORNL; Fricke, Brian A [ORNL; Vineyard, Edward Allan [ORNL

    2012-01-01

    Commercial refrigeration systems are known to be prone to high leak rates and to consume large amounts of electricity. As such, direct emissions related to refrigerant leakage and indirect emissions resulting from primary energy consumption contribute greatly to their Life Cycle Climate Performance (LCCP). In this paper, an LCCP design tool is used to evaluate the performance of a typical commercial refrigeration system with alternative refrigerants and minor system modifications to provide lower Global Warming Potential (GWP) refrigerant solutions with improved LCCP compared to baseline systems. The LCCP design tool accounts for system performance, ambient temperature, and system load; system performance is evaluated using a validated vapor compression system simulation tool while ambient temperature and system load are devised from a widely used building energy modeling tool (EnergyPlus). The LCCP design tool also accounts for the change in hourly electricity emission rate to yield an accurate prediction of indirect emissions. The analysis shows that conventional commercial refrigeration system life cycle emissions are largely due to direct emissions associated with refrigerant leaks and that system efficiency plays a smaller role in the LCCP. However, as a transition occurs to low GWP refrigerants, the indirect emissions become more relevant. Low GWP refrigerants may not be suitable for drop-in replacements in conventional commercial refrigeration systems; however some mixtures may be introduced as transitional drop-in replacements. These transitional refrigerants have a significantly lower GWP than baseline refrigerants and as such, improved LCCP. The paper concludes with a brief discussion on the tradeoffs between refrigerant GWP, efficiency and capacity.

  1. Numerical Simulation of Aerogasdynamics Processes in A Longwall Panel for Estimation of Spontaneous Combustion Hazards

    Meshkov, Sergey; Sidorenko, Andrey

    2017-11-01

    The relevance of a solution of the problem of endogenous fire safety in seams liable to self-ignition is shown. The possibilities of numerical methods of researches of gasdynamic processes are considered. The analysis of methodical approaches with the purpose to create models and carry out numerical researches of aerogasdynamic processes in longwall panels of gas mines is made. Parameters of the gob for longwall mining are considered. The significant influence of geological and mining conditions of conducting mining operations on distribution of air streams on longwall panels and effective management of gas emission is shown. The aerogasdynamic model of longwall panels for further research of influence of parameters of ventilation and properties of gob is presented. The results of numerical researches including distribution of air streams, fields of concentration of methane and oxygen at application of various schemes of airing for conditions of perspective mines of the Pechora basin and Kuzbass are given. Recommendations for increase of efficiency of the coal seams mining liable to selfignition are made. The directions of further researches are defined.

  2. New energy test procedures for refrigerators and other appliances; FINAL

    Meier, Alan; Ernebrant, Stefan; Kawamoto, Kaoru; Wihlborg, Mats

    1999-01-01

    Many innovations in refrigerator design rely on microprocessors, sensors, and algorithms to control automatic defrost, variable speed,and other features. Even though these features strongly influence energy consumption, the major energy test procedures presently test only a refrigerator's mechanical efficiency and ignore the ''software'' aspects. We describe a new test procedure where both ''hardware'' and ''software'' tests are fed into a dynamic simulation model. A wide range of conditions can be tested and simulated. This approach promotes international harmonization because the simulation model can also be programmed to estimate energy use for the ISO, DOE, or JIS test. The approach outlined for refrigerators can also be applied to other appliances

  3. Computer model of the refrigeration system of an ice rink

    Teyssedou, G.; Zmeureanu, R. [Concordia Univ., Centre for Building Studies, Montreal, PQ (Canada). Dept. of Building, Civil and Environmental Engineering; Giguere, D. [Natural Resources Canada, Varennes, PQ (Canada). CANMET Energy Technology Centre

    2008-07-01

    This paper presented a refrigeration system model of an existing ice rink using a component approach. The chillers, the ice-concrete slab and the controller were the 3 main components used in the simulations which were performed using both open and closed loop systems. The simulated ice rink refrigeration system was based on measurements taken in an existing indoor ice rink located in Montreal, Quebec. Measurements of the refrigeration system included electricity demand; heat flux on the ice sheet; exterior air temperature; ice temperature; return brine temperature; brine temperature at the pump; brine temperature at both evaporator exits; and refrigerant temperature and pressure at the expansion and condenser valve exits. Simulation results and measurements were found to be in good agreement. A computer model of the refrigeration system was developed using the TRNSYS 16 program. The refrigeration system was composed of 2 chillers using refrigerant R-22. The impact of heat recovery from the condensers on the energy demand for sanitary water heating was also estimated. The potential reduction of equivalent carbon dioxide emissions was calculated using the total equivalent warming impact (TEWI) criterion in an effort to estimate the refrigeration impact on global warming. 12 refs., 4 tabs., 12 figs.

  4. Public Refrigerated Warehouses

    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...

  5. Thermoacoustic engines and refrigerators

    Swift, G.

    1996-12-31

    This report is a transcript of a practice lecture given in preparation for a review lecture on the operation of thermoacoustic engines and refrigerators. The author begins by a brief review of the thermodynamic principles underlying the operation of thermoacoustic engines and refrigerators. Remember from thermodynamics class that there are two kinds of heat engines, the heat engine or the prime mover which produces work from heat, and the refrigerator or heat pump that uses work to pump heat. The device operates between two thermal reservoirs at temperatures T{sub hot} and T{sub cold}. In the heat engine, heat flows into the device from the reservoir at T{sub hot}, produces work, and delivers waste heat into the reservoir at T{sub cold}. In the refrigerator, work flows into the device, lifting heat Q{sub cold} from reservoir at T{sub cold} and rejecting waste heat into the reservoir at T{sub hot}.

  6. Refrigerated display cabinets; Butikskyla

    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.

  7. High temperature refrigerator

    Steyert, W.A. Jr.

    1978-01-01

    A high temperature magnetic refrigerator is described which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle the working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot

  8. Refrigeration systems and applications

    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

  9. Influence of the nozzle angle on refrigeration performance of a gas wave refrigerator

    Liu, P.; Zhu, Y.; Wang, H.; Zhu, C.; Zou, J.; Wu, J.; Hu, D.

    2017-05-01

    A gas wave refrigerator (GWR) is a novel refrigerating device that refrigerates a medium by shock waves and expansion waves generated by gas pressure energy. In a typical GWR, the injection energy losses between the nozzle and the expansion tube are essential factors which influence the refrigeration efficiency. In this study, numerical simulations are used to analyze the underlying mechanism of the injection energy losses. The results of simulations show that the vortex loss, mixing energy loss, and oblique shock wave reflection loss are the main factors contributing to the injection energy losses in the expansion tube. Furthermore, the jet angle of the gas is found to dominate the injection energy losses. Therefore, the optimum jet angle is theoretically calculated based on the velocity triangle method. The value of the optimum jet angle is found to be 4^{circ }, 8^{circ }, and 12^{circ } when the refrigeration efficiency is the first-order, second-order, and third-order maximum value over all working ranges of jet frequency, respectively. Finally, a series of experiments are conducted with the jet angle ranging from -4^{circ } to 12^{circ } at a constant expansion ratio. The results indicate the optimal jet angle obtained by the experiments is in good agreement with the calculated value. The isentropic refrigeration efficiency increased by about 4 % after the jet angle was optimized.

  10. Evaluation of Various Retrofitting Concepts of Building Envelope for Offices Equipped with Large Radiant Ceiling Panels by Dynamic Simulations

    Sabina Jordan

    2015-09-01

    Full Text Available In order to achieve significant savings in energy and an improved level of thermal comfort in retrofitted existing buildings, specific retrofitting concepts that combine new technologies and design need to be developed and implemented. Large radiant surfaces systems are now among the most promising future technologies to be used both in retrofitted and in new low-energy buildings. These kinds of systems have been the topic of several studies dealing with thermal comfort and energy utilization, but some specific issues concerning their possible use in various concepts for retrofitting are still poorly understood. In the present paper, some results of dynamic simulations, with the transient system simulation tool (TRNSYS model, of the retrofitted offices equipped with radiant ceiling panels are presented and thoroughly analysed. Based on a precise comparison of the results of these simulations with actual measurements in the offices, certain input data for the model were added, so that the model was consequently validated. The model was then applied to the evaluation of various concepts of building envelopes for office retrofitting. By means of dynamic simulations of indoor environment it was possible to determine the benefits and limitations of individual retrofitting concepts. Some specific parameters, which are relevant to these concepts, were also identified.

  11. Current fluctuations in quantum absorption refrigerators

    Segal, Dvira

    2018-05-01

    Absorption refrigerators transfer thermal energy from a cold bath to a hot bath without input power by utilizing heat from an additional "work" reservoir. Particularly interesting is a three-level design for a quantum absorption refrigerator, which can be optimized to reach the maximal (Carnot) cooling efficiency. Previous studies of three-level chillers focused on the behavior of the averaged cooling current. Here, we go beyond that and study the full counting statistics of heat exchange in a three-level chiller model. We explain how to obtain the complete cumulant generating function of the refrigerator in a steady state, then derive a partial cumulant generating function, which yields closed-form expressions for both the averaged cooling current and its noise. Our analytical results and simulations are beneficial for the design of nanoscale engines and cooling systems far from equilibrium, with their performance optimized according to different criteria, efficiency, power, fluctuations, and dissipation.

  12. Load leveling on industrial refrigeration systems

    Bierenbaum, H. S.; Kraus, A. D.

    1982-01-01

    A computer model was constructed of a brewery with a 2000 horsepower compressor/refrigeration system. The various conservation and load management options were simulated using the validated model. The savings available for implementing the most promising options were verified by trials in the brewery. Result show that an optimized methodology for implementing load leveling and energy conservation consisted of: (1) adjusting (or tuning) refrigeration systems controller variables to minimize unnecessary compressor starts, (2) The primary refrigeration system operating parameters, compressor suction pressure, and discharge pressure are carefully controlled (modulated) to satisfy product quality constraints (as well as in-process material cooling rates and temperature levels) and energy evaluating the energy cost savings associated with reject heat recovery, and (4) a decision is made to implement the reject heat recovery system based on a cost/benefits analysis.

  13. Small variable speed hermetic reciprocating compressors for domestic refrigerators

    Rasmussen, Bjarne D.

    1996-01-01

    This paper contains both a theoretical and experimental investigation of some of the fundamental characteristics of a smal variable speed hermetic reciprocating compressor intended for application in domestic refrigeration. The results of a previously published simulation model for variable speed...

  14. Automatic control study of the icing research tunnel refrigeration system

    Kieffer, Arthur W.; Soeder, Ronald H.

    1991-01-01

    The Icing Research Tunnel (IRT) at the NASA Lewis Research Center is a subsonic, closed-return atmospheric tunnel. The tunnel includes a heat exchanger and a refrigeration plant to achieve the desired air temperature and a spray system to generate the type of icing conditions that would be encountered by aircraft. At the present time, the tunnel air temperature is controlled by manual adjustment of freon refrigerant flow control valves. An upgrade of this facility calls for these control valves to be adjusted by an automatic controller. The digital computer simulation of the IRT refrigeration plant and the automatic controller that was used in the simulation are discussed.

  15. Development of auxiliary shutdown panel for nuclear training center 2 simulator

    Lee, Cheul Un; Lee, Yong Kwan; Cho, Byung Hak; Park, Shin Yeol; Choi, Yong Jae; Kim, Yong Ran [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Sung Il; Lee, Sung Cheul; Ryuh, Kyung Shin [Korea Electric Power Corp. (KEPCO), Seoul (Korea, Republic of)

    1995-12-31

    The major object of the project is to provide emergency operating conditions to the trainees by adding simulated ASP to the existing NTC(Nuclear Training Center) 2 simulator. The other object of the project is to make KEPRI(Korea Electric Power Research Institute) be equipped with a technical know-how that is inevitable to apply its state-of-art technologies to the existing simulators in KEPCO. The contents of this report are as follows : 1. Design and manufacturing of prototype ASP. 2. Manufacturing and installation of full scope ASP. 3. Development and modification of simulator programs. 4. Integration of hardware and software, perform performance acceptance test (author). 22 refs., 9 figs.

  16. Low Global Warming Potential Refrigerants for Commercial Refrigeration Systems

    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

  17. ARTI Refrigerant Database

    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.

  18. Cryogenic forced convection refrigerating system

    Klee, D.J.

    1988-01-01

    This patent describes the method of refrigerating products by contact with a refrigerating gas which comprises introducing product into a refrigeration zone, contacting the product with the refrigerating gas for a sufficient time to refrigerate it to the appropriate extent and removing the refrigerated product. The improvement for producing the refrigeration gas from a liquid cryogen such that essentially all of the liquid cryogen is fully vaporized before contacting the product comprises: (a) introducing the liquid cryogen, selected from the group consisting of liquid air and liquid nitrogen, at elevated pressure into an ejector as the motive fluid to accelerate a portion of a warm refrigerating gas through the ejector while mixing the cryogen and gas to effect complete vaporization of the liquid cryogen and substantial cooling of the portion of the refrigerating gas resulting in a cold discharge gas which is above the liquefaction temperature of the cryogen; (b) introducing the cold discharge gas into a forced circulation pathway of refrigerating gas and producing a cold refrigerating gas which contacts and refrigerates product and is then at least partially recirculated; (c) sensing the temperature of the refrigerating gas in the forced circulation pathway and controlling the introduction of liquid cryogen with regard to the sensed temperature to maintain the temperature of the discharge gas above the liquefacton temperature of the cryogen utilized

  19. Measurement of shear strength resistance in flexion test on PUR sandwich panels: analysis of difficulties and finite element method simulation

    J. M. Chillón Moreno

    2017-09-01

    Full Text Available The use of the composite construction elements combining different materials with complementary characteristics, it has spread increasingly. The sandwich panels composed by external metallic sheets that they contributes resistance and core of rigid insulating thermal foam, that provides qualities that improve the thermal comfort inside all kinds of constructions. They are in use in closings and covers that shape the surrounding one of the buildings. Of the different quality controls to which they have to surrender. In this article one proposes an improvement to the indicated one in the procedure for the determination of the resistance to the shear strength, Managing to avoid many anomalous results obtained by the utilization of rigid plates in the supports. Finally, so much the problem observed as the proposed solution, they are modeled and simulate by means of the method of finite elements.

  20. Indirect refrigeration systems with natural refrigerants

    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 shell......-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....

  1. ARTI Refrigerant Database

    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.

  2. Hybrid vortex simulations of wind turbines using a three-dimensional viscous-inviscid panel method

    Ramos García, Néstor; Hejlesen, Mads Mølholm; Sørensen, Jens Nørkær

    2017-01-01

    adirect calculation, whereas the contribution from the large downstream wake is calculated using a mesh-based method. Thehybrid method is first validated in detail against the well-known MEXICO experiment, using the direct filament method asa comparison. The second part of the validation includes a study......A hybrid filament-mesh vortex method is proposed and validated to predict the aerodynamic performance of wind turbinerotors and to simulate the resulting wake. Its novelty consists of using a hybrid method to accurately simulate the wakedownstream of the wind turbine while reducing...

  3. Refrigeration a history

    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

  4. Analysis of the effects of simulated synergistic LEO environment on solar panels

    Allegri, G.; Corradi, S.; Marchetti, M.; Scaglione, S.

    2007-02-01

    The effects due to the LEO environment exposure of a solar array primary structure are here presented and discussed in detail. The synergistic damaging components featuring LEO environment are high vacuum, thermal cycling, neutral gas, ultraviolet (UV) radiation and cold plasma. The synergistic effects due to these environmental elements are simulated by "on ground" tests, performed in the Space Environment Simulator (SAS) at the University of Rome "La Sapienza"; numerical simulations are performed by the Space Environment Information System (SPENVIS), developed by the European Space Agency (ESA). A "safe life" design for a solar array primary structure is developed, taking into consideration the combined damaging action of the LEO environment components; therefore results from both numerical and experimental simulations are coupled within the framework of a standard finite element method (FEM) based design. The expected durability of the solar array primary structure, made of laminated sandwich composite, is evaluated assuming that the loads exerted on the structure itself are essentially dependent on thermo-elastic stresses. The optical degradation of surface materials and the stiffness and strength degradation of structural elements are taken into account to assess the global structural durability of the solar array under characteristic operative conditions in LEO environment.

  5. An FSI Simulation of the Metal Panel Deflection in a Shock Tube Using Illinois Rocstar Simulation Suite

    Shin, Jung Hun; Sa, Jeong Hwan; Kim, Han Gi; Cho, Keum Won [Korea Institute of Science and Technology Information, Daejeon (Korea, Republic of)

    2017-05-15

    As the recent development of computing architecture and application software technology, real world simulation, which is the ultimate destination of computer simulation, is emerging as a practical issue in several research sectors. In this paper, metal plate motion in a square shock tube for small time interval was calculated using a supercomputing-based fluid-structure-combustion multi-physics simulation tool called Illinois Rocstar, developed in a US national R and D program at the University of Illinois. Afterwards, the simulation results were compared with those from experiments. The coupled solvers for unsteady compressible fluid dynamics and for structural analysis were based on the finite volume structured grid system and the large deformation linear elastic model, respectively. In addition, a strong correlation between calculation and experiment was shown, probably because of the predictor corrector time-integration scheme framework. In the future, additional validation studies and code improvements for higher accuracy will be conducted to obtain a reliable open-source software research tool.

  6. Simulating cosmic radiation absorption and secondary particle production of solar panel layers of Low Earth Orbit (LEO) satellite with GEANT4

    Yiǧitoǧlu, Merve; Veske, Doǧa; Nilüfer Öztürk, Zeynep; Bilge Demirköz, Melahat

    2016-07-01

    All devices which operate in space are exposed to cosmic rays during their operation. The resulting radiation may cause fatal damages in the solid structure of devices and the amount of absorbed radiation dose and secondary particle production for each component should be calculated carefully before the production. Solar panels are semiconductor solid state devices and are very sensitive to radiation. Even a short term power cut-off may yield a total failure of the satellite. Even little doses of radiation can change the characteristics of solar cells. This deviation can be caused by rarer high energetic particles as well as the total ionizing dose from the abundant low energy particles. In this study, solar panels planned for a specific LEO satellite, IMECE, are analyzed layer by layer. The Space Environment Information System (SPENVIS) database and GEANT4 simulation software are used to simulate the layers of the panels. The results obtained from the simulation will be taken in account to determine the amount of radiation protection and resistance needed for the panels or to revise the design of the panels.

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

    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.

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

    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.

  9. Helium refrigerator for 'SULTAN'

    Arpagaus, M.; Erlach, H.; Quack, H.

    1984-01-01

    The authors describe the helium refrigerator designed for the SULTAN test facility. SULTAN (Supraleiter-Testanlage) is intended to serve for the developments and testing of high field superconducting magnets. These magnets are needed mainly for future applications in nuclear fusion. (Auth.)

  10. Helium dilution refrigerator

    1973-01-01

    A new system of continuous heat exchange for a helium dilution refrigerator is proposed. The 3 He effluent tube is concurrent with the affluent mixed helium tube in a vertical downward direction. Heat exchange efficiency is enhanced by placing in series a number of elements with an enlarged surface area

  11. SolarChill - a solar PV refrigerator without battery

    Pedersen, P.H.; Poulsen, S.; Katic, I. [Danish Technological Inst., Taastrup (Denmark)

    2004-07-01

    A solar powered refrigerator (SolarChill) has been developed in an international project involving Greenpeace International, GTZ, UNICEF, UNEP, WHO, industrial partners and Danish Technological Institute. The refrigerator is able to operate directly on solar PV panels, without battery or additional electronics, and is therefore suitable for locations where little maintenance and reliable operation is mandatory. The main objective of the SolarChill Project is to help deliver vaccines and refrigeration to the rural poor. To achieve this objective, the SolarChill Project developed - and plans to make freely available a versatile refrigeration technology that is environmentally sound, technologically reliable, and affordable. SolarChill does not use any fluorocarbons in its cooling system or in the insulation. For domestic and small business applications, another type of solar refrigerator is under development. This is an upright type, suitable for cool storage of food and beverages in areas where grid power is non-existent or unstable. The market potential for this type is thus present in industrialised countries as well as in countries under development. The unique feature of SolarChill is that energy is stored in ice instead of in batteries. An ice compartment keeps the cabinet at desired temperatures during the night. The paper describes the product development, possible SolarChill applications and experience with the two types of solar refrigerators, as well as results from the laboratory and field test. (orig.)

  12. Control Methods Utilizing Energy Optimizing Schemes in Refrigeration Systems

    Larsen, L.S; Thybo, C.; Stoustrup, Jakob

    2003-01-01

    The potential energy savings in refrigeration systems using energy optimal control has been proved to be substantial. This however requires an intelligent control that drives the refrigeration systems towards the energy optimal state. This paper proposes an approach for a control, which drives th...... the condenser pressure towards an optimal state. The objective of this is to present a feasible method that can be used for energy optimizing control. A simulation model of a simple refrigeration system will be used as basis for testing the control method....

  13. Displacer Diameter Effect in Displacer Pulse Tube Refrigerator

    Zhu, Shaowei

    2017-12-01

    Gas driving displacer pulse tube refrigerators are one of the work recovery type of pulse tube refrigerators whose theoretical efficiency is the same as Stirling refrigerators'. Its cooling power is from the displacement of the displacer. Displace diameter, rod diameter and pressure drop of the regenerator influence the displacement, which are investigated by numerical simulation. It is shown that the displacement ratio of the displacer over the piston is almost not affected by the displacer diameter at the same rod diameter ratio, or displacer with different diameters almost has the same performance.

  14. Experimental and Simulation for the Effect of Partial Shading on Solar Panel Performance

    Emad Talib Hahsim

    2016-06-01

    Full Text Available Partial shading is one of the problems that affects the power production and the efficiency of photovoltaic module. A series of experimental work have been done of partial shading of monocrystalline PV module; 50W, Isc: 3.1A, Voc: 22V with 36 cells in series is achieved. Non-linear power output responses of the module are observed by applying various cases of partial shading (vertical and horizontal shading of solar cells in the module. Shading a single cell (corner cell has the greatest impact on output energy. Horizontal shading or vertical shading reduced the power from 41W to 18W at constant solar radiation 1000W/m2 and steady state condition. Vertical blocking a column of cells (9 cells in a module reduces the power from 41W to 18W (53% power reduction; while, blocking one or two cell in the row reduces the power from 41 W to 18W (53% power reduction. Shading three or four cells in the same row reduces the power from 41W to 1W or 0.006W (94% power reduction. A complete Matlab / Simulink model are achieved to simulate the effect of partial shading on power output of module. It is found that shading a single cell reduces the power from 50 W to 25 W (50% using Matlab/Simulink model. Comparisons have been made between the I-V and P-V characteristic curves from the simulation with the practical (experimental curves. The results showed that the percentage of error between the Simulink results and the corresponding experimental measurement are 22% without shading effect and, 32% with partial shading.

  15. Numerical simulation and experimental results of horizontal tube falling film generator working in a NH3-LiNO3 absorption refrigeration system

    Herrera, J.V.; Garcia-Valladares, O.; Gomez, V.H.; Best, R.

    2010-01-01

    This paper describes the work made at the Centro de Investigacion en Energia in the development of an absorption refrigeration system for cooling and refrigeration applications with a capacity of 10 kW. The single effect unit utilizes ammonia-lithium nitrate as working pair and it is air cooled. The generator is a falling film type with horizontal tubes where the heating oil flows inside the tube bank and the ammonia-lithium nitrate solution flows as a falling film on the tube outside, where it is heated and ammonia vapor is generated. The generator consists of tree columns and four rows per column of horizontal tubes. The system was tested at controlled conditions with heating oil obtained from an electric resistance heating loop. A numerical model of the horizontal falling film generator was developed that divided the system into three different thermal elements: the flow inside the tube, the heat conduction in the tube wall and the falling film solution flow. The mathematical model was tested and validated with experimental data and a study of the influence of the heat transfer coefficient for ammonia-lithium nitrate solution in the numerical model was carried out. A comparison between experimental and numerical data for the heat flux in the system and the temperature profiles in the oil and solution flows shown a good degree of correlation.

  16. Development of a Battery-Free Solar Refrigerator

    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

  17. Superfluid thermodynamic cycle refrigerator

    Swift, Gregory W.; Kotsubo, Vincent Y.

    1992-01-01

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

  18. Flammability Indices for Refrigerants

    Kataoka, Osami

    This paper introduces a new index to classify flammable refrigerants. A question on flammability indices that ASHRAE employs arose from combustion test results of R152a and ammonia. Conventional methods of not only ASHRAE but also ISO and Japanese High-pressure gas safety law to classify the flammability of refrigerants are evaluated to show why these methods conflict with the test results. The key finding of this paper is that the ratio of stoichiometric concentration to LFL concentration (R factor) represents the test results most precisely. In addition, it has excellent correlation with other flammability parameters such as flame speed and pressure rise coefficient. Classification according to this index gives reasonable flammability order of substances including ammonia, R152a and carbon monoxide. Theoretical background why this index gives good correlation is also discussed as well as the insufficient part of this method.

  19. Three-dimensional self-consistent radiation transport model for the fluid simulation of plasma display panel cell

    Kim, H.C.; Yang, S.S.; Lee, J.K.

    2003-01-01

    In plasma display panels (PDPs), the resonance radiation trapping is one of the important processes. In order to incorporate this effect in a PDP cell, a three-dimensional radiation transport model is self-consistently coupled with a fluid simulation. This model is compared with the conventional trapping factor method in gas mixtures of neon and xenon. It shows the differences in the time evolutions of spatial profile and the total number of resonant excited states, especially in the afterglow. The generation rates of UV light are also compared for the two methods. The visible photon flux reaching the output window from the phosphor layers as well as the total UV photon flux arriving at the phosphor layer from the plasma region are calculated for resonant and nonresonant excited species. From these calculations, the time-averaged spatial profiles of the UV flux on the phosphor layers and the visible photon flux through the output window are obtained. Finally, the diagram of the energy efficiency and the contribution of each UV light are shown

  20. WIPP [Waste Isolation Pilot Plant] panel entryway seal: Numerical simulation of seal composite interaction for preliminary design evaluation

    Argueello, J.G.

    1988-04-01

    This report presents the results of a series of structural analyses performed to evaluate the structural interaction of the components of a potential two-component panel entryway seal configuration with each other and with the rock salt formation at the repository horizon of the Waste Isolation Pilot Plant. A two-dimensional axisymmetric geomechanical model is used to numerically simulate the interaction of the components of a 30.48 m (100 ft) long seal, consisting of concrete end caps and a crushed salt core, with each other and with the surrounding formation. Issues addressed in this report pertain to the consolidation of the crushed salt in terms of how much of the seal core reaches effective consolidation in the presence of the stiff concrete end caps since these could conceivably cause bridging (retardation of closure around the core) to occur. In addition, the stress field in the end caps is evaluated to determine if the concrete component maintains its integrity. The stresses induced in the surrounding formation are also evaluated to determine if the presence of the concrete component in the seal system results in a ''tightening'' of the formation around the seal. 20 refs., 43 figs., 2 tabs

  1. Quantum-Circuit Refrigerator

    MöTtöNen, Mikko; Tan, Kuan Y.; Masuda, Shumpei; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Silveri, Matti; Grabert, Hermann

    Quantum technology holds great potential in providing revolutionizing practical applications. However, fast and precise cooling of the functional quantum degrees of freedom on demand remains a major challenge in many solid-state implementations, such as superconducting circuits. We demonstrate direct cooling of a superconducting resonator mode using voltage-controllable quantum tunneling of electrons in a nanoscale refrigerator. In our first experiments on this type of a quantum-circuit refrigerator, we measure the drop in the mode temperature by electron thermometry at a resistor which is coupled to the resonator mode through ohmic losses. To eliminate unwanted dissipation, we remove the probe resistor and directly observe the power spectrum of the resonator output in agreement with the so-called P(E) theory. We also demonstrate in microwave reflection experiments that the internal quality factor of the resonator can be tuned by orders of magnitude. In the future, our refrigerator can be integrated with different quantum electric devices, potentially enhancing their performance. For example, it may prove useful in the initialization of superconducting quantum bits and in dissipation-assisted quantum annealing. We acknowledge European Research Council Grant SINGLEOUT (278117) and QUESS (681311) for funding.

  2. THERMODYNAMIC PROPERTIES OF SELECTED HFC REFRIGERANTS

    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...

  3. Thermal investigations of a room temperature magnetic refrigerator

    Smaili, Arezki; Chiba, Younes [Ecole Nationale Polytechnique d' Alger (Algeria)], email: arezki.smaili@enp.edu.dz

    2011-07-01

    Magnetic refrigeration is a concept based on the magnetocaloric effect that some materials exhibit when the external magnetic field changes. The aim of this paper is to assess the performance of a numerical model in predicting parameters of an active magnetic regenerator refrigerator. Numerical simulations were conducted to perform a thermal analysis on an active magnetic regenerator refrigerator operating near room temperature with and without applied cooling load. Curves of temperature span, cooling capacity and thermal efficiency as functions of the operating conditions were drawn and are presented in this paper. Results showed that at fixed frequency Ql versus mf has an optimum and COP was increased with cycle frequency values. This study demonstrated that the proposed numerical model could be used to predict parameters of an active magnetic regenerator refrigerator as it provides consistent results.

  4. Performance evaluation of integrated trigeneration and CO2 refrigeration systems

    Suamir, IN.; Tassou, S.A.

    2013-01-01

    Food retailing is one of the most energy intensive sectors of the food cold chain. Its environmental impacts are significant not only because of the indirect effect from CO 2 emissions at the power stations but also due to the direct effect arising from refrigerant leakage to the atmosphere. The overall energy efficiency of supermarkets can be increased by integrating the operation of CO 2 refrigeration and trigeneration systems. This paper compares three alternative schemes in a medium size supermarket. Experimental results and simulation studies have shown that the best scheme for energy and GHG emissions savings is the one where the cooling produced by the trigeneration system is used to condense the CO 2 fluid in the refrigeration system to ensure subcritical operation throughout the year. It is shown that this system can produce 30% energy savings and over 40% greenhouse gas emissions savings over conventional refrigeration and indoor environment control systems in supermarkets.

  5. Theoretical research on the performance of the transcritical ejector refrigeration cycle with various refrigerants

    Wang, F.; Li, D.Y.; Zhou, Y.

    2015-01-01

    The transcritical ejector refrigeration cycle (TERC), which has shown an attractive alternative to the ejector refrigeration systems, can better match large variable-temperature heat sources and yields higher COP. In this paper, in order to find a proper working fluid for the TERC, the performance of the TERC with CO_2 and various working fluids with low critical temperatures including R1270, R32, R143a, R125 and R115 are studied and compared. A thermodynamic model for ejector is set up to simulate the ejector by introducing the real properties of refrigerants. The results indicate that R1270 has the highest COP at the same heat source condition and medium working pressures, and is one of environment-friendly working fluids, hence R1270 is the most proper one. The COP of the transcritical cycle is higher than that of the subcritical cycle, and The effective performance coefficient COP_m of the transcritical cycle is also better. When the heater outlet temperature is increased, its system COP_m improves, but its system COP almost does not change. - Highlights: • A thermodynamic model is used to simulate the ejector with real properties. • The performance of the TERC with various refrigerants is compared. • The environment-friendly working fluid of R1270 shows the most proper one. • The COP of the transcritical cycle is higher than that of the subcritical cycle.

  6. Effect of evaporator temperature on vapor compression refrigeration system

    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.

  7. Fermilab tevatron five refrigerator system tests

    Rode, C.; Ferry, R.; Leiniger, M.; Makara, J.; Misek, J.; Mizicko, D.; Richied, D.; Theilacker, J.

    1982-01-01

    The Fermilab Tevatron refrigeration system is described with the layout illustrated. The compressor control loops, the refrigerator control loops, and magnet control loops (two per refrigerator) are described and each illustrated. The mobile purifier is described. A five refrigerator test is presented, using two compressor buildings, satellite refrigerator concept test and the test current to the writing. The configuration of the five refrigerator test is diagramed

  8. Helium refrigeration system for hydrogen liquefaction applications

    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.

  9. Energy optimisation of domestic refrigerators

    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 ...

  10. Thermodynamic analysis of hydrocarbon refrigerants in a sub-cooling refrigeration system

    BUKOLA O. BOLAJI

    2013-06-01

    Full Text Available In this study, the performance simulation of some hydrocarbon refrigerants (R290, R600 and R600a as alternatives to R134a in refrigeration system with sub-cooling is conducted by thermodynamic calculation of performance parameters using the REFPROP software. The results obtained showed that the saturated vapour pressure and temperature characteristic profiles for R600 and R600a are very close to that of R134a. The three hydrocarbon refrigerants exhibited very high refrigerating effect and condenser duty than R134a. The best of these parameters was obtained using R600. The discharge temperatures obtained using R600 and R600a were low, while that of R290 was very much higher. The highest coefficient of performance (COP and relative capacity index were obtained using R600. Average COPs of R600 and R600a are 4.6 and 2.2% higher than that of R134a, respectively. The performances of R600 and R600a in system were better than those of R134a and R290. The best performance was obtained using R600 in the system.

  11. Dynamic model of an autonomous solar absorption refrigerator

    Ali Fellah; Tahar Khir; Ammar Ben Brahim

    2009-01-01

    The performance analysis of a solar absorption refrigerator operating in an autonomous way is investigated. The water/LiBr machine satisfies the air-conditioning needs along the day. The refrigerator performances were simulated regarding a dynamic model. For the solar driven absorption machines, two applications could be distinguished. The sun provides the thermal part of the useful energy. In this case, it is necessary to use additional energy as the electric one to activate the pumps, the fans and the control system. On the other hand, the sun provides all the necessary energy. Here, both photovoltaic cells and thermal concentrators should be used. The simulation in dynamic regime of the cycle requires the knowledge of the geometric characteristics of every component as the exchange areas and the internal volumes. Real characteristics of a refrigerator available at the applied thermodynamic research unit (ATRU) at the engineers' national school of Gabes are notified. The development of the thermal and matter balances in every component of the cycle has permitted to simulate in dynamic regime the performances of a solar absorption refrigerator operating with the water/LiBr couple for air-conditioning needs. The developed model could be used to perform intermittent refrigeration cycle autonomously driven. (author)

  12. Panel Analysis

    Brænder, Morten; Andersen, Lotte Bøgh

    2014-01-01

    Based on our 2013-article, ”Does Deployment to War Affect Soldiers' Public Service Motivation – A Panel Study of Soldiers Before and After their Service in Afghanistan”, we present Panel Analysis as a methodological discipline. Panels consist of multiple units of analysis, observed at two or more...... in research settings where it is not possible to distribute units of analysis randomly or where the independent variables cannot be manipulated. The greatest disadvantage in regard to using panel studies is that data may be difficult to obtain. This is most clearly vivid in regard to the use of panel surveys...... points in time. In comparison with traditional cross-sectional studies, the advantage of using panel studies is that the time dimension enables us to study effects. Whereas experimental designs may have a clear advantage in regard to causal inference, the strength of panel studies is difficult to match...

  13. Potential energy savings using dynamically optimizing control in refrigeration systems under daily variations in ambient temperature

    Larsen, Lars Finn Sloth; Thybo, Claus; Wisniewski, Rafal

    2007-01-01

    The objective of this study is to investigate the energy saving potential for refrigeration systems by refrigeration more at the colder night time than at the warmer day time. The potential is evaluated using an optimal control policy and illustrated on a simulation example. The results show...

  14. Performance of an auto refrigerant cascade refrigerator operating in gas refrigerant supply (GRS) mode with nitrogen-hydrocarbon and argon-hydrocarbon refrigerants

    Gurudath Nayak, H.; Venkatarathnam, G.

    2009-07-01

    There is a worldwide interest in the development of auto refrigerant cascade (ARC) refrigerators operating with refrigerant mixtures. Both flammable and non-flammable refrigerant mixtures can be used in these systems. The performance of an ARC system with optimum nitrogen-hydrocarbon and argon-hydrocarbon mixtures between 90 and 160 K is presented in this paper.

  15. 基于面元法的水平轴风力机数值模拟%Numerical Simulation of Horizontal Axis Wind Turbine Based on Panel Method

    仇永兴; 康顺

    2012-01-01

    使用基于速度面元法的势流数值模拟方法,以NREL Phase VI为例进行了叶片气动载荷和风轮近尾流场的数值模拟。将势流数值模拟、叶素动量理论和计算流体力学CFD方法的计算结果与实验数据进行了对比分析。结果表明使用速度面元法计算风轮绕流场具有较高的计算精度和求解效率,为大规模风力机群的流场计算和出力预报提供支撑。%The aerodynamic loads and the near-wake flow fields of a wind turbine, NREL Phase VI, are simulated by numerical simulations using the velocity based panel method. The results of numerical simulations of potential flows are analyzed and compared with that of blade element momentum theory, computational fluid dynamics (CFD) and experimental data. It is shown that the velocity based panel method is more precise and efficient for the aerodynamic simulations of the wind turbine. The conclusions can be used as technical supports for the flow field calculation and the performance prediction of wind turbine groups.

  16. Dilution Refrigeration of Multi-Ton Cold Masses

    Wikus, P; CERN. Geneva

    2007-01-01

    Dilution refrigeration is the only means to provide continuous cooling at temperatures below 250 mK. Future experiments featuring multi-ton cold masses require a new generation of dilution refrigeration systems, capable of providing a heat sink below 10 mK at cooling powers which exceed the performance of present systems considerably. This thesis presents some advances towards dilution refrigeration of multi-ton masses in this temperature range. A new method using numerical simulation to predict the cooling power of a dilution refrigerator of a given design has been developed in the framework of this thesis project. This method does not only allow to take into account the differences between an actual and an ideal continuous heat exchanger, but also to quantify the impact of an additional heat load on an intermediate section of the dilute stream. In addition, transient behavior can be simulated. The numerical model has been experimentally verified with a dilution refrigeration system which has been designed, ...

  17. Thermoacoustic refrigerator for space applications

    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.

  18. Magnetic refrigeration apparatus and method

    Barclay, John A.; Overton, Jr., William C.; Stewart, Walter F.

    1984-01-01

    The disclosure relates to refrigeration through magnetizing and demagnitizing a body by rotating it within a magnetic field. Internal and external heat exchange fluids and in one embodiment, a regenerator, are used.

  19. ENERGY STAR Certified Residential Refrigerators

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 5.0 ENERGY STAR Program Requirements for Residential Refrigerators and Freezers that are...

  20. Performance of refrigerating machineries with new refrigerants; Performance des machines frigorifiques avec les nouveaux refrigerants

    Bailly, A; Jurkowski, R [CIAT, 01 - Culoz (France)

    1998-12-31

    This paper reports on a comparative study of the thermal performances of different refrigerants like R-22, R-134a, R-404A and R-407C when used as possible substitutes for the HCFC22 refrigerant in a given refrigerating machinery equipped with compact high performance plate exchangers. Thermal performances are compared in identical operating conditions. The behaviour of the two-phase exchange coefficient is analyzed with respect to the different parameters. The composition of the mixture after one year of operation has been analyzed too and the influence of oil on the performances is studied. (J.S.)

  1. Performance of refrigerating machineries with new refrigerants; Performance des machines frigorifiques avec les nouveaux refrigerants

    Bailly, A.; Jurkowski, R. [CIAT, 01 - Culoz (France)

    1997-12-31

    This paper reports on a comparative study of the thermal performances of different refrigerants like R-22, R-134a, R-404A and R-407C when used as possible substitutes for the HCFC22 refrigerant in a given refrigerating machinery equipped with compact high performance plate exchangers. Thermal performances are compared in identical operating conditions. The behaviour of the two-phase exchange coefficient is analyzed with respect to the different parameters. The composition of the mixture after one year of operation has been analyzed too and the influence of oil on the performances is studied. (J.S.)

  2. Refrigeration plants for the SSCL

    McAshan, M.; Ganni, V.; Than, R.; Niehaus, T.

    1991-03-01

    The basic requirements and operating features of the collider cryogenic system have already been described in other publications. The general arrangement of the refrigeration plant and its subsystems is presented, and the issue of how to provide redundancy in the cryogenic system is addressed, and some of the basic features of the refrigeration plants are described. The collider cryogenic system design is not final yet, and this report only reflects the direction and current status of the cryogenic system design

  3. Superefficient Refrigerators: Opportunities and Challenges for Efficiency Improvement Globally

    Shah, Nihar; Park, Won Young; Bojda, Nicholas; McNeil, Michael A.

    2014-08-01

    As an energy-intensive mainstream product, residential refrigerators present a significant opportunity to reduce electricity consumption through energy efficiency improvements. Refrigerators expend a considerable amount of electricity during normal use, typically consuming between 100 to 1,000 kWh of electricity per annum. This paper presents the results of a technical analysis done for refrigerators in support of the Super-efficient Equipment and Appliance Deployment (SEAD) initiative. Beginning from a base case representative of the average unit sold in India, we analyze efficiency improvement options and their corresponding costs to build a cost-versus-efficiency relationship. We then consider design improvement options that are known to be the most cost effective and that can improve efficiency given current design configurations. We also analyze and present additional super-efficient options, such as vacuum-insulated panels. We estimate the cost of conserved electricity for the various options, allowing flexible program design for market transformation programs toward higher efficiency. We estimate ~;;160TWh/year of energy savings are cost effective in 2030, indicating significant potential for efficiency improvement in refrigerators in SEAD economies and China.

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

    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.......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...... their Curie temperature. Simulations are implemented to investigate how to layer the FOPT materials for obtaining higher cooling capacity. Moreover, based on entropy generation minimization, optimization of the regenerator geometry and related operating parameters is presented for improving the AMR efficiency...

  5. Night Wind - Deliverable D.3.2 main simulation report; Grid architecture for wind power production with energy storage through load shifting in refrigerated warehouses

    Cronin, Tom; Bindner, Henrik; Zong, Yi

    2008-11-15

    This report represents Deliverable D.3.2 of Work Package 3 in the Night Wind project. The aim of this Work Package was to simulate a cold store (or number of cold stores) within a power system where there is a high degree of wind power penetration. The Night Wind Control System, developed as part of Work Package 5, was to be integrated into the simulations so that the wind power could be 'stored' in the cold store with maximum benefit to the electrical network, utility or cold store owner. To this end, the following have been accomplished: 1) The Night Wind concept has been described in terms of demand side management. 2) Input requirements and data have been specified and collected. Measured data from the existing cold store facility of Partner Logistics has been analysed. 3) Component models for the simulations (including the cold store model itself) have been developed for the simulation platform, IPSYS. 4) The Night Wind Control System (NWCS) from Work Package 5 has been developed so that it finishes computations within two minutes. 5) Controllers including the NWCS) have been operated with the cold store model within IPSYS. 6) Simulations have been performed with the cold store model and an increasing penetration of wind power. This report presents the results of the work undertaken in Work Package 3 which would have benefited from the additional time requested at the project meeting in March 2008, however, this extension of time was not granted. Nevertheless, the work that was possible is considered significantly complete, although it is acknowledged that there has been a delay in the presentation of this report. It should be noted that it was not possible to address the new aspects of Task 3.7 'Verification of simulation results' as there was no implementation of the night wind concept at the demonstration site (Task 7). Verification of the simulation of the present system has, naturally, been carried out and described in this report. (ln)

  6. Demonstration of the Use of Remote Temperature Monitoring Devices in Vaccine Refrigerators in Haiti.

    Cavallaro, Kathleen F; Francois, Jeannot; Jacques, Roody; Mentor, Derline; Yalcouye, Idrissa; Wilkins, Karen; Mueller, Nathan; Turner, Rebecca; Wallace, Aaron; Tohme, Rania A

    After the 2010 earthquake, Haiti committed to introducing 4 new antigens into its routine immunization schedule, which required improving its cold chain (ie, temperature-controlled supply chain) and increasing vaccine storage capacity by installing new refrigerators. We tested the feasibility of using remote temperature monitoring devices (RTMDs) in Haiti in a sample of vaccine refrigerators fueled by solar panels, propane gas, or electricity. We analyzed data from 16 RTMDs monitoring 24 refrigerators in 15 sites from March through August 2014. Although 5 of the 16 RTMDs exhibited intermittent data gaps, we identified typical temperature patterns consistent with refrigerator door opening and closing, propane depletion, thermostat insufficiency, and overstocking. Actual start-up, annual maintenance, and annual electricity costs for using RTMDs were $686, $179, and $9 per refrigerator, respectively. In Haiti, RTMD use was feasible. RTMDs could be prioritized for use with existing refrigerators with high volumes of vaccines and new refrigerators to certify their functionality before use. Vaccine vial monitors could provide additional useful information about cumulative heat exposure and possible vaccine denaturation.

  7. Acoustic field characteristics and performance analysis of a looped travelling-wave thermoacoustic refrigerator

    Jin, T.; Yang, R.; Wang, Y.; Feng, Y.; Tang, K.

    2016-01-01

    Highlights: • Key issues for a highly efficient thermoacoustic conversion are analyzed. • A looped thermoacoustic refrigerator with one engine stage and one refrigerator stage is proposed. • Effective refrigeration powered by heat sources below 250 °C is demonstrated in the simulation. • Impact of cooling/heating temperatures on system performance is analyzed in view of acoustic field. - Abstract: This paper focuses on a looped travelling-wave thermoacoustic refrigerator powered by thermal energy. Based on a simplified model for the regenerator, key issues for a highly efficient thermoacoustic conversion, including both thermal-to-acoustic and heat-pumping processes, are summarized. A looped travelling-wave thermoacoustic refrigerator with one engine stage and one refrigerator stage is proposed, with emphasis on high normalized acoustic impedance, sufficient volumetric velocity and appropriate phase relation close to travelling wave in the regenerators of both engine and refrigerator. Simulation results indicate that for the ambient temperature of 30 °C, the looped travelling-wave thermoacoustic refrigerator can be powered by the heat at 210–250 °C to achieve the refrigeration at −3 °C with the overall coefficient of performance above 0.4 and the relative Carnot coefficient of performance over 13%. The characteristics of the acoustic field inside the loop configuration are analyzed in detail to reveal the operation mechanism of the looped travelling-wave thermoacoustic refrigerator. Additional analyses are conducted on the impact of the cooling and the heating temperatures, which are of great concern to the refrigeration applications and the utilization of low-grade thermal energy.

  8. Refrigeration waste heat recovery

    1983-03-01

    UK Super A Stores was built in 1972 and is part of a small indoor shopping complex linked together by a heated mall. The store has a public floor area of approximately 1,232 m{sup 2} (13,261 ft.{sup 2}) and sells the usual variety of food produce including a large selection of frozen foods. There are five lengths of refrigerated display cabinets with a total area of approximately 78 m{sup 2}. There are also some frozen food storage rooms at the back of the store. This report provides a description of a waste heat recovery system within a medium sized food store. It details how the waste heat that is produced by the conventional frozen food display cabinets, can be reused by the store's space heating system. Recommended uses for this waste heat include: diverting to the loading bays which would make the reheat coil unnecessary, diverting to the front of the shop, and heating the adjacent shopping mall. The CREDA (Conservation and Renewable Energy Demonstration Assistance) program contributed $17,444 towards the total project cost of $30,444. The project was initiated by the store owner, who is now realizing a lower annual fuel consumption, with the resulting financial savings. 11 figs., 1 tab.

  9. 76 FR 23298 - Bottom Mount Combination Refrigerator-Freezers From the Republic of Korea: Initiation of...

    2011-04-26

    ... like product as ``a product which is like, or in the absence of like, most similar in characteristics... refrigeration using compression technology, with all of the following characteristics: The cabinet contains at... a minimum: (a) an external metal shell, (b) a back panel, (c) a deck, (d) an interior plastic liner...

  10. Limited options for low-global-warming-potential refrigerants

    McLinden, Mark O.; Brown, J. Steven; Brignoli, Riccardo; Kazakov, Andrei F.; Domanski, Piotr A.

    2017-02-01

    Hydrofluorocarbons, currently used as refrigerants in air-conditioning systems, are potent greenhouse gases, and their contribution to climate change is projected to increase. Future use of the hydrofluorocarbons will be phased down and, thus replacement fluids must be found. Here we show that only a few pure fluids possess the combination of chemical, environmental, thermodynamic, and safety properties necessary for a refrigerant and that these fluids are at least slightly flammable. We search for replacements by applying screening criteria to a comprehensive chemical database. For the fluids passing the thermodynamic and environmental screens (critical temperature and global warming potential), we simulate performance in small air-conditioning systems, including optimization of the heat exchangers. We show that the efficiency-versus-capacity trade-off that exists in an ideal analysis disappears when a more realistic system is considered. The maximum efficiency occurs at a relatively high volumetric refrigeration capacity, but there are few fluids in this range.

  11. Experimental and numerical results of a high frequency rotating active magnetic refrigerator

    Lozano, Jaime; Engelbrecht, Kurt; Bahl, Christian

    2012-01-01

    Experimental results for a recently developed prototype magnetic refrigeration device at The Technical University of Denmark (DTU) were obtained and compared with numerical simulation results. A continuously rotating active magnetic regenerator (AMR) using 2.8 kg packed sphere regenerators...

  12. Experimental and numerical results of a high frequency rotating active magnetic refrigerator

    Lozano, Jaime; Engelbrecht, Kurt; Bahl, Christian R.H.

    2014-01-01

    Experimental results for a recently developed prototype magnetic refrigeration device at the Technical University of Denmark (DTU) were obtained and compared with numerical simulation results. A continuously rotating active magnetic regenerator (AMR) using 2.8 kg packed sphere regenerators...

  13. Panel Session

    Bertelsen, Olav Wedege

    2004-01-01

    In this panel session, four researchers will discuss the role of a theoretical foundation, in particular AT, in the design of information technology based artefacts. The general discussion will take of from a specific examination of the ActAD approach.......In this panel session, four researchers will discuss the role of a theoretical foundation, in particular AT, in the design of information technology based artefacts. The general discussion will take of from a specific examination of the ActAD approach....

  14. Refrigeration Performance and Entropy Generation Analysis for Reciprocating Magnetic Refrigerator with Gd Plates

    Yonghua You

    2018-06-01

    Full Text Available In the current work, a novel 2D numerical model of stationary grids was developed for reciprocating magnetic refrigerators, with Gd plates, in which the magneto-caloric properties, derived from the Weiss molecular field theory, were adopted for the built-in energy source of the magneto-caloric effect. The numerical simulation was conducted under the conditions of different structural and operational parameters, and the effects of the relative fluid displacement (φ on the specific refrigeration capacity (qref and the Coefficient of Performance (COP were obtained. Besides the variations of entropy, the generation rate and number were studied and the contours of the local entropy generation rate are presented for discussion. From the current work, it is found that with an increase in φ, both the qref and COP followed the convex variation trend, while the entropy generation number (Ns varied concavely. As for the current cases, the maximal qref and COP were equal to 151.2 kW/m3 and 9.11, respectively, while the lowest Ns was the value of 2.4 × 10−4 K−1. However, the optimal φ for the largest qref and COP, and for the lowest Ns, were inconsistent, thus, some compromises need be made in the optimization of magnetic refrigerators.

  15. Performance analysis of the reciprocating compressor with hydrocarbon refrigerant mixtures, R290/R600a

    Kim, J.H.; Chung, Y.G.; Pak, H.Y. [Hanyang University, Seoul (Korea); Park, K.W. [LG Industrial Systems, Seoul (Korea)

    1999-03-01

    A performance analysis simulation program that can be applied to a hermetic reciprocating compressor with various refrigerants has been developed. For the numerical analysis, the passage of refrigerant in compressor is subdivided into control volumes. Instead of the ideal gas assumption, CSD equation of state is applied to calculate the thermodynamic properties of refrigerants. To verify the validity of developed program, the result has been compared with the experimental data served by the compressor supplier. The performance of each refrigerant and the possibility of direct application are estimated by applying R12, 134a, R290, R600a and R290/R600a mixture to an existing compressor. Also, parametric study for various crank rotating speeds and the mole fractions of refrigerant has been performed. 22 refs., 12 figs., 5 tabs.

  16. An improved wave rotor refrigerator using an outside gas flow for recycling the expansion work

    Zhao, J.; Hu, D.

    2017-03-01

    To overcome the bottleneck of traditional gas wave refrigeration, an improved wave rotor refrigerator (WRR) cycle has been proposed, in which the expansion work was recycled during the process of refrigeration. Thermodynamic analysis of the two cycles shows that the refrigeration efficiency of the improved WRR cycle has been greatly increased compared with the traditional WRR. The performance of an improved WRR was investigated by adjusting the major operational parameters, such as the rotational speed of the wave rotor, port size, and inflow overpressure. The experimental results show that pressure loss can be reduced by nearly 40 % in this improved refrigeration system. Meanwhile, a two-dimensional numerical simulation was performed to understand the wave interactions that take place inside the rotor channels.

  17. Krypton based adsorption type cryogenic refrigerator

    Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

    1989-01-01

    Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

  18. REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    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, ...

  19. Thermoelectric refrigerator having improved temperature stabilization means

    Falco, C.M.

    1982-01-01

    A control system for thermoelectric refrigerators is disclosed. The thermoelectric refrigerator includes at least one thermoelectric element that undergoes a first order change at a predetermined critical temperature. The element functions as a thermoelectric refrigerator element above the critical temperature, but discontinuously ceases to function as a thermoelectric refrigerator element below the critical temperature. One example of such an arrangement includes thermoelectric refrigerator elements which are superconductors. The transition temperature of one of the superconductor elements is selected as the temperature control point of the refrigerator. When the refrigerator attempts to cool below the point, the metals become superconductors losing their ability to perform as a thermoelectric refrigerator. An extremely accurate, first-order control is realized

  20. Anti-synchronizing control for supermarket refrigeration systems

    Larsen, Lars Finn Sloth; Thybo, Claus; Wisniewski, Rafal

    2007-01-01

    Abstract—A supermarket refrigeration system is a hybrid system with switched nonlinear dynamics and discrete-valued input variables such as opening/closing of valves and start/stop of compressors. Practical and simulation studies have shown that the use of distributed hysteresis controllers...... schemes of low complexity for desynchronizing the valve operations while improving performance. Simulation results indicate the potential increase in efficiency and reduction in wear comparing with traditional control schemes....

  1. Synchronization and Desynchronizing Control Schemes for Supermarket Refrigeration Systems

    Larsen, Lars Finn Sloth; Thybo, Claus Thybo; Izadi-Zamanabadi, Roozbeh

    2007-01-01

    A supermarket refrigeration system is a hybrid system with switched nonlinear dynamics and discrete-valued input variables such as opening/closing of valves and start/stop of compressors. Practical and simulation studies have shown that the use of distributed hysteresis controllers to operate...... complexity for desynchronizing the valve operations while improving performance. Simulation results indicate the potential increase in efficiency and reduction in wear comparing with traditional control schemes....

  2. Load forecasting for supermarket refrigeration

    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...

  3. Control optimizations for heat recovery from CO2 refrigeration systems in supermarket

    Ge, Y.T.; Tassou, S.A.

    2014-01-01

    Highlights: • Application of supermarket energy control system model. • Heat recovery from CO 2 refrigeration system in supermarket space conditioning. • Effect of pressure controls of CO 2 refrigeration system on heat recovery potentials. • Control optimization of CO 2 refrigeration system for heat recovery in supermarket. - Abstract: A modern supermarket energy control system has a concurrent need for electricity, food refrigeration and space heating or cooling. Approximately 10% of this energy is for conventional gas-powered heating. In recent years, the use of CO 2 as a refrigerant in supermarket systems has received considerable attention due to its negligible contribution to direct greenhouse gas emissions and excellent thermophysical and heat transfer properties. CO 2 refrigeration systems also offer more compact component designs over a conventional HFC system and heat recovery potential from compressor discharge. In this paper, the heat recovery potential of an all-CO 2 cascade refrigeration system in a supermarket has been investigated using the supermarket simulation model “SuperSim” developed by the authors. It has been shown that at UK weather conditions, the heat recovery potential of CO 2 refrigeration systems can be increased by increasing the condenser/gas cooler pressure to the point where all the heat requirements are satisfied. However, the optimum level of heat recovery will vary during the year and the control system should be able to continuously optimize this level based on the relative cost of energy, i.e., gas and electricity

  4. 46 CFR 154.702 - Refrigerated carriage.

    2010-10-01

    ... Pressure and Temperature Control § 154.702 Refrigerated carriage. (a) Each refrigeration system must: (1) Have enough capacity to maintain the cargo vapor pressure in each cargo tank served by the system below... the purpose of this section, a “refrigeration unit” includes a compressor and its motors and controls...

  5. 49 CFR 173.174 - Refrigerating machines.

    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...

  6. Solar Refrigerators Store Life-Saving Vaccines

    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.

  7. Experimental and simulation of split semi-torus key in PVC foam core to improve the debonding resistance of composite sandwich panel

    Juliyana, M.; Santhana Krishnan, R.

    2018-02-01

    The sandwich composite panels consisting of facesheet and core material are used as a primary structural member for aerospace, civil and marine areas due to its high stiffness to weight ratio. But the debonding nature of facesheet from the foam core under shear loading conditions leads to failure of the composite structure. To inhibit the debonding, an innovative methodology of introducing semi-torus key is used in the present study. The polyvinyl chloride foam core(PVC) is grooved and filled with semi-torus shaped chopped strand prepregs which are sandwiched between alternate layers of woven roven(WR) and chopped strand mat(CSM) skins by vacuum infusion process. The sandwich panel manufactured with semi-torus keys is evaluated regarding experimental and numerical simulations under shear loading conditions. The present innovative concept delays the debonding between face-sheet and foam core with enhancement the shear load carrying capability as the initial stiffness is higher than the conventional model. Also, the shear behaviour of the proposed concept is in good agreement with experimental results. The split semi-torus keys sustain the shear failure resulting in resistance to debonding capability.

  8. High Efficiency, Low Emission Refrigeration System

    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

  9. Modelling and control of large cryogenic refrigerator

    Bonne, Francois

    2014-01-01

    This manuscript is concern with both the modeling and the derivation of control schemes for large cryogenic refrigerators. The particular case of those which are submitted to highly variable pulsed heat load is studied. A model of each object that normally compose a large cryo-refrigerator is proposed. The methodology to gather objects model into the model of a subsystem is presented. The manuscript also shows how to obtain a linear equivalent model of the subsystem. Based on the derived models, advances control scheme are proposed. Precisely, a linear quadratic controller for warm compression station working with both two and three pressures state is derived, and a predictive constrained one for the cold-box is obtained. The particularity of those control schemes is that they fit the computing and data storage capabilities of Programmable Logic Controllers (PLC) with are well used in industry. The open loop model prediction capability is assessed using experimental data. Developed control schemes are validated in simulation and experimentally on the 400W1.8K SBT's cryogenic test facility and on the CERN's LHC warm compression station. (author) [fr

  10. Qubit absorption refrigerator at strong coupling

    Mu, Anqi; Agarwalla, Bijay Kumar; Schaller, Gernot; Segal, Dvira

    2017-12-01

    We demonstrate that a quantum absorption refrigerator (QAR) can be realized from the smallest quantum system, a qubit, by coupling it in a non-additive (strong) manner to three heat baths. This function is un-attainable for the qubit model under the weak system-bath coupling limit, when the dissipation is additive. In an optimal design, the reservoirs are engineered and characterized by a single frequency component. We then obtain closed expressions for the cooling window and refrigeration efficiency, as well as bounds for the maximal cooling efficiency and the efficiency at maximal power. Our results agree with macroscopic designs and with three-level models for QARs, which are based on the weak system-bath coupling assumption. Beyond the optimal limit, we show with analytical calculations and numerical simulations that the cooling efficiency varies in a non-universal manner with model parameters. Our work demonstrates that strongly-coupled quantum machines can exhibit function that is un-attainable under the weak system-bath coupling assumption.

  11. Design of an ejector cycle refrigeration system

    Grazzini, G.; Milazzo, A.; Paganini, D.

    2012-01-01

    Highlights: ► A design procedure is presented for an ejection refrigeration system. ► Properties of applicable operating fluids are presented and R245fa is selected. ► Real gas properties are used. ► The diffuser is designed with a profile that controls momentum change. ► Fluid friction is accounted for along all main components. - Abstract: A design procedure, based on a one-dimensional simulation, is presented for an ejection refrigeration system. Heat exchangers are included in the calculation, accounting for temperature differences between the fluids and for pressure losses. The ideal gas assumption, which is quite common in the literature concerning ejector systems, is avoided. Furthermore, the supersonic diffuser is designed with a continuous profile, without cylindrical piece, controlling the variation of momentum along the flow path and accounting for friction. At design conditions, this should reduce the irreversibility due to the normal shock. A comparison between different operating fluids is presented and R245fa is selected. The results of the design procedure and the expected performance, in terms of first and second law efficiency, are presented.

  12. Stability of split Stirling refrigerators

    Waele, de A.T.A.M.; Liang, W.

    2009-01-01

    In many thermal systems spontaneous mechanical oscillations are generated under the influence of large temperature gradients. Well-known examples are Taconis oscillations in liquid-helium cryostats and oscillations in thermoacoustic systems. In split Stirling refrigerators the compressor and the

  13. Control of the Tevatron Satellite Refrigeration system

    Theilacker, J.; Chapman, L.; Gannon, J.; Hentges, M.; Martin, M.; Rode, C.H.; Zagel, J.

    1984-01-01

    This chapter describes a computerized control system for 24 satellite refrigerators which cool a six kilometer ring of superconducting magnets. The control system consists of 31 independent microprocessors operating over 400 servo loops, and a central computer system which provides monitoring, alarms, logging and changing of parameters. Topics considered include pressure measurement, flow measurement, temperature measurement, gas analysis, control valves, expansion engine controllers, and control loops. Each refrigerator has 12 active microprocessor based control loops which tune the refrigerator to one of its four operating modes: satellite, liquefier, refrigerator, and stand-by. It is suggested that optimizing the refrigerator control loops and quench recovery scheme will minimize the accelerator down time

  14. Efficiency improvement of commercial refrigeration systems

    Denecke, Julius [NTNU, Trondheim (Norway); Hafner, Armin [SINTEF Energy Research, Trondheim (Norway)

    2011-07-01

    This work presents a historical review of carbon dioxide refrigeration systems. Further a literature survey is carried out to get a status of existing refrigeration technology related to supermarkets. In the next step various energy saving options are stated. A heat recovery model, basing on a R744 booster refrigeration system is established and described. Simplified demand curves for refrigeration, air conditioning and heating will base this model to calculate different heat recovery layouts. Supermarket future trends will be considered and integrated in the calculation. Finally the calculated energy consumptions will be compared with real energy consumptions of selected supermarket refrigeration systems.

  15. Overall performance of the duplex Stirling refrigerator

    Erbay, L. Berrin; Ozturk, M. Mete; Doğan, Bahadır

    2017-01-01

    Highlights: • Overall performance coefficient of duplex Stirling refrigerator was investigated. • A definite region for the coefficient of performance of the refrigerator in duplex Stirling is identified. • A definite region for the thermal efficiency of the heat engine in duplex Stirling is identified. • Benchmark values and design bounds of the duplex Stirling refrigerator were obtained. - Abstract: The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine and Stirling cycle refrigerator used for cooling. The equality of the work generation of the heat engine to the work consumption of the refrigerator is the primary constraint of the duplex Stirling. The duplex Stirling refrigerator is investigated thermodynamically by considering the effects of constructional and operational parameters which are namely the temperature ratios for heat engine and refrigerator, and the compression ratios for both sides. The primary concern is given to the parametric effects on the overall coefficient of performance of the duplex Stirling refrigerator. The given diagrams provide a design bounds and benchmark results that allows seeing the big picture about the cooling load and heat input relation. Moreover they ease to determine the corresponding work rate to the target cooling load. As regard to the obtained results, a definite region for coefficient of performance of the refrigerator and a definite region for the thermal efficiency of the heat engine of the duplex Stirling are identified.

  16. Environment-friendly refrigeration - Switzerland moves forward

    Stohler, F.

    2003-01-01

    This article presents an interview with Silvan Schaller, president of the Swiss Refrigeration Society SVK and head of a leading Swiss industrial refrigeration company, on the subject of the implementation of new Swiss materials legislation that regulates the use of various refrigerants. In particular, the co-operation between the Society and the regulatory authorities is stressed. The reasons behind the regulations - the protection of the environment and, in particular, the ozone layer - are discussed as are the efforts required by industry to meet them. Future refrigeration technologies and the choice of refrigerants are examined. Measures that will have to be taken by the companies in the refrigeration sector, such as the additional training of personnel and the monitoring of the disposal of wastes, are examined. For the future, the goal of reducing the energy consumption of refrigeration installations is noted

  17. Magnon-driven quantum dot refrigerators

    Wang, Yuan; Huang, Chuankun; Liao, Tianjun; Chen, Jincan, E-mail: jcchen@xmu.edu.cn

    2015-12-18

    Highlights: • A three-terminal quantum dot refrigerator is proposed. • The effects of magnetic field, applied voltage, and polarization are considered. • The region that the system can work as a refrigerator is determined. • Two different magnon-driven quantum dot refrigerators are compared. - Abstract: A new model of refrigerator consisting of a spin-splitting quantum dot coupled with two ferromagnetic reservoirs and a ferromagnetic insulator is proposed. The rate equation is used to calculate the occupation probabilities of the quantum dot. The expressions of the electron and magnon currents are obtained. The region that the system can work in as a refrigerator is determined. The cooling power and coefficient of performance (COP) of the refrigerator are derived. The influences of the magnetic field, applied voltage, and polarization of two leads on the performance are discussed. The performances of two different magnon-driven quantum dot refrigerators are compared.

  18. Lipid Panel

    ... A routine cardiac risk assessment typically includes a fasting lipid panel. Beyond that, research continues into the usefulness of other non-traditional markers of cardiac risk, such as Lp-PLA 2 . A health practitioner may choose to evaluate one or more ...

  19. Leaching of cadmium and tellurium from cadmium telluride (CdTe) thin-film solar panels under simulated landfill conditions.

    Ramos-Ruiz, Adriana; Wilkening, Jean V; Field, James A; Sierra-Alvarez, Reyes

    2017-08-15

    A crushed non-encapsulated CdTe thin-film solar cell was subjected to two standardized batch leaching tests (i.e., Toxicity Characteristic Leaching Procedure (TCLP) and California Waste Extraction Test (WET)) and to a continuous-flow column test to assess cadmium (Cd) and tellurium (Te) dissolution under conditions simulating the acidic- and the methanogenic phases of municipal solid waste landfills. Low levels of Cd and Te were solubilized in both batch leaching tests (<8.2% and <3.6% of added Cd and Te, respectively). On the other hand, over the course of 30days, 73% of the Cd and 21% of the Te were released to the synthetic leachate of a continuous-flow column simulating the acidic landfill phase. The dissolved Cd concentration was 3.24-fold higher than the TCLP limit (1mgL -1 ), and 650-fold higher than the maximum contaminant level established by the US-EPA for this metal in drinking water (0.005mgL -1 ). In contrast, the release of Cd and Te to the effluent of the continuous-flow column simulating the methanogenic phase of a landfill was negligible. The remarkable difference in the leaching behavior of CdTe in the columns is related to different aqueous pH and redox conditions promoted by the microbial communities in the columns, and is in agreement with thermodynamic predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Performance Evaluation of a Solar Adsorption Refrigeration System with a Wing Type Compound Parabolic Concentrator

    Umair, Muhammad; Akisawa, Atsushi; Ueda, Yuki

    2014-01-01

    Simulation study of a solar adsorption refrigeration system using a wing type compound parabolic concentrator (CPC) is presented. The system consists of the wing type collector set at optimum angles, adsorption bed, a condenser and a refrigerator. The wing type collector captures the solar energy efficiently in the morning and afternoon and provides the effective temperature for a longer period of time compared to that achieved by a linear collector. The objectives of the study were to evalua...

  1. Report of the Fusion Energy Sciences Advisory Committee. Panel on Integrated Simulation and Optimization of Magnetic Fusion Systems

    Dahlburg, Jill [General Atomics, San Diego, CA (United States); Corones, James [Krell Inst., Ames, IA (United States); Batchelor, Donald [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bramley, Randall [Indiana Univ., Bloomington, IN (United States); Greenwald, Martin [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Jardin, Stephen [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Krasheninnikov, Sergei [Univ. of California, San Diego, CA (United States); Laub, Alan [Univ. of California, Davis, CA (United States); Leboeuf, Jean-Noel [Univ. of California, Los Angeles, CA (United States); Lindl, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lokke, William [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rosenbluth, Marshall [Univ. of California, San Diego, CA (United States); Ross, David [Univ. of Texas, Austin, TX (United States); Schnack, Dalton [Science Applications International Corporation, Oak Ridge, TN (United States)

    2002-11-01

    Fusion is potentially an inexhaustible energy source whose exploitation requires a basic understanding of high-temperature plasmas. The development of a science-based predictive capability for fusion-relevant plasmas is a challenge central to fusion energy science, in which numerical modeling has played a vital role for more than four decades. A combination of the very wide range in temporal and spatial scales, extreme anisotropy, the importance of geometric detail, and the requirement of causality which makes it impossible to parallelize over time, makes this problem one of the most challenging in computational physics. Sophisticated computational models are under development for many individual features of magnetically confined plasmas and increases in the scope and reliability of feasible simulations have been enabled by increased scientific understanding and improvements in computer technology. However, full predictive modeling of fusion plasmas will require qualitative improvements and innovations to enable cross coupling of a wider variety of physical processes and to allow solution over a larger range of space and time scales. The exponential growth of computer speed, coupled with the high cost of large-scale experimental facilities, makes an integrated fusion simulation initiative a timely and cost-effective opportunity. Worldwide progress in laboratory fusion experiments provides the basis for a recent FESAC recommendation to proceed with a burning plasma experiment (see FESAC Review of Burning Plasma Physics Report, September 2001). Such an experiment, at the frontier of the physics of complex systems, would be a huge step in establishing the potential of magnetic fusion energy to contribute to the world’s energy security. An integrated simulation capability would dramatically enhance the utilization of such a facility and lead to optimization of toroidal fusion plasmas in general. This science-based predictive capability, which was cited in the FESAC

  2. Report of the Fusion Energy Sciences Advisory Committee. Panel on Integrated Simulation and Optimization of Magnetic Fusion Systems

    Dahlburg, Jill; Corones, James; Batchelor, Donald; Bramley, Randall; Greenwald, Martin; Jardin, Stephen; Krasheninnikov, Sergei; Laub, Alan; Leboeuf, Jean-Noel; Lindl, John; Lokke, William; Rosenbluth, Marshall; Ross, David; Schnack, Dalton

    2002-01-01

    Fusion is potentially an inexhaustible energy source whose exploitation requires a basic understanding of high-temperature plasmas. The development of a science-based predictive capability for fusion-relevant plasmas is a challenge central to fusion energy science, in which numerical modeling has played a vital role for more than four decades. A combination of the very wide range in temporal and spatial scales, extreme anisotropy, the importance of geometric detail, and the requirement of causality which makes it impossible to parallelize over time, makes this problem one of the most challenging in computational physics. Sophisticated computational models are under development for many individual features of magnetically confined plasmas and increases in the scope and reliability of feasible simulations have been enabled by increased scientific understanding and improvements in computer technology. However, full predictive modeling of fusion plasmas will require qualitative improvements and innovations to enable cross coupling of a wider variety of physical processes and to allow solution over a larger range of space and time scales. The exponential growth of computer speed, coupled with the high cost of large-scale experimental facilities, makes an integrated fusion simulation initiative a timely and cost-effective opportunity. Worldwide progress in laboratory fusion experiments provides the basis for a recent FESAC recommendation to proceed with a burning plasma experiment (see FESAC Review of Burning Plasma Physics Report, September 2001). Such an experiment, at the frontier of the physics of complex systems, would be a huge step in establishing the potential of magnetic fusion energy to contribute to the world's energy security. An integrated simulation capability would dramatically enhance the utilization of such a facility and lead to optimization of toroidal fusion plasmas in general. This science-based predictive capability, which was cited in the

  3. CO2 as a refrigerant

    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.

  4. A compact rotating dilution refrigerator

    Fear, M. J.; Walmsley, P. M.; Chorlton, D. A.; Zmeev, D. E.; Gillott, S. J.; Sellers, M. C.; Richardson, P. P.; Agrawal, H.; Batey, G.; Golov, A. I.

    2013-10-01

    We describe the design and performance of a new rotating dilution refrigerator that will primarily be used for investigating the dynamics of quantized vortices in superfluid 4He. All equipment required to operate the refrigerator and perform experimental measurements is mounted on two synchronously driven, but mechanically decoupled, rotating carousels. The design allows for relative simplicity of operation and maintenance and occupies a minimal amount of space in the laboratory. Only two connections between the laboratory and rotating frames are required for the transmission of electrical power and helium gas recovery. Measurements on the stability of rotation show that rotation is smooth to around 10-3 rad s-1 up to angular velocities in excess of 2.5 rad s-1. The behavior of a high-Q mechanical resonator during rapid changes in rotation has also been investigated.

  5. Thermal flow regulator of refrigerant

    Dubinskij, S.I.; Savchenko, A.G.; Suplin, V.Z.

    1988-01-01

    A thermal flow regulator of refrigerant for helium flow-type temperature-controlled cryostats based on controlling the channel hydraulic resistance due to variation of the flow density and viscosity during liquid helium transformation into the gaseous state. Behind the regulator both two-phase flow and a heated gas can be produced. The regulator resolution is (7-15)x10 -4 l/mW of liquid helium

  6. Panel discussion

    Anon.

    1980-01-01

    The panel discussion at the 10th Allianz Forum on 'Technology and Insurance' dealt with the following topics: New technologies: energy conversion (coal, petroleum, natural gas, nuclear energy, solar energy); infrastructure (transport, data processing); basic products (metallic materials, chemical products, pharmaceutical products); integrated products (microprocessors, production line machines) as well as new risks: political; general economic (financing, market structure); insurance-related, dangers to persons and property; reduction of risks. (orig.) [de

  7. Cryogen-free dilution refrigerators

    Uhlig, K

    2012-01-01

    We review briefly our first cryogen-free dilution refrigerator (CF-DR) which was precooled by a GM cryocooler. We then show how today's dry DRs with pulse tube precooling have developed. A few examples of commercial DRs are explained and noteworthy features pointed out. Thereby we describe the general advantages of cryogen-free DRs, but also show where improvements are still desirable. At present, our dry DR has a base temperature of 10 mK and a cooling capacity of 700 μW at a mixing chamber temperature of 100 mK. In our cryostat, in most recent work, an additional refrigeration loop was added to the dilution circuit. This 4 He circuit has a lowest temperature of about 1 K and a refrigeration capacity of up to 100 mW at temperatures slightly above 1 K; the dilution circuit and the 4 He circuit can be run separately or together. The purpose of this additional loop is to increase the cooling capacity for experiments where the cooling power of the still of the DR is not sufficient to cool cold amplifiers and cables, e.g. in studies on superconducting quantum circuits or astrophysical applications.

  8. Cryogen-free dilution refrigerators

    Uhlig, K.

    2012-12-01

    We review briefly our first cryogen-free dilution refrigerator (CF-DR) which was precooled by a GM cryocooler. We then show how today's dry DRs with pulse tube precooling have developed. A few examples of commercial DRs are explained and noteworthy features pointed out. Thereby we describe the general advantages of cryogen-free DRs, but also show where improvements are still desirable. At present, our dry DR has a base temperature of 10 mK and a cooling capacity of 700 μW at a mixing chamber temperature of 100 mK. In our cryostat, in most recent work, an additional refrigeration loop was added to the dilution circuit. This 4He circuit has a lowest temperature of about 1 K and a refrigeration capacity of up to 100 mW at temperatures slightly above 1 K; the dilution circuit and the 4He circuit can be run separately or together. The purpose of this additional loop is to increase the cooling capacity for experiments where the cooling power of the still of the DR is not sufficient to cool cold amplifiers and cables, e.g. in studies on superconducting quantum circuits or astrophysical applications.

  9. Superconducting tunnel-junction refrigerator

    Melton, R.G.; Paterson, J.L.; Kaplan, S.B.

    1980-01-01

    The dc current through an S 1 -S 2 tunnel junction, with Δ 2 greater than Δ 1 , when biased with eV 1 +Δ 2 , will lower the energy in S 1 . This energy reduction will be shared by the phonons and electrons. This device is shown to be analogous to a thermoelectric refrigerator with an effective Peltier coefficient π* approx. Δ 1 /e. Tunneling calculations yield the cooling power P/sub c/, the electrical power P/sub e/ supplied by the bias supply, and the cooling efficiency eta=P/sub c//P/sub e/. The maximum cooling power is obtained for eV= +- (Δ 2 -Δ 1 ) and t 1 =T 1 /T/sub c/1 approx. 0.9. Estimates are made of the temperature difference T 2 -T 1 achievable in Al-Pb and Sn-Pb junctions with an Al 2 O 3 tunneling barrier. The performance of this device is shown to yield a maximum cooling efficiency eta approx. = Δ 1 /(Δ 2 -Δ 1 ) which can be compared with that available in an ideal Carnot refrigerator of eta=T 1 /(T 2 -T 1 ). The development of a useful tunnel-junction refrigerator requires a tunneling barrier with an effective thermal conductance per unit area several orders of magnitude less than that provided by the A1 2 O 3 barrier in the Al-Pb and Sn-Pb systems

  10. Effects of hysteresis and Brayton cycle constraints on magnetocaloric refrigerant performance

    Brown, T. D.; Buffington, T.; Shamberger, P. J.

    2018-05-01

    Despite promising proofs of concept, system-level implementation of magnetic refrigeration has been critically limited by history-dependent refrigerant losses that interact with governing thermodynamic cycles to adversely impact refrigeration performance. Future development demands a more detailed understanding of how hysteresis limits performance, and of how different types of cycles can mitigate these limitations, but without the extreme cost of experimental realization. Here, the utility of Brayton cycles for magnetic refrigeration is investigated via direct simulation, using a combined thermodynamic-hysteresis modeling framework to compute the path-dependent magnetization and entropy of a model alloy for a variety of feasible Brayton cycles between 0-1.5 T and 0-5 T. By simultaneously varying the model alloy's hysteresis properties and applying extensions of the thermodynamic laws to non-equilibrium systems, heat transfers and efficiencies are quantified throughout the space of hystereses and Brayton cycles and then compared with a previous investigation using Ericsson cycles. It is found that (1) hysteresis losses remain a critical obstacle to magnetic refrigeration implementation, with efficiencies >80% in the model system requiring hysteresis refrigerant transformation temperatures at the relevant fields; (3) for a given hysteresis and field constraint, Brayton and Ericsson-type cycles generate similar efficiencies; for a given temperature span, Ericsson cycles lift more heat per cycle, with the difference decreasing with the refrigerant heat capacity outside the phase transformation region.

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

    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…

  12. 2013 German refrigeration and air conditioning meeting. Proceedings

    2013-01-01

    These proceedings cover the following main topics: cryoengineering - superconduction / energy storage; cryoapplications in biology and medicine; metrology; adsorption processes; condensation/evaporation; working fluids / simulation; ice production; plants and compressors; expansion and ejectors or recooling; use of cooling (passenger car air conditioning, supermarket); refrigerants; plant efficiency; emissions and legislation; air conditioning and use of heat pumps; air quality and control; building technology and block-type thermal power stations. [de

  13. Functional Dependence of Thermodynamic and Thermokinetic Parameters of Refrigerants Used in Mine Air Refrigerators. Part 1 - Refrigerant R407C

    Nowak, Bernard; Życzkowski, Piotr; Łuczak, Rafał

    2017-03-01

    The authors of this article dealt with the issue of modeling the thermodynamic and thermokinetic properties (parameters) of refrigerants. The knowledge of these parameters is essential to design refrigeration equipment, to perform their energy efficiency analysis, or to compare the efficiency of air refrigerators using different refrigerants. One of the refrigerants used in mine air compression refrigerators is R407C. For this refrigerant, 23 dependencies were developed, determining its thermodynamic and thermokinetic parameters in the states of saturated liquid, dry saturated vapour, superheated vapor, subcooled liquid, and in the two-phase region. The created formulas have been presented in Tables 2, 5, 8, 10 and 12, respectively. It should be noted that the scope of application of these formulas is wider than the range of changes of that refrigerant during the normal operation of mine refrigeration equipment. The article ends with the statistical verification of the developed dependencies. For this purpose, for each model correlation coefficients and coefficients of determination were calculated, as well as absolute and relative deviations between the given values from the program REFPROP 7 (Lemmon et al., 2002) and the calculated ones. The results of these calculations have been contained in Tables 14 and 15.

  14. Leaching of cadmium and tellurium from cadmium telluride (CdTe) thin-film solar panels under simulated landfill conditions

    Ramos-Ruiz, Adriana; Wilkening, Jean V.; Field, James A.; Sierra-Alvarez, Reyes

    2017-01-01

    A crushed non-encapsulated CdTe thin-film solar cell was subjected to two standardized batch leaching tests (i.e., Toxicity Characteristic Leaching Procedure (TCLP) and California Waste Extraction Test (WET)) and to a continuous-flow column test to assess cadmium (Cd) and tellurium (Te) dissolution under conditions simulating the acidic- and the methanogenic phases of municipal solid waste landfills. Low levels of Cd and Te were solubilized in both batch leaching tests (leaching behavior of CdTe in the columns is related to different aqueous pH and redox conditions promoted by the microbial communities in the columns, and is in agreement with thermodynamic predictions. PMID:28472709

  15. 10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.

    2010-01-01

    ... functional characteristics that affect energy consumption. Commercial refrigerator, freezer, and refrigerator... formed by the plane of the door, when the equipment is viewed in cross-section; and (2) For equipment...

  16. HeREF-2003: Helium Refrigeration Techniques

    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...

  17. HeREF-2003 : Helium Refrigeration Techniques

    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 ...

  18. Not all counterclockwise thermodynamic cycles are refrigerators

    Dickerson, R. H.; Mottmann, J.

    2016-06-01

    Clockwise cycles on PV diagrams always represent heat engines. It is therefore tempting to assume that counterclockwise cycles always represent refrigerators. This common assumption is incorrect: most counterclockwise cycles cannot be refrigerators. This surprising result is explored here for quasi-static ideal gas cycles, and the necessary conditions for refrigeration cycles are clarified. Three logically self-consistent criteria can be used to determine if a counterclockwise cycle is a refrigerator. The most fundamental test compares the counterclockwise cycle with a correctly determined corresponding Carnot cycle. Other criteria we employ include a widely accepted description of the functional behavior of refrigerators, and a corollary to the second law that limits a refrigerator's coefficient of performance.

  19. Magnetocaloric refrigeration near room temperature (invited)

    Brueck, E.; Tegus, O.; Thanh, D.T.C.; Buschow, K.H.J.

    2007-01-01

    Modern society relies on readily available refrigeration. The ideal cooling machine would be a compact, solid state, silent and energy-efficient heat pump that does not require maintenance. Magnetic refrigeration has three prominent advantages compared to compressor-based refrigeration. First, there are no harmful gases involved, second it may be built more compact as the working material is a solid and third magnetic refrigerators generate much less noise. Recently, a new class of magnetic refrigerant materials for room-temperature applications was discovered. These new materials have important advantages over existing magnetic coolants: They exhibit a large magnetocaloric effect (MCE) in conjunction with a magnetic phase transition of first order. This MCE is, larger than that of Gd metal, which is used in the demonstration refrigerators built to explore the potential of this evolving technology. In the present review, we compare the different materials considering both scientific aspects and industrial applicability

  20. Optimum operating regimes of common paramagnetic refrigerants

    Wikus, P; Figueroa-Feliciano, E

    2011-01-01

    Adiabatic Demagnetization Refrigerators (ADRs) are commonly used in cryogenic laboratories to achieve subkelvin temperatures. ADRs are also the technology of choice for several space borne instruments which make use of cryogenic microcalorimeters or bolometers {[}1-4]. For these applications, refrigerants with high ratios of cooling capacity to volume, or cooling capacity to mass are usually required. In this manuscript, two charts for the simple selection of the most suitable of several common refrigerants (CAA, CMN, CPA, DGG, FAA, GGG, GLF and MAS) are presented. These graphs are valid for single stage cycles. The selection of the refrigerants is uniquely dependent on the starting conditions of the refrigeration cycle (temperature and magnetic field density) and the desired final temperature. Only thermodynamic properties of the refrigerants have been taken into account, and other important factors such as availability and manufacturability have not been considered. (C) 2011 Elsevier Ltd. All rights reserve...

  1. 2017 German refrigeration and air conditioning meeting. Proceedings

    2017-01-01

    This year's lecture programme includes 117 presentations in the five working departments of DKV and 10 lectures at the special event ''Energy-efficient air conditioning in data centres''. The main topics in the respective departments were: (1) Cryogenics: Space applications; Cryogenic plants; Cryomedicine and cryobiology; Components, developments; Processes and plants; Valves, design. (2) Basics: Evaporation, material values; evaporation, condensation; absorption; adsorption, latent storage; cycle simulation. (3) Components: CO 2 plant engineering and components; refrigerants; process control, adsorption, sublimation and storage technology; refrigerating machine oils, heat exchangers and corrosion; components 4.0, sensors and control technology; simulation of plant processes. (4) Cold application: Application; Application / Natural Refrigerants; Mobile Applications Car; Mobile Applications; Supermarket / Efficiency; Optimization / Efficiency. (5) Air conditioning and heat pump applications: load shifting, smart home, flexibility; heat sources and industrial heat pumps; modelling, simulations; energy concepts heat pumps and photovoltaics; monitoring, evaluation; technology trends / working materials. Six papers are separately analyzed for this database. [de

  2. Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: visibility of simulated microcalcifications.

    Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C

    2013-10-01

    To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer). Aluminum wires and calcium carbonate grains of various sizes were embedded in a paraffin cylinder to simulate imaging of calcifications in a breast. Phantoms were imaged with a benchtop experimental cone beam CT system at various exposure levels. In addition to the Dexela detector, a high pitch (50 μm), thin (150 μm) scintillator CMOS/CsI flat panel detector (C7921CA-09, Hamamatsu Corporation, Hamamatsu City, Japan) and a widely used low pitch (194 μm), thick (600 μm) scintillator aSi/CsI flat panel detector (PaxScan 4030CB, Varian Medical Systems) were also used in scanning for comparison. The images were independently reviewed by six readers (imaging physicists). The MC visibility was quantified as the fraction of visible MCs and measured as a function of the estimated mean glandular dose (MGD) level for various MC sizes and detectors. The modulation transfer functions (MTFs) and detective quantum efficiencies (DQEs) were also measured and compared for the three detectors used. The authors have demonstrated that the use of a high pitch (75 μm) CMOS detector coupled with a thick (500 μm) CsI scintillator helped make the smaller 150-160, 160-180, and 180-200 μm MC groups more visible at MGDs up to 10.8, 9, and 10.8 mGy, respectively. It also made the larger 200-212 and 212-224 μm MC groups more visible at MGDs up to 7.2 mGy. No performance improvement was observed for 224-250 μm or larger size groups. With the higher spatial resolution of the Dexela detector based system, the apparent dimensions and shapes of MCs were more accurately rendered. The results show that with the aforementioned detector, a 73% visibility could be achieved in imaging 160-180 μm MCs as compared to 28% visibility achieved by the low pitch (194 μm) aSi/CsI flat

  3. Ecological optimization for generalized irreversible Carnot refrigerators

    Chen Lingen; Zhu Xiaoqin; Sun Fengrui; Wu Chih

    2005-01-01

    The optimal ecological performance of a Newton's law generalized irreversible Carnot refrigerator with the losses of heat resistance, heat leakage and internal irreversibility is derived by taking an ecological optimization criterion as the objective, which consists of maximizing a function representing the best compromise between the exergy output rate and exergy loss rate (entropy production rate) of the refrigerator. Numerical examples are given to show the effects of heat leakage and internal irreversibility on the optimal performance of generalized irreversible refrigerators

  4. Evaluation of Virtual Refrigerant Mass Flow Sensors

    Kim, Woohyun; Braun, James E.

    2012-01-01

    Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study evaluates three VRMFs for estimating refrigerant mass flow rate. The first model uses a compressor ma...

  5. Adsorption refrigeration technology theory and application

    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

  6. Modelado y simulación de un panel fotovoltaico empleando técnicas de inteligencia artificial; Modeling and simulation of a photovoltaic panel using artificial intelligence techniques

    Adalberto Ospino Castro

    2015-04-01

    Full Text Available El trabajo presenta la modelación del comportamiento energético y la determinación de los parámetros del circuito equivalente de un panel fotovoltaico con el empleo de técnicas de inteligencia artificial. Para tal efecto, se desarrolló en Matlab un algoritmo genético que permite obtener los parámetros físicos no brindados por los fabricantes para la implementación de funciones matemáticas que se homologuen al comportamiento dinámico de un panel solar. El algoritmo desarrollado en Matlab permite determinar, además, la eficiencia del algoritmo seguidor del punto de máxima potencia del inversor, el cual es un parámetro de no simple obtención o no determinado en condiciones de campo. Finalmente, el algoritmo se probó satisfactoriamente en un panel solar monocristalino de 50W obteniendo adecuados resultados en comparación con el modelo experimental para diferentes niveles de irradiación solar. Los resultados demuestran que el proceso desarrollado constituye una herramienta que puede ser aplicada a paneles fotovoltaicos en condiciones de campo. The paper presents the modeling of the energy behavior and determination of equivalent circuit parameters for a photovoltaic panel using artificial intelligence techniques. For this purpose, it was performed a genetic algorithm in Matlab, which calculates the physical parameters not provided by manufacturers to implement mathematical functions that approve the dynamic behavior of a solar panel. In addition, the algorithm can determine the efficiency of the maximum power point tracking algorithm of the inverter, which is a parameter of not simple obtaining or not determined under field conditions. Finally, the algorithm was successfully tested in a monocrystalline solar 50W panel with excellent results, compared to the experimental model for different levels of solar irradiation. The results demonstrate that the developed process is a tool that can be applied to photovoltaic panels under

  7. Simulation and Experimental Study on Effect of Phase Change Material Thickness to Reduce Temperature of Photovoltaic Panel

    Indartono, Y. S.; Prakoso, S. D.; Suwono, A.; Zaini, I. N.; Fernaldi, B.

    2015-09-01

    Solar energy is promising renewable energy which can be applied in Indonesia. Average solar radiation in the country is 4.8 kWh/day/m2. Weakness of silicon-based photovoltaic (PV) is efficiency reduction caused by temperature increase. Many attempts have been done to reduce PV temperature. In previous study, palm oil, which is widely available in Indonesia, is suitable to be used as phase change material (PCM) to reduce PV temperature. In this study, thickness of aluminium rectangular-tube containing phase change material oil is varied. The tube is placed at back part of PV. Numerical and experimental study was done to evaluate the effect of tube thickness to the temperature reduction of the PV. Variation of tube thickness used in the experiment is 50.8mm, 76.2 mm, 101.6 mm. Both studies show that increase of PCM thickness reduces PV temperature. Higher PCM thickness cause large reduction on PV temperature. Simulation result shows there is an optimum thickness of the PCM which is applied to the PV.

  8. Simulation and Experimental Study on Effect of Phase Change Material Thickness to Reduce Temperature of Photovoltaic Panel

    Indartono, Y S; Prakoso, S D; Suwono, A; Zaini, I N; Fernaldi, B

    2015-01-01

    Solar energy is promising renewable energy which can be applied in Indonesia. Average solar radiation in the country is 4.8 kWh/day/m2. Weakness of silicon-based photovoltaic (PV) is efficiency reduction caused by temperature increase. Many attempts have been done to reduce PV temperature. In previous study, palm oil, which is widely available in Indonesia, is suitable to be used as phase change material (PCM) to reduce PV temperature. In this study, thickness of aluminium rectangular-tube containing phase change material oil is varied. The tube is placed at back part of PV. Numerical and experimental study was done to evaluate the effect of tube thickness to the temperature reduction of the PV. Variation of tube thickness used in the experiment is 50.8mm, 76.2 mm, 101.6 mm. Both studies show that increase of PCM thickness reduces PV temperature. Higher PCM thickness cause large reduction on PV temperature. Simulation result shows there is an optimum thickness of the PCM which is applied to the PV. (paper)

  9. United States: refrigeration industry blows hot

    Crawford, J.

    1997-01-01

    In the framework of the Kyoto convention on global warming, the american refrigeration industries have undertaken several organizations and contacts with governments and agencies in order to explain the real issues concerning the effects of refrigerant utilization in refrigerating machines on the greenhouse effect, taking into consideration the commercial impact that a ban on certain refrigerants could have on the industry's business. They argue that HFC utilization in this industry is fundamentally non-emissive and that important improvements have been realized concerning tightness and energy consumption

  10. Rotary magnetic refrigerator for superfluid helium production

    Hakuraku, Y.; Ogata, H.

    1986-01-01

    A new rotary-magnetic refrigerator designed to obtain superfluid helium temperatures by executing a magnetic Carnot cycle is developed. A rotor containing 12 magnetic refrigerants (gadolinium-gallium-garnet) is immersed in liquid helium at 4.2 K and rotated at constant speed in a steady magnetic field distribution. Performance tests demonstrate that the new rotary refrigerator is capable of obtaining a temperature of 1.48 K. The maximum useful cooling power obtained at 1.8 K is 1.81 W which corresponds to a refrigeration efficiency of 34%

  11. Design and dynamic behaviour of a cold storage system combined with a solar powered thermoacoustic refrigerator

    Perier-Muzet, Maxime; Bedecarrats, Jean-Pierre; Stouffs, Pascal; Castaing-Lasvignottes, Jean

    2014-01-01

    A heat powered thermoacoustic refrigerator consists in a thermoacoustic engine that produces acoustic work utilizing heat, coupled to a thermoacoustic cooler that converts this acoustic energy into cooling effect. These machines have already proved their capability in laboratory or in space refrigeration. Previous studies have also demonstrated the possibility of using concentrated solar energy as thermal energy sources for low power heat driven thermoacoustic refrigerators. As other solar refrigeration systems, even if the cooling demand generally increases with the intensity of the solar radiation, one of the major difficulties is to insure a frigorific power supply when there is no, or low, solar radiation. The aim of this work is to study a kW scale solar thermoacoustic refrigerator capable to reach temperatures of the industrial refrigeration domain. This refrigerator is combined with a latent cold storage in order to guarantee a sufficient cooling capacity to face to refrigeration loads in spite of the production fluctuations. A description of the studied prototype is done and the model developed to describe the transient behaviour of the main components of this machine is introduced. The results obtained with a simulation of one week with real solar radiations are presented and the behaviour and the energetic performances of the entire system are analysed. Finally the impact of the sizing of the cold storage system is discussed. With the best storage design, the system is capable to supply a cooling power of 400 W at a temperature equal or lower than −20 °C with an average Coefficient Of Performance of the solar thermoacoustic refrigerator equal to 21%

  12. Development of a battery-free solar refrigerator

    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

  13. Panel surveys

    MADRE, JL; ZUMKELLER, D; CHLOND, B; ARMOOGUM, J

    2004-01-01

    l'analyse du comportement humain constitue un enjeu important dans le domaine des transports, lequel se transforme radicalement sous la pression des évolutions économique, écologique et démographique. les premières grandes études ont commence il y a plus d'une dizaine d'années : parc auto sofres en france, puget sound panel a seattle. cet article fait le bilan de ces expériences et met en évidence les principaux problèmes méthodologiques rencontres tout en proposant de nouvelles directions d'...

  14. Thermal Analysis of Solar Panels

    Barth, Nicolas; de Correia, João Pedro Magalhães; Ahzi, Saïd; Khaleel, Mohammad Ahmed

    In this work, we propose to analyze the thermal behavior of PV panels using finite element simulations (FEM). We applied this analysis to compute the temperature distribution in a PV panel BP 350 subjected to different atmospheric conditions. This analysis takes into account existing formulations in the literature and, based on NOCT conditions, meteorological data was used to validate our approach for different wind speed and solar irradiance. The electrical performance of the PV panel was also studied. The proposed 2D FEM analysis is applied to different region's climates and was also used to consider the role of thermal inertia on the optimization of the PV device efficiency.

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

    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.

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

    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.

  17. Refrigeration generation using expander-generator units

    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.

  18. Prediction of Dangerous Time in Case Hydrocarbon Refrigerant Leaks into Household Refrigerator Cabinet

    Meguro, Takatoshi; Kaji, Nobufuji; Miyake, Kunihiro

    Hydrocarbon refrigerators are now on sale in European countries. However, hydrocarbons are flammable. A common claim is that concentration of hydrocarbon in the refrigerator could exceed the lower explosive limit by a sudden leak and then a spark ignites a flame causing overpressure. There is the need of the studies on potential risks originated from the use of flammable refrigerants. Thus, the flow rate of the fresh air into the refrigerator cabinet has been defined experimentally, and the spatial average concentration in the refrigerator cabinet has been analyzed theoretically to predict the dangerous time in excess of the lower explosive limit.

  19. TRANSPORT PROPERTIES FOR REFRIGERANT MIXTURES

    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.

  20. Refrigeration system with clearance seals

    Holland, N. J.

    1985-01-01

    In a refrigeration system such as a split Stirling system, fluid seals associated with the reciprocating displacer are virtually dragless clearance seals. Movement of the displacer relative to the pressure variations in the working volume of gas is retarded by a discrete braking element. Because it is not necessary that the brake providing any sealing action, the brake can be designed for greater durability and less dependence on ambient and operating temperatures. Similarly, the clearance seal can be formed of elements having low thermal expansion such that the seal is not temperature dependent. In the primary embodiments the braking element is a split friction brake

  1. Refrigeration and air-conditioning

    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

  2. A miniaturized plastic dilution refrigerator

    Bindilatti, V.; Oliveira, N.F.Jr.; Martin, R.V.; Frossati, G.

    1996-01-01

    We have built and tested a miniaturized dilution refrigerator, completely contained (still, heat exchanger and mixing chamber) inside a plastic (PVC) tube of 10 mm diameter and 170 mm length. With a 25 cm 2 CuNi heat exchanger, it reached temperatures below 50 mK, for circulation rates below 70 μmol/s. The cooling power at 100 mK and 63 μmol/s was 45 μW. The experimental space could accommodate samples up to 6 mm in diameter. (author)

  3. The use of cold storage in household refrigerators

    Michael, Y.C.; Yang, K.T.

    1991-01-01

    A simulated household refrigerator was built that utilizes latent Thermal Energy Storage (TES) to reduce the on-off frequency of the compressor. It was found that the on-off frequency was reduced by a factor of six and that the energy consumption was less for a certain range of refrigerated space temperatures. A new evaporator design was used to accommodate the Phase Change Material (PCM). The evaporator consisted of four thin plates filled with PCM which were connected in parallel. The temperature distribution inside the PCM was also measured and the results are discussed. The PCM used was an aqueous solution of propylene glycol. In this paper freezing characteristics as well as some estimate of its latent heat are also discussed

  4. Quality Model of Foodstuff in a Refrigerated Display Cabinet

    Cai, Junping; Risum, Jørgen; Thybo, Claus

    2006-01-01

    Commercial refrigerating systems need to be defrosted regularly to maintain a satisfactory performance. When defrosting the evaporator coil, the air temperature inside the display cabinet will increase, and float outside the normal temperature range for a period of time, the question is what...... happens to the food inside during this period, when we look at the quality factor? This paper discusses quality model of foodstuff, different scenarios of defrost scheme are simulated, questions such as how the defrost temperature and duration influence the food temperature, thus the food quality, as well...... 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....

  5. 46 CFR 147.90 - Refrigerants.

    2010-10-01

    .../ASHRAE 34-78 may be carried as ships' stores. (b) Refrigerants contained in a vessel's operating system... 46 Shipping 5 2010-10-01 2010-10-01 false Refrigerants. 147.90 Section 147.90 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES HAZARDOUS SHIPS' STORES Stowage and Other...

  6. 46 CFR 154.1720 - Indirect refrigeration.

    2010-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Special Design and Operating Requirements § 154.1720 Indirect refrigeration. A refrigeration system that is used to cool acetaldehyde, ethylene...

  7. Refrigeration: Introducing energy saving opportunities for business

    NONE

    2006-04-15

    In some industries, most notably food and drink and chemicals, refrigeration accounts for a significant proportion of overall site energy costs. For instance, in the industrial handling of meat, poultry and fish, it often accounts for 50% of total energy costs. In ice-cream production the proportion is 70%. In a number of commercial sectors, refrigeration also represents a significant proportion of overall energy costs. For example: Cold storage 90%; Food supermarkets 50%; Small shops with refrigerated cabinets 70% or over; Pubs and clubs 30%. Against these high costs, even a small reduction in refrigeration energy use can offer significant cost savings, resulting in increased profits. Energy saving need not be expensive. Energy savings of up to 20% can be realised in many refrigeration plant through actions that require little or no investment. In addition, improving the efficiency and reducing the load on a refrigeration plant can improve reliability and reduce the likelihood of a breakdown. Most organisations can save energy and money on refrigeration by: More efficient equipment; Good maintenance; Housekeeping and control. This publication provides an understanding of the operation of refrigeration systems, identifies where savings can be realised and will enable readers to present an informed case on energy savings to key decision makers within their organisation. (GB)

  8. Energy efficient control of a refrigeration plant

    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...... and the methods are evaluated with respect to energy efficiency....

  9. Sorption compressor/mechanical expander hybrid refrigeration

    Jones, J. A.; Britcliffe, M.

    1987-01-01

    Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansion system or a turbo expansion system with a hydride sorption compressor in place of the usual motor driven piston compressor. To test the feasibility of this system, a commercial Gifford-McMahon refrigerator was tested using hydrogen gas as the working fluid. Although no attempt was made to optimize the system for hydrogen operation, the refrigerator developed 1.3 W at 30 K and 6.6 W at 60 K. The results of the test and of theoretical performances of the hybrid compressor coupled to these expansion systems are presented.

  10. Compatibility of refrigerants and lubricants with elastomers

    Hamed, G.R.; Seiple, R.H.

    1993-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  11. Operating Manual of Helium Refrigerator (Rev. 2)

    Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

    2002-07-01

    A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

  12. Novel materials for laser refrigeration

    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.

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

    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.

  14. Thermoeconomic Optimization of Cascade Refrigeration System Using Mixed Carbon Dioxide and Hydrocarbons at Low Temperature Circuit

    Nasruddin Nasruddin

    2016-12-01

    Full Text Available Many applications and industrial processes require very low cooling temperature, such as cold storage in the biomedical field, requiring temperature below -80 °C. However,single-cycle refrigeration systems can only achieve the effective cooling temperature of -40 °C and, also, the performance of the cycle will decrease drastically for cooling temperatures lower than -35°C. Currently, most of cascade refrigeration systems use refrigerants that have ozone depletion potential (ODP and global warming potential (GWP, therefore, in this study, a cascade system is simulated using a mixture of environmentally friendly refrigerants, namely, carbon dioxide and a hydrocarbon (propane, ethane or ethylene as the refrigerant of the low temperature circuit. A thermodynamic analysis is performed to determine the optimal composition of the mixture of carbon dioxide and hydrocarbons in the scope of certain operating parameters. In addition, an economic analysis was also performed to determine the annual cost to be incurred from the cascade refrigeration system. The multi-objective/thermoeconomic optimization points out optimal operating parameter values of the system, to addressing both exergy efficiency and its relation to the costs to be incurred.

  15. Optimisation of expansion liquefaction processes using mixed refrigerant N_2–CH_4

    Ding, He; Sun, Heng; He, Ming

    2016-01-01

    Highlights: • A refrigerant composition matching method for N_2–CH_4 expansion processes. • Efficiency improvements for propane pre-cooled N_2–CH_4 expansion processes. • The process shows good adaptability to varying natural gas compositions. - Abstract: An expansion process with a pre-cooling system is simulated and optimised by Aspen HYSYS and MATLAB"™. Taking advantage of higher specific refrigeration effect of methane and easily reduced refrigeration temperature of nitrogen, the designed process adopts N_2–CH_4 as a mixed refrigerant. Based on the different thermodynamic properties and sensitivity difference of N_2 and CH_4 over the same heat transfer temperature range, this work proposes a novel method of matching refrigerant composition which aims at single-stage or multi-stage series expansion liquefaction processes with pre-cooling systems. This novel method is applied successfully in propane pre-cooled N_2–CH_4 expansion process, and the unit power consumption is reduced to 7.09 kWh/kmol, which is only 5.35% higher than the global optimised solutions obtained by genetic algorithm. This novel method can fulfil the accomplishments of low energy consumption and high liquefaction rate, and thus decreases the gap between the mixed refrigerant and expansion processes in energy consumption. Furthermore, the high exergy efficiency of the process indicates good adaptability to varying natural gas compositions.

  16. Overview of Air Liquide refrigeration systems between 1.8 K and 200 K

    Gondrand, C.; Durand, F.; Delcayre, F.; Crispel, S.; Baguer, G. M. Gistau

    2014-01-01

    Cryogenic refrigeration systems are necessary for numerous applications. Gas purification and distillation require temperatures between 15 K and 200 K depending on the application, space simulation chambers down to 15 K, superconductivity between 1.8 K and up to 75 K (magnets, cavities or HTS devices like cables, FCL, SMES, etc), Cold Neutron Sources between 15 and 20 K, etc. Air Liquide Advanced Technologies is designing and manufacturing refrigerators since 60 years to satisfy those needs. The step by step developments achieved have led to machines with higher efficiency and reliability. In 1965, reciprocating compressors and Joule Thomson expansion valves were used. In 1969, centripetal expanders began to be used. In 1980, oil lubricated screw compressors took the place of reciprocating compressors and a standard range of Claude cycle refrigerators was developed: the HELIAL series. 1980 was also the time for cryogenic centrifugal compressor development. In 2011, driven by the need for lower operational cost (high efficiency and low maintenance), cycle oil free centrifugal compressors on magnetic bearings were introduced instead of screw compressors. The power extracted by centripetal expanders was recovered. Based on this technology, a range of Turbo-Brayton refrigerators has been designed for temperatures between 40 K and 150 K. On-going development will enable widening the range of Turbo-Brayton refrigerators to cryogenic temperatures down to 15 K.. Cryogenic centrifugal circulators have been developed in order to answer to an increasing demand of 4 K refrigerators able to distribute cold power.

  17. Overview of Air Liquide refrigeration systems between 1.8 K and 200 K

    Gondrand, C.; Durand, F.; Delcayre, F.; Crispel, S.; Baguer, G. M. Gistau

    2014-01-01

    Cryogenic refrigeration systems are necessary for numerous applications. Gas purification and distillation require temperatures between 15 K and 200 K depending on the application, space simulation chambers down to 15 K, superconductivity between 1.8 K and up to 75 K (magnets, cavities or HTS devices like cables, FCL, SMES, etc), Cold Neutron Sources between 15 and 20 K, etc. Air Liquide Advanced Technologies is designing and manufacturing refrigerators since 60 years to satisfy those needs. The step by step developments achieved have led to machines with higher efficiency and reliability. In 1965, reciprocating compressors and Joule Thomson expansion valves were used. In 1969, centripetal expanders began to be used. In 1980, oil lubricated screw compressors took the place of reciprocating compressors and a standard range of Claude cycle refrigerators was developed: the HELIAL series. 1980 was also the time for cryogenic centrifugal compressor development. In 2011, driven by the need for lower operational cost (high efficiency and low maintenance), cycle oil free centrifugal compressors on magnetic bearings were introduced instead of screw compressors. The power extracted by centripetal expanders was recovered. Based on this technology, a range of Turbo-Brayton refrigerators has been designed for temperatures between 40 K and 150 K. On-going development will enable widening the range of Turbo-Brayton refrigerators to cryogenic temperatures down to 15 K.. Cryogenic centrifugal circulators have been developed in order to answer to an increasing demand of 4 K refrigerators able to distribute cold power

  18. Overview of Air Liquide refrigeration systems between 1.8 K and 200 K

    Gondrand, C.; Durand, F.; Delcayre, F.; Crispel, S. [AL-AT, 2 rue de Clémencières, 38360 Sassenage (France); Baguer, G. M. Gistau [CRYOGUY, 44, chemin de la Buisse, 38330 Biviers (France)

    2014-01-29

    Cryogenic refrigeration systems are necessary for numerous applications. Gas purification and distillation require temperatures between 15 K and 200 K depending on the application, space simulation chambers down to 15 K, superconductivity between 1.8 K and up to 75 K (magnets, cavities or HTS devices like cables, FCL, SMES, etc), Cold Neutron Sources between 15 and 20 K, etc. Air Liquide Advanced Technologies is designing and manufacturing refrigerators since 60 years to satisfy those needs. The step by step developments achieved have led to machines with higher efficiency and reliability. In 1965, reciprocating compressors and Joule Thomson expansion valves were used. In 1969, centripetal expanders began to be used. In 1980, oil lubricated screw compressors took the place of reciprocating compressors and a standard range of Claude cycle refrigerators was developed: the HELIAL series. 1980 was also the time for cryogenic centrifugal compressor development. In 2011, driven by the need for lower operational cost (high efficiency and low maintenance), cycle oil free centrifugal compressors on magnetic bearings were introduced instead of screw compressors. The power extracted by centripetal expanders was recovered. Based on this technology, a range of Turbo-Brayton refrigerators has been designed for temperatures between 40 K and 150 K. On-going development will enable widening the range of Turbo-Brayton refrigerators to cryogenic temperatures down to 15 K.. Cryogenic centrifugal circulators have been developed in order to answer to an increasing demand of 4 K refrigerators able to distribute cold power.

  19. Manufacturing A Refrigerator with Heat Recovery Unit

    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

  20. Energy performance of supermarket refrigeration and air conditioning integrated systems working with natural refrigerants

    Cecchinato, Luca; Corradi, Marco; Minetto, Silvia

    2012-01-01

    The current trends in commercial refrigeration aim at reducing the synthetic refrigerant charge, either by minimising the internal volume of the circuit or by utilising natural refrigerants, and at energy saving. The energy efficiency of supermarkets can be improved by optimising components design, recovering thermal and refrigerating energy, adopting innovative technology solutions, integrating the HVAC system with medium temperature and low temperature refrigeration plants and, finally, reducing thermal loads on refrigerated cases. This study aims at investigating the performance of different lay-out and technological solutions where only natural refrigerants are used and at finding the potential for improving energy efficiency over the traditional systems in different climates. In the analysis, chillers and heat pumps working with ammonia or propane, medium temperature systems working with ammonia or propane and carbon dioxide as heat transfer fluid or with carbon dioxide as the refrigerant and low temperature systems working with carbon dioxide are considered and benchmarked with a state-of-the-art HFCs based plant. The most efficient investigated solution enables an annual energy saving higher than 15% with respect to the baseline solution for all the considered climates. - Highlights: ► Different natural refrigerants supermarket HVAC and R integrated systems are analysed. ► Some of the proposed solutions offer a significant benefit over the baseline one. ► Up to 18.7% energy saving is achieved in the considered climates. ► The refrigeration unit condensation by the AC chiller offers the poorest results.

  1. The use of a sparse planar array sensor for measurement of the acoustic properties of panel materials at simulated ocean conditions

    Beamiss, Graham A.; Robinson, Stephen P.; Wang, Lian S.; Hayman, Gary; Humphrey, Victor F.; Smith, John D.; Martin, M. J.

    2015-01-01

    Characterisation of the acoustic properties of materials for underwater acoustics is often carried out by measuring the transmitted and/or reflected pressure signals after insonification of a test panel by an incident acoustic wave. For this method to be reliable, the incident and transmitted (or reflected) signals arriving at the hydrophone receiver should be well separated in time (enabling windowing techniques to be applied), and the diffracted signals from the panel edge should not contam...

  2. Panel Discussion

    Langer, James

    1997-03-01

    Panelists: Arthur Bienenstock, Stanford University Cherry Ann Murray, Lucent Technologies Venkatesh Narayanamurti, University of California-Santa Barbara Paul Peercy, SEMI-SEMATECH Robert Richardson, Cornell University James Roberto, Oak Ridge National Laboratory The Board on Physics and Astronomy is undertaking a series of reassessments of all branches of physics as the foundation of a new physics survey. As part of this project, a Committee on Condensed Matter and Materials Physics has been established under the leadership of Venkatesh Narayanamurti of the University of California-Santa Barbara. The committee has been working since June on a study that will include an illustrative recounting of major recent achievements; identification of new opportunities and challenges facing the field; and articulation-for leaders in government, industry, universities, and the public at large-of the important roles played by the field in modern society. An especially urgent issue is how to maintain the intellectual vitality of condensed matter and materials physics, and its contributions to the well-being of the United States, in an era of limited resources. The forum will feature a panel of materials researchers who are members of the Committee on Condensed Matter and Materials Physics. They will give a brief report on the status of the study and engage in a dialogue with the audience about issues facing the condensed matter and materials physics community. Broad community input is vital to the success of the study. Please come and make your voice heard!

  3. Experimental Results of Integrated Refrigeration and Storage System Testing

    Notardonato, W. U.; Johnson, W. L.; Jumper, K.

    2009-01-01

    Launch operations engineers at the Kennedy Space Center have identified an Integrated Refrigeration and Storage system as a promising technology to reduce launch costs and enable advanced cryogenic operations. This system uses a close cycle Brayton refrigerator to remove energy from the stored cryogenic propellant. This allows for the potential of a zero loss storage and transfer system, as well and control of the state of the propellant through densification or re-liquefaction. However, the behavior of the fluid in this type of system is different than typical cryogenic behavior, and there will be a learning curve associated with its use. A 400 liter research cryostat has been designed, fabricated and delivered to KSC to test the thermo fluid behavior of liquid oxygen as energy is removed from the cryogen by a simulated DC cycle cryocooler. Results of the initial testing phase focusing on heat exchanger characterization and zero loss storage operations using liquid oxygen are presented in this paper. Future plans for testing of oxygen densification tests and oxygen liquefaction tests will also be discussed. KEYWORDS: Liquid Oxygen, Refrigeration, Storage

  4. Static analysis of triple-effect adsorption refrigeration with compressor

    Fumi Watanabe

    2017-03-01

    Full Text Available In order to improve the efficiency of the adsorption refrigeration cycle, this study proposes a triple-effect adsorption refrigeration cycle equipped with a compressor. This cycle can run in order to create a large variation in adsorbent concentration range by the compressor, even if there is little temperature variation in the desorption and adsorption processes. The objective of this study is to clarify the effect that regulating adsorption pressure using a compressor has on the adsorption refrigeration cycle, and to that end cycle efficiency was calculated using a static analysis based on a state of equilibrium. As a results from the simulation, the triple-effect cycles can operate by regulating adsorption pressure. Both COP and exergy efficiency can be improved by a factor of 1.2 if the cycled is regulated the adsorption pressure of each cycle rather than using a shared adsorption pressure. For heat sources in the temperature range of 70–100 °C, this method is superior in terms of COP and exergy efficiency. COP values of approximately 1.7–1.8 can be obtained, which is three times higher than single-effect cycles. The triple-effect cycles have one-third the SCE of single-effect cycles but about the same SCE as double-effect cycles.

  5. Refrigerating liquid prototype for LED's thermal management

    Faranda, Roberto; Guzzetti, Stefania; Lazaroiu, George Cristian; Leva, Sonia

    2012-01-01

    The heat management is the critical factor for high performance operation of LED. A new heat management application of refrigerating liquid integrated within a fabricated prototype is proposed and investigated. A series of experiments considering different heights of liquid level were performed to evaluate the heat dissipation performance and optical characteristics of the refrigerating liquid based prototype. The results reveal that the junction temperature decreases as the level of refrigerating liquid increases. The experimental results report that the refrigerating liquid reduces the junction temperature, and can positively influence the luminous radiation performances. An optimization investigation of the proposed solution was carried out to find an optimum thermal performance. The experiments indicated that refrigerating liquid cooling is a powerful way for heat dissipation of high power LEDs, and the fabrication of prototype was feasible and useful. - Highlights: ► New heat management application of refrigerating liquid on a fabricated LED prototype. ► Thermal models setup and comparison between the classical and the new solutions. ► The impact of refrigerating liquid level on LED thermal and luminous performances. ► The relationship between different levels of liquid with LED prototype performances.

  6. Data-Driven Control of Refrigeration System

    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...... traditionally are a pressure and a temperature sensor. In this thesis, a novel maximum slope-seeking (MSS) control method is developed. This has resulted in a control implementation, which successfully has been able to control the evaporator superheat in four widely different refrigeration system test...... problems. The method utilizes the qualitative nonlinearity in the system and harmonic analysis of a perturbation signal to reach an unknown, but suitable, operating point. Another important control task in refrigeration systems is to maintain the temperature of the refrigerated space or foodstuff within...

  7. 46 CFR 111.79-15 - Receptacles for refrigerated containers.

    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...

  8. Hepatic (Liver) Function Panel

    ... Educators Search English Español Blood Test: Hepatic (Liver) Function Panel KidsHealth / For Parents / Blood Test: Hepatic (Liver) ... kidneys ) is working. What Is a Hepatic (Liver) Function Panel? A liver function panel is a blood ...

  9. Comprehensive metabolic panel

    Metabolic panel - comprehensive; Chem-20; SMA20; Sequential multi-channel analysis with computer-20; SMAC20; Metabolic panel 20 ... Chernecky CC, Berger BJ. Comprehensive metabolic panel (CMP) - blood. In: ... Tests and Diagnostic Procedures . 6th ed. St Louis, MO: ...

  10. Load forecasting of supermarket refrigeration

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

    2016-01-01

    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...... for handling the non-linear relations and that after applying an auto-regressive noise model the one-step ahead residuals do not contain further significant information....... 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...

  11. Bearing construction for refrigeration compresssor

    Middleton, Marc G.; Nelson, Richard T.

    1988-01-01

    A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings.

  12. PIPER Continuous Adiabatic Demagnetization Refrigerator

    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.

  13. Classification of refrigerants; Classification des fluides frigorigenes

    NONE

    2001-07-01

    This document was made from the US standard ANSI/ASHRAE 34 published in 2001 and entitled 'designation and safety classification of refrigerants'. This classification allows to clearly organize in an international way the overall refrigerants used in the world thanks to a codification of the refrigerants in correspondence with their chemical composition. This note explains this codification: prefix, suffixes (hydrocarbons and derived fluids, azeotropic and non-azeotropic mixtures, various organic compounds, non-organic compounds), safety classification (toxicity, flammability, case of mixtures). (J.S.)

  14. Two-phase flow in refrigeration systems

    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

  15. ESO2 Optimization of Supermarket Refrigeration Systems

    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...... in the supermarket. The first approach to solve this problem is to design an overall control system which coordinates the compressor capacity and the current refrigeration load. The drawback of this approach is the complexity of the single controller. The solution is investigated in the first part of the report...

  16. Behavior of FFC refrigerants in the presence of refrigerant oils. Oelverhalten chlorfreier Kaeltemittel

    Burke, M.; Kruse, H. (Hannover Univ. (Germany, F.R.). Inst. fuer Kaeltetechnik und Angewandte Waermetechnik)

    1990-01-01

    Looking for substitutes for the ozone-depleting refrigerants R12 and R22, investigations were made of the miscibility of FFC refrigerants (R23 - trifluoromethane CHF{sub 3}, R134a - tetrafluoroethane CH{sub 3}-CHF{sub 2}, and R152a - difluoroethane CH{sub 3}-CHF{sub 2}) with refrigerator oils. First experimental results reveal the refrigerants' behavior when mixed with mineral oils, alkylbenzene, PAG and ester-based oils. Mixtures of above refrigerants, especially R134a/R152a and R23/R152a as binary nonazeotropic mixtures, are considered conceivable substitutes. While addition of R23 reduces the mixture's flammability, addition of R152a improves the solubility of R134a in refrigerant oils. (orig./HW).

  17. Refrigerant charge management in a heat pump water heater

    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. Numerical modelling and analysis of a room temperature magnetic refrigeration system

    Petersen, Thomas Frank

    This thesis presents a two-dimensional mathematical model of an Active Magnetic Regenerator (AMR) system which is used for magnetic refrigeration at room temperature. The purpose of the model is to simulate a laboratory-scale AMR constructed at Risø National Laboratory. The AMR model geometry....... The AMR performs a cyclic process, and to simulate the AMR refrigeration cycle the model starts from an initial temperature distribution in the regenerator and fluid channel and takes time steps forward in time until the cyclical steady-state is obtained. The model can therefore be used to study both...... transient and steady-state phenomena. The AMR performance can be evaluated in terms of the no-load temperature span as well as the refrigeration capacity and the COP. The AMR model was verified extensively and it was concluded that the model has energy conservation and that the solution is independent...

  19. New magnetic refrigeration materials for the liquefaction of hydrogen

    Gschneidner, K.A.; Takeya, H.; Moorman, J.O.; Pecharsky, V.K.; Malik, S.K.; Zimm, C.B.

    1994-01-01

    Five heavy lanthanide ferromagnetic intermetallic compounds were studied as potential magnetic refrigerants for the liquefaction of hydrogen gas. (Dy 0.5 Er 0.5 )Al 2 and TbNi 2 appear to be better refrigerants than GdPd for a Joule-Brayton cycle refrigerator, while (Gd 0.54 Er 0.46 )AlNi seems to be a suitable refrigerant for an Ericsson cycle refrigerator

  20. Application of Cascade Refrigeration System with Mixing Refrigerant in Cold Air Cutting

    Yang, Y.; Tong, M. W.; Yang, G.; Wang, X. P.

    In the mechanical cutting process, the replacement of traditional cutting solution with cold air can avoid the pollution of environment. In order to high efficient the refrigerating device and flexible adjust the temperature of cold air, it is necessary to use cascade refrigeration system to supply cool quantity for the compressed air. The introduction of a two-component non-azeotropic mixing refrigerant into the cryogenic part of the cascade system, can effectively solve the problems of the system working at too high pressure and the volume expanding of refrigerant in case of the cascade refrigeration sets closed down. However, the filling ratio of mixing refrigerants impact on the relationships among the closing down pressure, refrigerating output and refrigerating efficiency. On the basis of computing and experiment, the optimal mixing ratio of refrigerant R22/R13 and a low temperature of -60° were obtained in this study. A cold air injecting device possessing high efficiency in energy saving has also been designed and manufactured. The cold air, generated from this cascade system and employed in a cutting process, takes good comprehensive effects on machining and cutting.

  1. Optimization of a solar driven absorption refrigerator in the transient regime

    Hamed, Mouna; Fellah, Ali; Ben Brahim, Ammar

    2012-01-01

    Highlights: ► Dynamic behavior of a solar absorption refrigerator endoreversible model. ► Using the principles of classical thermodynamics, mass and heat transfers. ► Minimizing heat exchange time to reach maximum performances. ► Major influence of the collector temperature on the model’s characteristics. ► Analogous effects of both the thermal load and the thermal conductance. -- Abstract: This contribution deals with the theoretical study in dynamic mode of an absorption refrigerator endoreversible model. The system is a cold generating station driven by solar energy. The main elements of the cycle are a refrigerated space, an absorption refrigerator and a solar collector form. A mathematical model is developed. It combines the classical thermodynamics and mass and heat transfers principles. The numerical simulation is made for different operating and conceptual conditions. A global minimizing time optimization is performed in view to reach maximum performances. Appropriate dimensionless groups are defined. The results are presented in normalized charts for general applications. The collector temperature presents major influence on the conceptual and functional characteristics compared to the stagnation temperature influence. On the other hand the thermal load in the refrigerated space and the thermal conductance of the walls has analogous effects, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar collector based energy systems.

  2. Development of a hybrid refrigerator combining thermoelectric and vapor compression technologies

    Vian, J.G.; Astrain, D.

    2009-01-01

    A domestic refrigerator with three compartments has been developed: refrigerator compartment, at 4 deg. C (vapor compression cooling system); freezer compartment, at -22 deg. C (vapor compression cooling system); and a new super-conservation compartment, at 0 deg. C (thermoelectric cooling system). The thermoelectric system designed for the super-conservation compartment eliminates the oscillation of its temperature due to the start and stop compressor cycles, obtaining a constant temperature and thus, a better preservation of the food. For the design and optimization of this application, a computational model, based in the numerical method of finite differences, has been developed. This model allows to simulate the complete hybrid refrigerator (vapor compression-thermoelectricity). The accuracy of the model has been experimentally checked, with a maximum error of 1.2 deg. C for temperature values, and 8% for electric power consumption. By simulations with the computational model, the design of the refrigerator has been optimized, obtaining a final prototype highly competitive, by the features on food preservation and power consumption: 1.15 kW h per day (48.1 W) for an ambient temperature of 25 deg. C. According to European rules, this power consumption value means that this new refrigerator could be included on energy efficiency class B.

  3. ENERGY STAR Certified Commercial Refrigerators and Freezers

    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...

  4. ENERGY STAR Laboratory Grade Refrigerators and Freezers

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 1.0 ENERGY STAR Program Requirements for Laboratory Grade Refrigerators and Freezers that...

  5. Refrigeration system having standing wave compressor

    Lucas, Timothy S.

    1992-01-01

    A compression-evaporation refrigeration system, wherein gaseous compression of the refrigerant is provided by a standing wave compressor. The standing wave compressor is modified so as to provide a separate subcooling system for the refrigerant, so that efficiency losses due to flashing are reduced. Subcooling occurs when heat exchange is provided between the refrigerant and a heat pumping surface, which is exposed to the standing acoustic wave within the standing wave compressor. A variable capacity and variable discharge pressure for the standing wave compressor is provided. A control circuit simultaneously varies the capacity and discharge pressure in response to changing operating conditions, thereby maintaining the minimum discharge pressure needed for condensation to occur at any time. Thus, the power consumption of the standing wave compressor is reduced and system efficiency is improved.

  6. Shuttle Kit Freezer Refrigeration Unit Conceptual Design

    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.

  7. Defrost Temperature Termination in Supermarket Refrigeration Systems

    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.

  8. Auto-refrigerating cascade for superconducting applications

    Forrest, S.M.; Hall, P.H.; Missimer, D.J.

    1987-01-01

    Extremely low temperatures, in the range of 230 to 90 K, are achieved in a single circuit compression refrigeration system operated by a conventional compressor. The system relies upon a series of intermediate cooling stages. The refrigerant is a mixture and the system employs fractional condensation, distillation, phase separation and intermediate heat transfer. Each stage includes the steps of withdrawing a portion of the liquid condensate from the compressed vapor-liquid refrigerant mixture which enters the stage. The withdrawn condensate is then throttled to a lower pressure and is mixed with the refrigerant being recycled to the compressor from the final evaporator. Evaporating the throttled condensate absorbs heat from and at least partially condenses the compressed uncondensed vapor in the compressed mixture

  9. ACTIVATED CARBON/REFRIGERANT COMBINATIONS FOR ...

    ES Obe

    2001-03-01

    Mar 1, 2001 ... to solar adsorption refrigeration machines are estimated. ... heat, activated carbon/ammonia requires the use of advanced flat-plate collectors such as those with multiple ... the thermodynamic performance of zeolite-water.

  10. Freezing and refrigerated storage in fisheries

    Johnston, W. A

    1994-01-01

    ...; the factors affecting cold storage conditions, etc. In addition, the publication describes the methods used to calculate cold storage refrigeration loads as well as the costs of freezing and cold storage...

  11. Commercial refrigeration - An overview of current status

    Mota Babiloni, Adrián; Navarro Esbri, Joaquin; BARRAGÁN CERVERA, ÁNGEL; Moles, Francisco; Peris, Bernardo; Verdú Martín, Gumersindo Jesús

    2015-01-01

    Commercial Refrigeration comprises food freezing and conservation in retail stores and supermarkets, so, it is one of the most relevant energy consumption sectors, and its relevance is increasing. This paper reviews the most recent developments in commercial refrigeration available in literature and presents a good amount of results provided these systems, covering some advantages and disadvantages in systems and working fluids. Latest researches are focused on energy savings to reduce CO2 in...

  12. A review of linear compressors for refrigeration

    Liang, Kun

    2017-01-01

    Linear compressor has no crank mechanism compared with conventional reciprocating compressor. This allows higher efficiency, oil-free operation, lower cost and smaller size when linear compressors are used for vapour compression refrigeration (VCR) system. Typically, a linear compressor consists of a linear motor (connected to a piston) and suspension springs, operated at resonant frequency. This paper presents a review of linear compressors for refrigeration system. Different designs and mod...

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

    Yamanaka, H; Nakagawa, M

    2013-01-01

    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.

  14. A miniature adsorption3HE refrigerator

    Duband, L.; Ravex, A.; Lange, A.

    1991-01-01

    A self-contained, recyclable laboratory 3 He refrigerator has been developed. The refrigerator is very compact, portable and is designed to be safe and reliable. The unit can easily be installed on the cold plate of a superfluid 4 He cryostat. Once bolted on the cold plate, operation of the refrigerator is controlled by a single heater. In this new design the refrigerator has a cylindrical geometry. The adsorption pump is placed above the condensation point to prevent convection during the condensation phase and to improve the pumping speed. The inhibition of convection reduces the load on the 4 He bath and increases the condensation efficiency. This refrigeration technique has great potential for space applications. The absence of moving parts makes the system reliable and vibration free. Its simplicity and the absence of external components facilitate its integration on a cryostat. In fact, a rocket-borne 3 He refrigerator has already been successfully flown and has demonstrated the feasibility of this method

  15. Optimizing the Thermoacoustic Pulse Tube Refrigerator Performances

    E. V. Blagin

    2014-01-01

    Full Text Available The article deals with research and optimization of the thermoacoustic pulse tube refrigerator to reach a cryogenic temperature level. The refrigerator is considered as a thermoacoustic converter based on the modified Stirling cycle with helium working fluid. A sound pressure generator runs as a compressor. Plant model comprises an inner heat exchanger, a regenerative heat exchanger, a pulse tube, hot and cold heat exchangers at its ends, an inertial tube with the throttle, and a reservoir. A model to calculate the pulse tube thermoacoustic refrigerator using the DeltaEC software package has been developed to be a basis for calculation techniques of the pulse tube refrigerator. Momentum, continuity, and energy equations for helium refrigerant are solved according to calculation algorithm taking into account the porosity of regenerator and heat exchangers. Optimization of the main geometric parameters resulted in decreasing temperature of cold heat exchanger by 41,7 K. After optimization this value became equal to 115,01 K. The following parameters have been optimized: diameters of the feeding and pulse tube and heat exchangers, regenerator, lengths of the regenerator and pulse and inertial tubes, as well as initial pressure. Besides, global minimum of temperatures has been searched at a point of local minima corresponding to the optimal values of abovementioned parameters. A global-local minima difference is 0,1%. Optimized geometric and working parameters of the thermoacoustic pulse tube refrigerator are presented.

  16. Nonconvex model predictive control for commercial refrigeration

    Gybel Hovgaard, Tobias; Boyd, Stephen; Larsen, Lars F. S.; Bagterp Jørgensen, John

    2013-08-01

    We consider the control of a commercial multi-zone refrigeration system, consisting of several cooling units that share a common compressor, and is used to cool multiple areas or rooms. In each time period we choose cooling capacity to each unit and a common evaporation temperature. The goal is to minimise the total energy cost, using real-time electricity prices, while obeying temperature constraints on the zones. We propose a variation on model predictive control to achieve this goal. When the right variables are used, the dynamics of the system are linear, and the constraints are convex. The cost function, however, is nonconvex due to the temperature dependence of thermodynamic efficiency. To handle this nonconvexity we propose a sequential convex optimisation method, which typically converges in fewer than 5 or so iterations. We employ a fast convex quadratic programming solver to carry out the iterations, which is more than fast enough to run in real time. We demonstrate our method on a realistic model, with a full year simulation and 15-minute time periods, using historical electricity prices and weather data, as well as random variations in thermal load. These simulations show substantial cost savings, on the order of 30%, compared to a standard thermostat-based control system. Perhaps more important, we see that the method exhibits sophisticated response to real-time variations in electricity prices. This demand response is critical to help balance real-time uncertainties in generation capacity associated with large penetration of intermittent renewable energy sources in a future smart grid.

  17. Study on the coupling performance of a turboexpander compressor applied in cryogenic reverse Brayton air refrigerator

    Yang, Shanju; Chen, Shuangtao; Chen, Xingya; Zhang, Xingqun; Hou, Yu

    2016-01-01

    Highlights: • Numerical simulations on expansion and compression processes were carried out. • A coupling model was built based on analysis and simulation and verified by test. • Relations and interactions among coupling parameters were quantitatively described. • When T_0_C = 0.39 MPa, the cooling capacity of refrigerator reached 221 W at 129.6 K. - Abstract: A small cryogenic reverse Brayton air refrigerator with turboexpander compressor (TEC) is presented in this study. Because of stable process, simple matching between expander and brake blower, and easy regulation, a turboexpander with brake blower is usually used in small reverse Brayton refrigerator. However, a turboexpander with brake blower just consumes and wastes the output energy during the enthalpy drop. In contrast, the output energy of TEC is absorbed by its coupled compressor for recycling. Thus when employing a TEC, the reverse Brayton refrigerator will achieve lower refrigeration temperature, larger cooling capacity and more effective energy use. TEC overall performance, which has an important impact on the refrigerator thermal performance, is mainly determined by the coupling between expander and compressor. In a TEC, the compressor and expander should seek balance among energy, rotating speed, mass flow rate and pressure, though restricted by individual working characteristics. The coupling relations among compressor efficiency, expander efficiency, compressor pressure ratio and expander expansion ratio are quite complex. In this study, theoretical coupling analysis between expander and compressor was conducted. The aerodynamic performances of compressor and expander were calculated using CFX simulation with SST model. The performance curves of compressor and expander were obtained through simulation results, which were validated by experimental data. Based on the coupling analysis and numerical simulations, the automatic coupling model between compression process and expansion process

  18. Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications

    Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C.

    2013-01-01

    Purpose: To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer).

  19. Plant-wide dynamic and static optimisation of supermarket refrigeration systems

    Green, Torben; Izadi-Zamanabadi, Roozbeh; Razavi-Far, Roozbeh

    2013-01-01

    Optimising the operation of a supermarket refrigeration system under dynamic as well as steadystate conditions is addressedin thispaper. For thispurpose anappropriateperformance function that encompasses food quality, system efficiency, and also component reliability is established. The choice...... in the system. Simulation results is used to substantiate the suggestedmethodology....

  20. Relationship between composition of mixture charged and that in circulation in an auto refrigerant cascade and a J-T refrigerator operating in liquid refrigerant supply mode

    Sreenivas, Bura; Nayak, H. Gurudath; Venkatarathnam, G.

    2017-01-01

    The composition of the refrigerant mixture in circulation during steady state operation of J-T and allied refrigerators is not the same as that charged due to liquid hold up in the heat exchangers and phase separators, as well as the differential solubility of different refrigerant components in the compressor lubricating oil. The performance of refrigerators/liquefiers operating on mixed refrigerant cycles is dependent on the mixture composition. It is therefore important to charge the right mixture that results in an optimum composition in circulation during steady state operation. The relationship between the charged and circulating composition has been experimentally studied in a J-T refrigerator operating in the liquid refrigerant supply (LRS) mode and an auto refrigerant cascade refrigerator (with a phase separator) operating in the gas refrigerant supply (GRS) mode. The results of the study are presented in this work. The results show that the method presented earlier for J-T refrigerators operating in GRS mode is also applicable in the case of refrigerators studied in this work.

  1. HFC perspectives in air-conditioning and refrigeration; Perspectives HFC en A/C et refrigeration

    Fauvarque, P [ELF Atochem, Centre d` Application de Lavallois, 92 (France)

    1998-12-31

    This paper is a series of transparencies dealing with the development of substitutes for the replacement of the R-22 refrigerant in air-conditioning systems (R-134a, R-407C, R-410A), and in industrial refrigeration systems of agriculture and food industry (R-134a and R-404A). (J.S.)

  2. HFC perspectives in air-conditioning and refrigeration; Perspectives HFC en A/C et refrigeration

    Fauvarque, P. [ELF Atochem, Centre d`Application de Lavallois, 92 (France)

    1997-12-31

    This paper is a series of transparencies dealing with the development of substitutes for the replacement of the R-22 refrigerant in air-conditioning systems (R-134a, R-407C, R-410A), and in industrial refrigeration systems of agriculture and food industry (R-134a and R-404A). (J.S.)

  3. Suitability criterion for a refrigerant for use in solar operated sorption refrigerator

    Tabassum, S.A.; Mir, M.S.

    1996-01-01

    The thermodynamics of a sorption refrigeration cycle has been discussed representing the cycle on a clapeyron digram. The minimum generation temperature required has been determined using the 'd-a' equation which represents the sorption equilibrium of the pair, and Gibbs free energy relation. The mathematical relation developed provides a totally new basis for determination of suitability of a particular refrigerant. (author)

  4. Suitability criterion for a refrigerant for use in solar operated sorption refrigerator

    Tabassum, S A; Mir, M S [University of Engineering and Technology, Lahore (Pakistan). Dept. of Mechanical Engineering

    1996-06-01

    The thermodynamics of a sorption refrigeration cycle has been discussed representing the cycle on a clapeyron digram. The minimum generation temperature required has been determined using the `d-a` equation which represents the sorption equilibrium of the pair, and Gibbs free energy relation. The mathematical relation developed provides a totally new basis for determination of suitability of a particular refrigerant. (author).

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

    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.

  6. Interface Behavior in Functionally Graded Ceramics for the Magnetic Refrigeration: Numerical Modeling

    Jabbari, Masoud; Spangenberg, Jon; Hattel, Jesper Henri

    2013-01-01

    The active magnetic regenerator refrigerator is currently the most common magnetic refrigeration device for near room temperature applications, and it is driven by the magnetocaloric effect in the regenerator material. In order to make this efficient, a graded configuration of the magnetocaloric...... the influence of the different material properties, i.e. the density and the viscosity, on the interface between the flows, since this is highly important for the efficiency of the device. The Newtonian flow behavior with relatively high viscosity is assumed for each fluid and used in the simulation...

  7. Computational Investigation on the performance of thermo-acoustically driven pulse tube refrigerator

    Skaria, Mathew; Rasheed, K. K. Abdul; Shafi, K. A.; Kasthurirengan, S.; Behera, Upendra

    2017-02-01

    A Thermoacoustic Pulse Tube Refrigeration (TAPTR) system employs a thermo acoustic engine as the pressure wave generator instead of mechanical compressor. Such refrigeration systems are highly reliable due to the absence of moving components, structural simplicity and the use of environmental friendly working fluids. In the present work, a traveling wave thermoacoustic primmover (TWTAPM) has been developed and it is coupled to a pulse tube cryocooler. The performance of TAPTR depends on the operating and working fluid parameters. Simulation studies of the system has been performed using ANSYS Fluent and compared with experimental results.

  8. Modeling of a Von Platen-Munters diffusion absorption refrigeration cycle

    Agostini, Bruno; Agostini, Francesco; Habert, Mathieu

    2016-09-01

    This article presents a thermodynamical model of a Von-Platen diffusion absorption refrigeration cycle for power electronics applications. It is first validated by comparison with data available in the literature for the classical water-ammonia-helium cycle for commercial absorption fridges. Then new operating conditions corresponding to specific ABB applications, namely high ambient temperature and new organic fluids combinations compatible with aluminium are simulated and discussed. The target application is to cool power electronics converters in harsh environments with high ambient temperature by providing refrigeration without compressor, for passive components losses of about 500 W, with a compact and low cost solution.

  9. Refrigerated Warehouse Demand Response Strategy Guide

    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.

  10. A new compressed air energy storage refrigeration system

    Wang Shenglong; Chen Guangming; Fang Ming; Wang Qin

    2006-01-01

    In this study, a new compressed air energy storage (CAES) refrigeration system is proposed for electrical power load shifting application. It is a combination of a gas refrigeration cycle and a vapor compression refrigeration cycle. Thermodynamic calculations are conducted to investigate the performance of this system. Economic analysis is performed to study the operating cost of the system, and comparison is made with a vapor compression refrigeration system and an ice storage refrigeration system. The results indicate that the CAES refrigeration system has the advantages of simple structure, high efficiency and low operating cost

  11. ARTI refrigerant database. Quarterly report, March--May 1997

    Calm, J.M.

    1997-05-01

    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 an 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. 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.

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

    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.

  13. The application of ionizers in domestic refrigerators for reduction in airborne and surface bacteria.

    Kampmann, Y; Klingshirn, A; Kloft, K; Kreyenschmidt, J

    2009-12-01

    To investigate the antimicrobial effect of ionization on bacteria in household refrigerators. Ionizer prototypes were tested with respect to their technical requirements and their ability to reduce surface and airborne contamination in household refrigerators. Ion and ozone production of the tested prototypes were measured online by an ion meter and an ozone analyser. The produced negative air ion (NAI) and ozone amounts were between 1.2 and 3.7 x 10(6) NAI cm(-3) and 11 and 19 ppb O(3), respectively. To test the influence of ionization on surface contamination, different materials like plastic, glass and nutrient agar for simulation of food were inoculated with bacterial suspensions. The reduction rate was dependent on surface properties. The effect on airborne bacteria was tested by nebulization of Bacillus subtilis- suspension (containing spores) aerosols in refrigerators with and without an ionizer. A clear reduction in air contamination because of ionization was measured. The antimicrobial effect is dependent on several factors, such as surface construction and airflow patterns within the refrigerator. Ionization seems to be an effective method for reduction in surface and airborne bacteria. This study is an initiation for a new consumer tool to decontaminate domestic refrigerators.

  14. Combined Brayton-JT cycles with refrigerants for natural gas liquefaction

    Chang, Ho-Myung; Park, Jae Hoon; Lee, Sanggyu; Choe, Kun Hyung

    2012-06-01

    Thermodynamic cycles for natural gas liquefaction with single-component refrigerants are investigated under a governmental project in Korea, aiming at new processes to meet the requirements on high efficiency, large capacity, and simple equipment. Based upon the optimization theory recently published by the present authors, it is proposed to replace the methane-JT cycle in conventional cascade process with a nitrogen-Brayton cycle. A variety of systems to combine nitrogen-Brayton, ethane-JT and propane-JT cycles are simulated with Aspen HYSYS and quantitatively compared in terms of thermodynamic efficiency, flow rate of refrigerants, and estimated size of heat exchangers. A specific Brayton-JT cycle is suggested with detailed thermodynamic data for further process development. The suggested cycle is expected to be more efficient and simpler than the existing cascade process, while still taking advantage of easy and robust operation with single-component refrigerants.

  15. Capacitance sensor for void fraction measurement in a natural circulation refrigeration circuit

    Rocha, Marcelo S.; Cabral, Eduardo L.L.; Simoes-Moreira, Jose R.

    2009-01-01

    Natural circulation is widely used in nuclear reactors for residual heat refrigeration. In this work, a conductance probe is designed and constructed to measure the instantaneous bulk void fraction in a vertical tube section. This probe is installed in a natural circulation refrigeration loop designed to simulate a nuclear reactor primary refrigeration circuit. During the operation of the natural circulation loop several gas-liquid flow patterns are observed, including oscillatory flow. The instantaneous signal generated by the capacitance probe allows the calculation of the two-phase flow void fraction. The void fraction obtained by the probe will be compared with the theoretical void fraction calculated by the computational program RELAP5/MOD3.2.2 gamma. The probe design and electronics, as well as the previous results obtained are presented and discussed. (author)

  16. The effect of coolants on the performance of magnetic micro-refrigerators.

    Silva, D J; Bordalo, B D; Pereira, A M; Ventura, J; Oliveira, J C R E; Araújo, J P

    2014-06-01

    Magnetic refrigeration is an alternative cooling technique with envisaged technological applications on micro- and opto-electronic devices. Here, we present a magnetic micro-refrigerator cooling device with embedded micro-channels and based on the magnetocaloric effect. We studied the influence of the coolant fluid in the refrigeration process by numerically simulating the heat transfer processes using the finite element method. This allowed us to calculate the cooling power of the device. Our results show that gallium is the most efficient coolant fluid and, when used with Gd5Si2Ge2, a maximum power of 11.2 W/mm3 at a working frequency of -5 kHz can be reached. However, for operation frequencies around 50 Hz, water is the most efficient fluid with a cooling power of 0.137 W/mm3.

  17. Fast and Reliable Primary Frequency Reserves From Refrigerators with Decentralized Stochastic Control

    Vrettos, Evangelos; Ziras, Charalampos; Andersson, Goran

    2016-01-01

    in the controller to account for thermostat resolution limitations, and finally, we modify the control design to account for refrigerator door openings. Extensive simulations with actual frequency signal data and with different aggregation sizes, load characteristics, and control parameters, demonstrate......Due to increasing shares of renewable energy sources, more frequency reserves are required to maintain power system stability. In this paper, we present a decentralized control scheme that allows a large aggregation of refrigerators to provide Primary Frequency Control (PFC) reserves to the grid...... based on local frequency measurements and without communication. The control is based on stochastic switching of refrigerators depending on the frequency deviation. We develop methods to account for typical lockout constraints of compressors and increased power consumption during the startup phase...

  18. Design and Performance Analysis of a Biodiesel Engine Driven Refrigeration System for Vaccine Storage

    K Kamsuk

    2013-06-01

    Full Text Available A compact, stand-alone, refrigeration module powered by a small biodiesel engine for vaccine storage in rural use was proposed. The engine was of single cylinder, four-stroke, directinjection with displacement of 0.296 cm3 and compression ratio of 20:1. The refrigeration system was modified from an automotive vapor compression system. The system performance was analytically investigated. From the simulation, it was found to have acceptable operation over a range of speeds and loads. Performance of the system in terms of fuel consumption and torque tended to decrease with an increase in engine speed. The modular system was able to operate at cooling loads above 4.6 kW, with proper speed ratio between the engine and the compressor. Overall, primary energy ratio of the refrigeration was found to be maximum at 0.54.

  19. Comparison between a 1D and a 2D numerical model of an active magnetic regenerative refrigerator

    Petersen, Thomas Frank; Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

    2008-01-01

    The active magnetic regenerator (AMR) refrigeration system represents an environmentally attractive alternative to vapour-compression refrigeration. This paper compares the results of two numerical AMR models: (1) a 1D finite difference model and (2) a 2D finite element model. Both models simulate...... a reciprocating AMR and can determine the cyclical steady-state temperature profile of the system as well as performance parameters such as the refrigeration capacity, the work input and the coefficient of performance (COP). The models are used to analyse an AMR with a regenerator made of flat parallel plates...... results of overall results such as the refrigeration capacity but that a 2D model is required for a detailed analysis of the phenomena occurring inside the AMR....

  20. Analytical minimization of overall conductance and heat transfer area in refrigeration and heat pump systems and its numerical confirmation

    Sarkar, J.; Bhattacharyya, Souvik; Ram Gopal, M.

    2007-01-01

    Minimization of heat exchanger area for a specified capacity is very important in the design of refrigeration and heat pump systems, yielding space, weight and cost benefits. In this study, minimization of overall conductance and total area per unit capacity of refrigeration and heat pump systems has been performed analytically. The analysis is performed for constant temperature heat sources and sinks considering both internal and external irreversibilities. Expressions are obtained for optimum hot and cold side refrigerant temperatures, conductance and heat exchanger area ratios. The analytical results have been confirmed by those obtained from a detailed numerical simulation of actual ammonia based refrigeration and heat pump systems, and good agreement is observed. Such theoretical models can be employed as simple yet effective design guidelines for real systems as demonstrated here

  1. Influence of Oil on Refrigerant Evaporator Performance

    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%.

  2. Quantum heat engines and refrigerators: continuous devices.

    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.

  3. Automatically varying the composition of a mixed refrigerant solution for single mixed refrigerant LNG (liquefied natural gas) process at changing working conditions

    Xu, Xiongwen; Liu, Jinping; Cao, Le; Pang, Weiqiang

    2014-01-01

    The SMR (single mixed refrigerant) process is widely used in the small- and medium-scale liquefaction of NG (natural gas). Operating the MR (mixed-refrigerant) process outside of the design specifications is difficult but essential to save energy. Nevertheless, it is difficult to realize because the process needs to alter the working refrigerant composition. To address this challenge, this study investigated the performance diagnosis mechanism for SMR process. A control strategy was then proposed to control the changes in working refrigerant composition under different working conditions. This strategy separates the working refrigerant flow in the SMR process into three flows through two phase separators before it flows into the cold box. The first liquid flow is rich in the high-temperature component (isopentane). The second liquid flow is rich in the middle-temperature components (ethylene and propane), and the gas flow is rich in the low-temperature components (nitrogen and methane). By adjusting the flow rates, it is easy to decouple the control variables and automate the system. Finally, this approach was validated by process simulation and shown to be highly adaptive and exergy efficient in response to changing working conditions. - Highlights: • The performance diagnosis mechanism of SMR LNG process is studied. • A measure to automatically change the operation composition as per the working conditions is proposed for SMR process. • SMR process simulation is performed to verify the validity of the control solution. • The control solution notably improves the energy efficiency of SMR process at changing working condition

  4. COP improvement of refrigerator/freezers, air-conditioners, and heat pumps using nonazeotropic refrigerant mixtures

    Westra, Douglas G.

    1993-01-01

    With the February, 1992 announcement by President Bush to move the deadline for outlawing CFC (chloro-fluoro-carbon) refrigerants from the year 2000 to the year 1996, the refrigeration and air-conditioning industries have been accelerating their efforts to find alternative refrigerants. Many of the alternative refrigerants being evaluated require synthetic lubricants, are less efficient, and have toxicity problems. One option to developing new, alternative refrigerants is to combine existing non-CFC refrigerants to form a nonazeotropic mixture, with the concentration optimized for the given application so that system COP (Coefficient Of Performance) may be maintained or even improved. This paper will discuss the dilemma that industry is facing regarding CFC phase-out and the problems associated with CFC alternatives presently under development. A definition of nonazeotropic mixtures will be provided, and the characteristics and COP benefits of nonazeotropic refrigerant mixtures will be explained using thermodynamic principles. Limitations and disadvantages of nonazeotropic mixtures will be discussed, and example systems using such mixtures will be reviewed.

  5. 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

    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.

  6. Modelling refrigerant distribution in microchannel evaporators

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

    2009-01-01

    of the refrigerant distribution is carried out for two channels in parallel and for two different cases. In the first case maldistribution of the inlet quality into the channels is considered, and in the second case a non-uniform airflow on the secondary side is considered. In both cases the total mixed superheat...... 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...

  7. Model Based Control of Refrigeration Systems

    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...... control is to let an optimization procedure take over the task of operating the refrigeration system and thereby replace the role of the operator in the traditional control structure. In the context of refrigeration systems, the idea is to divide the optimizing control structure into two parts: A part...... optimizing the steady state operation "set-point optimizing control" and a part optimizing dynamic behaviour of the system "dynamical optimizing control". A novel approach for set-point optimization will be presented. The general idea is to use a prediction of the steady state, for computation of the cost...

  8. Designing a magnet for magnetic refrigeration

    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 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...

  9. Basics of Low-temperature Refrigeration

    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.

  10. Materials for Room Temperature Magnetic Refrigeration

    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 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...

  11. Basics of Low-temperature Refrigeration

    Alekseev, A [Linde AG, Munich (Germany)

    2014-07-01

    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.

  12. Performance characteristics of a quantum Diesel refrigeration cycle

    He Jizhou; Wang Hao; Liu Sanqiu

    2009-01-01

    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

  13. Refrigerator Optimal Scheduling to Minimise the Cost of Operation

    Bálint Roland

    2016-12-01

    Full Text Available The cost optimal scheduling of a household refrigerator is presented in this work. The fundamental approach is the model predictive control methodology applied to the piecewise affine model of the refrigerator.

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

    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.

  15. A Cold Cycle Dilution Refrigerator for Space Applications, Phase I

    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....

  16. OPTIONS FOR REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    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...

  17. Performance of a Throttle Cycle Refrigerator with Nitrogen-Hydrocarbon and Argon-Hydrocarbon Mixtures

    Venkatarathnam, G.; Senthil Kumar, P.; Srinivasa Murthy, S.

    2004-06-01

    Throttle cycle refrigerators are a class of vapor compression refrigerators that can provide refrigeration at cryogenic temperatures and operate with refrigerant mixtures. The performance of our prototype refrigerators with nitrogen-hydrocarbon, nitrogen-hydrocarbon-helium and argon-hydrocarbon refrigerant mixtures is presented in this paper.

  18. Second-law-based analysis of vapor-compression refrigeration cycles: Analytical equations for COP and new insights into features of refrigerants

    Ma, Weiwu; Fang, Song; Su, Bo; Xue, Xinpei; Li, Min

    2017-01-01

    Highlights: • Second-law analysis leads to analytical COP formulas for refrigeration cycles. • Relative errors of the analytical equations are smaller than ±5.0%. • The analytical expressions characterize the influence of refrigerants. • Global entropy analysis elucidates the impact of cycle processes on COP. - Abstract: This article reports a second-law-based analysis of the vapor-compression refrigeration cycle, which leads to a set of explicit theoretical formulas for the coefficient of performance (COP). These analytical expressions provide a fast and accurate approach to computer simulations of the vapor-compression cycle without recourse to thermodynamic diagrams or equations of state. The second-law-based analysis yields specific expressions for the entropy generations of irreversible processes, enabling us to evaluate the thermodynamic features of the refrigerant and to elucidate the thermodynamic mechanisms behind the effects of the cycle processes, including superheat, subcooling, and throttling processes. In particular, these processes can interact, therefore this paper presents a global entropy generation analysis for evaluating the impact of the interacted processes on COP.

  19. Toxicity Data to Determine Refrigerant Concentration Limits

    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.

  20. Hepatitis virus panel

    ... page: //medlineplus.gov/ency/article/003558.htm Hepatitis virus panel To use the sharing features on this page, please enable JavaScript. The hepatitis virus panel is a series of blood tests used ...

  1. Antinuclear antibody panel

    ... page: //medlineplus.gov/ency/article/003535.htm Antinuclear antibody panel To use the sharing features on this page, please enable JavaScript. The antinuclear antibody panel is a blood test that looks at ...

  2. Paneling architectural freeform surfaces

    Eigensatz, Michael; Kilian, Martin; Schiftner, Alexander; Mitra, Niloy J.; Pottmann, Helmut; Pauly, Mark

    2010-01-01

    with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication

  3. Acoustically Tailored Composite Rotorcraft Fuselage Panels

    Hambric, Stephen; Shepherd, Micah; Koudela, Kevin; Wess, Denis; Snider, Royce; May, Carl; Kendrick, Phil; Lee, Edward; Cai, Liang-Wu

    2015-01-01

    A rotorcraft roof sandwich panel has been redesigned to optimize sound power transmission loss (TL) and minimize structure-borne sound for frequencies between 1 and 4 kHz where gear meshing noise from the transmission has the most impact on speech intelligibility. The roof section, framed by a grid of ribs, was originally constructed of a single honeycomb core/composite face sheet panel. The original panel has coincidence frequencies near 700 Hz, leading to poor TL across the frequency range of 1 to 4 kHz. To quiet the panel, the cross section was split into two thinner sandwich subpanels separated by an air gap. The air gap was sized to target the fundamental mass-spring-mass resonance of the double panel system to less than 500 Hz. The panels were designed to withstand structural loading from normal rotorcraft operation, as well as 'man-on-the-roof' static loads experienced during maintenance operations. Thin layers of VHB 9469 viscoelastomer from 3M were also included in the face sheet ply layups, increasing panel damping loss factors from about 0.01 to 0.05. Measurements in the NASA SALT facility show the optimized panel provides 6-11 dB of acoustic transmission loss improvement, and 6-15 dB of structure-borne sound reduction at critical rotorcraft transmission tonal frequencies. Analytic panel TL theory simulates the measured performance quite well. Detailed finite element/boundary element modeling of the baseline panel simulates TL slightly more accurately, and also simulates structure-borne sound well.

  4. Numerical investigation of boiling heat transfer on hydrocarbon mixture refrigerant in vertical rectangular minichannel

    Huixing Li; Yu Liu

    2016-01-01

    In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat t...

  5. THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

    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.

  6. THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

    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

  7. Designing a magnet for magnetic refrigeration

    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

  8. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    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. Energy analysis of a supermarket refrigeration system

    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...

  10. Dilution refrigeration with multiple mixing chambers

    Coops, G.M.

    1981-01-01

    A dilution refrigerator is an instrument to reach temperatures in the mK region in a continuous way. The temperature range can be extended and the cooling power can be enlarged by adding an extra mixing chamber. In this way we obtain a double mixing chamber system. In this thesis the theory of the multiple mixing chamber is presented and tested on its validity by comparison with the measurements. Measurements on a dilution refrigerator with a circulation rate up to 2.5 mmol/s are also reported. (Auth.)

  11. Modeling Supermarket Refrigeration Systems for Demand-Side Management

    Jakob Stoustrup

    2013-02-01

    Full Text Available Modeling of supermarket refrigeration systems for supervisory control in the smart grid is presented in this paper. A modular modeling approach is proposed in which each module is modeled and identified separately. The focus of the work is on estimating the power consumption of the system while estimating the cold reservoir temperatures as well. The models developed for each module as well as for the overall integrated system are validated by real data collected from a supermarket in Denmark. The results show that the model is able to estimate the actual electrical power consumption with a high fidelity. Moreover a simulation benchmark is introduced based on the produced model for demand-side management in smart grid. Finally, a potential application of the proposed benchmark in direct control of the power/energy consumption is presented by a simple simulation example.

  12. Thermodynamic analysis of a novel exhaust heat-driven non-adiabatic ejection-absorption refrigeration cycle using R290/oil mixture

    Li, Keqiao; Cai, Dehua; Liu, Yue; Jiang, Jingkai; Sun, Wei; He, Guogeng

    2017-01-01

    Graphical abstract: A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle using R290/refrigeration oil has been thermodynamically analyzed. Influences of the ejector and the non-adiabatic absorber applications on the system performance and other system operation parameters have been investigated. The simulation results will be of great help to the miniaturization and practical application of the air-cooled absorption refrigeration system. - Highlights: • A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle is proposed. • Influences of the ejector and the air-cooled non-adiabatic absorber applications on the system performance are investigated. • Variations of system performance and other system operation parameters are investigated. • R290/refrigeration oil mixture used as working pairs is analyzed. - Abstract: This paper thermodynamically analyzes a novel air-cooled non-adiabatic ejection-absorption refrigeration cycle with R290/oil mixture driven by exhaust heat. An ejector located at the upstream of the non-adiabatic absorber is employed to improve the cycle performance. Variations of COP, circulation ratio and component heat load of the system as a function of generating temperature, pressure ratio, absorption temperature, condensing temperature and evaporating temperature have been investigated in this work. The simulation results show that, compared with the conventional absorption refrigeration cycle, this non-adiabatic ejection-absorption refrigeration cycle has higher absorption efficiency, better performance, wider working condition range and lower total heat load and its COP can reach as high as 0.5297. The implementation of the ejector and the non-adiabatic absorber helps to realize the miniaturization and wider application of the absorption refrigeration system. In addition, R290/oil mixture is a kind of highly potential working pairs for absorption refrigeration.

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

    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. Experimental investigation and exergy analysis of a triple fluid vapor absorption refrigerator

    Jemaa, Radhouane Ben; Mansouri, Rami; Boukholda, Ismail; Bellagi, Ahmed

    2016-01-01

    Highlights: • Experimental study on a commercial triple fluid vapor absorption refrigerator performed. • An Aspen-hysys model developed and validated with experimental measurements. • Exergy analysis of the unit performed and discussed. • Absorber identified as largest source of irreversibility, followed by solution heat exchanger. - Abstract: This paper presents an energy and exergy analyses of a triple fluid vapor absorption refrigerator working with ammonia as refrigerant, water as absorbent and hydrogen as auxiliary gas. The experimental setup is constituted of a commercial unit equipped with the appropriate metrology. The temperature at the inlet and outlet of every component of the machine, as well as the cabinet and ambient temperature are continuously measured and monitored. A simulation model of the machine is developed using the process simulator Aspen-Hysys. The thermodynamic analysis includes energy and exergy efficiency calculations, destroyed exergy evaluation and degradation of the coefficient of performance (COP) in each component of the refrigerator. The results indicate that the absorber exhibits the largest source of irreversibility followed by the solution heat exchanger. These two components alone are at the origin of 63% of the total degradation of COP.

  15. Fuzzy Control of Cold Storage Refrigeration System with Dynamic Coupling Compensation

    Xiliang Ma

    2018-01-01

    Full Text Available Cold storage refrigeration systems possess the characteristics of multiple input and output and strong coupling, which brings challenges to the optimize control. To reduce the adverse effects of the coupling and improve the overall control performance of cold storage refrigeration systems, a control strategy with dynamic coupling compensation was studied. First, dynamic model of a cold storage refrigeration system was established based on the requirements of the control system. At the same time, the coupling between the components was studied. Second, to reduce the adverse effects of the coupling, a fuzzy controller with dynamic coupling compensation was designed. As for the fuzzy controller, a self-tuning fuzzy controller was served as the primary controller, and an adaptive neural network was adopted to compensate the dynamic coupling. Finally, the proposed control strategy was employed to the cold storage refrigeration system, and simulations were carried out in the condition of start-up, variable load, and variable degree of superheat, respectively. The simulation results verify the effectiveness of the fuzzy control method with dynamic coupling compensation.

  16. Numerical analysis on the frosting performance of a fin-tube evaporator for a refrigerator

    Lee, Moo Yeon; Jang, Yong Hee; Kim, Yong Chan; Lee, Ho Sung

    2008-01-01

    The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ± 10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at 3 .deg. C and 80% is increased 40% than that of -3 .deg. C and 80%, and the frost thickness at 3 .deg. C and 90% is increased 30% than that of 3 .deg. C and 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition

  17. Fault diagnosis and refrigerant leak detection in vapour compression refrigeration systems

    Tassou, S.A.; Grace, I.N. [Brunel University, Uxbridge (United Kingdom). Department of Mechanical Engineering

    2005-08-01

    The environmental impact of refrigeration systems can be reduced by operation at higher efficiency and reduction of refrigerant leakage. Refrigerant loss contributes both directly and indirectly to global warming through inefficient system operation, increased power consumption and greenhouse gas emissions and higher maintenance costs. Existing sensor-based leak detection methods are limited by the inability to detect gradual leakage and the need for careful sensor location. There is a requirement for a real-time performance monitoring approach to leak detection and fault diagnosis which overcomes these disadvantages. This paper reports on the development of a fault diagnosis and refrigerant leak detection system based on artificial intelligence and real-time performance monitoring. The system has been used successfully to distinguish between faulty and fault free operation, steady-state and transient operation, leakage and over charge conditions. Work currently underway is aimed at testing additional fault conditions and establishing further rules to distinguish between these patterns. (author)

  18. An optimal power management system for a regenerative auxiliary power system for delivery refrigerator trucks

    Mohagheghi Fard, Soheil; Khajepour, Amir

    2016-01-01

    Highlights: • A new anti-idling system for refrigerator trucks is proposed. • This system enables regenerative braking. • An innovative two-level controller is proposed for the power management system. • A fast dynamic programming technique to find real-time SOC trajectory is proposed. • In addition to idling elimination, this system reduces fuel consumption. - Abstract: Engine idling of refrigerator trucks during loading and unloading contributes to greenhouse gas emissions due to their increased fuel consumption. This paper proposes a new anti-idling system that uses two sources of power, battery and engine-driven generator, to run the compressor of the refrigeration system. Therefore, idling can be eliminated because the engine is turned OFF and the battery supplies auxiliary power when the vehicle is stopped for loading or unloading. This system also takes advantage of regenerative braking for increased fuel savings. The power management of this system needs to satisfy two requirements: it must minimize fuel consumption in the whole cycle and must ensure that the battery has enough energy for powering the refrigeration system when the engine is OFF. To meet these objectives, a two-level controller is proposed. In the higher level of this controller, a fast dynamic programming technique that utilizes extracted statistical features of drive and duty cycles of a refrigerator truck is used to find suboptimal values of the initial and final SOC of any two consecutive loading/unloading stops. The lower level of the controller employs an adaptive equivalent fuel consumption minimization (A-ECMS) to determine the split ratio of auxiliary power between the generator and battery for each segment with initial and final SOC obtained by the high-level controller. The simulation results confirm that this new system can eliminate idling of refrigerator trucks and reduce their fuel consumption noticeably such that the cost of replacing components is recouped in a

  19. Performance evaluation of an ejector subcooled vapor-compression refrigeration cycle

    Xing, Meibo; Yan, Gang; Yu, Jianlin

    2015-01-01

    Highlights: • An ejector subcooled vapor-compression refrigeration cycle is proposed. • The performance of the cycle with ejector subcooling is evaluated theoretically. • Increase in refrigeration capacity can be achieved by the ejector subcooled cycle. • The new cycle exhibits higher COP compared to the basic single-stage cycle. • Performance of the new cycle depends on the operation pressures of the ejector. - Abstract: In this study, a novel vapor-compression refrigeration cycle with mechanical subcooling using an ejector is proposed to improve the performance of a conventional single-stage vapor-compression refrigeration cycle. In the theoretical study, a mathematical model is developed to predict the performance of the cycle by using R404A and R290, and then compared with that of the conventional refrigeration cycle. The simulation results show that the performance of the ejector subcooled cycle is better than that of the conventional cycle. When the evaporator temperature ranges from −40 to −10 °C and the condenser temperature is 45 °C, the novel cycle displays volumetric refrigeration capacity improvements of 11.7% with R404A and 7.2% with R290. And the novel cycle achieves COP improvements of 9.5% with R404A and 7.0% with R290. In addition, the improvement of the COP and cooling capacity of this novel cycle largely depends on the operation pressures of the ejector. The potential practical advantages offered by the cycle may be worth further attention in future studies

  20. Second law comparison of single effect and double effect vapour absorption refrigeration systems

    Gomri, Rabah

    2009-01-01

    In this paper a comparative study between single effect and double effect absorption refrigeration systems with identical cold output is carried out. Simulation results were used to study the influence of the various operating parameters on the performance coefficient, the thermal loads of the components, exergetic efficiency (rational efficiency) and the total change in exergy of the two systems. It is concluded that the COP of double effect system is approximately twice the COP of single effect system but the exergetic efficiency of double effect system increase slightly compared to the exergetic efficiency of single effect system. It is found that for each condenser and evaporator temperature, there is an optimum generator temperature where the total change in exergy of the single effect and double effect absorption refrigeration systems is minimum. At this point the COP and exergetic efficiency of the systems become maximum. In this study and when the evaporation temperature is varied from 4 deg. C to 10 deg. C, condenser and absorber temperatures are varied from 33 deg. C to 39 deg. C and generator (HPG) temperature is varied from 60 deg. C to 190 deg. C the maximum COP values of the single effect refrigeration systems are in the range of 0.73-0.79 and for double effect refrigeration systems are in the range of 1.22-1.42. The maximum exergetic efficiency values of the single effect refrigeration systems are in the range of 12.5-23.2% and for double effect refrigeration systems are in the range of 14.3-25.1%.

  1. Modelling of a chemisorption refrigeration and power cogeneration system

    Bao, Huashan; Wang, Yaodong; Roskilly, Anthony Paul

    2014-01-01

    Highlights: • An adsorption cogeneration was proposed and simulated for cooling and electricity. • A dynamic model was built and studied to demonstrate the variability of the system. • A dynamic model included the complex coupling of thermodynamic and chemical kinetic. • Mutual constrains between main components and optimisation methods were discussed. • The highest theoretical COP and exergy efficiency of cogeneration is 0.57 and 0.62. - Abstract: The present work for the first time explores the possibility of a small-scale cogeneration unit by combining solid–gas chemisorption refrigeration cycle and a scroll expander. The innovation in this work is the capability of producing refrigeration and electricity continuously and simultaneously without aggravating the energy scarcity and environmental impact. Individual modelling for each component, which has been validated by experimental data, was firstly investigated in order to identify the proper operation condition for the cogeneration mode achieving 1000 W power output. Subsequently, with the integrated modelling of two components the cogeneration performance was studied to demonstrate the viability of this concept. However, because of the mutual constraint between the chemisorption and the expansion when they link in series, the power output of the cogeneration mode was only around one third of the original expectation under the same condition identified in the individual modelling. Methods of improving the global performance including the selection of reactive mediums were also discussed and would be of referable value for the future practical investigation

  2. Assessment of propane/commercial butane mixtures as possible alternatives to R134a in domestic refrigerators

    Fatouh, M.; El Kafafy, M.

    2006-01-01

    The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. The performance characteristics of domestic refrigerators were predicted over a wide range of evaporation temperatures (-35 to -10 o C) and condensation temperatures (40-60 deg. C) for various working fluids such as R134a, propane, commercial butane and propane/iso-butane/n-butane mixtures with various propane mass fractions. The performance characteristics of the considered domestic refrigerator were identified by the coefficient of performance (COP), volumetric cooling capacity, cooling capacity, condenser capacity, input power to compressor, discharge temperature, pressure ratio and refrigerant mass flow rate. The results showed that pure propane could not be used as a drop in replacement for R134a in domestic refrigerators because of its high operating pressures and low COP. Commercial butane yields many desirable characteristics but requires a compressor change. The coefficient of performance of the domestic refrigerator using a ternary hydrocarbon mixture with propane mass fractions from 0.5 to 0.7 is higher than that of R134a. Comparison among the considered working fluids confirmed that the average refrigerant mass flow rate of the propoane/commercial butane mixture is 50% lower than that of R134a. Also, the results indicated that R134a and the propoane/commercial butane mixture with 60% propane mass concentration have approximately the same values of saturation pressure, compressor discharge temperature, condenser heat load, input power, cooling capacity and volumetric cooling capacity. However, the pressure ratio of the hydrocarbon mixture with 60% propane is lower than that of R134a by about 11.1%. Finally, the reported results confirmed that the propane/iso-butane/n-butane mixture with 60% propane is the best drop in replacement for R134a in domestic refrigerators under normal

  3. Evaluation of design options for improving the energy efficiency of an environmentally safe domestic refrigerator-freezer

    Vineyard, E.A.; Sand, J.R. [Oak Ridge National Lab., TN (United States); Bohman, R.H.

    1995-03-01

    In order to reduce greenhouse emissions from power plants and respond to regulatory actions arising from the National Appliance Energy Conservation Act (NAECA), several design options were investigated for improving the energy efficiency of a conventionally designed, domestic refrigerator-freezer. The options, such as improved cabinet insulation and high-efficiency compressor and fans, were incorporated into a prototype refrigerator-freezer cabinet and refrigeration system to produce a unit that is superior from an environmental viewpoint due to its lower energy consumption and the use of refrigerant HFC-134a as a replacement for CFC-12. Baseline energy performance of the original 1993 production refrigerator-freezer, along with cabinet heat load and compressor calorimeter test results, were extensively documented to provide a firm basis for experimentally measured energy savings. A detailed refrigerator system computer model was used to evaluate the energy savings for several design modifications that, collectively, could achieve a targeted energy consumption of 1.00 kWh/d for a 20 ft{sup 3} (570 l) top-mount, automatic-defrost, refrigerator-freezer. The energy consumption goal represents a 50% reduction in the 1993 NAECA standard for units of this size. Following the modeling simulation, laboratory prototypes were fabricated and tested to experimentally verify the analytical results and aid in improving the model in those areas where discrepancies occurred. While the 1.00 kWh/d goal was not achieved with the modifications, a substantial energy efficiency improvement of 22% (1.41 kWh/d) was demonstrated using near-term technologies. It is noted that each improvement exacts a penalty in terms of increased cost or system complexity/reliability. Further work on this project will analyze cost-effectiveness of the design changes and investigate alternative, more-elaborate, refrigeration system changes to further reduce energy consumption.

  4. Modeling of in-vehicle magnetic refrigeration

    Olsen, Ulrik Lund; Bahl, Christian R.H.; Engelbrecht, Kurt

    2014-01-01

    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...

  5. Modeling of In-vehicle Magnetic refrigeration

    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...

  6. A versatile magnetic refrigeration test device

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

    2008-01-01

    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...... different parameter variations mentioned above. (C) 2008 American Institute of Physics....

  7. Basic dynamics of split Stirling refrigerators

    Waele, de A.T.A.M.; Liang, W.

    2008-01-01

    The basic features of the split Stirling refrigerator, driven by a linear compressor, are described. Friction of the compressor piston and of the regenerator, and the viscous losses due to the gas flow through the regenerator matrix are taken into account. The temp. at the cold end is an input

  8. New possibilities for non-CFC refrigeration

    Lorentzen, G.; Pettersen, J.

    1992-01-01

    There is a widespread belief that the only viable refrigerants in most applications are new fluorocarbon chemicals. This trend will eventually result in emissions of several hundred thousand tons of new chemicals to the atmosphere each year, involving potential risk of unforeseen environmental effects. A number of other options exist, or may be developed. By using substances which already have a natural role in our ecosystems, some uncertainty related to the critical issue of our future environment can be avoided. By development and practical testing of a laboratory prototype it has been documented that carbon dioxide is a viable refrigerant in automobile air conditioners, completely solving all environmental problems associated with such systems. General use of CO 2 as a refrigerant may provide a number of advantages in the present situation, both from an environmental and practical point of view. It is our considered opinion that the old carbon dioxide offers a key to the complete solution of the environmental problems in many areas of refrigeration usage. 19 refs., 8 figs., 5 tabs

  9. Nuclear heat sources for cryogenic refrigerator applications

    Raab, B.; Schock, A.; King, W.G.; Kline, T.; Russo, F.A.

    1975-01-01

    Spacecraft cryogenic refrigerators require thermal inputs on the order of 1000 W. First, the characteristics of solar-electric and radioisotope heat source systems for supplying this thermal input are compared. Then the design of a 238 Pu heat source for this application is described, and equipment for shipping and handling the heat source is discussed. (LCL)

  10. Modular Modeling of a Refrigeration Container

    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 t...

  11. Materials for room temperature magnetic refrigeration

    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)

  12. Air Conditioning and Refrigeration. Book One.

    Wantiez, Gary W.

    Designed to provide students with the basic skills for an occupation in air conditioning and refrigeration, this curriculum guide includes seven major areas, each consisting of one or more units of instruction. These areas and their respective units are titled as follows: Orientation (history and development, and job opportunities), Safety…

  13. Eco-Friendly Alternative Refrigeration Systems

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 10. Eco-Friendly Alternative Refrigeration Systems - Magnetic and ... Author Affiliations. S S Verma1. Deptartment of Physics, Sant Longowal Institute of Engineering and Technology Longowal, District Sangrur, Punjab 148 106, India.

  14. Detecting Fan Faults in refrigerated Cabinets

    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 discar...

  15. High performance magnetocaloric perovskites for magnetic refrigeration

    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...

  16. Hybrid control of the distributed refrigeration system

    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...

  17. The Absorption Refrigerator as a Thermal Transformer

    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.)

  18. The absoption refrigerator as a thermal transformer

    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.

  19. The absorption refrigerator as a thermal transformer

    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

  20. Online load forecasting for supermarket refrigeration

    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...

  1. Eco-Friendly Alternative Refrigeration Systems

    frigerants in mechanical refrigeration system has become a subject of great ..... In 1823, Seebeck discovered that a voltage drop appears across a junction (i.e., a .... delta function in the transport distribution centered about 2-3. KT from the ...

  2. Energy labelling of refrigerated display cases

    Sluis, S.M. van der

    1996-01-01

    Energy labelling of refrigerated display cabinets is a method to quickly assess the energy efficiency of a certain cabinet compared to the market average consumptions for similar cabinets. Labelling is also a method to obtain comparable data on cabinets from different manufacturers, which has time

  3. Analysis of refrigerant mal-distribution

    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...

  4. Energy consumption of small refrigerators - Information leaflet; Merkblatt Kleinkuehlschrank

    NONE

    2009-07-01

    In this leaflet published by the Swiss Federal Office of Energy (SFOE), the energy consumption of small refrigerators with a capacity of less than 100 litres is reported on. Such small refrigerators are often used in hotel rooms or in campers. It is noted that, in comparison, a typical, 150 litre class A++ domestic refrigerator uses only a fraction of the amount of energy used by such small refrigerators. The results of measurements made according to EN 153 and ISO 15502 norms are discussed. Recommendations are made on the purchase and operation of these small refrigerators.

  5. Applicability of ASST-A helium refrigeration system for JLab End Station Refrigerator

    Hasan, N.; Knudsen, P.; Ganni, V.

    2017-12-01

    The MØLLER experiment at Jefferson Lab (JLab) is a high power (5 kW) liquid hydrogen target scheduled to be operational in the 12 GeV-era. At present, cryogenic loads and targets at three of JLab’s four experimental halls are supported by the End Station Refrigerator (ESR) - a CTI/Helix 1.5 kW 4.5 K refrigerator. It is not capable of supporting the high power target load and a capacity upgrade of the ESR cryogenic system is essential. The ASST-A helium refrigeration system is a 4 kW 4.5 K refrigerator. It was designed and used for the Superconducting Super Collider Lab (SSCL) magnet string test and later obtained by JLab after the cancellation of that project. The modified ASST-A refrigeration system, which will be called ESR-II along with a support flow from JLab’s Central Helium Liquefier (CHL) is considered as an option for the End Station Refrigerator capacity upgrade. The applicability of this system for ESR-II under varying load conditions is investigated. The present paper outlines the findings of this process study.

  6. CFD Parametric Studies for Global Performance Improvement of Open Refrigerated Display Cabinets

    Pedro Dinis Gaspar

    2012-01-01

    Full Text Available A detailed CFD modelling of an open refrigerated display cabinet has been formulated in a previous study. Some modifications are introduced in order to perform parametric studies dealing with low-cost geometrical and functional characteristics for improvement of the global performance and energy efficiency. The parametric studies are devoted to the analysis of the thermal response and behaviour inside the food conservation space influenced by (1 air flow rate through the evaporator heat exchanger; (2 air curtain behaviour; (3 hole dimensions and distribution of the back panel; (4 discharge and return grilles angles; and (5 flow deflectors inside the internal duct. The analysis of the numerical predictions from the parametric studies allows the development of an optimized model for the conception of an open refrigerated display cabinet with a more adequate configuration. The numerical predictions of the optimized model show lower product temperature and reduced electrical energy consumption, allowing the improvement of the food safety and the energy rationalization of the refrigeration equipment.

  7. Paneling architectural freeform surfaces

    Eigensatz, Michael

    2010-07-26

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, socalled panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects. © 2010 ACM.

  8. Paneling architectural freeform surfaces

    Eigensatz, Michael

    2010-07-25

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, so-called panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects.

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

    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

  10. REINFORCED COMPOSITE PANEL

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  11. Data-Driven Predictive Direct Load Control of Refrigeration Systems

    Shafiei, Seyed Ehsan; Knudsen, Torben; Wisniewski, Rafal

    2015-01-01

    A predictive control using subspace identification is applied for the smart grid integration of refrigeration systems under a direct load control scheme. A realistic demand response scenario based on regulation of the electrical power consumption is considered. A receding horizon optimal control...... is proposed to fulfil two important objectives: to secure high coefficient of performance and to participate in power consumption management. Moreover, a new method for design of input signals for system identification is put forward. The control method is fully data driven without an explicit use of model...... against real data. The performance improvement results in a 22% reduction in the energy consumption. A comparative simulation is accomplished showing the superiority of the method over the existing approaches in terms of the load following performance....

  12. Solar reflection panels

    Diver, Jr., Richard B.; Grossman, James W [Albuquerque, NM; Reshetnik, Michael [Boulder, CO

    2006-07-18

    A solar collector comprising a glass mirror, and a composite panel, wherein the back of the mirror is affixed to a front surface of the composite panel. The composite panel comprises a front sheet affixed to a surface of a core material, preferably a core material comprising a honeycomb structure, and a back sheet affixed to an opposite surface of the core material. The invention may further comprise a sealing strip, preferably comprising EPDM, positioned between the glass mirror and the front surface of the composite panel. The invention also is of methods of making such solar collectors.

  13. Investigations of Heat Recovery in Different Refrigeration System Solutions in Supermarkets. Effsys2 project final report

    Sawalha, Same; Chen, Yang

    2010-07-01

    Supermarkets are intensive energy consumers with constantly increasing number of installations. About 50 % of the energy consumption in the supermarket is absorbed by the refrigeration system to cover the cooling demands. Simultaneously, heating is needed in the supermarket where the rejected heat from the refrigeration system is usually higher than the needs. It is an interesting possibility to utilize the rejected heat from the refrigeration system to cover the heating needs in supermarkets. The objective of this project is to investigate the heat recovery performance of the new refrigeration system solutions in supermarket applications. The focus is on environmentally friendly systems with natural working fluids, mainly CO{sub 2} trans-critical systems. The project analyzes the temperature levels and capacities of rejected heat from different system solutions and investigates its matching with the heating needs in supermarkets. Using simulation tools this project also aims at defining the system solution/s which has good energy efficiency for simultaneous cooling and heat recovery.

  14. Simulator of Cryogenic process and Refrigeration, and its Control in scientific -nuclear facilities with EcosimPro; Simulador de procesos criogenicos y de refrigeracion y de su control en las grandes instalaciones cienfificas nucleares con Ecosimpro

    Veleiro Blanco, A. M.

    2011-07-01

    The cryogenic plants and their control in Scientific-Nuclear Facilities is complicated by the large number of variables and the wide range of variation during operation. Initially the design and control of these systems in CERN was based on stationary calculations which non yielded the expected results. Due to its complexity, the dynamic simulation is the only way to get adequate results during operational transients.

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

    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. An optimized magnet for magnetic refrigeration

    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....

  17. A horizontal dilution refrigerator for polarized target

    Isagawa, S.; Ishimoto, S.; Masaike, A.; Morimoto, K.

    1978-01-01

    A horizontal dilution refrigerator was constructed with a view to the spin frozen target and the deuteron polarized target. High cooling power at high temperature such as 3.7 mW at 400 mK serves for overcoming a heat load of microwave to polarize the nuclear spins in the target material. The cooling power at 50 mK was 50 μW, which is sufficient to hold the high nuclear polarization for long time. The lowest temperature reached was 26 mK. The refrigerator has rather simple heat exchangers, a long stainless steel double tube heat exchanger and two coaxial type heat exchangers with sintered copper. The mixing chamber is made of polytetrafluoroethylene (TFE) and demountable so that the target material can be easily put into it. (Auth.)

  18. An optimized magnet for magnetic refrigeration

    Bjork, R.; Bahl, C.R.H.; Smith, A.; Christensen, D.V.; Pryds, N.

    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.

  19. The lifetime cost of a magnetic refrigerator

    Bjørk, Rasmus; Bahl, Christian R.H.; Nielsen, Kaspar Kirstein

    2016-01-01

    The total cost of a 25 W average load magnetic refrigerator using commercial grade Gd is calculated using a numerical model. The price of magnetocaloric material, magnet material and cost of operation are considered, and all influence the total cost. The lowest combined total cost with a device...... lifetime of 15 years is found to be in the range $150-$400 depending on the price of the magnetocaloric and magnet material. The cost of the magnet is largest, followed closely by the cost of operation, while the cost of the magnetocaloric material is almost negligible. For the lowest cost device...... characteristics are based on the performance of a conventional A+++ refrigeration unit. In a rough life time cost comparison between the AMR device and such a unit we find similar costs, the AMR being slightly cheaper, assuming the cost of the magnet can be recuperated at end of life....

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

    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.

  1. Stressed skin panels

    Anon

    2001-07-01

    Advantages and disadvantages of stressed skin panels, also known as structural insulated panels (SIPs), are discussed as material and labour-saving alternatives to traditional stick framing. Stressed skin panels are manufactured 'sandwich' assemblies with a rigid insulating polystyrene foam core, whose interior and exterior surfaces are bonded into panels. The skins distribute and carry the structural loading while the bonded foam core provides insulation and keeps the two skins aligned. Since there are fewer framing members, there is little thermal bridging and the R-value remains high. SIPs are usually manufactured in four feet by eight feet panels, although some manufacturers can produce panels up to eight feet by forty feet. SIPs are resource efficient as they use less wood than conventional framing (about 25 per cent less); can structurally cover large spans, requiring less supplementary framing. Use of SIPs eliminate the need for headers over small openings; provide the ability to nail anywhere; create less scrap and waste; lessen vulnerability to unfavourable weather and other job-site hazards, can reduce delays, and often can produce significant savings in material and labour costs. Limitations include the more complex approaches to plumbing and electrical systems, although this can be minimized by designers by incorporating much of the plumbing and electrical work on interior (non-panel) walls. Most stressed skin panels require one-half inch interior gypsum drywall. If become wet, stressed skin panels take a long time to dry out and may harbour mold growth. Larger stressed-skin panels used in floors and roofs, may require cranes or other machinery for handling because of their weight. Although not without some environmental impact, overall, stressed skin panels are judged to be a resource-efficient building technology with significant energy-efficiency benefits and distinct advantages over stick framing. 3 photos.

  2. Silicon spectrometer with a Peltier refrigerator

    Belcarz, E.; Chwaszczewska, J.; Hahn, G.; Nowicki, W.; Sawicka, B.; Skoczek, K.; Slapa, M.; Szymczak, M.

    1974-01-01

    This paper describes a spectrometer with a Si(Li) detector cooled by a Peltier refrigerator. The spectrometer is able to analyse samples of practically all most frequently encountered emitters of alpha, beta and low energy gamma radiation. The energy resolution were about 1.3-1.5 keV for 14 keV gamma radiation. The system can also operate in field conditions in the fluorescence analysis. (author)

  3. Cryo-refrigerators for CNS applications

    Clausen, J.; Lesser, J.; Sebastianutto, R.

    2001-01-01

    Cryo-refrigeration plants for cold neutron sources belong to the field of auxiliary plants or utility facilities of the reactor. In general, they are classified as non-nuclear and serve to dissipate the heat generated in the liquid hydrogen or deuterium from moderating the neutrons of the cold neutron source. Cryo-refrigeration plants for the temperature range of 20 K supply either refrigeration at constant temperature by means of evaporating the cryogenic coolant (usually hydrogen) or, as usual with cold sources, in a specific temperature range by means of warming-up the cryogenic coolant (usually helium) in the moderator or heat exchanger (condensation or subcooling of the deuterium). The operator's requirements to a refrigeration plant are, first of all, that the plant adjusts itself - at low-maintenance or maintenance-free - to the various operation modes at best thermodynamic efficiencies and that it offers as much operating convenience and operating safety as possible. Additional requirements are short times for cool-down, capacity adjustment, stand-by operation in order to avoid poisoning of the cold source and further operational requirements. However, these requirements are limited by mechanics, thermodynamics and financial means. For this reason, for each application a technical solution must be found which is optimally adapted to the competing requirements and which is based on a standard product of the manufacturer, if possible. The operator's different requirements have to be taken in account with regard to the design of the plant and choice of the components; economic aspects in addition also have to be considered. Wherever possible, proven standard components should be used. (orig.)

  4. Energy-optimal speed control of fans and compressor in a refrigeration system

    Jakobsen, Arne; Rasmussen, Bjarne D.

    1998-01-01

    Use of variable speed compressors and variable speed fans for both the evaporator and the condenser makes the refrigeration system more flexible, adds to the degree of freedom of the control system and therefore makes it possible to (on-line) optimise the various speeds involved. Say, for example...... and therefore the achievement of the potential for energy saving. This control/optimisation problem is investigated using a steady-state simulation model....

  5. Solar panel foundation device

    Hawley, W.W.

    1983-03-29

    A transportable solar panel foundation device which has a bottom member, at least one upstanding side member, and an essentially open top. The side members are angled to permit nesting of a plurality of the foundation devices, and reinforcement pads are carried by the foundation device to support legs for one or more solar panels.

  6. Panel 5: Microbiology and Immunology Panel

    Murphy, Timothy F.; Chonmaitree, Tasnee; Barenkamp, Stephen; Kyd, Jennelle; Nokso-Koivisto, Johanna; Patel, Janak A.; Heikkinen, Terho; Yamanaka, Noboru; Ogra, Pearay; Swords, W. Edward; Sih, Tania; Pettigrew, Melinda M.

    2014-01-01

    Objective The objective is to perform a comprehensive review of the literature from January 2007 through June 2011 on the virology, bacteriology, and immunology related to otitis media. Data Sources PubMed database of the National Library of Medicine. Review Methods Three subpanels with co-chairs comprising experts in the virology, bacteriology, and immunology of otitis media were formed. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a second draft was created. The entire panel met at the 10th International Symposium on Recent Advances in Otitis Media in June 2011 and discussed the review and refined the content further. A final draft was created, circulated, and approved by the panel. Conclusion Excellent progress has been made in the past 4 years in advancing an understanding of the microbiology and immunology of otitis media. Advances include laboratory-based basic studies, cell-based assays, work in animal models, and clinical studies. Implications for Practice The advances of the past 4 years formed the basis of a series of short-term and long-term research goals in an effort to guide the field. Accomplishing these goals will provide opportunities for the development of novel interventions, including new ways to better treat and prevent otitis media. PMID:23536533

  7. PVT Panels. Fully renewable and competitive

    Bakker, M.; Strootman, K.J.; Jong, M.J.M.

    2003-10-01

    A photovoltaic/thermal (PVT) panel is a combination of photovoltaic cells with a solar thermal collector, generating solar electricity and solar heat simultaneously. PVT panels generate more solar energy per unit surface area than a combination of separate PV panels and solar thermal collectors, and share the aesthetic advantage of PV. After several years of research, PVT panels have been developed into a product that is now ready for market introduction. One of the most promising system concepts, consisting of 25 m 2 of PVT panels and a ground coupled heat pump, has been simulated in TRNSYS, and has been found to be able to fully cover both the building related electricity and heat consumption, while keeping the long-term average ground temperature constant. The cost and payback time of such a system have been determined; it has been found that the payback time of this system is approximately two-thirds of the payback time of an identical system but with 21 m 2 of PV panels and 4 m 2 of solar thermal collectors. Finally, by looking at the expected growth in the PV and solar thermal collector market, the market potential for for PVT panels has been found to be very large

  8. RECIPANEL: RECYCLED PAPER PANELS

    HERNÁN CAÑOLA

    2012-01-01

    Full Text Available En este artículo se estudia la fabricación y el comportamiento mecánico de paneles a base de papel reciclado. El objetivo principal del proyecto es producir un prototipo de panel que emplee elementos provenientes de residuos sólidos (papel periódico y de un material conglomerante (cemento Portland blanco. El panel debe ser económico, debe tener buenas propiedades mecánicas y debe tener dimensiones comerciales para su uso en muros tabiques y en cielos falsos en la industria de la construcción. El Recipanel es un panel no estructural a base de papel reciclado. El Recipanel cumple las normas colombianas en lo relativo a los paneles de uso no estructural y presenta además unas excelentes características mecánicas.

  9. Puncture panel optimization

    Glass, R.E.; Longenbaugh, R.S.

    1986-01-01

    Sandia National Laboratories developed the TRansUranic PACkage Transporter (TRUPACT) to transport defense contact-handled transuranic wastes. The package has been designed to meet the normal and hypothetical accident conditions in 10CFR71 which includes the demonstrated ability to survive a 1-meter drop onto a mild steel pin. The puncture protection is provided by puncture resistant panels. In conjunction with the development of TRUPACT, a series of experiments has been conducted to reduce the weight of the puncture resistant panels. The initial scoping tests resulted in a preliminary design incorporating 30 layers of Kevlar. This design has been shown to meet the regulatory puncture test. To reduce the weight of this panel, subscale tests were conducted on panels utilizing Kevlar yarns with varying mass per unit length (denier) as well as different resins. This paper reviews the testing undertaken in the original panel development and discusses the results obtained from the recent subscale and full-scale optimization tests

  10. Solar panel cleaning robot

    Nalladhimmu, Pavan Kumar Reddy; Priyadarshini, S.

    2018-04-01

    As the demand of electricity is increasing, there is need to using the renewable sources to produce the energy at present of power shortage, the use of solar energy could be beneficial to great extent and easy to get the maximum efficiency. There is an urgent in improving the efficiency of solar power generation. Current solar panels setups take a major power loss when unwanted obstructions cover the surface of the panels. To make solar energy more efficiency of solar array systems must be maximized efficiency evaluation of PV panels, that has been discussed with particular attention to the presence of dust on the efficiency of the PV panels have been highlighted. This paper gives the how the solar panel cleaning system works and designing of the cleaning system.

  11. Analysis of cooldown performance for Isabelle helium refrigerator

    Wu, K.C.; Brown, D.P.; Moore, R.W.

    1982-01-01

    The cooldown performance for the ISABELLE Helium refrigerator is analyzed in terms of the relationship between refrigerator and its load. The flow diagram for ISABELLE with its redundant turbines and heat exchangers is given. Cycle description and procedure for cooldown is described with the relationship between a refrigerator and its load illustrated. Pressure vs. temperature for ISABELLE load and the efficiency for a turbine are illustrated. The procedure for modeling the refrigerator and the concepts of maximizing the cooldown capacity are described. The results and discussion are accompanied with T-S diagrams for initial stage of cooldown and refrigerator characteristic at various return temperatures. The ISABELLE refrigerator with its reduncant expanders properly used achieves cooldown capacity well beyond its steady-state capacity. The cooldown rate at this stage relies on the design safety margin, which for the ISABELLE is 50%

  12. Fault detection and diagnosis for refrigerator from compressor sensor

    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.

  13. Compatibility of refrigerants and lubricants with elastomers. Final report

    Hamed, G.R.; Seiple, R.H.; Taikum, Orawan

    1994-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. In part I of the program the swell behavior in the test fluids has been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed fro the refrigerant test fluids and 24 hours after removal from the lubricants. Part II of the testing program includes the evaluation of tensile strength, hardness, weight, and dimensional changes after immersion aging in refrigerant/lubricant mixtures of selected elastomer formulations at elevated temperature and pressure.

  14. Exergy analysis of refrigerators for large scale cooling systems

    Loehlein, K [Sulzer Cryogenics, Winterthur (Switzerland); Fukano, T [Nippon Sanso Corp., Kawasaki (Japan)

    1993-01-01

    Facilities with superconducting magnets require cooling capacity at different temperature levels and of different types (refrigeration or liquefaction). The bigger the demand for refrigeration, the more investment for improved efficiency of the refrigeration plant is justified and desired. Refrigeration cycles are built with discrete components like expansion turbines, cold compressors, etc. Therefore the exergetic efficiency for producing refrigeration on a distinct temperature level is significantly dependent on the 'thermodynamic arrangement' of these components. Among a variety of possibilities, limited by the range of applicability of the components, one has to choose the best design for higher efficiency on every level. Some influences are being quantified and aspects are given for a optimal integration of the refrigerator into the whole cooling system. (orig.).

  15. Thermoeconomic model of a commercial transcritical booster refrigeration system

    Ommen, Torben Schmidt; Elmegaard, Brian

    2011-01-01

    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...... of exergy for cooling. Second law analysis is needed to illustrate the characteristics of the plant at different load rates, according to the alternating load profile and corresponding to outdoor conditions. With the detailed model, different uses of the analysis are possible, including thermoeconomic...

  16. Performance measurement of a mini thermoacoustic refrigerator and associated drivers

    Petrina, Denys E.

    2002-01-01

    Approved for public release; distribution is unlimited A miniature Thermoacoustic refrigerator is being developed to cool integrated circuits - which must sometimes operate at high temperatures nearing the upper threshold of their tolerance - to temperature spans more within the circuits' tolerable limits, without the need of the chemicals of a traditional refrigerating system. The development of an electrically powered acoustic driver that powers the thermoacoustic refrigerator is describ...

  17. Research for Actively Reducing Infrared Radiation by Thermoelectric Refrigerator

    Kim, Hoon; Kim, Kyomin; Kim, Woochul [Yonsei Univ., Seoul (Korea, Republic of)

    2017-03-15

    We introduced a technology for reducing infrared radiation through the active cooling of hot surfaces by using a thermoelectric refrigerator. Certain surfaces were heated by aerodynamic heating, and the heat generation processes are proposed here. We calculated the temperatures and radiations from surfaces, while using thermoelectric refrigerators to cool the surfaces. The results showed that the contrast between the radiations of certain surfaces and the ambient environments can be removed using thermoelectric refrigerators.

  18. Hydrophilic structures for condensation management in refrigerator appliances

    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.

  19. Model based control of refrigeration systems

    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

  20. Refrigeration processes a practical handbook on the physical properties of refrigerants and their applications

    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

  1. Refrigeration Playbook. Heat Reclaim; Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation

    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.

  2. Reasearch and Evaluation of Electromagnetic Fields of Refrigerators

    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

  3. Control Methods for Energy Management of Refrigeration Systems

    Shafiei, Seyed Ehsan

    is decreased as the method does not need an explicit model of the system and, at the same time, the desired load following performance is attained. Recent research findings indicate that the refrigeration system commonly employed in food transportation can account for 40% of the total greenhouse gas emissions...... from the corresponding vehicle engines. Finally, the problem of optimization of a hybrid transport refrigeration system is addressed here. The hybrid refrigeration system is made by the integration of conventional refrigeration technology with thermal energy storage devices....

  4. Contribution to magnetic refrigeration study at liquid helium study

    Lacaze, A.

    1985-10-01

    An experimental prototype of magnetic refrigerator operates, following a Carnot cycle, with gallium gadolinium garnet, from liquid helium at 4.2 0 K. Analysis of the cyle and heat exchanges allowed to improve performance up to get more than 50% of Carnot yield at 1.8 0 K and nearly 80% at 2.1 0 K. Operation conditions of a regenerator refrigerator between 4 and 20 0 K are studied. The association of a magnetic refrigerator and a gas refrigerator is analyzed. Among different ways to realize the magnetic stage, an active regenerator cycle is chosen. An experimental device is described [fr

  5. Analysis of a combined Rankine-vapour-compression refrigeration cycle

    Aphornratana, Satha; Sriveerakul, Thanarath

    2010-01-01

    This paper describes a theoretical analysis of a heat-powered refrigeration cycle, a combined Rankine-vapour-compression refrigeration cycle. This refrigeration cycle combines an Organic Rankine Cycle and a vapour-compression cycle. The cycle can be powered by low grade thermal energy as low as 60 deg. C and can produce cooling temperature as low as -10 deg. C. In the analysis, two combined Rankine-vapour-compression refrigeration cycles were investigated: the system with R22 and the system with R134a. Calculated COP values between 0.1 and 0.6 of both the systems were found.

  6. Simulations

    Ngada, Narcisse

    2015-06-15

    The complexity and cost of building and running high-power electrical systems make the use of simulations unavoidable. The simulations available today provide great understanding about how systems really operate. This paper helps the reader to gain an insight into simulation in the field of power converters for particle accelerators. Starting with the definition and basic principles of simulation, two simulation types, as well as their leading tools, are presented: analog and numerical simulations. Some practical applications of each simulation type are also considered. The final conclusion then summarizes the main important items to keep in mind before opting for a simulation tool or before performing a simulation.

  7. Polyhalogenated hydrocarbon refrigerants and refrigerant oils colored with fluorescent dyes and method for their use as leak detectors

    Parekh, M.

    1988-07-19

    A leak detectable refrigeration composition is described comprising: (A) a refrigeration liquid selection from the group consisting of: (1) a polyhalogenated hydrocarbon refrigerant; (2) a refrigeration oil selected from the group consisting of naphthenic oils, paraffinic oils, alkylated benzenes, silicones, polyglycols, diesters or triesters of dicarboxylic or tricarboxylic acids, and polyalkyl silicate oils, and (3) a mixture of A(1) and A(2), and (B) a fluorescent dye compound or composition comprising the dye selected from the group consisting of: (1) a fluorescent dye selected from the group consisting of perylene, naphthoxanthene, monocyclic aromatic compounds having an organometallic compound, (2) a solution of fluorescent dye in a solvent, and (3) a mixture of B(1) and B(2). The fluorescent dye compound or composition is soluble in the refrigeration liquid. The concentration of the dye being at least 0.001 grams per 100 grams of the refrigeration liquid.

  8. Experimental Investigation of the Effect of Change in Ambient Air Temperature on Power Consumption of Domestic Refrigerators

    J. A. Olorunmaiye

    2012-12-01

    Full Text Available One of the manifestations of climate change is increase.in ambient air temperature usually referred to as global warming. For sustainable development in a country, there is need to identify impacts of climate change and the necessary adaptation and mitigation strategies to adopt. To simulate the effect of global warming on the power consumption of refrigerators, a (model No. 150 THERMOCOOL refrigerator filled with twenty-five 750cl packaged water bottleswas run in an air-conditioned room, in a room with the air-conditioner switched off and near an oven in a bakery. The electric power consumption of the refrigerator was measured using "Watts up?.net" Watt meter and the ambient temperature was measured using FLUKE temperature/humidity meter. The average hourly energy consumption of the refrigerator operating at mean ambient temperatures of 25.4°C, 30.7oC, 38.8°C were 93.844 Wh, 100.32 Wh and 105.08 Wh respectively. Some possible ways to reduce the increase in power consumption of refrigerators due to global warming include using compressors of higher efficiency and condensers of greater effectiveness.

  9. Predicting off-design range and performance of refrigeration cycle with two-stage centrifugal compressor and flash intercooler

    Turunen-Saaresti, Teemu; Roeyttae, Pekka; Honkatukia, Juha; Backman, Jari [Lappeenranta University of Technology, Institute of Energy Technology, Laboratory of Fluid Dynamics, P.O. Box 20, 53851 Lappeenranta (Finland)

    2010-09-15

    A modern refrigeration process requires constant control to provide required cooling for the user. To properly and economically accommodate this need, a wide operation range of the compressor is necessary. Therefore, it is of interest to investigate the off-design operation of a cooling cycle and compressor. The refrigeration cycle equipped with a two-stage centrifugal compressor and a flash intercooler is studied. The compressor operation maps are generated with two different design codes and the operation values of the compressors are interpolated from the compressor maps in the simulation of the entire cooling cycle. Based on the previous studies of the utilised refrigeration cycle, R245fa is selected as coolant. The aim of this study is to demonstrate the control capacity of the centrifugal compressor and the performance of the cooling loop in off-design conditions. This configuration provides better and wider control over the cooling range than the traditional on-off control of displacement compressors. (author)

  10. Refrigeration plants using carbon dioxide as refrigerant: measuring and modelling the solubility and diffusion of carbon dioxide in polymers used as sealing materials

    von Solms, Nicolas; Kristensen, Jakob

    2010-01-01

    Because of increased environmental pressure, there is currently a movement away from more traditional refrigerants such as HCFC's toward refrigerants with lower global warming potential such as carbon dioxide (CO2). However, the use of CO2 as a refrigerant requires a refrigeration cycle...

  11. Next Generation Refrigeration Lubricants for Low Global Warming Potential/Low Ozone Depleting Refrigeration and Air Conditioning Systems

    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.

  12. Cold distribution networks. Cold distribution by two-phase refrigerant fluid. Case of ice slurries; Reseaux de distribution de froid. Distribution de froid par fluide frigoporteur diphasique. Cas du coulis de glace stabilisee (2002 - 2004). Rapport final (1er juillet 2004). Programme energie. PRI 9.1

    Lallemand, A. [Institut National des Sciences Appliquees (INSA), Centre de Thermique de Lyon (CETHIL), UMR 5008, 69 - Villeurbanne (France); Mercier, P. [CEA Grenoble, Groupement pour la Recherche sur les Echangeurs Thermiques (GRETH), 38 (France); Royon, L. [Paris-1 Univ., Lab. de Biorheologie et d' Hydrodynamique Physico-Chimique, 75 (France); Dumas, J.P. [L' Ecole Nationale Superieure en Genie des Technologies Industrielles, Lab. de Thermique Energetique et Procedes, 64 - Pau (France); Guilpart, J. [URGPAN/CEMAGRE, 33 - Bordeaux (France)

    2004-07-01

    This PRI aims to participate to the development of alternate solutions for refrigerant fluids, for the cold transport and more specially a two phase refrigerant fluid: the stabilized ice slurry. The research program presented three main axis: design, realization and characterization of stabilized ice slurry, experimental studies of transport and transfer properties, study of online measurement process of the solid content. A simulation has been realized to evaluate the energy efficiency of this refrigerant use. (A.L.B.)

  13. A new modeling procedure for circuit design and performance prediction of evaporator coils using CO2 as refrigerant

    Larbi Bendaoud, Adlane; Ouzzane, Mohamed; Aidoun, Zine; Galanis, Nicolas

    2010-01-01

    The replacement of environmentally damaging synthetic refrigerants due to their ODP or GWI potential by natural refrigerants such as CO 2 is now up in the research agenda. Moreover, current energy supply concerns make of efficiency another first priority issue to dictate new stringent design criteria for industrial and commercial equipment. Heat exchangers are the most important components in refrigeration systems where they are used as evaporators or condensers and their design and operation have a considerable impact on overall system performance. Hence, it is important to better understand their thermal and hydrodynamic behaviour in order to improve their design and operation. Numerical simulation represents a very efficient tool for achieving this objective. In this paper, a new modeling approach, accounting for the heat transfer the hydrodynamics of the problem and intended to predict the dynamic behaviour of a refrigeration coil under dry conditions is proposed. A related FORTRAN program was developed, allowing the study of a large range of complex refrigerant circuit configurations. The equations describing these aspects are strongly coupled, and their decoupling is reached by using an original method of resolution. Circuits may have several inlets, outlets, bifurcations and feed one or several other tubes inlets. The coil was subdivided into several elementary control volumes and its analysis provided detailed information in X, Y and Z directions. Validation was performed with data from a CO 2 secondary refrigeration loop test bench built in CanmetENERGY Laboratories. These data were predicted satisfactorily over the operating range corresponding to refrigeration applications. Exemplary simulations were then performed on an evaporator typically employed in supermarkets, showing the effect of circuiting on operation and performance. Even though circuiting is common practice in refrigeration this simulation shows that care must be exercised in making the

  14. Study of change of refrigerant R{sub 2}2 in chiller units by simulation in EcosimPro; Estudio de cambio de gas refriferante R{sub 2}2 en unidades enfriadoras mediante simulacion en EcosimPro

    Prieto, J.; Molina, C.; Olmedo, J.; Gavilan, C. J.

    2014-07-01

    On January 1, 2010 is forbidden to hold any stock of virgin R{sub 2}2 refrigerant and it is also forbidden to use virgin R{sub 2}2 refrigerant for the service and maintenance of equipment under the new European Community Regulation 20137/2000. On January 1, 2015 and stock of R{sub 2}2, even if reclaimed or recycled, will be illegal to hold. In accordance with the European Community regulation, Cofrentes Nuclear Power Plant begins the R{sub 2}2 retrofit. (Author)

  15. FPGA Implementation of Multilayer Perceptron for Modeling of Photovoltaic panel

    Mekki, H.; Belhout, K.; Mellit, A.; Salhi, H.

    2008-01-01

    The Number of electronic applications using artificial neural network-based solutions has increased considerably in the last few years. However, their applications in photovoltaic systems are very limited. This paper introduces the preliminary result of the modeling and simulation of photovoltaic panel based on neural network and VHDL-language. In fact, an experimental database of meteorological data (irradiation, temperature) and output electrical generation signals of the PV-panel (current and voltage) has been used in this study. The inputs of the ANN-PV-panel are the daily total irradiation and mean average temperature while the outputs are the current and voltage generated from the panel. Firstly, a dataset of 4x364 have been used for training the network. Subsequently, the neural network (MLP) corresponding to PV-panel is simulated using VHDL language based on the saved weights and bias of the network. Simulation results of the trained MLP-PV panel based on Matlab and VHDL are presented. The proposed PV-panel model based ANN and VHDL permit to evaluate the performance PV-panel using only the environmental factors and involves less computational efforts, and it can be used for predicting the output electrical energy from the PV-panel

  16. TRNSYS simulation of a system consisted of PV panels and H{sub 2} production and storage to feed a remote telecom application (HIDROSOLARH{sub 2})

    Gomez, Guillermo; Martinez, Graciano; Maellas, Jesus; Cuevas, Raquel; Orihuela, Pilar [INTA, Torrejon de Ardoz (Spain). Renewable Energy Dept.; Bueno, Emilio; Gila, Raul [Alcala de Henares Univ. - Polytechnical School, Barcelona (Spain). Electronic Dept.

    2010-07-01

    Several forums have been created owing to the current worry about the climate change and find a safety energy source to study the best way to introduce the Hydrogen into the market. To get this purpose the fuel cells can be a good technology, but it is necessary find projects where the reliability is much important than the price. There are many projects where the advantages of fuel cells (noiseless, high density of energy, simplicity, portability,..) can be more important than the economic aspects, and so that the fuel cells can find a place in the market. An example of these projects can be the power system to feed remote telecom applications. The main target of this paper is to show the results of the TRNSYS simulation of HIDROSOLARH{sub 2} to determinate the most efficient configuration from the energy point of view and calculate the balance of plant (BOP). (orig.)

  17. Blue Ribbon Panel Report

    An NCI Cancer Currents blog by the NCI acting director thanking the cancer community for contributing to the Cancer Moonshot Blue Ribbon Panel report, which was presented to the National Cancer Advisory Board on September 7.

  18. Panel acoustic contribution analysis.

    Wu, Sean F; Natarajan, Logesh Kumar

    2013-02-01

    Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.

  19. Autoimmune liver disease panel

    Liver disease test panel - autoimmune ... Autoimmune disorders are a possible cause of liver disease. The most common of these diseases are autoimmune hepatitis and primary biliary cholangitis (formerly called primary biliary cirrhosis). This group of tests ...

  20. Advanced Ultrasupercritical (AUSC) Tube Membrane Panel Development

    Pschirer, James [Alstom Power Inc., Windsor, CT (United States); Burgess, Joshua [Alstom Power Inc., Windsor, CT (United States); Schrecengost, Robert [Alstom Power Inc., Windsor, CT (United States)

    2017-08-16

    membrane panels,and performed simulated shop repairs on the panel fabricated using Grade 92. GE executed the program as the prime contractor under the direction of Principal Investigator Mr. James Pschirer. Other participants in this project included GE Boiler Engineering, GE Chattanooga Manufacturing, GE Materials Technology Center, GE Rocky Mountain Service Center, and a Technical Consultant from Electric Power Research Institute (EPRI).