A Passive, Vapor Compression Refrigerator for Solar Cooling

1990 ◽  
Vol 112 (3) ◽  
pp. 191-195 ◽  
Author(s):  
R. I. Loehrke
Keyword(s):  
Heat Pipe ◽  
Waste Heat ◽  
Freezing Point ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Thermal Coefficient ◽  
Vapor Compression ◽  
Solar Cooling ◽  
Theoretical Considerations ◽  
Operating Temperature Range

A new, completely passive, vapor compression refrigerator is described in this paper. This refrigerator combines elements of the heat pipe and the vapor jet refrigerator and is referred to here as a heat pipe refrigerator. It may be driven with heat from low temperature solar collectors or with industrial waste heat and used to provide cooling. Compression work is provided by gas dynamic processes and liquid pumping may be obtained using gravitational or capillary forces. No power is required for operation. The device has no moving parts and may be externally similar to a heat pipe with three heat transfer zones. The working fluid is chosen to match the desired operating temperature range. Water, at subatmospheric pressure, is an appropriate fluid for operation around room temperature. Theoretical considerations indicate that the thermal coefficient of performance of the heat pipe refrigerator will depend strongly on the magnitude of the temperature differences over which it is designed to operate. Results from a laboratory test confirm the concept and demonstrate cooling down to the freezing point using water vapor at 51°C to drive the device and with heat rejection at 18°C.

Thermoelectric Heat Pipe-Based Refrigerator: System Development and Comparison with Thermoelectric, Absorption and Vapor Compression Refrigerators

2013 ◽  
Vol 651 ◽  
pp. 736-744
Author(s):  
Nandy Putra ◽  
H. Ardiyansya ◽  
Ridho Irwansyah ◽  
Wayan Nata Septiadi ◽  
A. Adiwinata ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Heat Dissipation ◽  
System Development ◽  
Coefficient Of Performance ◽  
Prototype System ◽  
Vapor Compression ◽  
Thermoelectric Coolers ◽  
Thermoelectric Systems ◽  
Vapor Compression System ◽  
Thermoelectric Heat

Thermoelectric coolers have been widely applied to provide cooling for refrigerators in addition to conventional absorption and vapor compression systems. To increase heat dissipation in the thermoelectric cooler’s modules, a heat pipe can be installed in the system. The aim of this study is to develop a thermoelectric heat pipe-based (THP) refrigerator, which consists of thermoelectric coolers that are connected by heat pipe modules to enhance heat transfer. A comparative analysis of the THP prototype and conventional refrigerator with vapor compression, absorption and thermoelectric systems is also presented. The prototype system has a faster cooling down time and a higher coefficient of performance than the absorption system but still lower than vapor compression system

Thermodynamic Analysis and Working Fluid Optimization of a Combined ORC-VCC System Using Waste Heat From a Marine Diesel Engine

2014 ◽  
Author(s):  
Oumayma Bounefour ◽  
Ahmed Ouadha
Keyword(s):  
Thermodynamic Analysis ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Vapor Compression ◽  
Marine Diesel ◽  
Vapor Compression Refrigeration ◽  
Propylene Yield ◽  
Fluid Optimization ◽  
Propane Butane

This paper examines through a thermodynamic analysis the feasibility of using waste heat from marine Diesel engines to drive a vapor compression refrigeration system. Several working fluids including propane, butane, isobutane and propylene are considered. Results showed that isobutane and Butane yield the highest performance, whereas propane and propylene yield negligible improvement compared to R134a for operating conditions considered.

A Hybrid Absorption System With Generator Level Optical Control and Variable Flow Rate

2019 ◽  
Author(s):  
Gleidson Souza ◽  
José V. C. Vargas ◽  
Wellington Balmant ◽  
Marcos C. Campos ◽  
Leonardo C. Martinez ◽  
...  
Keyword(s):  
Control System ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Air Conditioning ◽  
Energy Input ◽  
Waste Heat ◽  
Optical Control ◽  
Working Fluid ◽  
Vapor Compression ◽  
Regenerative Heat

Abstract Current refrigeration and air conditioning systems are mostly based on the vapor compression cycle, which require electrical energy input. Absorption systems have gained new interest due to the possibility of utilizing waste heat as energy input. In addition, the environmental impact generated by such systems is recognized as much smaller than vapor compression systems. Therefore, this work developed and characterized an absorption refrigeration system with an innovative generator level optical control and variable working fluid mass flow rate, with potential for use in industrial, commercial and residential heating, ventilation, air conditioning, and refrigeration (HVAC & R) systems. The system is hybrid, since it was designed to be fed with heat from the burning of different fuels and/or waste heat sources in complementary fashion. The system consists of: a condenser, an evaporator, two expansion valves, two absorbers, a centrifugal pump, a regenerative heat exchanger, a generator, a rectifier, a generator level optical control system, and two liquid accumulators. The developed level control system consists of 3 light Dependent Resistors (LDR) positioned inside a box built around a transparent level meter, and illuminated internally by a low power light bulb. A frequency inverter and a centrifugal pump allow for the working fluid solution inside the generator to be within a safe range for efficient cooling cycle operation. The system measured refrigeration capacity rate was 2.3 TR, which qualifies as a good performance, since the equipment was originally designed for 1 TR.

Design and Performance Analysis on CO2 Combined System in Supermarket

2012 ◽  
Vol 433-440 ◽  
pp. 1219-1225
Author(s):  
Jing Hong Ning ◽  
Sheng Chun Liu
Keyword(s):  
Energy Consumption ◽  
Waste Heat ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Space Heating ◽  
Combined System ◽  
Space Cooling ◽  
Gas Cooling ◽  
And Performance

This paper reports a combined space cooling, space heating, water heating and food refrigeration system (named CO2 combined system) in supermarket. This system using CO2 as the working fluid consists of a two-stage CO2 transcritical cycle used for food refrigeration, a single-stage CO2 transcritical cycle for space cooling in summer and space heating in winter. The waste heat emitted from the CO2 gas cooling in food refrigeration cycle and space cooling and space heating cycles is recovered by heat recover exchanger and is used to provide hot water for space heating and for general usage, such as the catering, the washing and the toilet facilities in the supermarket. So this CO2 combined system improves the coefficient of performance, decreases the energy consumption as well as reduces the heat pollution. Moreover, this CO2 combined system is compared with typical conventional supermarket technology, the results show that the energy consumption of CO2 combined system is reduced largely and energy efficiency is increased obviously. It can be concluded that the CO2 combined system has a good future for protecting environment and saving energy.

Gravity-Assisted Heat Pipe With Strong Marangoni Fluid for Waste Heat Management of Single and Dual-Junction Solar Cells

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Kenneth M. Armijo ◽  
Van P. Carey
Keyword(s):  
Heat Flux ◽  
Solar Cells ◽  
Heat Pipe ◽  
Waste Heat ◽  
Working Fluid ◽  
Water Mixture ◽  
Heat Management ◽  
Strong Concentration ◽  
Electrical Efficiency ◽  
Pipe System

This study investigates the cooling of single and multijunction solar cells with an inclined, gravity-assisted heat pipe, containing a 0.05 M 2-propanol/water mixture that exhibits strong concentration Marangoni effects. Heat pipe solar collector system thermal behavior was investigated theoretically and semi-empirically through experimentation of varying input heat loads from attached strip-heaters to simulate waste heat generation of single-junction monocrystalline silicon (Si), and dual-junction GaInP/GaAs photovoltaic (PV) solar cells. Several liquid charge ratios were investigated to determine an optimal working fluid volume that reduces the evaporator superheat while enhancing the vaporization transport heat flux. Results showed that a 45% liquid charge, with a critical heat flux of 114.8 W/cm2, was capable of achieving the lowest superheat levels, with a system inclination of 37 deg. Solar cell semiconductor theory was used to evaluate the effects of increasing temperature and solar concentration on cell performance. Results showed that a combined PV/heat pipe system had a 1.7% higher electrical efficiency, with a concentration ratio 132 suns higher than the stand-alone system. The dual-junction system also exhibited enhanced performance at elevated system temperatures with a 2.1% greater electrical efficiency, at an operational concentration level 560 suns higher than a stand-alone system.

A Study on the Combined Driven Refrigeration Cycle Using Ejector

2021 ◽  
pp. 2150004
Author(s):  
Waseem Raza ◽  
Gwang Soo Ko ◽  
Youn Cheol Park
Keyword(s):  
Air Conditioning ◽  
Waste Heat ◽  
Primary Source ◽  
Mechanical Efficiency ◽  
Coefficient Of Performance ◽  
Cycle Performance ◽  
Working Fluid ◽  
Low Grade ◽  
Refrigeration Cycle ◽  
R 134A

The rising need for thermal comfort has resulted in a rapid increase in refrigeration systems’ usage and, subsequently, the need for electricity for air-conditioning systems. The ejector system can be driven by a free or affordable low-temperature heat source such as waste heat as the primary source of energy instead of electricity. Heat-driven ejector refrigeration systems become a promising solution for reducing energy consumption to conventional compressor-based refrigeration technologies. An air-conditioning system that uses the ejector achieves better performance in terms of energy-saving. This paper presents a study on the combined driven refrigeration cycle based on ejectors to maximize cycle performance. The experimental setup is designed to determine the coefficient of performance (COP) with ejector nozzle sizes 1.8, 3.6, and 5.4[Formula: see text]mm, respectively. In this system, the R-134a refrigerant is considered as a working fluid. The results depict that the efficiency is higher than that of the conventional refrigeration method due to comparing the performance of the conventional refrigeration cycle and the combined driven refrigeration cycle. The modified cycle efficiency is better than the vapor compression cycle below 0∘C, which implies sustainability at low temperatures by using low-grade thermal energy. For the improvement of mechanical efficiency, proposed cycle can be easily used.

Waste-Heat Driven Miniature Absorption Refrigeration System Using Ionic-Liquid as a Working Fluid

2011 ◽  
Author(s):  
Yoon Jo Kim ◽  
Sarah Kim ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov ◽  
Paul A. Kohl
Keyword(s):  
Ionic Liquid ◽  
Waste Heat ◽  
Coefficient Of Performance ◽  
System Level ◽  
Working Fluid ◽  
Operating Efficiency ◽  
Outlet Temperature ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Absorption Refrigeration System

An ionic-liquid (IL) is a salt in a liquid state usually with an organic cation and inorganic anion. ILs provide an alternative to the normally toxic working fluids in absorption systems, such as the ammonia/water system. They also eliminate the problems of poor temperature match, crystallization and metal-compatibility problems of the water/LiBr system. In the present study, an IL is explored the working fluid of a miniature absorption refrigeration system so as to utilize waste-heat within the system for low-cost, high-power electronics cooling. To determine performance benchmarks for the refrigerant/IL (e.g. [bmim][PF6]) pairs, system-level simulations have been carried out. An NRTL model was built and used to predict the solubility of the mixture as well as the mixture properties such as enthalpy and entropy. The properties of the refrigerants were determined using REFPROP 6.0. Saturation temperatures at the evaporator and condenser were 25°C and 50°C, respectively. Chip power was fixed at 100 W with the operating temperature set at 85°C. R32 gave the highest operating efficiency with the maximum coefficient of performance (COP) of ca. 0.55 while R134a and R152a showed comparable performance with the maximum COP of ca. 0.4 at the desorber outlet temperature of 80°C. When waste-heat is available for the system operation, R134a and R152a COPs were comparable or better than that of R32.

scholarly journals Improvement of Heat Pipe Solar Collector Thermal Efficiency Using Al2O3/Water and TiO2/Water Nanofluids

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sinan Ünvar ◽  
Tayfun Menlik ◽  
Adnan Sözen ◽  
Hafız Muhammad Ali
Keyword(s):  
Heat Pipe ◽  
Heat Exchangers ◽  
Base Fluid ◽  
Operating Temperature ◽  
Pure Water ◽  
Heat Pipes ◽  
Working Fluid ◽  
Solar Collectors ◽  
Instantaneous Power ◽  
Operating Temperature Range

Heat pipe solar collectors (HPSCs) are heat exchangers that carry heat based on the phase change of the heat pipe working fluid. It is aimed to increase the operating temperature range of solar collectors by changing the phase of the working fluid in the heat pipe at low temperature. For this reason, it has become widespread to use nanofluids obtained by mixing nanosized metal oxides with the base fluid in certain proportions in order to increase both the thermal conductivity of the heat pipe working fluids and to increase the specific heat closures. The main purpose of this study, which was conducted to evaluate the performance of HPSCs, is to increase performance, and an experimental study has been conducted in this direction. For this purpose, an HPSC designed and manufactured was used. Al2O3-water and TiO2-water nanofluids containing 2% nanoparticles were used in order to increase performance in the study. HPSC used in the study consists of 8 heat pipes with a length of 100 cm. The experiments were carried out for pure water and nanofluids, and their efficiency and strength were compared. The highest value of instantaneous efficiency was calculated as 48% when pure water was used as the working fluid, 58% for Al2O3-water nanofluid, and 64% for TiO2-water nanofluid. The instantaneous power obtained using pure water was determined as 135.66 W, 167.96 W for Al2O3-water nanofluid, and 184.03 W for TiO2-water nanofluid. The improvement in efficiency was determined as 20.8% for Al2O3-water nanofluid and 33.3% for TiO2-water nanofluid. Improvement in powers was found to be 23.8% for Al2O3-water nanofluid and 35.6% for TiO2-water nanofluid.

scholarly journals Investigation of Loop Heat Pipe Survival and Restart After Extreme Cold Environment Exposure

2009 ◽  
Author(s):  
Eric Golliher ◽  
Jentung Ku ◽  
Anthony Licari ◽  
James Sanzi
Keyword(s):  
Heat Pipe ◽  
Freezing Point ◽  
Thermal Control ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
The Moon ◽  
Novel Approach ◽  
Condenser Temperature ◽  
Extreme Cold ◽  
Compensation Chamber

NASA plans human exploration near the South Pole of the Moon, and other locations where the environment is extremely cold. This paper reports on the heat transfer performance of a loop heat pipe exposed to extreme cold under the simulated reduced gravitational environment of the Moon. A common method of spacecraft thermal control is to use a loop heat pipe with ammonia working fluid. Typically, a small amount of heat is provided either by electrical heaters or by environmental design, such that the loop heat pipe condenser temperature never drops below the freezing point of ammonia. The concern is that a liquid-filled, frozen condenser would not re-start, or that a thawing condenser would damage the tubing due to the expansion of ammonia upon thawing. This paper reports the results of an experimental investigation of a novel approach to avoid these problems. The loop heat pipe compensation chamber is conditioned such that all the ammonia liquid is removed from the condenser and the loop heat pipe is non-operating. The condenser temperature is then reduced to below that of the ammonia freezing point. The loop heat pipe is then successfully re-started.

An Investigation of Water as a Refrigerant

1993 ◽  
Vol 115 (4) ◽  
pp. 257-263 ◽  
Author(s):  
D. Van Orshoven ◽  
S. A. Klein ◽  
W. A. Beckman
Keyword(s):  
Energy Savings ◽  
Freezing Point ◽  
Volume Flow ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Vapor Compression ◽  
New Type ◽  
Vapor Compression Refrigeration ◽  
Ice Production ◽  
Technical Considerations

This paper explores some of the basic thermodynamic and technical considerations involved in using water as a working fluid for refrigeration and heat pump cycles down to its freezing point of 0°C. It is first shown how the integration of the functions of refrigerant and heat transfer fluid can lead to energy savings, especially for the case of ice production. Next, the two fundamental requirements that the compressor must fulfill—handling a very large volume flow and achieving a large compression ratio—are described. A thermodynamic analysis of multistage compression follows to investigate the adiabatic head requirements and the large desuperheating irreversibility. It is concluded that a radically new type of vacuum compressor must be developed in order for water to be used as working fluid in vapor compression refrigeration cycles.

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