Mathematical Simulation of a Solar Bi-Ejector Refrigeration System

Solar Energy ◽  
2006 ◽  
Author(s):  
Bo Zhang ◽  
Jianhua Dong ◽  
Shengqiang Shen
Keyword(s):  
Thermal Behavior ◽  
Mathematical Simulation ◽  
Heat Load ◽  
Cooling Water ◽  
Electricity Consumption ◽  
Working Fluid ◽  
Cooling Load ◽  
Refrigeration System ◽  
Simulation Results ◽  
Mechanical Circulation

This paper presents a mathematical simulation of the dynamic thermal behavior of an innovative solar bi-ejector refrigeration system with a capacity to produce cooling water. In the bi-ejector refrigeration system, the mechanical circulation pump is replaced by a vapor-liquid ejector, in order to further reduce the electricity consumption and reinforce the system feasibility. Freon R123 is the working fluid at condensing temperature of 30°C generating temperature of 85°C and evaporating temperature of 8°C The generator heat load is 10kW and an obtained evaporator cooling load is around 3kW. The whole year simulation results are presented.

Visualization and Evaporation Resistance Measurement for Groove-Wicked Flat Plate Heat Pipes

2011 ◽  
Author(s):  
Shwin-Chung Wong ◽  
Chung-Wei Chen
Keyword(s):  
Flat Plate ◽  
Heat Load ◽  
Cooling Water ◽  
Base Plate ◽  
Heat Pipes ◽  
Working Fluid ◽  
Plate Temperature ◽  
Plate Heat ◽  
Heated Zone ◽  
Liquid Front

This work experimentally studied the evaporation characteristics in groove-wicked flat-plate heat pipes. The parallel, U-shaped grooves have a width of 0.25 mm and a depth of 0.16 mm. Uniform heating was applied to the copper base plate near one end, and a cooling water jacket was connected at the other end. The evaporation resistance was calculated based on the difference of the plate temperature and the vapor temperature respectively under and above the center of the heated zone. Water was used as the working fluid. With stepwise increase of heat load, the behavior of the working fluid in the grooves was visualized, and the evaporation resistances were measured. Above a certain heat load, longitudinal liquid recession can be visualized with a steep-sloped liquid front. Behind the short liquid front is the accommodation region where the meniscus appeared to anchor on the top corners of the groove walls. Under a thermally stable situation, longitudinal oscillations of the liquid front existed in many grooves. Also, the liquid motion in different grooves seemed independent, forming a constantly varying zigzag front line. With increasing heat load, the liquid fronts gradually left the heated zone, accompanied by increasing plate temperatures. The evaporation resistance data appeared larger and more scattered than those associated with mesh or powder wicks in our published experiments, presumably due to the relatively large groove size and surface roughness from etching. No boiling was observed in all present tests. The evaporation resistances for groove wicks increase monotonically in response to the gradually enlarged dryout region with increasing heat load.

High Performance Loop Heat Pipe With Flat Evaporator for Energy-Saving Cooling Systems of Supercomputers

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Zhi Hu Xue ◽  
Wei Qu ◽  
Ming Hui Xie
Keyword(s):  
Heat Load ◽  
High Performance ◽  
Operating Temperature ◽  
Cooling Water ◽  
Working Fluid ◽  
Air Cooling ◽  
Water Cooling ◽  
Test Results ◽  
Central Processing ◽  
Flat Evaporator

Abstract Two high performance loop heat pipes (LHPs) are developed for direct cooling of the chips in supercomputer. The two LHPs using flat evaporator are: one called water-cooling LHP and another one called air-cooling LHP. The working fluid of LHP is ammonia. The water-cooling LHP can work well at a heat load up to 663 W and air-cooling LHP can work well at a heat load up to 513 W. The two LHPs applying to the real computer servers are realized and tested. The server test results with water-cooling LHP have shown that the operating temperature of central processing units (CPUs) can be controlled to about 67 °C to ensure the reliable operating and acceptable level for electronic chips, even at condenser-cooling water temperature of 40 °C with low water flowrate of 0.055 m3/h. The server test results with air-cooling LHP have shown that the operating temperature of CPUs can be controlled to about 51 °C even at condenser-cooling wind temperature of 30 °C with wind flowrate of 41.88 m3/h.

Dynamic Characteristics of the Capillary Pumped Loop for Cooling the Tower-Type Computer

2007 ◽  
Author(s):  
Atsushi Tsujimori ◽  
Masashi Kato ◽  
Maiko Uchida
Keyword(s):  
Heat Flux ◽  
Heat Transport ◽  
Dynamic Characteristics ◽  
Heat Load ◽  
Cooling Water ◽  
Transport Rate ◽  
Working Fluid ◽  
High Heat Flux ◽  
Capillary Pumped Loop ◽  
Heat Loads

Capillary pumped loop has been widely investigated for space thermal control devices. This cooling device with high reliability and thermal controllability is also considered to be suited to cool electronic devices like personal computers. Because the capillary pumped loop is good at absorbing heat from high heat flux region like micro-processors, transporting it and releasing it from the large surface for packaging. In this research, the experimental equipment of the capillary pumped loop was manufactured. The experimental apparatus consists of the evaporator, the condenser, the liquid line, the vapor line and the reservoir. In the experiments heat load is applied to the evaporator by a resistance heater. And heat is released from the condenser to the cooling water which is set to be a constant temperature by the refrigerator. The length and the diameter of the evaporator are 150mm and 27mm respectively and the capillary wick with equivalent diameter of 5μm is embedded in the evaporator. These specifications were designed to give 2500mm heat transport distance and to adapt the natural convection heat transfer to the ambient without a cooling fan. As is proposed in the recent study, the inside of the capillary wick was used as the reservoir to simplify the loop. In our previous study, the heat transport characteristics in steady states were investigated when the heat flux, the cooling water temperature and the evaporator height above the condenser changed, and then the effects of enclosed rate of the working fluid in the reservoir and the inclination angles of the evaporator on heat transport rate were investigated. The computer code was also developed to simulate the heat transport characteristics and evaluate the maximum heat transport rate of the tested capillary pump. In the next step, we focus on the dynamic characteristics. The heat loads of the micro-processors in the computers usually change according to the working conditions of the application software and vary hourly. Thus the active thermal regulation accompanied with the change of heat loads is the important factor for cooling devices in the computers. So in this study the heat transport characteristics in the dynamic conditions of the capillary pumped loop were investigated. In the experiment, the start-up and shut-down mode at a given heat load were tested at first. Then heat load were changed in incremental or decremental steps from 30 to 70W. All results show the good thermal controllability.

Investigation of Engine Waste Heat Recovery Using Supercritical CO2(S-CO2) Cycle System

2018 ◽  
Author(s):  
Jian Song ◽  
Xiao-dong Ren ◽  
Chun-wei Gu
Keyword(s):  
Low Temperature ◽  
Heat Load ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cooling Water ◽  
Working Fluid ◽  
Exhaust Gas ◽  
Engine Exhaust ◽  
Cycle System

Primary energy consumption of diesel engines is increasing rapidly and strict emission standards are introduced by the government. Interests in engine waste heat recovery have been renewed to alleviate the energy shortage and emission issues. Supercritical CO2 (S-CO2) cycle has emerged as a promising method considering its compact structure and system safety level in addition to the environmental friendly characteristics. This paper explores the potential of using S-CO2 cycle system for engine waste heat recovery. Both heat load from the low temperature jacket cooling water and the high temperature engine exhaust gas are intended to be recovered. In the original system, the jacket cooling water is used to preheat the S-CO2 working fluid and the engine exhaust gas is utilized in the preheater. As an optimized scheme, system with two preheaters is presented. The engine exhaust gas is further cooled in a high temperature preheater after the jacket cooling water in the low temperature preheater. The available heat load from these two heat sources can be entirely recovered. However, the increasing preheating temperature suppresses the regeneration effect. A regeneration branch is then added in the system. Part of the S-CO2 working fluid from the compressor goes into a low temperature regenerator and then converges with the other part from the two preheats. A deeper utilization of the regeneration heat load is achieved and performance enhancement of the S-CO2 cycle system is expected. The maximum net power output of the system with regeneration branch reaches 82.8 kW, which results in an 8.5% increment on the engine power output.

Simulation and Productive Practice of 60 Tons Huge Rectangular Ingot by Wind Cooling

2011 ◽  
Vol 233-235 ◽  
pp. 2714-2717
Author(s):  
Xin Gang Ai ◽  
Sheng Li Li ◽  
Dong Wei Zhang ◽  
Nan Lv ◽  
Jun Tao
Keyword(s):  
Mathematical Simulation ◽  
Surface Quality ◽  
Solidification Time ◽  
Special Method ◽  
Cooling Process ◽  
Heavy Plate ◽  
Simulation Results

Huge rectangular ingots becomes crying needs in the condition of lots of heavy plate mills more than 5m have been in operation. In this paper, a special method of wind cooling outside mould has been presented and applied to produce 60t rectangular ingot. Mathematical simulation results tell us that by wind cooling, the solidification time of the 60t ingot can be shortened by 67 minutes, internal soundness can be ensured. The wind cooling process can obviously improve microstructure and preventing skull patch by increasing the thickness of solidified shell. A 60 tons huge rectangular ingot is successfully produced by wind cooling, the surface quality of is very well and the internal soundness should be improved further.

Thermal Response and Ablation Research of EPDM Thermal Protection Material in Ramjet

2015 ◽  
Vol 1092-1093 ◽  
pp. 534-538
Author(s):  
Xiong Chen ◽  
Hai Feng Xue ◽  
Hua Liang
Keyword(s):  
Heat Transfer ◽  
Heat Load ◽  
Thermal Protection ◽  
Thermal Response ◽  
Transfer Model ◽  
Back Face ◽  
Ground Test ◽  
Simulation Results ◽  
Face Temperature ◽  
Scanning Electron

Thermal protection materials are required to preserve the metal components of motor that suffer severe heat load. The research on thermal response of insulation of ramjet combustion chamber was carried out by the ground test and numerical simulation. During the working time of the ramjet, the back-face temperature of the thermal protection material was measured. The scanning electron microscope of samples was investigated. The calculation of thermo-chemical flow was solved by the CFD software FLUENT to provide the heat load boundary for simulation of heat transfer of EPDM insulation. The heat transfer model was solved by the FEA software ANSYS. Comparison of the temperature profile at the ablating surface between calculation and measurement shows the two results agree with each other. The simulation results can provide the temperature rising trend of insulation in a certain extent.

Design of a Solar Assisted Absorption Refrigeration System

2014 ◽  
Vol 953-954 ◽  
pp. 66-73
Author(s):  
Yan Ling Liu ◽  
Xue Zeng Shi ◽  
Yuan Yu
Keyword(s):  
High Pressure ◽  
Solar Energy ◽  
System Simulation ◽  
Double Effect ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Absorption System ◽  
Pressure Generator ◽  
Simulation Results ◽  
Absorption Refrigeration System

This paper presents the design of a solar/gas driving double effect LiBr-H2O absorption system. In order to use solar energy more efficiently, a new kind of solar/gas driving double effect LiBr-H2O absorption system is designed. In this system, the high-pressure generator is driven by conventional energy, natural gas, and solar energy together with water vapor generated in the high-pressure generator, which supplies energy to the low-pressure generator for a double effect absorption system. Simulation results illustrate that this kind of system is feasible and economical. Economic evaluation of several systems is also given in this paper in order to get a clear knowledge of the energy consumption of the system.

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