scholarly journals Experimental and Theoretical Study on the Cooling Performance of a CO2 Mobile Air Conditioning System

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1927 ◽  
Author(s):  
Dandong Wang ◽  
Binbin Yu ◽  
Junye Shi ◽  
Jiangping Chen
Keyword(s):  
Air Conditioning ◽  
Theoretical Study ◽  
Cooling Capacity ◽  
Air Conditioning System ◽  
Cooling Performance ◽  
System A ◽  
Hfc 134A ◽  
Expansion Valve ◽  
The Impact ◽  
Compressor Efficiency

CO2 (GWP = 1) is considered as a promising natural alternative refrigerant to HFC-134a in mobile air conditioning (MAC) applications. The objective of this study is to investigate the cooling performance characteristics of a CO2 MAC system. A prototype CO2 MAC system, consisting of a CO2 electrical compressor, CO2 parallel flow microchannel heat exchangers, and an electrical expansion valve, was developed and tested. Factor analysis experiments were conducted to reveal the effect of outdoor temperature on the cooling performance of this CO2 MAC system. Compared with a conventional R134a MAC system, the prototype CO2 MAC system achieved comparable cooling capacity, but had COP reductions of 26% and 10% at 27 °C and 45 °C outdoor conditions, respectively. In addition, based on refrigerant properties, theoretical cycle analysis was done to reveal the impact of evaporator, gas cooler and compressor, on the system cooling performance. It is concluded that the increase of overall compressor efficiency or the decrease of gas cooler approaching temperature could greatly improve the COP of this CO2 MAC system.

Rechargeable Personal Air Conditioning Device

2016 ◽  
Author(s):  
Yilin Du ◽  
Jan Muehlbauer ◽  
Jiazhen Ling ◽  
Vikrant Aute ◽  
Yunho Hwang ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Cooling System ◽  
Cooling Capacity ◽  
Comfort Level ◽  
Vapor Compression ◽  
Air Conditioning System ◽  
System A ◽  
Single Person ◽  
Vapor Compression Cycle ◽  
Compression Cycle

A rechargeable personal air-conditioning (RPAC) device was developed to provide an improved thermal comfort level for individuals in inadequately cooled environments. This device is a battery powered air-conditioning system with the phase change material (PCM) for heat storage. The condenser heat is stored in the PCM during the cooling operation and is discharged while the battery is charged by using the vapor compression cycle as a thermosiphon loop. The conditioned air is discharged towards a single person through adjustable nozzle. The main focus of the current research was on the development of the cooling system. A 100 W cooling capacity prototype was designed, built, and tested. The cooling capacity of the vapor compression cycle measured was 165.6 W. The PCM was recharged in nearly 8 hours under thermosiphon mode. When this device is used in the controlled built environment, the thermostat setting can be increased so that building air conditioning energy can be saved by about 5–10%.

Experimental analysis of the low-GWP refrigerant R1234yf as a drop-in replacement for R134a in a typical mobile air conditioning system

2012 ◽  
Vol 226 (11) ◽  
pp. 2713-2725 ◽  
Author(s):  
Yu Zhao ◽  
Zhaogang Qi ◽  
Jiangping Chen ◽  
Baixing Xu ◽  
Bin He
Keyword(s):  
Working Conditions ◽  
Air Conditioning ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Laminated Plate ◽  
Improve Performance ◽  
Air Conditioning System ◽  
Expansion Valve ◽  
Variable Displacement ◽  
Valve Opening

This study investigated the performance of a typical mobile air conditioning system using R134a and R1234yf as the working fluids under different working conditions. The system is composed of a microchannel parallel flow condenser, a laminated plate evaporator, a variable displacement compressor, and a thermal expansion valve. The different working cycles of each refrigerant were comprehensively compared. The optimum refrigerant charge amount of the R1234yf system was approximately 95% of the R134a system during drop-in tests. The performance of the R134a system was a little higher than that of the R1234yf system. The cooling capacity and system coefficient of performance of the R134a system were 12.4% and 9% larger, respectively. This result is mainly because of the thermophysical property differences between the two refrigerants and the improper expansion valve opening of R1234yf. Analysis on the whole cycle revealed that the R1234yf system could obtain a higher evaporating pressure and a larger superheat and subcooling. Redesigning the expansion valve for R1234yf could improve performance of the system.

Performance of Automotive Air-Conditioning System by Using Ejector as an Expansion Device

2016 ◽  
Vol 819 ◽  
pp. 216-220
Author(s):  
Firdaus Mat Jusoh ◽  
Henry Nasution ◽  
Azhar Abdul Aziz ◽  
Sumeru ◽  
Afiq Aiman Dahlan ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Internal Heat ◽  
Experimental Period ◽  
Cooling Capacity ◽  
Time Interval ◽  
Expansion Process ◽  
Air Conditioning System ◽  
Automotive Air Conditioning ◽  
Expansion Valve ◽  
Automotive Air Conditioning System

An automotive air conditioning system that uses thermal expansion valve (TEV) as an expansion device. The pressure drop from the condenser and evaporator pressure is considered an isenthalpic process (constant enthalpy), where this process causes energy loss (entropy generation) in the expansion process. The ejector recovers energy losses, which was previously lost in the expansion valve, and an ejector can be used to generate isentropic condition in the expansion process. The use of an ejector as an expansion device in this study can reduce power consumption of the compressor and increase cooling capacity of the evaporator. The experiments were conducted with temperature set-points of the conditioned space of 21, 22 and 23°C with internal heat loads of 100, 200 and 400 W. Measurements were taken during the one hour experimental period at a time interval of five minutes. The experiment results indicate that the ejector system is better than TEV and save fuel.

scholarly journals Performance assessment of alternate refrigerants for retrofitting R22 based air conditioning system

2018 ◽  
Vol 22 (2) ◽  
pp. 931-941 ◽  
Author(s):  
Mian Saeed ◽  
Shafiq Qureshi ◽  
Khurram Hashmi ◽  
Muhammad Khan ◽  
Syed Danish
Keyword(s):  
Ozone Depletion ◽  
Air Conditioning ◽  
Cooling Capacity ◽  
Air Conditioning System ◽  
Suitable Alternative ◽  
Energy And Exergy ◽  
Expansion Valve ◽  
Exergy Performance ◽  
Lower Discharge ◽  
Ozone Depletion Potential

The performance of zero ozone depletion potential refrigerants is investigated when retrofitted in R22 based air conditioning system. The options evaluated are R407C, R417A, R422D, R427A, and R438A. In order to arrive at most suitable alternative(s) to R22, energy and exergy performance of candidate refrigerants is carried out and compared against that of R22. The COP and exergy efficiencies showed that none of selected refrigerant is as efficient as R22 however their values suggests that each may be considered as potential substitute for retrofitting. Having comparable COP to others but low cooling capacity of R417A makes it less attractive. With comparatively reduced COP, lowest exergy efficiency and highest mass-flow rate, makes R422D the least desirable option. The R407C, R427A, and R438A emerged as most attractive substitutes. The lower discharge temperatures of substitutes will enhance the compressor life. Further, for substitutes there may be a possible change out of expansion valve.

Theoretical and experimental simulation of roof-top bus multiple-circuit air-conditioning system performance

2007 ◽  
Vol 221 (12) ◽  
pp. 1665-1677
Author(s):  
M Khamis Mansour ◽  
M N Musa ◽  
M N W Hassan ◽  
H Abdullah
Keyword(s):  
Experimental Data ◽  
Computer Model ◽  
Air Conditioning ◽  
Cooling Capacity ◽  
Experimental Simulation ◽  
Cooling Load ◽  
Air Conditioner ◽  
Air Conditioning System ◽  
System A ◽  
Cooling Loads

Many air-conditioning (AC) systems are designed to operate at maximum cooling capacity regardless of the variation in the daily cooling load. At low loads, the conditions can be uncomfortably cold and the overcooling is an unnecessary waste of energy. To address these two issues, a multiple refrigeration circuit concept is proposed and applied to a roof-top bus AC system. A two-circuit model is proposed for a standard bus size in which each circuit has two evaporators of equal sizes arranged in parallel and installed on each passenger row, respectively. This means that each passenger row is served by two different evaporators sharing a common heat exchanger box. Depending on the cooling load, this concept allows one or both circuits (compressor motors) to be switched on and during either modes, it also allows one or more sets of evaporator blowers to be switched on. A steady-state computer model has been developed to simulate the performance of the proposed two-circuit AC system. A two-circuit air conditioner is also designed to form a roof-top bus AC system, fabricated, and installed on to an experimental rig. The experimental data are used to validate the computer model. The validation is on the system thermal performance and on the evaporator air outlet conditions (dry bulb temperature and relative humidity) at different modes of system operation, either at full or partial cooling loads. The simulated results gave satisfactory agreement with those obtained from the experimental work. Maximum absolute deviations are within the range of 19.3 per cent, although most of the simulated results are less than a 10 per cent range from the experimental ones, which validates the computer program. The paper describes the modelling work carried out and the results obtained are presented in comparison with the experimental data.

Experimental studies on the performance of mobile air conditioning system using environmental friendly HFO-1234yf as a refrigerant

2019 ◽  
pp. 095440891988123 ◽  
Author(s):  
Prabakaran Rajendran ◽  
Shaji Sidney ◽  
Iyyappan Ramakrishnan ◽  
Mohan Lal Dhasan
Keyword(s):  
Heat Exchanger ◽  
Air Conditioning ◽  
Exergy Analysis ◽  
Coefficient Of Performance ◽  
Air Conditioning System ◽  
Environmental Friendly ◽  
Hfc 134A ◽  
Expansion Valve ◽  
Suction Line ◽  
Suction Line Heat Exchanger

In this work, the experimental investigation on the performance and exergy analysis of mobile air conditioning system with suction line heat exchanger using environmental friendly HFO-1234yf was carried out under varied evaporator air flow rates. The performance was compared with existing HFC-134a results. The performance analysis showed that the cooling capacity and the coefficient of performance of the system with HFO-1234yf were lower than that of the HFC-134a by upto 2–11%. The power consumption and the volumetric efficiency of the compressor with HFO-1234yf were found to be 14.02% and 11.2% higher than that of HFC-134a. From the exergy analysis, it was observed that the major exergy destruction occurred in the compressor, followed by the condenser, evaporator, thermostatic expansion valve, and suction line heat exchanger for both refrigerants. The exergy efficiency of the system with HFO-1234yf was 2.4–12.6% lower than that of HFC-134a. From this study, it was observed that the losses experienced in the compressor, thermostatic expansion valve and evaporator lead to poor performance with HFO-1234yf.

DESIGN OF THE CABIN CONDITIONING SYSTEM OF AGRICULTURAL MACHINE

2020 ◽  
Author(s):  
Y.I. Babenkov ◽  
◽  
A.I. Ozersky ◽  
V.V. Romanov ◽  
G.A Galka ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Good Health ◽  
Cooling Capacity ◽  
Air Conditioning System ◽  
Agricultural Machine ◽  
Hard Currency

The article is devoted to the issue of designing an air conditioning system (SСA) of the cabin of an agricultural machine to create comfortable conditions and ensure good health of the driver. The methodology for determining heat inflows and moisture inflows into the cabin is shown. The required cooling capacity of hard currency is calculated using the i-d diagram.

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