Abstract
A new inexpensive counter-flow heat exchanger has been designed and optimized for a vapor-compression cooling system in this research. The main aim is to experimentally and numerically evaluate the effect of an internal heat exchanger (IHX) adaptation in an automotive air conditioning system. In this new design of IHX, the high-pressure liquid passes through the central channel and the low-pressure vapor flows in several parallel channels in the opposite direction. The experimental set-up has been made up of original components of the air conditioning system of a medium sedan car, specially designed and built to analyze vehicle A/C equipment under real operating conditions. The results show that this compact IHX may achieve up to 10% of the evaporator capacity while low pressure drop will be imposed on this refrigeration cycle. Also, they confirm considerable decrease of compressor power consumption (CPC), which is intensified at higher evaporator air flow. A significant improvement of the coefficient of performance (COP) is achieved with the IHX employment too. The influence of operating conditions has been also discussed in this paper. Finally, numerical analyses have been briefly presented, which bring more details of the flow behavior and heat transfer phenomena, and help to determine the optimal arrangement of channels.
Highlights
In cooling/refrigeration industry, liquid-suction or internal heat exchangers (IHXs) are installed in vaporcompression refrigeration systems to exchange energy between relatively cool low-pressure gas and warm highpressure liquid refrigerants
The pressure drops of the low-pressure vapor over passing through two IHXs of 10 and 30 cm are respectively equal to 2.9% and 6.1% of the inlet pressure, which are suitable in comparison with other IHXs
The capacity of IHX is equal to multiplication of refrigerant mass flow rate and difference of inlet and outlet enthalpies, which could be calculated from temperature and pressure of the inlet- and outlet refrigerant
Summary
In cooling/refrigeration industry, liquid-suction or internal heat exchangers (IHXs) are installed in vaporcompression refrigeration systems to exchange energy between relatively cool low-pressure gas and warm highpressure liquid refrigerants. The main advantages of the IHX installation are: increasing refrigerating effect at the evaporator, sub-cooling liquid refrigerant to ensure liquid phase entrance to the expansion valve, and minimizing the risk of liquid refrigerant entering at the compressor inlet. Using IHX has been studied mostly in CO2 refrigeration systems. [10] identified a dimensionless group to correlate performance impacts attributable to the IHXs, and studied the impact of pressure drops through the IHXs on system performance. They concluded that for given operating conditions the advantages are higher for R134a than R407C and R22
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