Experimental Investigation of the Pressure Drop of the Liquid Refrigerant in the Copper Tube Used in Air Conditioning Condensers
Abstract
Air-conditioning systems used in vehicles are required to deliver higher performance than those used in residential or stationary building applications due to their dynamic operating environments, stringent thermal comfort requirements, and the limited space available for system installation. Pressure drop in the tubes used in condensers and evaporators of automotive Heating, Ventilation, and Air Conditioning (HVAC) systems significantly affects compressor sizing and overall system performance. In HVAC applications, minimizing pressure drop while maintaining a high heat transfer coefficient is essential for improving energy efficiency and reducing compressor power consumption. This study presents an experimental investigation of the pressure drop characteristics of liquid refrigerants R-134a and R-1234yf flowing through a smooth circular copper tube. The variations in pressure drop were analyzed as a function of refrigerant mass flux and Reynolds number. In addition, friction factors were determined from the experimental data and compared with the widely used Blasius correlation. The resulting coefficients were evaluated against those predicted by the Blasius equation. The results indicate that the frictional pressure drop increases with increasing refrigerant mass flux for both refrigerants. The findings contribute to a better understanding of refrigerant flow behavior in compact heat exchanger tubes and provide valuable data for the design and optimization of high-performance automotive HVAC systems.
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