Performance Improvement of Spiral Gas Cooler for the Heat Pump Water Heater

Abstract

We developed a new type of quadruple thread spiral tube in order to improve the heat transfer coefficient on the liquid side of the gas cooler. The COP of the heat pump water heater can be well improved by optimizing the performance of the CO2- water heat exchanger. In this paper, the improvement of heat transfer performance has been analyzed based on numerical and experimental verifications. As a result, the quadruple thread spiral tube can provide higher heat transfer performance by 12% compared with the current triple thread spiral tube. A correlation equation of the heat transfer coefficient is made on the basis of the measurement data. It has a prediction accuracy at ±20% compared with the experimental data.