Optimal design of variable-path heat exchanger for energy efficiency improvement of air-source heat pump system

The optimal number of paths for the heat exchanger of an outdoor unit of a heat pump system depends on whether this heat exchanger functions as a condenser or an evaporator. A variable-path heat exchanger (VPHE) is proposed that can provide an optimal flow path for both condenser and evaporator conditions with one heat exchanger. The performance of VPHE was numerically analyzed, and the results showed that both the heat transfer capacity and pressure drop of the VPHEs increased. The performance of a VPHE with an upper and lower region ratio of 34:24 was enhanced by 22.1% in terms of heat transfer capacity per pumping power. Based on numerical simulation results, the potentially optimal refrigerant flow path was selected and VPHEs were manufactured to be incorporated into a heat pump system. The performance of the heat pump was experimentally measured under heating conditions, standard cooling conditions, part load cooling conditions, and overload cooling conditions. It was demonstrated that the COP of the heat pump employing VPHEs was increased by 15% under the standard rating condition and by 23% under part load cooling condition.

Automated summary

A variable-path heat exchanger (VPHE) was proposed for optimizing the heat exchanger of an outdoor unit in a heat pump system. Numerical analysis and experimental measurements showed that the VPHE significantly improved heat transfer capacity and coefficient of performance, demonstrating potential for enhancing overall system performance.