Optimal refrigerant flow configurations in a fin-tube heat exchanger for an indoor unit of a heat pump using R466A

This study investigates the optimal refrigerant flow path for a fin-tube heat exchanger used in the indoor unit of a mini VRF heat pump. Optimal circuitry can significantly enhance the performance of fin-tube heat exchangers. Its performance according to various refrigerant circuitry is evaluated by the developed finite-element-calculation simulation model. The refrigerant circuitry was optimized by maximizing the heat transfer rate for given refrigerant and air conditions during cooling and heating seasons by adopting an optimization algorithm. A four-circuit circuitry has a higher capacity than the six-circuit circuitry and two-circuit circuitry because of the balancing effect of pressure drop and heat transfer. The best circuitry, which contains split/merge tubes, has a higher capacity and a significant pressure drop reduction compared to the two-circuit circuitry. It is found that compared to the reference circuitry, the best circuitry for the indoor unit of the heat pump has a 13 % increase in capacity.