Heat transfer performance variations of condensers due to non-uniform air velocity distributions

•Non-uniform air velocity was measured on outdoor unit.•Non-uniform air flow effect was investigated using numerical method.•Heat transfer performance was always reduced by a non-uniform air flow.•Capacity reduction rate increased as the average air velocity decreased.

The heat transfer performance variations of condensers that are caused by non-uniform distributions of air flows are investigated using a numerical simulation method. A heat exchanger designed for the outdoor unit of a heat pump system is selected and represented using a numerical model. A non-uniform profile of the air velocity is constructed through measuring the air velocity at various locations on the outdoor unit. Numerical analyses are conducted for various refrigerant circuits and air flow conditions. The results demonstrate that the heat transfer capacity is reduced depending on the air flow rate and the refrigerant circuit configuration. It is also demonstrated that the capacity reduction rate is increased as the average air velocity decreases.