Evaporative Condensation Air-Conditioning Unit with Microchannel Heat Exchanger: An Experimental Study

A new evaporative condensation refrigerant pump heat pipe air-conditioning unit based on a microchannel heat pipe heat exchanger is proposed. Performance experiments were conducted on the unit, and the experimental results show that the cooling capacity of the unit in the dry, wet, and mixed modes can reach 112.1, 105.8, and 115.4 kW, respectively, the optimal airflow ratio of the secondary/primary airflow is 2.2, 1.8, and 1.8, respectively, and the EER decreases with increasing airflow ratio. With increasing dry- and wet-bulb temperatures of the secondary-side inlet air, the cooling capacity and energy efficiency ratio of the unit decrease, and the energy efficiency ratio in the wet mode is higher than that in the dry mode, which can prolong the operating hours of the wet mode within the operating temperature range of the dry mode and improve the energy efficiency of the unit. A new calculation method for the refrigerant charge is proposed, and the optimal refrigerant charge is 32 kg based on the experimental results, which agrees with the theoretical calculation results.