Based on a three-dimensional distributed parameter model

a simulation model of a small-diameter heat exchanger in the indoor unit of a split-household air-conditioner was established

and the performance metrics were computed

including the total heat load

sensible heat load

latent heat load

refrigerant-side pressure drop

and air-side pressure drop. The effects of the tube length

refrigerant mass flow rate

air volumetric flow rate

air inlet temperature

and air inlet relative humidity on the heat exchanger performance metrics were determined under different working conditions. For the 5 mm diameter heat exchanger considered in this study

the corresponding tube length range was 0.6~0.7 m

achieving good heat transfer with a small pressure drop. Owing to the comprehensive influence of the heat transfer coefficient and the effective mass transfer time

when the volumetric flow of air was in the range of 600–700 m3/h

the latent heat load reached a maximum of 426 W. With an increase in the air inlet temperature

the sensible heat load first increased and then decreased.