Objective This paper evaluates the condensation heat transfer characteristics of small channel condensers and provides reference for performance experiments and design application of condensers.

Method The experimental device for testing the performance of condenser was set up in the enthalpy difference laboratory. The condenser was composed of flat tubes of 1.27 mm inner diameter. By using control variable method, the experimental device could be used to study the effects of environmental temperature difference (3～21 ℃), liquid filling rate (16%～61%), windward area (0.019～0.041 m²) and inclination angle (0° and ±25°) on the condensation heat transfer coefficient.

Result The results show that: the condensation heat transfer coefficient increases slightly when the condenser liquid filling rate increases from 16% to 21%; the condensation heat transfer coefficient increases about 3.5～4.2 times when the condenser liquid filling rate increases from 29% to 61%; when the condenser liquid filling rate is not more than 29%, the environmental temperature difference has slight effect on the condensation heat exchange performance; when the condenser liquid filling rate is 36%～61%, increase the environmental temperature difference of the condenser, the condensation heat transfer coefficient increases about 1.4～1.9 times at first, and then decreases to about 60% of the maximum condensation heat transfer coefficient; the effect of the windward area on condensation heat exchange performance of the condenser is related to the environmental temperature difference; when the environmental temperature difference is 9～21 ℃, reduce the windward area of the condenser, the condensation heat transfer coefficient decreases first and then increases; when the windward area of the condenser is reduced to 0.026 m², the condensation heat transfer coefficient decreases to the minimum value, which is about 30%～80% less than the condensation heat transfer coefficient when the upwind area is not changed; when the inclination angle of the condenser is changed from 0° to ±25°, the condenser condensation heat transfer thermal resistance decreases, which is conducive to strengthening heat exchange.

Conclusion This study is helpful for the application of enhanced heat transfer in small channel condensers and provides experimental basis for the performance optimization of condensers.