Objective This paper evaluates the condensation heat transfer characteristics of small-channel condensers and provides reference for performance experiments and design applications 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 with an inner diameter of 1.27 mm. Using the control variable method, this study investigated 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 29%; the condensation heat transfer coefficient increases by 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 transfer performance; when the condenser liquid filling rate is 36%～61%, increasing the environmental temperature difference of the condenser, the condensation heat transfer coefficient increases by 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 ℃, reducing 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 30%～80% less than that when the windward area is unchanged; when the inclination angle of the condenser is changed from 0° to ±25°, the condensation heat transfer resistance of the condenser decreases, which is conducive to enhancing heat transfer.

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