空气冷却热交换器翅片表面粗糙度约为20微米，大气中的蒸汽凝结成露珠，改善了翅片表面的润湿性，并将水滴变成一层薄薄的水膜。由于重力的作用，水很容易从翅片上脱落，与光滑表面的翅片相比，空气侧压力损失降低了30%。将光滑表面改为粗糙表面对百叶窗翅片的传热系数没有不利影响，百叶窗翅片有许多平行于气流的百叶窗。汽车用新型高性能蒸发器采用了粗糙表面翅片和百叶窗翅片的组合。引用:ASHRAE交易，第88卷，第2部分，加拿大多伦多

A fine surface roughness about 20micrometers on air-cooling heat exchanger fins, where steam vaporin the atmosphere condenses to dewdrops, improves wettability of fin surfaces and changes thedewdrops to a thin film of water. The water easily falls off the fin due to the force ofgravity, and the airside pressure loss decreases by 30% compared with that of smooth-surfacefins. Changing the smooth surface to the rough surface has no adverse effect on the heattransfer coefficient of louvered fins, which have many louvers parallel to the airflow. Newand high performance evaporators for automobiles have been developed using a combination ofrough-surface fins and louvered fins.