This book discusses the evaporation mechanism in the wick of copper heat pipes. The investigations are based on recent visualization experiments for operating horizontal flat-plate heat pipes.Introduction.- Experimental methods.- Water in mesh and powder wicks.- Different working fluids in 100+200 mesh wick.- Effects of surface wettability.- Conclusions.This book discusses the evaporation mechanism in the wick of copper heat pipes. The investigations are based on recent visualization experiments for operating horizontal flat-plate heat pipes.Discusses the evaporation mechanism in the wick of copper heat pipes Includes supplementary material: sn.pub/extras