The Experimental Investigation on Transpiration Cooling : 3rd Report, The Case Using Dry Saturated Vapor or Superheated Vapor as a Coolant

Abstract

The heat transfer phenomenon of transpiration cooling using the distilled water as a coolant was experimentally investigated; especially, for the case that the coolant changes into superheated vapor in the porous test plate, the experimental studies were performed. As the rusult of the above investigations, the following conclusions were obtained: (1) The cooling efficiency in the case that the coolant changes into superheated vapor in the porous plate can be accurately estimated from the condition that the coolant changes into dry saturated vapor on the porous plate; (2) The heat transfer coefficient goes down with a decreasing coolant flow rate at first, but then it increases again gradually; and (3) With an increase of pore size of the test plate, the cooling efficiency increases and the heat transfer coefficient decreases.