Investigation of Multiphase Heat transfer by Surface Modification Technique

Abstract Numerous passive techniques are proposed to modify the surfaces to enhance heat transfer for energy efficient systems. Nucleate boiling is one of the important regimes in pool boiling. Most of the heat removal systems are operated under burnout point. Beyond this stage the heat removal system will be operated on radiation mode of heat transfer. This mode of heat transfer makes the system to be complicated and it is not safe to operate heat transfer components under this condition. So any removal system has to be operated above critical heat flux. Wettability is one of the primary factors which influence the pool boiling characteristics. In the present work the wettability of different grades of emery abraded copper surfaces were studied and critical heat flux on the Emery Abraded copper surfaces were investigated. Copper surfaces are abraded with different grades of emery sheets. The wettability of the surface was analyzed by determining water contact angle on the surface. The water contact angle of the surface was measured by goniometer. Also in this work characteristics of the emery abraded surface were studied. Critical heat flux of the bare copper and emery abraded copper surfaces were compared. In this investigation the critical heat flux of the emery abraded surface is enhanced considerably and it higher than that of bare copper surface.Also boiling heat transfer coefficient for bare copper surface and emery abraded surfaces were compared. Improvement in boiling heat transfer coefficient on abraded surfaces results better heat transfer were happened in nucleate boiling conditions