Abstracto

NUMERICAL ANALYSIS OF TWO PHASE FLOW IN FLAT HEAT PIPE

RakeshHari, C. Muraleedharan

Heat pipe is a thermodynamic device of very high thermal conductance. In a heat pipe the working fluid experiences phase change both in the evaporator and condenser sections. The flat heat pipe (FHP) is a transmutation of the conventional heat pipes that finds applications to deal with high density electronic cooling problem due to their high thermal conductivity and reliability where large heat flux is to be transported through limited space. The paper presents a numerical analysis of phase changephenomenon in a flat heat pipe. The heat pipe modeling involves the principal physical processes of wick-liquid dynamics and movement of resulting vapour away from the evaporator through the heat pipe vapour space to the condenser. The analysis involves the simultaneous solution of two dimensional continuity, momentum and energy equations in the liquid wick and the vapour core regions with respective boundary conditions.Vapour flow in the vapour passage is assumed to be laminar and the heat dissipation at the condenser side is by forced convection. The axial velocity distributions and velocity vector plots are obtained along the vapour core and liquid wick region at steady state conditions. Two phase mixture model is formulated to investigate the phase change phenomena in the porous wick structure. The flow equations for liquid-vapour interface are solved using appropriate numerical technique.Nusselt number and Sherwood Number are plotted against wall saturation for boiling and condensation.