Experimental Study On Flat Loop Heat Pipe Based On Different Capillary Wicks Development Process

Loop heat pipe(LHP)is an efficient two-phase loop type heat pipe,which relies on the capillary force on the surface of the porous capillary wicks in the evaporator to drive the working fluid circulation in the loop to realize the heat dissipation of electronic devices and the evaporation / condensation phase transition of the working fluid to transfer heat,so as to realize the heat dissipation of electronic devices with high heat flux.In this thesis,the manufacturing process of loop heat pipe and the preparation methods of different capillary wicks are introduced in detail.The sintering method of d doubleaperture metal capillary wicks is optimized.The way to obtain directly sintered metal powder capillary wicks is explored.The metal mesh capillary wicks and sintered metal mesh capillary wicks are prepared.The direct pouring capillary wicks process and the supporting evaporator structure are developed.Based on the above mentioned capillary wick,a number of loop heat pipe systems were built,and the heat transfer performance of the system was tested.With stainless steel wire mesh as the capillary wicks,a multi-heat source aluminum alloy-acetone flat loop heat pipe was designed.The evaporator area was 190mm×90mm,the inner diameter of the steam pipe and the liquid pipe was 4mm,the filling rate was 75%,and the vapor line length was 414mm.A copper-methanol multi-heat sources loop heat pipe was built based on the pouring capillary wicks.The size of the evaporator was 180mm×90mm,the inner diameter of the steam pipe and the liquid pipe was 4mm,the filling rate was 70%,and the vapor transmission distance was 185mm.The total length of the condenser tube was 1220mm,covered with thin copper fins with a thickness of 0.2mm.The system has been tested for heat transfer performance under several different attitudes.The capillary wicks of nickel powder were prepared by secondary sintering,and the process method of secondary sintering of capillary wicks was introduced in detail.The size of evaporator was 35mm(D)× 14mm(H),the inner diameter of steam pipeline and liquid pipeline was 4mm,the filling rate was 75%,and the transmission distance was 462mm for the copper-methanol loop heat pipe built based on the capillary wicks.Complete transient response test of the system was tested,including constant heat load transient response,variable heat load operation,and variable condensation temperature test.In this thesis,the results lay a foundation for the preparation of capillary wicks with excellent performance,excellent sealing and low cost in the future,and provides an experimental basis for the development and optimization of multi heat source loop heat pipe in the future.