Fabrication And Heat Transfer Performance Of Stainless Steel Heat Pipe By Powder Sintering

Recently,the research of passive cooling system for nuclear power field is critical due to the nuclear safety accident.Heat pipe is capable of transfering a large amount of heat depending on the phase transition of working medium without extra power supply,which has received much attention and practical application in the field of temperature control.In view of the stainless steel could be applied to the harsh environment of nuclear power station,such as high temperature,high pressure,strong radiation and strong corrosive.However,the current stainless steel heat pipe is mainly about the gravity heat pipe and heat pipe with grooves or mesh wick structure,and few studies and reports of the stainless steel heat pipe by powder sintering.In order to put forward a feasible scheme for passive cooling research of nuclear power field,a kind of stainless steel heat pipe by powder sintering is proposed.The main work of this paper is as follows:(1)Study on sintering process of stainless steel powderThe influence of sintering temperature,sintering time and sintering atmosphere on sintering wick were discussed in this text,and the suitable solid phase sintering process for stainless steel powder was determined.The morphology and composition analysis of sintered powder sample was proceeded utilizing the scanning electron microscope.The forming mechanism of solid phase sintering of stainless steel powder was analysed by observing the sintering neck of sintered samples with the aid of scanning electron microscope.(2)Performance characterization of sintering wick by stainless steel powderThe performance of sintering wick by stainless steel powder was studied,focusing on its wettability,permeability and capillary pressure.The integrated capillary performance of sintering wick was evaluated by the capillary performance factor S.And the effect of different morphology(spheroidal/irregular powder),different size and different medium on capillary performance was compared and analysed.The results obtained that the sintering wick by 90~120 um irregular stainless steel powder showed the optimal capillary performance with deionized water.(3)The manufacturing process and heat transfer performance of stainless steel heat pipeThe manufacturing process of stainless steel heat pipe by powder sintering was discussed.The strengthening heat transfer performance and heat transfer mechanism of stainless steel heat pipe by powder sintering was analysed with the comparison of gravity stainless steel heat pipe.The heat transfer performance of sintering heat pipe is better than that of gravity heat pipe no matter in vertical or horizontal state,the former has the more stable startup,the higher extreme heat transfer power and the more stable wall temperature.(4)The optimization of experimental parameters for stainless steel heat pipeThe study of parameters for the heat transfer performance of stainless steel heat pipe by powfer sintering was conducted,focusing on the effect of the heating power,medium liquid ratio,evaporation section length,cooling water flow rate and anti-gravity angle on the startup characteristics,extreme heat transfer power,thermal resistance characteristics and wall temperature distribution characteristics of sintering heat pipe.It turned out that the sintering heat pipe obtained the better heat transfer performance in the 100% medium liquid rate,high cooling water flow rate and long evaporation section,and the long sintering heat pipe is not conducive to develop the antigravity performance.