The Research On The AMTEC Heat Lost

The alkali metal thermoelectric converter that is based on β "alumina solid electrolyte asa core component, using sodium as the working fluid, which allows sodium ions in its crystalstructure along the atomic plane motion without letting electronically through it, isthermoelectric energy directly conversion of new generation devices. It is a new type ofenergy converting device of high power density, high efficiency. non-pollution, non-noise andhigh reliability, which could be suitable for various kinds of heat resources. Theoreticallythermoelectric energy conversion efficiency is up to30%to40%, due to the presence of theheat loss in the actual operation, the efficiency is only15%to20%. AMTEC internal radiationheat loss accounts for the major part.In this paper, DO thermal radiation model was used for simulating radiation aboutimpacting radiation heat transfer factors. The main work of this paper are:(1) considering theimpact of the cold end temperature for the heat transfer and the heat loss of AMTEC,(2)calculating radiation heat loss of BASE tube under different surface emissivity,(3) comparingtemperature distribution and heat loss between adiabatic wall and heat exchanger wall ofAMTEC,(4) analyzing effect of the heat shield on radiation heat transfer,(5) discussing therole of the geometric parameters of the BASE tube and AMTEC on heat loss,(6) comparingwith three different structural forms heat shield to provide the best solution for the futuredesign. AMTEC temperature distribution, the axis of the internal radiation intensity andtemperature change graph along BASE tube are obtained by FLUENT code. The heat in themain components and the radiant heat loss are calculated to optimize the structure ofAMTEC.The results show that BASE tubes temperature changes in proportion to the temperatureof the cold end. The temperature of the low-pressure cavity is mainly influenced by thetemperature of the cold end. Surface emissivity has little effect on the wall temperature andthe increase of the emission rate directly affects the radiation heat exchange, resulting BASEtube radiant heat loss increases. With the increase of the convective heat transfer coefficient,heat dissipation of wall and BASE tube radiant heat loss is same in some sence. Arranged theheat shield above the BASE tubes, the radiant heat is reduced, which is transferred fromBASE tubes to wall. As a result, the temperature of the BASE tubes is increased.It is found out that radiation intensity is significantly different at the front and back of the heat shield.When a conduction stud is added, most of heat flows to the capillary evaporator so thatraising the temperature of the wick through the conduction stud. The length of BASE tubes islittle effect on AMTEC internal temperature distribution. The shortening the height of the highpressure cavity will increase the internal temperature of the base tube and the AMTEC, whileincreasing heat absorption in each section, as a result the BASE tubes radiation loss israised.The cylindrical heat shield can obstruct most of radiation heat so the radiat heat loss ofthe BASE tubes is reduced significantly.