Characteristic Investigation on Flow and Heat Transfer of Capillary Pump in AMTEC

Abstract

AMTEC power is limited by the converter’s hot and cold end temperature, and also limited by the performance of capillary pump. The capillary pump with micro fluidic performance, it’s performance mainly affected by the geometric parameters of the porous media, hot and cold end temperature, electric current, etc. The capillary pump will become invalid during some special periods of AMTEC, such as start, stop, drying up in the case of operation condition change. Once the capillary pump is down, the working fluid would not get sufficient power for circulating, result in running with unsteady state. The special porous medium structure of the capillary pump such as multi stages of different segments with different pores with changing size, the heat conducting to capillary pump, the interfaces between condenser, capillary pump, evaporator. This will make the fluid flow in the porous media be complex, and it will couples micro-fluidic with heat and mass transfer, also include phase changing process. Numerical simulation is a good way to investigate some fluid relate topics, such as porous media, two-phase phenomenon, graded porous material, micro-fluidic. Using commercial code to simulate some flowing is a good way to solve some problems with challenging for test rig setting up. COMSOl is open source code to simulate some multi-physics field topics. This paper built a detailed mathematical model, used COMSOL soft to simulate the working process of the capillary pump of the AMTEC, and quantitatively calculated pressure loss and thermodynamic limit of capillary pump, analyzed the effect of basic parameters of the porous medium on the pressure loss and heat transfer characteristics, analyzed the reliability of the capillary pump at different temperatures. The simulation results are compared with other papers, drew some conclusions for the designing of capillary pump of AMTEC. The method and simulation results will be useful for AMTEC research.