Abstract
Activation time and discharge time are important criteria for the performance of thermal batteries. In this work a heat transfer analysis is carried out on the working process of thermal batteries. The effects of the thicknesses of heat pellets which are divided into three groups and that of the thickness of insulation layers on activation time and discharge time of thermal batteries are numerically studied using Fluent 15.0 when the sum of the thickness of heating plates and insulation layers remain unchanged. According to the numerical results, the optimal geometric parameters are obtained by using multi-objective genetic algorithm. The results show that the activation time is mainly determined by the thickness of the bottom heat pellet, while the discharge time is determined by the thickness of the heat pellets and that of the insulation layers. The discharge time of the optimized thermal battery is increased by 4.08%, and the activation time is increased by 1.23%.
Highlights
Thermal batteries, which are widely used in missiles and other modern weapons, have the advantages of long storage time, no self-discharge, quick activation and high reliability [1,2,3,4].Unlike conventional batteries, thermal batteries need to operate at very high temperatures in order to melt the electrolyte, which is a solid at room temperature, which causes them to activate and discharge outward
It can be found that reducing the thickness of the heat pellets can prolong the discharge time of the thermal battery, which inevitably leads to an increase in the activation time
The optimal geometric parameters of thermal battery are obtained by multi-objective optimization of thermal battery by genetic algorithm
Summary
Thermal batteries, which are widely used in missiles and other modern weapons, have the advantages of long storage time, no self-discharge, quick activation and high reliability [1,2,3,4]. Krieger et al [9,10] investigated the effects of gases and gas mixtures on global thermal conductivity values of porous thermal insulation packages of fully assembled low cost competent munition (LCCM) thermal batteries using transient and quasi-steady-state heat transfer techniques Their results indicated that filling the thermal battery with an inert gas, such as krypton or xenon, significantly prolonged the discharge time of the thermal battery. In the manufacture of thermal battery, the thickness of heat pellets should be increased to shorten the activation time, while the thickness of insulators should be increased to extend the discharge time. Both cannot be satisfied at the same time for a given shell.
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