Experimental and Analytical Study of Dual Compensation Chamber Loop Heat Pipe under acceleration force assisted condition

Abstract

In this article, a combined experimental and theoretical study has been conducted to investigate the operating characteristics of a dual compensation chamber loop heat pipe (DCCLHP) with ammonia as the working fluid under acceleration force conditions. The DCCLHP with nickel wick consists of a cylindrical evaporator and dual compensation chambers at both ends of evaporator. In the current study, a new DCCLHP test rig is set up which can provide the acceleration up to 11 g. Two types of loading mode are utilized for applying heat load prior to acceleration. The heat load ranges from 25 W to 300 W. Comparisons of operating performance of the DCCLHP are carried out under both gravity and acceleration conditions. A novel acceleration force assisted concept is proposed to address the observed operating behavior. Experimental results show that: (i) the acceleration effect with the proposed orientation can improve the operating performance of the DCCLHP which may operate at the centrifugal force driven mode and capillary-centrifugal force co-driven mode. The operating temperature profile at different heat loads shows “/-shape” oblique line with the increase of the acceleration; (ii) the transition heat load from centrifugal force driven mode to capillary-centrifugal force co-driven mode changes with the variation of acceleration magnitude at both loading modes; (iii) the acceleration effect on the operating temperature is remarkably significant as the heat load is less than 100 W. The operating temperature under acceleration conditions is apparently lower than that under terrestrial gravity; (iv) the coupling change of the loop pressure, vapor-liquid distribution, two-phase flow and heat transfer caused by acceleration effect leads to the unique operating performance of the DCCLHP.