Thermal performance of a tandem-dual-channel flat-plate pulsating heat pipe applicable to hypergravity

Abstract

Thermo-hydrodynamic characteristics of a novel flat-plate pulsating heat pipe (FP-PHP) with a symmetrically tandem dual-serpentine-channel were studied experimentally under the simulated hypergravity by a rotating platform capable of providing an adjustable centrifugal acceleration up to a = 4 g0 (g0 = 9.8 m/s2) on ground. The influences of gravity level, heat load, and orientation (i.e., circumferential orientation (C-O) and radial orientation (R-O)) on thermo-hydrodynamic performance of the FP-PHP were investigated. It is indicated that, similar to the traditional single-serpentine PHPs under the normal gravity, the quasi-steady flow motion in the FP-PHP under the hypergravity could be also classified into five flow patterns, i.e., stop-over, intermittent pulsation, pulsation, pulsation with circulation and circulation. Increasing hypergravity level is not conducive to the start-up process of the FP-PHP, which needs larger start-up heat load and higher start-up temperature. Even so, under a ≤ 4 g0, the FP-PHP can successfully start up within decent temperature level of 58 °C. Growing hypergravity level induces increasing negative influences on the thermo-hydrodynamic performance of the FP-PHP, which is more obvious under the R-O than that under the C-O. Anyway, in general, FP-PHP possesses a good thermal performance uniformity, which has an average coefficients of variation less than 3% in thermal resistance of its two symmetric halves. In addition, FP-PHP has an average equivalent thermal conductivity 4.38 times that of the pure 6063 aluminum alloy plate and a total weight 83.6% of it. The average equivalent thermal conductivity ratio of the FP-PHP under the hypergravity of a ≤ 4 g0 to that under the normal gravity is not smaller than 0.70, indicating a good adaptability of the FP-PHP to hypergravity. Accordingly, the FP-PHP could be regarded as a promising option for modern avionics passive thermal control systems for multiple heat sources.