Role of hypergravity in minichannel flow boiling

Abstract

The minichannel boiling in a pumped two-phase fluid loop is an efficient thermal management for modern fighter jets in hypergravity environment. A variable-speed rotating platform is constructed to simulate the hypergravity environment. An experiment of the mechanically pumped two-phase fluid loop is conducted to investigate the flow boiling characteristics of minichannel evaporator under hypergravity conditions, with a focus on the centripetal and centrifugal radial flow modes. In addition, the dynamic heat transfer performance of the evaporator under centrifugal and centripetal flow modes is quantitatively evaluated by the average wall temperature, heat transfer coefficient, critical hypergravity acceleration. The results indicate that, the role of hypergravity in minichannel flow boiling in centripetal flow mode differs from that in the centrifugal flow mode. In the centripetal flow mode, the wall temperature of minichannel evaporator exhibits the "L"-shaped trend with respective to the hyper-gravitational acceleration, suggesting that hyper-gravitational acceleration contributes to heat transfer enhancement. In the centrifugal flow mode, an increase in hyper-gravitational acceleration leads to an overall "V"-shaped trend in the wall temperature of evaporator, indicating that there is optimum boiling performance at an appropriate hyper-gravitational acceleration. In addition, the critical hypergravity acceleration increases as the rise of flow rate in the centrifugal flow mode, no critical hypergravity acceleration is observed in the centripetal flow mode.