Investigation on the dynamic thermal response of jet evaporators to short-term thermal excitation

Abstract

This study investigates the dynamic thermal response of a jet evaporator under short-term thermal excitation in a mechanically pumped two-phase loop (MPTL) with a special focus on the temperature response characteristics of the jet evaporator under different flow and heat flux conditions. Two dimensionless numbers, Ja and Re, were proposed to characterize the thermal response. In addition, the time constant and transient time were introduced to evaluate the temperature response rate, whereas thermal stability was characterized by the temperature overshot amplitude. The results indicate that the gradual response mode, single-jump overshoot response mode, and twice-jump overshoot response mode can be sequentially obtained with an increase in the applied heat load, that is, an increase in Ja. The Re number influences the threshold value of the Jacob number for the response-mode transition. Elevating the heat load accelerates the thermal response rate of the jet evaporator and reduces its time constants, whereas increasing the flow rate enhances the thermal capacity and anti-interference ability. Furthermore, as the flow rate increased, the thermal capacity and anti-interference ability of the MPTL were enhanced, leading to an increase in the time constant and transient time. Notably, the twice-jump overshoot response exhibited a smaller temperature overshoot than the single-jump overshoot response, suggesting improved thermal stability.