Dynamic thermal response characteristics of a metal foam enhanced horizontal loop thermosyphon

A metal foam horizontal loop thermosyphon (MF-HLTS) for a solar receiver was proposed and investigated under the variable conditions. Meanwhile, a dynamic response model for predicting the thermal response characteristics of MF-HLTS was established using Nusselt theory and lumped parameter method. Results of the dynamic model show good agreement with the experimental data, with a maximum deviation of 3.5 % for temperature response. Under sudden power conditions, the temperature variation curve of MF-HLTS shows a progressive monotonic change with two stages: both rising and decreasing rates of temperature show linear and rapidly changes at first stage, and them begins to decrease and gradually tends to 0 at second stage. The time required to reach steady-state increases with the increase of power step. For start-stop of power and cooling, the recovery time gradually increases with increasing stop time, but start-stop ratio firstly decreases rapidly and then tends to be flat. Dynamic response of MF-HLTS is relatively fast with a temperature time lag of 2 s to 4 s, which can meet the requirements of dynamic regulation of system temperature under actual conditions.