Visualization of thermo-fluid behavior of loop heat pipe with two evaporators and one condenser under various orientation with even heat loads

In this research, we visualized the operating behavior of a Multi-evaporator loop heat pipe (MLHP) with two evaporators and one condenser under even heat loads conditions when the evaporators were equally heat-loaded and investigated the detailed internal flow phenomena of the MLHP, such as flow patterns and vapor-liquid distributions in the condenser, evaporator cores and compensation chambers (CCs). Tests were conducted in three different attitudes to investigate the effects of gravitational head: a gravity -assisted attitude (i.e., the condenser was arranged at a higher position than the evaporators), a horizontal attitude (i.e., the condenser was arranged at the same height as the evaporators), and an anti-gravity attitude (i.e., the condenser was arranged at a lower position than the evaporators). In each test, the operating characteristics under each condition were also investigated by the temperature measured at each part of the MLHP. The relationship between temperature data and the corresponding visualization results, such as the vapor-liquid distributions, heat flow phenomena was confirmed. According to the test results, the MLHP in the gravity-assisted condition has the best operational performance with the lowest startup power, the highest heat transport capability, and the lowest operating temperature. The effects of gravitational head and the even heat loads conditions on the MLHP's vapor-liquid distributions, thermal resistance, condensation flow patterns, and heat leak ratios were also demonstrated.(c) 2022 Elsevier Ltd. All rights reserved.