Thermal Performance Evaluation of Flash Evaporation in Wickless Heat Pipes With Jet Nozzle for Desalination

ABSTRACT This study presents a numerical and experimental investigation of the effect of flash evaporation on the thermal performance of a wickless heat pipe used in desalination applications. Moreover, this study examines the factors that affect flashing efficiency, such as the feed water mass flow rate, inlet temperature, and cooling water flow rate. The thermal performance of a wickless heat pipe with flash evaporation caused by a micro‐scale jet nozzle with a 0.4 mm diameter is evaluated using 3D numerical simulations with ANSYS Fluent 22.2. The two configurations of the heat pipe are studied based on the nozzle position. In the first configuration, the nozzle is located far from the condenser. In the second configuration, the nozzle is positioned close to the condenser. These two cases are examined under three water mass flow rates (0.00138, 0.0022, and 0.0025 kg/s) to evaluate the influence of nozzle position on flash evaporation intensity and overall thermal performance. Results showed that the first configuration exhibits superior thermal performance, a higher condensation mass flow rate, and greater flash efficiency compared with the second configuration. The optimum performance is achieved at an inlet mass flow rate of 0.0022 kg/s, where the flash efficiency reaches up to 78%, confirming that increasing the distance between the nozzle and the condenser enhances the flashing and condensation processes.