Experimental Study of Hydrodynamics and Heat Transfer in a Loop Thermosyphon for Thermal Control of Power Plants of Electric Aircraft

The heat-transmitting capability, i.e., the ability to transfer heat flux with minimal losses, of thermosyphons and the prospects for using passive systems based on them for heat exchangers of various purposes, such as those for the utilization of heat from renewable energy sources and secondary energy resources (water basins, soil, groundwater, waste water and steam from industrial production, etc.) are considered. In small-scale power engineering, thermosyphons can be used to increase the potential of heat pumps that use heat from alternative sources. Passive heating/cooling systems ensure savings in the electricity required to power electric motors. Thermosyphons are easy to operate, do not require constant maintenance and can be effective intermediate links between heat sources and consumers, and are capable of maintaining a constant temperature of cooled objects. They can be used to organize the removal and transfer of heat outside a high-temperature environment. The design of a loop thermosyphon with a porous evaporator (LTSPE) and a condenser installed horizontally is presented. The article presents the results of experimental studies of a thermosyphon with two working fluids (freon R245fa and water). The temperature distribution and thermal resistances of the evaporator, condenser and thermosyphon as a whole are determined under different thermal loads. The effect of the cooling medium temperature on the heat-transmitting capability of the thermosyphon heated by a constant heat flux is analyzed. With an increase in the cooling medium temperature, the thermal resistance of the thermosyphon monotonically decreases. The studied device has a high heat-transmitting capability (up to 1.5 kW), a short start-up time, and a dynamic attainment of a steady-state mode when the load changes. The developed loop thermosyphons can be recommended for use in energy-saving systems, in particular in solar power engineering (thermal control of PV and PVT panels¹); in combination with heat pumps – in trigeneration plants generating electricity, heat and cold; in thermostatic equipment for electric transport, electronic equipment and in other areas