Heat pipes and heat exchangersHeatexchangers" \r "TEBK8945 are integral components in various engineering applications, spanning HVAC systemsHVAC systems, industrial processes, refrigeration, and geothermal energy systemsGeothermalenergysystems" \r "TEBK8953. In the context of this book, a heat pipe acts as a conduit for heat transfer, utilizing a working fluidWorking fluid" \r "TEBK8958 to transport heat along its length and facilitate thermal interaction with the surrounding environment. The flow of the working fluid within heat pipesHeat pipes" \r "TEBK8965 is unidirectional, entering from one end and exiting from the other. Similarly, a heat exchanger serves to transfer thermal energyThermalenergy between fluids and their surroundings. However, unlike heat pipes, the flow of the working fluid is multidirectional. The heat exchangers either employ several unidirectional channels carrying fluids moving in opposite directions or utilize the same fluid flowing through inner and outer pipes forming U-tubesU-tubes.