The development of heat exchangers in order to recover energy from industrial waste heat has
become an interesting topic for energy conservation programs. A thermosyphon heat pipe,
one type of heat exchanger, has been used in many industrial processes because of its many
advantages, such as its high thermal conductivity, low cost, and ease of construction
The thermosyphon heat pipe shown in Figure1 can be divided into three parts: the evaporator,
adiabatic, and condenser. When heat is added to the evaporator section, the working fluid
(water) inside the heat pipe is boiled and vaporized. The vapor carries heat from the heat
source, flows to the condenser section, and rejects heat to the heat sink. The working fluid
condensate returns to the evaporator section via gravity.
Normally, the performance of a thermosyphon heat pipe depends on the temperatures of the
heat source and heat sink. In the case of a low temperature heat source, the working fluid
inside the thermosyphon is normally difficult to boil, and the heat transfer between the
evaporator surface and the working fluid proceeds only via the free convection mode. In this
case, a poor heat transfer rate is obtained. In this paper, we use an ultrasonic wave to
overcome this problem by activating the heat transfer rate of the evaporator section.