Pulsating Heat Pipes: Thermo-fluidic Characteristics and Comparative Study with Single Phase Thermosyphon

$EVWUDFW This paper presents an experimental study of Pulsating Heat Pipes (PHP), having potential applications in microelectronics thermal management [1]. The PHP is made of 10 parallel glass tubes (ID: 2 mm, OD: 4.2 mm, 100mm long) forming the adiabatic section, interconnected alternately by copper U-tubes forming part of the water-cooled condenser and the electrically heated evaporator section. Working fluids employed are water and ethanol. Thermal response and operational characteristics of the device are studied under different operating regimes. Internal flow pattern visualization is done and various bubble/slug sizes and patterns are characterized, having an important effect on the performance. Although a PHP is recognized as a two phase heat transfer device, for comparative studies it is operated as a single phase system by filling it 100% with the working fluid. This comparison has resulted in a better understanding of the underlying principles of the PHP operation. The fundamental thermo-fluidic processes occurring in the device operation are explained in detail. It is concluded that significant information is yet to be extracted until a complete theory of PHP operation may be proposed. This paper attempts to bridge the gap. ,QWURGXFWLRQWRSX OVDWLQJKHDWSLSHV