Date of Award


Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Kizito, John Dr.


Thermal management is an important issue for applications that generate high heat flux. Choosing an efficient cooling technique depends on thermal performance, reliability, manufacturing cost, and prospects for minimization. Based on these grounds, loop heat pipe (LHP) is a highly efficient two-phase passive cooling system used for cooling of electronics and many critical components of spacecraft and satellite. Loop Heat Pipe (LHP) uses capillary action to circulate cooling fluid inside the loop. Pressure developed in the pores of a wick provides the driving force to circulate the fluid. LHP has superior heat transport capability and can operate at any orientation. In the present study, a loop heat pipe with flat evaporator has been designed and manufactured and an experimental study was performed to investigate the effects of various parameters on loop performance. LHP was instrumented with thermocouples to measure the loop temperature at various positions. Temperature oscillations have been observed at the startup of LHP. Performance of LHP has been evaluated at a wide range of evaporator heat loads. In order to comprehend the complex phenomenon inside LHP, the main structure of LHP has been made from transparent acrylic plastic to visualize the evaporation and the condensation process. A high-speed video camera has been utilized to visualize the operational process. Data collected from the experiment provides a significant insight into the physics of LHP operation. An analysis is presented to explain the startup process. Understanding of startup process is necessary for predicting the performance of LHP.