Development of a Gravity-Assist Water Loop Heat Pipe With Flat Evaporator for Waste Heat Removal

Use of capillary pumped heat transport devices such as heat pipes, Capillary Pumped Loops (CPLs), and Loop Heat Pipes (LHPs) are being considered for cooling of shipboard electronics. These capillary devices contain no mechanical moving parts to wear out, require no electrical power to operate, and demand virtually no maintenance. Heat pipes have been the mainstay of spacecraft thermal control systems over the past 30 years. However with limited pumping heads, heat pipes were utilized only in a few terrestrial applications. Successful demonstration of much higher pumping capability of CPLs and LHPs in recent years now makes them feasible for ground-based heat transport systems. Fluid management in a gravity environment is also much easier that the traditional design of a CPL/LHP does not really apply to terrestrial systems. In addition, a gravitational pressure head generated by a vertical distance between the condenser and evaporator can assist the capillary pumping to augment the overall pumping capability of the loop. Thus, when properly designed, a gravity-assist CPL/LHP can transport a large amount of waste heat over a long distance for dissipation.