SUMMARY

Oscillating heat pipes (OHPs), also known as pulsating heat pipes (PHPs) are passive heat transfer devices that may provide robust and low-cost solutions to many heat transfer problems. An OHP consists of a capillary channel partially charged with working fluid that transfers heat through fluid oscillations when a temperature gradient is applied. The adoption of OHPs in industry has been slow since they were developed in the early 1990s, largely due the difficulty in predicting OHP performance without experimental testing or computationally expensive CFD analysis. Simplified OHPs models has proved difficult to develop because OHP operation is not completely understood, and the phenomena that govern operation are complex.
In this work, a novel analytical OHP model is developed with insights gained from a review the literature regarding modeling and experimentation. The model was designed for OHPs experiencing slug flow and operating without flooding in their condensers. It was compared to previous experimental data and was found to predict the temperature drop within ±30% for 84.5% of the experimental data analyzed. The model consists of approximately 102 equations and unknowns which allows for rapid solutions with little computational power.
Aspects of the model were applied to produce a novel, helix shaped OHP design that is expected to perform with reduced thermal resistance by promoting flow circulation. The OHP and a testing system has been fabricated and testing is underway.
The advances in the understanding of OHP operation and the analytical model developed can be leveraged to explain confusing trends in experimental results, lower the uncertainty of OHP performance, and to develop novel designs with improved performance. The development of the novel helical OHP may lead to improved heat transfer performance in a variety of 3-dimensional systems.