2006 NIP Award Recipient
Investigation of Microencapsulated Phase Change Material Slurry as a Heat Transfer Fluid
Dr. Wilson Terrell - Trinity University
The goal of the proposed project for the Texas Space Grant New Investigations Award is to construct a test loop to measure the heat transfer coefficient and pressure drop of microencapsulated phase change material (MPCM) slurry in enhanced tubes for use in thermal control of space systems. MPCM consists of the phase change material, encapsulated in a nucleating agent. As this cold slurry travels through a heat exchanger, the encapsulated material goes through a phase change from solid to liquid, thus it can absorb more energy than other, single-phase fluids, which could lead to the benefit of reduced pumping power. While there have been studies of MPCMs as a heat transfer fluid, very few have focused on enhanced tubing. Enhanced tubing has extended surfaces on the inside, which promotes mixing of the heat transfer liquid. The mixing can enhance the exchange in energy between the heat transfer fluid and the surrounding air, thus allowing use of smaller heat exchangers. Smaller heat exchangers would lighten the load on a spacecraft. Dr. Terrell's research project is very relevant to NASA’s goal of extending the duration and boundaries of human space flight. A better understanding of new heat transfer fluids that potentially could be used in indirect refrigeration systems would benefit many life-support/human performance areas such as temperature/humidity control, cooling of electrical devices, and food storage. The experimental results obtained from this project will be pertinent not only to the thermal control of space systems, but also to other areas such as supermarket refrigeration, thermal control of electronic equipment and air-conditioning. Dr. Terrell's primary research focus is the experimental assessment of novel refrigeration and airconditioning systems and components. One of his research interests is to investigate buoyancy driven convection in open cavities, which simulate refrigerators. The goal is to understand how much water and energy are transported into a refrigerator by this mechanism. The past summer, construction started on new cavities of different sizes in order to measure local heat transfer coefficients. He currently has an undergraduate student volunteering help with the completion of the cavities. Another research interest is smoke visualization of buoyancy driven convection flow around heated 3-D objects. An undergraduate research assistant has conducted an initial literature search, has investigated various types of smoke generation, and has started initial design of a test platform.