Evaluation of Commercially Available Microencapsulated Phase Change Material Slurries in Hydronic Heating and Cooling Systems.

摘要

This study describes the results from thermal cycling and pumping tests designed to test the suitability of using commercially available paraffin based micro-encapsulated phase change materials in hydronic systems used to distribute heating and cooling in commercial or large residential buildings. The thermal cycling tests were conducted. The thermal cycling tests determined that the micro-encapsulated phase change materials did not experience a major change in the melting temperature or degree of super-cooling. The latent heat was however reduced after several thermal cycles. The latent heat stabilized after 100 thermal cycles . A pumping test was conducted using a centrifugal pump and a pipe circuit, and analysis indicated that many of the mPCMs ruptured and gathered around the impeller of the pump. A Laser-In situ Scanning and Transmissiometry instrument was used to determine the particle size distributions (PSDs) of virgin mPCM samples, as well as samples that had been thermally cycled, and that had been pumped in the pipe circuit. These tests indicated no change in particle size distribution after thermal cycling, but that most of the micro-encapsulated phase change materials that ruptured due to pumping were greater than 10mum in diameter. Based upon these efforts, it was concluded that for this technology to work in building applications, either smaller-diameter micro-spheres or some other type of pumps would need to be used. It was also concluded that a more detailed profile of the decay of latent heat would need to be conducted.