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Solar Decathlon

Engineering Spotlight: Phase Change Material Thermal Storage System

matt's picture

Submitted by matt

Submitted on Mon, 08/22/2011 - 14:04

Installing the panels.

Team enCORE: Engineering Spotlight: PCM Plenum from Brandon Pence on Vimeo.

One of the most unique aspects of enCORE is its ability to store heat generated from the solar thermal hot air collectors for extended periods of time. The team accomplishes this goal using phase change material panels. The short answer as to what a PCM system does is that they are a thermal battery which stores 30 hours of hot air at 86 degrees F. The long answer continues below...

Phase change materials may sound exotic, but in fact we encounter them on a nearly daily basis. The next time you are enjoying a cold drink take some time to consider the functionality of the ice in it. As the ice melts (changes phase) it acts as to maintain the drink at approximately 32 degrees F. The functionality of the phase change material in enCORE is much the same except for one key difference, it changes states at 86 degrees F! This is the same temperature which we wish to deliver heating supply air to the house. Having such a material allows the control system to open a series of dampers which send a stream of air heated using our collection system to the plenum. This air melts the phase change material which is now storing energy for later use. Why is this so useful? Consider a fall day, it is a pleasant 65 degrees outside at 4 PM, however, the weather forecast calls for a 45 degree night. Clearly the house may demand no space heating or cooling during the day but will almost certainly need some heating overnight. The control system in enCORE will react to these parameters by examining national weather service data and pre-charge the phase change material for use overnight.


A rendering of the plenum