Overview

 

The purpose of heating or air conditioning is to deliver or remove heat. Traditionally air, cold water, or refrigerant is piped into an area to be conditioned.

 

Energy is used to pump the fluid, and in the case of forced air systems some supply air is lost to leakage. Using water or refrigerant is preferable to forced air because water or refrigerants have a better ability to carry heat. To reduce the energy required to pump, the fluid should carry as much heat as possible.

 

Water has a large specific heat–it requires lots of energy to change the temperature a little. Just like using ice to keep a drink cold, phase change materials (PCM) are a suspended and encapsulated liquid or solid that can be inserted into water or building materials to increase its heat capacity. This increased heat capacity from the PCM has the potential to keep something cool for a longer period of time. When faced with increased heat, the PCM fluid will remain the same temperature for longer than traditional water or refrigerants because the increased heat goes into breaking the bonds of the phase change material instead of increasing the PCM-fluid’s actual temperature.

 

We hope to make a pump-able mixture of encapsulated phase change materials and water as our first experiment with PCM. Since the heat required to make a material phase change is enormous compared to the specific heat, the volume of our coolant can theoretically be decreased to get the same amount of thermal transport. Another potential energy savings using PCM in water is that it should allow for a reduction in pumping velocity of the water to maintain a similar amount of thermal transport and thus making fan coil units cheaper to run.

 

Objectives we hope to meet with our research:

  • The mixture must be pump-able
  • The PCM must not get clogged in the fan coils or the plumbing
  • It must be economically viable
  • The operating temperature range must include the phase changing temperature
  • The phase change material must not succumb to fatigue from thermal cycling