Concept and performance of a solar assisted heat pump using ice slurry as a phase change storage medium.

In Canada, there is often enough solar energy to meet building heating demand in the winter months. However, solar availability and heating loads generally do not coincide, requiring innovative ways to store and later retrieve captured solar energy. A new concept utilizing a glycol-water-ice tank (fluid temperature < 0°C) to store the energy collected from solar thermal collectors, and an ice slurry heat pump to extract the energy from the tank for building heating was developed and tested. Advantages of this concept include higher energy storage densities, and improved collector efficiencies. The recovered solar energy was measured during a heating season in Montreal, Canada, showing that about 60% of the available solar energy is recovered in the coldest winter months. The instantaneous coefficient of performance (COP) of 2.98 was measured for a space heating strategy. This concept has the potential to significantly decrease greenhouse gas emissions from the building sector.