Optimized Design of Solar/Air Collection and Storage Systems for HVAC
Abstract
A variety of hybrid or multi-source heat pump systems have been described in patents and academic literature, and are now beginning to be seen as commercial products. These systems often use solar thermal or related technologies. We describe here a comparison of several different methods to combine solar thermal collection with the collection of cold by means of convection and possibly night sky thermal radiation. Some of these cold collection methods are 1) the use of conventional unglazed solar thermal collectors; 2) a modification of the glazing surface designs of multi-pane windows. 3) the use of air to liquid heat exchangers (dry coolers). Another cold collection method (which is geographically restrictive) is the use of cold water deep in a lake, stream, river or ocean. This collection could be open loop or closed loop (heat exchanger in the water). We also describe herein several improvements in lower cost, long term storage of heat and cold underground. Extending the storage duration to six months will provide cost-effective seasonal storage. To gain the greatest advantage of what is described above, an optimized system of pumps, valves, and sensors will be used, along with computer control. Simulation results will be shown, along with examples of systems that have already demonstrated some aspects of the concepts herein. The end result of this type of system is the provision of both heating and cooling for buildings (either with or without the use of a water source heat pump), and in some cases the production of electricity, but without a need for direct use of fossil fuel.
Keywords
Hybrid system, Thermal energy storage, Solar heat, Geothermal heat pump, Dry cooler