1. Field of the Invention
This invention relates to systems for space heating and cooling and, more particularly, to such systems particularly adapted to provide improved efficiency for residential use.
2. Description of the Prior Art
Heat pumps have long been used for efficiently transferring heat from one medium to another, thus permitting the heating or cooling of a given space with the heat being transferred from some readily available medium (ambient air, water in an adjacent lake or well, a body of rocks or salt, or the like) for heating, and being delivered to the medium (often the same body of water, etc.) for cooling.
For example, the Carleton patent, U.S. Pat. No. 3,135,318 describes a heat pump system using a turbo-compressor which provides power and waste heat to a standard vapor cycle refrigeration system. Two turbines are employed in the system, one driving the turbo-compressor and a second turbine driving a recirculating air fan and the refrigerant compressor.
The Miller patent, U.S. Pat. No. 3,822,561, describes a self-contained, portable air cooling unit comprising a refrigeration circuit, a thermal reservoir consisting of an ice bank in a flexible tank, and a heat exchanger for transferring heat between the air in the space to be cooled and chilled water circulated from the ice bank and reservoir. Means are provided to selectively and alternatively operate the refrigeration circuit and the circulating system to heat or to cool the space as desired.
The Lodge patent, U.S. Pat. No. 3,407,620 describes a system for heating and cooling using a recirculating water loop. Heating is supplied by a standard heater using combustible fuel, and cooling is provided by a cooling tower. Although the patent represents the system as a heat pump, it is not a heat pump by the usual thermodynamic definition.
The La Fleur patent, U.S. Pat. No. 3,355,903, describes a closed reverse-Brayton-cycle refrigeration system to provide refrigeration for air liquefaction. Repetitive stages of compression and cooling are employed.
A heat-actuated space conditioning system utilizing a Brayton engine is described in an article entitled "Light Commercial Brayton/Rankine Space Conditioning System" by David Friedman, beginning at page 172 of the August, 1977 Proceedings of the 12th IECEC (Intersociety Energy Conversion Engineering Conference). This article describes a Brayton cycle system utilizing a combustor driving a turbo-compressor, the latter being magnetically coupled to a second compressor in an associated Rankine cycle system.
Such systems as are known may provide improved efficiency over the standard air conditioning system including a furnace for heating and a refrigeration type air conditioner for cooling, but the cost of such a heat pump system is generally substantially greater because of the increased complexity. However, with the recent substantial increases in the cost of fuel, it becomes more worthwhile, indeed essential, to develop systems of improved efficiency.
The present invention is directed to the provision of a simplified heat pump system of improved efficiency for selectively heating or cooling a residential space in a temperate zone region where extreme low and high temperatures are seldom encountered.