Power plants – Motor operated by expansion and/or contraction of a unit of... – Unit of mass is a gas which is heated or cooled in one of a...
Patent
1984-10-29
1986-11-18
Husar, Stephen F.
Power plants
Motor operated by expansion and/or contraction of a unit of...
Unit of mass is a gas which is heated or cooled in one of a...
60526, F02G 104
Patent
active
046228136
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention is directed to novel forms of a hot gas engine and heat pump in which heat to be converted to work or to be pumped is applied external to cylinders containing the working gas. In particular, the present invention is directed to improved forms of a Stirling cycle engine and heat pump. The term "heat pump" is used in its generic sense designating a device which may be used either for heating or refrigeration.
BACKGROUND ART
The present invention is directed to a novel machine utilizing a modified "Stirling cycle". The first Stirling cycle machine was invented in 1816 by Robert Stirling. It ran as an engine, turning heat into mechanical energy. Subsequent development has shown that Stirling cycle machines can also be run in reverse, being driven by mechanical energy to act as heat pumps in refrigeration applications. Practical problems, discussed below, have prevented Stirling cycle machines from coming into widespread use in any of their potential applications.
Conventional Stirling cycle machines operate with working gas such as air, hydrogen or helium. When the Stirling cycle machine is run as an engine, the working gas is compressed while being cooled in the cold space of the engine during the "compression" phase of the cycle. The working gas is then permitted to expand into the hot space of the engine where it is heated as it expands during the power stroke phase of the cycle. The working gas is then transferred out of the hot space and into the cold space of the engine at constant volume during the "regeneration" phase of the cycle. The cycle then repeats.
The expansion of the working gas in the hot space of the Stirling cycle machine during the power stroke of the cycle produces work when the machine is run as an engine. The compression phase of the cycle absorbs work when the Stirling machine is run as an engine, but it absorbs less work than is generated in the expansion phase of the cycle. The excess work is absorbed in part by mechanical and gas friction (including that involved in the transfer/regeneration phase.) The remainder of the work is useful work.
When run as a heat pump, a Stirling cycle machine requires more energy to compress the working gas during the compression phase of the cycle than is returned during the expansion phase of the cycle because the part of the machine that is absorbing heat from the surroundings (i.e., the expansion space) is colder than the part of the machine where the working gas is compressed (i.e., the compression space).
The present invention is described below as an engine, with reference to the compression space as the "cold space" and the expansion space as the "hot space". If the machine were operated as a refrigerator (heat pump) rather than as an engine, temperatures of the compression and expansion space would be reversed. Both when the invention is used as an engine and as a heat pump, gas entering the expansion space is subjected to external heating, and gas entering the compression space is subjected to external cooling.
Numerous machines embodying variants of the Stirling cycle have been described. (See Walker, Stirling Engines, Claredon Press (1980); Stirling Engine Design and Feasibility for Automotive Use, Collie ed., (Noyes Data Corp. 1979).
The theoretical advantages of the Stirling cycle engines are considerable. They are, in theory, highly efficient. Also, since their heat sources are external to the working gas, some of the air pollution problems associated with internal combustion engines can be avoided. Since fuel for a Stirling cycle engine can be burned steadily at atmospheric pressure rather than exploded at high temperature and pressure, Stirling cycle engines are comparatively quiet. They may be powered by any available source of heat and can thus operate with any type of fuel, including solar heat, geothermal heat or heat from nuclear fission or fusion.
However, a number of practical problems have prevented commercial use of Stirling cycle machines. Those problems include the following:
(1) The
REFERENCES:
patent: 2560987 (1951-07-01), Rinia et al.
patent: 3457722 (1969-07-01), Bush
patent: 4241580 (1980-12-01), Kitzner
Husar Stephen F.
Limbach Karl A.
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