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
1999-07-29
2000-11-28
Nguyen, Hoang
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...
60517, F15B 2910
Patent
active
061518964
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a heating installation for area heating, comprising a burner and a Stirling engine thermally coupled to the burner, wherein the Stirling engine comprises a closed pressure vessel containing a working gas, the pressure vessel comprising a first hot chamber and a first cold chamber, and, adjoining the latter, a working chamber containing a piston element, as well as a second hot chamber and a second cold chamber, the hot chambers, the working chamber and the cold chambers being in fluid communication with one another, the pressure vessel being provided, at the level of the hot chambers and the cold chambers, with, in each case, an external heat exchanger, the first cold chamber and the second hot chamber being connected via their respective heat exchangers to a hot water system.
In IEA Heat Pump Centre Newsletter Vol. 13, No. 4, 1995, pages 31-34, a duplex Stirling heat pump system is described in which a free-piston Stirling engine drives a Stirling heat pump. In this system a power piston is replaced by a resonating gas column whereby the engine piston seal can be avoided. In the first hot chamber of the Stirling engine temperatures are up to 600.degree. C.-800.degree. C. The first cold chamber of the Stirling engine generates heat at a temperature of 40-60.degree. C. The second cold chamber, which is the cold chamber of the Stirling heat pump draws heat from the ambient air, water or ground at temperatures between -20.degree. C. and 20.degree. C. which heat is ejected through the heat exchanger of the hot chamber of the Stirling heat pump at temperatures between 40 and 60.degree. C.
European Patent Application EP-A 0 457 399 discloses a combined heat and power plant for private residences, in which a Stirling engine is used to generate electricity. The heat released by the relatively cold chamber of the Stirling engine and the hot exhaust gases are used for heating water for, for example, tap water or for heating air. A net efficiency of 85% or higher can be achieved with a system of this type.
It is an object of the present invention to provide a heating installation based on a Stirling system of the above described type wherein a high coefficient of performance can be obtained, which is easy to install and to maintain and which can be operated at various different conditions of heat demand.
Thereto a heating installation according to the present invention is characterized in that the hot water system comprises two heat exchangers coupled to the first cold chamber and the second hot chamber respectively and a third heat exchanger which is thermally coupled to the exhaust gases of the burner.
By heating the cold water through the heat exchangers, including heat exchange with the exhaust gases, a high coefficient of performance can be obtained. The coefficient of performance, or "COP" is defined herein as the total heat produced by the complete system divided by the enthalpy of the input fuel.
In one embodiment, the three heat exchangers are connected in series, the cold water being successively heated to increasingly high temperatures. When the cold water arrives at the first heat exchanger that is connected to the hot chamber of the Stirling heat pump, with a temperature of 60.degree. C. and leaves the heat exchanger of the exhaust gases with a temperature of 80.degree. C., a COP of 1.38 can be obtained. The system wherein cold water arrives at the first heat exchanger with a temperature of 10.degree. C. and leaves the heat exchanger of the exhaust gases at a temperature of 60.degree. C. has a COP of 1.72. In this latter case the exhaust gasses are condensed to only a minor extent. However, as the temperature lift of the Stirling heat pump is relatively small, the overall efficiency is increased.
Since the COP values of the Stirling heat pump are less sensitive for thermal conditions of the external heat source than electric heat pumps, integration of the Stirling engine and the Stirling heat pump will give the possibility to maximize the overall system COP. This is achieved by b
REFERENCES:
patent: 3458995 (1969-08-01), Heffner et al.
patent: 4723410 (1988-02-01), Otters
patent: 4998460 (1991-03-01), Wolfs et al.
J.P. Budliger, "Stirling Technology for the Home", IEA Heat Pump Centre Newsletter, vol. 13, No. 4, 1995, pp. 31-34.
Korobitsyn Michail Aleksandrovitsj
Penswick Barry
Ribberink Johan Sjoerd
Veringa Hubertus Johannes
Nguyen Hoang
Stichting Energieonderzoek Centrum Nederland
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