Heating systems – Plants
Patent
1993-12-29
1996-07-16
Bennett, Henry A.
Heating systems
Plants
237 123A, 34 86, H02K 900, F25B 2700, F24H 302
Patent
active
055359442
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a combined heat and power system for generating electrical power and heat for a building.
A conventional low pressure hot water (LPHW) combined heat and power system comprises a gas engine driving an electric generator which provides a portion of the power required by a building. Waste heat from the combustion process in the engine is collected from the engine cooling system and exhaust system and transferred to a low pressure hot water system by way of separate heat exchangers. The LPHW is pumped around the building to provide hot water for radiators, domestic hot water systems and possibly to air handling unit heating coils. Such a system is used in, for example, leisure centres and swimming baths, hotels, hospitals and sheltered housing.
However, one of the disadvantages of a conventional combined heat and power system is the difficulty of recovery of waste heat from the engine and generator surfaces which prevents the efficiency of the system rising above about 80%.
The present invention seeks to provide an improved system for providing electrical power and heating for a building.
Accordingly, the present invention provides a system for providing electrical power and heating for a building, comprising:
a housing having an air inlet and first outlet for connection to a ventilation air system of the building and wherein the housing contains:
an electrical generator for generating electrical power; power drive means for driving said generator;
means for drawing recirculating air from said housing first inlet to said housing air outlet past said electrical generator and drive means whereby said air is heated by waste heat from said generator and said drive means;
wherein said housing has a second inlet downstream of said drive means for inlet of external air and said adjusting means comprising means for mixing said recirculating air with said external air to adjust the temperature of recirculating air passed to said first outlet; and
wherein said housing has a second outlet downstream of said drive means for exhausting recirculating air to atmosphere, and said mixing means comprises exhaust damper means for controlling the passage of recirculating air through said second outlet.
and adjusting means downstream of said drive means for adjusting the temperature of said air;
and wherein said housing has a second inlet downstream of said drive means for inlet of external air and said adjusting means comprising means for mixing said recirculating air with said external air to adjust the temperature of recirculating air passed to said first outlet.
The phrase "external air" as used herein refers to air which does not form part of the recirculating air.
The term "gas engine" as used herein refers to any suitable type of engine, e.g. internal combustion engine or gas turbine engine.
In a preferred embodiment of the invention the drive means has a cooling system including a heat exchanger for transferring heat from the cooling system to air flowing from the housing inlet to the outlet. The engine is a gas engine and has a further heat exchanger in an exhaust gas system of the engine for transferring heat from exhaust gases of the engine to air passing from said housing inlet to said outlet. It will be appreciated that the heat exchangers may be placed in parallel with reference to the air flow or in series and may be provided with respective air bypass arrangements to allow the flow of air partially or completely to bypass either one or both of the heat exchangers.
To further extract heat from the exhaust gas, the path of the exhaust system may be routed back through the engine/generator housing where additional extended surface heat exchangers may be installed.
The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a conventional low pressure hot water combined heat and power system; and
FIG. 2 is a schematic diagram of a preferred form of combined heat and power system accord
REFERENCES:
patent: 2465184 (1949-03-01), Alderman
patent: 3231986 (1966-02-01), Touton
patent: 4240581 (1980-12-01), Fowler
Bennett Henry A.
Gravini Steve
Tilehouse Group PLC
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