Domestic combined heat and power unit

• US 20050052029A1
• Filed: 12/18/2002
• Published: 03/10/2005
• Est. Priority Date: 12/20/2001
• Status: Active Grant

• Current Assignee: BDR Thermea Group BV (Stichting Aandelen Remeha)
• Original Assignee: Microgen Engine Corporation Holding BV
• Inventors: Allederidge, Heather, Clark, Anthony David, Aldridge, Wayne Kenneth, Francis, George McChesney, Roberts, Graham Richard
• Granted Patent: US 7,459,799 B2
• Time in Patent Office: Days
• US Class Current: 290/2
• CPC Class Codes: F02G 1/043 the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
• CPC Class Codes: H02J 9/08 requiring starting of a prime-mover
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]

Abstract

A domestic combined heat and power (dchp) unit includes a Stirling engine (1) to provide heat for a domestic dwelling along with a source of electrical power. Under normal operation, the dchp is supplied with power from the national grid. When there is an interruption in the mains power from the grid, the dchp switches into a grid independent mode wherein power is generated by the dchp and is supplied to a controller (26) and to a water pump so as to maintain integrity of heat supply to the dwelling; the remaining power after that is supplied to selected domestic electrically powered equipment such as lights or television sets. The invention also discloses methods for black start of the dchp during a mains power loss, and also modification of the operating voltage on start up of electrical equipment during a power loss, to prevent the Stirling engine stalling.

Claims

1. A domestic power system to provide the heat and electrical power requirements in a domestic dwelling, the system comprising a connection to a mains power supply which satisfies at least part of the domestic electrical power requirement during normal operating conditions;

a domestic combined heat and power unit with a combustible fuel supply and which produces electrical power output and heat output which satisfies at least a part of the domestic heat requirement, the unit being operable in the absence of the mains power supply;

means for detecting interruption of the mains power supply; and

means for automatically connecting the electrical power output from the domestic combined heat and power unit, in the absence of mains power, so as to provide a backup power supply for selected electricity consuming apparatus, with a lower electrical power demand than the total domestic electrical power requirement in the absence of mains power.

2. A system according to claim 1, wherein the domestic combined heat and power unit comprises a Stirling engine comprising a burner to input heat energy into the engine head to drive a reciprocating member, the reciprocating member producing electrical output via an alternator;

and a start-up system including control means for controlling the start-up of the unit, an ignitor to ignite the burner, a pulse generator to supply an electrical pulse to the generator to set the reciprocating member in motion when the control means determines that the engine head has reached a threshold temperature, and a local limited supply of electrical power to power the control means, ignitor and pulse generator during the start-up operation.

3. The system of claim 1, further comprising a power output limiter arranged to limit the power output of the domestic combined heat and power unit to a value equal to or less than a predetermined maximum available power output thereof, during the absence of mains power.

4. The system of claim 3, wherein the power output limiter is a controller arranged, during the absence of mains power, to control the instantaneous peak voltage to a value less than a normal operating voltage, when the current to be drawn by a load exceeds the maximum current that could be drawn from the domestic combined heat and power unit at the said normal operating voltage provided thereby.

5. A system according to claim 4, where the controller is an impedance conversion wave controller.

6. The system of claim 4, further comprising a timer arranged to determine the amount of time over which the current to be drawn by the said load exceeds the said maximum current that could be drawn at the said normal operating RMS voltage, the power output of the domestic combined heat and power unit being isolated from use by the said selected electricity consuming apparatus when the determined time exceeds a predetermined threshold.

7. A system according to claim 1, wherein the combustible fuel supply is the domestic gas supply.

8. A system according to claim 1, wherein a domestic combined heat and power unit comprises a Stirling engine.

9. A system according to claim 8, wherein the Stirling engine is a linear free piston Stirling engine.

10. A system according to claim 1, wherein the selected electricity consuming apparatus are entirely separate components from those normally supplied in a domestic dwelling.

11. A system according to claim 1, wherein the selected electricity consuming apparatus are a subset of those normally supplied in the domestic dwelling, and wherein the system is provided with means to selectively disconnect various electricity consuming apparatus in the absence of mains power.

12. A system according to claim 1, wherein the means for detecting interruption of the mains power supply is also able to detect when the main voltage or frequency of the mains power supply are outside acceptable levels.

13. A system according claim 1, further comprising an electrical sink to consume excess electricity.

14. A system according to claim 13, wherein the electrical sink is provided in the form of an air or water cooled resistor.

15. A system according to claim 1, further comprising a heat sink to consume excess heat.

16. A system according to claim 15, wherein the heat sink is a supplementary airstream which is able to dissipate heat output from the domestic combined heat and power unit.

17. A system according to claim 15, wherein the heat sink is a radiator of a domestic central heating system.