British Gas Plc

Microgen Energy Limited

Graham Richard Roberts

Barry Leonard Price

David Anthony Clark

Heather Allderidge

Wayne Kenneth Aldridge

George McChesney Francis

Andrew Jonathan Cole

David Richard Wightman

A domestic combined heat and power (dchp) unit includes a Stirling engineto 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 controllerand 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.

Domestic combined heat and power unit

A meter to measure the volumetric flow rate of a liquid, for example water, is formed with a pipe forming a liquid flow path containing a low power electrical heater. A first temperature sensor measures the temperature T of the liquid adjacent to an upstream end of the heater and a second temperature sensor measures the temperature T.sub.2 of the liquid adjacent to a downstream end of the heater. The heater adds heat power of a value P to the liquid. A control arrangement comprising a computer means calculates the flow rate Q using the expression ##EQU1## where ST.sub.1 and DT.sub.1 are respectively the specific heat capacity of the liquid and the density of the liquid at the temperature T.sub.1 measured by the first sensor.

Liquid metering

Apparatus and method for measuring heat power consumed in or extracted

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Hatton, United Kingdom

Graham Richard Roberts