GB2245056A

GB2245056A - Solar heating systems

Info

Publication number: GB2245056A
Application number: GB9010142A
Authority: GB
Inventors: Brian Arthur Frederic Withyman
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-05-04
Filing date: 1990-05-04
Publication date: 1991-12-18
Also published as: GB9010142D0

Abstract

A primary solar heat collecting circuit 21 comprises a solar heat collector 14 connected to a heat exchanger 16 by a flow line 18 and return line 20, a circulating pump 22, spring-loaded non-return valves 24, 25, an expansion vessel 28, a pressure gauge 30, a safety valve 33 and a water heating cylinder 34 controlled by a valve 35. A secondary, heat-distribution circuit (shown in chain-dot lines) 35 comprises the heat-exchanger 16, an auxiliary heater 37 and one or more heat-storage panels 38. Each circuit contains under pressure of 10-14 psi a circulating fluid such as a liquifiable gas eg freon (RTm) or an oil. An electronic control unit 40 is connected to temperature sensors 44, 46, 48 the circulating pump 22 and the auxiliary heater 37. <IMAGE>

Description

SOLAR HEATING SYSTEMS This invention relates to solar heating systems and particularly, but not exclusively, to systems for heating houses and other accommodation.

It is an aim of the present invention to improve on the efficiency and capital costs of prior art systems.

According to a first aspect of the present invention there is provided a solar heating system for heating, for example a dwelling house, the system comprising a solar collector and heat-exchanger, heat-storage or heat-radiating means arranged on a circuit for the circulation, preferably under pressure, of a heat-transfer medium, said medium being a fluid which, under the conditions of operation, is a liquid having a boiling point higher than 10000. Preferably the medium has a boiling point of from 150 to 200"C and a freezing point below -50 C, and is also used on a secondary circuit.

According to a second aspect of the present invention there is a provided a solar heating system for heating, for example1 a dwelling house, the system comprising a solar collector connected by a primary circuit to the input of a heat exchanger, the output of which is connected by a secondary circuit to one or more heat-storage radiators. Preferably an indirect hot water cylinder is incorporated in the secondary circuit. The radiators thus act in a manner which is the reverse of that of electric night-storage heaters, absorbing at during the day and giving it out at night.

Conveniently the heat-transfer medium used in the primary and/or secondary circuit is according to the first aspect of the invention.

Although the invention may be carried out in a variety of ways one particular embodirnent there will now be described, by way of example, with reference to the accompanying drawing whicn is a diagram cf a domestic solar heating system according to the invention.

As shown in the drawing a house 1 has a roo 12 on which is mounted a solar collector 14, which is fitted with an air vent 15 and connected to a heat exchange 1t by a solar flow line 18 and solar return line 20, constituting a primary, solar collecting circuit 21. The fluid circulating under pressure in the circuit 21 may be, for example, a liquefiable gas such as a Freon or an oil known as dielectric 180".The collector 14 is preferably of the type which allows individual tubes to be replaced without disturDino the primary circuit 21. Incorpsrated in the primary circuit 21 are a circulating pump 22, spring-loaded non-return valves 24, 26, an expansion vessel 28, a pressure gauge 301 a stop-cock 32 for filling and draining down, a "Ball-o-Fix" valve 33 to provide a safety back-up, and a water heating cylinder 34 controlled by a three-way valve 35.

Indicated in chain-dot lines is the secondary, heat-distribution circuit 36, which uses a similar heat-transfer medium and which runs from the heat-exchanger 16 through an auxiliary heater 37 and one or more heat-retention panels 38 before returning to the heat-exchanger 16. The panels 38 are filled with a material having a high specific heat, such as brick.

The sensing and control system 39 is shown in dashed lines and is based on an electronic control unit 40 supplied from the mains through a fused switch 42, and connected to collector temperature sensors 44, 46; a temperature sensor 48 in the return of the secondary circuit 36; and a control unit for the circulating pump 22 and for the auxiliary heater 37. The control unit 40 is arranged to operate the pump 22 (which may if desired be powered by solar-generated current) in accordance with a signal indicative of the difference between the temperature sensed by the sensors 44, 46 and the sensor 48. A readout of the sensed temperatures is given by a digital display unit 50.

Due to the pressure conditions (10 - 14 psi) and the nature of the heat transfer medium used in the primary circuit 21, high operating temperatures of from 1500 to 200"C may be employed with a consequent increase in heat-transfer efficiency. Moreover, the greater efficiency in turn allows a smaller volume of fluid (for example, 2 gallons) to be employed to transfer the same amount of heat, thus reducing the energy consumed by the circulating pump 22.

As the present invention allows a large water-filled, heat-storage tank, which is a common feature of prior art systems, to be dispensed with the volume of fluid required in the secondary circuit is reduced to a minimum and the efficiency of that circuit increasec.

Claims

CLAIMS:

1. A solar heating system comprising a solar collector and heat-exchanger, heat-storage or heat-radiating means arranged on a circuit for the circulation of a heat-transfer medium, said medium being a fluid which, under the conditions of operation, is a liquid having a boiling point higher than 100"C.

2. A solar heating system comprising a solar collector connected by a primary circuit to the input of a heat exchanger, the output of which is connected by a secondary circuit to one or more heat-storage radiators.

3. A solar heating system as claimed in Claim 2, wherein an indirect hot water cylinder is incorporated in the secondary circuit.

4. A solar heating system as claimed in Claim 1, 2 or 3, which contains a medium which has a boiling point of from 150 to 2000C and a freezing point below -50 C.

5. A solar heating system as claimed in Claim 4, wherein said medium is also used in a secondary circuit.

6. A solar heating system as claimed in any preceding claim, which includes an electronic control unit connected to at least one sensor for sensing the temperature of the solar collector, a temperature sensor in the return portion of the secondary circuit; and a control unit for the circulation circuit.

7. A solar heating system substantially as hereinbefore described with reference to the accompanying drawing.

8. A method of heating wherein a solar heating system as claimed in any preceding claim is used.