GB2131155A

GB2131155A - Solar heating

Info

Publication number: GB2131155A
Application number: GB08233710A
Authority: GB
Inventors: Sabet Faramarz Mahdjuri
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-11-26
Filing date: 1982-11-26
Publication date: 1984-06-13
Also published as: GB2131155B

Abstract

A solar heating system comprises a water storage tank (7) and an array of solar collectors (1), each comprising an elongate, evacuated, substantially cylindrical, transparent envelope and an absorber plate (2). Each absorber plate is thermally conductively connected to the evaporation zone of a heat pipe (3) which extends through the end of the transparent envelope so that its condenser zone is situated in the tank. <IMAGE>

Description

SPECIFICATION Solar hot water system The invention relates to a solar collector combined with a storage tank, called Solar Hot Water System. The system comprises of an absorber plate which absorbs solar radiation and converts it to heat and which is thermally in connection to the evaporated zone of a heat-pipe, the absorber plate and the evaporator zone of the heat-pipe being enveloped by a transparent envelope in which subatmospheric pressure prevails, the heat-pipe passes through an end face of the transparent envelope wherein the condenser zone of the heat-pipe which is situated outside the envelope, the heat-pipe containing a working medium having a critical temperature between 65 and 100 C and an insulated storage tank situated above the collector, which contains water to be heated, wherein the condenser zone of the heat-pipe in the storage tank is located and is in direct contact with the water.

The solar collector of the described kind is known from GB Patent 2023804 or GB Patent Application 7917876. In this type of solar collector the heat absorbed by the absorber is transferred to the heat-pipe. The working medium in the heat-pipe transports the heat to the condenser zone of the heat-pipe by way of an evaporation/condensation cycle. Finally, the condenser zone gives off the heat to the medium which being circulated (pump) to the storage tank where the heat being transferred to water in the tank via a heat exchanger.

A suitable heat exchanger between the condenser zone of the heat-pipe and the medium in the circulation system, a pump for the circulation and an efficient heat transfer between the heat exchanger in the storage tank and the water in the tank are required. Furthermore, a complicated control system is needed to activate the pump during the sunny hours. These facts are complicating the solar system and making the installation difficult and less economical.

One objective of the present invention is to provide a solar collector system which can be very readily built without it being necessary to use a recirculating pump, control unit and heat exchanger in the storage tank. A solar hot water system with integrated storage tank without using pump control unit and heat exchanger is known. Hereby the collector simply made out of an absorber plate covered with a glass pane, the absorber plate is in thermal contact with a water tube, the water tube on the top of the collector is connected to top of the storage tank and the bottom part of the water tube is connected to the lower part of the storage tank. The heat transfer occurs simply through thermal syphon effect. The system has frost problem during the winter and boiling problem in the hot summer days, which would require safety measures.

The objective of present invention is to provide a solar hot water system which does not require recirculating pump, control unit, heat exchanger in the storage tank and will not be subject to frost in the winter and no danger of overheating in hot summer days.

According to the present invention there is provided a solar hot water system comprising of an absorber plate which absorbs solar radiation and converts it to heat and which is thermally in connection with the evaporator zone of a heat-pipe, the absorber plate and the evaporator zone of a heat-pipe being enveloped by a transparent envelope in which subatmospheric pressure prevails, the heat-pipe passes through an end face of a transparent envelope wherein condenser zone of the heat-pipe, which is situated outside the envelope, the heat-pipe containing a working medium having a critical temperature between 65 and 1 OO"C and insulated storage tank situated above the collector which contains water to be heated wherein the condenser zone of the heat-pipe in the storage tank is located and is in direct contact with the water.The heat transfer medium of the heat-pipe is characterised to be one of the following medium: CRIT. TEMP. ("C) FREON* 1381 (CBrF3) 67 FREON* 502 (CHF2CI + CCPF2CF3) 82 FREON* 22 (CHF2CP) 96 PROPANE (C3H8) 96.8 * FREON is a trade mark The heat transfer capacity of the heat-pipe is zero at the critical temperature and has a substantial value below the critical temperature. This results in interruption of the heat from the collector to the storage tank, when the watertemperaure approaches the critical temperature of the used medium in the heat pipe.

Since the freezing point of the used medium is lower than -50 C and the heat transfer in the heat-pipe, without wicks, is one-directional - i.e. from bottom to the top where the condenser is situated - the heat-pipe can not extract the heat from the storage tank and the insulation of the storage tank will be the only parameter which will be subject to freeze the water in the storage tank in winter time. It is obvious that the insulation of the tank can be determined according to the climate conditions.

The invention described in detail hereinafter with reference to the accompanying drawing which diagrammatically shows two types of examples.

The solar hot water system shown comprises a solar collector (1), absorber plate (2), heat-pipe (3), evaporator zone of the heat-pipe (4), transparent envelope - tube - (5), condenser zone of the heat-pipe (6), storage tank (7), insulation of the storage tank (8), sealing cap or nut (9), sealing gasket to seal the inserted condenser zone against the opening of the storage tank (10).

CLAIMS (Filed on 17/11/83) 1. A Solar Hot Water System comprising a water storage tank and an array of evacuated solar tubes each comprising an elongated, evacuated, substantially cylindrical, transparent envelope and an absorber plate which absorbs solar radiation and converts it into heat, characterised in that the mentioned absorber plate is thermally, conductively, connected to the evaporation zone of the heat pipe and the heat pipe being past vacuum sealed through the end face of the transparent envelope wherein the condenser zone of the heat pipe is situated and the mentioned condenser of the solar tubes are located at the lower section and inside the storage tank in direct heat exchange contact with the water and the heat transfer from the evaporator of the heat pipe being interupted art a well defined temperature not exceeding 100 C.

2. Solar Hot Water System as claimed in Claim 1 characterised in that the evacuated solar tubes are easily removable assembled to the storage tank.

3. Solar Hot Water System as claimed in Claims 1 and 2 characterised in that the evacuated solar tubes are being assembled and sealed to the storage tank by means of a retaining cap and sealing washer.

4. The Solar Hot Water System as claimed in Claims 1 and 2 characterised in that the evacuated solar tubes are being assembled and sealed by means of a compression fitting.

5. The Solar Hot Water System as claimed in Claims 1 - 4 characterised in that the working fluid of the heatpipe having a critical temperature not exceeding 100" C.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The invention described in detail hereinafter with reference to the accompanying drawing which diagrammatically shows two types of examples. The solar hot water system shown comprises a solar collector (1), absorber plate (2), heat-pipe (3), evaporator zone of the heat-pipe (4), transparent envelope - tube - (5), condenser zone of the heat-pipe (6), storage tank (7), insulation of the storage tank (8), sealing cap or nut (9), sealing gasket to seal the inserted condenser zone against the opening of the storage tank (10). CLAIMS (Filed on 17/11/83)

1. A Solar Hot Water System comprising a water storage tank and an array of evacuated solar tubes each comprising an elongated, evacuated, substantially cylindrical, transparent envelope and an absorber plate which absorbs solar radiation and converts it into heat, characterised in that the mentioned absorber plate is thermally, conductively, connected to the evaporation zone of the heat pipe and the heat pipe being past vacuum sealed through the end face of the transparent envelope wherein the condenser zone of the heat pipe is situated and the mentioned condenser of the solar tubes are located at the lower section and inside the storage tank in direct heat exchange contact with the water and the heat transfer from the evaporator of the heat pipe being interupted art a well defined temperature not exceeding 100 C.