GB2039027A

GB2039027A - Thermal energy store

Info

Publication number: GB2039027A
Application number: GB7840380A
Authority: GB
Original assignee: Neal W E J; PABONDIAZ M
Current assignee: Neal W E J; PABONDIAZ M
Priority date: 1978-10-12
Filing date: 1978-10-12
Publication date: 1980-07-30

Abstract

A low loss thermal store is used in conjunction with a heat pump or heat pumps and incorporated in a system for space heating or cooling and water heating. The store comprises two or more regions or zones of different temperature t1...t3 in which heat pumping normally takes place from the outer zone which is at a lower temperature by means of evaporators or condensers C1...C3 of a heat pump. The store can be charged by any form of heat derived from any source. Diagrams illustrate three of ten possible modes of operation. Two possible examples of store design are illustrated, one incorporating heat exchangers within the store and the other with a particular flow pattern through the store with heat exchangers outside the store. The latter design is shown incorporated in a complete heating and cooling system. One diagram incorporates a cooling coil to extract heat under extreme conditions to form ice. <IMAGE>

Description

SPECIFICATION A low loss thermal energy store incorporating heat pumping, for use with water and space heating and air conditioning systems DESCRIPTION The thermal store may be of any shape, e.g.

cubic, cylindrical or spherical, depending on the particular application or space available. The store would comprise two. or more regions or zones of different temperatures with thermal insulation at some of the boundaries between regions or zones and between part of a zone and ambient surroundings. The main storage medium could be water or any other liquid and part or alt of some zones could contain a salt having a phase change at the appropriate zone temperature. The innermost region or zone of the store would be at the highest temperature. The outer surface of the outer zone would be in contact with ambient air or ground. The various regions of the store at the different temperatures would be in contact either directly or indirectly with an evaporator or condenser of a heat pump depending on its mode of operation.The store itself could be charged directly or indirectly from any source of heat such as solar panels, heat from burning fossil fuel, resistive heating or from a condenser of a heat pump upgrading heat from ambient air or any solar assisted heat pump system. Heat leaking from zones of the store at higher temperature to zones at lower temperature will be used to evaporate freon in evaporator coils located in the lower temperature zones. One advantage of using a heat pump for retrieval of heat from store is that for a given thermal output requirement the store vplume is reduced depending on the coefficient of performance in the heating mode C.O.P. (H).

0R = Q,+W Heat required = Heat stored + Work done by compressor QR/\N = C.O.P. (H) where QR = heat required Q5 = heat stored Figures 1, 2 and 3 illustrate the principle of the invention for a store with three temperature regions t1, t2 and t3 where t1 > t2 > t3. As shown C1, C2 and C3 are coils forming either evaporators or condensers of a heat pump depending on whether heat is being extracted from a region of store or whether the region is being charged.

As shown in Fig. 1, cur is the condenser in zone 1. The central region is charged by extracting heat from ambient air (0,) and condensing heat Q1 in region 1. By suitable valving (Fig. 2) regions 1 and 2 could be charged. As an alternative (Fig. 3) C3 could act as the evaporator and C, the condenser.

The other parts of the diagram show the aspects of a water heating and space heating system which could be used in conjunction with the heat pump and storage system where heat is abstracted from the store by pumping liquid (water) through heat exchange coils C4 and C5 in regions 2 and 1 from region 3 and returning to 3 after passing through the liquid/air heat exchanger C6 for domestic or commercial space heating. Fig.

4 shows a zone arrangement for a cylindrical thermal storage system based on the principle outlined for use in conjunction with a solar panel.

CLAIMS 1. The invention is a low heat loss thermal energy store for use in conjunction with a heat pump or heat pumps to provide (a) heat for a hot water supply and/or space heating (b) space cooling and heat for a hot water supply.

2. The thermal store as claimed in claim 1 could be comprised of several temperature zones separated by insulating material with the zone of maximum temperature at the centre.

3. The thermal store as claimed in claim 1 can be charged: (a) by operating the heat pump(s) in claim 1 as an air to liquid system where heat is extracted from external ambient air (or from an environment to be air conditioned) at the evaporator of the heat pump, and heat rejected to a liquid at the condenser -- which in most cases would be water but could be a mixture of liquids or a solution.

(b) by heat obtained from a solar (air or liquid) collector panel.

(c) by a series or parallel combination of a heat pump and solar (air or liquid) collector panel.

(d) by electrical resistive heating.

(e) By any form of heat derived from any source.

4. The stored energy in the thermal store as claimed in claim 1 could be in the form of sensible heat with, for example, water as the storage medium but could include latent heat storage or a combination of sensible and latent heat storage.

5. The thermal store as claimed in claim 1 could be incorporated in a heating, cooling or air conditioning system.

6. Heat for space heating (at adequate store temperatures) may be extracted from the thermal store in claim 1 by circulating a fluid through a heat exchanger (or exchangers) in the store and through a heat exchanger (or exchangers) external to the thermal store.

7. Heat for hot water and/or space heating may be extracted from the thermal store in claim 1 by operating a heat pump or heat pumps as a liquid to air or liquid to liquid system with the evaporator extracting heat from a zone of the store where the temperature is too low for the operation as in claim 6.

8. In a thermal store as in claim 1, where water is used as the storage medium, in extreme conditions during periods of low ambient temperatures (when heating loads are high) ice could be produced in one or more zones of the store when operated as in claim 7.

9. Heat leakage in the thermal store in claim 1 would normally be from zones at higher temperature to the extremities and some of this heat leakage would be recovered by the heat pump operation as in claim 7 when heat is extracted from the zone or zones at the extremities.

10. When all zones or one zone of the thermal store as in claim 1 is below the temperature of an environment, cooling of the environment can be effected by circulating a fluid through a heat exchanger (or exchangers) in the thermal store and through a heat exchanger (or exchangers) external to the thermal store.

11. When the thermal store in claim 1 is comprised of water, the heat exchanger (or exchangers) within the store can be excluded provided suitable flow paths through the store are provided and heat exchange provided between the store water and the appropriate evaporator(s) or condenser(s) of the heat pump or heat pumps.

12. The thermal store as claimed in claim 1 would be suited for a range of situations such as for example in domestic, commercial, agricultural and industrial applications.

13. Up to ten modes of operation (for water heating and/or space heating or cooling) are possible when the store in claim 1 is used in conjunction with a heat pump or pumps.

New claims or amendments to claims filed on 13 Feb 80.

Superseded claims 1-13 (all).

New or amended claims

Claims

1. A thermal energy store having an inner zone and an outer zone, each zone containing a thermal energy storage medium, wherein the thermat energy storage medium in the outer zone is at a temperature which is nearer to ambient temperature than the thermal energy storage medium in the inner zone.

2. A thermal energy store as claimed in claim 1, further including at least one intermediate zone containing a thermal energy storage medium which is at a temperature between the temperatures of the media in the inner and outer zones.

3. Athermal energy store as claimed in claim 1 or 2, wherein thermal insulation is disposed between the zones.

4. A thermal energy store as claimed in any preceding claim, wherein the temperatures of the thermal energy storage media are above ambient temperature.

5. A thermal energy store as claimed in any preceding claim, wherein the thermal storage media are liquids.

6. A thermal energy store as claimed in any preceding claim, wherein heat exchangers are disposed in the zones for supply of thermal energy to and/or for the removal of thermal energy from the zones.

7. A thermal energy store as claimed in any preceding claim, wherein at least one of the thermal energy storage media is a medium which experiences a phase change at the temperature of the zone.

8. A thermal energy store substantially as hereinbefore described with reference to the accompanying drawings.

9. A thermal energy transfer system comprising a thermal energy store as claimed in any preceding claim, means for selectively supplying thermal energy to the store, and at least one heat pump for selectively removing thermal energy from the store.

10. A system as claimed in claim 9, wherein the means for selectively removing thermal energy from the store is arranged to remove thermal energy from the outer zone via the other zone(s).

1 A system as claimed in claim 10, wherein a heat exchanger is provided in the or each of said other zone(s) and Is in heat exchanger relationship with the thermal energy storage medium in that zone, and the thermal energy is removed from the outer zone through said heat exchanger(s).

12. A system as claimed in claim 9, 10 or 11, wherein a heat pump is provided for selectively transferring heat energy from the outer zone to the inner zone.

13. A system as claimed in claim 9, 10, 11 or 12, wherein the means for selectively supplying thermal energy to the store includes a heat pump.

14. A thermal energy transfer system substantially as hereinbefore described with reference to the accompanying drawings.