GB2552325A

GB2552325A - Thermal store arrangement

Info

Publication number: GB2552325A
Application number: GB1612413.3A
Authority: GB
Inventors: Bursell Marley
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-07-18
Filing date: 2016-07-18
Publication date: 2018-01-24
Also published as: GB201612413D0

Abstract

A thermal store arrangement (15, Fig. 1) has a thermal store 16 having a volume suitable for receiving a thermal store medium. The thermal store 16 incorporates a main heat exchanger 25 with an inlet 27 and an outlet 28. Thermal insulation 17 surrounds the thermal store 16 and at least one secondary heat exchanger 30 with inlet 32 and outlet 33 is located externally of the thermal insulation 17. A substrate 19 surrounds the thermal insulation 17 and is in thermal contact with the secondary heat exchanger 30. The heat exchangers 25, 30 may comprise coiled or serpentine pipes. A controller may control the flow of a heated medium in a combined solar photovoltaic thermal collector (20, Fig. 1) to charge the main heat exchanger 25 and deliver heat to the secondary heat exchanger 30. An energy supply comprising the thermal store 16 and a method of improving the efficiency of a thermal store are also claimed.

Description

(54) Title of the Invention: Thermal store arrangement

Abstract Title: Thermal store with main and secondary heat exchangers (57) Athermal store arrangement (15, Fig. 1) has a thermal store 16 having a volume suitable for receiving a thermal store medium. The thermal store 16 incorporates a main heat exchanger 25 with an inlet 27 and an outlet 28. Thermal insulation 17 surrounds the thermal store 16 and at least one secondary heat exchanger 30 with inlet 32 and outlet 33 is located externally of the thermal insulation 17. A substrate 19 surrounds the thermal insulation 17 and is in thermal contact with the secondary heat exchanger 30. The heat exchangers 25, 30 may comprise coiled or serpentine pipes. A controller may control the flow of a heated medium in a combined solar photovoltaic thermal collector (20, Fig. 1) to charge the main heat exchanger 25 and deliver heat to the secondary heat exchanger 30. An energy supply comprising the thermal store 16 and a method of improving the efficiency of a thermal store are also claimed.

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THERMAL STORE CHARGING THERMAL SUPPLY

Thermal Store Arrangement

The present invention relates to a thermal store arrangement and a method of improving efficiency in a thermal store arrangement.

Since the oil crises of the 1970s, and with increasing awareness of climate change, energy-efficient building techniques have become viewed as a central pillar of the built environment of the future. In 2006, the UK Government launched the Code for Sustainable Homes, which aimed to tighten building regulations such that all new homes would be “Zero Carbon” by 2016, meaning that the building occupants would cause no net CO2 emissions into the atmosphere from occupying and using the buildings in the normal way. Under pressure from the housebuilding industry, the Code has since been abandoned, however interest and development of very energy-efficient buildings remains, with the EU poised to mandate new buildings to be “Nearly Zero Energy” by 2020 (2018 for public buildings) under the Energy Performance of Buildings Directive.

Many techniques have been developed for buildings to achieve these high standards, which essentially involve reducing energy demand to the minimum through energy-efficient building techniques and the use of energy-efficient lighting and appliances within the building, and then providing as much of the remaining energy demand as possible through the use of on-site renewable energy, such as solar thermal collectors or solar photovoltaic arrays.

While most of the developments have achieved excellent results from the point of view of a building’s electrical energy demand, the thermal energy demand remains a challenge. Although it is possible to reduce a building’s thermal energy demand significantly through what has become known as “Passivehouse” techniques (very high levels of thermal insulation and air tightness and the incorporation of heat-recovery ventilation systems, and the use of passive solar gain), in practice these techniques are difficult and expensive to implement consistently and do not eliminate the thermal energy demand to a level where solar gain and the heat given off by appliances and occupants is enough to keep internal temperatures at a comfortable level similar to what many people are able to enjoy with conventional central heating. Therefore some form of heat delivery system is usually required, which reduces the overall performance and increases energy use and CO2 emissions.

One particular area of development, mainly (but not exclusively) for temperate climates, is to incorporate a combined solar photovoltaic and solar thermal collector (“PVT” collector - photovoltaic/thermal) and a seasonal thermal store to provide electrical and thermal energy all year round from solar energy. This has the potential to make buildings truly zero carbon/zero energy by collecting solar thermal energy in the summer months when solar thermal energy is plentiful (and thermal demand is low) for use in winter when solar thermal energy is low (and thermal demand is high), while at the same time providing electrical energy for the building when available and for sale to the electricity supply grid when supply of electrical energy from the PVT collector exceeds demand. Such an arrangement would usually necessitate the use of a heat pump to perform two tasks; to lift the temperature of the energy coming from the collector when the thermal store temperature is relatively high, and to deliver heat to a building at a comfortable temperature when the temperature of the thermal store is below the delivery temperature.

A particular challenge with this approach is that when the various elements are sized optimally for a building at most latitudes, there is an excess of thermal energy available at the end of the summer and early autumn. This excess of thermal energy needs to be removed from the PVT collector in order to avoid the electrical conversion efficiency of the PVT collector being reduced. It is a feature of the majority of known photovoltaic solar cells used to convert solar irradiation into electricity, whether in PVT collectors or not, that the electrical conversion occurs most efficiently at low temperatures. For each degree centigrade rise in cell temperature the electrical efficiency can drop by as much as 0.55% when crystalline silicon cells are used, as is most common, with typical efficiency drops in the region 0.4% to 0.45% per 1°C rise. Since the thermal store has reached the target temperature at this time (end of summer/early autumn), no more thermal energy can be stored there. A possible solution is to incorporate external radiators on a shaded part of the building to dissipate the surplus heat; however this not only has aesthetic implications but also wastes this excess thermal energy. It is to this problem that the present invention is addressed; it provides a way to remove the excess thermal energy from the PVT collector without the need for unsightly external radiators and use it in such a way as to provide a benefit instead of a waste.

According to a first aspect of the present invention there is provided a thermal store arrangement comprising:

a thermal store having a volume for receiving, in use, a thermal store medium and having a main heat exchange means disposed within said volume, the main heat exchange means having main inlet and outlet means, a thermal insulation component which at least partially surrounds the thermal store, one or more secondary heat exchange means provided externally of the thermal insulation component, the or each secondary heat exchange means having secondary inlet and outlet means, a first substrate at least partially surrounding the thermal insulation component and in thermal contact with the secondary heat exchange means.

When such a thermal store arrangement is used with a PVT collector, once the thermal store target temperature is reached (representing enough stored thermal energy to supply the late-autumn/winter/early-spring heating loads), then, during periods of surplus thermal energy availability the thermal transfer fluid can be diverted wholly or partially from the main heat exchanger to the secondary heat exchanger assembly thereby releasing the heat into the first substrate. This effectively cools the PVT collector, thereby improving the electrical efficiency thereof. This use of the secondary heat exchanger slowly raises the temperature of the first substrate of the thermal store arrangement, thereby reducing the temperature difference across the thermal insulation component. This reduction in temperature difference results in a reduction of thermal losses from the thermal store. Because all substrate types have a degree of thermal conductivity, some of the heat will be transferred away from the thermal store area overnight thereby allowing more heat to be absorbed the next day. This ultimately results in an overall improvement in electrical and thermal efficiency. It also means that the thermal store can be smaller than it would otherwise need to be, by reducing losses and by allowing a larger PVT collector array than would otherwise be permitted without overheating problems. The PVT collector is therefore more able to supply useful heat directly to the building in the shoulder months (spring and autumn), reducing the need for storage capacity.

In some preferred arrangements the or each secondary heat exchange means is disposed between the first substrate and the thermal insulation component. In other arrangements the or each secondary heat exchange means is disposed externally of the first substrate, between and in thermal contact with a surrounding substrate, the thermal store arrangement in use being disposed on or buried in or partially burred in the surrounding substrate.

With some embodiments the first substrate is a retaining structural shell which, in use, is disposed on or buried in or partially buried in a surrounding substrate and preferably the retaining structural shell fully surrounds and encloses the thermal insulation component except for the main inlet and outlet means. In some cases the first substrate is a retaining structural substrate such as a concrete wall. Ideally the first substrate is in contact with the outer surface of the thermal insulation component.

Often the main heat exchange means comprises one or more main coiled or serpentine pipes and/or the or each of the secondary heat exchange means comprises a secondary coiled or serpentine pipe. In some arrangements the or each secondary pipe has a flow portion which extends from its associated secondary inlet means and which is disposed adjacent the thermal store, and a return portion leading to its associated secondary outlet means and disposed further from the thermal store than said flow portion.

Conveniently, the thermal store is generally cuboid in shape and one or more of the faces of the thermal store is provided with the secondary heat exchange means. With some embodiments the secondary heat exchange means are provided at upper regions of the thermal store. Usually, the thermal insulation component fully surrounds and encloses the thermal store except for the main inlet and outlet means and also the thermal store is provided with a waterproof internal liner.

Preferably control means is provided for controlling the proportion of flow to the main heat exchange means and to said one or more secondary heat exchange means, ft is preferred that the control means, in use, controls the flow of a heated medium in a combined solar photovoltaic and solar thermal collector (PVT collector) to charge the thermal store via the main heat exchange means and/or to deliver heat to the or each secondary heat exchange means and the control means includes a number of sensors.

The invention also provides an energy supply system comprising a thermal store arrangement as disclosed above, in conjunction with a combined solar photovoltaic and solar thermal collector (PVT collector).

According to a second aspect of the present invention there is provided a method of improving efficiency in a thermal store arrangement comprising: a thermal store having a volume in which a thermal store medium is disposed and in which is disposed a main heat exchange means having main inlet and outlet means; a thermal insulation component which at least partially surrounds the thermal store, said method comprising the steps of providing one or more secondary heat exchange means externally of the thermal insulation component and providing a first substrate at least partially surrounding the thermal insulation component and in thermal contact with the secondary heat exchange means.

Embodiments of the present invention will now be described in more detail. The description makes reference to the accompanying diagrammatic drawings in which:

Figure 1 is an illustrative diagram of a PVT collector system arranged on a building,

Figure 2 is a vertical section through an example of a thermal store according to the present invention,

Figure 3 is a side view of the thermal store shown in figure 2,

Figure 4 is a side view similar to figure 3 of an alternative thermal store according to the present invention,

Figure 5 is a vertical section similar to figure 2 through another example of a thermal store according to the present invention,

Figure 6 is a vertical section similar to figure 2 through a further example of a thermal store according to the present invention,

Figure 7 is a vertical section similar to figure 6 through another example of a thermal store according to the present invention,

Figure 8 is a vertical section similar to figure 2 through a still further example of a thermal store according to the present invention, and

Figures 9a and 9b are flowcharts illustrating the basic modes of operation of a thermal store according to the present invention.

Figure 1 represents a building 10 having a roof 11 and walls 12 built on a surrounding substrate 13 or ground. Below ground level 14 there is provided a thermal store arrangement 15 comprising a thermal store 16 defining an internal volume filled with a thermal store medium such as a high thermal-mass material, typically water although other materials are possible. Another such high thermalmass material could be, either partially or entirely, a phase-change material with a high latent heat capacity. Surrounding the thermal store 16 is a layer of thermal insulation 17, typically with an inner protective membrane 18 between the thermal store medium and the insulation layer 17. Usually the protective membrane 18 will be waterproof. Surrounding the insulation layer 17 is a substrate in the form of a structural shell 19, typically of concrete or other structural load-bearing material.

In such arrangements, the thermal store arrangement 15 is usually, but not necessarily, buried underground and situated adjacent the building 10 or, as shown, is incorporated underneath the building, typically but not exclusively forming part of the building foundations.

On the roof 11 is provided a PVT collector 20 in the form of an array of combined solar photovoltaic and solar thermal collectors. The PVT collector 20 provides thermal energy 21 and electrical energy 22 to the building. The electrical energy 22 can be connected via an inverter to meet the electrical loads of the building, and/or charge batteries. Any excess electrical energy can be sold back to the local electricity grid. The thermal energy 21 can be used to meet the thermal loads of the building, such as hot water/heating, and excess thermal energy can be directed via a heat pump to the thermal store 15. Typically, a heat exchanger (not shown) is incorporated in the thermal store for this purpose. The heat exchanger is often but not exclusively formed of copper pipes, and delivers and extracts heat to the thermal store medium as required by way of a thermal transfer fluid, such as a water/glycol antifreeze mix, which circulates within the heat exchanger pipes.

As mentioned in the introduction, such known thermal store arrangements in association with PVT collectors are advantageous but efficiency can be improved.

Figures 2 to 8 illustrate improved thermal store arrangements according to the present invention. Like reference numerals for like parts have been used.

In figures 2 and 3 (and in subsequent figures), the thermal store arrangement 15 is shown without its associated building. A main heat exchanger 25 in the form of a coiled or serpentine pipe 26 made of copper or other suitably conductive material is shown in the volume defined by the thermal store 16, the pipe 26 having an inlet 27 and an outlet 28. The inlet 27 and outlet 28 are shown with optional thermal insulation sleeving where the flow and return are provided close to each other at the entrance to the thermal store 16 so that heat from the inlet flow is not absorbed by the outgoing return flow or the surrounding air. The external surface of the thermal store arrangement 15 can also be covered with a waterproof bitumen layer (‘tanked’) or the structural shell 19 could be made of waterproof material/concrete to ensure that the insulation layer 17 remains dry, this being important for the effectiveness of the insulation.

It is preferred that the thermal insulation layer 17 completely surrounds and encloses the volume of the thermal store 16 and that the structural shell 19 or first substrate completely surrounds and encloses the thermal insulation layer 17, in contact therewith but, of course, with the inlet 27 and outlet 28 extending through the insulation layer 17 and the structural shell 19.

Surrounding the shell 19 of the thermal store arrangement, partially or completely as required, is a secondary heat exchange assembly 30 comprising secondary coiled or serpentine pipes 31 on the external, cold side of the insulation layer 17, buried in the surrounding substrate 13 around the thermal store arrangement 15. The surround substrate 13 can be soil, clay, sand, shale, rock, or similar or any mix thereof as may be found at the sub-surface at the site. The secondary pipes 29 are typically made of a tough, high-density flexible plastic although other materials may be used. The secondary pipes 29 have secondary inlets 32 and outlets 33, together with thermal insulation sleeving 34 as appropriate. Once the thermal store target temperature is reached (representing enough stored thermal energy to supply the late-autumn/winter/early-spring heating loads), then, during periods of surplus thermal energy availability the thermal transfer fluid is diverted wholly or partially from the main heat exchanger 25 to the secondary heat exchanger assembly 30 thereby releasing the heat into the surrounding substrate 13. This effectively cools the PVT array 20, thereby improving the electrical efficiency of the PVT array 20. This use of the secondary heat exchanger 30 slowly raises the temperature of the surrounding substrate 13 and the first substrate/structural shell 19 of the thermal store arrangement 15, thereby reducing the temperature difference across the thermal insulation layer 17. This reduction in temperature difference results in a reduction of thermal losses from the thermal store 16. Because all substrate types have a degree of thermal conductivity, some of the heat will be transferred away from the thermal store area overnight thereby allowing more heat to be absorbed the next day. This ultimately results in an overall improvement in electrical and thermal efficiency. It also means that the thermal store 16 can be smaller than it would otherwise need to be, by reducing losses and by allowing a larger PVT collector array 20 than would otherwise be permitted without overheating problems, which PVT collector 20 is therefore more able to supply useful heat directly to the building 10 in the shoulder months (spring and autumn), reducing the need for storage capacity.

In order to ensure as much of the excess heat as possible is delivered as close as possible to the thermal store 15, the secondary heat exchanger assembly 30 would typically feature thermal insulation sleeving 34 around the secondary pipes 31 where the secondary inlet and outlet are provided close to each other 6. This prevents heat from the inlet flow being absorbed by the return before getting to the substrate. It is also a typical feature that a section 35 of the return is routed away from the thermal store 15 so that in the case that a lot of heat has been absorbed by the substrate surrounding the thermal store, the thermal transfer fluid can still release some of the thermal energy into the surrounding substrate 13 away from the thermal store, thereby ensuring cooling is still possible. This return section 35 may be extended and looped within the surrounding substrate 13 away from the thermal store 15 depending on anticipated surplus thermal energy and the thermal properties of the surrounding substrate 13.

Figure 3 shows an external view of the thermal store arrangement 15 in which one secondary heat exchanger 30a is provided at one external side of the thermal store 16 and another secondary heat exchanger 30b forms two side assemblies and an under-assembly. Other arrangements of secondary heat exchangers are, of course, possible depending on the particular requirements and the location of the thermal store arrangement 15.

An alternative shown in Figure 4 has the secondary heat exchanger assemblies 30 surrounding only the upper section of the thermal store 15. This can often be cost-effective especially if the thermal store 15 is deep because some thermal stratification will occur such that only the upper part of the thermal store 15 will be at high temperatures where the losses are greatest and where the absoiption of heat at the cold-side of the thermal insulation layer 17 will give the most benefit.

Another alternative arrangement is shown in Figure 5 and provides the secondary heat exchanger assembly 30 contained within the first substrate/structural shell 19. Preferably in this embodiment the secondary heat exchanger 30 would be positioned close to the thermal insulation layer 17 as shown in order to provide more responsive loss-reduction from the thermal store 16 because the heat is delivered more quickly to the cold side of the thermal insulation layer 17. Depending on the anticipated volume of excess heat, this arrangement may potentially give a better overall performance but at a cost penalty because its construction may be more expensive, particularly on a retro-fit on an existing thermal store installation.

Figures 6 and 7 show still further alternatives where the thermal store assembly 15 is not buried or even partially buried but is instead constructed on the ground surface 14. Figure 5 shows a secondary heat exchanger assembly 30 on the underside only of the first substrate/shell 19. If the thermal absorption capacity underneath the thermal store 15 is not sufficient for the anticipated excess thermal energy, then the secondary heat exchanger assembly 30 could extend beyond the footprint of the base of the thermal store 16 so as to dissipate more heat into the surrounding substrate 13. In addition, in order to improve the reduction of thermal losses benefit, if space permits, the thermal store 16 could be made shallower and wider, thereby having a larger footprint for the same internal volume and therefore a higher surface area in contact with the surrounding ground substrate 13. Figure 6 shows a secondary heat exchanger assembly 30 contained within the first substrate of the external retaining structure/shell 19 and is therefore also dissipating heat to the air at the sides. This improves heat dissipation but the gains from reducing the temperature difference across the thermal insulation layer 17 on the air-exposed sides are reduced because the elevated temperatures of the external retaining structure/shell 19 do not persist for as long beyond the heating time.

Figure 8 shows an alternative example whereby the thermal store assembly 16 is created from a void within a first substrate which is a structural substrate 19, typically concrete, for example within a large commercial building where the thermal store 15 is neither buried within nor in contact with the ground/surrounding substrate 13. In such arrangements, the structural substrate can be viewed in some respects as a combined first substrate/shell and surrounding substrate of earlier described embodiments. In such circumstances the same principle can be applied using a secondary heat exchanger assembly 30 contained within the surrounding structural substrate 19, similar in a number of respects to Figures 5 & 7. In this particular example the secondary heat exchanger assembly surrounds the insulation layer 17 of the thermal store 16 on all sides, although this may not be necessary in every case depending on the absorption requirements for the volume of excess thermal energy anticipated.

Figures 9a and 9b are simple flowchart diagrams showing the heat-flow arrangement for two basic modes of operation:

Mode 1: Charging the thermal store 16 with heat from the PVT array 20

Mode 2: Delivering heat to the building 10 from either the PVT array 20 or the thermal store 16.

The arrows on the lines between the boxes represent various valves that can be opened or closed in order to control the flow of heat under various conditions.

Mode 1: During charging of the thermal store 16, the heat at first flows directly from the PVT array 20 but once a set temperature is reached in the thermal store 16 (by means of suitable sensors for example) this is no longer efficient and the heat is diverted via the heat-pump so the delivery temperature to the thermal store can be raised and the PVT array cooled at the cost of some electrical energy consumption. Once the target temperature is reached it is maintained by occasionally topping up any losses and diverting any surplus heat to the first/surrounding substrate/air so as to boost the PVT collector 20 electrical conversion efficiency while at the same time reducing losses of the thermal store 16.

Mode 2: During the supply of heat, the source can be either the PVT array 20 or the thermal store 16 and the heat can either flow directly to the building loads or via the heat-pump, as determined to be the most efficient depending on thermal store temperature, atmospheric conditions and demand for the time of year. When the thermal store 16 temperature drops below the delivery temperature the heat-pump is used to continue extracting heat from the thermal store 16.

It is noted that the secondary heat exchanger assembly 30 is disposed on the external, cold-side of the thermal insulation layer 17, thereby dissipating excess heat into the surrounding substrate 13 and/or first substrate/shell 19. This provides the following benefits:

1. Allowing a larger PVT collector 20 than would otherwise be possible without overheating problems which PVT collector 20 is therefore more able to supply useful heat directly to the building 10 in the shoulder months (spring and autumn), reducing the need for storage capacity and allowing the thermal store 16 to be smaller and therefore cheaper.

2. Achieving the above without wasting the excess heat. The excess heat is used to reduce the temperature difference across the thermal insulation layer 17 so that thermal losses are reduced. This ultimately provides an improvement in overall efficiency and also allows the thermal store 16 to be smaller and cheaper.

In the embodiments described above, the thermal store arrangement 15 is shown as being cuboid having a top, bottom and four sides but it will be appreciated that other shapes are of course possible depending on design/location requirements. Additionally, it is beneficial that the pipes of the secondary heat exchanger(s) are in thermal contact with the first substrate/shell and/or the surrounding substrate in order to improve efficiency.

Claims

1. A thermal store arrangement comprising:

2. A thermal store arrangement as claimed in claim 1 wherein the or each secondary heat exchange means is disposed between the first substrate and the thermal insulation component.

3. A thermal store arrangement as claimed in claim 1 wherein the or each secondary heat exchange means is disposed externally of the first substrate, between and in thermal contact with a surrounding substrate, the thermal store arrangement in use being disposed on or buried in or partially buried in the surrounding substrate.

4. A thermal store arrangement as claimed in claim 1 or claim 2 wherein the first substrate is a retaining structural shell which, in use, is disposed on or buried in or partially buried in a surrounding substrate.

5. A thermal store arrangement as claimed in claim 4 wherein the retaining structural shell fully surrounds and encloses the thermal insulation component except for the main inlet and outlet means.

6. A thermal store arrangement as claimed in claim 2 wherein the first substrate is a retaining structural substrate.

7. A thermal store arrangement as claimed in any one of claims 1 to 6 wherein the first substrate is in contact with the outer surface of the thermal insulation component.

8. A thermal store arrangement as claimed in any one of claims 1 to 7 wherein the main heat exchange means comprises one or more main coiled or serpentine pipes and/or the or each of the secondary heat exchange means comprises a secondary coiled or serpentine pipe.

9. A thermal store arrangement as claimed in claim 8 wherein the or each secondary pipe has a flow portion which extends from its associated secondary inlet means and which is disposed adjacent the thermal store, and a return portion leading to its associated secondary outlet means and disposed further from the thermal store than said flow portion.

10. A thermal store arrangement as claimed in any one of claims 1 to 9 wherein the thermal store is generally cuboid in shape, having top, bottom and four side faces.

11. A thermal store arrangement as claimed in claim 10 wherein one or more of the faces of the thermal store is provided with the secondary heat exchange means.

12. A thermal store arrangement as claimed in any one of claims 1 to 11 wherein the secondary heat exchange means are provided at upper regions of the thermal store.

13. A thermal store arrangement as claimed in any one of claims 1 to 12 wherein the thermal insulation component fully surrounds and encloses the thermal store except for the main inlet and outlet means.

14. A thermal store arrangement as claimed in any one of claims 1 to 13 wherein the thermal store is provided with a waterproof internal liner.

15. A thermal store arrangement as claimed in any one of claims 1 to 14 wherein control means is provided for controlling the proportion of flow to the main heat exchange means and to said one or more secondary heat exchange means.

16. A thermal store arrangement as claimed in claim 15 wherein the control means, in use, controls the flow of a heated medium in a combined solar photovoltaic and solar thermal collector (PVT collector) to charge the thermal store via the main heat exchange means and/or to deliver heat to the or each secondary heat exchange means.

17. A thermal store arrangement as claimed in claim 16 wherein the control means includes a number of sensors.

18. An energy supply system comprising a thermal store arrangement as claimed in any one of claims 1 to 17 in conjunction with a combined solar photovoltaic and solar thermal collector (PVT collector).

19. A method of improving efficiency in a thermal store arrangement comprising: a thermal store having a volume in which a thermal store medium is disposed and in which is disposed a main heat exchange means having main inlet and outlet means; a thermal insulation component which at least partially surrounds the thermal store, said method comprising the steps of providing one or more secondary heat exchange means externally of the thermal insulation component and providing a first substrate at least partially surrounding the thermal insulation component and in thermal contact with the secondary heat exchange means.

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Application No: GB 1612413.3 Examiner: Dr Rhys Williams