GB2564010A

GB2564010A - Water heating apparatus

Info

Publication number: GB2564010A
Application number: GB1810068.5A
Authority: GB
Inventors: Smit Alistair; Basile Martino
Original assignee: Magic Thermodynamic Box Ltd
Current assignee: Magic Thermodynamic Box Ltd
Priority date: 2017-06-19
Filing date: 2018-06-19
Publication date: 2019-01-02
Also published as: WO2018234786A1; GB201709759D0; GB201810068D0

Abstract

A water heating apparatus having a water cylinder 10, a first heat exchanger in the form of a pipe 13 coiled around the outer surface 12 of the cylinder such that the winds of the pipe are spaced apart by a gap 15 so they dont engage with one another, a compressor (26, fig 4) connected to the first heat exchanger to supply compressed hot refrigerant, and an expansion valve that expands liquid refrigerant from the first coiled pipe as it flows to a second heat exchanger (27, fig 7) in the form of a thermodynamic panel (28, fig 6a, 6b) formed by roll bonding that is in thermal communication with an environmental heat source. The water cylinder and first heat exchanger may be contained within a casing 21 with a square cross-section, and the thermodynamic panel, may be mounted on the casing. The second heat exchanger may feature a second thermodynamic panel or a single double panel (fig 9) that is comprised of a pair of overlaid single evaporator heat exchangers.

Description

WATER HEATING APPARATUS

This invention relates to apparatus for efficient heating and storing of water within the cylinder of a hot water system. Furthermore, this invention relates to the heating of water within the cylinder of a hot water system in an environmental friendly and economical manner.

There are conventionally two types of domestic hot water systems; open vented and unvented. Both system types include a water cylinder. The cylinder typically incorporates an internal coil which is operatively connected to an external boiler and arranged indirectly to heat water within the cylinder. In unvented systems, water is supplied to the cylinder directly from the mains whereas in a vented system, water is supplied to the cylinder from an external water tank, where the water is also stored.

The efficiency of the cylinder is measured by heat loss. The length of time taken for water within the cylinder to cool down is affected by the extent of insulation of the cylinder. The manufacture of such cylinders must meet the minimum requirements stipulated by EU regulations, including the requirement clearly to identify the heat loss value and energy rating, in order to display the efficiency of the cylinder.

The use of such cylinders generally requires the provision of a boiler, typically an electric, gas or oil power source and the water inlet either connected to the mains water supply or to a water storage tank, as described above. As such, existing systems are not environmentally friendly or economical. Furthermore, such systems do not serve as viable solutions for generating hot water in areas where there are no or limited utility services.

It is an aim of the present invention to provide integrated apparatus which heats and also stores water within a water cylinder and which serves to improve the thermal efficiency of existing arrangements. It is a further preferred aim of the present invention to provide apparatus which is portable and which may be deployed as a unit.

According to this invention, there is provided heating apparatus comprising: a potable water cylinder; a first heat exchanger comprising a tubular coil wound around and in thermal contact with the outer periphery of the cylinder such that adjacent winds are in a spaced arrangement such that they do not engage each other; a compressor operatively connected to the first heat exchanger for the supply of compressed hot refrigerant thereto to enable heat to be transferred from the refrigerant to water within the water cylinder; an expansion valve that receives cooled liquid refrigerant from the first heat exchanger; and a second heat exchanger, comprising a roll bond aluminium thermodynamic panel, that receives cool refrigerant from the expansion valve and is in thermal communication with an environmental heat source.

The compressor and expansion valve may be part of a heat pump which causes heat energy to be passed through the heat exchanger. The expansion valve is operatively connected to the heat exchanger and arranged to receive cooled liquid refrigerant therefrom. Preferably the cylinder is made of metal, and more preferably from stainless steel.

The heat pump is part of a heat exchange system which supplies hot refrigerant to and receives cooled refrigerant from the heat exchanger. When the hot refrigerant comes into contact with the cooler cylinder the heat energy transfers to the cylinder and the now cooler refrigerant returns back to the heat exchange system so it can then pick up more heat and repeat the cycle.

In a preferred arrangement, the heat exchange system is a condenser heat exchange system. The compressor compresses heated refrigerant in vapour form and this causes the temperature of the vapour to rise, resulting in an even hotter refrigerant. The expansion valve, also known as a throttling device, allows the pressure of the refrigerant to reduce rapidly and this results in the adiabatic flash evaporation of part of the liquid refrigerant. This, so-called, autorefrigeration effect which results from the adiabatic flash evaporation lowers the temperature of the liquid and vapour refrigerant mixture.

The applicant discovered that when adjacent winds of the coil touch each other, some of the heat energy travelling through the coil is transferred back or forward into the adjacent winds. In effect, in the process of transferring heat to the cylinder the refrigerant also partly heats itself. By spacing adjacent winds of the coil it has been found that the efficiency of heat transfer can be significantly improved and more heat is transferred to the cylinder.

Preferably the tubular coil is formed from pipes that are substantially D-shaped in cross section. This may serve to increase the efficiency of heat transfer as it means more contact can be made between the coil and the water cylinder without significantly increasing the non-contacting surface area. The pipe forming the tubular coil may instead have a substantially rounded rectangular profile in cross section. This design also provides a double skinned barrier between the water in the cylinder and the refrigerant.

The cylinder plus connected first (condenser) heat exchanger are not enclosed within a single unit with the second (evaporator) heat exchanger, they are ideally in a split unit system. The cylinder plus connected first (condenser) heat exchanger are within a single internal unit, and the second heat exchanger is a separate external unit, the two units connected by adjoining pipework during installation.

The roll bond aluminium thermodynamic panel ideally utilises passive convection, as opposed to forced convection, as to not necessitate a fan within the system. The aluminium thermodynamic panel evaporator heat exchanger is not enclosed, to maximise thermal communication within an environmental heat source. Furthermore, by fact that that the evaporator thermodynamic panel may be exposed, it can be situated externally either on a wall or roof. Further it may be black in colour, so that the aluminium thermodynamic panel benefits from additional energy absorption in the form of solar irradiance. With this consideration the system can be considered a hybrid between a typical heat pump cycle, in thermal communication from an environmental heat source, and a solar thermal cycle.

The heating apparatus, when comprising two separate but linked parts (the internal single unit and the external thermodynamic panel) uniquely utilises the aluminium roll bond thermodynamic panel as an evaporator benefitting from multiple energy sources. This can be compared to prior art use of a finned tubular heat exchanger, with an accompanying fan that uses only thermal energy from an environmental air heat source.

The cylinder is preferably housed in a casing. In this way, tapings for plumbing connections may be arranged to extend from a single area of the casing to provide an organised access point for those connections. The casing may be generally square in cross section. This may serve to assist in ensuring thermal efficiency since a square configuration allows more insulation to be used between the casing and the cylinder, particularly in the corners. Additionally, a square profile casing for the cylinder also permits better use of space; a cupboard into which the cylinder may be located in a house is often square and therefore a square profile better fills that space.

The water cylinder may be suitable for use as part of a hot water system and may comprise an inlet taping and an outlet taping for the flow of water therethrough. The location of the water outlet taping enables the cylinder to be plumbed in either of a vented or unvented configuration, depending on where the apparatus is to be used. The apparatus in use may have two flow paths in thermal communication with each other, a first flow path for refrigerant and a second flow path for water from the water cylinder. Water may be pumped from the water cylinder through the second flow path and back to the cylinder by a circulating pump.

There are various types of heating systems on the market which absorb heat from various sources such as water, ground, stream, outer air, exhaust air and others. In general, such systems are classified based on where they source their heat. For example, ground source heat pumps obtain heat from the ground and air source heat pumps obtain heat from the air.

Air to water heat pumps currently available in the market make use of a single unit which is typically located outdoors. In these devices, the heat pump has an evaporator and a fan is provided to force the air through the evaporator to absorb the heat. A condenser transfers heat to the heating medium which in most cases is a water/glycol mix.

In the present invention, heating is preferably effected by utilising ambient temperature from the atmosphere. In this arrangement, the heat pump may be configured for connection to a heat energy providing panel for the supply of hot refrigerant to the heat pump and the transfer of cooled refrigerant back to the panel. The heat energy providing panel is a thermodynamic panel.

The second heat exchanger preferably includes a second thermodynamic panel in thermal communication with an environmental heat source (usually ambient heat) to heat cooled refrigerant passing therethrough.

It may be beneficial in some situations to amplify the uplift and recovery time of the thermodynamic panel and in this case the condenser second heat exchanger system may comprise a thermodynamic double panel, having a pair of single thermodynamic panels. The panels of a double panel thermodynamic arrangement may be provided in a superimposed configuration and appropriately interconnected by pipes.

The apparatus may be configured for generally permanent installation within a domestic or commercial setting. In this case, the thermodynamic panel may be spaced from the cylinder and located at a remote site; for example, the cylinder may be installed in a house and the thermodynamic panel attached to the outside wall of the house or may be located in another area of the house (such as a larder) in order to maximise the ambient air conditions. As such, in this case it is probable that the pipework between the cylinder and the thermodynamic panel will need to be connected in situ.

All the system components, with the exception of the evaporator second heat exchanger, may be mounted inside a single unit. The cylinder unit without the evaporator second heat exchanger introduces versatility in location of the single unit, facilitating the site location of the combined unit within a domestic envelope without compromising the renewability of heat generation, i.e. the second heat exchanger can be installed external to the envelope, and draw energy from an environmental heat source.

In some cases, however, it may be necessary to generate hot water in places where no services or limited services are available. Such cases include, but are not limited to, military or refugee camps, for example. In this arrangement, it is beneficial if the apparatus can be installed in a simply way without the additional need to connect refrigeration pipework between the thermodynamic panel and the cylinder at the point of installation. As such, for versatility in a second embodiment of the invention, the thermodynamic panel may be connected directly to the cylinder or more preferably the cylinder casing. In this way, the apparatus can be configured so that it is supplied with the refrigerant pipework already connected. Preferably, in this arrangement, the thermodynamic panel is configured to extend at least partly around the external casing of the cylinder. Where the casing is generally square in cross section, the thermodynamic panel may be arranged in a U-shaped configuration, so as to extend over three of the four side walls of the casing. In this way, the fourth side may be left free for access to plumbing and/or electrical connections extending from the fourth side of the casing.

Preferably the apparatus is portable, particularly where the thermodynamic panel is operatively connected to the cylinder prior to installation. The apparatus may be a portable self-contained unit that may be taken to any place where hot water is needed and simply plugged into a water source to deliver hot water, as required. To be portable, the apparatus may be mounted on a handling structure. That handling structure may include wheels and may also have a handle to assist with mobility.

The system may allow the radiant heat energy from the sun, and/or the radiated, convected, and/or conducted heat from the surrounding environment, to be transferred from the thermodynamic panel, into the water of the cylinder thereby providing considerable flexibility for the provision of hot water to domestic, commercial, and industrial, systems.

By utilising radiant heat energy the present invention does not require the use of a separate boiler or electricity or gas services. As a backup arrangement, the cylinder may further comprise an internal heat exchange coil for connection to a traditional boiler, if necessary. Water can be heated at all times, including at night and, since ambient air is being utilised, the thermodynamic panel need not be positioned outside. As such, in permanent installations the requirement for scaffolding to attach the panel externally to a building wall is obviated.

To further enhance thermal efficiency, thermal insulation may be included around the cylinder. The thermal insulation may be a provided in the form of a thermal jacket or sleeve wrapped around at least the cylinder of the apparatus. Preferably the thermal insulation comprises a thermal foil. The insulation is preferably wrapped around the cylinder and the attached tubular coils of the apparatus. Alternatively, or beneficially in addition thereto, insulation foam may be applied between the cylinder and the cylinder casing.

In a preferred arrangement, to maximise thermal efficiency, the thermal insulation may also include a conductivity paste applied to the external wall ofthe cylinder. The conductivity paste may be applied to the whole outer periphery of the cylinder or only part of it. Preferably, the conductivity paste is applied to the cylinder on the regions of contact between the cylinder and the tubular coil.

The apparatus and, in particular, the cylinder may be available in different sizes depending on the water requirements.

The apparatus is preferably arranged to replace a cylinder of a hot water system, or other such system where hot water is required. Conventionally hot water rises but the configuration and thermal efficiency of the apparatus of the present invention ensures that there is stratification from top to bottom of the cylinder, such that the temperature of water within the cylinder is constant throughout.

By way of example only, an embodiment of this invention will now be described in detail, reference being made to the accompanying drawings in which:

Figure 1 is a perspective view of the cylinder of the apparatus of the present invention;

Figure 2 is a sectional view of part of the cylinder of Figure 1;

Figure 3 is a cross-sectional view through one of the tubular coils of Figures 1 and 2;

Figure 4 is a front view of a first embodiment of apparatus of the present invention configured for connection to a thermodynamic panel;

Figure 5 is a cross-sectional plan view through the cylinder of Figure 1 through line A-A;

Figure 6a is a front view of one variant of a second embodiment of apparatus of the present invention incorporating a mounted thermodynamic panel;

Figure 6b is a front view of another variant of the second embodiment of apparatus;

Figure 7 is a two-dimensional schematic view of the apparatus of the present invention.

Figure 8 shows front, rear and side views of a single thermodynamic panel; and

Figure 9 shows front, rear and side views of a double thermodynamic panel.

Referring initially to Figure 1 there is shown a vessel in the form of a metal cylinder 10 for containing potable water to be heated and stored. The cylinder 10 includes a generally dome-shaped top and bottom 11 and a continuous side surface 12. A heat exchanger in the form of a tubular coil 13 is connected to and arranged around the outer surface 12 of the side of the cylinder.

The cylinder 10 includes several aligned tapings 14 along the length of the cylinder 10 for plumping connections in order to connect the cylinder 10 to various inputs and outputs, including connections to facilitate the supply of water to and from the cylinder. The arrangement of the tapings 14 in this way not only provides an organised access point for those connections but also enables the cylinder 10 to be plumbed in either vented or unvented which provides great versatility.

As best seen in Figure 2, the coil 13 is wound around the cylinder 10 with spacing 15 between adjacent winds such that they do not touch each other but do contact the cylinder 10. This ensures that as much heat as possible, from hot refrigerant passing through the coil 13, is transferred to the cylinder 10 rather than to adjacent coils 13. Though not visible in the Figures a heat transfer paste is applied to the cylinder 10 and the coil pipe 13 in the regions of connection to enhance the thermal efficiency of heat transfer.

Referring now to Figure 3, the tubular coil pipe 13 is generally rectangular in cross section, having rounded edges 18. The rectangular coil pipe 13 has four sides, two long sides 19 and two shorter sides 20. The coil pipe 13 is connected to the cylinder 10 along one of the long sides 19 to allow maximum contact between the coil 13 and the cylinder 10. The rectangular coil pipe 13 is formed from copper to provide a good heat transfer ratio. The cylinder 10 and attached tubular coil 13 are surrounded by a thermal foil (not visible) to provide insulation and thus assist with effective heat transfer between the coil 13 and cylinder 10. The coil pipe can also be generally D-shaped with the flattened portion in contact with the surface of the cylinder 12.

Figures 4 and 5 show the cylinder 10 of Figure 1 housed in a casing 21. The casing 21 has a generally square outer profile (square or substantially square in horizontal cross section) and overall has a rectangular-box type shape. The square configuration of the casing 21 defines gaps 22 between the cylinder 10 and the casing 21, particularly in the corners of the casing 21. These gaps 22 are filled with insulative foam (not visible in Figures), such as polyurethane foam to provide enhanced thermal insulation and thus to maximise the thermal efficiency of the cylinder 10. The gaps 22 may also provide space for pipes. The gaps 22 in the corners may be as much as 200mm in size to allow a large quantity of foam to be inserted. However, the spacing between the cylinder 10 and the casing 21 can be designed to be smaller or larger depending on the requirements of the system. The cylinder 10 is thus insulated by thermal foil and thermal foam (neither shown in Figures) and includes thermal conductivity paste between the coil 13 and cylinder 10, all of which serve to ensure that the cylinder 10 has the maximum ‘A’ energy rating.

The uppermost part 25 of the casing 21 of the apparatus shown in Figures 4, 6a and 6b houses a heat pump 26 which is operatively connected to the tubular coil 13 as will be described in more detail with reference to Figure 7, which shows the heat pump 26 as part of a condenser heat exchange system 27, incorporating a thermodynamic panel 28.

Figure 4 illustrates a first embodiment which is designed to be installed at a fixed location with the heat pump 26 being configured for connection to a thermodynamic panel 28 during installation. In this embodiment, the location of the thermodynamic panel 28 can be selected to ensure maximum heat transfer- this may be installed outside or indoors depending on the conditions, suitability and user preference.

Figures 6a and 6b illustrate two variations of a second embodiment 23, 24 which is designed to be portable and to be deployed as a single unit. Both of these variants include all of the features of the first embodiment but are operatively and physically connected to the thermodynamic panel 28. In this case, the thermodynamic panel 28 is generally U-shaped and, as well as being operatively connected to the heat pump 26, is mounted to the outer periphery of the cylinder casing 21. The thermodynamic panel 28 extends fully around three sides of the cylinder casing 21 but only partly around the fourth side 29 (not visible in Figure 6b), leaving a region of the casing 21 exposed. This region conveniently provides access to the tapings 14 for plumbing connections.

The second embodiments 23, 24 of apparatus each include a frame 31, 32 on which the casing 21 and enclosed cylinder 10 is mounted. The frame 31, 32 includes a base 33 on which the cylinder casing 21 sits and which incorporates two opposed wheels 34 adjacent one edge of the base 33 and a central wheel 35 adjacent another edge. This embodiment is intended to be portable, and a fixed installation would not need wheels or a handle. Extending upwards from the base, the frame includes a bar 36, 37 by which the apparatus may be tilted, so as to rest solely on two wheels 34 and a handle 38 to facilitate wheeled movement of the apparatus when necessary. The wheels, frame and handle could be removably engageable with the rest of the portable version. This could allow it to be transported and then deposited at a use location before disengaging the wheels, frame and handle to use on other units. They could be reengaged when it was time to move the unit again.

The apparatus of Figure 6a differs from that of 6b only insofar as, in Figure 6a the frame 31 is designed to receive the cylinder casing 21 from the front so that the tapings 14 are facing the bar 36 of the frame 31. In Figure 6b, the frame 32 is designed to receive the cylinder casing 21 from the rear so that the taping connections 14 face away from the bar 37 of the frame 32. The frame 32 of Figure 6b has a bar 37 with a curved configuration to as to correspond to the shape of the thermodynamic panel 28 surrounding the cylinder casing 21. The bar 36 of Figure 6a is substantially linear.

Referring now to Figure 7, parts of the condenser heat exchange system 27 will now be described along with the operation of the apparatus in use. The heat exchange system comprises a heat pump 26 and a thermodynamic panel 28. In use, the heat pump 26 transfers a refrigerant around the system, along the path indicated by the arrows, in order to transfer heat from the condenser heat exchange system 27 to the water cylinder 10, and then back again to the system 27. The thermodynamic panel 28 includes a second heat exchanger 40 which extracts heat from the atmosphere. This causes liquid refrigerant passing through the thermodynamic panel 28 to be converted to a vapour.

Two arrangements of thermodynamic panel 28 are shown in Figures 8 and 9 respectively. Figure 8 shows a single thermodynamic panel 28 suitable for connection to the heat pump 26 to form the condenser heat exchange system 27. Figure 9 is an enhanced heat transfer arrangement comprising two thermodynamic panels 28 arranged in a superimposed relationship and operatively connected to each other so as to amplify the uplift and recovery time of the heat transfer.

The heat pump 26 includes a compressor pump 41, an adjacent expansion unit 42, a filter 43 and an expansion valve 44. The thermodynamic panel 28 is operatively connected to the compressor pump 41. The refrigerant gas vapour is compressed by the compressor pump 41 thus causing the temperature of the vapour refrigerant to rise. The adjacent expansion unit 42 allows for changes in volume.

The hot vapour refrigerant then passes through the tubular coil heat exchanger 13 around the outer periphery 12 of the cylinder 10. The heat of the refrigerant passes to the cylinder 10, which in turn results in heating of the water within the cylinder 10.

The now cooler, refrigerant, is in a thermodynamic state known as a saturated liquid. Under the circulatory effect, of the compressor pump 41, the now cooler, saturated, liquid refrigerant, enters the filter 43 and then passes to the expansion valve 44, where it undergoes an abrupt reduction in pressure, which results in the adiabatic flash evaporation of part of the liquid refrigerant. This serves to lower the temperature of the liquid and vapour refrigerant mixture, to the extent that it is now colder again, as it passes back to the thermodynamic panel 28. The whole cycle is then repeated. A display 45 shows the temperature of the hot water in the cylinder 10 via electronic communication with a temperature sensor located within a pocket in the cylinder 10 (neither visible in the Figures).

The apparatus can be used to replace the cylinder in existing water plumbing systems.

Claims

1. Heating apparatus comprising: a potable water cylinder; a first heat exchanger comprising a tubular coil wound around and in thermal contact with the outer periphery of the cylinder such that adjacent winds are in a spaced arrangement such that they do not engage each other; a compressor operatively connected to the first heat exchanger for the supply of compressed hot refrigerant thereto to enable heat to be transferred from the refrigerant to water within the water cylinder; an expansion valve that receives cooled liquid refrigerant from the first heat exchanger; and a second heat exchanger, comprising a roll bond aluminium thermodynamic panel, that receives cool refrigerant from the expansion valve and is in thermal communication with an environmental heat source.

2. Heating apparatus as claimed in claim 1 wherein pipe forming the tubular coil is substantially D-shaped in cross section.

3. Heating apparatus as claimed in claim 1 or claim 2, wherein the cylinder and first heat exchanger are housed in a casing and the second heat exchanger is connected thereto by refrigerant pipes.

4. Heating apparatus as claimed in claim 3, wherein the cylinder casing is generally square in cross section.

5. Heating apparatus as claimed in claim 3 or 4, wherein the second heat exchanger is mounted on the cylinder casing.

6. Heating apparatus as claimed in claim 5, wherein the apparatus is portable.

7. Heating apparatus as claimed in any of the preceding claims, wherein the second heat exchanger includes a second thermodynamic panel in thermal communication with an environmental heat source to heat refrigerant passing therethrough.

8. Heating apparatus as claimed in claim 7, wherein the second heat exchanger comprises a thermodynamic double panel having a pair of single evaporator heat exchangers overlaid and joined by pipework.

9. Heating apparatus as claimed in claim 3, further comprising thermal insulation around the cylinder to enhance the thermal efficiency ofthe apparatus, wherein the first condenser heat exchanger tubular coil is encapsulated in its position around the water cylinder with thermal conductivity paste in the regions of contact between the cylinder and the tubular coil, thermal foil wrapped around the tubular coil and integral hot water cylinder with its reflective side facing toward the tubular coil and cylinder, and insulation foam between the first condenser heat exchanger and the casing.

10. The heating apparatus as claimed in any of the preceding claims, which also includes, in this order, one or more of an accumulator or receiver, a filter, a drier, a sight glass or moisture indicator.