GB2467812A

GB2467812A - Fluid conditioning arrangement

Info

Publication number: GB2467812A
Application number: GB0916217A
Authority: GB
Inventors: Karina Torlei; Matthew Holloway; Daniel Becerra; William Linsey Penfold
Original assignee: ARTICA TECHNOLOGIES Ltd
Current assignee: ARTICA TECHNOLOGIES Ltd
Priority date: 2009-02-11
Filing date: 2009-02-11
Publication date: 2010-08-18
Also published as: GB0916217D0

Abstract

A fluid conditioning arrangement comprises a primary and secondary heat exchanger configured to cool and/or heat a fluid, a controller for operating the secondary heat exchanger when the primary heat exchanger fails to cool and/or heat the fluid at a predetermined acceptable level, and the primary heat exchanger is a phase change material (PCM) based heat exchanger. The secondary heat exchanger may be a vapour compression cycle based air conditioning system, a heat pump, an absorption chiller or a solar based heat exchanger (fig 4), and it may incorporate a liquid store suitable for cryogenic cooling (fig 2), an evaporative cooler (fig 5) or Peltier cooler (fig 13). The PCM may be a plate, shell and tubular heat exchanger. Two types of PCM may be used for both heating and cooling (fig 8). Valves 14, 15 may be used to regulate the amount of fresh and recirculated air and valves 12, 16 may be used to regulate the flow of air into a room or to the outside. A pressure sensor (75, fig 10) may be used to adjust the speed of a fan (74).

Description

FLUID CONDITIONING ARRANGEMENTS AND/OR PHASE CHANGE MATERIAL MODULES

Field of the Invention

The invention relates to fluid conditioning arrangements, phase change material modules and/or components operated in conjunction with these.

Summary of the Invention and Prior Art Known to the Applicant(s) The following prior art documents are acknowledged: DE102007013779, U55647225, U57124594, U57162878, US5255526, U57363772, U55211029, U54916916, U55647225, U55860287, and U56393861.

One of the objects of the invention is to try to improve primarily PCM based fluid conditioning arrangements in terms of performance and reliability.

Summary of the Invention

In a first broad independent aspect, the invention provides a fluid conditioning arrangement comprising a primary heat exchanger configured to cool and/or heat fluid; a secondary heat exchanger configured to cool and/or heat fluid; and a controller for operating said secondary heat exchanger when said primary heat exchanger fails to cool and/or heat the fluid at a predetermined acceptable level; wherein said primary heat exchanger is a phase change material (PCM) based heat exchanger. This configuration improves the overall performance of the system as it allows the PCM heat exchanger to do most of the work of cooling and/or heating. For example, PCM can be used to store cool energy from the night to provide space cooling during the day, because these cycles rely on natural fluctuations and the weather, on occasion the night time temperatures may not be low enough to cool the PCM. In this situation, a back up or booster system can be used to provide additional cooling of the night or daytime air, improving performance and reliability while minimising energy usage. It allows the arrangement to operate over a wide variety of outside temperature conditions. It also further improves the energy efficiency when compared to conventional systems.

In a subsidiary aspect, said secondary heat exchanger is selected from: a vapour compression cycle based air conditioning system, a heat pump, or an absorption chiller.

In a subsidiary aspect, the secondary heat exchanger incorporates a liquid store suitable for cryogenic cooling. This combination further reduces the energy requirements for the secondary heat exchanger. It is particularly advantageous when the use of the secondary heat exchanger is relatively infrequent.

In a further subsidiary aspect, said secondary heat exchanger incorporates an evaporative cooler. This combination synergistically reduces the energy requirement for an achievable level of cooling.

In a further subsidiary aspect, the evaporative cooler incorporates a housing with an air intake; a corresponding air outlet; a liquid inlet; a corresponding liquid outlet; and a wicking surface. It can also improves the heat exchange between an evaporative cooler and a PCM heat exchanger due to the benefits of a fluid based heat exchanger when compared to an air based heat exchanger.

In a further subsidiary aspect, said secondary heat exchanger incorporates a Peltiere cooler.

This configuration is also particularly advantageous in that the secondary heat exchanger is only required infrequently. It also lends itself to a particularly compact solution. In a further subsidiary aspect, said secondary heat exchanger exchanges heat with a liquid which then exchanges heat with the PCM of said primary heat exchanger. This configuration has the advantage of using a heat transfer fluid with a higher capacity than air. This kind of system may however still be used to provide fresh cooled air.

In a further subsidiary aspect, said primary heat exchanger incorporates one or more units housing PCM; wherein said housing incorporates a PCM tank. This configuration simplifies the construction when compared to multiple packs in a housing.

In a further subsidiary aspect, said tank incorporates insulated sides and at least one side without insulation in order to enhance convection through said side. This configuration is particularly advantageous in order to release cooling/heating into a room.

In a further broad independent aspect, the invention provides a phase change material (PCM) module comprising a number of PCM packs; a housing for thermally insulating said number of PCM packs from a module's surrounding medium; said packs being in the form of a panel with an upper surface, a lower surface and relatively narrow lateral sides; wherein a plurality of troughs in at least either the upper or lower surfaces of the panel are provided to allow fluid to flow through the module for heat exchange with PCM. This configuration reduces the number of components required in order to provide the spaces in a stack of PCM packs.

In a further broad independent aspect, the invention provides a phase change material (PCM) module comprising a number of PCM monoliths or tubes; a housing for thermally insulating said number of PCM monoliths from a module's surrounding medium; and gaps being formed between a stack of said monoliths or tubes in said module to allow fluid to flow through the module for heat exchange with the PCM. This configuration allows a stack of such monoliths or tubes to achieve improved heat exchange with a heat transfer fluid. It also provides a particularly robust stack which is also particularly straightforward to assemble whilst employing relatively lightweight individual components.

In a further subsidiary aspect, said monoliths are hexagonal in cross-section. This allows the individual monoliths to be stacked in a uniform manner.

In a further broad independent aspect, the invention provides a phase change material (PCM) module comprising a number of PCM packs; a housing for thermally insulating said number of PCM packs from a module's surrounding medium; and conduits passing through said PCM packs to allow fluid to flow through the module for heat exchange with the PCM.

This configuration further improves the efficiency of the heat exchange for certain applications.

In a further broad independent aspect, the invention provides a fluid conditioning arrangement comprising a first heat exchanger configured to heat and/or cool fluid; and a second heat exchanger configured to cool and/or heat fluid; wherein said one of said heat exchangers is a phase change material (PCM) based heat exchanger and the other is an evaporative cooler. This configuration is also particularly advantageous in terms of energy efficiency when compared to conventional heat pumps and conventional combinations of heat pumps and evaporative coolers.

In a further broad independent aspect, the invention provides a fluid conditioning arrangement comprising a first heat exchanger configured to cool and/or heat fluid; and a second heat exchanger configured to cool and/or heat fluid; wherein said one of said heat exchangers is a phase change material (PCM) based heat exchanger; and the other is a Peltiere cooler. This configuration is also particularly advantageous in terms of efficiency when compared to conventional combinations of heat pumps and PCM material. It lends itself to the Peltiere acting as a booster system which is particularly advantageous when the demand for the use of the Peltiere cooler is relatively infrequent.

In a further broad independent aspect, the invention provides a fluid conditioning arrangement comprising a first heat exchanger configured to cool and/or heat fluid; and a second heat exchanger configured to cool and/or heat fluid; wherein said one of said heat exchangers is a phase change material (PCM) based heat exchanger; and the other is a solar based heat exchanger.

Brief Description of the Figures

Figure 1 shows a fluid conditioning arrangement in schematic cross-sectional view of an embodiment incorporating primarily a PCM module and secondarily a refrigerating unit.

Figure 2 shows a schematic cross-sectional view of a PCM based fluid conditioning arrangement with a cryogenic booster.

Figure 3 shows a schematic of a fluid conditioning arrangement where the heat transfer between a first fluid conditioning arrangement and a second fluid conditioning arrangement is achieved by using fluid instead of air.

Figure 4 shows a schematic of the central unit in a fluid conditioning arrangement in accordance with a further embodiment.

Figure 5 shows a fluid conditioning arrangement incorporating an evaporative unit.

Figure 6 shows a module which has no PCM material.

Figure 7 shows a PCM tank.

Figure 8 shows a PCM module with a fluid based heat exchange.

Figure 9 shows a further embodiment with a PCM module of the kind shown in Figure 8.

Figure 10 shows a control unit.

Figure 11 shows a PCM module.

Figure 12 shows a system with a couple of modules.

Figure 13 shows a Peltiere booster.

Figures 14 show PCM packs in a plurality of views.

Figures 1 5 show PCM monoliths in a plurality of views.

Figures 16 show a plurality of PCM packs with hexagonal components throughout.

Figures 1 7 shows PCM packs in a plurality of views.

Figures 18 show PCM packs with semi-circular troughs in a plurality of views.

Detailed Description of the Figures

Figure 1 shows a fluid conditioning arrangement generally referenced 1. The air conditioning arrangement 1 incorporates three air inlets respectively referenced 2, 3 and 4.

Through inlet 3 fresh air from outside is drawn into the housing 5 by a fan or pump 6. It is important to note that whilst the embodiments of the invention are primarily illustrated for cooling air, other fluids may also be cooled and/or heated using these systems. In a conventional mode of operation the air is fed through a PCM heat exchanger 7 so that any heat in the air may be absorbed by the PCM before exiting the housing through outlet 8.

The arrangement may preferably be equipped with a controller which may be configured to measure the temperature of the PCM in order to determine the extent of cooling that may be achieved by the heat exchanger. If due to the conditions surrounding the heat exchanger, a booster is required, as for example, the PCM heat exchanger fails to be effective or the incoming fluid temperatures are not hot/cold enough, the controller switches on the booster. In this configuration, the booster incorporates a heat pump with a cold heat exchanger and condensation tray 9 located in the path of the air to be cooled and a hot heat exchanger 10. The heat pump would incorporate the necessary compressor and expansion valve or an absorption chiller. Block 11 illustrates its location between hot heat exchanger 10 and cold heat exchanger 9. If the booster is needed during the day, the controller would cause the provision of air flow over the hot heat exchanger and would cause valve 12 to be closed whilst valve 13 would be opened. An additional fan would pump air through inlet 4 when the arrangement would be operating in the booster mode of operation. Valve 14 is provided to allow re-circulated air through the arrangement.

Valve 1 5 is provided to allow and/or block dependent upon the operator's selection of the intake of fresh air to the arrangement. The invention also envisages systems without the valves or with fewer valves dependent upon the level of control required. Valve 16 is provided in the outlet to the room.

Figure 2 shows a fluid conditioning arrangement generally referenced 17 with a booster arrangement employing a liquid carbon dioxide or nitrogen store to provide cooling as it expands in the cold heat exchanger 18. Other than for this booster arrangement, the fluid conditioning arrangement is similar to the arrangement shown and described in detail in Figure 1. Instead of incorporating an air supply to the hot heat exchanger of the booster, the arrangement incorporates an outlet 20 to allow air back outside. At night, valve 15 opens and valve 14 closes to let in night air. The controller of the arrangement causes the booster arrangement to operate if the night air is not cold enough to freeze the PCM.

Valve 16 closes and valve 12 opens if the room temperature gets too cold. During the day valve C closes and valve D opens to let air into the room. If it is cold outside then valve 1 5 opens and valve 14 closes so less air is re-circulated and vice versa.

Figure 3 shows a further fluid conditioning arrangement generally referenced 21 with a booster unit 22 and a plurality of PCM units 23, 24 and 25. Heat transfer fluid lines are provided such as heat transfer fluid line 26. A return line 27 is provided. When the control unit identifies that the PCM stores which are positioned around the building have failed to deliver the desired cooling effect, the booster system 22 is switched on. The booster incorporates a heat exchanger 28 between two fluids. An air intake 29 draws air across the heat exchanger for extra cooling. A valve 30 is provided between heat exchanger 28 and optional booster system 31. A further air intake 32 allows air into the optional booster system. An air outlet 33 exhausts air from the booster. The optional booster unit 31 may take the form of either of the systems of Figure 4 and Figure 5.

Figure 4 shows a central unit for heating. This system incorporates an external solar collector 34 which is in fluid communication with a drain-off tank 35 which is configured to prevent water freezing in the solar collector at night. A further fluid line 36 is provided between tank 35 and a hot water tank 37. A boiler 38 is located in series with the hot water tank. The solar collector provides hot water or cooling by working as a radiator at night. During the day, the solar collector provides hot water which can be boosted by the boiler if needed and stored in the hot water tank. Because much of the heat is provided during the day and heating is required at night in residential buildings, the heat may be stored in the latent heat stores around the building. In the summer, the system can still store hot water in the tank for showers but at night cooling from outside can be fed to the PCM tanks in the room by bypassing the hot water tank.

Instead of employing the central unit of the kind described in Figure 4, an evaporative central unit generally referenced 39 may be employed. This unit incorporates housing 40, an air inlet 41 equipped with a filter, a single or a multiple stage evaporative cooler with a wicking mesh 42, an exhaust air outlet 43 and a fan 44 to cause the flow of air through the unit. A first heat transfer line 45 is employed to return warm water to the unit whilst a heat transfer line 46 is employed to allow cold water to circulate to units in the room.

This configuration is particularly advantageous because it allows the working fluid, i.e. the water from the evaporator to cool the PCM rather than the wet air to be used by an evaporative cooler which increases the humidity of a room.

Instead of, or in addition to, the PCM units of Figure 3, a unit 47 as shown in Figure 6 may be employed. This unit may receive and return fluid from a central system by heat transfer line inlet 48 and outlet 49. Housing 50 incorporates an air inlet 51 equipped with a filter.

An air outlet 52 is provided at an opposite side of the housing 50. A fan 53 draws the air through the unit.

Figure 7 shows an alternative unit which may be placed in a building and which may receive and return fluid from a central system. Unit 54 incorporates a housing 55 containing PCM 56. One of the sides of the unit such as side 57 incorporates no insulation so that cooling and/or heating may be released on one or more sides.

Figure 8 shows a unit 58 with a housing 59 for containing spaced apart PCM components such as component 60. The unit incorporates an air inlet 61 equipped with a filter and an air outlet 62 with a fan 63. The PCM components may be plate-like, spherical, shell-like and tubular heat exchangers etc. A heat transfer line 64 forms a winding pattern in close proximity to the PCM in order to optimise heat transfer. The invention also envisages employing two different kinds of PCM with different melting temperatures for heating and cooling. The heating range may be 40 to 600 Degrees Celsius whilst the cooling range may be 15 to 32° Celsius.

Figure 9 shows a further unit generally referenced 65 with a housing 66 containing a plurality of PCM components such as component 67. The housing 66 incorporates an air intake 68 and an air outlet 69. A valve 70 is provided in a duct to regulate whether air is received from outside or re-circulated from the room. A further valve 71 is provided to regulate whether the air goes back outside or whether it goes into the room. When this system is combined with ventilation, it has the advantage of using a heat transfer fluid line 72 with a higher heat capacity than air. It is particularly advantageous when used to freeze PCM whilst still providing fresh air.

Figure 10 shows a control unit which may be used to assess the requirements of a system.

A valve 73 is provided to determine whether the air is re-circulated from the building, taken from outside, or taken from a booster. A fan 74 is provided to draw air through the system. A pressure sensor 75 determines the pressure in order to adjust the fan speed. If the pressure in the duct 76 increases, then the fan is caused to slow down. The pressure sensor may incorporate a pitot tube or any other component suitable for determining a value which may then be equated to the pressure in the duct.

Figure 11 shows a further unit generally referenced 77 with a stack of PCM packs such as pack 78. Unit 77 incorporates a housing 79 for insulating the contents of the unit from the outside heat. Dampers or valves 80 are provided in the inlet duct. A control unit 81 is provided to determine how much air flows through the unit dependent upon how much cooling is needed. An operator interface may be provided to adjust the level of cooling needed.

Figure 12 shows two rooms 82 and 83, each incorporating a PCM module respectively referenced 84 and 85. A duct 86 communicates air to the PCM modules. A control unit which may be of the kind shown in Figure 10 is generally referenced 87. Upstream from the control unit, a booster unit 88 is provided. The booster unit may be of the kind shown in the previous embodiments. These control and PCM modules can be those of figures 10 and 11.

The booster may take the form of a Peltiere booster which may be of the form shown in Figure 13 where a unit 89 has a hot side 90 and a cold side 91. The cold side 91 incorporates a condensation tray 92 or a condensation catcher 93 in order to allow condensation to run off.

Figure 14 shows a PCM unit 94 incorporating PCM packs 95. Each pack incorporates a plurality of recess portions 96 running the length of the packs. The PCM packs incorporate PCM material and an appropriate non-permeable envelope 97. The recesses are formed in the envelope. The recesses extend only partially across the depth of the packs. The recesses reduce in width progressively as the depth of the recess increases. A flat base face 98 is provided at the bottom of each recess. The recess portions allow the circulation of fluid for optimum heat exchanging. Figure 14B shows the arrangement of Figure A in perspective view. Figure 14 C shows a cross-sectional view of a PCM pack, whilst Figure 14D shows a perspective view of a PCM pack.

Figures 15 show a PCM unit 99 with a plurality of hexagonal tubes 100. Each tube contains PCM material and is capped at both ends by a lid 101. By stacking a plurality of hexagonal tubes 100, a number of hexagonal ducts 101 are formed which may be used to allow heating fluid to circulate through the unit.

Figures 16 show views of PCM packs. PCM pack 102 with upper and lower surfaces 103 and 104 which are formed by a succession of recess portions such as recessed portion 105 which increases in width from a flat base portion 106. The recess portions are effectively half of a hexagon. There are provided protrusions 107 which are also effectively half of a hexagon. The PCM pack is formed as if it were formed by a plurality of side-by-side hexagonal tubes with the common faces such as face 108 removed so that the PCM material is distributed throughout the PCM pack. Thermal conductors may be provided between the upper surface 103 and the lower surface 104 in an alternative embodiment.

By stacking a plurality of PCM packs of this form as shown in Figure 6F channels for circulating fluid such as channel 109 are formed.

Figures 1 7 show PCM packs incorporating tubes at regular intervals extending through the PCM layer. Tubes 110 may be used to circulate cooling fluid as appropriate. A cap 111 allows access to the inside of the pack for filling the pack with PCM. A second cap 112 is also provided for facilitating the filing and emptying of the PCM pack.

Figures 18 show PCM packs in accordance with a further embodiment where the pack 113 incorporates a plurality of semi-circular, in cross section, troughs 114. The recesses or troughs are provided in both the upper surface 11 5 and the lower surface 116. The troughs in the upper surface are offset relative to the troughs of the lower surface. A trough in the upper surface is located opposite a flat outermost portion of the lower surface.

Claims

Claims 1. A fluid conditioning arrangement comprising a primary heat exchanger configured to cool and/or heat the fluid; a secondary heat exchanger configured to cool and/or heat the fluid; and a controller for operating said secondary heat exchanger when said primary heat exchanger fails to cool and/or heat the fluid at a predetermined acceptable level; wherein said primary heat exchanger is a phase change material (PCM) based heat exchanger.
2. An arrangement according to claim 1, wherein said secondary heat exchanger is selected from: a vapour compression cycle based air conditioning system, a heat pump, or an absorption chiller.
3. An arrangement according to claim 1, wherein said secondary heat exchanger incorporates a liquid store suitable for cryogenic cooling.
4. An arrangement according to any of the preceding claims, wherein said secondary heat exchanger incorporates an evaporative cooler.
5. An arrangement according to claim 4, wherein said evaporative cooler incorporates a housing with an air intake; a corresponding air outlet; a liquid inlet; a corresponding liquid outlet; and a wicking surface.
6. An arrangement according to claim 1, wherein said secondary heat exchanger incorporates a Peltiere cooler.
7. An arrangement according to claim 1, wherein said secondary heat exchanger exchanges heat with a liquid which then exchanges heat with the PCM of said primary heat exchanger.
8. An arrangement according to claim 1, wherein said primary heat exchanger incorporates one or more units housing PCM; wherein said housing incorporates a PCM tank.
9. An arrangement according to claim 8, wherein said tank incorporates insulated sides and at least one side without insulation in order to enhance convection through said side.
10. A phase change material (PCM) module comprising a number of PCM packs; a housing for thermally insulating said number of PCM packs from a module's surrounding medium; said packs being in the form of a panel with an upper surface, a lower surface, and relatively narrow lateral sides; wherein a plurality of troughs in at least either the upper or lower surfaces of the panel are provided to allow fluid to flow through the module for heat exchange with the PCM.
11. A phase change material (PCM) module comprising a number of PCM monoliths; a housing for thermally insulating said number of PCM monoliths from a module's surrounding medium; and gaps being formed between a stack of said monoliths in said module to aLlow fluid to flow through the module for heat exchange with the PCM.
12. A module according to claim 11, wherein said monoliths are hexagonal in cross-section.
13. A phase change material (PCM) module comprising a number of PCM packs; a housing for thermally insulating said number of PCM packs from a module's surrounding medium; and conduits passing through said PCM packs to allow fluid to flow through the module for heat exchange with the PCM.
14. A fluid conditioning arrangement comprising a first heat exchanger configured to cool and/or heat fluid; and a second heat exchanger configured to cool and/or heat fluid; wherein said one of said heat exchangers is a phase change material (PCM) based heat exchanger; and the other is an evaporative cooler.
1 5. A fluid conditioning arrangement comprising a first heat exchanger configured to cool and/or heat fluid; and a second heat exchanger configured to cool and/or heat fluid; wherein said one of said heat exchangers is a phase change material (PCM) based heat exchanger; and the other is a Peltiere cooler.
16. A fluid conditioning arrangement comprising a first heat exchanger configured to cool and/or heat fluid; and a second heat exchanger configured to cool and/or heat fluid; wherein said one of said heat exchangers is a phase change material (PCM) based heat exchanger; and the other is a solar based heat exchanger.
1 7. A fluid conditioning arrangement and/or modules substantially as hereinbefore described and/or illustrated in any appropriate combination of the accompanying text and/or figures.