Field of the Invention

This invention relates to an air conditioning system. Bac<ground of the Invention

Air conditioning systems are used worldwide to control air temperature, usually in an indoor space such as a home, shop or supermarket. A typical system uses a refrigeration cycle whereby heat is transported from the indoor space to the outside. A circulating refrigerant vapour is compressed by a compressor which raises its temperature. It is then routed through a condensing coil which cools and condenses the vapour into liquid using cool air passing over the coil. The heat is carried away by the air. The liquid is then routed through an expansion valve which reduces the pressure, lowering its temperature, and the colder liquid passes to an evaporator coil. A fan blows the air tc be cooled over the evaporator- causing the cool refrigerant material to cool further. The warm air is therefore cooled.

Sucn systems therefore require a gas compressor, making the system relatively bulky and also energy inefficient. The type of refrigerant used is typically a hydro chlorofluorocarbon (HCFC) , which substance is relatively expensive and known to contribute to climate change.

It is^ an aim to provide an improved air conditioning system. SuitiT.ary of the Invention

A first aspect of the invention provides an air conditioning system, comprising: a housing having first and second chambers, with an air inlet and air outlet to allow the respective ingress and egress of air to and from the first chamber; a container within the first chamber which contains a quantity of refrigerant gas; a fan or the like for creating in the first chamber a current of air generally towards the gas container; a pipe or series of pipes that extend from the gas container at a first location through a wall into the second chamber, passing adjacent a defrosting means in the second chamber, and returning into the first chamber and to the gas container at a second location; a first valve arranged in use to release a quantity of gas from the gas container into the p pe when the gas pressure reaches a predetermined level thereby to lower the temperature of the contained gas and at least part of the container, and a seccnd valve which selectively permits gas to re-enter said gas container to increase the pressure within.

The refrigerant gas may be refrigerant-grade carbon dioxide, e.g. CO2 R744. In some embodiments, propane may be used. As an alternative to a fan, any form of device _. , arrangement or systeir. for creating an air current can be employed.

The system may further comprise a secondary air cooling unit or coil containing a quantity of refrigerant gel or liquid which is located within the first chamber, adjacent the gas container, between i ^~ and the air outlet.

The defrosting means may comprise a fan or the like, e.g. an alternative device, arrangement or system for creating a current of air, arranged in use to create in the second chamber a current of air in the direction of the pipe and an extractor cutlet. The air can be at ambient temperature or air that is warmed by a heater. In some embodiments, the defrosting means may comprise a heater. In some embodiments, a heat exchanger may be associated with the defrosting means, or part thereof, which feeds back to the gas container. The first valve can be a pressure control valve (PCV) .

The second valve may be arranged so as to permit gas to reenter the gas container when the gas pressure therewithin reaches a predetermined lower level.

The system may further comprise a gas supply tank for supplying gas to the pipe re-entering the gas container.

The gas container may comprise a plurality of diffuser elements in the region of its second location.

The gas container may comprise a metallic cooling coil element at or near its base.

The system nay comprise plural gas containers. Each gas container may have its own pressure release valve and outlet pipe fcr releasing gas into the common p pe or series c pipes which enter the second chamber. The system may be arranged such that a further valve is provided upstream from, the location where the plural outlet pipes join the common pipe or series thereof. The system may be arranged such that the pressure release valves of the containers are selectively controlled so that pressure is released from only a subset of the containers. The system may be arranged such that the pressure release valves and re-entry valves are controlled to release and increase pressure in different con ^t ainers according to a predetermined order, e.g. using a control system. A second aspect of the invention provides an air conditioning system, comprising: first and second chambers, the first chamber having an air inlet and cutlet, a means of generating an airflow within the first chamber towards the outlet, and, disposed in the first chamber, a cooling element containing refrigerant, which cooling element is connected to a pipe or pipes providing a fluid pathway which extends into the second chamber which is arranged to have, in use, a raised temperature relative to the first chamber, and then back into the first chamber where it extends back to the cooling element, one or more valves being provided in the fluid pathway to control (i) -he venting of refrigerant into the fluid pathway and (ii) the input of refrigerant back into the cooling element.

A third aspect of ^~ he invention provides an air conditioning system, comprising: a first, cooling chamber; and a second, defrosting chamber, wherein the first chamber comprises a fan for generating an air current towards one or more cooling containers within the first chamber, the or each container being located between the fan and an air outlet of the first chamber and comprising a refrigerant gas the pressure of which is adjustable by means of a control system arranged to detect an upper threshold pressure to effect venting of refrigerant gas to a container outlet, and to detect a lower threshold pressure to effect ingress of refrigerant gas through a container inlet, and wherein a pipe or pipe network extends between the container outlet and intlet, and at least partially through the defrosting chamber, thereby tc carry the vented gas into the defrosting chamber which is arranged to have a raised temperature so that in use any solidification of the vented refrigerant gas within the pipe(s is returned to a gaseous state prior to being returned by the control system to the container through its inlet. In some embodiments, the gas container is provided in two parts divided by a wall and with a valve controlling passage of gas between the twc parts. One part may be in communication with a heat exchanger associated with the defrosting means, so that heat generated by the heat exchanger is transferred to said first part to raise the temperature and therefore the pressure. This may be used as a means to cause the valve to the outlet pipe or pipes to open and move the gas towards the defrosting part. The other part of the gas container can be arranged to receive gas from the pipe or pipes as it leaves the defros ing par .

In some embodiments, no mechanical compressor, .e. of the conventional sort which operates by reducing the physical volume containing the gas, is required.

A fourth aspect provides a method, comprising: in a first charber of an air conditioning unit, moving a current of air over a container containing a quantity of refrigerant gas and towards an exit port; raising the temperature and pressure of the contained gas; releasing a quantity of the contained gas responsive to the raised temperature and pressure; transporting the released gas towards a second, separate chamber whereby the temperature is such as to maintain, or return, the released gas in a gaseous state; and subsequently returning a quantity of the gas back into the container.

Brief Description of the Drawings

The invention will now be described, by way of non-limiting example, with reference to the accompanying drawings, in whic : Figure 1 is side-sectional view of a first embodiment air conditioning system according to the invention;

Figure 2 is a perspective view of a gas container of the Figure: 1 system, with the interio-r visible;

Figure 3 is a perspective view of part of an alternative air conditioning system which employs plural gas containers;

Figure 4 is a pla view of the plural cylinders shown in Figure 3, in relation to an air outlet; and

Figure 5 is a partial side-sectional view of a second embodiment air conditioning system according to the invention.

Detailed Description of Preferred Embodiments (s }

A first embodiment a r conditioning (AC) system 1 is shown in Figure 1. The AC system 1 is shown frcm the side, fixed to a wall 3.. with the room inferior to the left-hand side of the wall, and the exterior to the right-hand side. The AC system 1 comprises two distinct chambers, namely a cooling chamber 5 and a defrosting chamber 7. The two chambers 5, 7 are mechanically connected, or integrally formed, but separated by an insulating wall .

The cooling chamber 5 comprises separate air inlet and outlet ducts 11, 13. As is conventional, the AC system 1 is fitted to the wall 3 with the inlet duct 11 positioned generally above the outlet duct 13 owing to the fact that cooled air exiting the outlet duct 13 will rise as it gets warmer and some will re-enter the system via the inlet duct 11. Cooling is primarily effected within the ccoling chamber 5 by a primary cooling element, in the form of one cr more containers 15, which contain a quantity of refrigerant grade CO2 R744 in gas form. The container (3) 15 are positioned at or near the bottom of the cooling chamber 5, relatively close to the outlet duct 13. In overview, when the gas reaches a predeterm ned pressure (due prinarily to ambient temperature) some gas is vented to pipework which reduces the pressure of the gas in the container 15 and therefore reduces the temperature of the gas. A fan 17 or similar device is positioned adjacent the inlet duct 11 and operates to generate airflow towards the container (s) 15 where it is cooled before leaving the outlet duct 13. Although not essential, a secondary coding element 19 is provided between the priir.ary cooling element 15 and the outlet duct 13; this secondary element may be in the form cf a coil or similar unit, having caps or apertures therewithin to allow air to pass through to the outlet duct 13. The secondary element 15 is a sealed unit containing refrigerant liquid or gel, and is pcsitioned very close to the primary element 15 so that it freezes in use by the action of the cooling gas in the container 15, and therefore provides a means of cooling the exiting air even if the gas -emperature rises.

Particulate air filters 21, 23 are mounted over the inlet and outlet ducts 11, 13.

Each primary cooling container 15 is a metallic cylinder with an. outlet 25 and an inlet 27 for the controlled egress and ingress of gas. The outlet 25 is connected to a discharge pipe 31 via a controllable expansion valve 25, e.g. a pressure control valve (PCV) . The expansion valve 25 is controlled electronically to open and close depending on the sensed pressure within the gas cooling container 15. Initially, the gas pressure, is assumed to be at a reference level. The gas pressure will be raised by ambient temperature, which will be room temperature in warmer climates, or by the application of heat, e.g. by a heating element or similar source. When the pressure reaches an upper threshold, the expansion valve 25 is opened. When the pressure (or temperature) returns to below another, lower, threshold, the expansion valve 25 is closed. Opening of the expansion valve 25 results in venting of the CO2 gas into the discharge pipe 31. The opening and closing control may be effected according to alternative criteria.

The discharge pipe 31 forms part of a pipework system that passes through the insulating wall 9 into the defrosting chamber 7 as shown. A tight seal surrounds the pipe 31 as it passes through the wall 9. More specifically, the discharge pipe 31 is in fluid communication with, and extends to a defrosting coil 33, which itself connects to a return pipe 35 which passes back through the wall 9 into the cooling chamber 5. In use, as vented CO2 gas passes into the defresting chamber 7, it tends to solidify in a phase-change process called deposition. In order to reverse the phase-change back into gas ( sublimaticn) another fan 37 (which may be associated with a heater) blows warmer air over zhe defrosting coil 33 and the CO2 gas flows onwards through the return pipe 35. The temperature required to achieve this can be found by routine testing, but Applicant has found a temperature of between 3 and 10 degrees centigrade :o be appropriate, In the return pipe 35 is a non-return valve 39, e.g. a solenoid-controlled valve, which prevents backflow of gas. A further valve 45 is arranged to controllably return a quantity of the vented gas back into the primary cooling container 15, thereby returning the gas pressure to its prior (i.e. reference) level. At the time the valve 45 is opened, the expansion valve 25 is usually closed.

It will therefore be appreciated, that no compressor of the type employed in conventional air conditioner units is required, allowing the AC system 1 to be lighter, less bulky and more efficient. Here, we take advantage of the falling pressure/temperature effect of venting gaseous refrigerant CO2 which is then defrosted from its solid state and returned in a controlled manner to the previous reference pressure, or thereabouts. The AC system 1 offers particular advantages in warmer climates whereby the ambient temperature will tend to raise the pressure of the gaseous refrigerant C02 in the gas cooling container 15 to initiate the venting phase.

One or more sensors (not shown) are provided in the gas cooling container 15 to de-ermine in real-tine, or near realtime, the current gas pressure. A computer or electronic control system is provided, and is in signal communication with the valves 2S, 45 to control the opening and shutting of said valves dependent on the sensed pressure. Al ^t ernatively, a separate control system can be provided for each valve 29, 45. The warm air flow created by the second fan 37 exits the defrosting chamber through a louvered outlet 41 which may have a particulate fil er 43.

As shown in Figure 1, a supply tank 36 for the refrigerant CO2 is provided in the defrosting chamber 7 part of the loop, between the non-return valve 39 and the valve 45. Within the tank 36, the refrigerant may be stored for a time as a liquid, possibly for just a short time, but it will convert back into gas before it re-enters the container 15 to top-up the pressure.

Referring to Figure 2, the cooling container 15 comprises a cylindrical metal body 51 having an upper portion 53 which houses the refrigerant CO2 gas, and a base portion 55 within which is arranged a metallic cooling coil 56. The upper end of the body 51 comprises an aperture 57 to which the valve 25 is attached, and the lower inlet 27 is provided close to the base portion 55, which is connected to the return pipe 35. In order to reduce noise that will otherwise tend to occur from gas re-entry through the lower inlet 27, a plurality of vertical diffusers 61 extend from the upper surface of the base portion 55. These serve to diffuse the incoming gas to reduce noise overall. Alternative forms of diffusers can be used.

Referring now to Figures 3 and 4, in ano ^t her embodiment, multiple such cooling containers 15 can be provided in the cooling chamber 5. These are labelled 15A, B and C, with their respective outlet valves 25., outlet pipes 51, and inlet valves 24 suffixed accordingly. The outlet pipes 31A-C feed tc a combining pcin ^~ 65 connected to the common pipe 31' . Similarly, a dividing point 67 splits incoming gas from pipe 35 into three separate inlet pipes which return gas to respective ones of the cooling containers 15A-C. Otherwise, the AC system 1 remains identical to that in Figure 1.

In terms of operation, any combination of the three cooling containers 15A-C can be used. Fcr example, where significant cooling is required, all three can be switched on. Where less cooling is required, just a subset, e.g. the centre container 15B may be switched on. Where cooling to just cne side cf a room is required, the left or right -hand one may be the only cooling container 15A-C switched on. Where more than one cooling container 15A-C is employed, the control system may operate so that different containers vent in a phased manner, e.g. in the manner of pistons in a car engine, with one venting whilst the other (s) are closed-off and/or receiving feed-back gas. Figure 4 shows the Figure 3 embodiment from above, indicating the relative positions of the multiple container 15A-C arrangement in relation to the outlet duct 13. It will also be noted that the secondary coil 19 has apertures or slots 0 therewitnin to permit airflow to the outlet duct 13.

Figure 5 is a second embodiment air conditioning system 100. The view is partial,, in comparison to Figure 1, with the different parts shown, but otherwise the arrangement is the same oo closely similar, e.g. in terms o there being two distinct chambers either side of an insulating wall.

In this case, in the primary cooling chamber 5 is a cooling container 101 which is in two parts, namely an upper part 103 and a lower part 105. The lower part 105 is larger than the upper part 103 by a ratio of about 3:1. At the top of the upper part 103 is a pressure control valve fPCV) 107 which is in fluid connection to a pipe 109 which passes through the insulating wall and into the secondary, defrosting chamber 7 towards a secondary defrosting coil 110. The upper and lower parts 103, 105 are divided by a wall 1C6 having a check valve 108 configured in use to permit gas to pass from the lcwer part to the upper part when its temperature and pressure reaches a predetermined level.

Adjacent the upper portion of the secondary coil 110 is a heat exchanger 111. A pipe (or start line) 113 extends from the heat exchanger 110 back to the cooling container 1C1, particularly the upper part 103. The lower portion of the secondary coil 110 continues to a pipe 115 which feeds to a liquid, tank 117. The liquid tank 117 is connected by a pipe 115 to an expansion valve 121 which m turn is connected to the lower part 105 of the primary ccolmg chamber 5. There may or may not be a non-return valve before the liquid tank 117 as in Figure 1.

In this embodiment, to start operation the cooling chamber 5 moves a mass of refrigerant through pipe 139 not by compressing it to a predetermined level using a heater below the cooling chamber but rather by use of the heat exchanger 111 to raise the temperature in the defrost ceil' s upper part 103 and also the vacuum pressure created on the upper side of PCV 107 which causes it to open at an appropriate pressure differential. Mere specifically, the upper part of the secondary coil 110 is initially heated, e.g. by an external heater, so that refrigerant therein is heated and fed back to the upper part 103 via pipe 113. This causes latent heat vaporisation. The increased pressure in said upper part 103 and the vacuum cn the other side of the PCV 107 causes it to open at a predetermined level.

During running, heat will continue to be created in the defrost chamber 7 and this will be fed directly to the liquid tank 117. The liquid tank 117 is connected to the expansion valve 121 so that as pressure continues ^~ o rise, said valve 121 will at a predetermined pressure open tc expand a relatively small amount of refrigerant liquid into the lower part 105 of the cooling container 101.

As before, the defrost chamber 7 can be provided with a fan (shown in dotted lines) to expel sone cf the heat and keep it within acceptable limits.

Regarding he two part cooling container 101, within the larger, lower part 105, latent heat cf fusion (phase change) takes place. Within, the smaller, upper part 103, latent heat of condensation takes place. Whilst the container 101 is here formed as a single unit, in theory two separate container units could be connected.

A secondary coil (see reference numeral 19 in Figure 1) is not necessary, but in some embodiments may be provided. This is one way of transferring cool air from the cooling chamber 5 into the rocm to be cooled. This can be done by water or an air handling method.

In summary, in comparison to the first embodiment, whereby the cooling container is heated to initially increase internal pressure of refrigerant, in this embodiment heat from the defrost chamber is fed back to raise the temperature within the cooling container's upper part 103 and also to raise the vacuum pressure tc move the latent heat of condensation. This starts the running procedure by opening PCV 127. During running, the vacuum pressure will keep super-heated vapour moving within the system as it absorbs room temperature heat. The cycle repeats through to the liquid tank 117 and then through the expansion valve 121 in the lcwer part 105 of the cooling container 131 where latent heat of fusion takes place.

The heat exchanger 111 can be of any known type.

As with the first embodiment, whilst a single cooling container 131 has been shown and described in Figure 5, in some embodiments further such containers can be used for similar purposes. For example, a second such container can be used as a back-up and/or for pressure equalisation.

It will be appreciated that the above described embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and ir.odifications will be apparent to persons skilled in the art upon reading the present application.

Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and/or combinaticn of such features.