AU2008202002A1

AU2008202002A1 - Air conditioning

Info

Publication number: AU2008202002A1
Application number: AU2008202002A
Authority: AU
Original assignee: Inform Energy Pty Ltd
Current assignee: Inform Energy Pty Ltd
Priority date: 2007-05-09
Filing date: 2008-05-06
Publication date: 2008-11-27

Description

Australian Patents Act 1990 Regulation 3.2 00

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ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Air conditioning The following statement is a full description of this invention, including the best method of performing it known to me/us:- P/00/011 5102 -1- 00 (Ni AIR CONDITIONING Background of the Invention The present invention relates to a method and apparatus for providing air conditioning and in particular for providing solar powered air conditioning.

Description of the Prior Art The reference in this specification to any prior publication (or information derived from it), 00 or to any matter which is known, is not, and should not be taken as an acknowledgment or I admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Air-conditioning apparatus can be used for cooling air within a space, such as within a building. Typical compressor based air conditioning systems utilise a lot of energy to operate, which in turn places a large load on electricity supply systems, and leads to large operating costs. This problem is particularly evident in large buildings and building complexes, such as office blocks or shopping centres, where cooling requirements are typically high, thereby requiring air conditioning equipment to operate almost continuously.

Absorption chillers are known systems that are able to heated water or steam as a. heat source to drive an evaporation based cooling cycle, to allow air or other fluids to be cooled.

However, such systems are generally of only a limited efficiency, making them unsuitable for use in most air conditioning applications.

Summary of the Present Invention It is an object of the present invention to substantially overcome, or at least ameliorate, one or more disadvantages of existing arrangements.

In a first broad form the present invention provides apparatus for providing air conditioning, the apparatus including: a) at least one solar collector for heating a heat transfer medium; b) a heat storage vessel for storing heat transfer medium; and, 00 i c) an absorption chiller for using heat from the heat transfer medium for providing air conditioning.

IND Typically the apparatus includes feed lines for interconnecting at least the solar collector and the heat storage vessel, and wherein, in use, the feed lines are at least one of: a) unpressurised; and, Sb) drained when the solar collector is not in use.

Typically the solar collector includes a heat tube for containing the heat transfer medium and 00 wherein, in use, the heat tube is at least one of: NI a) unpressurised; and, b) drained when the solar collector is not in use.

Typically the absorption chiller receives the heat transfer medium from the heat storage vessel.

Typically the absorption chiller is for cooling fluid, the cooled fluid being used to provide air conditioning.

Typically the apparatus includes a controller for controlling the apparatus to perform at least one of: a) selectively pumping heat transfer medium through the solar collector to thereby store heat in the heat storage vessel; and, b) selectively pumping heat transfer medium from the heat storage vessel to the absorption chiller.

Typically the apparatus includes a controller for controlling the apparatus to perform at least one of: a) pumping heat transfer medium through the solar collector to thereby heat the heat transfer medium; and, b) draining of feed lines and the solar collector when heating of the heat tran:sfer medium is complete.

Typically the apparatus includes a controller for at least one of: -3o00 ,I a) selectively activating a first pump for pumping heat transfer medium through the solar collector; b) selectively positioning the solar collector for use; and, IN c) controlling valves in feed lines.

Typically the apparatus includes a controller for at least one of: Sa) selectively activating a second pump for pumping heat transfer medium through the absorption chiller; and, 00 b) selectively activating the absorption chiller.

I Typically the apparatus includes: a) an enviromruent sensor for sensing environmental conditions; and, b) a heat transfer store sensor for determining at least one of: i) a temperature of the heat storage vessel; and, ii) a temperature of fluid in the heat storage vessel; and, c) a controller for controlling the apparatus at least partially in accordance with at least one of the determined temperature and determined environmental conditions.

Typically the apparatus includes a controller for: a) a space sensor for determining a space temperature; and, b) a controller for controlling the absorption chiller at least partially in accordance the determined space temperature.

Typically the absorption chiller includes: a) an evaporator which uses evaporation of a refrigerant to cool fluid received via an inlet, and provide chilled fluid via an outlet; b) an absorber for: i) receiving evaporated refrigerant from the evaporator; and, ii) causing the evaporated refrigerant to be absorbed by a refrigerant-depleted solution to form a solution; c) a chiller generator for: i) receiving the solution from the absorber; ii) evaporating refrigerant from the solution using an external heat source heat to create the refrigerant-depleted solution; and, -4- 00 iii) providing the refrigerant-depleted solution to the absorber; d) a condenser for: i) receiving evaporated refrigerant from the chiller generator; ii) condensing the evaporating refrigerant and generating waste heat; and, iii) providing the refrigerant to the evaporator.

Typically the at least one solar collector is mounted on a roof of a building containing the space to be cooled.

00 Typically the solar collector shades at least part of the roof from incident sunlight, to thereby N reduce solar heating effects within the space to be cooled.

Typically the at least one solar collector includes: a) a heat tube for containing the heat transfer medium; and, b) a reflector for reflecting solar radiation towards the heat tube.

Typically the reflector has a substantially parabolic cross sectional shape to define a focal axis, the heat tube being positioned substantially aligned with the focal axis.

Typically the solar collector includes a framework for supporting the heat tube relative to the reflector.

Typically the solar collector is moveably mounted to a support to thereby allow the solar collector to be moved between operative and inoperative positions.

Typically the apparatus includes: a) a drive system; and, b) a controller coupled to the drive system for selectively moving the solar collector between the operative and inoperative positions.

Typically the solar collector includes an impact protection layer provided on a reverse side of the reflector.

Typically, in an inoperative position, the impact protection layer is facing away from the roof.

00 Typically the heat storage vessel is for use in supplying hot water.

Typically the heat storage vessel includes a heat exchanger mounted in a fluid filled cavity, INO the heat exchanger being for receiving the heat transfer medium to thereby heat the fluid filled cavity.

Typically the heat exchanger is a coiled or convoluted feed line.

Typically the heat storage vessel is formed from at least one reverse acting calorifier.

00 STypically the apparatus includes a hot water control for controlling the supply heat transfer medium to the heat storage vessel.

Typically the absorption chiller is for at least one of: a) providing waste heat for heating a swimming pool; and, b) providing at least one of heated fluid and cooled fluid to an air conditioning system.

Typically the apparatus includes a heat exchanger for thermally coupling the absorption chiller to the swimming pool.

Typically the apparatus includes a pool control for selectively controlling flow rates through the heat exchanger.

Typically the apparatus includes air conditioning feed lines for supplying air conditioning fluid from the absorption chiller to the air conditioning system.

Typically the apparatus includes an air conditioning control for selectively controlling flow rates through the air conditioning feed lines.

Typically the air conditioning fluid is at least one of chilled or heated.

In a second broad form the present invention provides a method of providing air conditioning using apparatus including at least one solar collector for heating a heat transfer medium, a heat storage vessel for storing heat transfer medium and an absorption chiller for using heat from the heat storage medium to provide air conditioning, the method including, in a controller: -6- 00 a) selectively pumping heat transfer medium through the solar collector to thereby store heat in the heat storage vessel; and, b) selectively pumping heat transfer medium to an absorption chiller for use in providing air conditioning.

5 Typically the method includes selectively pumping heat transfer medium to the absorption chiller from the heat storage vessel.

Typically the method includes, in the controller: 00 a) pumping heat transfer medium through the solar collector to thereby heat the heat transfer medium; and, b) draining of feed lines and the solar collector when heating of the heat transfer medium is complete.

Typically the method includes, in the controller: a) selectively activating a first pump for pumping heat transfer medium through the solar collector; b) selectively positioning the solar collector for use; and, c) controlling valves in feed lines.

Typically the method includes, in the controller: a) selectively activating a second pump for pumping heat transfer medium through the absorption chiller; and, b) selectively activating the absorption chiller.

Typically the method includes, in the controller, at least partially controlling the apparatus at in accordance with signals from at least one of: a) an environment sensor for sensing environmental conditions; and, b) a heat transfer store sensor for determining at least one of: i) a temperature of the heat storage vessel; and, ii) a temperature of fluid in the heat storage vessel; and, c) a space sensor for determining a space temperature.

Typically the at least one solar collector is moveably mounted to a support to thereby allow the solar collector to be moved between operative and inoperative positions, and wherein the -7- 00 i method includes, in the controller selectively activating a drive system to thereby move the solar collector between the operative and inoperative positions.

IO Typically the method is for use with the apparatus of the first broad form of the invention.

In a third broad form the present invention provides apparatus for providing air conditioning using at least one solar collector for heating a heat transfer medium and a heat storage vessel for storing heat transfer medium and an absorption chiller for using heat from the heat oO transfer medium to provide air conditioning, the apparatus including a controller for: 00 a) selectively pumping heat transfer medium through the solar collector to thereby store ri heat in the heat storage vessel; and, b) selectively pumping heat transfer medium to an absorption chiller for use in providing air conditioning.

Typically the apparatus performs the method of the second broad form of the invention.

Brief Description of the Drawings An example of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a solar powered air conditioning system; Figures 2A and 2B are schematic side and plan views of the solar array of Figure 1; Figures 3A and 3B are schematic side views of a solar array in operative and inoperative positions respectively; Figure 4 is a schematic diagram of an example of an absorption chiller; Figure 5 is a schematic diagram of an example of a controller; and, Figure 6 is a flow chart of an example process for controlling the apparatus of Figure 1.

Figure 7 is a schematic diagram of a second example of a solar powered system; Figure 8 is a schematic diagram of an example of a heat storage vessel; and, Figure 9 is a flow chart of an example process for controlling the apparatus of Figure 7.

Detailed Description of the Preferred Embodiments An example of a solar powered air-conditioning apparatus will now be described with reference to Figures 1 and 2.

-8- 00 r In broad terms, the apparatus includes at least one solar collector 100 for heating a heat transfer medium, a heat storage vessel 110 for storing the heat transfer medium and an absorption chiller 120 for using heat from the heat transfer medium for providing air N conditioning.

In one example, the apparatus is used in a pressure less, drain back configuration. In this Sinstance, the heat transfer medium within the system is unpressurised, thereby avoiding the need for complex pressurisation systems, which can in turn renders the apparatus more 00 simple, reliable and cheaper to construct than existing alternatives. In this instance, the heat transfer medium is generally drained from at least the solar collectors when heating is no longer required, thereby avoiding the heat transfer medium from boiling, or the like, as can occur in a non-pressurised system.

Generally the solar collectors include a heat tube 101 for containing the heat transfer medium whilst this is exposed to solar radiation, thereby allowing the heat transfer medium to be heated. The heat transfer medium is then typically supplied to the heat storage vessel 110 and/or the absorption chiller 120 via one or more feed lines 111, 114, 116. Accordingly, in the pressure less, drain back, configuration, the heat tubes 101 and the feed lines 111, 114, 116 can be unpressurised and drained when not in use. This may be achieved in any one of a number of ways, as will now be described in more detail.

In one specific example, the apparatus includes the solar collectors 100 A, 100B (two shown for the purpose of illustration only), each having a respective heat tube 101A, 10lB. The heat tubes 101A, 101B are connected to each other via a second feed line 114, and to a heat storage vessel 110, by respective first and third feed lines 111, 116. This forms a fluid circuit allowing a heat transfer medium to be pumped from the heat storage vessel 110 through the first, second and third feed lines 111, 114, 116 and the heat tubes 101A, 101B, and returned to the heat storage vessel 110. This is generally achieved using a pump 112 provided in the first feed line 111, although any suitable arrangement may be used. This allows heat to be recovered from solar radiation and stored in the heat storage vessel.

The heat storage vessel 110 also includes an outlet feed line 117 having a pump 118 and an inlet feed line 119, coupled toan absorption chiller 120, having an inlet 121 for receiving air and an outlet 122 for providing cooled air to a space to be cooled. This arrangement allows -9o00 r heat from the heat storage vessel 110 to be used to drive the absorption chiller 120, which in turn uses this to provide cool air for use in conditioning air within a building space.

IDIn one example, a heat transfer medium such as a high temperature thermal oil is preferred as this generally has a high specific heat capacity and a high boiling point (relative to other 5 typical heat transfer mediums such as water). As a result, the thermal oil can be heated to a much higher temperature without risk of the oil boiling. The oil also stores a greater amount of heat for a given temperature change than other fluids such as water. This makes it 00 particularly useful in solar heat recovery, as it allows a large amount of heat to be recovered, without requiring pressurisation of the feed lines 111, 114, 116 and the heat tubes 101 to prevent boiling of the oil. To further ensure boiling does not occur, the solar collectors can be drained of any heat transfer medium when not in use.

Being able to avoid the need for pressurisation vastly reduces the complexity of the equipment and in turn allows cheaper materials to be used in construction, thereby reducing construction, installation and maintenance costs.

In the event that thermal oil is used as the heat transfer medium, the heat storage vessel 110 is generally formed from a fully (double) bunded unpressurised tank, to thereby ensure safe storage of the thermal oil. Fully bunded tanks include a double skin so that the heat storage vessel effectively includes an inner tank positioned within an outer tank.

The inner tank is used as the primary form of storage but if it is overfilled or leaks, a pollution incident is avoided because the liquid collects in the outer tank, from where it can be disposed of in a safe manner. Additionally, the double skin arrangement can be used to improve the thermal insulation properties of the heat storage vessel, improving the heat retention properties as will be appreciated by those skilled in the art.

The apparatus typically includes controller 130 for controlling the operation of any one or more of the pumps 112, 118, the absorption chiller 120, the solar collectors 100A, 100B, and any valves provided in the feed lines, as will be described in more detail below.

In order to achieve this, the controller 130 may be coupled to one or more sensors for sensing operating conditions. This can include, for example, an environment sensor 131 for determining information relating to one or more environmental attributes such as the levels of 00 incident solar radiation, levels of wind, the likelihood of hail, or the like. A heat storage vessel temperature sensor 132 may be provided for sensing the temperature of the heat storage vessel 110 and/or heat transfer medium contained therein. The controller 130 can also be coupled to a space temperature sensor 133, which is adapted to determine the temperature of the space to be cooled.

An example of the solar collectors shown in more detail in Figures 2A and 2B. In particular, as shown the solar collector 100 is generally formed from a reflective surface 200, with the 00 heat tube 101A, 101B being held in position relative to the reflective surface using a framework 201 or the like. The reflective surface may be formed from a variety cf materials, such as silvered glass, a mirror surface, electro-polished stainless steel, or the like, depending on the preferred implementation.

The reflective surface 200 is typically parabolic in cross-sectional shape to focus sunlight onto a focal axis, with the heat tubes 101A, 101B, being aligned with the focal axis to thereby maximise heating of the heat transfer medium provided therein.

The solar collector 100 may also include an impact protection layer 203 mounted on a reverse side of the reflective surface 200, to thereby prevent damage to the surface during adverse weather, such as hail storms or the like.

Each heat tube 101 is generally formed from an outer tube 210 and an inner tube 211 which contains the heat transfer medium, in use. A vacuum is provided between the inner and outer tubes 211, 210, to reduce heat losses from the heat transfer medium through convection and conduction processes.

The ratio of the surface area of the heat tubes 101 and of the reflective surface 200 can provide up to a 400:1 increase in solar energy collection, whilst heat loss from the heat tube 101 is reduced by the surrounding vacuum. As this can result in high temperatures within the heat tubes 101, it is preferable to use a fluid with a high boiling point, such as thermal oil, as will be described in more detail below.

In use, the solar collector 100 is typically mounted to a building roof, or the like, as shown in Figures 3A and 3B. In one example, this is achieved by mounting the solar collector 100 on a roof 300 using a support structure 301. The support structure 301 can be coupled to the -11- 00 oO C framework 201, or any other part of the solar reflector 100, depending on the preferred implementation. In one example, this is achieved using a pivotal mounting, shown generally at 302. This allows the solar collector to be moved between an operative position shown in N Figure 3A, and an inoperative position shown in Figure 3B.

In the operative position, the reflective surface 200 faces away from the roof 300, allowing the reflective surface 200 to be exposed to solar radiation. This, in turn, allows sunlight to be reflected from the reflective surface 200 onto the heat tube 101A, 101 B thereby heating the 00 fluid transfer medium provided therein.

r In contrast, in the inoperative position, the reflective surface 200 faces generally downwards towards the roof 300. As a result, the impact protection layer 203 faces upwards, thereby preventing the reflective surface 200 from being damaged by impacts from falling objects, such as hailstones, or the like. Thus by placing the solar collectors 100A, 10013 in the inoperative position when not in use, this prevents damage to the solar collector, and in particular the reflective surface 200, thereby increasing the solar collector's life span.

The impact protection layer may be formed from any suitable material depending on the preferred implementation, and the level of protection required. For example, in regions prone to large hailstones, then it is typical to provide a one inch (2.5 cm) thick layer of silvered foam insulation, which is relatively cheap and yet capable of absorbing hailstone impacts.

However, it will be appreciated that a greater or lesser degree of protection may be provided.

The support structure 301 may extend below the roof 300 and may be coupled to or additional to the buildings existing structure, to provide sufficient strength to retain the solar collectors in place. This may be required for two main reasons. Firstly, the solar collectors are generally heavy and may not therefore be capable of being supported by a buildings existing roof structure. Secondly, the solar collector can be subject to high lateral loads generated by the impact of wind on the collector, further increasing the load requirements for the support structure 301.

The problem of wind loading can however be reduced by using a design in which the cross sectional area and/or overall height of the solar collector is minimised in the: inoperative position. It will be appreciated that this could be achieved in a number of ways;, such as by -12- 00 N, suitable arrangement of the framework 201 and the position of the pivotal mounting 302.

This helps reduce the likelihood of wind damage by allowing the solar collector to be returned to the inoperative position in the event that high winds occur, which is; especially N important when the solar collector is mounted in an exposed area, such as on a building roof 300, or the like.

SA further feature of roof mounting the solar collectors 100 on the roof of the building containing the space to be cooled, is that the solar collectors will shade a significant portion 00 of the roof area 300 from the incident sunlight. This reduces the solar heating effect within the space, thereby further reducing the need for air conditioning within the space. It will therefore be appreciated that the use of roof mounted solar collectors can allow the currently described systems to be used in situations where an absorption chiller alone may not normally provide sufficient cooling to the space.

In addition to moving the solar collector between the inoperative and operative positions, it may also be possible to orientate the solar collector at intermediate positions, to maximise exposure of the reflective surface 201 to solar radiation, based on the current sun position.

Thus, for example, in the early morning and late afternoon, the sun will typically be situated near the horizon, in which case, the reflective surface may need to be directed towards the horizon (parallel to the roof 300) instead of upwards substantially perpendicular to the roof 300, as shown in Figure 3A.

It will therefore be appreciated from the above that the solar collector may be placed in any suitable orientation depending on the implementation and current operating conditions.

In general, movement of the solar collectors 100A, 100B between the inoperative and operative positions can be achieved using any suitable drive system, such as a motor 134A, 134B for each solar collector. Operation of the motors is generally controlled by controller 130, allowing the orientation of the solar collectors to be adjusted as required.

An example of an absorption chiller will now be described with reference to Figure 4.

In particular, the absorption chiller 120 includes an evaporator 431 having the inlet 121 and the outlet 122. The evaporator 431 is coupled to an absorber 434, via a pipe 435, which is in turn connected to a generator 436 via pipes 437A, 437B as shown.

-13- 00 ri A pipe 441, having an inlet 442 coupled to the feed line 117 and an outlet 443 coupled to the feed line 119, receives heat from the heat storage vessel, and transfers this to the generator 436. The generator 436 is connected to a condenser 434 via a pipe 439. The condenser 434 O typically generates waste heat as shown at 444 and is also coupled to the evaporator 431 via a pipe 445.

SThe system utilises a solution formed form a combination of a refrigerant and an absorber in order to provide heat transfer mechanisms, as will now be described. Typically the solution is 00 either a water/lithium bromide or an ammonia/water combination as will be appreciated by a person skilled in the art.

In use, the evaporator 431 operates to receive liquid refrigerant from the condenser 434, via the pipe 445. The refrigerant is provided into a low-pressure environment within the evaporator 431, and evaporates, thereby extracting heat from fluid supplied to the inlet 121, via an appropriate heat exchanger. The chilled fluid is then output via the outlet 122, whilst the evaporated refrigerant is transferred via the pipe 435 to the absorber 434, where it is absorbed by a refrigerant-depleted solution.

The solution is transferred via the pipe 437A to the generator 436, which operates to heat the solution using fluid in the pipe 441, thereby causing the refrigerant to be evaporated. The remaining refrigerant-depleted solution returns to the absorber 434 via the pipe 437B, whilst the vaporised refrigerant is transferred via the pipe 439 to the condenser 434. The vaporised refrigerant is allowed to condense with waste heat being output at 444 before being transferred via the pipe 445 to the evaporator 431, thereby allowing the cycle to be repeated.

Accordingly, the above described absorption chiller utilises heat retrieved from the heat storage vessel 110 to allow air, supplied at the inlet 121, to be chilled and provided via the outlet 122. This cool air can be supplied to a space, such as one or more rooms, allowing the rooms to be cooled, as will be appreciated by persons skilled in the art.

In general, such absorption chillers are designed to operate using heated water as the heat source for evaporating the refrigerant. However, in the current arrangement, high temperature thermal oil from the heat storage vessel 110 is used to drive the absorption chiller. Despite the fact that the oil has a higher temperature than a heated water source, this -14- 00 does not have a negative impact on the operation of most absorption chillers, and in many cases leads to an increased operating efficiency, thereby improving the operation of the absorption chiller for the purpose of providing air conditioning.

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As described above, the controller 130 can control the pump 112, to control the rate of flow of heat transfer medium through the solar collectors 100A, 100B. This allows the controller 130 to control the duration for which the heat transfer fluid is in the heat tubes 101A, 101B, which in turn can be used to control the amount of heat provided to the heat transfer medium.

00 Additionally, the feed lines 111, 114, 116, and the heat tubes 101A, 101B can be drained by I allowing the heat transfer medium to return to the heat storage vessel 110 when further heating is not required. As a result, the degree of heating provided to the heat storage vessel 110 can be controlled.

As this arrangement can be used to control the temperature of the heat transfer medium and the heat storage vessel 110, this can be used to ensure that the heat transfer medium does not undergo a phase change, such as boiling, thereby obviating the need for a pressurised system.

Thus, for example, if thermal oil is used as the heat transfer medium, a sufficiently high flow rate through the heat tubes 101A, 101B can be maintained to ensure the oil does not boil under atmospheric pressure, before being returned to the heat storage vessel 110.

It will be appreciated that as the temperature of heat storage vessel 110 increases, the temperature of fluid entering the first feed pipe 111 increases, thereby reducing the length of time required to heat the heat transfer fluid to a preferred operating temperature.

Accordingly, this may require that the flow rate is adjusted as the temperature of the heat storage vessel 110 increases. Alternatively, by selecting a sufficiently high initial flow rate, this may not be required. This may also depend on the available solar radiation levels, and consequent heating power attainable by the solar collectors 100.

Once a required temperature is reached, in the heat storage vessel 110, the heat transfer medium can be returned to the heat storage vessel 110, and the feed lines 111, 114, 116 and the heat tubes 101A, 101B drained, preventing any residual heat transfer fluid from being overheated which would cause a phase change, such as boiling of the thermal oil.

00 I Accordingly, it will be appreciated that the above described configuration allows the system to operate in a pressure less, drain back, manner in which the heat transfer medium is unpressurised within the feed lines 111, 114, 116, and the heat tubes 101A, 101B, and N drained from the feed lines 111, 114, 116, and the heat tubes 101A, 101B when heating is not required. Avoiding the need for a pressurised system, by controlling flow rates and using drain back to avoid boiling of the heat transfer medium, allows for the complexity of the Ssystem to be vastly reduced, thereby reducing system cost and increasing reliability.

00 As part of the feed line draining process, one or more of the feed lines 111, 114, 116 may be opened to the atmosphere, thereby allowing air flow into and out of the feed lines 111, 114, 116 and the heat tubes 101A, 10lB. This not only assists with draining and refilling, but also allows for expansion of air in the system caused by changes in temperature. This can be achieved in any one of a number of ways such as by using an appropriately configured pump, and/or by using valves positioned in the feed lines (not shown for clarity). It will be appreciated however that in the situation where thermal oil is used, it is preferable to ensure that the oil is drained from the feed lines 111, 114, 116 and the heat tubes 101A, 101B before these are opened to the atmosphere, thereby ensuring oil does no leak into the environment and cause contamination.

In addition to this, the controller 130 would also typically be adapted to control the orientation of the solar collectors 100, based on signals from the environment sensor 131.

This allows the solar collectors 100 to be orientated to maximise heat collection, as well as to be placed in the inoperative position either when inclement weather is likely, or when solar heating is not required. This helps maximise efficiency of the system, whilst reducing the likelihood of damage to the solar collectors 100 OA, 100B.

The controller 130 can also be adapted to activate the absorption chiller 120 arnd the pump 118 when cooling is required, in accordance with signals from the space temperature sensor 133.

It will be appreciated from the above that the controller 130 may be any form of suitable controller but typically includes some form of processing system as shown for example in Figure -16- 00 oO In this example the controller 130 includes a processor 500, a memory 501, and input/output device (I/O device) 502, such as input buttons, a key pad, display or the like, or an optional external interface 503. It will therefore be appreciated that the controller 130 may be in the ICform of a suitably programmed processing system, such as a computer, laptop, palm top, PDA, or alternatively may be specialised hardware, a programmable logic controller, field programmable gate array (FPGA) or the like.

In use, the controller 130 will execute a control protocol to allow the heat recovery system to 00 recover heat from the flue 101 as required. An example of the control protocol will now be described with reference to Figure 6.

At step 600 the controller 130 monitors the temperature of the heat storage vessel 110 utilising the heat storage vessel temperature sensor 132. At step 610 the controller 130 determines if heating is required. It will be appreciated that this may be achieved in any one of a number of ways. For example, this may involve comparing the current heat storage vessel temperature to a predetermined threshold representing the minimum heat storage vessel temperature required to operate the absorption chiller. Alternatively, this may involve comparing the current heat storage vessel temperature to a predetermined threshold representing the maximum heat storage vessel temperature.

In either case, it will be appreciated by persons skilled in the art that the threshold value would typically be stored in the memory 501 allowing the processor 500 to perform the comparison. Such thresholds can be stored in memory 501 in the form of an LUT (Look Up Table), or the like, as will be appreciated by those skilled in the art.

If it is determined that heating is required at 610 the controller 130 moves on to step 620 to determine if suitable conditions are present for performing heating using solar power. This may involve having the controller 130 determine signals from the environment sensor 131 to determine if environmental conditions are appropriate, for example, if there is sufficient light to allow heating of the heat transfer medium. Thus, if it is currently night time, the controller 130 will determine that heating cannot be achieved and hence that the solar collector should not be used.

-17- 00 oO It will be appreciated that other environmental conditions may also be examined, such as current wind velocity levels, the likelihood of hail or the like. This information may be obtained from the environmental sensor 131 and/or a remote computer system, such as a meteorological computer system, web-site, or other service. Thus, it will be appreciated that in one example the environmental sensor 131 could include a remote computer system adapted to provide meteorological or other environmental information.

If the current conditions are not suitable for performing solar collection, the controller 130 00 will simply wait until changed conditions occur and heating can be performed.

N Once it is determined that heating can be performed at step 630 the controller 130 activates the pump 111 and positions the solar arrays 100A, 100B to allow heating of the heat transfer medium.

A required flow rate and corresponding pump speed may also be determined from memory 501. This may be in the form of a fixed flow rate, which can therefore be predefined and stored for example in the memory 501. Alternatively, this may involve selecting a flow rate based on the current ambient light incident on the solar collectors, and the temperature of the heat storage vessel 110. It will be appreciated that the required flow rates will also typically depend on factors, such as the dimensions and in particular, the cross sectional area of the feed lines 111, 114, 116 and the heat tubes 101A, 101B, and would therefore typically need to be pre-stored in memory depending on the constructional design of the feed lines 111, 114, 116 and the heat tubes 101A, 101B.

The controller 130 will then continue to monitor the temperature of the heat storage vessel 110 at step 600 until the controller 130 determines that the heat storage vessel 110 no longer requires heating. This will occur for example if the temperature of the heat storage vessel 110 reaches a predetermined maximum threshold representing the maximum heat storage capability of the heat storage vessel 110.

At this stage, if it is determined that no further heating is required the controller 130 deactivates the pump 111 and drains the feed lines 111, 114, 116 as well as the heat tubes 101A, 10B. This is performed to remove any heat transfer medium from the apparatus, -18- 00 i thereby preventing boiling of the heat transfer medium, and avoiding the need for S pressurisation.

IND Separately to this, but performed simultaneously in parallel) with the above steps, the controller 130 will also control the operation of the absorption chiller 120 to provide the required cooling. In this instance at step 650, the controller 130 monitors the space temperature utilising the space temperature sensor 133. At step 660 it is determined if cooling is required and if this is not the case, the process will continue to monitor the space 00 temperature until cooling is required.

NI If cooling is required, at step 670 it is determined if sufficient thermal energy is stored in the heat storage vessel 110. Assuming this is the case, then at step 680 the controller 130 activates the pump 118 and the absorption chiller 120. This will cause heat transfer medium to be supplied to the absorption chiller 120, from the heat storage vessel 110, allowing the absorption chiller to operate as described above. This process is then continued until it is determined that no further cooling is required at step 660.

If at any stage during this process it is determined that insufficient thermal energy is stored in the heat transfer vessel 110 then an optional alternative backup cooling process may be used at step 690. This can include for example, operating the absorption chiller using an alternative heat source, heating the heat transfer medium using a different mechanism, or using alternative cooling methods such as a compressor based air conditioning sys;tem.

It will be appreciated that the need to perform this is extremely rare. In particular, cooling is generally required when the sun is exposing the building, thereby causing an increase in heat within the internal space. However, in this instance, sufficient sunlight is available to operate the absorption chiller 120, in which case, alternative heating is not required. In general, as long as sufficient solar collectors 100 are provided, then with appropriate configuration, cooling should only ever be required in the event that sunlight is incident on the building, in which case, the above described system can operate to provide sufficient cooling.

In the above example, two separate control processes are provided running in parallel, one to maintain the temperature of the heat storage vessel 110, using the solar collectors, and 19- 00

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N another to control the absorption chiller 120. However, this is for the purpose of illustration only, and is not intended to be limiting.

ND It will be appreciated that despite the fact that operation of an absorption chiller 120 is generally less efficient than the use of a compression based air conditioning systems, by having this arrangement operate using solar power, this reduces the need for electricity, thereby vastly reducing operating costs, and reducing the load on the electricity supply system. This in turn helps ensure that the existing infrastructure can be used to maintain 00 electricity supplies to a city or other locality, without risking overload to the system.

N Furthermore, by using a pressure less, drain back, configuration, this increases the reliability, whilst decreasing the cost of producing, installing, and maintaining the apparatus.

Whilst two solar collectors are shown in this example, this is for the purpose of illustration only and in practice any number of solar collectors may be used, depending for example on factors such as the space available to mount the solar collectors and the cooling requirements for the space.

An example of apparatus for providing domestic hot water, heating for a swimming pool and air conditioning for a domestic residence will now be described with reference to Figure 7.

In this example the apparatus includes a solar array shown generally at 700, having an array inlet feed line 701 and an array outlet feed line 702. The solar array would typically include a number of solar collectors similar to the solar collectors 100 described above with respect to Figures 1 to 3, and this arrangement will not therefore be described in further detail.

However, it will be appreciated that any suitable solar array may be used.

The array outlet feed line 702 is coupled to a first connector 710, which is in turn coupled to an absorption chiller 720, via a chiller inlet feed line 721, and to a hot water system 760, via a hot water system inlet feed line 761.

The absorption chiller 720 has a waste heat outlet feed line 723 and a waste heat return feed line 724, which are coupled to a heat exchanger 740. The heat exchanger 740 is in turn coupled to a swimming pool 730, via a pool inlet feed line 731 and a pool outlet feed line 732, thereby thermally coupling the waste heat generated by the absorption chiller 720, to the 00 swimming pool 730. In this example a pool temperature control 735 may be provided coupled to a control valve 736 provided in the waste heat outlet feed line 723. The absorption chiller 720 is also coupled to an air conditioning system 750 via an air IDconditioning inlet feed line 751 and an air conditioning return feed line 752. In this example the air conditioning system 750 includes an air conditioning control 755 coupled to a control valve 756.

As well as being coupled to the first connector, the hot water system 760 is coupled to a 00 second connector 770 via a hot water system return feed line 762. The hot water system 760 also includes a cold water inlet feed line 763 for receiving cold water and a hot water outlet feed line 764 for providing a supply of heated water. A hot water control 765 is provided coupled to a control valve 766.

The second connector 770 is coupled to the chiller return feed line 722 and the vessel return feed line 762 as well as to the array inlet feed line 701, to allow these feed lines to be selectively interconnected. The second connector is also coupled to a boiler 780 via a boiler inlet feed line 781, with the boiler being further connected to the first connector 710 via a boiler outlet feed line 782. A pump 771 may also be provided coupled to the second connector 770 to allow the pressure of the entire system to be controlled, or to provide a pumping force to urge thermal transfer medium through the solar array 700 at a desired rate.

Finally, a controller 790 is provided for controlling the operation of the apparatus. In one example, the controller 790 is coupled to the first and second connectors 710, 770, the solar array 700, the boiler 780, and control valves 791, 792 provided in the boiler inlet 781, and the array inlet feed line 701, as shown. Optionally, the controller 790 may also be coupled to the absorption chiller 720, the pool temperature control 735, the air conditioning control 755 and the hot water control 765.

In use, a heat transfer medium is supplied from the second connector 770 via the array inlet feed line 701 to the solar array 700. The heat transfer medium is heated using the solar array, in a manner similar to that described above with respect to the previous examples, with heated transfer medium being supplied to the first connector 710, via the outlet array 702. In the event that the solar array 700 is unable to provide adequate heating, this can be detected by the controller 790, which can cause at least some of the heat transfer medium to be -21

OO

00 eg transferred to the boiler 780 via the boiler inlet feed line 781, with heated transfer medium being supplied via the boiler outlet feed line 782.

IAny suitable heat transfer medium may be used, depending on the preferred implementation.

In one example, the heat transfer medium can be water. Whilst this only allows a reduced temperature to be reached in the heat transfer medium, compared to if thermal oil were used as described above with respect to Figures 1 to 6, this is generally less important as a high ,i temperature is not necessarily required in this configuration. Furthermore, this avoids any 00 potential pollution issues that may arise with leakage of the heat transfer medium, which is more important in a domestic environment, for which the system is suitable. However, thermal oil can be used, if a higher heat transfer medium temperature is desired.

In one example, the system operates in a pressurised configuration, with the heat transfer medium being held under pressure to prevent a phase change due to heating. However, this is not essential, and in one example, the system can operate in a pressure less, drain back configuration. In this example, heat transfer medium can be drained from the feed lines 701, 702, and the solar array 700, when heating is not required. The heat transfer medium can be stored in any suitable storage vessel. In one example, this is achieved by storing the heat transfer medium in a vessel that forms part of the hot water system 760, although a separate heat transfer medium storage vessel may be used.

Operation of the system in a pressure less drain back configuration is substantially as described above. Thus, the thermal transfer medium is pumped through the solar array at a sufficiently high rate to avoid boiling, with the thermal transfer media being drained from the solar array when heating is not required. The use of the pressure less drain back configuration avoids the need for a pressurised system, thereby reducing complexity of the apparatus, as previously described.

In use, the controller 790 controls the first connector 710 to allow the heated heat transfer medium to be supplied via the chiller inlet feed line 721 and the hot water system inlet feed line 761 to the absorption chiller 720 and the hot water system 760, as required. This provides heat energy to the absorption chiller 720 and the hot water system 760 allowing them to operate as required.

-22oO 00 ,i In one example, the absorption chiller 720 is similar to the absorption chiller shown in Figure 4. In this instance, the absorption chiller inlet feed line 721 is coupled to the inlet 442, with the chiller outlet feed line 722 being coupled to the outlet 443. The waste heat outlet feed Iline 723 and a waste heat return feed line 724 contain a heat transfer medium, such as water, which is heated using the waste heat 444, whilst the air conditioning inlet and return feed lines 751, 752 are coupled to the outlet 122 and inlet 121, respectively.

Accordingly, it will be appreciated that the heat transfer medium supplied via the chiller inlet 00 721 provides the heat necessary to drive the absorption chiller 720 with the exhausted heat transfer medium being returned via the chiller return feed line 722 to the second connector 770, for reheating.

The absorption chiller 720 can operate in a normal chilling mode, and cool fluid received at via the air conditioning return feed line 752, providing the chilled fluid to the air conditioning system 750, via the air conditioning inlet feed line 751. Thus, it will be appreciated that chilled fluid can be used to provide air conditioning.

Alternatively, the absorption chiller 720 can act in a heating mode, transferring the heat received from the heat transfer medium, directly to the fluid received via the air conditioning return feed line 752. Consequently, in this example, the air conditioning system provides heating, thereby allowing the air conditioning system 750 to operate in a heating or cooling mode.

It will be appreciated that the air conditioning system 750 typically includes a pipe network 757 extending through a domestic residence, with the air conditioning system 750 providing cooling by pumping an operational fluid received at the air conditioning inlet feed line 751, through the pipe network 757. However, any suitable mechanism for transferring heat to, or removing heat from a space can be used, and the example given is for the purpose of illustration only.

The degree of heating/cooling provided is controlled by the air conditioning control 755, which in turn controls the rate of fluid flow through the air conditioning inlet feed line 751, and hence the degree of heating/cooling provided. The home controller 755 can be of any suitable form, but in one example is a thermostat control. The air conditioning control 755 -23- 00 may also provide control signals to the absorption chiller 720, to control the operating mode of the chiller, although alternatively this may be performed by the controller 790, in accordance with signals received from the air conditioning control 755. Thus, for example, IN the controller 790 can determine from the air conditioning control 755 whether heating or cooling is required, and then operate the absorption chiller 720 accordingly.

SThe absorption chiller 720 also utilises any waste heat in order to provide heating to the swimming pool 730. In one example, this is achieved by heating a heat transfer medium 00 supplied in the waste heat return feed line 724, with heated heat transfer medium being 00 supplied via the waste heat outlet feed line 723. Heat contained therein is transferred to pool water in the pool outlet feed line 732, using the heat exchanger 740, with heated pool water being returned in the pool inlet feed line 724. In this example, flow of heat is; controlled using the flow control valve 736, which is in turn controlled using the pool control 735, which may be any suitable controller such as a thermostat or the like, allowing flow rates through the heat exchanger 740 to be controlled.

Similarly, the hot water system 760 receives heated heat transfer medium via the hot water system inlet feed line 761 and uses the heat contained therein to heat water received via the cold water inlet feed line 763, with heated water being supplied via the hot water outlet feed line 764. The cooled heat transfer medium is then returned via the hot water system return feed line 762 to the second connector 770, which in turn allows it to be repressurised utilising the pump 771 before being returned to the solar array 700, and/or the boiler 780, for reheating.

The temperature of the hot water storage system 760, and consequently degree of heating provided to the water, and hence the temperature of water in the hot water outlet 764 can be controlled using the flow control valve 766, which is in turn controlled using the hot water control 765. In use, this typically monitors the temperature of a fluid in the hot water system 760, and activates flow of the heat transfer medium via the hot water system inlet and return feed lines 761, 762 if the temperature falls below a threshold. Accordingly, it will be appreciated that the controller 765 may be any suitable controller such as a thermostat or the like, although again control can be provided by the controller 790.

-24- 00 i Whilst any form of hot water system may be used, in one example, this is achieved using a heat storage vessel such as a reverse acting calorifier. An example reverse acting calorifier is the Rotex SC500 heat exchanger or equivalent, which is also referred to as a "Rotex Sanicube T M an example of which is shown in Figure 8.

In this example, the heat storage vessel includes a housing 831, which contains a primary O water circuit 832, an optional electric heating element 833, and a hot water supply 834. In use, the housing 831 defines a cavity 835, which is typically filled with water to help retain 0 and distribute heat.

0O C, The primary water circuit can provide a source of heating to heat the water 835A, and is typically formed from a copper or metal feed line 832A, having an inlet 832B and outlet 832C to allow the feed line 832A to be interconnected with source of heat. Thus, in this example, the inlet 832B and outlet 832C are connected to the inlet and outlet feed lines 761, 762, respectively. The electric element 833 can provide additional heating of the water if required, and may for example include an Incalloy 800 element or equivalent. The hot water supply 834 is typically formed from a PE-X heat exchange feed line 834 having an inlet 834A and an outlet 834B, which are coupled to the cold water inlet feed line 763 and hot water outlet feed line 764, respectively.

The heat storage vessel 830 can also incorporate side connectors 836A, 836B which allows the water 835A to be recirculated. In this example, the side connectors 836A, 836B can therefore be used to connect to the inlet and outlet feed lines 761, 762, and this may be preferred to the use of the primary water circuit to provide heat to the heat storage vessel 830, as this provides a greater flexibility in flow rates, and the like.

Operation of the system will now be outlined in Figure 9.

In this example, at step 900, the controller 790 determines if heating of the heat transfer medium is required. This may be determined in any suitable manner, but typically is achieved by monitoring the one of the controls 735, 755, 765, to determine if the absorption chiller 720 or the hot water system 760, require heat. Thus, for example, if one of the thermostats indicates that heating and/or cooling is required for any one of the swimming 00 oO Spool 730, the air conditioning system 750 and the hot water system 760, then this is detected by the controller 790, which in turn causes the heat transfer medium to be heated.

If it is determined that heat is not required at step 910, the controller 790 will return to step 900 to continue to monitor until heating is required.

If heating is required at step 910, then at step 920, the controller 790 determines if the prevailing conditions are suitable for performing solar heating. It will be appreciated that this Sis similar to step 620 in the example of Figure 6. This is typically achieved in a similar 00 0manner to that described above, and may involve monitoring environmental conditions, or the like, and this will not therefore be described in any detail.

If conditions are not suitable, then at step 930, the controller 790 activates the boiler 790.

Otherwise, the solar array is activated at step 940, in a manner similar to that described above, with respect to step 630.

In either event, once the relevant heat source is activated, the controller 790 controls the first and second connectors 710, 770, and optionally the pump 771, allowing the heat transfer medium to be heated and supplied to the absorption chiller 720 and/or the hot water system 760, as required.

The absorption chiller 720 and/or hot water system 760 can then be controlled to provide home heating/cooling, pool heating and hot water, using the respective controls 755, 735, 765, as required.

It will therefore be appreciated that the above described system allows for domestic hot water to be provided, in addition to pool heating, and air conditioning. This can be achieved to a large extent using solar energy alone. Thus, for example, when there is a high degree of incident sunlight, and cooling is required, this can be achieved using the absorption chiller and solar heating of the heat transfer medium. Waste heat is then used for pool heating and hot water supply.

When the incident sunlight is lower, less cooling is required, and hence the absorption chiller requires less energy to operate. In the event that incident sunlight alone carmot provide sufficient energy, additional energy can be supplied using the boiler 780, which can be a high -26- 00 efficiency gas boiler, thereby maximising the efficiency of the system, even under non- C optimal sunlight conditions.

IDIt will be appreciated that features from the above described examples may be used in conjunction. Thus, for example, the heat transfer medium draining techniques described with respect to Figure 1 could be implemented in the system of Figure 7. Similarly, in the arrangement of Figure 7, heat can be supplied to the absorption chiller 720 from the hot water system 760, for example by recirculating water from the cavity 835, through the absorption 00 chiller 720.

Accordingly, the above described systems allow air conditioning to be provided using solar energy. This is achieved by storing solar energy using a heat transfer medium, with the heat transfer medium being used to power an absorption chiller, which can in turn operate to provide air conditioning.

In one example, the systems utilise a solar collector array in a pressure less, drain back, configuration. In this instance, the heat transfer medium within the solar collector heat tube, and optionally within any feed lines, is unpressurised, with the rate of flow of the heat transfer medium through the heat tube being used to prevent the heat transfer medium from undergoing a phase change such as boiling. When the solar collector is not in use, the heat transfer medium can be drained from the solar collector heat tube, and optionally from any feed lines, thereby preventing the heat transfer medium boiling, or the like.

This provides a system having a vastly reduced complexity, and hence a lower cost and higher reliability than existing pressurised systems.

Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art should be considered to fall within the spirit and scope that the invention broadly appearing before described.