WO2006110944A1 - Air conditioning and heat recovery - Google Patents

Abstract

Apparatus for conditioning air in a space. The apparatus includes a cooling system for cooling and thereby dehumidifying received air to form supply air. A heat recovery system is then used to recover waste heat from the cooling system and heat a fluid, which is in turn used for heating air supplied to the space. A heat storage system is also provided for storing heat from the heated fluid.

Description

AIR CONDITIONING

Background of the Invention

The present invention relates to a method and apparatus for providing air conditioning and in particular air conditioning that incurs reduced electricity usage. The present invention relates to a heat recovery system for recovering heat from an air conditioner and to an air conditioning system.

Description of the Prior Art

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that the prior art forms part of the common general knowledge.

An air-conditioning apparatus can be used for cooling air within a space, such as within a building. Additionally, by cooling the air to a suitable temperature, the air-conditioning apparatus can be used to dehumidify air. As a result, air conditioning systems are often used in swimming pool environments to maintain comfortable air conditions.

As such environments typically have a high degree of humidity, it is typically necessary to cool the air to below 18° C to thereby ensure a sufficient degree humidity reduction. However, the air must then be reheated before insertion into the space to ensure the pool, environment is not too cold. Providing such a degree of cooling and heating is an inefficient process and as a result, such air conditioning systems use a large amount of energy making running the air-conditioning apparatus expensive.

The infrastructure used to supply mains electricity is typically configured to ensure it is capable of meeting maximum expected demand levels. However, in many modern cities it is apparent that infrastructure is often operating virtually at maximum capacity. Consequently, high levels of demand coupled with even minor operating problems can lead to power outages, and in the event that there is high usage by all customers simultaneously, this is likely to over load the supply capabilities.

To reduce the chance of such an occurrence, most electricity supply companies utilise scaled tariffs in which electricity costs are scaled dependent on usage volumes, so that during peak usage times, which typically coincides with business hours, a greater rate is charged. This is intended to encourage improvements in efficiency to thereby reduce the likelihood of demand exceeding supply capabilities.

In addition to a scaled tariff, limits on usage may also be implemented. In this instance, if the limit is exceeded, peak surcharges are incurred, which can lead to the cost of electricity being over double the normal peak hour charge.

Such operation is important in ensuring that the peak usage is minimised to allow the infrastructure to cope with supply requirements. However, this can in turn be expensive for users, and does not guarantee that demand will not exceed supply parameters.

This problem is particularly evident in large buildings and building complexes, such as office blocks or shopping centres, where there is a high demand for electricity. This is further exacerbated in environments where there is also a need for air conditioning as compressor driven air conditioning systems typically make up the single greatest mains load within the building.

As a result of this, particularly during hot weather, the operation of air conditioning can lead to substantial electricity demand. Not only does this lead to peak surcharges for many office buildings and the like, but additionally, it can place an undue load on the electricity supply infrastructure. In some situations, this has even led to rationing the use of air conditioning where the existing infrastructure is unable to cope with demand.

Summary of the Present Invention

In a first broad form the present invention provides apparatus for conditioning air in a space, the apparatus including: a) a cooling system for cooling and thereby dehumidifying received air to form supply air; b) a heat recovery system for: i) recovering waste heat from the cooling system; and, ii) heating a fluid using the recovered waste heat; c) a heating coil for heating the supply air using the heated fluid; and, d) a heat storage system for storing heat from the heated fluid. Typically the cooling apparatus includes: a) a compressor for compressing a refrigerant; b) a condenser coil for allowing the compressed refrigerant to condense; and, c) an evaporation coil for allowing the condensed refrigerant to evaporate thereby cooling the received air.

Typically the apparatus includes: a) a return air inlet for receiving returned air from the space; b) an outside air inlet for receiving outside air from outside the space; and, c) an energy transfer module coupled to the return air and outside air, the received air being received from the energy transfer module.

Typically the apparatus includes: a) an exhaust outlet for emitting exhaust air; b) an exhaust fan for supplying the received air from the energy transfer module to the exhaust outlet via a condenser coil; c) a supply air outlet for supplying air to the space; and, d) a supply fan for supplying the received air from the energy transfer module to the supply air outlet via an evaporation coil.

Typically the heat recovery system includes: a) an inlet for receiving fluid; b) an outlet for supplying heated fluid; and, c) a heat exchanger coupled to the inlet and the outlet, the heat exchanger being in heat communication with the cooling system to thereby heat the fluid using waste heat from the cooling system.

Typically the fluid recirculates from the outlet, via the heating coil and the heat storage system, to the inlet.

Typically the heat storage system includes one or more heat storage vessels for heating a heat storage medium using the heated fluid.

Typically the heat storage vessels storage vessels are Rotex heat exchangers.

Typically the fluid is water. Typically the heat storage medium is at least one of: a) water; and, b) a phase change material.

Typically the apparatus is for dehumidifying a swimming pool environment, the heat storage system being used to heat the swimming pool.

In a second broad form the present invention provides a heat recovery system for use in air conditioning including a cooling system for cooling and thereby dehumidifying received air to form supply air, the heat recovery system including: a) a heat exchanger for: i) recovering waste heat from the cooling system; and, ii) heating a fluid using the recovered waste heat; b) a heating coil for heating the supply air using the heated fluid; and, c) a heat storage system for storing heat from the heated fluid.

Typically the cooling apparatus includes: a) a compressor for compressing a refrigerant; b) a condenser coil for allowing the compressed refrigerant to condense; and, c) an evaporation coil for allowing the condensed refrigerant to evaporate thereby cooling the received air.

Typically the cooling apparatus includes: a) a return air inlet for receiving returned air from the space; b) an outside air inlet for receiving outside air from outside the space; and, c) an energy transfer module coupled to the return air and outside air, the received air being received from the energy transfer module.

Typically the cooling apparatus includes: a) an exhaust outlet for emitting exhaust air; b) an exhaust fan for supplying the received air from the energy transfer module to the exhaust outlet via a condenser coil; c) a supply air outlet for supplying air to the space; and, d) a supply fan for supplying the received air from the energy transfer module to the supply air outlet via an evaporation coil. Typically the heat recovery system includes: a) an inlet for receiving fluid; b) an outlet for supplying heated fluid which recirculates from the outlet, via the heating coil and the heat storage system, to the inlet.

Typically the heat storage system includes one or more heat storage vessels for heating a heat storage medium using the heated fluid.

Typically the heat storage vessels are Rotex heat exchangers.

Typically the fluid is water.

Typically the heat storage medium is at least one of: a) water; and, b) a phase change material.

Typically the cooling apparatus is for dehumidifying a swimming pool environment, the heat storage system being used to heat the swimming pool.

In a third broad form the present invention provides apparatus for providing air conditioning to a building, the apparatus including: a) an absorption chiller for using an external heat source to provide chilled fluid for use in providing air conditioning; and, b) a control system, the control system being for: i) monitoring signals from at least one sensor; ii) comparing the signal to predetermined criteria; and, iii) activating the absorption chiller dependent on the results of the comparison.

Typically the control system is for activating the absorption chiller dependent on at least one of: a) the mains supply electricity provided to the building reaching a surcharge level; and, b) the level of demand on the mains supply infrastructure.

Typically the apparatus includes an electricity usage sensor, and wherein the control system is for: a) comparing signals from the electricity usage sensor to criteria representing the onset of an electricity surcharge; and, b) activating absorption chiller in response to a successful comparison.

Typically the apparatus includes a generator for generating electricity, at least some of the waste heat from the generator being used as the external heat source for the absorption chiller.

Typically the apparatus includes a waste heat recovery system to recover waste heat from the generator.

Typically the apparatus includes a solar collector for heating a fluid to thereby act as the external heat source for the absorption chiller.

Typically the control system is for activating the absorption chiller dependent on available solar energy.

Typically the control system includes: a) a controller; and, b) the at least one sensor.

Typically the control system includes a remote processing system for communicating with the controller.

Typically the remote processing system is operated by an electricity supply company to allow the supply company to at least one of: a) monitor the operation of the absorption chiller; and, b) activate the absorption chiller.

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, 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.

In a fourth broad form the present invention provides a method of providing air conditioning to a building using an absorption chiller configured to use an external heat source to provide chilled fluid for use in providing air conditioning, the method including: a) monitoring signals from at least one sensor; b) comparing the signal to predetermined criteria; and, c) activating the absorption chiller dependent on the results of the comparison.

Typically the method includes, activating the absorption chiller dependent on at least one of: a) the mains supply electricity provided to the building reaching a surcharge level; and, b) the level of demand on the mains supply infrastructure.

Typically the method includes activating a generator for generating electricity, at least some of the waste heat from the generator being used as the external heat source for the absorption chiller.

Typically the method is used with apparatus according to the first broad form of the invention.

In a fifth broad form the present invention provides a control system for use in providing air conditioning to a building using an absorption chiller configured to use an external heat source to provide chilled fluid, the control system being for: a) monitoring signals from at least one sensor; b) comparing the signal to predetermined criteria; and, c) activating the absorption chiller dependent on the results of the comparison. Typically the control system includes: a) a controller; and, b) the at least one sensor.

Typically the controller is formed from a suitably programmed processing system.

Typically the controller is for communicating with a remote processing system.

Typically the control system is for performing 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 plan view of an example of air conditioning apparatus including a heat recovery system;

Figure 2 is a schematic side view of air conditioning apparatus of Figure 1;

Figure 3 is a schematic diagram of the air conditioning apparatus of Figure 1 and a heat storage system;

Figure 4 is a schematic side view of an example of a heat exchanger;

Figure 5 is a schematic view of a number of interconnected heat exchangers;

Figure 6 is a schematic side view of an example of a heat storage element; and,

Figure 7 is a schematic plan view of an example of a heat exchanger incorporating a number of heat storage elements.

Figure 8 is a schematic diagram of an example of an absorption chiller;

Figure 9 is a schematic diagram of a first example of a cooling system;

Figure 10 is a schematic diagram of an example of the controller of Figure 9;

Figure 11 is a flow chart outlining the operation of the controller of Figure 10; Figure 12A is a schematic diagram of a second example of a cooling system; and,

Figure 12B is a schematic diagram of the solar collector system of Figure 12A.

Detailed Description of the Preferred Embodiments

An example of an air-conditioning apparatus incorporating a heat recovery system will now be described with reference to Figures 1 and 2. In particular, Figure 1 shows an air- conditioning system 10 having a housing 11 provided on a base 12. The air-conditioning system includes a return air inlet 1, a supply air outlet 2, which are coupled, via appropriate ducting, to the space being conditioned. An outside air inlet 3 and an exhaust outlet 4 are coupled via ducting, to the external environment.

An energy transfer module 5 is coupled to the return inlet 1 and the outside air inlet 3 to allow intermixing of the air streams. Positioned downstream of the energy module 5 is a supply fan 6, an exhaust fan 7 and a make-up air fan 8. Positioned downstream of the supply fan 6 is a compressor 14 coupled to an evaporation coil 16 and a condensation coil 17. An additional heating coil 15 is also provided in the supply air outlet.

In use, return air and outside air enters the air-conditioning unit 10, via appropriate ducting (not shown) and the return air and outside air inlets 1, 4 and enters the energy transfer module 5. The energy transfer module 5 includes a number of paper baffles over which outside air and return air flow thereby causing intermixing of the outside air and the return air. This reduces the humidity of the air compared to the returned air whilst reducing the temperature of the air compared to the outside air.

Air is drawn through the energy transfer module 5 by the supply air fan 6 or the exhaust fan

7.

Air drawn through by the supply air 6 passes over the evaporation coil 16 and the heating coil 15 into the supply air outlet 2. Conversely, air drawn through by the exhaust fan 7 passes over the condensation coil 17 and into the exhaust outlet 4. Additional make-up air can be drawn in from the outside air inlet 3, via the make up air fan 8, and pass over the condensation coil.

hi use, the compressor 14 operates to compress a refrigerant in the condensation coil 17. The refrigerant is heated by the compression process and air passing over the condensation coil 17 removes waste heat from the refrigerant, thereby allowing it to cool to ambient temperature and hence condense into a liquid. To achieve this sufficient and this is achieved by controlling the relative operating speeds of the exhaust fan 7 and the make up air fan 8.

hi any event, the refrigerant then flows into the evaporation coil 16, under a reduced pressure thereby allowing the refrigerant to evaporate. The evaporation process absorbs energy thereby cooling air drawn through the apparatus by the supply air fan 6. The cooling causes water in the air to condense on the evaporation coil 16, thereby reducing air humidity. The cooled air then passes over the heating coil 15 allowing it to be heated to a desired temperature, to form supply air which can then be injected into the space.

During this process, a large amount of waste heat is generated by the compressor 14 whilst it compresses the refrigerant. Accordingly, the compressor 14 includes a heat exchanger 20, shown in Figure 3, which is coupled via a pipe 21 to the heating coil 15 and via pipes 22, 23 to a heat storage system 24. A pump 25 is used to pump thermal transfer fluid, which in this example is water, through the heat exchanger 20, the pipes 21, 22, 23, the heating coil 15 and the heat storage system 24.

The heat storage system 24 may take any one of a number of forms, but in this example, is formed from a number of interconnected heat storage vessels 30 which will be described in more detail below.

The heat exchanger 20 is typically in the form of a heat exchange pipe which is in thermal communication with the compressor 14 and/or the condensation coil 17. As the water enters the heat exchanger 20, via the pipe 23, the fluid is heated by waste heat from the compressor 14 with heated fluid being output via the pipe 21.

In use, the heated fluid is supplied to the heating coil 15 allowing the waste heat from the compressor to reheat the supply air to a desired temperature. The fluid is then transferred to the heat storage system 24, via the pipe 22, allowing the remaining heat to be stored. The fluid is then returned to the heat exchanger 20 via the pipe 23, allowing it to be reheated.

The rate of flow of the fluid can be used to control the temperature to which the water is heated, thereby allowing the degree of heating provided by the heating coils 15, and hence the temperature of the supply air to be controlled. In the event that the temperature increase of the supply air is insufficient, additional heating can be provided by an additional heat source.

In this example, the heat storage system includes an inlet pipe 26 and an outlet pipe 27 which are also coupled to the heat storage vessels 30. The inlet pipe 26 is adapted to receive cool water, for example, from a swimming pool, and allow this water to be reheated by stored heat within the heat storage vessels 30, returning the warmed water to the pool via the outlet pipe 27. This allows additional waste heat to be recovered and used in providing heating to the swimming pool, thereby reducing associated heating costs.

In one example, the heat storage vessel is formed from a Rotex SC500 heat exchanger or equivalent, which is also referred to as a "Rotex Sanicube™", is shown in Figure 4.

In this example, the heat storage vessel is formed from a housing 31, which contains a primary water circuit 32, an optional electric heating element 33, and a hot water supply 34. In use, the housing 31 defines a cavity 35, which is typically filled with water 35A to help retain and distribute heat.

The primary water circuit can provide a source of heating to heat the water 35 A, and is typically formed from a copper or metal pipe 32A, having an inlet 32B and outlet 32C to allow the pipe 32A to be interconnected with sources of waste heat. The electric element 33 car provide additional heating of the water 35 A if required, and may for example include an Incalloy 800 element or equivalent. The hot water supply 34 is typically formed from a PE-X heat exchange pipe 34 having an inlet 34A and an outlet 34B.

The heat exchanger 30 can also incorporate side connectors 36A, 36B which allows the water 35 A to be recirculated. In one example this can be used to allow the heated water from the pipe 22 to be recirculated through the housing 31 to thereby store heat and heat water in the hot water supply 34.

The use of the side connectors allows a number of heat exchangers to be interconnected, in series, or in parallel, to allow additional heat storage capabilities to be provided. A first example of this will now be described with reference to Figure 5. this is further described in copending application number

In particular as shown in Figure 5, a number of Rotex™ (six shown for the purpose of example only) type heat storage vessels 30A, ... 30F are provided each having two side connectors 36A, 36B, and an inlet 34A and an outlet 34B, connected to a pipe 34 to provide a hot water supply, as shown. It will be appreciated that in this example, the heat storage vessels 30 are therefore similar to those shown in Figure 4, and will not therefore be described in any further detail. The pipe 22, from the heating coil 15, is coupled to the side connectors 36A of the heat storage vessels 30 with the side connectors 36B being connected to the return pipe 23. Additionally the water inlet pipe 26 is coupled to the inlets 34A, with the hot water outlet pipe 27 being coupled to the outlets 34B as shown.

In use, heated water in the pipe 22 is supplied to the heat storage vessels 30 via the side connectors 36 A, allowing the water to be recirculated through the cavity 35 and returned via the side connectors 36B and the pipe 23 to the heat exchanger 20 for further heating. This in turn water supplied via the inlet pipe 26 to be heated within the heat exchange pipe 34 and returned to the swimming pool, via the outlet pipe 27.

In the event that additional heating of the swimming pool water is required, additional heat can be supplied for example through the use of the primary water circuit, or an additional heating element. To avoid excess heating of the water returned to the heat exchanger 20, only selected heat storage vessels may be provided with additional heating.

Heated water from the pipe 22 is supplied to the side connectors 36 A, which are located substantially towards the top of the heat exchangers 30. As the water 35A cools, convection within the cavity 35 will cause the cooler water to move towards the bottom of the cavity 35, thereby allowing it to be extracted via the lower side connectors 36B, for reheating. It will therefore be appreciated that it is preferable for the side connectors 36 A to be used as inlets, with the side connectors 36B being used as outlets to help ensure maximal heating of water within the pipe 34.

hi this example, the heat storage vessels 30 are coupled to the heat recovery system 20 in parallel so that each of the heat storage vessels 30 will be provided with water directly, which helps ensure each heat exchanger 30 is provided with a similar degree of heating.

However, it is also possible for the heat exchangers to be connected in series, with for example, the side connector 36B of one heat storage vessel 30 being coupled to the side connector 36 of the next heat storage vessel 30. This may be desirable, for example, when there are restrictions on space for piping etc, as well as to alter the profile of heating of the pool water. Thus, for example, if additional heating of the pool water is required, this can be provided by the heat storage vessels closest to the pipe 22 and the outlet pipe 26. this allows the water passing through the heat storage vessels and into the pipe 23 to undergo additional cooling in downstream heat storage vessels 30.

In any event, this provides a mechanism to allow a number of heat exchangers to be interconnected to provide for additional heat storage capacity.

However, in addition to the connections described above, a further side connection 36C can be provided in each heat exchanger. In this instance, the side connections 36C are interconnected via a balance Iine37, to help ensure that the volume of water 35A in each heat exchanger 30 is substantially equal. This helps reduce the chance of any of the heat exchangers overflowing, or running out of water 35 A, should there be an uneven inflow or outflow of water through the side connectors 36A, 36B.

In this regard, it will be noted that the side connectors 36C are provided in the lower half of the housing of the heat exchangers 40. The height difference between the side connector 36C and the normal water level inside the heat exchanger ensures that there is sufficient pressure within the pipe 48 to allow water to flow into a heat exchanger which has a low water level.

In addition to utilising water 35A within the heat storage vessel to store heat, a phase change material can be used. In one example this is achieved using a phase change element shown in Figures 6 and 7. This is also described further in copending application PCT/AU2005/001403.

As shown, the element 41 includes a housing formed from a generally cylindrical tube 42, having two end caps 43, so as to define a cavity 44. In use, the cavity 44 is filled with a phase change material 45, typically leaving an air gap 44A at one end of the cavity 44, as shown.

hi use, a number of elements can be arranged internally within a heat exchanger 30 to provide improved heat storage capabilities, as shown for example in figure 7. hi particular, when the phase change material is heated to above its melting point, it retains the energy required to melt the material as latent heat, with this energy being subsequently released as the material cools and solidifies. Accordingly, the particular phase change material used within the element 41 can be selected based on the temperature at which the water is to be stored, so that the material will undergo a phase change at approximately the desired storage temperature.

Examples, of suitable phase change materials include hydrated salts, such as calcium chloride dihydrate, calcium chloride hexahydrate, sodium phosphate heptahydrate, sodium phosphate dodecahydrate, sodium acetate trihydrate, and magnesium nitrate hexahydrate, each of which have a respective melting point.

In Australia for example, regulations require that domestic hot water is stored at 62⁰C. Accordingly, a suitable phase change material would be one that undergoes a phase change at 58°C, such as sodium acetate trihydrate. In general, swimming pools have a lower temperature, and accordingly a different phase change material may be used.

It will be appreciated that materials of this form can store a large amount of energy as latent heat, and as a result tend to be able to store up to thirteen times more energy than water over a suitable operating range, thereby leading to a vast increase in heat storage capabilities for a device such as the Rotex Sanicube.

Another example of an improved air conditioning system will now be described. This example uses an absorption chiller, an example of which will now be described with reference to Figure 8.

hi particular, the absorption chiller 830 includes an evaporator 831 having an inlet 832 and an outlet 833. The evaporator 831 is coupled to an absorber 834, via a pipe 835, which is in turn connected to a generator 836 via pipes 837A, 837B as shown.

A pipe 841, having an inlet 842, and an outlet 843 receives heat from an appropriate heat source, as shown at 840, and transfers this to the generator 836. The generator 836 is connected to a condenser 838 via a pipe 839. The condenser 838 typically generates waste heat as shown at 844 and is also coupled to the evaporator 831 via a pipe 845.

The 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 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 831 operates to receive liquid refrigerant from the condenser 838, via the pipe 845. The refrigerant is provided into a low-pressure environment within the evaporator 831, and evaporates, thereby extracting heat from fluid supplied to the inlet 832, via an appropriate heat exchanger. The chilled fluid is then output via the outlet 833, whilst the evaporated refrigerant is transferred via the pipe 835 to the absorber 834, where it is absorbed by a refrigerant-depleted solution.

The solution is transferred via the pipe 837A to the generator 836, which operates to heat the solution using fluid in the pipe 841, thereby causing the refrigerant to be evaporated. The remaining refrigerant-depleted solution returns to the absorber 834 via the pipe 837B, whilst the vaporised refrigerant is transferred via the pipe 839 to the condenser 838. The vaporised refrigerant is allowed to condense with waste heat being output at 844 before being transferred via the pipe 845 to the evaporator 831, thereby allowing the cycle to be repeated.

Accordingly, the above described absorption chiller utilises heat provided generally at 840 to allow fluid, such as air, supplied at the inlet 832 to be chilled and provided via the outlet 833.

A first example of a system for providing air conditioning will now be described with reference to Figures 9 and 10.

In this example, a generator 900 is provided having a waste heat recovery system 901 for providing waste heat to the absorption chiller 830 as shown. The generator 900 typically includes a cooling system in the form of a radiator 907, which is coupled to the generator 900 via a cooling circuit 908. A controller 905 is provided coupled to the generator 900 and the absorption chiller 830.

In use, waste heat may be transferred from the generator 900 to the absorption chiller 830 in a number of manners. For example, this can be achieved by transferring hot exhaust gases to the absorption chiller 830 via the pipe 901. Alternatively, water or another suitable coolant fluid can be pumped through a heat exchanger incorporated into the generator 900 and then recirculated through the pipe 901. It will be appreciated that in one example this may be achieved by providing the pipe 901 as part of the cooling circuit 908.

In any event, this allows the waste heat from the generator 900 to be recovered to drive the absorption chiller 930. Accordingly in use the absorption chiller can be used to provide a supply of cold air, via the outlet 833, for use in air conditioning or the like. Simultaneously the generator 800 can operate to generate electricity for use in a building. Any excess heat created by the generator, which is not used by the absorption chiller 830, is dissipated by the radiator 907.

In use, operation of the generator 900 and the absorption chiller 830 is controlled using the controller 905, which operates to activate the generator 900 and the chiller 830 to reduce demand on the mains electricity supply. An example of the controller is shown in Figure 3.

In this example, the controller 905 includes a processor 1000, a memory 1001, an input/output device 1002 and an external interface 1003 interconnected via a bus 1004 as shown. In use the external interface 1003 is used to connect the controller to the generator 900 and absorption chiller 830, as well as to one or more sensors 1005.

The sensors 1005 are used to monitor various operating parameters of a buildings electricity usage, and optionally one or more other parameters, such as current outside temperature, operation of the generator 900 and absorption chiller 830, the current time, or the like, as will be described in more detail below.

In use, the controller 905 operates to monitor the operating parameters and control the generator 900 and the absorption chiller 830 accordingly. It will therefore be appreciated that the controller 905 may be in the form of a suitably programmed processing system, such as a computer, laptop, palm top, PDA, or alternatively may be specialised hardware, a programmable logic controller, or the like.

This can be achieved in any one of a number of ways depending on the preferred implementation.

An example of the control protocol will now be described with reference to Figure 11.

At step 1100 the controller 905 monitors signals from the sensors 1005, and compares these to predetermined criteria at step 1110. This is typically performed to determine when the electricity usage for the building is to exceed the tariff limit and peak surcharges are to be incurred. The comparison may be performed in any one of a number of ways, but typically involves the processor 1000 comparing the signals from the sensors 1005 to predetermined values stored in an LUT (Look Up Table) in the memory 1001. The LUT typically includes stored values indicative of the level of electricity usage that would incur a peak surcharge. Values indicative of other parameters may additionally or alternatively be used, as will be described in more detail below.

At step 1120, if it is determined that the criteria are not exceeded, the controller 905 leaves the generator 900 deactivated, allowing electricity to be obtained from the mains supply in the normal way. Otherwise at step 1130, the controller 905 activates the generator 900 and the absorption chiller 830, using the generator 900 to supply electricity to the building, with the absorption chiller being used to provide air conditioning.

Accordingly, the above-described system operates to monitor electricity usage in a building and automatically activate the generator 900 and chiller 830 in the event that a peak surcharge is to be incurred.

By generating electricity on-site, using the generator 900, this avoids the need to pay the surcharge, and reduces demand on the mains supply infrastructure. In general, the use of a generator / chiller combination would be ineffective as the generation of electricity on-site is . not as efficient as the use of mains supply. However, by using the waste heat from the generator 900, there is no electricity required to provide the air conditioning, and efficiency is consequently improved.

Even so, the absorption chiller 830 is generally less efficient than the use of a compression based air conditioning systems, and this arrangement is not suitable for use at all times. In particular, the cost of generating electricity using the generator 900 and operating the chiller 830 would typically exceed the cost of running a compression based air conditioner from mains electricity under normal charging rates.

However, by only using the generator/chiller arrangement when peak surcharges would be incurred, this minimises the need for maintenance and on-site fuel supplies, whilst allowing the provision of electricity and air conditioning, without incurring the surcharge. For larger buildings, such as office blocks or shopping centres, this can result in significant cost savings. In addition to this, the system vastly reduces demand on the mains supply infrastructure during critical peak hours, allowing the electricity supply to be used by other customers, such as home users. This in turn helps ensure that the existing infrastructure can be used to maintain electricity supplies to a city or other locality, without risking overload to the system. Furthermore, as implementing the above described system helps reduce peak load, this also allows existing infrastructure to be used for the foreseeable future, without requiring a large increase in capacity, even if the overall usage of the mains supply increases.

A further factor in implementing such systems is that most large buildings, typically have backup generators in place, which operate to provide electricity in the event that power supplies fail. These backup generators are typically only used to drive essential electricity services, but provide insufficient electricity to operate standard air conditioning equipment.

However, by utilising the waste heat from the generator, this allows the above described system to be retro-fitted to existing generator systems without incurring significant set-up costs.

As an example, a standard office block air conditioning system can require up to 600 Amps of electricity to operate, which in Australia equates to an operating cost of approximately A$1200 an hour during normal charge rates. However, during peak surcharge times, the cost can more than double, requiring A$2500 an hour.

Using a 26OkW generator operating on natural gas allows electricity to be supplied to operate building equipment. As this is not efficient as mains supply the cost of operating just the building equipment such as lighting, lifts, power supplies and the like would be about equal in cost to running the building and air conditioning from the mains at normal rates. As the chiller is effectively free to run, subject to maintenance costs, this means that the surcharge of

A$1300 per hour is saved using the above-described system, which over an entire year adds up to significant saving.

As will be appreciated by persons skilled in the art, current absorption chiller technology has only a limited efficiency, and accordingly, the process is generally only suitable for use when there is a space of at least 150 tons to be cooled, and hence when existing air conditioning uses approximately 40OkW of cooling power. However, this is not essential, and as more efficient technology is implemented, the system can be used in smaller buildings. Additionally, further operating efficiency improvements can be achieved using a solar based system as will now be described with reference to Figures 12 A and 12B.

In this example, the generator 900 is replaced (or alternatively supplemented) by a solar collector system shown generally at 1200. The solar collector system 1200 is formed from a pipe 1201 coupled to the inlet 842 of the absorption chiller 830, via a pump 1203. The pipe 1201 contains a fluid, such as water, steam, or the like, which is heated in the solar collector 1200, and supplied to the absorption chiller 830, before being returned via the outlet 843, for further reheating.

The solar collector is shown in cross section in Figure 12B. As shown a glass tube surrounds the pipe 1201, allowing the pipe to be contained within a vacuum 1212. A parabolic reflector

1210 is used to focus solar energy onto the pipe 1201 thereby providing heating of the fluid contained therein. The reflector 1210 is typically parabolic in cross-sectional shape, with the pipe 1201 being provided at a focal point to maximise the heating effect. The reflector 1210 may also be mounted on a suitable mounting to allow the position of the reflector 1210 to be adjusted to track the position of the sun, and again maximise heating effect.

The ratio of the surface area of the pipe 1201 and of the solar collector 1210 provides a 400:1 increase in solar energy collection, whilst heat loss from the pipe 1201 is reduced by the surrounding vacuum. Suitable pressurisation of the system allows fluid within the pipe 1201 to be heated to temperatures in excess of 440⁰C, thereby allowing the absorption chiller 830 to be operated as described above.

In this example, the controller 905 operates in a similar manner to that described above, additionally activating the pump 1203 to recirculate fluid within the pipe 1201.

In this example, operation of the system can be substantially as described above with respect to Figure 11. Thus, the pump 1203 and the chiller 830 can be activated at least when peak surcharges are to be incurred. As will be appreciated by persons skilled in the art, as the air conditioning within a building is the highest single load, peak surcharges typically only occur in hot weather when air conditioning is operating at maximum capacity. In this instance, there is usually sufficient sunlight available to operate the absorption chiller 830, and the system can therefore operate as described above. Additionally however, as the operation of the absorption chiller is substantially free in this instance, the system can be configured to operate whenever sufficient sunlight is available, and this can be determined using suitable sensors 1005, such as temperature, or light sensors, or the like. In this case, whenever the absorption chiller 830 is activated, this allows the normal air conditioning equipment to be shut down, or run at a reduced capacity, thereby further reducing costs.

It will also be appreciated that the above-described examples can be used in combination, with waste heat from a generator, and solar energy both being used to operate the absorption chiller through a suitable configuration.

In addition to activating the absorption chiller at least when peak surcharges are to be incurred, any one of number of other suitable parameters may be used.

For example, as the process can be used to reduce demand on mains supplies, the controller 905 can be configured to monitor current demand across a supply network to ensure that set demand limits are not exceeded. This can be achieved by linking the controller to the supply company systems using a suitable connection, such as via a communications network, the Internet, or the like. Thus, in this example, the process of Figure 11 is controlled by a control system formed from a remote processing system and the controller 905, with instructions from the remote processing system being supplied to the controller as required.

Thus, in one example, the remote processing system provides information regarding current usage, demand, billing levels or the like, with the controller 905 comparing this information to predetermined criteria, to thereby selectively activate the absorption chiller.

Alternatively, the supply company can monitor current demand, and activate the above described systems for one or more different buildings if required. This can be used even if peak load surcharges are not incurred, for example in the event that there is a short term increase in demand, a fault with the supply infrastructure which reduces supply capabilities or the like. This in turn enhances the capability of the supply company to maintain electricity supplies across a network, even in the face of adverse events, such as equipment failure.

Similarly, the control system can monitor the current time and activate the absorption chiller depending on the time of day. In this instance, this may be used for example, to control the operation of the system depending on electricity supply tariffs independent of surcharges to thereby minimise building operation costs. Additionally this may be required in the event that the electricity supply company places temporal restrictions on the use of standard air conditioning. In this latter case, the control system can be adapted to allow the operation of the absorption chiller to be monitored remotely by the supply company to ensure adherence to any such restrictions.

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.

For example, it will be appreciated that the two systems can be used in conjunction. Thus for example, the air conditioner with heat recovery can be used whilst tariff are below surcharge rates, with the absorption chiller configuration being used when peak surcharges would be incurred.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1) Apparatus for conditioning air in a space, the apparatus including: a) a cooling system for cooling and thereby dehumidifying received air to form supply air; b) a heat recovery system for: i) recovering waste heat from the cooling system; and, ii) heating a fluid using the recovered waste heat; c) a heating coil for heating the supply air using the heated fluid; and, d) a heat storage system for storing heat from the heated fluid. 2) Apparatus according to claim 1, wherein the cooling apparatus includes: a) a compressor for compressing a refrigerant; b) a condenser coil for allowing the compressed refrigerant to condense; and, c) an evaporation coil for allowing the condensed refrigerant to evaporate thereby cooling the received air. 3) Apparatus according to claim 3, wherein the apparatus includes: a) a return air inlet for receiving returned air from the space; b) an outside air inlet for receiving outside air from outside the space; and, c) an energy transfer module coupled to the return air and outside air, the received air being received from the energy transfer module. 4) Apparatus according to claim 3, wherein the apparatus includes: a) an exhaust outlet for emitting exhaust air; b) an exhaust fan for supplying the received air from the energy transfer module to the exhaust outlet via a condenser coil; c) a supply air outlet for supplying air to the space; and, d) a supply fan for supplying the received air from the energy transfer module to the supply air outlet via an evaporation coil. 5) Apparatus according to claim 1, wherein the heat recovery system includes: a) an inlet for receiving fluid; b) an outlet for supplying heated fluid; and, c) a heat exchanger coupled to the inlet and the outlet, the heat exchanger being in heat communication with the cooling system to thereby heat the fluid using waste heat from the cooling system. 6) Apparatus according to claim 3, wherein the fluid recirculates from the outlet, via the heating coil and the heat storage system, to the inlet.

7) Apparatus according to claim 3, wherein the heat storage system includes one or more heat storage vessels for heating a heat storage medium using the heated fluid. 8) Apparatus according to claim 3, wherein the heat storage vessels storage vessels are Rotex heat exchangers.

9) Apparatus according to claim 3, wherein the fluid is water.

10) Apparatus according to claim 3, wherein heat storage medium is at least one of: a) water; and, b) a phase change material.

11) Apparatus according to claim 3, wherein the apparatus is for dehumidifying a swimming pool environment, the heat storage system being used to heat the swimming pool.

12) A heat recovery system for use in air conditioning including a cooling system for cooling and thereby dehumidifying received air to form supply air, the heat recovery system including: a) a heat exchanger for: i) recovering waste heat from the cooling system; and, ii) heating a fluid using the recovered waste heat; b) a heating coil for heating the supply air using the heated fluid; and, c) a heat storage system for storing heat from the heated fluid.

13) A heat recovery system according to claim 12, wherein the cooling apparatus includes: a) a compressor for compressing a refrigerant; b) a condenser coil for allowing the compressed refrigerant to condense; and, c) an evaporation coil for allowing the condensed refrigerant to evaporate thereby cooling the received air.

14) A heat recovery system according to claim 13, wherein the cooling apparatus includes: a) a return air inlet for receiving returned air from the space; b) an outside air inlet for receiving outside air from outside the space; and, c) an energy transfer module coupled to the return air and outside air, the received air being received from the energy transfer module.

15) A heat recovery system according to claim 14, wherein the cooling apparatus includes: a) an exhaust outlet for emitting exhaust air; b) an exhaust fan for supplying the received air from the energy transfer module to the exhaust outlet via a condenser coil; c) a supply air outlet for supplying air to the space; and, d) a supply fan for supplying the received air from the energy transfer module to the supply air outlet via an evaporation coil.

16) A heat recovery system according to claim 12, wherein the heat recovery system includes: a) an inlet for receiving fluid; b) an outlet for supplying heated fluid which recirculates from the outlet, via the heating coil and the heat storage system, to the inlet. 17) A heat recovery system according to claim 12, wherein the heat storage system includes one or more heat storage vessels for heating a heat storage medium using the heated fluid.

18) A heat recovery system according to claim 12, wherein the heat storage vessels are Rotex heat exchangers.

19) A heat recovery system according to claim 12, wherein the fluid is water. 20) A heat recovery system according to claim 12, wherein heat storage medium is at least one of: a) water; and, b) a phase change material.

21) A heat recovery system according to claim 12, wherein the cooling apparatus is for dehumidifying a swimming pool environment, the heat storage system being used to heat the swimming pool.

22) Apparatus for providing air conditioning to a building, the apparatus including: a) an absorption chiller for using an external heat source to provide chilled fluid for use in providing air conditioning; and, b) a control system, the control system being for: i) monitoring signals from at least one sensor; ii) comparing the signal to predetermined criteria; and, iii) activating the absorption chiller dependent on the results of the comparison.

23) Apparatus according to claim 22, wherein the control system is for activating the absorption chiller dependent on at least one of: a) the mains supply electricity provided to the building reaching a surcharge level; and, b) the level of demand on the mains supply infrastructure. 24) Apparatus according to claim 22 wherein the apparatus includes an electricity usage sensor, and wherein the control system is for: a) comparing signals from the electricity usage sensor to criteria representing the onset of an electricity surcharge; and, b) activating absorption chiller in response to a successful comparison.

25) Apparatus according to claim 22, wherein the apparatus includes a generator for generating electricity, at least some of the waste heat from the generator being used as the external heat source for the absorption chiller.

26) Apparatus according to claim 25, wherein the apparatus includes a waste heat recovery system to recover waste heat from the generator.

27) Apparatus according to claim 22, wherein the apparatus includes a solar collector for heating a fluid to thereby act as the external heat source for the absorption chiller.

28) Apparatus according to claim 27, wherein the control system is for activating the absorption chiller dependent on available solar energy. 29) Apparatus according to claim 22, wherein the control system includes: a) a controller; and, b) the at least one sensor.

30) Apparatus according to claim 29, wherein the control system includes a remote processing system for communicating with the controller. 31) Apparatus according to claim 30, wherein the remote processing system is operated by an electricity supply company to allow the supply company to at least one of: a) monitor the operation of the absorption chiller; and, b) activate the absorption chiller.

32) Apparatus according to claim 22, wherein 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, 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.

33) A method of providing air conditioning to a building using an absorption chiller configured to use an external heat source to provide chilled fluid for use in providing air conditioning, the method including: a) monitoring signals from at least one sensor; b) comparing the signal to predetermined criteria; and, c) activating the absorption chiller dependent on the results of the comparison.

34) A method according to claim 33, wherein the method includes, activating the absorption chiller dependent on at least one of: a) the mains supply electricity provided to the building reaching a surcharge level; and, b) the level of demand on the mains supply infrastructure.

35) A method according to claim 33, wherein the method includes activating a generator for generating electricity, at least some of the waste heat from the generator being used as the external heat source for the absorption chiller.

36) A method according to claim 33, wherein the method is used with apparatus according to claim 22.

37) A control system for use in providing air conditioning to a building using an absorption chiller configured to use an external heat source to provide chilled fluid, the control system being for: a) monitoring signals from at least one sensor; b) comparing the signal to predetermined criteria; and, c) activating the absorption chiller dependent on the results of the comparison.

38) A control system according to claim 37, wherein the control system includes: a) a controller; and, b) the at least one sensor.

39) A control system according to claim 38, wherein the controller is formed from a suitably programmed processing system. 40) A control system according to claim 39, wherein the controller is for communicating with a remote processing system. 4I)A control system according to claim 38, wherein the control system is for performing the method of claim 33.