GB2621534A

GB2621534A - Thermoelectric system

Info

Publication number: GB2621534A
Application number: GB2206370.5A
Authority: GB
Inventors: Luke Yeates-Mayo William
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-04-30
Filing date: 2022-04-30
Publication date: 2024-02-21
Also published as: GB202206370D0

Abstract

An air conditioner having a thermoelectric device such as Peltier array 14 with heat sinks 24, a thermal store 80 and first and second heat exchangers 50, 52. In a heating mode, heat is transferred to a first fluid circuit from first side 13 of the thermoelectric element and transferred to first heat exchanger to heat the air passing through air passage 70 by first fan 60 to a local environment whilst fluid passing through a second fluid circuit is cooled by second side 15 of the thermoelectric element to the second heat exchanger which cools air passing through air passages 72 & 76 by second fan 62. In a cooling mode the thermoelectric device is reversed so that the first side provides cooling whilst the second side provides heating, reversing the heating and cooling performed by the heat exchangers. A third fluid circuit connects the second side of the thermoelectric device to the thermal store such as by a further thermoelectric device 115.

Description

THERMOELECTRIC SYSTEM

The present invention relates to a system for the control of air temperature of a local environment and the storage of thermal energy. In particular, the present invention relates to a domestic heating and cooling ventilation system having a thermoelectric heat pump and thermal store and preferably such a domestic heating and cooling ventilation system with an integrated thermoelectric heat pump.

BACKGROUND OF THE INVENTION

Air conditioning systems are increasingly being used to control the temperature of homes and businesses.

Currently, the domestic market is dominated by the use of vapor-compression refrigeration systems linked into ventilation systems. Such systems provide comfort heating and cooling through controlled air streams. Developments in this market are focussed on ever-improving mixtures of refrigerants within the system to improve system efficiencies, rather than focusing on refrigerant alternatives.

The increasing popularity of air conditioning is leading to an undesirable increase in the use of refrigerants such as CFCs. Unfortunately, this results in problematic leakage of refrigerants into the atmosphere with the consequential depletion of the ozone layer and associated contribution to global warming.

However, with the current desire to move away from the use of refrigerants and their detrimental environmental impact, there is a need for an alternative solution that less dependent on refrigerants, particularly in domestic environments.

Thermoelectric heat pumps, also known as Peltier devices, have been suggested as an alternative to conventional refrigerant-based air conditioning systems. Thermoelectric heat pumps (Peltier devices) are solid-state active heat pumps. When an electric current is driven through the device, heat is driven from one side of the device (the 'cold side') to the other side of the device (the 'hot side').

There are no moving parts, thereby reducing maintenance requirements and, more importantly, no use of refrigerants and therefore no associated environment impact.

However, there are downsides to thermoelectric heat pumps that have prevented their wide use in air conditioning systems. In particular, the coefficient of performance (COP) of thermoelectric devices is less than conventional refrigerant-based air conditioning systems.

There is therefore a need for an improved refrigerant-free air conditioning system with practical application in air conditioning systems.

SUMMARY OF THE INVENTION

The present invention seeks to address the problems of the prior art.

Aspects of the present invention are set out in the attached claims.

A first aspect of the present invention provides for the control of air temperature of a local environment and the storage of thermal energy, the system comprising: -a controller operable to receive a threshold temperature; -a sensor in electrical communication with the controller, the sensor being operable to measure the air temperature of the local environment and transmit a measured air temperature to the controller; -a first thermoelectric device in electrical communication with the controller, the first thermoelectric device comprising: a first plate and a second plate with an array of Peltier devices arranged therebetween; a first heat sink in thermal communication with the first plate; and a second heat sink in thermal communication with the second plate; -a heat exchanger unit in electrical communication with the controller, the heat exchanger unit comprising: a first heat exchanger in thermal communication with a first air passage, and a second heat exchanger in thermal communication with a second air passage, the first and second air passages in fluid communication with the local environment; and third and fourth air passages, each in fluid communication with an external environment, wherein at least the first and third air passages are in fluid communication with one another and at least the second and fourth air passages are in fluid communication with one another; -a first fan located at the first air passage and a second fan located at the second air passage; -a thermal store; -a first fluid circuit between the first plate and the first heat exchanger, a second fluid circuit between the first plate and the thermal store, and a third fluid circuit between the second plate and the second heat exchanger, wherein, on receipt of a measured air temperature by the controller that is less than the threshold air temperature, the controller is operable to supply power to the thermoelectric device to heat the first heat sink and cool the second heat sink, and to open the first and third fluid circuits and close the second fluid circuit, and to operate the first fan to expel heated air from the heat exchanger unit through the first air passage into the local environment,_ and to operate the second fan to extract cooled air away from the local environment through the second air passage towards the fourth air passage; and wherein, when the measured air temperature received by the controller reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device, close the first and third fluid circuits and open the second fluid circuit.

Thus, the thermoelectric device is activated when the measured temperature falls below a threshold air temperature. Heat generated at the first plate of the thermoelectric device is harvested and conducted to the heat exchanger unit where it is used to heat air which is supplied to the local environment. However, in addition to this, once the measured temperature of the local environment is reached, although the power to the thermoelectric device is reduced, heat will continue to be generated at the first plate. However, heat harvested at the first plate is no longer conducted to the heat exchanger and onward to the local environment. Instead, the harvested heat is conducted to a thermal store which may be used, for example, to provide heated water for use by a user. Thus, the measured air temperature of the local environment will not continue to rise, and no heat generated by the thermoelectric device is wasted. Additional sensors in the thermal store monitor the temperature of the water being heated, thereby providing a means of controlled heating of a hot water supply for the user.

Whilst this is achieved, thermal transfer occurs between the second plate and the second heat exchanger via the third fluid circuit where it cools air which is then exhausted to the external environment. This ensures that the reduced temperatures at the second plate do not impact the heating of the local environment whilst the measured air temperature is below the threshold air temperature.

In a first embodiment, on receipt of a measured air temperature by the controller that is greater than a threshold air temperature" the controller is operable to supply power to the thermoelectric device to heat the second heat sink and cool the first heat sink, and to open the first and third fluid circuits and close the second fluid circuit; and to operate the first fan to expel cooled air from the heat exchanger unit through the first air passage into the local environment, and to operate the second fan to extract air away from the local environment through the second air passage towards the fourth air passage; and when the measured air temperature reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device and stop the operation of the first and second fans.

Thus, when the measured air temperature rises above a threshold air temperature, the same system is able to control the operation of the fluid circuits to prevent further heated air being supplied to the local environment, and cooled temperatures at the second plate are conducted to the heat exchanger unit and used to cool air which is supplied to the local environment. At the same time, heat generated at the first plate is diverted to the thermal store to ensure that increased temperatures at the first plate do not impact the cooling of the local environment whilst the measured air temperature is above the threshold air temperature.

A second aspect of the present invention provides a system for the control of air temperature of a local environment and the storage of thermal energy, the system comprising: -a controller operable to receive a threshold temperature; -a sensor in electrical communication with the controller, the sensor being operable to measure the air temperature of the local environment and transmit a measured air temperature to the controller; -a first thermoelectric device in electrical communication with the controller, the thermoelectric device comprising a first plate and a second plate with an array of Peltier devices arranged therebetween, and a first heat sink in thermal communication with the first plate and a second heat sink in thermal communication with the second plate; -a heat exchanger unit in electrical communication with the controller, the heat exchanger unit comprising: a first heat exchanger in thermal communication with a first air passage, and a second heat exchanger in thermal communication with a second air passage, the first and second air passages in fluid communication with the local environment; and third and fourth air passages, each in fluid communication with an external environment, wherein at least the first and third air passages are in fluid communication with one another and at least the second and fourth air passages are in fluid communication with one another; - a first fan located at the first air passage and a second fan located at the second air passage; -a thermal store; - a first fluid circuit between the first plate and the first heat exchanger, a second fluid circuit between the first plate and the thermal store, and a third fluid circuit between the second plate and the second heat exchanger, wherein, on receipt of a measured air temperature by the controller that is greater than the threshold air temperature, the controller is operable to supply power to the thermoelectric device to heat the second heat sink and cool the first heat sink, and to open the first and third fluid circuits and close the second fluid circuit, and to operate the first fan to expel air from the heat exchanger unit through the first air passage into the local environment, and to operate the second fan to extract air away from the local environment through the second air passage towards the fourth air passage; and when the measured air temperature reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device and stop the operation of the first and second fans.

In one embodiment, on receipt of a measured air temperature by the controller that is less than the threshold air temperature, the controller is operable to supply power to the first thermoelectric device to heat the first heat sink and cool the second heat sink, and to open the first and third fluid circuits and close the second fluid circuit, and to operate the first fan to expel heated air from the heat exchanger unit through the first air passage into the local environmenti and to operate the second fan to extract cooled air away from the local environment through the second air passage towards the fourth air passage; and wherein, when the measured air temperature received by the controller reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device, close the first and third fluid circuits and open the second fluid circuit.

In this way, heated air is supplied to the local environment to increase the measured air temperature of the local environment until the threshold air temperature is reached.

The system may further comprise a user interface operable by a user to manually select the threshold air temperature. The selected threshold air temperature may be input in real time or programmed into the controller so that the system may operate independently of constant user input when a new threshold air temperature is desired. The threshold air temperature may be a specific air temperature or may alternatively track a selected number of degrees above or below the air temperature of the external environment. This will prevent excessive demands on the system in conditions of extreme external environmental air temperatures, for example during a very cold winter or at the height of a very hot summer. In addition, the threshold air temperature may be programmed to alter over time, for example, a lower threshold temperature may be selected during the hours of sleep to provide a more comfortable temperature conducive to healthy sleep patterns. Daytime threshold temperatures may be selected in dependence upon the use of the local environment by a user during all or part of each day. Such programming of air temperature requirements is known and can be applied to and operated by the system of the present invention.

In one embodiment, a plurality of thermally conductive pipes extend from respective first and second plates of respective first and second thermo-electric devices at least partially through the respective first and second heat sinks of respective first and second thermo-electric devices. This facilitates the displacement of the cool and heat temperatures from the respective cooling and heating plates.

In one embodiment, the array of Peltier devices of each respective thermoelectric device is mounted within a heat shield which is located between the first and second plates of respective thermo-electric devices. The presence of the heat shield helps to prevent transfer of cool and heat temperatures between respective cooling and heating plates.

In a further embodiment, a vapour chamber is provided between the heat shield and the respective first and second plates. The vapour chamber facilitates more even spreading of temperatures, thereby facilitating more efficient temperature exchange between the pipes and the respective first and second heat sinks.

Each of the respective first and second heat sinks may comprise a plurality of aligned correspondingly-shaped thermally conductive fins. It is to be appreciated that any suitably shaped conductive fins may be used provided they can be aligned and are fit for function.

It is to be appreciated that the system may be powered via mains power, or may preferably be operated via renewal energy sources such as, but not limited to, solar power, wind power, wave power, bioreactor-generated power, and the like. Where the system is installed in a domestic dwelling, the system may be connected to a solar panel associated with the domestic dwelling and powered using such a renewable energy source. This provides a reliable source of power for the system whilst ensuring reduced carbon emissions.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying figures in which: Figure 1 is a perspective view of a cross-section through a portion of a thermoelectric device of a system in accordance with a first embodiment of the present invention; Figure 2 is a perspective view of the thermoelectric device of figure 1 showing the array of Peltier units and respective heat sinks; Figure 3 is a perspective view of the thermoelectric device of figure 1 in fluid connection with at least a portion of first and second heat sinks; Figure 4 is a perspective view of a first embodiment of a system in accordance with the present invention, showing a thermoelectric device in fluid communication with a thermal store; Figure 5 is a cross-section through the embodiment of figure 4 showing two thermoelectric devices, one in fluid communication with the thermal store and one in fluid communication with respective first and second heat sinks; Figure 6 illustrates an embodiment of a system in accordance with the present invention in Heating Mode; Figure 7A illustrates the embodiment of figure 6 in Cooling Mode; and Figure 7B illustrates the embodiment of figure 7A in Cooling Mode when further cooling is required.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The thermoelectric device 12 will now be described with reference to the accompanying figures.

Figures 1 to 3 show portions of a thermoelectric device 12 comprising an array of 18 Peltier units 14 aligned in three columns of six units.

The array 14 is aligned such that on supply of electrical charge to the array 14, the Peltier units will activate to cause thermo-elements located on a first surface 13 of the array to give of a heating effect at the first surface 13 and the thermo-elements located on a second opposing surface 15 of the array to give off a cooling effect at the second surface 15.

The array of Peltier units 14 is mounted within a substantially planar heat shield 16. A substantially planar first plate 18 is located adjacent a first side of the heat shield 16 and a substantially planar second plate 20 is located adjacent a second opposing side 21 of the heat shield 16.

Heat shield 16 helps to minimise cross transfer of cool and or heat between the first and second plates 18, 20 when power is passed through the array of Peltier units 14, thus increasing the efficiency of the system 10.

A vapour chamber 22 is provided between each heat shield 16 and respective first and second plates 18, 20. A plurality of heat pipes 23 extend from respective first and second plates 18,20 and through respective heat sinks 24, 24'. Heat pipes 23 displace the heat/cool temperatures from respective first and second plates 18, 20 to respective adjacent heat sinks 24, 24', where they are thermally conducted through the system via various fluid pathways (discussed below). In the embodiment shown in the figures, heat sinks 24 comprise a plurality of aligned fins.

Vapour chamber 22 allows the hot or cool temperatures at the first and second surfaces to be spread more evenly. This provides more efficient heat transfer to the respective heat pipes 23.

The assembled system 10 incorporating the thermoelectric devices 12 and the operation of system 111 in a Heating Mode and then in a Cooling Mode will now be discussed with reference to figures 4 to 7.

System 111 comprises a single unit with an integrated thermal store 80. A first thermoelectric device 12 is in thermal communication with heat exchanger 54 which is in direct communication with fresh air inlet 74 and exhaust air outlet 76. A second thermoelectric device 112 is located adjacent thermal store 80.

During operation of the system 111, sensor 102 monitors the air temperature of the local environment (the 'measured air temperature') and transmits a signal to the controller 100 corresponding to the measured air temperature.

Manual control of the system 111 is via a user interface (not shown). A user sets a desired air temperature, the threshold temperature, for the local environment via the user. The desired air temperature is transmitted from the user interface to the controller 100.

On receipt of the desired air temperature, the controller 100 compares the desired air temperature with the measured air temperature and, if the desired air temperature is higher than the measured air temperature, heating mode is initiated. Alternatively, if the desired air temperature is lower than the measured air temperature, cooling mode is initiated.

Heating Mode Figure 6 shows the system 111 in Heating Mode.

Electrical charge is provided to the array 14 of Peltier units of thermoelectric device 12. The level of electrical charge provided to the array 18 is based on the desired temperature i.e. the threshold temperature. The level of electrical charge provided may be based on the user's required temperature set point or could be based on the degree of deviation of the desired set point from the measured air temperature. The user may be present within the local environment and manually enter required temperature changes via the user interface or the system may be programmed to maintain a desired comfort level, which may remain constant or may vary over a predetermined time-period, for example, over a daily cycle (taking into account changed requirements overnight) or over a weekly cycle (taking into account changed requirements over a weekend) etc. The electrical charge activates the Peltier units in the array 14, inducing the thermo-elements N on first surface 13 of array 14 to emit a heating effect and the thermo-elements P on second surface 15 of array 14 to emit a cooling effect. Temperature changes at the first and second surfaces 13 and 15 are detected by temperature sensors (not shown) and pumps 30, 30' are engaged to pump fluid through respective heat sinks 24, 24' and circulate the fluid through selected fluid pathways as described below.

Fluid flowing through heat sink 24 harvests heat generated at first surface 13 of array 14. This heated liquid passes from heat sink 24 through open energised valve 40 via fluid pathway I to heat exchanger 50 in air passage 70. After passing through heat exchanger 50, fluid is returned to heat sink 24 via open energised valve 42.

Air flow through fan 60 is increased to draw air past heat exchanger 50 and deliver heated air through air passage 70 into the local environment, thereby gradually raising the local air temperature.

In addition, during the Heating Mode, fluid flowing through heat sink 24' is cooled at a second surface 15 of array 14. This cooled fluid passes from heat sink 24' through energised valve 44 to heat exchanger 52 via fluid pathway III. After passing through heat exchanger 52, fluid is returned to heat sink 24' via open energised valve 46.

Air flow through fan 62 is increased to supply air through air passage 72 through heat exchanger 52 towards heat exchanger 54. The cooled air is then vented externally though air passage 76. After passing heat exchanger 52, circulating fluid is returned to heat sink 24' via open energised valve 46 via fluid pathway III.

The removal of cool temperature from second surface 15 of array 14 helps to remove any heat that has transferred across the array 14 from the first surface 13 to the second surface 15.

The direction of movement of air through air passages 70, 72, 74 and 76 during Heating Mode is shown in figure 6.

Sensor 102 continues to monitor the local air temperature and transmit a measured air temperature to the controller 100, and the system continues to operate in Heating Mode until the measured air temperature rises to the desired air temperature.

Once the measured air temperature has risen to the desired air temperature, electrical charge to the array 14 of Peltier units is slow reduced. However, heat continues to be absorbed across heat sinks 24 and 24'. Therefore, to prevent further heat being provided to the local environment, valve 40 closes fluid pathway I and opens fluid pathway II, diverting fluid from heat sink 24 to thermal store 80.

In addition, valve 44 operates to close fluid pathway III and divert fluid from heat sink 24 through fluid pathway II to thermal store 80 to heat water for a hot water supply. This ensures that no heat is wasted and provides a means of supplying heated water.

It is to be noted that valves 94 and 96 remain closed to fluid pathway III until the measured air temperature has risen to the desired air temperature. Once this stage is reached, valves 94, 96 close to fluid pathway IV and redirect circulating fluid into fluid pathway VII in thermal store 80.

When the controller 100 compares the desired air temperature with the measured air temperature and the desired air temperature is lower than the measured air temperature, there is a cooling requirement. A temperature sensor located in air passage 74 measures the temperature of the air being drawn in from the external environment. If the external environment air temperature is lower than the measured air temperature of the local environment (as measured by sensor 102), then air flow through fan 60 is increased to draw more air from the external environment through air passage 74 past heat exchanger 50 and into the local environment through air passage 70. However, if this is insufficient to meet the cooling requirement, then controller 100 initiates Cooling Mode.

Cooling Mode Figures 7A and 7B show the system 111 in Cooling Mode.

On initiation of Cooling Mode, electrical charge is provided to the array 18 of Peltier units. The level of electrical charge provided to the array 18 is based on the desired temperature. It is to be appreciated that the flow direction of the current is reversed with respect to the Heating Mode.

The electrical charge activates the Peltier units in the array 14, inducing the thermo-elements on first surface 13 of array 14 to emit a cooling effect and the thermo-elements on second surface 15 of array 14 to emit a heating effect.

Temperature changes at the first and second surfaces 13 and 15 are detected by temperature sensors (not shown) and pumps 30, 30 are engaged to pump fluid through respective heat sinks 24, 24' and circulate the fluid through selected fluid pathways as described below.

Valve 44 opens fluid pathway III, allowing heated fluid to flow from heat sink 24' towards heat exchanger 52 in air passage 72. Air flow through fan 62 is increased to draw air past heat exchanger 52 and deliver heated air through air passage 76 where it is subsequently vented into the external environment as exhaust air, thereby removing heat from the system 111 (see air pathway B in heat exchanger 54).

After passing heat exchanger 52, cooled fluid is returned to heat sink 24' via fluid pathway III and open valve 46 ready to remove heat again from heat sink 24' and recirculated it back to heat exchanger 52 for venting through passageway 76 to the external environment thus providing continuous cooling of the local environment.

Also, during Cooling Mode, fluid flowing through heat sink 24 is cooled at the first surface 13 of array 14 and the cooled fluid is circulated via fluid pathway I to heat exchanger 50 in air passage 70. Air flow through fan 60 is increased to draw supply air from the external environment through air passage 74 towards heat exchanger 50 (see air flow pathway A). Supply air is drawn past heat exchanger 50 where the air is cooled before exiting air passage 70 into the local environment, thereby providing a cooling effect. After passing through heat exchanger 50, fluid is returned to heat sink 24 via fluid pathway I, where it repeats the cycle of cooling at heat sink 24 and recirculating via fluid pathway I to heat exchanger 50. This process continues until the measured air temperature has been reduced to the desired air temperature. Once the measured air temperature has fallen to the desired air temperature, electrical charge to the array 14 of Pelter units of first thermo-electric device 12 is slow reduced. However, heat continues to be absorbed across heat sinks 24 and 24'.

Therefore, to prevent further cooling of the local environment, valves 40 and 42 close, thereby retaining cooled fluid in the upper half of fluid pathway I. During cooling mode, valves 94, 96 remain closed to fluid pathway Ill and open to fluid pathway IV.

During Cooling Mode, if additional cooling is desired, controller 100 will initiate power supply to second thermoelectric device 112. Operation of second thermo-electric device 112 results in a heating effect at first surface 113 and a cooling effect at second surface 115 (see figure 7B).

Valves 44 and 46 will close fluid pathway Ill thereby preventing heated fluid flow between heat sink 24' and heat exchanger 52. Valves 90 and 92 are opened to allow cooled fluid from heat sink 124' to flow into fluid pathway Ill and mix with heated fluid in the lower portion of fluid pathway Ill. This will require an additional pump (not shown) . The cooled mixed fluid is then provided to heat exchanger 52 as described above. This has the effect of reducing the heat provided to heat exchanger 54 via heat exchanger 52, resulting in less heating of incoming supply air from passageway 74 and the provision of lower temperature air to passageway 70 for further cooling at heat exchanger 50 before supply to local environment.

Heat produced at first surface 124 enters fluid pathway VII in thermal store 80 and is used to heat water for use by the user.

It is to be appreciated that, should there be an additional hot water demand, the heated fluid in the upper portion of fluid pathway III may be diverted into fluid pathway IV and subsequently fluid pathway VII to thermal store 80 to heat a hot water supply.

Once the measured air temperature has been reduced to the desired air temperature, and no additional cooling is required, electrical charge to thermoelectric device 112 is slow reduced.

The thermoelectric technologies used in the system of the present invention allow the heating and cooling of the local environment and the generation of hot water via the thermal store 80 to be undertaken more quickly than conventional systems that are dependent on refrigerants. In addition, the thermoelectric technology is more easily linked to other domestic renewal technologies being employed in homes such as photovoltaic (PV) lighting systems and other solar battery driven technologies.

Further, second thermoelectric device 112 is operable, for example on demand by a user via the user interface, or via one or more pre-programmed instructions, to operate to provide heated water for supply to a user. When operation of second thermoelectric device 112 is initiated, heat is generated at first surface 113 of array 114. This heat is absorbed across heat sink 124 and heats water in fluid pathway VII. At the same time, the opposing side 115 of array 114 becomes cool, thereby cooling fluid for onward circulation into fluid pathway VIII and then fluid pathway III, as described above. Thus, the system 111 of the described embodiment is operable to increase or decrease the temperature of the local environment in line with a user's preferences input into the system 111 via a user interface and controller 100. In addition, the system 111 is operable to provide heated water for use by a user, either on demand or in accordance with preprogramed preferences including water temperature and/or time of day.

It is to be noted that, whether in Cooling Mode or Heating Mode, valves 98, 99 remain closed to fluid pathway III until there is a hot water demand. At this point, valves 98, 99 open to fluid circuit III.

In the event that there is a hot water demand when there is neither a Heating nor a Cooling ventilation requirement i.e. when the desired temperature is the same as the measured temperature, valves 90, 92 are closed so that there is a closed cooled fluid circuit in fluid pathway VIII.

Claims

CLAIMS: 1. A system for the control of air temperature of a local environment and the storage of thermal energy, the system comprising: -a controller operable to receive a threshold temperature; - a sensor in electrical communication with the controller, the sensor being operable to measure the air temperature of the local environment and transmit a measured air temperature to the controller; 10 - a first thermoelectric device in electrical communication with the controller, the first thermoelectric device comprising: a first plate and a second plate with an array of Peltier devices arranged therebetween; a first heat sink in thermal communication with the first plate; and a second heat sink in thermal communication with the second plate; - a heat exchanger unit in electrical communication with the controller, the heat exchanger unit comprising: a first heat exchanger in thermal communication with a first air passage, and a second heat exchanger in thermal communication with a second air passage, the first and second air passages in fluid communication with the local environment; and third and fourth air passages, each in fluid communication with an external environment, wherein at least the first and third air passages are in fluid communication with one another and at least the second and fourth air passages are in fluid communication with one another; -a first fan located at the first air passage and a second fan located at the second air passage; - a thermal store; - a first fluid circuit between the first plate and the first heat exchanger, a second fluid circuit between the first plate and the thermal store, and a third fluid circuit between the second plate and the second heat exchanger, wherein, on receipt of a measured air temperature by the controller that is less than the threshold air temperature, the controller is operable to supply power to the thermoelectric device to heat the first heat sink and cool the second heat sink, and to open the first and third fluid circuits and close the second fluid circuit, and to operate the first fan to expel heated air from the heat exchanger unit through the first air passage into the local environment,_ and to operate the second fan to extract cooled air away from the local environment through the second air passage towards the fourth air passage; and wherein, when the measured air temperature received by the controller reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device, close the first and third fluid circuits and open the second fluid circuit.
2. A system as claimed in claim 1 wherein on receipt of a measured ambient air temperature by the controller that is greater than the threshold ambient air temperature, the controller is operable to supply power to the thermoelectric device to heat the second heat sink and cool the first heat sink, and to open the first and third fluid circuits and close the second fluid circuit; and to operate the first fan to expel cooled air from the heat exchanger unit through the first air passage into the local environment, and to operate the second fan to extract air away from the local environment through the second air passage towards the fourth air passage; and when the measured air temperature reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device and stop the operation of the first and second fans.
3. A system for the control of air temperature of a local environment and the storage of thermal energy, the system comprising: -a controller operable to receive a threshold temperature; -a sensor in electrical communication with the controller, the sensor being operable to measure the air temperature of the local environment and transmit a measured air temperature to the controller; -a first thermoelectric device in electrical communication with the controller, the thermoelectric device comprising a first plate and a second plate with an array of Peltier devices arranged therebetween, and a first heat sink in thermal communication with the first plate and a second heat sink in thermal communication with the second plate; -a heat exchanger unit in electrical communication with the controller, the heat exchanger unit comprising: a first heat exchanger in thermal communication with a first air passage, and a second heat exchanger in thermal communication with a second air passage, the first and second air passages in fluid communication with the local environment; and third and fourth air passages, each in fluid communication with an external environment, wherein at least the first and third air passages are in fluid communication with one another and at least the second and fourth air passages are in fluid communication with one another; -a first fan located at the first air passage and a second fan located at the second air passage; -a thermal store; -a first fluid circuit between the first plate and the first heat exchanger, a second fluid circuit between the first plate and the thermal store, and a third fluid circuit between the second plate and the second heat exchanger, wherein, on receipt of a measured air temperature by the controller that is greater than the threshold air temperature, the controller is operable to supply power to the thermoelectric device to heat the second heat sink and cool the first heat sink, and to open the first and third fluid circuits and close the second fluid circuit, and to operate the first fan to expel air from the heat exchanger unit through the first air passage into the local environment, and to operate the second fan to extract air away from the local environment through the second air passage towards the fourth air passage; and when the measured air temperature reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device and stop the operation of the first and second fans.
4. A system as claimed in claim 3, wherein on receipt of a measured air temperature by the controller that is less than the threshold air temperature, the controller is operable to supply power to the first thermoelectric device to heat the first heat sink and cool the second heat sink, and to open the first and third fluid circuits and close the second fluid circuit, and to operate the first fan to expel heated air from the heat exchanger unit through the first air passage into the local environments and to operate the second fan to extract cooled air away from the local environment through the second air passage towards the fourth air passage; and wherein, when the measured air temperature received by the controller reaches the threshold air temperature, the controller is operable to reduce power to the thermoelectric device, close the first and third fluid circuits and open the second fluid circuit.
5. A system as claimed in any one of claims 2 to 4, further comprising a second thermo-electric device located at the thermal store and in communication with the controller, the second thermal electric device comprising a first plate and a second plate with an array of Peltier devices arranged therebetween, a first heat sink in thermal communication with the first plate and a second heat sink in thermal communication with the second plate, wherein the system further comprises a fourth fluid circuit between the second plate and the second heat exchanger, and a fifth fluid circuit 6. 7. 8. 9.between the second plate and the third fluid circuit, and a fifth circuit between the second plate and the first heat exchanger, wherein when additional cooling of the local environment is required, the controller is operable to supply power to the second thermoelectric device to heat the first heat sink and cool the second heat sink, and to close the third fluid circuit and open the fourth and fifth fluid circuits, and to continue operation of the first and second fans.A system as claimed in any preceding claim, wherein the system further comprises a user interface operable by a user to manually input the threshold air temperature.A system as claimed in any preceding claim, wherein a plurality of thermally conductive pipes extend from respective first and second plates of respective first and second thermo-electric devices at least partially through the respective first and second heat sinks of respective first and second thermo-electric devices.A system as claimed in any preceding claim, wherein the array of Peltier devices of each respective thermo-electric device is mounted within a heat shield which is located between the first and second plates of respective thermo-electric devices.A system as claimed in claim 8, wherein a vapour chamber is provided between the heat shield and the respective first and second plates.