A cooling apparatus and method

Abstract

A thermochemical charging unit 2 for cooling a consuming unit 3 has an input 10 to receive air as a first working fluid during a charging operation and an output for air as a second working fluid to c

Description

The present disclosure relates to cooling, for example cooling of one or more spaces such as a cool storage space, a mobile storage place or a building. More particularly, apparatuses and methods for generating and storing thermal energy for cooling are disclosed. Cooling systems can utilise thermal energy storage (TES) materials where the material is cooled, or charged, and cold energy can be stored in the TES material. The stored thermal (cold) energy can then be released from the TES material. It would be desirable to be able to store more thermal energy than what is afforded by conventional sensible and latent heat based thermal energy storage (TES) techniques. A thermochemical energy storage system can store thermal energy via reversible chemical reactions or sorption processes between at least two materials. Upon combination or separation of two substances, thermal energy in form of heat can be absorbed or released. Such thermochemical energy storage system can be configured to produce and store cold energy, providing efficient use of, e.g., renewable energy, waste heat and off-peak electricity. The system can be used for providing various services such as peaking shaving and charging. Accordingly, in one aspect there is provided a thermochemical charging unit for a cooling system according to claim 1. Optional or preferred features are defined in dependent claims 2 to 15. In another aspect there is provided a system for cooling at least one space according to claims 16 to 20. In yet another aspect there is also provided method of cooling at least one space according to any of claims 21 to 35. A computer program product may also be provided for controlling the operation of at least a part of the herein described apparatus and system for use in implementing the claimed method. Various examples of how the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a system for cooling a consuming unit in accordance with an example; Figure 2 is a schematic diagram of a system in accordance with an example where air is cooled and circulated into a cold storage space; Figure 3 is a schematic diagram of a system in accordance with an example where a secondary coolant circulation system is used for providing cold energy to a cold storage space; Figure 4 is a is a schematic diagram of a thermochemical charging apparatus in accordance with an example; Figure 5 is a flow chart for a method in accordance with an example; and Figure 6 shows a use example of a cold storage space. Examples of apparatuses and methods for a cooling system are described next with reference to the Figures. It is noted that in the presentations are schematic and not in scale. It is also noted that the following description gives an exemplifying description of some possibilities to practise the invention. Although the specification may refer to “an”, “one”, or “some” examples or embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same example of embodiment(s), or that a particular feature only applies to a single example or embodiment. Single features of different examples and embodiments may also be combined to provide other embodiments. Cooling systems explained in more detail below utilise thermal energy storage materials. More particularly, the cooling systems are based on charging and discharging reactions and / or sorption processes taking place between a thermochemical material (TCM) or a composite TCM (CTCM) and a working fluid. An example of suitable working fluid is water vapour containing air. Other working fluids are also possible. Water vapour in the air is considered currently the cheapest and most green option, and therefore is currently preferred option. Reversibility is a core characteristic of thermochemical materials. Thermochemical materials (TCMs), also referred to as thermochemical energy storage (TCES) materials, can store thermal (heat or cool) energy through reversible chemical reactions and / or sorption processes. The basic concept of thermochemical energy storage is to store energy via chemical reaction and / or sorption processes between at least two materials. Upon combination or separation of the two substances, heat is absorbed or released. TCES materials used in the herein disclosed embodiments can generally store more energy than such conventional sensible and latent heat thermal energy storage (TES) techniques. Working fluid such as air can be used to provide moisture I energy carrier and is not as such involved in the reaction and / or sorption processes. The air does nevertheless affect heat and mass transfer, as well as reaction / sorption kinetics. A working fluid such as air is needed to enable the process where reaction / sorption is taking place between a TCM or composite TCM, and the water vapor in the air. Examples of TCM materials comprise silica gel, zeolites, activated carbon, and salt hydrates, as well as composite thermochemical materials (CTCMs) using the above TCMs. CTCMs can offer several favourable characteristics and are considered more robust in terms of cycle life than pure TCMs. Composite TCMs (CTCMs) use a host material such as inorganic materials for TCM, particularly hydrated or hydratable inorganic salts, or their mixtures. The host material can be of a size range of 0.01 to 10mm, while the TCM (hydrated / hydratable inorganic salt) can have a size range of 0.01pm to >100 pm. Additionally, a binder, and a flow aid can be used for making the CTCMs. A specific example of the composite TCMs (CTCMs) comprises MgSO4.7H2O and MgO composite with MgO being the host. Details of these materials are available for example from WO2023 / 1521134A1. Fig. 1 shows an illustrative diagram of a cooling system 1 comprising a TCM based cold generation unit or refrigeration unit 2. This unit can also store thermal energy. A second thermal energy storage material then consumes the generated cold. This can be provided by a phase change material (PCM) or a composite PCM (CPCM) within or closely by a consuming unit 3. The PCM or CPCM can be encapsulated within cooling elements arranged in suitable locations within or adjacent to the consuming unit 3. An example consuming unit 3 comprises a container providing an insulated cooling space or a cool storage space 4. Use of PCMs as a thermal energy storage medium is known. A suitable phase change material has a composition which absorbs or releases heat isothermally, or substantially isothermally, by transitioning, in a respective transition direction, between a first phase state and a second phase state at a predetermined transition temperature determined by specific applications. The temperature of the PCM can change substantially when temperature is different from the transition temperature and the PCM exhibits behaviour of a sensible heat storage material. Different phase change materials or composite phase change materials have different operating temperature ranges. Suitable example PCMs for thermal (cold) energy storage, at temperatures below ~15°C, comprise organic, inorganic, and eutectic PCM materials. Organic PCM examples can include tetradecane, n-Tetradecane, Paraffin C14, Formic acid, Polyglycol E400, n-Pentadecane, Paraffin C15, Tetrabutyl ammonium bromide, Isopropyl palmitatelsopropyl stearate, Propyl palmitate, Caprylic acid, Dimethyl sulphoxide, and Paraffin C16, Acetic acid. Examples of other suitable PCMs comprise Polyethylene glycol 600, Glycerine, n-Hexadecane, n-Heptadecane, Butyl stearate H2O, H2O + polyacrylamide, K2HPO46H2O, LiCIO3 3H2O, ZnCl2 3H2O, K2HPO46H2O, NaOH (3 / 2 H2O), NaOH, Na2CrO4WH2O, KF4H2O, 91.67% tetradecane - 8.33% hexadecane, Hexadecane - tetradecane (2:3-0:1 by volume), Tetradecane - docosane, Tetradecane - geneicosane, Caprylic acid -lauric acid (9:1 by mol), 94% tetradecane - 6% tetradeconol, 96% Tetradecane -4% tetradeconol, 94% Tetradecane - 6% tetradeconol, Lauryl alcohol - caprylic acid (2:3 by quality), Pentadecane - heneicosane, Caprylic acid - palmitic acid (2:3 by quality), C14 - C15 - C16 - C17 - C18 (33.4:47.3:16.3:2.6:0.4), Dodecanol -caprylic acid (40.6:59.4 by quality), Pentadecane - docosane, Pentadecane -octadecane, Hexadecane - tetradecane, Capric acid - lauric acid (65:35 by mol) with 10% cineole, Capric acid - lauric acid (65:35 by mol) with 10% methyl salicilate. In accordance with an example the consuming unit comprises cooling elements formed of composite phase change material (CPCM). Composite phase change materials can exhibit improved thermal charging / discharging performance due to enhanced thermal conductivity, and improved physical and chemical stability through reducing supercooling and / or phase separation. Combined operation of TCM / CTCM and PCM / CPCM based units can be advantageously utilised to deliver multifunction of load shift, and stable cooling temperature and cooling rate. In addition, environmentally friendly refrigeration, and easy end of life management of the materials can be provided. The thermochemical-based cold generation unit 2 of Fug. 1 comprises a TCM / CTCM reactor 14 for the generation of cold energy, carried by the coolant for input into the cold energy consuming or cooling unit 3. Unit 2 can also comprise a thermal energy store for cold production. The cold storage or cooling space 4 of the consuming unit 3 can comprise cooling elements 30 containing phase change material (PCM or CPCM). The cooling space 4 and cooling elements 30 therein can be surrounded by appropriate insulation material 31. The consuming unit can be provided, e.g., inside a container or the like insulated space for cold storage. The consuming unit 3 can be stationary or mobile, e.g., mounted on a vehicle or a unit that can be transported to a different location after charging. Appropriate fluid connections for connecting the fluid circulation conduits between the TCM based cold generation and / or thermal energy storage unit 2 and the phase change material based consuming unit 3 are provided for enabling circulation of fluid between the charging and consuming units. The connections can be releasable. A blower 11 can be releasably connected to a container on a vehicle or another mobile container so that air can be pumped between the container and the TCM reactor to enable the charging operations when needed. More than one cold consuming unit may be provided. One TCM charger unit can serve several consuming units. The outlet temperature of the TCM charger can vary with time. A PCM channel element 24 can be attached to the TCM charger unit 2 to store an appropriate amount of cold energy to regulate the temperature. This arrangement can be provided to give a constant temperature output to the consuming unit 3. The consuming unit 3 providing at least one cooling space 4, where PCM / CPCM contained in the cooling elements provides the cold energy needed by the stored products. The PCM / CPCM within consuming unit 3 can also have the function of stabilising the temperature in the cooling space(s) 4. Operationally, cold energy can be produced by the TCM unit 2 at optimal times, for example during off-peak hours. The discharge of TCM unit 2 can be either or both at peak and off-peak hours. The PCM channels element 24 can be configured to have the main function of regulating the temperature of the working fluid entering the cooling space 4. The PCM channels element 24 can also be designed to store considerable amount of cold energy produced during off-peak hours, e.g., when the consuming unit 3 is not available. This may occur, e.g., when a mobile consuming unit with a cooling space is away or when the cooling unit 3 does not need charging. In the shown example, the PCM storage entities comprising PCM channels 24 and consuming unit 3 provided with cooling elements 30 use air as the working fluid cooled by TCM refrigerator unit 2. The cooled air flows through the PCM channels 24 to regulate the temperature. The PCM channels element 24 can also store some of the cold energy before the energy in the flow reaches consuming unit 3 for charging the PCM modules 30 in the consuming unit 3. The PCM channels 24 can also comprise several flow channels such that each, or at least some of the channels are filled with different PCMs / CPCMs for charging different consuming units for different cold storage temperature requirements. This can be provided, for example, to service a plurality of cooling spaces with different cooling requirements. The charge and discharge processes can be provided at different stages or be simultaneous, depending on the application scenarios. The following discusses an example where two operational stages are provided in the operation of the system. In a first stage the TCM in the TCM charger unit 2 is charged. In this stage the TCM is charged while the consuming unit 3 is not provided cooling energy by the TCM charger unit 2. In the second stage the phase change material of the consuming unit 3 is charged and the TCM charger unit 2 correspondingly discharged. In this stage the TCM charger unit 2 is already in the charged state and discharge thereof can thus be used to charge the consuming unit 3. In the shown example the consuming unit 3 comprises PCM modules 30 located in the cooling space 4 of the container. The PCM modules 30 are filled with phase change material (PCM) or composite PCM (CPCM). The PCM channels element 24 located between the charging unit 2 and the consuming unit 3 can also be filled with PCM or CPCM. Both can be charged with cold energy generated by the TCM charger and carried thereto by the working fluid. The PCM / CPCM filled in the PCM modules 30 is preferred to have a slightly higher melting temperature than the PCM / CPCM of the PCM channels 24. This can provide more effective charging operations. In the charging stage of the cooling space 4, moist condensed from air from the cooling space of the consuming unit 3 at the end of the cycle can be exhausted or kept inside the cooling space for energy efficiency reasons due to the cold energy in the water. Also, in case of storing fresh produces the water is advantageous in view of freshness and longer shelf life of the produce. The exhaust moist air is driven by the blower 11 to the input 10 of the TCM charger unit 2. From the input 10 the moist air is led to a TCM reactor 14 of the TCM charger unit 2 during the discharge of the charging unit. Various possible components of the TCM charger unit 2 and the consuming unit 3 and overall operation of system 1 are described next. In operation when the TCM unit 2 is charged the blower 11 pumps air in ambient temperature from the environment through input 10 into the TCM charger unit 2. The input air is heated in a heater 12. Air heated by the heater 12 is then used to dry out a TCM material in the TCM reactor 14. The TCM stores the ‘dryness’ which can then be turned into thermal energy during discharging. Valve V2 can be closed and valve V1 opened during charging. Heat exchanger 13 (HEX 1) can be provided for recovery of some of the excess heat from the exhaust of the TCM reactor 14 via conduit 25 during charging. Flow in the conduit 25 can be controlled by valve V1 / 26. Operation of the HEX 1 can also be used to condense exit water vapour. Charging is complete when the TCM material in the reactor becomes as dry as possible in practise. This can be when the humidity level of the air exiting the TCM reactor is approaching the humidity level at the inlet. It shall be appreciated that this state is not necessarily reached in all practical implementations. In accordance with a possible mode of operation when discharging the TCM charger unit 2 for charging the PCM channels element 24 and the PCM modules 30 within the consuming unit 3, air can be recirculated between the container unit 3 and the TCM charger unit 2 via conduit 32. A blower can be connected to blow air from the internal cooling space 4 of the consuming unit 3 into the TCM charger unit 2 so that the blower can pump moist air to the TCM reactor 14 via the input 10. This blower can be the same blower 11 as described above for the charging stage or a separate blower. At this stage the moist air may have temperature of about 10 -15 °C. The heater 12 is at deactivated state at this stage. Valve V1 126 can be closed during the discharging of TCM unit. A bypass can be provided between the blower and the reactor since heat exchanger 10 and the heater 12 have no function during TCM reactor discharging for charging the PCM / CPCM elements of the regulator entity 24 and modules 30 in the consuming unit 3. The moist air hydrates the material in the TCM reactor 14. In so doing the moist air is dried and becomes heated. A process to take advantage of the dryness of this air is then started to create cold. The cooling can involve several steps. Some cooling of the warm dry air can be conducted at a heat exchanger 15 (HEX2) with the ambient temperature. Electrical energy may be consumed to operate a fan 16 to enhance the heat exchange. The flow of air from the heat exchanger 15 is then split to two at junction 18. A valve system can be provided to control flow rates in the two streams. A first flow of the dry air 17 is then passed through a humidifier 20. Water introduced to the air absorbs heat from the dry air to evaporate that water, thereby reducing the temperature of the first flow of dry air. A pump can be provided to circulate the water. Part of the water will be evaporated, and the temperature of the remaining circulated water will drop down as it passes through the humidifier. The water need not be intentionally cooled and can be introduced at room temperature. To lower the temperature of the output air further the humidified first flow of dry air 17 is guided into a third heat exchanger 21 with a second flow of dry air 19 from HEX2 to give this second flow of dry air a lower starting temperature before the second flow 19 is humidified by a second humidifier 23 to lower its temperature further. The first air flow 17 is guided out through outlet 22 from the third heat exchanger 21 while the second airflow 19 is led into a second humidifier 23. Part of the air in flow 17 is cooled in the first humidifier and then it is used to precool the second part of air flow 19 in the heat exchanger 21. Then the second part of air flow will be further cooled in the second humidifier 23. The temperature in the first humidifier keeps reducing until the air gets saturated. This will limit the outlet temperature. By splitting the air into two streams it is possible to reduce the inlet temperature to the second humidifier and allow the temperature to drop further as the second flow is still dry. By means of this arrangement the temperature of the second part of the air flow is considerably lower than the first part. This can be used to maximise the temperature drop. Through control, the airflow 17 exhausted from 22 approaches the ambient condition, so little energy is lost. After passing through the second humidifier the air is no longer dry but has become cold and moist. For example, at this stage the air can cool to 2 - 7 °C. This range is only given as an example, and not all cooling applications require such a low temperature. Also, some cooling applications only require use of the first humidifier instead of the two. Other applications may require three stages through split of the second part of air flow further to produce even lower temperature. Even more than three stages may be provided. The output air from the second humidifier 23 is led to PCM channels element 24 which can be used for thermal regulation of the output air temperature from the second humidifier. The air is pumped from the PCM channels element 24 to the cooling space 4 of a container comprising consuming unit 3 to provide cooling of a storage space. The different PCMs in different channels of the PCM channels element 24 can be used for regulating the temperatures to required ranges to meet the different cold storage temperature charging applications. At this stage the temperatures of the air introduced into the cooling space 4 can be, for example, about 7 °C. PCM modules 30 at the cooling space 4 store the cold energy from the TCM charger for later use. In case of use with mobile containers or the like the PCM modules 30 allow the container to stay at constant temperature even when charging unit is disconnected. In accordance with an example for applications requiring higher temperature, e.g., 10-15°C, the output air from the first humidifier 20 may be led to PCM channels element 24, or some channels of the PCM channels element 24. The various devices involved in the operation consume energy. For example, the heater 12, the blower 11 and the fan 16 consume electricity. Electricity can be sourced from off-peak electricity, waste heat or generated from renewable sources. For example, solar, thermal, wind energy and so on may be utilised for generation of the electricity. Fig. 2 shows an example of combined TCM-PCM cooling system 40 with direct air circulation. The system is configured for direct charging using cooled air from the TCM charger regulated by the PCM channels element (not shown in Fig. 2). This configuration is particularly suitable for slow and medium charging rates due to the use of air as the heat transfer fluid. A PCM based cold storage container 43 provides a consuming unit that comprises an internal cold storage space 44 for goods. The PCM based cold storage container can be stationary or mobile. The cold space 44 is insulated by appropriate insulation 47. The consuming unit can be any space that needs cooling to an appropriate temperature range, for example a warehouse or the like. PCM modules or composite PCM (CPCM) modules 45 can be provided on the internal walls of the cold storage unit 43. Modules shaped as blocks can be assembled to form arrays of blocks of phase change material on the internal walls of the cold storage space 44. The modules with or without gaps between them may cover the entire internal surface area of the walls (including ceiling and floor), or only a part of the internal surfaces. Each block may comprise a body of the phase change material within an outer case which seals the phase change material within the block to avoid leakage of the phase change material during successive thermal charging / thermal discharging cycles. When CPCM is used, an outer casing may also be used. This, however, is not essential for all CPCMs as some of the CPCMs can provide a shape stabilised structure. The PCM or CPCM modules on the floor of the unit can be embedded within a metallic support 46 or the like. The embedded CPM or CPCM modules on the floor can be arranged to provide functions such as structural support of goods, condensed cold water storage, and humidity provision. The structure may also provide channels for discharge of water after a delivery of goods. Thermochemical-based cold generation unit 50 is connected to receive air from the cold storage space 44 via its inlet 51 connected to the outlet 42 of the cold storage space. Cooled air is fed back to the cold storage space 44 via inlet 41. This completes the air circulation without losing cold energy in the air. Internal components of the cold generation unit 43 are shown to comprise a blower 52 pushing air towards a recovery heat exchanger 53 followed by a heater 54. These components correspond to components 11, 13, and 12 of Fig. 1, respectively, and are not explained again. The TCM reactor part is different in that two reactors 55 and 56 are provided. The two-reactor arrangement can have the same amount of TCM material as a single reactor but provides improved flexibility in terms of features such as reducing pressure drop, enhancing heat and mass transfer and increasing dryness, as well as the managing the total height / length. The two reactors can have different particle sizes and / or different length / height-diameter ratio to achieve the above flexibility. Two reactors can also be used as a way to provide simultaneous charging and discharging operations with additional connections and valves. The reactor unit is connected to a heat exchanger 57 and a humidifier 58. The humidifier can be provided with a pump 59 for enhanced operation. First valve (V1) 62 is for controlling flow of air from the TCM reactor unit to the recovery heat exchanger 53. Second valve (V2) 63 is for controlling the flow of the air from the TCM reactor unit to the discharging stage. Fig. 2 further shows a charging connection unit 65 located between the thermochemical-based cold generation unit 50 and the cold storage unit 43. The charging connection unit can comprise a TCM booster attached to the container for extra-long duration of the discharging stage. This can be particularly advantageous for the mobile cooling unit applications in which case the booster would be attached to the unit 43. The booster can use the same principle as the thermochemical charger but be of simpler, smaller and lighter construction with the exact size and weight determined by the needs of the application. The charging connection unit 65 can also include a PCM channels element for stabilising the temperature of the air. Fig. 3 shows an example of a combined TCM-PCM cooling system 70 provided with a secondary coolant circulation. This system is mainly for medium to fast charging. The consuming unit comprises a PCM based cold storage system 71. A distinction to Fig. 2 is that the cooling space 74 is cooled by PCM modules that are charged by a liquid coolant circulating with appropriate conduits in contact with the PCM modules rather than use of circulating air. The basic principles of the TCM based cold generation unit 72 can correspond to the unit 50 of Fig. 2 or unit 2 in Fig. 1. The PCM modules can comprise composite PCM. In Fig. 3 system a charging connection unit 75 between the cold generating unit 72 and the cold consuming unit 71 provides a second coolant circulation system 77. The charging connection unit 75 comprises at least one cold energy storage heat exchanger 76 where cold energy from the cold air output in a circulation loop 74 from the cold generation unit 72 is transferred into a second coolant fluid circulated in the second fluid circulation system 77. The second coolant circulation system comprises cold energy releasing conduits 78 extending into contact with the PCM modules to enable the storage space to be kept cool. Fig. 3 shows an example with three coolant circulating pipes. The number of pipes can be less than three or can be more, even considerably more than three depending on the charging power needed. The circled enlarged detail illustrates an example of the arrangement of the pipes 78, the PCM modules 45, and insulation 47. The coolant circulation pipes 78 can extend the entire length of the PCM modules 45 or only a part of the length of the modules. The coolant circulation pipes can extend in different patterns than the shown lengthwise arrangement. Also, the coolant circulation pipes do not necessarily need to extend between the PCM modules but can also be placed, e.g., under the PCM modules, or even be embedded within the PCM modules as an integrated part. These pipes can have fins in the inside or outside to enhance heat transfer further. The arrangement can provide a single charging inlet or multiple charging inlets. A thermochemical booster can also be provided in the charging connection unit 75. This can be attached to the cooling container 71 in mobile applications. Integrated enroute renewable energy charging may also be provided. For example, solar panels can be installed on the roof of the containers to provide energy source for charging the thermochemical booster. Fig. 4 shows further example of a thermochemical charging unit. In this nonlimiting example a consuming unit 89 is shows to be provided within a building, for example a residential building or a commercial building. The illustrated charging unit comprises a two-stage arrangement to provide a lower temperature cooling. For example, a coolant temperature below about 5 °C may be provided. Air is pushed to the reactor unit 80 by a blower 81 at the air inlet via a heat exchanger 82 and heater element 83 as explained above. The reactors 84 and 85 can be controlled via respective three-way valves 86 and 87 selectively connecting and disconnecting the reactors to the piping so that simultaneous charging and discharging by the TCM reactor unt is enabled. A multiple stage configuration can provide improved flexibility with which one or more of the TCM reactors can be charged while discharging at least one TCM reactor. The number of TCM reactors can be one, two, or more. The reactors can be selectively operated. Fig. 5 is a flowchart for operation according to one example for a method for cooling a consuming unit. The method comprises receiving at 100 in a thermochemical charging unit air for use as a first working fluid during a charging operation or a second working fluid during a discharging operation. The thermochemical charging unit comprises at least one thermochemical reactor containing thermochemical material (TCM) as explained above. The thermochemical charging unit is charged at 102 with thermal energy by thermochemical processes including either or both of reversible reactions and reversible sorption. The at least one thermochemical reactor increases the dryness of the thermochemical material by means of the first working fluid during charging, and stores generated thermal energy for generation of cold energy. It further uses at 104 reverse thermochemical processes to transfer the generated thermal energy for cold generation into the second working fluid for discharging thermal energy from the thermochemical charging unit. The discharged second working fluid is guided at 106 into at least one heat exchanger and at least one humidifier for reducing further the temperature of the second working fluid output from the at least one thermochemical reactor. The second working fluid can then be used at 108 to charge a phase change material based thermal energy storage medium of a consuming unit. The method can comprise heating the air used as the first working fluid before input into the at least one thermochemical reactor. A heat exchanger may be used to transfer thermal energy from the at least one thermochemical reactor to the first working gas before input of the first working fluid into the at least one thermochemical reactor. At least one control valve can be operated to selectively circulate air during charging and / or discharging. The second working fluid can be guided into an intermediate thermal energy storage element between the thermochemical charging unit and the consuming unit. The intermediate thermal energy storage element can comprise at least one type of phase change material (PCM) for regulating the thermal energy input into the consuming unit. Different thermal energy inputs can be provided for the consuming unit by the intermediate thermal energy storage element. This can be provided by means of at least two different flow channels provided with different phase change materials. At least two thermochemical reactors can be operated such that simultaneous charging and discharging is provided. The second working fluid can be input into a booster thermochemical reactor. The method can comprise cooling the consuming unit by circulating the second working fluid into at least one space. Alternatively, or in addition, thermal energy can be transferred from the second working fluid to a second coolant circulation loop extending into at least one space. Thermal energy can be transferred from the second working fluid into modules of phase change material mounted within the consuming unit. The modules of phase change material withing the consuming unit can comprise composite phase change material. Fig. 6 shows an example of a container 93 comprising a cooling space 94 as explained above mounted on a vehicle 90. The container is provided with an inlet 95 for receiving cooling fluid from a charging unit as explained above. An outlet 96 for coolant, with its cold energy already consumed, is also shown. The inlet and outlet can be releasably connected to the charging unit via appropriate connectors. A TCM charger system disclosed herein has capability to shift the cooling load to off-peak times and efficient storing of the generated cold energy for later consumption. It can use renewable energy, waste heat and off-peak electricity to operate the charging of the system, Also, clean and environmentally friendly cooling system can be provided due to the use of water and air as the working fluid and storage material pair. The disclosed system provides flexibility for both stationary and mobile cooling applications though flexible integration. It shall also be appreciated that the system can be used for both heating and cooling with storage functions. The system can provide more sustainable and good overall system Coefficient of Performance (COP) compared with other cooling technologies where vapour compression cycles are not used. The foregoing description provides byway of exemplary and non-limiting examples a full and informative description of exemplary embodiments of the invention. It is noted that although the above detailed examples have been described with reference to certain processes, applications and apparatuses there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention. For example, instead of cooling a space a physical structure can be cooled. In particular, the different embodiments have been described as examples. Different features from different embodiments may be combined. Various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. Various modifications to the illustrated embodiments as described hereinabove will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.

Claims

1. A thermochemical charging unit for a cooling system comprising:at least one input for receiving air for use as a first working fluid during charging operation or a second working fluid during discharging operation,at least one output of the second working fluid to charge a phase change material based thermal energy storage medium of a consuming unit,at least one thermochemical reactor containing thermochemical material (TCM) and configured to provide thermochemical processes based on reversible reaction and / or reversible sorption processes for charging the thermochemical charging unit with thermal energy for cold energy generation and discharging said thermal energy from the thermochemical charging unit in the form of cold energy, wherein the at least one thermochemical reactor increases the dryness of the thermochemical material by means of the first working fluid during charging, stores generated thermal energy for cold generation, and uses reverse thermochemical processes to transfer the generated thermal energy for cold generation into the second working fluid during discharging,at least one heat exchanger for reducing the temperature of the second working fluid output from the at least one thermochemical reactor prior to use of the second working fluid in cooling of phase change material (PCM) based thermal energy storage medium of the consuming unit, andat least one humidifier for reducing the temperature of the second working fluid output from the at least one thermochemical reactor prior to use of output of the second working fluid in cooling of the phase change material based thermal energy storage medium of the consuming unit.

2. A thermochemical charging unit of claim 1 comprising at least one heater configured to heat the air used as the first working fluid before input into the at least one thermochemical reactor.

3. A thermochemical charging unit of claim 1 or 2 comprising at least one heat exchanger configured to transfer thermal energy from the at least onethermochemical reactor to the air used as the first working fluid before input of the first working fluid into the at least one thermochemical reactor.

4. A thermochemical charging unit of any preceding claim, wherein the at least one thermochemical reactor comprises thermochemical material (TCM).

5. A thermochemical charging unit of any preceding claim, comprising a blower for circulating air in the thermochemical charging unit.

6. A thermochemical charging unit of any preceding claim, comprising at least one control valve for controlling selective circulation of air during charging.

7. A thermochemical charging unit of any preceding claim, comprising at least one control valve for controlling selective circulation of air during discharging.

8. A thermochemical charging unit of any preceding claim, wherein the output is connected to an intermediate thermal energy storage element between the thermochemical charging unit and the consuming unit, the intermediate thermal energy storage element comprising at least one type of phase change material (PCM).

9. A thermochemical charging unit of claim 8, wherein the intermediate thermal energy storage element is configured to regulate the thermal energy input into the consuming unit.

10. A thermochemical charging unit of claim 8 or 9, wherein the intermediate thermal energy storage element comprises different phase change material to provide different grades of thermal energy inputs into the consuming unit.

11. A thermochemical charging unit of any of claims 8 to 10, wherein the intermediate thermal energy storage element comprises at least two different flow channels provided with different phase change materials.

12. A thermochemical charging unit of any preceding claim, wherein the thermochemical material comprises composite thermochemical material.

13. A thermochemical charging unit of any preceding claim, comprising at least two thermochemical reactors.

14. A thermochemical charging unit of claim 13, wherein at least one thermochemical reactor is for charging and at least one thermochemical reactor is for simultaneous discharging.

15. A thermochemical charging unit of any preceding claim, wherein the output is connected to a booster thermochemical reactor.

16. A cooling system comprising a thermochemical charging unit of any preceding claim, further comprising a consuming unit comprising at least one space to be cooled by means of coolant generated by the thermochemical charging unit.

17. A cooling system of claim 16 wherein the air used as the second working fluid is circulated into the at least one space.

18. A cooling system of claim 16 further comprising a second coolant circulation loop extending into the at least one space and a heat exchanger between the air used as the second working fluid and the second coolant circulated in the second coolant circulation loop.

19. A cooling system of any of claims 16 to 18, wherein modules of phase change material are mounted on at least one internal surface of the at least one space.

20. A cooling system of claim 19, wherein the modules of phase change material comprise composite phase change material.

21. A method for cooling a consuming unit, comprising:receiving in a thermochemical charging unit air for use as a first working fluid during a charging operation or a second working fluid during a discharging operation, wherein the thermochemical charging unit comprises at least one thermochemical reactor containing thermochemical material (TCM),charging the thermochemical charging unit with thermal energy for cold energy generation by thermochemical processes based on reversible reactions and / or reversible sorption, wherein the at least one thermochemical reactor increases the dryness of the thermochemical material by means of the first working fluid during charging and stores generated thermal energy for cold energy generation,transferring by reverse thermochemical processes the thermal energy for cold energy generation into the second working fluid for discharging thermal energy from the thermochemical charging unit,guiding the discharged second working fluid into at least one heat exchanger and at least one humidifier for reducing the temperature of the second working fluid output from the at least one thermochemical reactor, andusing the second working fluid to charge a phase change material based thermal energy storage medium of a consuming unit with cold energy.

22. A method of claim 21 comprising heating the air used as the first working fluid before input into the at least one thermochemical reactor.

23. A method of claim 21 or 22 comprising transferring by a heat exchanger thermal energy from the at least one thermochemical reactor to the first working fluid before input of the first working fluid into the at least one thermochemical reactor.

24. A method of any of claims 21 to 23, wherein the at least one thermochemical reactor comprises composite thermochemical material (CTCM).

25. A method of any of claims 21 to 24, comprising operating at least one control valve to selectively circulate air during charging and / or discharging.

26. A method of any of claims 21 to 25, comprising guiding the second working fluid into an intermediate thermal energy storage element between the thermochemical charging unit and the consuming unit, the intermediate thermal energy storage element comprising at least one type of phase change material (PCM) and regulating the thermal energy input into the consuming unit.

27. A method of claim 26, comprising providing different thermal energy inputs into the consuming unit by an intermediate thermal energy storage element.

28. A method of any of claim 27, wherein the intermediate thermal energy storage element comprises at least two different flow channels provided with different phase change materials for proving the different grades of thermal energy inputs.

29. A method of any of claims 21 to 28, wherein the thermochemical material comprises composite thermochemical material.

30. A method of any of claims 21 to 29, wherein the thermochemical charging unit comprises at least two thermochemical reactors, the method comprising simultaneous charging by at least one thermochemical reactor and discharging by at least one other thermochemical reactor.

31. A method of any of claims 21 to 30, comprising inputting the second workingfluid into a booster thermochemical reactor.

32. A method of any of claims 21 to 31, comprising cooling the consuming unit by circulating the second working fluid into at least one space.

33. A method of any of claims 21 to 31, comprising transferring thermal energy from the second working fluid to a second coolant circulation loop extending into at least one space.

34. A method of any of claims 21 to 33, comprising transferring thermal energy from the second working fluid into modules of phase change material mounted within the consuming unit.5 35. A method of claim 34, wherein the modules of phase change materialcomprise composite phase change material.

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