Cooling system

Abstract

The application describes a cooling system comprising: one or more adsorption beds, each comprising adsorbent material for adsorbing a refrigerant and a heat exchanger for heating the adsorbent material to facilitate desorption of the refrigerant; a condenser connected to the one or more adsorption beds and arranged to condense a desorbed refrigerant vapour received from an adsorption bed into its liquid phase; an evaporator arranged to receive a liquid phase refrigerant from the condenser and evaporate the refrigerant causing cooling in a target area adjacent to the evaporator, wherein the evaporator is connected to the one or more adsorption beds such that a vapour phase refrigerant diffuses from the evaporator to a connected adsorption bed. The system is characterised in that the system further comprises an auxiliary gas control valve for directing a supply of an auxiliary gas to the evaporator to reduce a partial pressure of the refrigerant. The system provides a cooling system requiring less energy and of reduced weight and complexity compared to existing cooling systems.

Description

[0001] COOLING SYSTEM

[0002] FIELD OF THE INVENTION

[0003] The present invention is directed to a cooling system, more specifically an adsorption-based cooling system, particularly for application in the thermal management of electric vehicles.

[0004] BACKGROUND

[0005] Battery electric vehicles (EVs) are becoming increasingly common with many countries introducing targets requiring car manufactures to sell a certain proportion of electric vehicles and aiming to phase out petrol and diesel powered vehicles. As these EVs become more prevalent, ensuring the efficient and safe operation of high-capacity lithium-ion battery packs has emerged as a critical technical challenge.

[0006] Current state-of-the-art thermal management systems for EV batteries predominantly employ liquid cooling circuits using water-glycol mixtures, as well as traditional vapour compression cycles. These systems have proven effective in managing heat under normal operating conditions but have several significant drawbacks.

[0007] Firstly, conventional cooling systems often demand substantial power to maintain the optimal operating temperature of battery packs, particularly under high-load conditions or in extreme ambient temperatures. This increased energy consumption can adversely affect the overall driving range and efficiency of the vehicle.

[0008] Typical designs use separate cooling circuits for batteries, power electronics, and cabin environments. This segmentation not only adds complexity but also results in higher manufacturing and maintenance costs. The integration challenges are compounded when trying to achieve uniform temperature distribution across the battery pack, which is essential to prevent localised overheating.Many conventional systems also rely on high-pressure refrigerants, such as R134a and R1234yf, which are known to be environmentally harmful. Moreover, the inability of traditional systems to consistently regulate temperature heightens the risk of thermal runaway, a safety hazard associated with lithium-ion batteries and conventional thermal management solutions struggle to maintain battery performance. In regions with extreme temperatures, the risk of thermal events is magnified, potentially leading to degraded battery performance or even hazardous operating conditions.

[0009] There is accordingly a pressing need for a cooling system, particularly suited for battery thermal management systems, that integrates with existing vehicle architectures while minimising energy consumption, reducing environmental impact, and enhancing safety.

[0010] SUMMARY OF INVENTION

[0011] In a first aspect of the invention there is provided a cooling system comprising: one or more adsorption beds, each comprising adsorbent material for adsorbing a refrigerant and a heat exchanger for heating the adsorbent material to facilitate desorption of the refrigerant; a condenser connected to the one or more adsorption beds and arranged to condense a desorbed refrigerant vapour received from an adsorption bed into its liquid phase; an evaporator arranged to receive a liquid phase refrigerant from the condenser and evaporate the refrigerant causing cooling in a target area adjacent to the evaporator, wherein the evaporator is connected to the one or more adsorption beds such that a vapour phase refrigerant diffuses from the evaporator to a connected adsorption bed; the system characterised in that the system further comprises an auxiliary gas control valve for directing a flow of an auxiliary gas to the evaporator to reduce a partial pressure of the refrigerant.

[0012] The present invention makes progress in solving the above-identified issues with prior art thermal management systems, particularly when applied to cooling of thecomponents of an electric vehicle. Firstly, conventional cooling systems, particularly those based on vapour compression, have very high energy consumption, which directly impacts electric vehicle (EV) range and efficiency. The systems often need to power mechanical components such as compressors to provide the required pressure differentials across the system. The innovative adsorption based cooling approach of the present invention significantly reduces the input energy needed to drive the cooling. Firstly, adsorption and desorption from the adsorption beds can be controlled solely by controlling the temperature of the beds - either with an electrically powered heater or by leveraging waste heat from the system to drive the required temperature changes. Furthermore, the system does not require any pressure differential to be maintained but instead can operate under a substantially uniform pressure, instead, utilising partial pressure effects by providing the auxiliary gas to the evaporator to provide a partial pressure drop to drive the evaporation of the refrigerant and flow between the evaporator and adsorption bed.

[0013] The statement that the auxiliary gas control valve is “for directing a supply of an auxiliary gas to the evaporator to reduce a partial pressure of the refrigerant”, may be alternatively stated as the auxiliary gas control valve is configured to direct a flow (i.e. “supply”) of auxiliary gas (from the adsorption bed) to the evaporator to control a partial pressure of the refrigerant in the evaporator, i.e. to provide a partial pressure within a predetermined range, i.e. to provide a reduced partial pressure such that the refrigerant evaporators at a lower temperature.

[0014] In some examples, the auxiliary gas control valve is configured to control a supply of an auxiliary gas to the evaporator to control the partial pressure of the refrigerant. In some examples, the auxiliary gas control valve is configured to direct the auxiliary gas to the evaporator and control the flow rate of the auxiliary gas, thereby controlling the supply of auxiliary gas and the resulting partial pressure of the refrigerant. In other examples, the auxiliary gas control valve does not modulate the flow rate but simply directs the flow of auxiliary gas to evaporator. In particular the auxiliary gas control valve is configured to provide an auxiliary gas flow loop in which the auxiliary gas flows from the evaporator to the adsorptionbed and back via the auxiliary gas control valve to the evaporator. In this way, the flow of gas in the system is controlled solely by controlling the temperature of the adsorbent material of the adsorption bed.

[0015] In some examples the cooling system comprises a plurality of adsorption beds and the auxiliary gas control valve is configured to connect the evaporator to an auxiliary gas outlet of each adsorption bed. The auxiliary gas control valve may then be configured to switch the connection of the evaporator between the adsorption beds, such that an adsorption bed in an adsorption phase is connected via the auxiliary gas control valve to the evaporator. Alternatively stated, the auxiliary gas control valve may be configured to alternately direct the auxiliary gas from the first adsorption bed and then a second adsorption bed.

[0016] The fact that the system can operate without these mechanical parts also reduced complexity, weight and manufacturing cost. The lightweight system allows for integration into existing EV architectures and is scalable by simply adjusting the volume of adsorbent material.

[0017] The present invention leverages a sustainable adsorption cooling cycle utilising natural refrigerants such as ammonia for the refrigerant and hydrogen as the auxiliary gas (NH3 / H2). This enables efficient heat dissipation with minimal energy input, significantly improving the overall energy efficiency and environmental sustainability of electric vehicle operations.

[0018] Preferably the system comprises a controller (i.e. a control unit or processing unit) configured to control the supply of heat to the heat exchanger to heat the adsorbent material and provide desorption of the refrigerant when the adsorbent material is saturated. A change to the heating supply to the adsorbent material can change the ammonia flow in the evaporator and therefore can change the evaporation (cooling) power of the system.

[0019] Preferably the system comprises a controller (i.e. a control unit or processing unit) configured to control the auxiliary gas control valve to provide a supply of auxiliary gas to provide a reduced refrigerant partial pressure in the evaporator. Inparticular, the controller may be configured to selectively connect an auxiliary gas outlet of each adsorption bed to the evaporator. The controller may alternate the connection of the evaporator between the auxiliary gas outlet of each adsorption bed so that the auxiliary gas continuously flows to the evaporator. That is, while the adsorbent material of an adsorbent bed is undergoing adsorption of the refrigerant, the non-adsorbed auxiliary gas passes through the auxiliary gas outlet of the adsorption bed and flows via the auxiliary gas control valve to the evaporator. In this way, the evaporation temperature of the refrigerant is lowered to provide enhanced cooling effects.

[0020] Preferably the system comprises a first adsorption bed and a second adsorption bed, wherein the first and second adsorption bed are each connected to both the condenser and evaporator; wherein the system is configured to operate a reciprocal cycle in which one adsorption bed is undergoing desorption in which the refrigerant is desorbed from the absorbent material and flows to the condenser, while the other adsorption bed is undergoing adsorption in which the refrigerant is received from the evaporator and is adsorbed onto the adsorbent material. Although the system may be configured with a single adsorption bed to provide periodic cooling, preferably the system comprises at least two adsorption beds so that, at all times, at least one adsorption bed is undergoing adsorption with refrigerant evaporating in the evaporator to provide continuous or near continuous cooling. Preferably the system comprises a first adsorption bed and a second adsorption bed, wherein the system is configured such the first adsorption bed and second adsorption bed may be selectively placed in fluidic communication with the condenser and evaporator. The system may then be configured such that the first adsorption bed is placed in fluidic communication with the condenser when the heat exchanger of the first adsorption bed is heating the adsorbent material of the first adsorption bed and the second adsorption bed is placed in fluidic communication with the evaporator when the adsorbent material of the second adsorption bed is non-saturated and undergoing adsorption, and vice versa. In these examples, the auxiliary gas control valve is configured such that auxiliary gas from each adsorption bed flows to the evaporator. In particular, the auxiliary gas control valve is configured to alternately connect the first andsecond adsorption beds to the evaporator. In this way a continuous supply of the auxiliary gas is provided to the evaporator to maintain a partial pressure of the refrigerant in the evaporator.

[0021] The system preferably further comprises a refrigerant control valve configured to control the flow of refrigerant between each adsorption bed and the condenser and evaporator. The refrigerant control valve may be configured to selectively place each adsorption bed in fluidic communication with the evaporator or the condenser. The refrigerant control valve may be configured to selectively connect the adsorption beds with the condenser or refrigerant to provide a continuous cooling cycle in which each adsorption bed alternates between adsorption and desorption.

[0022] Preferably the refrigerant control valve is configured to control the flow of refrigerant for each adsorption bed to provide: a flow of desorbed refrigerant from the adsorption bed to the condenser when the adsorption bed is undergoing desorption; and a flow of evaporated refrigerant from the evaporator to the adsorption bed when the adsorption bed is undergoing adsorption.

[0023] Preferably the auxiliary gas control valve is configured to provide a flow of the auxiliary gas to the evaporator to provide a reduced partial pressure of the refrigerant in the evaporator Since the system does not have to maintain low pressures and / or pressure gradients it is also less prone to failure and is significantly less complex and costly.

[0024] Preferably the auxiliary gas control valve is configured to provide (i.e. facilitate) a flow of the auxiliary gas to the evaporator to provide a partial pressure gradient, once the auxiliary gas meets the liquid refrigerant in the evaporator, between the evaporator and a connected adsorption bed (i.e. a partial pressure drop in the evaporator), where the adsorbent material of the connected adsorption bed is nonsaturated, to facilitate diffusion of the refrigerant from evaporator to the connected adsorption bed.The cooling system is preferably pressurised with the auxiliary gas to provide a uniform system pressure. Preferably the system is pressurised with the auxiliary gas to provide a system pressure within a threshold range. Preferably the system is pressurised to a system pressure between 3 and 20 bar.

[0025] The auxiliary gas charge provides a uniform pressure across the system. The auxiliary gas charge can be range between 3 to 20 bar based on desired cooling temperature. In particular, the system may be pressurised to a uniform pressure, avoiding the need to maintain significant pressure differentials as required in conventional cooling systems. The auxiliary gas control valve may be configured to direct the flow of auxiliary gas within the system.

[0026] Preferably the auxiliary gas comprises an inert gas. Preferably the auxiliary gas comprises one or more of: hydrogen or a noble gas. The noble gas could be one or more of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn).

[0027] Preferably the refrigerant comprises ammonia and the auxiliary gas comprises hydrogen. These materials are particularly environmentally friendly compared to conventional refrigerants. Preferably the system is pressurised with the auxiliary gas.

[0028] Preferably the heat exchanger of each adsorbent bed comprises an electric heater arranged to heat the absorbed material to a desorption temperature at which the refrigerant is desorbed from the adsorbent material. In some examples, the electric heater may heat a fluid that is passed through pipes of the heat exchanger to heat the adsorbent material. The energy used to heat the heater may be collected from waste heat in the system.

[0029] Preferably the desorption temperature is 50 - 80°C, more preferably 70 - 80°C. In this way, only a relatively small increase in temperature is sufficient to begin desorption, reducing the energy required to heat and therefore drive the adsorption cycle.The system preferably comprises a refrigerant control valve configured to control the flow of refrigerant between each adsorption bed and the condenser and a controller configured to control the heat exchanger, refrigerant flow control valve and auxiliary gas control valve to provide a cooling cycle. In particular the controller is configured to control the heating provided by the heat exchanger of each adsorption bed and the selective connection of each adsorption bed to the condenser and evaporator to provide a continuous cooling cycle in which refrigerant is always evaporating in the evaporator and being adsorbed by the adsorbent material of an adsorption bed.

[0030] Preferably the controller is configured to perform the following sequence of steps: control a supply of heat to the heat exchanger of a first adsorption bed in which the adsorbent material is saturated with adsorbed refrigerant to raise the temperature to a desorption temperature thereby starting desorption of the refrigerant (thereby increasing a dynamic pressure in the system); operate the refrigerant control valve to permit a flow of desorbed gas phase refrigerant from the first adsorption bed to the condenser, while preventing a flow of refrigerant from the evaporator to the first adsorption bed; operate the auxiliary gas control valve to direct the auxiliary gas to a flow of liquid phase refrigerant from the condenser to the evaporator; operate the refrigerant control valve to permit a flow of the gas phase refrigerant from the evaporator to a second adsorption bed, in which the adsorption material is empty of refrigerant, (thereby reducing the dynamic pressure in the system) , while controlling the refrigerant control valve to prevent a flow of refrigerant between the evaporator and the first adsorption bed. In this way continuous cooling is provided to a target area at the evaporator.

[0031] Preferably the system is configured to provide cooling for the battery of an electric vehicle. In particular, the evaporator is arranged adjacent to the battery of the electric vehicle.

[0032] Preferably the previously defined components form an adsorption-based cooling subsystem the cooling system further comprising a vapour-compression cooling subsystem, the system further comprising a controller configured to switch between the adsorption-based cooling subsystem and the vapour-compressioncooling subsystem. In particular, the adsorption-based cooling subsystem (or “cooling module”) may comprise the one or more adsorption beds, the condenser, the evaporator and the auxiliary gas control valve.

[0033] In some examples the controller is configured to determine the temperature of the battery and switch between the cooling subsystems depending on the rate of cooling required. The system may comprise one or more sensors for measuring a temperature of the system or an object to be cooled, wherein the controller is configured to control the system in response to the sensor data. In some examples the controller is configured to control the adsorption-based cooling subsystem to provide continuous cooling and use the vapour-compression subsystem (or a Peltier cooling subsystem) when there is a spike in cooling demand, for example when an increase in temperature is measured requiring increased cooling for a restricted period of time.

[0034] The system may comprise a heat recovery unit arranged to recover waste heat and transfer the heat energy to the heat exchanger of the one or more adsorption beds to at least partially drive the heating of the adsorbent material. In some examples the heat exchanger comprises a heat pipe. In this way, waste heat may be efficiently applied to heat the adsorbent material, requiring a relatively short heating time.

[0035] In a further aspect of the invention there is provided an electric vehicle comprising the cooling system of any preceding clause or appended claim. Preferably the electric vehicle comprises a battery, wherein the evaporator is arranged to cool the battery during use. In particular the evaporator may be positioned adjacent to part of the battery. In this way, the benefits of the cooling system in terms of reduced weight, complexity and energy requirement are realised to provide improvements to an electric vehicle.

[0036] Preferably the evaporator of the cooling system comprises a serpentine pipe extending around components of the electric vehicle to be cooled. In this way the evaporator can extend to cool multiple dispersed regions of the electric vehicle.Preferably the evaporator comprises one or more plates arranged in direct contact with components of the electric vehicle to be cooled. Preferably the electric vehicle comprises an adsorption based cooling system comprising the system according to any appended claim or preceding clause; a vapour compression cooling system; and a controller configured to selectively operate the adsorption based cooling system and the vapour compression cooling system.

[0037] Preferably the controller is configured to determine a required rate of cooling and switch between using the adsorption based cooling system to using the vapour compression based cooling system when the required rate of cooling exceeds a threshold.

[0038] In a further aspect of the invention there is provided a method of cooling using a cooling system comprising one or more adsorption beds, each absorption bed comprising adsorbent material for adsorbing a refrigerant and a heat exchanger for heating the adsorbent material to facilitate desorption of the refrigerant, the method comprising the steps: controlling a supply of heat to the heat exchanger of a first adsorption bed, where the adsorbent material of the first adsorption bed comprises an adsorbed refrigerant, thereby raising the temperature to a desorption temperature to start desorption of the refrigerant; operating a refrigerant control valve to permit a flow of desorbed gas phase refrigerant from the first adsorption bed to a condenser, the condenser arranged to condense a desorbed refrigerant vapour received from an adsorption bed into its liquid phase, the condenser connected to an evaporator, the evaporator arranged to receive a liquid phase refrigerant from the condenser and evaporate the refrigerant, thereby providing cooling to a target area adjacent to the evaporator; operating an auxiliary gas control valve to provide a supply of an auxiliary gas to the evaporator to control a partial pressure of the refrigerant.

[0039] Preferably the method further comprises operating the refrigerant control valve to permit a flow of the gas phase refrigerant from the evaporator to a second adsorption bed, in which the adsorption material is empty of refrigerant, thereby reducing the pressure in the system.Preferably the method further comprises positioning the evaporator adjacent to the battery of an electric vehicle to provide cooling of the battery.

[0040] BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a schematic illustration of a cooling system according to the present invention;

[0042] Figure 2 is a flow diagram illustrating a cooling methods according to the present invention.

[0043] DETAILED DESCRIPTION

[0044] The present invention provides a thermal management solution, particularly suited to the cooling of electrical components, such as the battery, of electrical vehicles. The system implements adsorption-based cooling, using absorbent beds to drive the cooling process, with the system utilising the selective control of an inert gas to manage and adjust a partial pressure of the refrigerant within the system.

[0045] Figure 1 schematically illustrates a cooling system 100 according to the present invention. The cooling system 100 comprises one or more, in this case two, adsorption beds 110. The adsorption beds each comprise adsorbent material 111 suitable for adsorbing a refrigerant and a heat exchanger 112 suitable for transferring heat to the adsorbent material 111 to facilitate desorption of the refrigerant form the adsorbed material 111 when saturated. The system 100 further comprises a condenser 130 which is connected to the adsorption beds 110 and arranged to condense a desorbed refrigerant vapour received from an adsorption bed 110 into its liquid phase. Connected to the condenser 130 is an evaporator 140 arranged to receive the liquid phase refrigerant from the condenser 130 and evaporate the refrigerant, thereby causing cooling in a target area around the evaporator 140. The evaporator 140 is connected to the one or more adsorption beds 110 such that the evaporated refrigerant diffuses from the evaporator 140 to the connected adsorption bed 110. The system further comprises an auxiliary gas control valve 150 configured to direct a flow of auxiliary gas to the evaporator 140 to facilitate auxiliary gas flow to the evaporator, whereit mixes with the liquid refrigerant to provide evaporative cooling in the evaporator, thereby lowering the temperature required to evaporate the refrigerant, and provide evaporative cooling. This is achieved without requiring significant changes in total pressure across the system. By positioning the evaporator 140 near components to be cooled, such as the battery of an electric vehicle, cooling may be achieved through the cycle of the system 100.

[0046] Unlike conventional thermal management systems, such as those employing vapour compression technologies, the present invention has significantly reduced demand for electrical power, since the adsorption and desorption cycles can be driven by changing temperature alone, and the system does not require mechanical components such as compressors to maintain pressure differences across the system. Instead, the pressure is substantially uniform across the system, and only the temperature of the adsorption beds is controlled to drive the flow of refrigerant and evaporation and diffusion of the refrigerant to the adsorption bed 110, thereby providing cooling adjacent to the evaporator 140. The fact that the system does not require mechanical parts to maintain these pressure differences present in conventional systems significantly reduces the complexity, weight and manufacturing cost. This provides significant advantages when implementing the system in electric vehicle (EV) architectures where reductions in weight immediately benefits the range of the vehicles. Furthermore, the present invention uses natural refrigerants such as ammonia with inert gasses such as noble gasses or hydrogen providing the auxiliary gas used to facilitate the partial pressure drop of the refrigerant. Therefore, the present system is significantly more environmentally friendly than systems using harmful polluting refrigerants such as R134a and R1234yf.

[0047] Figure 1 shows a specific example of the present invention, implementing two adsorption beds 110-1, 110-2, allowing continuous cooling by implementing a reciprocal cycle in which each bed 110 alternates between an adsorption and a desorption phase. However, the system could be implemented with a single bed to provide periodic cyclical cooling, or with a greater number of adsorption beds 110. As shown in Figure 1 each adsorption bed 110 comprises an adsorbentmaterial 111 suitable for reversibly adsorbing and desorbing a refrigerant during refrigeration cycles. In the example of Figure 1 the refrigerant is ammonia which is an environmentally friendly refrigerant that also has improved thermal properties compared to conventional refrigerants. In particular ammonia has a higher latent heat of vaporisation compared to conventional refrigerants (-1370 kJ / kg at -15°C compared -215 kJ / kg for to R134a) allowing it to absorb significantly more heat during phase change. Ammonia is also usable over a broad temperature range (effective from -70°C to +80°C) and its thermal properties provide improved energy efficiency metrics, allowing it to achieve target temperatures with lower compression ratios.

[0048] The adsorbent material 111 may be any material suitable for reversible adsorbing and desorbing the selected refrigerant. The adsorbed material selected should have a high affinity for the refrigerant and preferably be suitable for applications requiring high refrigerant and storage density. The material should ideally have a high surface area / porosity, thermal stability to withstand cyclic heating and cooling without degradation, low adsorption heat thereby reducing energy input during regeneration, chemical compatibility, ideally non-corrosive and inert with ammonia, and regeneration efficiency, providing fast desorption kinetics under moderate heat. Examples of suitable materials include MOF, activated carbon, high silica zeolites, silica gel and alumina and metal chlorides (salt composites), such as zinc chloride and strontium chloride.

[0049] Each bed 110 additionally comprises a heat exchanger 112 arranged to exchange heat with the adsorbent material in the bed 110. The heat exchanger is preferably arranged to provide efficient heat transfer between the adsorbent material 111 and the heat exchanger 112. In the example of Figure 1 the heat exchanger 112 comprises an electrical heater with a plurality of longitudinal portions 115, arranged in a grid arrangement, around which the adsorbent material 111 is provided, thereby increasing the contact area between the heat exchanger 112 and adsorbent material 111. In the example of Figure 1 the heat exchanger 112 is provided by an electrical heater but in other examples, as will be described, it could be provided in other ways. For example, the heat exchanger could beconnected to an energy recovery system configured to recover energy from other electrical components in an EV and provide the recovered energy to heat a fluid that is passed along the pipes 115 of the heat exchanger 112. The adsorption beds 110 further comprise an outer housing 114 enclosing an internal volume containing the heat exchanger 112 and adsorbent material 111, wherein the refrigerant may be selectively transferred into and out of the internal volume using a system of valves, depending on the stage of the cooling cycle.

[0050] The cooling system 100 further comprises a refrigerant control valve 120 configured to control the flow of the refrigerant within the system 100 between the adsorption beds 110 and the condenser 130 and evaporator 140. In particular, the refrigerant control valve 120 is configured to place the internal volume of an adsorbent bed in fluidic communication with the condenser 130 when the adsorbent bed is in the desorption phase in which the adsorbent material 111 of the bed 110 is undergoing desorption to release the refrigerant such that the refrigerant may flow from the adsorption bed 110 to the condenser 130 through the refrigerant control valve 120. Similarly, the refrigerant control valve 120 is configured to place the internal volume of an adsorbent bed 110 in fluidic communication with the evaporator 140 when the corresponding adsorbent bed 110 is in the adsorption phase in which the non-saturated adsorbent material is adsorbing the evaporated refrigerant diffusing from the evaporator. Therefore, the refrigerant control valve allows the evaporated refrigerant to flow from the evaporator 140 through the refrigerant control valve 120 to the adsorption bed 110 during the desorption stage.

[0051] In the schematic example of Figure 1 the refrigerant control valve 120 is illustrated as a single selective flow diverter configured to selectively place each bed in communication with the evaporator or condenser depending on the phase of the cooling cycle. In practice the refrigerant control valve may be implemented in a number of different ways and by differing numbers of specific constituent valves to control the flow of refrigerant and auxiliary gas as described.

[0052] As showed in Figure 1 the system further comprises a condenser 130. The role of the condenser is to convert refrigerant vapour (in this case ammonia) back toliquid after desorption from the adsorbent bed 110. This phase change releases latent heat, which is rejected to the environment, or may be captured and used to heat the heat exchanger 112 of another adsorbent bed 110 during the desorption phase. The condenser 130 may take one of several different forms. For example, the condenser 130 may comprise an air cooled condenser, using ambient air to cool the refrigerant. An air cooled condenser may comprise a plurality of fins or tubes through which the vapour phase refrigerant passes providing increased contact with the surrounding air to promote cooling and condensing of the refrigerant. Such examples of condensers are relatively low maintenance with no cooling fluid, such as water, required but are of lower efficiency in high ambient temperatures. Alternatively, the condenser 130 may be a water-cooled condenser in which water is circulated through coils to absorb heat from the refrigerant. Water cooled condensers have higher efficiency than air cooled types but are more complex and due to the requirement for water to be circulated in the system. The condenser 130 may take any other suitable form known from the art as long as it can provide its essential function of cooling the vapour phase refrigerant received from an adsorption bed 110 to condense it into its liquid phase.

[0053] The cooling system 100 of Figure 1 further comprises an evaporator 140, which is responsible for generating the cooling effect by facilitating the evaporation of the refrigerant (in this example, ammonia) at low (partial) pressure. The evaporator 140 receives liquid refrigerant from the condenser 130 via connection S5 indicated in Figure 1. The evaporator 140 is structured to evaporate the liquid phase refrigerant thereby absorbing heat from the surrounding environment. By positioning the evaporator 140 next to the components to be cooled the evaporator provides heat exchange between those components and the refrigerant to provide cooling of the components. The evaporator 140 creates a (partial) pressure drop that drives refrigerant vapour from the evaporator 140 to a connected adsorbent bed 110 containing unsaturated adsorbent material during the adsorption phase.

[0054] The evaporator 140 may take any form known from the art suitable to facilitate transfer of ambient heat to the fluid as it evaporates. Examples of possible evaporator structures include fin-tube evaporators comprising tubes with externalfins to enhance heat transfer between the refrigerant and surrounding air. Fin tube evaporators are compact cost effective and suitable for air cooling applications. The evaporator 140 may alternatively be implemented by a shell and tube evaporator in which the refrigerant flows through tubes while chilled water circulates in the shell, providing higher heat transfer efficiency and durability under pressure fluctuations. In other examples the evaporator 140 may be a plate evaporator comprising corrugated plates creating alternating channels for refrigerant and coolant, which are particularly suited to compact systems requiring high surface area to volume ratios and they are light weight and efficient for liquid cooling applications. Another example of a potential evaporator structure is a falling film evaporator in which liquid refrigerant, such as ammonia, cascades over vertical tubes or plates evaporating as it absorbs heat. This is particularly suited to systems prioritising low refrigerant charge and high efficiency thereby providing reduced refrigerant inventory and better temperature control.

[0055] An evaporator arrangement particularly suited to the cooling of components of EVs is where the evaporator 140 comprises a serpentine pipe with one or more plates in contact with the objects to be cooled to provide direct cooling via conduction. In this way, the serpentine pipe may extend through and / or around components of the electric vehicle such as the battery and motor to reach multiple different areas for cooling. The evaporator 140 may comprise a flat plate in contact with each component to be cooled so that heat is transferred from the components through the plate to the evaporating refrigerant in the pipe of the evaporator. Once the refrigerant is evaporated it diffuses via the refrigerant flow control valve 120 to a connected adsorption bed 110 undergoing adsorption.

[0056] The evaporator might be in a hybrid set up with another electrical cooling system, such as Peltier thermoelectric cooling system, the latter usable to meet any jump in temperature demand or covering any sudden spikes in the battery temperature.

[0057] The system of Figure 1 further comprises an auxiliary gas control valve 150 for directing a supply of an auxiliary gas to the evaporator 140 to provide a continuous flow loop for the auxiliary gas, maintaining the reduced partial pressure of the refrigerant in the evaporator 140. A key contribution of the present invention isthat the use of an inert auxiliary gas, preferably hydrogen when used with an ammonia refrigerant, which can be used to facilitate the reduced partial pressure of the refrigerant. By applying an inert gas to the evaporator, it is possible to enhance the diffusion of the refrigerant to the adsorption beds 110 while maintaining a substantially uniform low pressure across the system 100. This removes the need for complex mechanical components required to pressurise the system to high pressure and maintain different portions of the system at different pressures. The auxiliary gas control valve 150, in this example a hydrogen control valve 150, selectively directs the auxiliary gas, from the auxiliary gas outlet S3 of each adsorption bed to the evaporator 140. In particular, the auxiliary gas control valve 150 is configured to connect the auxiliary gas outlet S3 of each adsorption bed to the evaporator 140 to provide a continuous supply of the auxiliary gas to the evaporator 140. In some examples the auxiliary gas control valve may simply direct auxiliary gas, separated from the refrigerant in the adsorption bed, to the evaporator 140. Providing an inert gas such as hydrogen reduces the partial pressure of the refrigerant in the evaporator enhancing the evaporation of the refrigerant (in this case ammonia) meaning the ammonia evaporates at a low temperature to provide improved cooling of the adjacent components to be cooled. The evaporated ammonia flows to a connected absorption bed containing a nonsaturated adsorbent material. In the adsorption bed the adsorbent material adsorbs the ammonia and the remaining auxiliary gas (which is rich in hydrogen or pure hydrogen) is removed and circulates back to the auxiliary gas control valve 150 via connection S3, ready to be provided again to the evaporator 140.

[0058] The provision of the auxiliary gas ensures that the refrigerant diffuses to the adsorbent bed 110 without relying on a large total pressure difference. The system can therefore operate continuously, under a substantially uniform system pressure, without a pump or compressor using only the heat supply to the adsorption beds as the driving force. This allows for silent, reliable operation ideal for application in vehicles such as electronic vehicles. Furthermore, instead of the ammonia moving due to high pressure differences it diffuses through the hydrogen rich atmosphere at near uniform total pressure. This allows continuous operation with minimal energy input. Since there is no need for a compressor or largepressure differential the system is mechanically simple and highly reliable with no moving parts except for fluid flow. The partial pressure gradient of the refrigerant is maintained by the adsorber removing the ammonia vapour in the adsorbent bed 110 and the auxiliary gas control valve 150 directing the auxiliary gas to the evaporator to ensure that the refrigerant vapour can continue to diffuse without creating large pressure imbalances. The system is preferable pressurised with the auxiliary gas to provide a system pressure between 3 and 20 bar. The system pressure may be selected depending on the cooling temperature required. The inert auxiliary gas (preferably hydrogen but possibly an inert gas such as a noble gas) is present in the portions of the system other than the condenser..

[0059] As showed in Figure 1 the system 100 comprises a plurality of connections S1, S2, S3, S4, S5, S6, S7, S8 providing fluid communication between the various components of the system 100. The refrigerant control valve 120 and the hydrogen control valve 150 control the selective connection of the various components of the system to provide the cooling cycle. The valves maybe controlled by a controller which automatically control the opening and closing the valves to provide required cooling cycle parameters. The controller may be provided by a local computer configured to control the valves according to a preset cycle. The controller may receive data from one or more sensors to dynamically adjust the cycle according to the required cooling requirements, based on real-time operational data - for example based on a measurement of the saturation of the adsorption beds 100 and / or a measurement of the temperature of the components to be cooled.

[0060] The operation of the system, and the flow of refrigerant and auxiliary gas, during an example cooling cycle will now be described. As described above, in this example the system comprises two adsorption beds bed 1 110-1 and bed 2 110-2. Beds 1 and 2 alternate between adsorption and desorption such that bed 1 is undergoing desorption while bed 2 is undergoing adsorption and vice versa. To illustrate the cycle, at a starting point bed 1 is currently saturated with the adsorbent material containing adsorbed ammonia. Heat is then applied to bed one 110 via the heat exchanger 112, for example using an electric heating controlsystem which may heat the adsorbent material directly or heat a fluid such as water which passes between the various pipes 115 of the heat exchanger 112. In this example, the bed is heated to a desorption temperature of between 50°C and 80°C. This causes the ammonia to desorb, transitioning into the gas phase and leaving bed one 110 via connection S1. The desorbed ammonia then moves through the ammonia flow control valve 120 to connection S4 connecting the refrigerant control valve 120 to the condenser 130. In the condenser 130, the ammonia releases heat, either through a fan or via ambient air flow, until its temperature drops to around 30°C (this temperature should be at the subcooling condition of ammonia at the system pressure). Once condensed, the ammonia becomes a liquid and may undergo further sub cooling before exiting the condenser 130 into connection S5, which connects the condenser to the evaporator 140.

[0061] At the evaporator inlet S7 the auxiliary gas, in this case hydrogen, is introduced into the ammonia flow stream from the hydrogen control valve through connection S6. Inside the evaporator 140 the liquid ammonia comes into contact with the hydrogen and, due to a partial pressure drop, the ammonia begins to evaporate, preferably reducing its temperature to a range between -33°C and 25°C, depending on the specific parameters of the systems design (such as the specific selected “charging pressure” or system pressure, usually between 3 and 20 bar) and the desired cooling temperature. This phase change from liquid to gas requires energy which is adsorbed from the surroundings providing the cooling effect. The evaporator 140 then transfers heat from the objects requiring cooling, for example the battery of an electric vehicle, thereby lowering their temperature.

[0062] The ammonia hydrogen gas mixture exits the evaporator 140 at the outlet S8, where the temperature matches the target cooling temperature. For example, if a cooling temperature of 5°C is needed, the evaporator outlet will also be at 5°C. The gas mixture flows through the ammonia flow control valve 120 before reaching bed two 110-2 and entering through inlet S2. Bed two 110-2 contains a nonsaturated (i.e. empty) adsorbent material 111, which captures the gaseous ammonia separating it from the hydrogen. The separated hydrogen thenrecirculates back to the evaporator through connection S3. Once the adsorbent material 111 of bed two 110-2 is saturated, the cycle reverses. Heat is then provided to the heat exchanger 112 of bed two 110-2 such that the adsorbent material 111 of bed two 110-2 begins desorbing ammonia, which then flows from bed two to the condenser 130. Meanwhile evaporated refrigerant from the evaporator 140 flows from the evaporator 140 to bed one 110-1 in which the adsorbent material 111 is empty and ready to adsorb the refrigerant to complete the cycle. This alternating process ensures continuous cooling may be provided.

[0063] Figure 2 displays a flow diagram showing a method according to the present invention. In particular, the method comprises a first step of controlling a supply of heat to the heat exchanger of a first adsorption bed where the adsorbent material of the first adsorption bed comprises an adsorbed refrigerant, thereby raising the temperature to a desorption temperature to start desorption of the refrigerant. The method continues to a second step 202 comprising operating a refrigerant control valve to permit a flow of desorbed gas phase refrigerant from the first adsorption bed to a condenser, the condenser arranged to condense a desorbed refrigerant vapour received from an adsorption bed into its liquid phase, the condenser is connected to an evaporator, the evaporator arranged to receive a liquid phase refrigerant from the condenser and evaporate the refrigerant thereby providing cooling to a target area adjacent to the evaporator. The method 200 of Figure 2 involves a final step of operating an auxiliary gas control valve to provide a supply of an auxiliary gas to the evaporator to facilitate a partial pressure drop of the refrigerant.

[0064] Alternative features and implementations

[0065] The above described system may be adapted in several different ways for differing applications to address varying operational requirements and vehicle architectures. These alternatives provide flexibility in deployment while maintaining the core objective of enhancing battery cooling efficiency in electric vehicles.The adsorption based cooling system of the present invention may be implemented within a hybrid adsorption-compression system: This implementation combines adsorption cooling with conventional vapourcompression refrigeration technology. By utilising adsorption cooling during low-demand periods and switching to a compression-based system when rapid cooling is required, this hybrid approach offers a balance between energy efficiency and performance. In particular the system may comprise an adsorption cooling module and a compression cooling module with a controller configured to selective operate the modules according to requirements. For example, the controller may receive data from one or more sensors to determine the rate of cooling required and use the compression cooling module when the rate of cooling exceeds a threshold. This allows a rapid response to sudden thermal spikes, optimal energy utilisation under varying load conditions and compatibility with existing vehicle HVAC systems. This kind of hybrid system would preferably be employed in high-performance electric buses and long-haul commercial vehicles with fluctuating cooling demands.

[0066] In another example the cooling system can comprise a hybrid system comprising an adsorption based cooling module and a Peltier cooling module. The adsorption system may then provide steady cooling and the Peltier system can be operated to cover any spikes in cooling demand, for example due to an increase in temperature. A control unit may be configured to monitor the required cooling demand, for example using one or more temperature sensors, and operate the Peltier cooling module when there is a spike in temperature and an increased rate of cooling is required.

[0067] In another possible implementation the system may implement a passive cooling configuration. In this example, the system leverages ambient air and passive heat exchange methods, such as phase change materials (PCMs), in combination with adsorption cooling to provide a low-maintenance, energy-efficient solution. Again the system may comprise a controller configured to selectively operate an adsorption cooling system and a passive heat exchange module according to the cooling demands. The advantages of such an implementation is that it eliminatesthe need for active components, reducing maintenance and operational complexity, and providing lower manufacturing costs and simplified installation. Such a system is ideal for moderate climate conditions where extreme thermal fluctuations are minimal and is preferably employed in small to medium-sized electric vehicles operating in mild climatic regions.

[0068] The above described system preferably employs a single circuit to provide cooling across the components of an electric vehicle. However, instead of a centralised cooling system, an alternative implementation deploys multiple smaller, modular cooling units distributed across different sections of the vehicle. Each unit operates independently, targeting specific components such as high-density battery clusters or power electronics. This provides enhanced thermal management precision for critical components, improved redundancy and fault tolerance, as each module operates independently and it allows the system to be readily scalable to accommodate various vehicle sizes and configurations. A preferred use case is large fleet operations where customisation and modularity are key to operational efficiency.

[0069] As described above the heating of the adsorbent material may be achieved in a number of different ways. In one example the cooling system is integrated with waste heat recovery systems. Such a system leverages waste heat from the vehicle's powertrain (where applicable) to drive the adsorption cooling cycle, maximising energy utilisation and improving system sustainability. The advatange of such an approach is that it increases overall vehicle energy efficiency by repurposing waste heat, it reduces dependency on external power sources for cooling operations and it aligns with circular energy concepts in sustainable vehicle design. A preferred use case is plug-in hybrid electric vehicles (PHEVs) and fuel cell electric vehicles (FCEVs) with available heat sources.

[0070] While the cooling system described herein is particularly preferably implemented in electric vehicles, the present invention has a wide range of potential applications across various industries that require efficient, sustainable, and low-energy cooling solutions. The core technology can be adapted with minimal modifications to serve the following sectors:Renewable energy storage systems

[0071] Battery energy storage systems (BESS) used in solar and wind energy installations require efficient thermal management to maintain battery health and extend lifespan. The present invention can provide passive and active cooling solutions to prevent overheating in large-scale battery installations. This application requires a larger system scaling for stationary applications and could also integrate with existing energy management systems.

[0072] Data centres and IT infrastructure

[0073] The growing demand for data processing and cloud services requires advanced cooling systems to manage heat dissipation from high-performance servers. The invention can be applied to data centres to offer energy-efficient and environmentally friendly cooling solutions. In such an implementation the system can be provided as modular cooling units configured to fit server racks. It can further be integrated with existing HVAC infrastructure in data centers.

[0074] Cold chain logistics and refrigeration

[0075] The food and pharmaceutical industries rely on refrigerated transport and storage for perishable goods. The present invention can be used to maintain precise temperature control with reduced energy consumption, especially for last-mile electric delivery vehicles. It can be readily customised for temperature-specific storage needs and adaptation for mobile refrigeration units.

[0076] Aerospace and aviation

[0077] Aircraft and space applications require highly efficient thermal management for battery and electronic systems. The adsorption cooling technology of the present invention offers a lightweight, low-power alternative to conventional cooling methods in aviation and space missions.

[0078] Smart buildings and HVAC systemsThe present invention can be integrated into smart building systems for efficient climate control, reducing reliance on conventional HVAC systems while improving sustainability in commercial and residential properties. The system can be implemented with existing building automation systems.

[0079] Healthcare and medical equipment cooling

[0080] Critical medical equipment such as MRI machines, diagnostic scanners, and vaccine storage units require precise thermal regulation. The present adsorption based cooling system can help maintain operational stability and prolong equipment lifespan. Its compact design makes it well suited for medical device integration.

Claims

CLAIMS1. A cooling system comprising:one or more adsorption beds, each comprising adsorbent material for adsorbing a refrigerant and a heat exchanger for heating the adsorbent material to facilitate desorption of the refrigerant;a condenser connected to the one or more adsorption beds and arranged to condense a desorbed refrigerant vapour received from an adsorption bed into its liquid phase;an evaporator arranged to receive a liquid phase refrigerant from the condenser and evaporate the refrigerant causing cooling in a target area adjacent to the evaporator, wherein the evaporator is connected to the one or more adsorption beds such that a vapour phase refrigerant diffuses from the evaporator to a connected adsorption bed;the system characterised in that the system further comprises an auxiliary gas control valve for directing a flow of an auxiliary gas to the evaporator to reduce a partial pressure of the refrigerant.

2. The system of claim 1 comprising:a first adsorption bed and a second adsorption bed, wherein the first and second adsorption bed are each connected to both the condenser and evaporator;wherein the system is configured to operate a reciprocal cycle in which one adsorption bed is undergoing desorption in which the refrigerant is desorbed from the absorbent material and flows to the condenser, while the other adsorption bed is undergoing adsorption in which the refrigerant is received from the evaporator and is adsorbed onto the adsorbent material.

3. The system of claim 2 further comprising a refrigerant control valve configured to control the flow of refrigerant between each adsorption bed and the condenser and evaporator.

4. The system of claim 3 wherein the refrigerant control valve is configured to control the flow of refrigerant for each adsorption bed to provide:a flow of desorbed refrigerant from the adsorption bed to the condenser when the adsorption bed is undergoing desorption; anda flow of evaporated refrigerant from the evaporator to the adsorption bed when the adsorption bed is undergoing adsorption.

5. The system of any preceding claim wherein the auxiliary gas control valve is configured to provide a flow of the auxiliary gas to the evaporator to reduce the partial pressure of the refrigerant in the evaporator.

6. The system of any preceding claim wherein the auxiliary gas control valve is configured to provide a flow of the auxiliary gas to the evaporator to provide a partial pressure gradient between the evaporator and a connected adsorption bed, where the adsorbent material of the connected adsorption bed is non-saturated, to increase diffusion of the refrigerant from evaporator to the connected adsorption bed.

7. The system of any preceding claim wherein the system is pressurised with the auxiliary gas to provide a system pressure within a threshold range.

8. The system of any preceding claim wherein the system pressure is between 3 and 20 bar.

9. The system of any preceding claim wherein the auxiliary gas comprises an inert gas.

10. The system of any preceding claim, wherein the refrigerant comprises ammonia and the auxiliary gas comprises a noble gas or hydrogen.

11. The system of any preceding claim wherein the heat exchanger is configured to heat the adsorbent material to a desorption temperature, wherein the desorption temperature is between 50 - 80°C12. The system of any preceding claim in which the system comprises a refrigerant control valve configured to control the flow of refrigerant between each adsorption bed and the condenser and a controller configured to control the heatexchanger, refrigerant flow control valve and auxiliary gas control valve to provide a cooling cycle.

13. The system of claim 12 wherein the controller is configured to perform the following sequence of steps:control a supply of heat to the heat exchanger of a first adsorption bed in which the adsorbent material is saturated with adsorbed refrigerant to raise the temperature to a desorption temperature thereby starting desorption of the refrigerant;operate the refrigerant control valve to permit a flow of desorbed gas phase refrigerant from the first adsorption bed to the condenser, while preventing a flow of refrigerant from the evaporator to the first adsorption bed;operate the auxiliary gas control valve to direct the auxiliary gas to a flow of liquid phase refrigerant from the condenser to the evaporator;operate the refrigerant control valve to permit a flow of the gas phase refrigerant from the evaporator to a second adsorption bed, in which the adsorption material is empty of refrigerant, while controlling the refrigerant control valve to prevent a flow of refrigerant between the evaporator and the first adsorption bed.

14. The system of any preceding claim configured to provide cooling for the battery of an electric vehicle.

15. The system of claim 14 wherein the components defined in any preceding claim form an adsorption-based cooling subsystem the cooling system further comprising a vapour-compression cooling subsystem, the system further comprising a controller configured to switch between the adsorption-based cooling subsystem and the vapour-compression cooling subsystem.

16. The system of claim 15 wherein the controller is configured to determine the temperature of the battery and switch between the cooling subsystems depending on the rate of cooling required.

17. The system of any of claims 14 to 16 further comprising a heat recovery unit arranged to recover waste heat and transfer the heat energy to the heatexchanger of the one or more adsorption beds to at least partially drive the heating of the adsorbent material.

18. An electric vehicle comprising the cooling system of any preceding claim.

19. The electric vehicle of claim 18 comprising a battery, wherein the evaporator is arranged to cool the battery during use.

20. The electric vehicle of claim 18 or claim 19 wherein the evaporator of the cooling system comprises a serpentine pipe extending around components of the electric vehicle to be cooled.

21. The electric vehicle of claim 20 wherein the evaporator comprises one or more plates arranged in direct contact with components of the electric vehicle to be cooled.

22. The electric vehicle of any of claims 18 to 21 comprising:an adsorption based cooling system comprising the system according to any of claims 1 to 17;a vapour compression cooling system;a controller configured to selectively operate the adsorption based cooling system and the vapour compression cooling system.

23. The electric vehicle of claim 22 wherein the controller is configured to determine a required rate of cooling and switch between using the adsorption based cooling system to using the vapour compression based cooling system when the required rate of cooling exceeds a threshold.

24. A method of cooling using a cooling system comprising one or more adsorption beds, each absorption bed comprising adsorbent material for adsorbing a refrigerant and a heat exchanger for heating the adsorbent material to facilitate desorption of the refrigerant, the method comprising the steps:controlling a supply of heat to the heat exchanger of a first adsorption bed, where the adsorbent material of the first adsorption bed comprises an adsorbed refrigerant, thereby raising the temperature to a desorption temperature to start desorption of the refrigerant;operating a refrigerant control valve to permit a flow of desorbed gas phase refrigerant from the first adsorption bed to a condenser, the condenser arranged to condense a desorbed refrigerant vapour received from an adsorption bed into its liquid phase, the condenser connected to an evaporator, the evaporator arranged to receive a liquid phase refrigerant from the condenser and evaporate the refrigerant, thereby providing cooling to a target area adjacent to the evaporator;operating an auxiliary gas control valve to direct a supply of an auxiliary gas to the evaporator to reduce a partial pressure of the refrigerant.

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