Phase change material, heat exchanger and related thermal battery

Abstract

The phase change temperature range of the phase change material (PCM) provided by the invention is about 3 DEG C to 27 DEG C. The PCM comprises 35% to 60% (by weight) of at least one inorganic salt, 1% to 9% (by weight) of at least one nucleating agent, 1% to 4% (by weight) of at least one thickening agent, and generally 30% to 66% (by weight) of moisture. The PCM can be used in a thermal battery (1) comprising a tank (2) for containing the PCM. The thermal cell (1) comprises a HEX 4 having a plurality of plates (5), each plate (5) forming a fluid flow channel (7) extending through the plate. The plates (5) are arranged in the storage tank (2) in a regular array, so that the fluid flow channels (7) of each plate (5) are arranged in a staggered mode in the storage tank (2) relative to the adjacent plates.

Description

Technical Field

[0001] This invention relates to the design and manufacture of thermal batteries, including the formulation design of phase change materials (PCMs) and the structural design of heat exchangers (HEXs). This invention can be applied to, but is not limited to, heating, ventilation, and air conditioning (HVAC) systems. Background Technology

[0002] Any documents, actions, materials, devices, articles, or similar content mentioned in this specification are for illustrative purposes only and are intended to provide background information to illustrate the invention. This should not be construed as an admission that any or all of the foregoing constitutes a prior art basis existing in the relevant field of the invention in Australia or elsewhere prior to the priority date of this application, nor should it be considered an admission that it is common general knowledge in that field.

[0003] Researchers have studied phase change materials (PCMs) that melt / solidify within different temperature ranges to determine suitable formulations. However, the inventors recognize that the correct proportions of the component chemicals used to formulate PCMs are crucial for achieving the desired phase change temperature and latent heat. Furthermore, for hydrate PCMs, determining suitable additives and their proportions to address defects such as supercooling and phase separation is particularly challenging. The inventors believe that developing new formulations that combine ideal thermal, physical, chemical, stability, environmental, and / or economic properties to meet specific application requirements will be of great significance.

[0004] Typically, existing heat exchangers (HEXs) are designed to facilitate heat transfer between stationary and flowing fluids with significant temperature differences, thereby optimizing the heat transfer process. The inventors recognize the importance of developing HEXs suitable for a variety of scenarios—such as applications in thermal batteries, which involve heat transfer processes triggered by latent heat generated by liquid-solid phase changes. In particular, there is a need to develop HEXs that enable rapid discharge and allow for controllable thermal charge / discharge rates. Summary of the Invention

[0005] The purpose of this invention is to overcome or significantly improve one or more defects of the prior art, or to provide a useful alternative.

[0006] One aspect of the present invention provides a phase change material (PCM) with a phase change temperature of about 3°C ​​to 26°C, the PCM comprising: 35% to 60% (by weight) of an inorganic salt; 1% to 9% (by weight) of a nucleating agent; 1% to 4% (by weight) of a thickener; and 30% to 66% (by weight) of water.

[0007] According to a second aspect of the invention, a heat exchanger (HEX) is provided, comprising: a plurality of plates, each plate defining at least one fluid flow channel extending through the plate for the flow of a heat transfer fluid; the plurality of plates being arranged in a regular array and spaced apart from each other to define a volume for accommodating a PCM between adjacent plates; wherein, when arranged in a regular array, a first flow channel extending through a first plate is offset relative to a second flow channel extending through a second plate adjacent to the first plate.

[0008] Preferably, the fluid channel is configured such that, during use, when the heat transfer fluid flows through the fluid channel at a target operating flow rate, the Reynolds number of the turbulence generated by the heat transfer fluid is between 4000 and 7500.

[0009] According to another aspect of the present invention, a thermal battery is provided, comprising: a storage tank; a HEX housed within the storage tank; and a PCM housed within the storage tank for heat exchange with the HEX.

[0010] Preferably, the PCM used in the thermal battery is as described above.

[0011] Alternatively, the PCM can be prepared according to the method described above.

[0012] In one embodiment of the thermal battery, the HEX is as described above.

[0013] The features and advantages of the present invention will become even more apparent from the following detailed description of preferred embodiments (by way of example only) and the accompanying drawings. Attached Figure Description

[0014] Figure 1 This is a graph showing the relationship between energy storage and temperature in the first embodiment of the PCM; Figure 2 This is a graph showing the relationship between energy storage and temperature in the second embodiment of the PCM; Figure 3 This is a graph showing the relationship between energy storage and temperature in the third embodiment of the PCM; Figure 4 This is an isometric view according to a HEX embodiment of one aspect of the present invention; Figure 5 yes Figure 4 Isometric view of the plate embodiment used in HEX; Figure 6 yes Figure 5 The front view of the plate shown includes some example dimensions (unit: mm). Figure 7 yes Figure 5 The plan view of the plate shown includes some example dimensions (unit: mm); Figure 8 yes Figure 7 A plan view of the marked area B, a close-up view of the air inlet of the display panel, including some example dimensions (unit: mm); Figure 9 yes Figure 5 The right-side view of the plate shown includes some example dimensions (unit: mm); Figure 10 This is a cross-sectional schematic diagram of a thermal battery with HEX inside, sampled along the horizontal centerline of the thermal battery, which is perpendicular to each plate, and includes some example dimensions (unit: mm). Figure 11 From Figure 10 The enlarged view extracted from the image shows the horizontal cross-section of the fluid flow channel of a portion of the plate in more detail, including some example dimensions (unit: mm). Figure 12 This is an isometric cross-sectional view of the plate, taken along the horizontal centerline of the plate; Figure 13 This is an isometric view of an embodiment of a storage tank as part of a thermal battery, which is configured to house a PCM and a HEX in another embodiment. Figure 14 This is an isometric view of another embodiment of a storage tank as part of a thermal battery, the tank being prepared to receive... Figures 4 to 12 The HEX and PCM shown; Figure 15 Is adopted Figure 14 The isometric view of the thermal battery embodiment of the tank shown, with the HEX installed inside and uncovered; Figure 16 Is with Figure 15 An isometric view of the same thermal cell, but revealing hidden details; Figure 17 This is a simulation result diagram of a thermal battery embodiment using ISO+5 PCM according to one aspect of the present invention, showing the relationship between the change of outlet water temperature and the change of PCM melting fraction over time (water mass flow rate = 2400 kg / h, inlet water temperature = 15°C, ISO+5 initial temperature = -3°C). Figure 18 This is a simulation result graph showing the power release rate over time in a thermal battery embodiment using ISO+5 PCM (water mass flow rate = 2400 kg / h, inlet water temperature = 15℃, ISO+5 initial temperature = -3℃). Figure 19This is a simulation result diagram of a thermal battery embodiment using ISO+12 PCM according to one aspect of the present invention, showing the relationship between the change of outlet water temperature over time and the change of PCM melting fraction over time (water mass flow rate = 2400 kg / h, inlet water temperature = 22°C, ISO+12 initial temperature = 3°C). Figure 20 This is a simulation result graph showing the power release rate over time in a thermal battery embodiment using ISO+12 PCM (water mass flow rate = 2400 kg / h, inlet water temperature = 22℃, ISO+12 initial temperature = 3℃). Figure 21 This is a simulation result diagram of a thermal battery embodiment using ISO+25 PCM according to one aspect of the present invention, showing the relationship between the change of outlet water temperature over time and the change of phase change material melting fraction over time (water mass flow rate = 2400 kg / h, inlet water temperature = 35°C, ISO+25 initial temperature = 17°C). Figure 22 This is a simulation result of the power release rate changing over time in a thermal battery embodiment using ISO+25 PCM (water mass flow rate = 2400 kg / h, inlet water temperature = 35°C, ISO+25 initial temperature = 17°C). Detailed Implementation

[0015] Specific embodiments of the phase change material (PCM) may have a phase change temperature range of about 3°C ​​to about 27°C. Typically, at least one inorganic salt accounts for 35% to 60% of the total weight of the PCM. At least one nucleating agent accounts for 1% to 9% of the total weight of the PCM. At least one thickener accounts for 1% to 4% of the total weight of the PCM. Typically, water accounts for 30% to 66% of the total weight of the PCM.

[0016] A preferred formulation of the phase change material (PCM) has a phase change temperature of about 3°C ​​to about 6°C. The PCM formulation comprises 51% to 60% (by weight) of an inorganic salt, including 38% to 43% (by weight) of dipotassium hydrogen phosphate and 13% to 17% (by weight) of potassium fluoride. A nucleating agent comprises 3% to 9% (by weight) of the PCM formulation, including 1% to 3% (by weight) of dicalcium phosphate, 1% to 3% (by weight) of alumina, and 1% to 3% (by weight) of sodium chloride. The PCM formulation also comprises 1% to 4% (by weight) of a thickener, preferably a superabsorbent polymer (such as sodium polyacrylate and / or carbomer). Finally, the PCM formulation contains about 30% to 40% (by weight) of water.

[0017] The preferred embodiment of the phase change material (PCM) described in this invention, referred to as ISO+5, has a phase change temperature of approximately 4°C to 5°C. Figure 1The energy storage-temperature curve of this embodiment is shown. Dipotassium hydrogen phosphate comprises approximately 40.3% (preferably 40.33%) of the total weight of ISO+5, and potassium fluoride comprises approximately 15.0% (preferably 14.95%) of the total weight of ISO+5. Dicalcium phosphate comprises approximately 2.3% (preferably 2.26%) of the total weight of ISO+5. Alumina comprises approximately 2.3% (preferably 2.26%) of the total weight of ISO+5. Sodium chloride comprises approximately 2.3% (preferably 2.26%) of the total weight of ISO+5. This ISO+5 formulation contains approximately 2.7% (preferably 2.71%) (by weight) sodium polyacrylate and / or carbomer. Finally, this ISO+5 formulation contains 35.2% (preferably 35.22%) (by weight) water.

[0018] Tests conducted using thermal cycling testing equipment and differential scanning calorimetry (DSC) show that the formulation of this ISO+5 embodiment has the following characteristics: ●The phase transition temperature range is approximately 4°C to 5°C; ●Latent heat value is at least approximately 190 kJ / kg to 200 kJ / kg; ●The solid-state thermal conductivity is not less than approximately 0.9 W / m·K, specifically 1.0 W / m·K; ● The thermal conductivity of the liquid phase is not less than approximately 0.5 W / m·K, and more specifically 0.52 W / m·K; ●The solid phase heat capacity is at least about 1.4 kJ / kg·K, more specifically 1.5 kJ / kg·K; ●The liquid phase heat capacity is at least about 2.0 kJ / kg·K, more specifically 2.1 kJ / kg·K; ●The solid density is at least approximately 1700 kg / m³ 3 More specifically, 1750 kg / m 3 ;as well as ● The liquid phase density is at least approximately 1600 kg / m³ 3 More specifically, 1650 kg / m 3 .

[0019] Another preferred phase change material (PCM) formulation has a phase change temperature of about 9°C to about 13°C. This PCM formulation contains 48% to 58% (by weight) of an inorganic salt, of which 30% to 36% (by weight) is sodium sulfate and 18% to 22% (by weight) is ammonium chloride. In this PCM formulation, a nucleating agent present in the form of sodium tetraborate accounts for 1% to 3% (by weight). The PCM formulation also contains 1% to 3% (by weight) of a thickener, preferably a superabsorbent polymer (such as sodium polyacrylate and / or carbomer) in a preferred embodiment. Finally, the PCM formulation contains about 40% to 45% (by weight) of water.

[0020] The preferred embodiment of the phase change material (PCM) described in this invention, referred to as ISO+12, has a phase change temperature range of approximately 10°C to 12°C. Figure 2 The energy storage-temperature curve of this embodiment is shown. Sodium sulfate accounts for approximately 33.6% (preferably 33.61%) by mass in ISO+12. Ammonium chloride accounts for 19.8% (preferably 19.80%) by mass in ISO+12. Sodium tetraborate accounts for approximately 2.0% (preferably 1.98%) by mass in ISO+12. This ISO+12 formulation contains approximately 2.0% (preferably 1.98%) (by weight) sodium polyacrylate and / or carbomer. Finally, this ISO+12 formulation contains 42.6% (preferably 42.62%) (by weight) water.

[0021] Tests conducted using thermal cycling testing equipment and differential scanning calorimetry (DSC) showed that the formulation of this ISO+12 embodiment possesses the following characteristics: ●The phase transition temperature range is approximately 10°C to 12°C; ●Latent heat value is at least approximately 160 kJ / kg to 170 kJ / kg; ●The solid-state thermal conductivity is at least about 1.0 W / m·K, and more specifically 1.05 W / m·K; ● The thermal conductivity of the liquid phase is at least about 0.5 W / m·K, and more specifically 0.54 W / m·K; ●The solid phase heat capacity is at least about 1.4 kJ / kg·K, more specifically 1.5 kJ / kg·K; ●The liquid phase heat capacity is at least about 2.0 kJ / kg·K, more specifically 2.1 kJ / kg·K; ●The solid density is at least approximately 1500 kg / m³ 3 More specifically, 1550 kg / m 3 ;as well as ● The liquid phase density is at least approximately 1400 kg / m³ 3 More specifically, 1450 kg / m 3 .

[0022] Another preferred phase change material (PCM) formulation has a phase change temperature of about 23°C to about 27°C. This PCM formulation contains 35% to 43% (by weight) of an inorganic salt, comprising 20% ​​to 24% (by weight) of disodium phosphate and 15% to 19% (by weight) of sodium carbonate. In this PCM formulation, a nucleating agent present in the form of sodium tetraborate accounts for 1% to 3% (by weight). The PCM formulation also contains 1% to 3% (by weight) of a thickener, preferably a superabsorbent polymer (such as sodium polyacrylate and / or carbomer) in a preferred embodiment. Finally, the PCM formulation contains approximately 57% to 66% (by weight) of water.

[0023] The preferred embodiment of the phase change material (PCM) described in this invention, referred to as ISO+25, has a phase change temperature range of approximately 24°C to 26°C. Figure 3 The energy storage-temperature profile of this embodiment is shown. Sodium sulfate comprises approximately 21.8% (preferably 21.80%) of the total weight of ISO+25. Sodium carbonate comprises 16.7% (preferably 16.67%) of the total weight of ISO+25. Sodium tetraborate comprises approximately 2.0% (preferably 2.00%) of the total weight of ISO+25. The ISO+25 formulation also contains approximately 2.0% (preferably 2.00%) (by weight) sodium polyacrylate and / or carbomer. Finally, the water content in the ISO+25 formulation is 61.5% (preferably 61.53%) (by weight).

[0024] Tests conducted using thermal cycling testing equipment and differential scanning calorimetry (DSC) showed that the ISO+25 embodiment of this formulation possesses the following characteristics: ●The phase transition temperature range is approximately 24°C to 26°C; ●Latent heat value is at least approximately 190 kJ / kg to 200 kJ / kg; ●The solid-state thermal conductivity is at least about 1.0 W / m·K, and more specifically 1.04 W / m·K; ● The thermal conductivity of the liquid phase is at least about 0.5 W / m·K, and more specifically 0.52 W / m·K; ●The solid phase heat capacity is at least about 1.4 kJ / kg·K, more specifically 1.5 kJ / kg·K; ●The liquid phase heat capacity is at least about 2.0 kJ / kg·K, more specifically 2.1 kJ / kg·K; ●The solid density is at least approximately 1500 kg / m³ 3 More specifically, 1550 kg / m 3 ;as well as ● The liquid phase density is at least approximately 1400 kg / m³ 3 More specifically, 1450 kg / m 3 .

[0025] Those skilled in the art will understand that certain embodiments of the present invention provide phase change materials (PCMs) with high latent heat capacity per unit volume or mass. In practical applications, this helps to minimize the size of heat storage systems employing these PCMs embodiments. Some embodiments exhibit high thermal conductivity in both the solid and liquid phases, thereby enabling heat transfer to or dissipation from the PCMs at an ideal rate during phase change. Specifically, some embodiments have higher thermal conductivity and density compared to most prior art organic PCMs, while possessing a narrow and well-defined melting temperature range. Some embodiments exhibit small phase change volume changes at typical operating temperatures, reducing requirements for mechanical stability and PCM storage volume. Some embodiments also exhibit good phase stability, thereby simplifying heat storage setups. Some embodiments also exhibit eutectic melting (i.e., in this context, "eutectic" refers to a state where there are no significant changes in composition, enthalpy, or phase change temperature and no phase separation during repeated phase changes), which helps ensure that the PCM consistently provides reliable and predictable performance and excellent long-term stability throughout its expected service life. Therefore, some embodiments avoid the low latent heat and phase separation problems observed in certain inorganic PCMs operating within this temperature range in the prior art. Some embodiments also exhibit high density characteristics, contributing to a reduction in the overall size of the heat storage system employing the PCM. Some embodiments also exhibit extremely low subcooling. For enhanced safety, some PCM embodiments are non-toxic, non-flammable, non-corrosive, and non-explosive. Notably, some embodiments have a low-cost advantage because their raw materials are readily available commercially at reasonable prices.

[0026] The inventors believe that the superior properties described above give certain embodiments of this phase change material (PCM) the potential to surpass existing PCMs. These advantageous properties also make certain embodiments of this PCM ideal candidates for various thermal energy storage applications requiring precise temperature control. Potential new thermal energy storage applications that PCM embodiments may open up include: temperature-controlled transportation and storage of temperature-sensitive products, such as medical devices, pharmaceuticals, vaccines, and biological products. Other potential applications include temperature control during the storage and transportation of food and beverages, particularly suitable for products requiring specific temperature ranges to maintain quality and safety. Thermal energy storage applications in the building sector can regulate indoor temperatures, improve energy efficiency, and reduce the heating and cooling load on air conditioning systems. Temperature-controlled packaging technology is also suitable for products requiring constant temperature during transportation, such as blood samples or medical devices. In the medical field, cooling vests or blankets can be developed for use in postoperative recovery, fever reduction, and emergency medical scenarios.

[0027] like Figure 15 and 16The illustrated thermal battery 1 includes a tank 2 configured to contain a phase change material (PCM). In some embodiments, the PCM used within the thermal battery 1 is selected from the materials described above. The tank 2 is made of a material of suitable strength and impermeable to liquid. Specifically, in some embodiments, the tank 2 is made of stainless steel (such as SS304), while in other embodiments it is made of materials such as thermoplastic polymers (such as polypropylene). In some embodiments, the tank 2 also includes an insulating outer casing (not shown) surrounding it. Figure 13 The embodiment of the storage tank 2 shown is provided with an external support member 3 to resist the outward mechanical stress generated by the PCM inside the storage tank 2.

[0028] In one embodiment, the thermal battery 1 is sized to fit through a standard doorway. This allows the embodiment of the thermal battery 1 to be easily transported into a conventional air-conditioned room.

[0029] The storage tank 2 also houses a heat exchanger 4. In some embodiments, the thermal battery 1 employs a method such as... Figure 4 The heat exchanger 4 shown will be described in detail below. However, in other embodiments (such as...) Figure 13 As shown in the figure, another HEX 6 structure can be used, which in this example is a shell-and-tube heat exchanger with a serpentine tube bundle.

[0030] HEX 4 comprises multiple plates 5, each plate forming at least one fluid channel 7 extending through the plate. For example... Figure 5 , 6 As shown in Figure 7, the fluid flow channel 7 extends in a serpentine manner on both sides of each plate 5, connecting the inlet 8 and the outlet 9. Figure 8 An example of inlet 8 (which has the same structure as outlet 9) is shown. Fluid channels 7 on each plate 5 are used to transport the heat transfer fluid, typically water in the preferred embodiment, but other forms, such as ethylene glycol, may be used in other embodiments. During operation, the heat transfer fluid flows into inlet 8 located at the first edge 11 of plate 5, flowing along a straight segment 10 of fluid channel 7 that extends for most of the length from edge 11 to the opposite edge 12. The fluid channel 7 then enters a curved segment 13, causing the heat transfer fluid to turn 180°, and then enters another straight segment 14 that extends towards the first edge 11. The fluid channel 7 extends in this way through multiple straight and curved segments, ultimately serpentinely traversing most of the surface of plate 5, after which the heat transfer fluid flows out through outlet 9.

[0031] Each serpentine fluid flow channel 7 preferably comprises 14 to 18 straight segments 14. The illustrated preferred embodiment has a total of 16 straight segments 14, each 686 mm long, which are interconnected by a total of 15 curved segments 13. These curved segments have an inner radius of 8 mm and an outer radius of 26 mm. Each curved segment 13 is arranged adjacent to the edge 11 or 12 of the plate 5.

[0032] In some embodiments, the cross-sectional shape of the fluid channels is polygonal. In the illustrated embodiment, each fluid channel 7 has a quadrilateral rhombus cross-sectional shape 31. In some embodiments, the quadrilateral rhombus cross-sectional shape has a pair of equal and opposite interior angles, ranging from 46° to 89°, with the angle being 60° in the illustrated embodiment. In some embodiments, the shorter diagonal of the quadrilateral rhombus cross-sectional shape 31 is between 15 mm and 20 mm, with the length being 18 mm in the illustrated embodiment. In some embodiments, the longer diagonal of the quadrilateral rhombus cross-sectional shape 31 is between 22 mm and 31 mm, with the length being 27.2 mm in the illustrated embodiment. The two outer vertices of the rhombus cross-sectional shape 31 are rounded with a radius of approximately 2 mm. These dimensions are in... Figure 11 It gets the best display in the middle.

[0033] In another embodiment, the diameter of the circular cross-sectional shape of each fluid channel 7 is between 12 mm and 20 mm. In yet another embodiment, each fluid channel 7 has an elliptical cross-sectional shape.

[0034] The center-to-center distance between two adjacent straight segments 14 is preferably 30mm to 38mm, such as Figure 11 As shown, in this embodiment, the spacing is 34 mm. The length of the serpentine fluid channel 7 defined on each plate 5 is preferably 10.4 m to 13.1 m, and in this embodiment, the length is 11.8 m.

[0035] In one embodiment, each plate 5 is initially made from a pair of stainless steel sheets. In one manufacturing method, each sheet is stamped to form the left or right half of the plate, containing half of the fluid channel. The two sheets are then joined along the centerline of the plate, aligning the two halves of the fluid channel. The connection can be achieved using welding, adhesives, or other processes. In another manufacturing method, each plate is manufactured in one piece using a blow molding process, eliminating the need to assemble individual components. The final manufacturing step for plate 5 is to install inlets 8 and outlets 9 at both ends of the fluid channel 7.

[0036] like Figure 16 As shown, multiple plates 5 are arranged in a regular array inside the storage tank 2. Each plate 5 is parallel to the others and extends across the width of the storage tank 2, located between the rear wall 17 and the front wall 18 of the storage tank. Figure 5 and Figure 6 As shown, each plate 5 has a planar protrusion 19 on its third edge 15 and a planar protrusion 20 on its fourth edge 16. The planar protrusion 19 has a width of 42 mm, while the planar protrusion 20 has a width of 25 mm. Therefore, on each plate 5, the entire fluid flow channel 7 is offset relative to the outer periphery of the plate 5 towards the fourth edge 16. Figure 14 and 16As shown, the trough assembly 21 has multiple troughs 22 disposed on the inner side of the rear wall 17 of the tank. Another identical trough assembly 21 is disposed on the inner side of the front wall 18 of the tank. The troughs 22 of the two trough assemblies 21 are aligned with each other in the width direction of the tank 2, and the open ends of the troughs 22 both face the center of the tank 2. This design allows the protrusions 19 and 20 of each plate 5 to be placed in the troughs 22, thereby mounting the plate 5 in the tank 2 and presenting one of two possible offset options for the fluid flow channel 7. In the first offset option, the protrusion 19 with a width of 42 mm is installed in the trough 22 of the trough assembly 21 on the rear wall 17 of the tank, while the protrusion 20 with a width of 25 mm is installed in the trough 22 of the trough assembly 21 on the front wall 18 of the tank. This causes the fluid flow channel 7 to be offset towards the front wall 18 of the tank. In the second offset scheme, the wider protrusion 19 is installed in the groove 22 of the groove assembly 21 on the front wall 18 of the tank, and the narrower protrusion 20 is installed in the groove 22 of the groove assembly 21 on the rear wall 17 of the tank. This causes the fluid flow channel 7 to be offset towards the rear wall 17 of the tank. Each plate 5 is arranged in an alternating offset scheme within the tank 2, with adjacent plates forming a misalignment. Therefore, the fluid flow channel 7 of each plate 5 is offset relative to the fluid flow channel 7 of the adjacent plate 5. This results in the following... Figure 10 The overall cross-sectional flow channel layout is shown, with the cross-section taken from a horizontal plane passing through the midpoint of HEX 4.

[0037] More specifically, such as Figure 10 As shown, taking the leftmost plate 26 as an example, its fluid flow channel in the cross-sectional view is defined by sixteen diamond-shaped channels 31 on the plate 26. The fluid flow channel of the adjacent plate 27 is defined by 16 diamond-shaped channels 31 on its surface. It can be seen that the 16 diamond-shaped channels 31 in the flow channel of the leftmost plate 26 are staggered with the 16 diamond-shaped channels 31 in the flow channel of the adjacent plate 27. This alternating staggered pattern runs through all 40 plates 5 of HEX 4.

[0038] The centerline of each plate 5 is 29 mm away from the centerline of the adjacent plate 5, thus forming a volume 23 between the adjacent plates 5. The phase change material (PCM) is contained within this volume 23. Some of the PCM is also distributed in the volume 24 formed between the left end plate 26 and the left side wall 29 of the tank 4, and in the volume 24 formed between the right end plate 28 and the right side wall 30. Therefore, continuous heat exchange occurs between the PCM within volume 23 and the hot water flowing through the diamond-shaped channel 31. Specifically, during operation, heat is transferred from the hot water to the PCM via the 1 mm thick thermally conductive wall 25 constituting the fluid flow channel 7, and vice versa.

[0039] The inventors have recognized that the turbulence experienced by the heat transfer fluid as it flows through channel 7 affects the heat transfer efficiency of HEX 4. Insufficient turbulence reduces the heat transfer performance of HEX. Excessive turbulence may obstruct the flow of the heat transfer fluid in inlet 8, outlet 9, or channel 7. The specific design (e.g., shape and size) of the fluid channel 7 must ensure that the Reynolds number of the turbulence is maintained between 4000 and 7500, more preferably between 4500 and 7000, when the heat transfer fluid flows through the channel at the target operating flow rate. The target operating flow rate used for turbulence modeling is the median flow rate expected to be used in a typical heat exchange cycle. Under typical operating conditions, the median flow rate is approximately 1000 to 5000 kg / h. As shown in the preferred embodiment, the median flow rate is approximately 2400 kg of water per hour flowing through HEX 4.

[0040] like Figure 4 and Figure 16 As shown, HEX 4 includes an inlet manifold 32 that delivers hot water to the inlet 8 of the first plate 5. The hot water then flows through the flow channel 7 of the first plate, exits from the outlet 8 of the first plate 5, and enters the inlet of the adjacent plate 5 through the connecting pipe 33. This process continues until the hot water has flowed through all five plates 5. At this point, the hot water flows out from the outlet 9 of the fifth plate 5 and enters the exhaust manifold 34. This group of five plates 5 constitutes a channel, and the illustrated embodiment includes a total of eight channels.

[0041] In a typical embodiment, the thermal battery 1 is cooled overnight or charged using low-cost electricity until the phase change material (PCM) freezes. This freezing state can be achieved naturally due to the low nighttime temperatures or with the assistance of refrigeration equipment—for example, an air conditioning system that preferentially operates during off-peak electricity rates. The thermal insulation properties of the thermal battery 1 allow it to maintain the PCM frozen state even when temperatures rise the following day. When the ambient temperature rises, releasing the stored heat from the thermal battery 1 helps assist external cooling systems (e.g., air conditioning systems operating in hot weather). At this time, heat transfer water from the external system is pumped into the inlet manifold 32 and flows through the channels of the heat exchanger HEX 4 for cooling. The cooled water is then returned to the external system via the exhaust manifold 34. This configuration can effectively reduce the energy consumption of the external system during typical daytime peak electricity consumption periods, thereby achieving significant energy cost savings.

[0042] In another embodiment, the thermal battery is charged by cooling during periods of on-site power surplus or when low-cost renewable energy is available. Once charged, the thermal battery 1 can be discharged during peak cooling demand / high electricity price periods.

[0043] The PCM used inside HEX 4 typically has a low thermal conductivity (usually below 1 W / (m·K)), which hinders the rate of heat transfer to and from the PCM's interior and exterior. Increasing the heat transfer area between the PCM and HEX 4 can effectively reduce the thermal resistance of the PCM region, thereby improving heat transfer efficiency. However, increasing the heat transfer area usually leads to a higher cost for the HEX 4 system. Therefore, the design of HEX 4 needs to strike a balance between the thermal performance and cost of the thermal cell 1. This design aims to keep the thermal resistance of the PCM at a level close to that of the heat transfer fluid.

[0044] Figure 17 and Figure 18 The simulation results of thermal cell discharge using an ISO+5 PCM and the HEX 4 structure shown are presented. In this simulation, the initial PCM temperature was -3°C, the inlet water temperature was 15°C, and the water flow rate was 2400 kg / hr. The simulation revealed the following performance indicators.

[0045] ISO+5 simulation results.

[0046] Figure 19 and Figure 20 The simulation results of thermal cell discharge using an ISO+12 PCM and the illustrated HEX 4 structure are presented. In this simulation, the initial PCM temperature was 3°C, the inlet water temperature was 22°C, and the water flow rate was 2400 kg / hr. This simulation reveals the following performance indicators.

[0047] ISO+12 simulation results.

[0048] Figure 21 and Figure 22 The results of the exothermic simulation using an ISO+25 PCM and the illustrated HEX 4 thermal cell are presented. In this simulation, the initial temperature of the PCM was 17°C, the inlet water temperature was 35°C, and the water flow rate was 2400 kg / hr. This simulation reveals the following performance indicators.

[0049] ISO+25 simulation results.

[0050] While several preferred embodiments have been described, those skilled in the art will understand that particular operational requirements will necessitate numerous variations and / or modifications to the invention without departing from the broad spirit or scope of the invention as described above. Therefore, these embodiments should be considered illustrative rather than restrictive in all respects.

Claims

1. A phase change material (PCM) having a phase change temperature between about 3°C ​​and about 27°C, said PCM comprising: 35% to 60% (by weight) of inorganic salts; 1% to 9% (by weight) of nucleating agent; 1% to 4% (by weight) thickener; and 30% to 66% (by weight) water.

2. The PCM according to claim 1, wherein the phase transition temperature is about 3°C ​​to 6°C, and wherein the PCM comprises: 51% to 60% (by weight) of inorganic salts; 3% to 9% (by weight) of nucleating agent; 1% to 4% (by weight) thickener; and 30% to 40% (by weight) water.

3. The PCM according to claim 2, wherein the inorganic salt comprises: 38% to 43% (by weight) dipotassium hydrogen phosphate; and 13% to 17% (by weight) of potassium fluoride.

4. The PCM according to claim 2 or 3, wherein the nucleating agent comprises: 1% to 3% (by weight) dicalcium phosphate; 1% to 3% (by weight) aluminum oxide; as well as 1% to 3% (by weight) sodium chloride.

5. The PCM according to any one of claims 2 to 4, wherein the thickener is a superabsorbent polymer.

6. The PCM according to claim 5, wherein the superabsorbent polymer is sodium polyacrylate and / or carbomer.

7. The PCM of claim 1, wherein the phase transition temperature is between about 4°C and about 5°C, and wherein the PCM comprises: Approximately 40.3% (by weight) dipotassium hydrogen phosphate; Approximately 15.0% (by weight) potassium fluoride; Approximately 2.3% (by weight) dicalcium phosphate; Approximately 2.3% (by weight) aluminum oxide; Approximately 2.3% (by weight) sodium chloride; Approximately 2.7% (by weight) sodium polyacrylate and / or carbomer; and Approximately 35.2% (by weight) water.

8. The PCM according to claim 7, wherein the PCM has one of the following characteristics: The latent heat value is at least approximately 190 kJ / kg; The solid-state thermal conductivity is at least approximately 0.9 W / m·K; The liquid phase thermal conductivity is at least approximately 0.5 W / m·K; The solid phase heat capacity is at least approximately 1.4 kJ / kg·K; The liquid phase heat capacity is not less than approximately 2.0 kJ / kg·K; a solid phase density of not less than about 1700 kg / m 3 ; and / or a liquid phase density of at least about 1600 kg / m 3 .

9. The PCM of claim 1, wherein the phase transition temperature is between about 9°C and about 13°C, and wherein the PCM comprises: 48% to 58% (by weight) of inorganic salts; 1% to 3% (by weight) of nucleating agent; 1% to 3% (by weight) thickener; and 40% to 45% (by weight) water.

10. The PCM according to claim 9, wherein the inorganic salt comprises: 30% to 36% (by weight) sodium sulfate; as well as 18% to 22% (by weight) of ammonium chloride.

11. The PCM according to claim 9 or 10, wherein the nucleating agent comprises: 1% to 3% (by weight) sodium tetraborate.

12. The PCM according to any one of claims 9 to 11, wherein the thickener is a superabsorbent polymer.

13. The PCM according to claim 12, wherein the superabsorbent polymer is sodium polyacrylate and / or carbomer.

14. The PCM of claim 1, wherein the phase transition temperature is between about 10°C and about 12°C, and wherein the PCM comprises: Sodium sulfate, approximately 33.6% (by weight); Approximately 19.8% (by weight) ammonium chloride; Sodium tetraborate, approximately 2.0% (by weight); Approximately 2.0% (by weight) sodium polyacrylate and / or carbomer; and Approximately 42.6% (by weight) water.

15. The PCM according to claim 14, wherein the PCM has at least one of the following characteristics: The latent heat value is at least approximately 160 kJ / kg; The solid-state thermal conductivity is at least approximately 1.0 W / m·K; The thermal conductivity of the liquid phase is at least approximately 0.5 W / m·K; The solid phase heat capacity is at least approximately 1.4 kJ / kg·K; The liquid phase heat capacity is at least approximately 2.0 kJ / kg·K; a solid phase density of at least about 1500 kg / m 3 ; and / or a liquid phase density of at least about 1400 kg / m 3 .

16. The PCM of claim 1, wherein the phase transition temperature is between about 23°C and about 27°C, and wherein the phase transition material comprises: 35% to 43% (by weight) of inorganic salts; 1% to 3% (by weight) of nucleating agent; 1% to 3% (by weight) thickener; and 57% to 66% (by weight) water.

17. The PCM according to claim 16, wherein the inorganic salt comprises: 20% to 24% (by weight) disodium phosphate; as well as Sodium carbonate, 15% to 19% (by weight).

18. The PCM according to claim 16 or 17, wherein the nucleating agent comprises: 1% to 3% (by weight) sodium tetraborate.

19. The PCM according to any one of claims 16 to 18, wherein the thickener is a superabsorbent polymer.

20. The PCM according to claim 19, wherein the superabsorbent polymer is sodium polyacrylate and / or carbomer.

21. The PCM of claim 1, wherein the phase transition temperature is between about 24°C and about 26°C, and wherein the PCM comprises: Approximately 21.8% (by weight) disodium phosphate; Approximately 16.7% (by weight) sodium carbonate; Sodium tetraborate, approximately 2.0% (by weight); Approximately 2.0% (by weight) sodium polyacrylate and / or carbomer; and Approximately 61.5% (by weight) water.

22. The PCM according to claim 21, wherein the PCM has at least one of the following characteristics: The latent heat value is at least approximately 190 kJ / kg; The solid-state thermal conductivity is at least approximately 1.0 W / m·K; The liquid phase thermal conductivity is at least approximately 0.5 W / m·K; The solid phase heat capacity is at least approximately 1.4 kJ / kg·K; The liquid phase heat capacity is not less than approximately 2.0 kJ / kg·K; a solid phase density of not less than about 1500 kg / m 3 ; and / or a liquid phase density of at least about 1400 kg / m 3 .

23. A heat exchanger (HEX) comprising: Multiple plates, each plate forming at least one fluid flow channel extending through the plate, the fluid flow channel being used for the flow of heat transfer fluid; The plurality of plates are arranged in a regular array and spaced apart from each other to define the volume for accommodating the PCM between adjacent plates; When arranged in a regular array, the first flow channel extending through the first plate is offset relative to the second flow channel extending through the second plate adjacent to the first plate.

24. The HEX of claim 23, wherein the fluid channel is configured such that, in use, when the heat transfer fluid flows through the fluid channel at a target usage flow rate, the Reynolds number of the turbulence generated by the heat transfer fluid is between 4000 and 7500.

25. The HEX of claim 24, wherein the Reynolds number is between 4500 and 7000.

26. The HEX according to any one of claims 23 to 25, wherein each of the fluid channels has a polygonal cross-sectional shape.

27. The HEX according to any one of claims 23 to 26, wherein each of the fluid channels has a quadrilateral rhomboid cross-sectional shape.

28. The HEX of claim 27, wherein the quadrilateral rhomboid cross-sectional shape has a pair of equal and opposite interior angles between 46° and 89°.

29. The HEX according to claim 27 or 28, wherein the quadrilateral rhomboid cross-sectional shape has a short diagonal length between 15 mm and 20 mm and a long diagonal length between 22 mm and 31 mm.

30. The HEX according to any one of claims 23 to 25, wherein each fluid channel has a circular or elliptical cross-sectional shape.

31. The HEX of claim 30, wherein the diameter of the circular cross-sectional shape is between 12 mm and 20 mm.

32. The HEX according to any one of claims 23 to 31, wherein the fluid channel extending through each plate is offset relative to the outer periphery of the plate, such that each plate can be positioned within the HEX in one of two possible offset options.

33. The HEX of claim 32, wherein each plate is arranged in the HEX with an alternating offset option relative to an adjacent plate, such that the fluid flow path of each plate is offset relative to the fluid flow path of the adjacent plate.

34. The HEX according to any one of claims 23 to 33, wherein each fluid channel extends between the inlet and the outlet.

35. The HEX of claim 34, comprising an intake manifold configured in use to supply heat transfer fluid to at least a portion of the intake port, and an exhaust manifold configured in use to receive heat transfer fluid from at least a portion of the exhaust port.

36. The HEX according to any one of claims 23 to 35, wherein each of the fluid channels comprises 14 to 18 straight segments that span a large portion of the length between opposite edges of the plate and are interconnected by a plurality of curved segments located adjacent to the opposite edges of the plate.

37. The HEX according to claim 36, wherein the center-to-center distance between two adjacent straight segments is 30 mm to 38 mm.

38. The HEX according to any one of claims 23 to 37, wherein the length of each fluid channel defined on each of the said plates is between 10.4 m and 13.1 m.

39. The HEX of claim 24, wherein the target uses a flow rate between 1000 kg / h and 5000 kg / h.

40. The HEX according to any one of claims 23 to 39, wherein the fluid flow channel is serpentine.

41. A thermal battery, comprising: Storage tanks; The HEX contained within the storage tank; as well as PCM contained within the storage tank and undergoing heat exchange with the HEX.

42. The thermal battery of claim 41, wherein the PCM is defined as in any one of claims 1 to 22.

43. The thermal battery according to claim 41 or 42, wherein the HEX is defined as any one of claims 23 to 40.

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