Thermal energy generation and storage device
The thermal energy generation and storage device with multiple PCM modules and independent heat transfer circuits addresses inefficiencies by optimizing heat exchange and storage, achieving flexible and efficient thermal energy utilization.
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- CLIVET
- Filing Date
- 2025-12-11
- Publication Date
- 2026-06-17
Smart Images
Figure IMGAF001_ABST
Abstract
Description
[0001] The present invention relates to a thermal energy generation and storage device of the type specified in the preamble of the first claim.
[0002] In particular, the present invention relates to a thermal energy generation and storage device in which the generation is carried out by a heat pump.
[0003] Several thermal energy generation and storage devices are currently known.
[0004] The generic term 'thermal energy' refers to both sensible heat and latent heat, which is typical, for example, of changes in state of specific materials.
[0005] Thermal energy generation systems can consist, for example, of a heat pump or other known systems.
[0006] Thermal energy storage systems can instead consist of tanks of fluids that can be heated and that can retain said heat to exchange it at the right time, for example for the generation of hot water for domestic, industrial or other uses.
[0007] For example, a heat storage system can consist of a water tank. This storage system has the disadvantage that, by storing only sensible heat in the storage devices of the prior art where it is heated below 100°C to store energy, the water quickly loses said heat by dissipating it into the environment.
[0008] To overcome said drawback, so-called PCMs (phase change materials) have been developed.
[0009] PCMs are materials that have a phase change at substantially selectable temperatures and, furthermore, during this phase change, they store energy with great efficiency both per unit of volume or mass and by effective retention of thermal energy. It is also known in the prior art to use the solid-liquid phase transition (and vice versa) to respectively store and release thermal energy.
[0010] However, even the PCMs used in prior art storage systems present some important drawbacks. In fact, thermal storage systems that use a single PCM to store / release thermal energy are well known. In this case, when the storage system works in combination with a generation system, it will be able to store energy efficiently at a specific temperature (i.e. the one that allows the PCM phase transition) and release thermal energy at the same temperature. These systems are not particularly flexible (they work by exploiting the advantages of PCMs only in the vicinity of its phase transition temperature).
[0011] Regarding the efficiency of these systems, often to provide thermal energy to a utility it is necessary to further heat or cool the fluid which interacts with the storage, which will provide heat at only one temperature, or an exchanger which supplies energy to the storage will provide unusable energy and with inefficient heat exchange to the PCM unless the exchange occurs close to the phase transition temperature of said PCM.
[0012] To reduce the aforementioned drawbacks, solutions using multiple PCMs with different phase transition temperatures are available in the literature.
[0013] Document US-B-11125510 essentially describes a heat exchanger with integrated thermal storage, provided with a new side using phase change material between and in thermal contact with the primary and secondary circuits, e.g. of a plate heat exchanger. The side helps to reduce, for example, leak flows in district heating applications or reduce energy losses during periods of low flow through the heat exchanger, reducing system response times and internal energy losses, while external energy storage units are reduced in number or potentially made obsolete. However, US-B-11125510 does not solve the problems described either, as it describes storage systems mainly used to stabilize the heat exchangers of the plants and upstream of the process of transmission of thermal energy to the various utilities.
[0014] In this situation, the technical task underlying the present invention is to devise a thermal energy generation and storage device capable of substantially overcoming at least part of the aforementioned drawbacks.
[0015] Within the scope of this technical task, an important aim of the invention is to obtain a thermal energy generation and storage device that allows, first of all, to increase the overall efficiency of the system, allowing the thermal energy of the generator to be effectively stored.
[0016] Another important aim of the invention is to create a thermal energy generation and storage device that allows high-quality thermal energy not to be wasted by stabilizing the thermal fluctuations of the fluid on the utility side.
[0017] An important task is to provide a storage system that allows flexible use of the existing heat sources, both in the storing and releasing phases with limited inefficiencies and heat waste losses.
[0018] Moreover, a further aim of the invention is to create a thermal energy generation and storage device in which the thermal energy storage can be exploited quickly and efficiently by the utilities connected to the system.
[0019] The specified technical task and purposes are achieved by a thermal energy generation and storage device as claimed in the appended claim 1.
[0020] Preferred technical solutions are highlighted in the dependent claims.
[0021] The features and advantages of the invention are clarified below by a detailed description of preferred embodiments of the invention, with reference to the attached drawings, wherein: Fig. 1 shows a schematic view of an example of a thermal energy generation and storage device according to the invention in a first embodiment in which the module comprises three different partitions; Fig. 2 shows a schematic view of a thermal energy generation and storage device that exchanges thermal energy directly with the PCM via a dedicated branch of the refrigerant circuit. Fig. 2 shows a schematic view of a third example of a thermal energy generation and storage device according to the invention.
[0022] In this document, the measurements, values, shapes, and geometric references (such as perpendicularity and parallelism), when associated with words like "about" or other similar terms such as "approximately" or "substantially", should be understood as allowing for measurement errors or inaccuracies due to production and / or manufacturing errors and, especially, minor deviations from the value, size, shape, or geometric reference with which they are associated. For example, such terms, when associated with a value, preferably indicate a deviation not exceeding 10% of the value itself.
[0023] Moreover, terms such as "first", "second", "upper", "lower", "main", and "secondary" when used do not necessarily identify an order, priority of relation, or relative position but may simply be used to more clearly distinguish different components from one another.
[0024] Unless otherwise specified, as inferred from the following discussions, terms such as "processing", "computing", "determining", "computation", or similar should be understood as referring to the action and / or processes of a computer or similar electronic computation device that manipulates and / or transforms data represented as physical quantities, such as electronic magnitudes of records of a computing system and / or memories, into other data similarly represented as physical quantities within computer systems, records, or other information storage, transmission, or display devices.
[0025] Unless otherwise indicated, the measurements and data reported in this text are to be considered as performed in International Standard Atmosphere ICAO ISO 2533:1975.
[0026] With reference to the Figures, the thermal energy generation and storage device according to the invention is generally denoted by reference number 1.
[0027] The thermal energy generation and storage device comprises at least one thermal energy generation system 2.
[0028] The generation system 2 is preferably a system that takes heat from the environment and circulates it within a closed path in which a working fluid can transfer the thermal energy.
[0029] Therefore, the generation system 2 is preferably a heat pump.
[0030] In even more detail, preferably, the generation system 2 operates with a trans-critical vapor compression cycle created by the carrier fluid. The working fluid is preferably carbon dioxide.
[0031] Therefore, the generation system 2 preferably comprises a plurality of components which are common to all systems acting as heat pumps. The generation and storage device according to the present invention is a system primarily associated with the production of heat for an end user, therefore the components of the generation system 2 will be described in this embodiment. It is easily understood by those skilled in the art that the same system and its advantages can be applied to the generation of cold, e.g. with a reversible heat pump and appropriate modifications to the thermal thresholds of the storage system 3.
[0032] In fact, the generation system 2 preferably comprises an evaporator 21. The evaporator 21 is essentially a heat exchanger, known per se, capable of allowing heat exchange between the external environment or source and the carrier fluid. Moreover, the generation system 2 preferably also comprises a compressor 22. The compressor 22 also known per se, is configured to compress the carrier fluid so as to further raise the temperature of the carrier fluid.
[0033] The generation system 2 according to the present invention implements a trans-critical vapor compression circuit. Said heat pump thus implements a trans-critical cycle, using a refrigerant with suitable characteristics such as carbon dioxide. Therefore, the generation system 2 comprises a gas cooler 20. The cooler 20, also known as gas cooler, is essentially a heat exchanger configured to allow the generation system 2 to transfer the heat received from the carrier fluid to the outside of the generation system 2. Therefore, at the cooler 20, the carrier fluid preferably cools down, reducing its temperature as a result of the heat transfer to the outside. Unlike sub-critical cycles in which the heat-releasing exchanger (condenser) has an ideally constant refrigerant temperature profile, the temperature profile of a cooler is ideally similar to a decreasing monotone polygonal chain.
[0034] In conclusion, preferably, the generation system 2 comprises an expansion valve 23. In trans-critical systems the expansion valve is also called a high pressure valve. The expansion valve 23 is configured to expand the carrier fluid in such a way as to decrease / control the pressure of the refrigerant fluid downstream thereof, before the latter reaches the evaporator 21 again. As already mentioned, all these components are well known to a person skilled in the art.
[0035] However, the system 1 also comprises a thermal energy storage system 3.
[0036] The storage system 3 is configured to store at least part of the thermal energy circulating in the generation system 2 so as to compensate for any undesired energy dispersions.
[0037] In this regard, preferably, the storage system 3 comprises a plurality of storage modules 30. Said modules 30 are preferably physically and thermally separate from one another.
[0038] The module 30 is the portion of the storage system 3 inside which heat storage takes place. They preferably include tanks suitable for containing thermal storage fluids, such as PCM and / or water, as better described below.
[0039] In more detail, preferably, there are a plurality of modules 30 and therefore preferably at least a first module 30a and a second module 30b.
[0040] Preferably, said first module 30a includes a first phase change material. The first phase change material, otherwise known as PCM, thus defines a first phase transition temperature.
[0041] Moreover, the second module 30b preferably comprises a second phase change material. The second phase change material thus defines a second phase transition temperature.
[0042] Preferably, each module 30 of said storage system 3 includes a phase change material defining a different phase transition temperature.
[0043] Preferably, the first phase transition temperature is preferably comprised between 30°C and 50°C, more preferably comprised between 35°C and 45°C, even more preferably about 40°C.
[0044] Preferably, the second phase transition temperature is higher than the first phase transition temperature.
[0045] For example, preferably, the second phase transition temperature is preferably comprised between 70°C and 90°C, more preferably comprised between 75°C and 85°C, even more preferably about 80°C.
[0046] The module 30 also, preferably, comprises a third module 30c.
[0047] If present, the third module 30c also comprises a third phase change material or, alternatively, a water tank, such as in the embodiment shown in Fig.2. Preferably, said third module is placed in series between said first module 30a and said second module 30b.
[0048] If there is a third phase change material, a third phase transition temperature is preferably defined. Preferably, the third phase transition temperature is higher than the first phase transition temperature. Moreover, preferably, the third phase transition temperature is lower than the second phase transition temperature. Said third phase transition temperature is preferably comprised between 50°C and 70°C, more preferably comprised between 55°C and 65°C, even more preferably about 60°C.
[0049] Further modules 30 can also be provided.
[0050] The device 1 also comprises a first heat transfer circuit 31 of 31, part of the storage system 3 but also of the generation system 2.
[0051] In particular, preferably, the first circuit 31 allows heat exchange between the storage system 3 and the generation system 2.
[0052] In one embodiment (Figs.1 and 2) said circuit 31 comprises at least one pipe containing a first carrier fluid, a first exchanger and an exchanger system 311. Said heat transfer circuit 31 is operatively connected to said modules 30 through said system 311.
[0053] The first heat exchanger can coincide with the cooler 20 (Figs. 1 and 2), allowing heat exchange between said first exchange circuit 1, and the working fluid of the generation system 2, in particular of the heat pump. The first exchange circuit 31 thus allows the transfer of heat energy between the generation system 2 and the modules 30.
[0054] Preferably, the first circuit 31 is operatively connected to each module 30 through a respective heat exchanger that is part of said exchanger system so that the heat exchange with each module 30 can be independent of the exchange with the others. Therefore, advantageously, the first heat exchanger is operatively connected to each module 30, independently from each other module 30 through said exchanger system 311.
[0055] Alternatively (Fig.3), however, the first circuit 31 can transfer heat energy from the generation system 2 to the module 30 through a first transfer fluid which coincides with the working fluid of the generation system. In fact, in this embodiment, the heat transfer circuit 31 coincides with a section of the generator's refrigeration circuit or, better yet, heat pump 2. It will be clear that in this solution the cooler 20 of the generation system 2 coincides with said exchanger system 311.
[0056] Preferably, the first circuit 31 is configured to circulate said first transfer fluid in series first at the module including material at higher phase transition temperature.
[0057] In the embodiment of the invention described herein the circuit 31 is thus configured so as to make the first transfer fluid circulate in series first at the second module 30b and then at the first module 30a. Preferably, if intermediate modules 30 are present, the transfer fluid also passes in succession through these, so that the transfer fluid, when at a higher temperature, exchanges heat with the second module 30b and when at a lower temperature it exchanges heat with the first module 30a. Preferably, if water is present, it is affected by the heat exchange between the first and second module.
[0058] If the first exchanger of the heat transfer circuit 31 coincides with the cooler 20, the latter is preferably configured in such a way that the working fluid (i.e. refrigerant) circulates counter-current with respect to the first transfer fluid.
[0059] The storage system 3, advantageously, also comprises a second heat transfer circuit 32.
[0060] The second circuit 32 is similar to the first circuit 31.
[0061] Therefore, in one embodiment shown in Fig. 1, the second circuit 32 in turn defines a closed path within which a second heat transfer fluid can be directed and which, when operatively connected to another element of the device 1, can exchange thermal energy with that element.
[0062] In this embodiment (Fig.1) said circuit 32 comprises at least one pipe containing a second carrier fluid, a second exchanger and an exchanger system 312.
[0063] In addition, the second heat exchanger is configured to be connected to a utility 4. In any case, preferably, the second heat exchanger 32 is capable of transferring thermal energy from the module 30 to the utility 4.
[0064] Said second heat transfer circuit 32 is operatively connected to said modules 30 through said system 312. Said system 312 is capable of taking thermal energy from the modules 30.
[0065] Like the first heat exchanger 31, preferably, also the second circuit 32 is operatively connected to each module 30 independently of each other module 30.
[0066] In an alternative embodiment shown in Figs. 2 and 3, said second circuit 32 substantially coincides with said utility 4, or with at least part of it, and in particular the second transfer fluid is substantially domestic water and / or water from a secondary circuit for room heating (Figs.2 and 3). In this specific embodiment of the invention said second exchanger is absent.
[0067] Furthermore, in general, the utility 4 can be provided by a utility fluid, such as water present in a building's water supply system and / or another device that can receive heat from the system device 1.
[0068] Alternatively, said second circuit 32 and specifically said second system 312 can be open, comprising a delivery and a suction, at the level of least one module 30 (Fig. 2). A person skilled in the art will understand that in this case the affected module does not contain PCM.
[0069] Preferably, said affected module is said third module 30c.
[0070] Therefore, said third module 30c includes the same circulating fluid present in said second heat exchange circuit 32, and wherein said circuit 32 is an open circuit at the level of the module 30c (Fig.2).
[0071] This implementation is more advantageous if the second heat transfer fluid coincides with domestic hot water (DHW).
[0072] As is clear, in some embodiments of the invention said first and second heat transfer circuits 31, 32 comprise a pump to move the respective transfer fluids.
[0073] When the heat transfer fluid and the utility fluid do not coincide, the modules 30 are also advantageously configured in such a way that the second transfer fluid also circulates counter-current with respect to the utility fluid.
[0074] Moreover, preferably, the first heat transfer circuit 31 and / or the second heat transfer circuit 32 comprise a bypass device 33 upstream of at least one module 30 and more preferably of each individual module 30. Even more preferably the invention provides for at least one of said first and second exchanger systems 311, 321 a bypass device 33 configured to selectively thermally connect each module 30 with said first and second heat transfer circuits 31, 32.
[0075] The bypass device 33 is substantially configured to selectively permit or divert the flow of a transfer fluid. In fact, in particular, the bypass device 33 is configured to allow the flow of the related transfer fluid and / or utility fluid and / or refrigerant fluid as discussed in this document, upstream of each individual module 30, to avoid a single module or to exchange heat with the same single module. Preferably, in this regard, the bypass device 33 comprises a valve 33a and a bypass fitting 33b.
[0076] The valve 33a is conveniently a three-way valve. Alternatively, the valve 33a is a hydraulic combination of several two-way valves. Therefore, the bypass valve 33a preferably connects two circuit parts to the bypass fitting 33b.
[0077] Even more in detail, preferably, the bypass fitting 33b is positioned upstream, through the valve 33a, and downstream of a partition 30a, 30b, 30c or of the utility 4.
[0078] In other words, the bypass fitting 33b hydraulically creates a fluid passage in parallel to a single module 30.
[0079] Advantageously, the bypass valve 33a is configured to select the direction according to the following preferred modes.
[0080] In a preferred embodiment the bypass device 33 further comprises a plurality of temperature sensors. Preferably, said sensors are placed upstream of each fitting 33b and allow the bypass system to be controlled as described below.
[0081] The bypass valve 33a may in particular direct the first transfer fluid into the first heat exchanger 31 exclusively towards the bypass fitting 33b, cutting off a module 30, and, consequently, allows the first transfer fluid to interact with the phase change material of a module 30 only if the temperature of a transfer fluid (first fluid or refrigerant) is suitable for allowing the material to store thermal energy.
[0082] Likewise, preferably, the bypass valve 33a is also configured to direct the second transfer fluid into the second circuit 32 exclusively towards the bypass fitting 33b when the second transfer fluid has a lower temperature than the phase transition temperature of the module 30.
[0083] Thus, the second transfer fluid interacts with the phase change material only when it can accommodate thermal energy from it.
[0084] The operation of the energy generation and storage device 1 described above in structural terms is largely similar to most known systems. However, differently, the system 1 efficiently stores the heat transferred from the working fluid through the cooler 20 to the utility 4.
[0085] This is possible thanks to the storage system 3, placed between module 30 and cooler 20, which, thanks to a module containing a PCM with a low (relative to the other modules) transition temperature, is able to thermally filter any unwanted fluctuations (e.g. of the utility fluid), preventing the dispersion of higher quality thermal energy which is instead stored by the modules containing PCM with a higher phase transition temperature.
[0086] Furthermore, it is advantageous to couple a plurality of modules containing PCMs with different phase transition temperatures to a trans-critical vapor compression system cooler. This coupling allows to exploit the characteristic temperature curve of a cooler by offering a plurality of heat sinks (i.e. modules) capable of exchanging thermal energy efficiently (since it is possible to properly couple various temperatures of receiving fluid / PCM to the specific temperature of the first transfer fluid or of the refrigerant fluid or of the refrigerant fluid in that section of the exchange circuit).
[0087] Therefore, the invention also comprises a new thermal energy storage process. The process is, advantageously, implemented by the system 1 as previously described.
[0088] In one example of operation, the device allows the first transfer fluid or refrigerant fluid in the first circuit 31 to be directed through the valve 33a exclusively towards the bypass fitting 33b of a first module if said first fluid does not have a temperature sufficient to charge the PCM of said first module.
[0089] Furthermore, the device 1 allows the second transfer fluid or the utility fluid to be directed through the valve 33a in the second heat exchanger 32 in at least one module depending on the temperature of the utility fluid required by a utility (demand for domestic hot water for a shower) and / or a system (heating).
[0090] The device 1 according to the invention thus achieves important advantages.
[0091] In fact, the device 1 first allows the overall efficiency of the system to be increased, allowing the thermal energy to be effectively stored, which would otherwise be dispersed by a system according to the prior art.
[0092] Moreover, the device 1 allows to stabilize the transmission of thermal energy at least on the utility side and to use only the modules needed to produce the energy required to heat a utility, which is extremely advantageous when using PCMs as the unaffected module will retain the thermal energy for future uses with limited losses. In conclusion, in the device 1 the thermal energy storage is exploited quickly and with high performance by the utilities connected to the system.
[0093] The invention is subject to variations within the scope of the inventive concept defined by the claims.
[0094] Within this scope, all details can be replaced by equivalent elements, and materials, shapes, and dimensions may be any.
Claims
1. Thermal energy generation and storage device (1) comprising: - a thermal energy generation system (2); - a thermal energy storage system (3) including a plurality of modules (30) physically and thermally separated; - a first heat transfer circuit (31) operatively connected to said modules (30), through a first exchanger system (311), and to said generation system (2) and capable of transferring thermal energy from said generation system (2) to said modules (30) through a first transfer fluid; and being characterized in that - said modules (30) comprise at least a first and second module (30a, 30b) each including a phase change material, each material defining a different phase transition temperature, - said first circuit (31) is configured to circulate said first transfer fluid in series first at the module including material at higher phase transition temperature; - said storage system (3) further comprises a second heat transfer circuit (32) operatively connected to at least said modules (30), wherein said second circuit (32) is connected in series to said modules (30) through a second heat exchanger system (321), first at the module including material at lower phase transition temperature.
2. Device (1) according to claim 1, wherein said generation system (2) is a heat pump.
3. Device (1) according to any preceding claim, wherein said heat pump implements a trans-critical vapor compression circuit.
4. Device (1) according to any preceding claim, wherein said modules (30) further comprise a third module (30c), placed in series between said first module (30a) and said second module (30b).
5. Device (1) according to the preceding claim, wherein said third module (30c) including a third phase change material defining a third phase transition temperature higher than said first phase transition temperature and lower than said second phase transition temperature.
6. Device (1) according to at least claims 1 and 3, wherein said third module (30c) includes the same circulating fluid present in said second heat exchange circuit (32), and wherein said circuit (32) is an open circuit at the level of the module (30c).
7. Device (1) according to at least claims 1, 2, 3, wherein said first heat transfer circuit (31) and said heat exchanger (20) of said generation system (2) are in counter-current configuration.
8. Device (1) according to any of the preceding claims, wherein said storage system (3) comprises, for at least one of said first and second exchanger systems (311, 321) a bypass device (33) configured to selectively thermally connect each module (30) with said first and second heat transfer circuits (31, 32).
9. Device (1) according to any of the preceding claims, wherein said first and second heat transfer circuits (31, 32) comprise a pump to move the respective transfer fluids.
10. Device (1) according to any of the preceding claims except claim 5, wherein said first module (30a) includes a first phase change material defining a phase transition temperature comprised between 70 and 90°C, wherein said second module (30b) includes a second phase change material defining a phase transition temperature comprised between 30 and 50°C, and wherein said third module (30c) includes a third phase change material defining a phase transition temperature comprised between 50 and 70°C.
11. Device (1) according to any of the preceding claims, wherein said bypass device (33) further comprises a plurality of temperature sensors.
12. Device (1) according to any of the preceding claims, comprising a heat exchanger (20) capable of transferring thermal energy from said generation system (2) to said first heat transfer circuit (31).