Heat pump system, and heating method

Abstract

The object is to provide an improved heat pump system. [Solution] The heat pump system has a core made of a shape memory alloy (SMA), a negative thermal expansion material (NTE), or a thermoelastic material, and the first core is arranged inside a housing to absorb heat and store energy, and is configured to produce a net cooling effect when an input first fluid is output, the housing is configured to receive the first fluid from an inlet at a first temperature to cause the first core to change state at an activation temperature, and has a device that applies stress to the first core arranged inside the housing to cause a phase change and release heat / energy, and is configured so that when a second fluid at a second temperature or the first fluid at the first temperature is input to the first core, energy / heat from the heated first core is transferred and heated, and the second core is cascaded to the first core.

Description

Technical Field

[0001] The present disclosure relates to heat pumps. In particular, the present disclosure relates to heat pumps for heating systems and / or cooling systems such as air conditioning systems.

Background Art

[0002] Heat pump (“HP”) technology has received commercial support in heating, ventilation, and air conditioning (“HVAC”) applications. They provide energy savings and emissions reduction and are typically provided for heating and cooling systems in buildings, automotive applications, etc. and can be typically provided for heating and cooling systems in applications such as buildings and automotive uses.

[0003] There are several types of heat pumps. Most existing technologies utilize refrigerants in an expansion / compression cycle, and many heat pumps are classified as heat sources, for example, air source heat pumps or ground source heat pumps. The same applies to the basic technologies used in heat pumps. Air source heat pumps have limited performance at low temperatures (at -18°C, the CoP tends to be close to 1 (by Carnot). Therefore, electric resistance heating is more effective, and at higher operating temperatures, the CoP can reach 4). Ground source heat pumps have a more stable inlet temperature, but the prior art is limited by the coefficient of performance (“CoP”).

[0004] Worldwide, there is a need to decarbonize heating and cooling in buildings. Heating generally burns carbon-based fuels, releasing carbon into the atmosphere. Cooling and air conditioning can be a major electrical load in warmer climates. Heat pumps can potentially provide heating and cooling from a single package. When heat pumps use renewable electricity, they can be zero-emission technologies. Conventional heat pump technologies generally use refrigerants with a high potential for global warming and can have high toxicity, which is not desirable. Fans and pumps can have intrusive noise.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventional HP technology has a CoP of 3 - 4. By increasing the CoP, power consumption can be reduced, thereby reducing carbon emissions when non-renewable power is used. Further, conventional HP technology may have a CoP that is affected by the ambient air temperature, which is not desirable. US Patent Application Publication No. 20160084544 (Radermacher et al.) discloses a heat pump system using SMA material tubes, which are filled with other tubes or rods of unknown materials and occupy volume, and are thus useful for removing dead thermal mass and increasing the efficiency of the system. However, this configuration has problems such as poor thermal efficiency, non-uniform expansion and / or contraction, and poor CoP values generated.

Means for Solving the Problems

[0006] An object of the present invention is to provide a heat pump system with a significantly improved coefficient of performance (CoP). 。

[0007] This The heat pump system according to the invention is a core made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body, the core having a first core and a second core, the first core being arranged inside the housing so as to absorb heat heat and accumulate energy, at the inlet of the housing such that the input first fluid from the outlet of the housing results in a net cooling effect when output, and the first fluid is at a first temperature to cause a state change of the first core at the activation temperature the at the to inlet by to apply stress to the first core arranged inside the housing to cause a phase change by heat and release energy configured such that the second core is cascade-connected to the first core, and the such that the first fluid at the first temperature is input into the first core hasthing accumulated in the first core before heat energy is transferred to the second fluid when the second fluid at the second temperature is input to the first core, and the state of the second core changes in response to the heated second fluid is configured is .

[0008] With this configuration, heat energy to can be accumulated or released immediately or at a desired frequency according to the required application.

[0009] The housing receives a first fluid at a first temperature via an inlet by to change the state of the first core is configured is . the By applying stress to the first core disposed inside the housing to cause a phase change heat to release energy is configured by being , increasing the temperature of the core. Then, a second fluid at a second temperature (in certain cases, continuously the first fluid at the first temperature) is input into the core, and heat energy is from the internal fluid to is transmitted by , the when the fluid exits the core, a net heating effect is bring achieved. A second core made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body is cascade-connected to the first core and is configured to change its state according to the temperature of the fluid exiting the first core. Then, a stress cycle is repeated in the second core, and when the second fluid exits the second core, a further net heating effect (i.e., an increase in temperature) occurs.

[0010] Cooling system to In order to achieve a lower temperature drop to the cascade-connected second core can exhibit an activation temperature lower than that of the first core. The focus of the cycle is on the stress relaxation component of heat absorption where the core absorbs energy from the fluid. The first core causes a of temperature drop of the fluid, and then 、 enters the second core having a lower activation temperature, providing half of the cycle's coolingperiod There will be a further temperature drop of the output fluid therebetween.

[0011] The core can have any suitable elastocaloric material such as nickel-titanium alloy or derivatives NiTiX or NiTiXY (X and Y are ternary alloying elements / quaternary alloying elements), NiMnGa, CuAlZn, etc.

[0012] According to the heat pump according to the present invention, a substantially higher temperature delta (delta T) can be shown than that of the heat pump system of the prior art. According to the present invention, it contributes to an increase in heat output and an increase in system efficiency / CoP in the SMA / solid-state heat pump.

[0013] Here, the SMA heat pump / cooling The cycle can be regarded as a hybrid of the reverse Brayton and reverse Stirling cycles. At a higher delta T, it is closer to the reverse Brayton cycle, and at a lower delta T, it is closer to the reverse Stirling. Therefore, since the reverse Stirling is a more efficient cycle, it is best to operate the heat pump as close to this cycle as possible. By adopting a cascade system and connecting two or more cores in series, the delta T required to form each phase is reduced. This means that the system is closer to the reverse Stirling in its behavior. The exergy efficiency is also higher because the energy available in the SMA for heating the fluid is greater than in the case of a larger delta T.

[0014] As one embodiment, the second core is arranged in series with the first core and brings about a temperature rise during the heating cycle.

[0015] As one embodiment, the second core is arranged in series with the first core and brings about a temperature drop during the cooling cycle.

[0016] As one embodiment, the second core has a higher activation temperature compared to the first core.

[0017] In one embodiment, the second fluid includes a tertiary circuit fluid.

[0018] In one embodiment, the applied stress is a compressive stress.

[0019] In one embodiment, the second core changes state so that the temperature of the second fluid rises as the first core changes state, causing the temperature of the second fluid to rise.

[0020] In one embodiment, a core made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body, the core having a third core, the third core being cascade-connected to the first core and the second core. The heat pump / cooling system can be operated by stacking any number of cores or by cascade-connecting any number of cores.

[0022] The heating method according to the present invention is a core made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body, the core having a first core and a second core, the first core being arranged inside the housing so as to absorb heat and accumulate energy, at the inlet of the housing input has The first fluid from the outlet of the housing output produces a net cooling effect A heating method using a heat pump system configured such that the second core is cascade-connected to the first core, the first fluid at a first temperature to cause a state change of the first core at the activation temperature the inlet to put by Applying stress to the first core arranged inside the housing causes a phase change by heat release energy cause to heat, and then a second fluid at a second temperature to input to the first core heat the second fluid by transfer and then transfer the heat of the heated second fluid to the second core heat the second core .

Advantages of the Invention

[0023] According to the heat pump of the present invention, a substantially higher temperature delta (delta T) can be shown compared to the heat pump system of the prior art. According to the present invention, it can contribute to an increase in heat output and an increase in system efficiency / CoP in an SMA / solid state heat pump.

Brief Description of the Drawings

[0024] is FIG. 1 is a diagram showing a heat pump system composed of a plurality of cores made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0025] For a clearer understanding of the present invention, an embodiment as an example in the present invention will be described in detail below with reference to the drawings. The present invention relates to a novel heat pump cycle that utilizes the latent heat from a phase change in a material made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body. Hereinafter, the implementation of SMA is described as a preferred embodiment of the present invention, and it is similarly applicable to the implementation of a negative thermal expansion material (NTE) or a thermoelastic heat quantity material.

[0026] In the present invention, in order to define a core, SMAs composed of a plurality of elements or a plurality of wires can be used in close proximity. The material of the SMA can exist in two crystalline states, martensite and austenite, and can reversibly transform from one phase to the other. The transformation from austenite to martensite in the SMA is accompanied by heat generation. The transformation from martensite to austenite in the SMA is accompanied by heat absorption. The temperature at which the phase transition occurs can be manipulated by applying stress to the material of the SMA.

[0027] A shape memory alloy (SMA) is an alloy that exhibits a shape memory effect of returning to its pre-deformed shape when heated even after being deformed once. This material is a lightweight solid-state alternative to conventional actuators such as hydraulic, pneumatic, and motor-based systems.

[0028] The present invention relates to a heat pump system and a method thereof that can use any of a plurality of shape memory alloys (SMAs), a plurality of negative thermal expansion materials (NTEs), or a material composed of a thermoelastic body. As one embodiment, in particular, an SMA system composed of an SMA material can be used. As an example, in order to define a core, a plurality of elements (or a plurality of groups of elements) or a plurality of wires are arranged in close proximity. In another example, the core can be defined by one or more of a rod, a block, a ribbon, a chip or a plate, a 3D printed element, etc., and in any case, it can function as a core by receiving axial or lateral compression, compression and natural load, torsional stress.

[0029] A heat pump has two phases, namely, a heat absorption phase and a heat release phase. A machine cycle is defined as a complete heat absorption phase (endothermic) and a complete heat release phase (exothermic).

[0030] The heat absorption phase sets the stress applied to the material to an appropriate lower value used in cyclic operation that allows heat transfer into the SMA material. As a result, the activation temperatures of Austenite start (As) and Austenite finish (Af) are set to values lower than the input temperature of the fluid flow. The presence of a heat gradient enables heat transfer into the SMA by heat conduction and heat convection. Once the material is fully or partially transformed to austenite (i.e., when the temperature of the SMA material is higher than Af), the heat absorption phase is completed.

[0031] After increasing the stress on the austenitic SMA material, the heat release phase begins. This raises the activation temperatures of Martensite start (Ms) and Martensite finish (Mf) for the reverse transformation back to martensite. Once the value of Ms rises above the temperature of the input fluid flow, the reverse transformation begins. It is only completed when Mf also becomes higher than the temperature of the fluid flow. Then, the latent heat is released by the SMA material into the fluid flow, raising its temperature. The rate at which heat release occurs is a function of various thermodynamic conditions of the fluid flow such as heat gradient, flow rate, and turbulence.

[0032] A single fluid temperature input can be used in the system, and a series of valves can be used at the output of the chamber to direct the warmer fluid from the heat release phase towards the object to be heated while returning the colder fluid flow from the heat absorption phase to the fluid source. Multiple fluid temperature inputs can also be used.

[0033] Figure 1 shows a heat pump system incorporating a configuration known as an SMA drive system, but operating in reverse, and is incorporated herein by reference to PCT Patent Application No. PCT / EP2019 / 052300, filed by Exergyn Limited and not published. As shown in Figure 1, a low-pressure accumulator 1 is applied to an SMA core 2a or bundle in a martensitic state. When fluid is input into a chamber containing an SMA core 2a at a temperature higher than As and Af, the SMA material can absorb heat. Figure 2 is a workflow diagram showing different states in the operation of SMT. As a result of the low pressure (i.e., low stress) applied to the wire, both the austenite start temperature (As) and the austenite finish temperature (Af) decrease proportionally, and the transformation from martensite to austenite can be easily achieved at a lower input fluid temperature. As shown in Figure 2, a plurality of SMA wires within the core are heated up to the Af point. Af is set as the point of maximum contraction of the wire and represents a partial or complete transformation from martensite to austenite.

[0034] FIG. 3 shows, as one embodiment, a first SMA core 10 and a second SMA core 11 connected in cascade in place of the core 2a of FIG. 1. As a preferred embodiment of the present invention, there can be provided a heat pump system having a first core 10 made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body, which is arranged in a housing and absorbs heat and accumulates energy in response to a first fluid input at a first temperature. The housing is configured to receive a first fluid at a first temperature via an inlet and change the state of a first core 10 made of SMA or NTE or a thermoelastic body. A device (not shown) is configured to apply a stress to the first core 10 made of MA or NTE or a thermoelastic body within the housing to change the state of the core 10 in response to a second fluid at a second temperature. By arranging a device such as a hydraulic circuit, a pneumatic circuit, an electromechanical device or a thread, which is configured to apply a stress to the core, stress application to the core can be achieved. A second core made of a shape memory alloy (SMA) or a negative thermal expansion material (NTE) or a thermoelastic body is connected in cascade to the first core 10, and the second core is configured to change its state in response to the second fluid temperature.

[0035] The cascade of two or more solid state / SMA cores 10 and solid state / SMA 11 within a heat pump / cooler / refrigeration system allows for an increase in the efficiency of the heat pump system by enabling an increase in the temperature rise during heating or the temperature drop during cooling / refrigeration (referred to as the "delta T" or dT of the overall system). The SMA hybrid is configured to have different activation temperatures, and a first core and a second core that cooperate in series are selected.

[0036] As an example, in a heat pump, during the endothermic cycle, when exposed to the inlet fluid at a set "low" temperature, a hybrid capable of phase change / transformation to austenite is selected as the core 10. The difference between the austenite finish temperature and the fluid inlet temperature should be minimized.

[0037] Once the SMA has fully transformed to austenite, the core 10 is exposed to a "low - medium" temperature fluid. As one embodiment, a tertiary circuit that continuously circulates within a heat pump can be used as the heat carrier. Then, a load or stress is applied to the SMA core 10, shifting the activation temperature of the SMA to a temperature higher than the activation temperature of the tertiary fluid temperature, releasing heat and generating a "medium - high" temperature tertiary fluid. In a preferred embodiment, the load or stress is a compressive stress, or a compressive + lateral stress or a compressive + torsional stress. The compressive load is preferred over a tensile load as it lengthens the fatigue life of the material, results in a more complete phase transformation, and brings about significant high efficiency. Devices such as a hydraulic circuit, a pneumatic circuit, an electromechanical device or a thread are arranged to apply stress to the core, thereby causing stress to be applied to the core.

[0038] For core 11, an SMA hybrid or material with a higher activation temperature is selected compared to core 10, and it operates on the same principle as core 10 except that it is converted to austenite using the tertiary circuit fluid instead of the inlet fluid. The activation temperature in the cooling system is at a lower temperature. The same conditions as described above apply from the perspective that the difference between the austenite finish temperature and the tertiary circuit fluid at the inlet should be minimized.

[0039] Figure 4 shows a tank circuit or a similar device 12 arranged in series between the first core and the second core. The tank circuit 12 provides an indirect connection as a buffer that is useful for the efficiency of the cycle. By not directly connecting the cores, it becomes possible to operate the cores at different timing intervals. There is also the advantage of homogenizing the temperature of the fluid before entering core 11. Without the buffer tank, the initial input fluid temperature entering core 11 can be at a higher temperature due to the initially larger temperature gradient between the fluid and the SMA / NTE core. When the temperature within core 10 becomes uniform, the temperature of the outlet fluid entering core 11 becomes lower. This can affect the behavior.

[0040] FIG. 5 is a diagram showing an ideal cycle for the operation of two cores (in this embodiment, SMA hybrid cores) interacting in a cascade formation in a T-s outline. The tertiary circuit is shown as Th1 / Tc1.

[0041] The heat transfer rate within the core is desirably such that it enables rapid transfer of energy from or to the SMA, and a minimum temperature difference between the fluid inlet temperature and the austenite finish temperature is ensured. This can be achieved in an appropriate time and maximized by optimizing the first core shape and the second core shape. As an example, each SMA core can be fabricated using a 3D printed core shape, or using a conventional shape (rod, tube, etc.) or an unconventional polygonal shape.

[0042] The number of cascades and the amount of cores are not limited, but the balance between the energy input required to operate the system in a cascade and the benefits achieved is required from both the perspectives of cost and performance.

[0043] The heat pump systems and methods described herein have many applications, including heating (space heating, hot water boiler systems or hot water systems), cooling (air conditioning water cooling devices, process cooling), reversible heating and cooling in (building or automotive applications), and refrigeration (household and commercial / retail) cryogenic cooling. The heat pump systems and methods are effectively applicable to any heating or cooling system.

[0044] In this specification, the phrases "comprising," "including," "configured to," "configured," and any variations thereof, as well as the phrases "containing," "includes," "contained," "containing," and any variations thereof, are mutually replaceable and should be given the broadest possible interpretation.

[0045] The present invention is not limited to the embodiments described above, and various changes can be made to the configuration and details.

Claims

1. A core made of a shape memory alloy (SMA), a negative thermal expansion material (NTE), or a thermoelastic body, the core having a first core and a second core, the first core being arranged inside a housing so as to absorb heat and accumulate thermal energy, and the first fluid input at the inlet of the housing having a net cooling effect when output from the outlet of the housing, and the first fluid being put into the inlet at a first temperature to apply stress to the first core arranged inside the housing to cause a phase change and release thermal energy in order to change the state of the first core at the activation temperature, the second core being cascade-connected to the first core, and the thermal energy of the first core accumulated by inputting the first fluid at the first temperature being transmitted to a second fluid when the second fluid at a second temperature is input to the first core, and the state of the second core changing in response to the heated second fluid, a heat pump system.

2. The heat pump system according to claim 1, wherein the second core is arranged in series with the first core and configured to cause a temperature rise during a heating cycle.

3. The heat pump system according to claim 1, wherein the second core is arranged in series with the first core and configured to cause a temperature drop during a cooling cycle.

4. The heat pump system according to claim 1, wherein the activation temperature of the second core is higher compared to the first core so as to cause a greater temperature rise in the fluid output compared to when only one core is used.

5. The heat pump system according to claim 1, wherein the activation temperature of the second core is lower compared to the first core so as to cause a greater temperature drop in the fluid output compared to when only one core is used.

6. The heat pump system according to any one of claims 1 to 5, wherein the core has a third core, and the third core is cascade-connected to the first core and the second core.

7. A heating method using a heat pump system configured with a core made of a shape memory alloy (SMA), a negative thermal expansion material (NTE), or a thermoelastic body, the core having a first core and a second core, the first core being arranged inside a housing so as to absorb heat and accumulate energy, and being configured to provide a net cooling effect when a first fluid input at an inlet of the housing is output from an outlet of the housing, and the second core being cascade-connected to the first core, the method including causing a phase change to release thermal energy by applying stress to the first core arranged inside the housing by introducing the first fluid at a first temperature into the inlet to change the state of the first core at an activation temperature, then heating the second fluid by introducing a second fluid at a second temperature into the first core, and then transferring the heat of the heated second fluid to the second core to heat the second core.

Images