A combined refrigeration system based on elasto-caloric and pressure-caloric effects

Abstract

The present invention discloses a combined refrigeration system based on the elastic-caloric and pressure-caloric effect, wherein a high-pressure valve is arranged between the elastic-caloric and pressure-caloric combined refrigeration element and the cold-end heat exchanger, the high-pressure end of the hydraulic pump is connected to the elastic-caloric and pressure-caloric combined refrigeration element via a piston cylinder, a pressure relief valve is arranged between the high-pressure end and the low-pressure end of the hydraulic pump, the low-pressure end of the hydraulic pump is connected to the hydraulic oil tank, and a circulating water pump is arranged between the high-pressure valve and the cold-end heat exchanger; the elastic-caloric and pressure-caloric combined refrigeration element is a double-layer pipe composed of polymer materials and shape memory alloys. The present invention pressurizes and releases the elastic-caloric and pressure-caloric combined refrigeration element, so that the polymer material of the inner layer of the pipe produces a pressure-caloric effect under the action of pressure, and at the same time, the shape memory alloy of the outer layer of the pipe produces an elastic-caloric effect under the action of tension, and utilizes the circulation of the heat exchange fluid between the elastic-caloric and pressure-caloric combined refrigeration element and the cold-end heat exchanger to achieve a refrigeration effect.

Description

Technical Field

[0001] The invention belongs to the technical field of refrigerators and relates to a combined refrigeration system based on elastic-caloric and pressure-caloric effects. Background Art

[0002] Refrigeration technology is closely related to modern human life. Traditional vapor compression refrigeration technology has been widely used in refrigerators, air conditioners and other fields, but the fluorine-containing refrigerants it uses can damage the ozone layer or cause the greenhouse effect. With the increasing environmental crisis, the development of a new generation of green and environmentally friendly refrigeration technology has become an urgent task. Solid-state refrigeration technology, which is based on the heat absorption / release effect of solid materials driven by an external field, is expected to replace traditional vapor compression refrigeration technology and has received widespread attention.

[0003] Solid-state refrigeration technology includes multiple branches. Among them, refrigeration technology based on the elastocaloric effect and pressure-caloric effect of solids are two important technical routes. The elastocaloric effect refers to the endothermic and exothermic effects accompanied by the phase change of solid materials under the drive of uniaxial stress. The elastocaloric effect is more common in shape memory alloys. The pressure-caloric effect is the endothermic and exothermic effect accompanied by the change of molecular, atomic or electronic order of solid materials under the drive of isostatic pressure. The pressure-caloric effect is commonly found in various materials such as alloys, inorganic salts, polymers and small molecule organic matter.

[0004] Current caloric refrigerants mostly use motors and mechanical components to achieve the stretching and unloading of caloric refrigerants, as well as the contact and separation of caloric refrigerants with the hot and cold ends. Some design schemes in the prior art cancel the traditional motor drive structure and use the stress generated by the phase change of high-temperature shape memory alloys to drive low-temperature shape memory alloys to produce caloric refrigerants to achieve refrigeration. This design scheme places high demands on the stress direction and transmission efficiency of high-temperature shape memory alloys, and multiple heat exchange fluid circuits need to be switched in a certain sequence, and the control strategy is relatively complex.

[0005] Most of the current autoclave refrigeration devices use a rigidly designed high-pressure cavity to load the refrigerant, and set up two high-pressure and low-pressure heat exchange fluid circuits. The high-pressure cavity is connected after pressure is applied and after pressure is released, respectively, to bring out the heat and cold. Another prior art discloses a design scheme for an autoclave refrigerator, which uses a cylindrical pressure vessel to load the refrigerant, and sets the pressure variation range to 0.1 to 400 MPa based on the performance range of existing autoclave refrigerants. Its maximum pressure is much higher than the 3 to 4 MPa of traditional gas compression refrigerators. If a cylindrical pressure vessel with an inner diameter of 200 mm is made of high-strength alloy steel with a tensile strength of 1000 MPa, even without considering the safety margin, according to the cylindrical wall annular tension formula ( Where P is the pressure inside the container, D is the inner diameter of the cylinder, and δ is the thickness of the cylinder wall). It is estimated that a wall thickness of at least about 40mm is required to withstand a pressure of 400MPa. Thick-walled high-pressure containers and independently installed high-pressure heat exchange pipelines will bring problems in terms of volume and weight; in addition, thick-walled containers themselves do not have refrigeration capabilities, but their huge heat capacity becomes the load of the refrigeration system, which will bring problems with heat exchange rate and refrigeration efficiency. Summary of the invention

[0006] To solve the above problems, the present invention provides a combined refrigeration system based on elastic-caloric and pressure-caloric effects, including an elastic-caloric and pressure-caloric combined refrigeration element, a cold end heat exchanger, a high-pressure valve, a hydraulic pump, a piston cylinder and a circulating water pump, wherein:

[0007] A high-pressure valve is arranged between the elastic-heat and pressure-heat combined refrigeration element and the cold-end heat exchanger, the high-pressure end of the hydraulic pump is connected to the elastic-heat and pressure-heat combined refrigeration element via a piston cylinder, a pressure relief valve is arranged between the high-pressure end and the low-pressure end of the hydraulic pump, the low-pressure end of the hydraulic pump is connected to the hydraulic oil tank, and a circulating water pump is arranged between the high-pressure valve and the cold-end heat exchanger;

[0008] The elastic-caloric and pressure-caloric combined refrigeration element is a double-layer pipeline, including a polymer material inner layer and a shape memory alloy braided layer. The polymer material inner layer has a pressure-caloric effect; the shape memory alloy braided layer has an elastic-caloric effect.

[0009] Preferably, the liquid inlet and the liquid outlet of the elastic-heat and pressure-heat combined refrigeration element are respectively connected to the liquid outlet and the liquid inlet of the cold-end heat exchanger through two high-pressure valves.

[0010] Preferably, the two high-pressure valves are opened or closed synchronously under the control of electrical signals; in the closed state, both ends of the elastic-thermal and pressure-thermal combined refrigeration element are closed, and its internal space becomes a pressure vessel; in the open state, the elastic-thermal and pressure-thermal combined refrigeration element is connected to the cold-end heat exchanger, thereby forming a heat exchange circuit.

[0011] Preferably, the hydraulic pump is used to apply pressure to the elastic-heat and pressure-heat combined refrigeration element when the high-pressure valve is closed.

[0012] Preferably, the piston cylinder is connected to the elastic-thermal and pressure-thermal combined refrigeration element and the high-pressure end of the hydraulic pump, so as to transmit pressure and isolate the hydraulic oil and the heat exchange fluid.

[0013] Preferably, the circulating water pump is used to drive the heat exchange fluid to circulate in the heat exchange circuit when the high-pressure valve is open, and carry the cold energy generated by the pressure relief to the cold-end heat exchanger.

[0014] Preferably, an insulation box is arranged outside the elastic heating and pressure heating combined refrigeration element, and the insulation box is provided with a plurality of air doors, at least one of which is connected to a fan to blow air into the insulation box, and the remaining air doors are used for ventilation of the insulation box.

[0015] Preferably, the polymer material is polyethylene, polypropylene, polyurethane, polytetrafluoroethylene, polydimethylsiloxane, natural rubber, nitrile rubber, silicone rubber and ethylene-vinyl acetate copolymer.

[0016] Preferably, the shape memory alloy material is Ni-Ti alloy.

[0017] Preferably, the elastic heat and pressure heat combined refrigeration elements are arranged in a spiral, U-shaped or S-shaped arrangement;

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: the present invention adopts a shape memory alloy with superelasticity and large deformation ability as the pressure-bearing layer of the polymer flexible pipe, and transmits tension to the shape memory alloy of the outer layer through the polymer material of the inner layer of the pipe, so as to achieve the superposition effect of the inner layer's pressure-heat cooling and the outer layer's elastic-heat cooling. The present invention uses the flowing air outside the double-layer pipe to take away the heat generated during pressurization, and uses the heat exchange fluid in the double-layer pipe to take out the cold generated during pressure relief. The double-layer pipe simultaneously serves as an elastic-heat working medium, a pressure-heat working medium, a high-pressure container and a high-pressure hot-end heat exchanger, avoiding the complex mechanical drive components in the traditional elastic-heat refrigerator, and the adverse effects of the thick-walled high-pressure cavity and the hot-end heat exchanger independently set in the traditional pressure-heat refrigerator on the volume, weight and refrigeration efficiency of the refrigerator. Therefore, the present invention has the advantages of simple structure, small volume, light weight, high efficiency and easy implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of a combined refrigeration system based on elastic-caloric and pressure-caloric effects according to an embodiment of the present invention;

[0020] Figure 2 It is a schematic diagram of the specific structure of the elastic-caloric and pressure-caloric combined refrigeration element of the combined refrigeration system based on the elastic-caloric and pressure-caloric effects according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. Those skilled in the art can fully understand the present invention without the description of these details.

[0023] See also Figure 1 , 2 , which is a schematic diagram of the structure of a combined refrigeration system based on elastic-caloric and pressure-caloric effects according to an embodiment of the present invention, includes an elastic-caloric and pressure-caloric combined refrigeration element 1, a cold end heat exchanger 2, a high-pressure valve 3, a hydraulic pump 5, a piston cylinder 6 and a circulating water pump 4, wherein:

[0024] A high-pressure valve 3 is provided between the elastic-heat and pressure-heat combined refrigeration element 1 and the cold-end heat exchanger 2, a high-pressure end of a hydraulic pump 5 is connected to the elastic-heat and pressure-heat combined refrigeration element 1 via a piston cylinder 6, a pressure relief valve 7 is provided between the high-pressure end and the low-pressure end of the hydraulic pump 5, a low-pressure end of the hydraulic pump 5 is connected to a hydraulic oil tank 8, and a circulating water pump 4 is provided between the high-pressure valve 3 and the cold-end heat exchanger 2;

[0025] The elastic-caloric and pressure-caloric combined refrigeration element 1 comprises a polymer material inner layer 101 and a shape memory alloy braided layer 102, which are made into a double-layer pipe. The polymer material inner layer 101 has a pressure-caloric effect; the shape memory alloy braided layer 102 has an elastic-caloric effect.

[0026] The liquid inlet and the liquid outlet of the elastic-heat and pressure-heat combined refrigeration element 1 are connected to the liquid outlet and the liquid inlet of the cold-end heat exchanger 2 through two high-pressure valves 3 respectively.

[0027] The two high-pressure valves 3 are opened or closed synchronously under the control of electrical signals; in the closed state, both ends of the elastic-heat and pressure-heat combined refrigeration element 1 are closed, and its internal space becomes a pressure vessel; in the open state, the elastic-heat and pressure-heat combined refrigeration element 1 is connected to the cold-end heat exchanger 2, thereby forming a heat exchange circuit.

[0028] The hydraulic pump 5 is used to apply pressure to the elastic and pressure combined refrigeration element 1 when the high-pressure valve 3 is closed.

[0029] The piston cylinder 6 connects the elastic-heat and pressure-heat combined refrigeration element 1 and the high-pressure end of the hydraulic pump 5, and is used to transmit pressure and isolate the hydraulic oil and the heat exchange fluid.

[0030] The circulating water pump 4 is used to drive the heat exchange fluid to circulate in the heat exchange circuit when the high-pressure valve 3 is open, and carry the cold energy generated by the pressure relief to the cold-end heat exchanger 2.

[0031] A heat preservation box 9 is arranged outside the elastocaloric and piezocaloric combined refrigeration element 1. The heat preservation box 9 is provided with a number of air dampers 10, at least one of which is connected to a blower 11 to blow air into the heat preservation box 9, and the remaining air dampers 10 are used for the ventilation of the heat preservation box 9. The blower 11 and the air dampers 10 can be opened or closed according to different stages of the refrigeration cycle. In the open state, the normal temperature air flowing through the heat preservation box 9 takes out the heat generated during pressurization, and the elastocaloric and piezocaloric combined refrigeration element 1 serves as a hot end heat exchanger; in the closed state, the heat preservation box 9 can isolate the external normal temperature environment, and the cold quantity generated during pressure relief is taken out by the heat exchange fluid. The heat exchange fluid fills the internal spaces of the elastocaloric and piezocaloric combined refrigeration element 1 and the cold end heat exchanger 2, and the heat exchange fluid is preferably ethylene glycol antifreeze.

[0032] The polymer materials are polyethylene, polypropylene, polyurethane, polytetrafluoroethylene, polydimethylsiloxane, natural rubber, nitrile rubber, silicone rubber and ethylene-vinyl acetate copolymer. The polymer materials have the following characteristics: the temperature rises when pressurized under adiabatic conditions, and the temperature drops when depressurized under adiabatic conditions. The inner wall of the inner layer 101 of the polymer material has raised ridges for increasing the loading amount of the polymer material and the contact area between the polymer material and the heat exchange fluid.

[0033] The shape memory alloy material is Ni-Ti alloy. The alloy material has the following characteristics: the temperature rises when loaded and stretched under adiabatic conditions, and the temperature drops when unloaded and shrinks under adiabatic conditions. The shape memory alloy braided layer 102 is a casing, a multi-layer fine wire or a braided grid of strips; the shape memory alloy layer generates axial and radial binding forces on the polymer material layer, thereby providing pressure-bearing capacity; according to parameters such as the outer diameter of the polymer material layer, the driving pressure of the piezocaloric effect, and the driving stress of the elastocaloric effect, referring to the circumferential tension formula of the cylinder wall, the thickness of the alloy layer is designed. The elastocaloric and piezocaloric combined refrigeration element 1 is arranged in a spiral, U-shaped or S-shaped layout.

[0034] The working process of the combined refrigeration system based on the elastocaloric and piezocaloric effects of the present invention is as follows:

[0035] At the beginning of the refrigeration cycle, first close the high-pressure valves 3 at both ends of the elastocaloric and piezocaloric combined refrigeration element 1 to seal a section of heat exchange fluid.

[0036] Close the pressure relief valve 7, turn on the hydraulic pump 5, so that the hydraulic oil flows from the hydraulic oil tank 8 into the piston cylinder 6, and then push the piston to pressurize the elastocaloric and piezocaloric combined refrigeration element 1 to the designed pressure value, causing the double-layer pipeline to expand; at this time, the polymer material 101 in the inner layer of the pipeline heats up due to the pressure conducted by the heat exchange fluid and the binding force of the shape memory alloy braided layer 102 acting in the opposite direction; the alloy filaments or strips in the shape memory alloy braided layer 102 on the outer layer of the pipeline are stretched under the action of tension and heat up.

[0037] Keep the pressure value unchanged, open the damper 10 and the fan 11, let the air at room temperature flow into the insulation box 9, and take the heat generated by the pressure out to the external environment. At this time, the temperature of the elastic heat and pressure heat combined refrigeration element 1 gradually decreases.

[0038] When the temperature of the elastic and pressure-heating combined refrigeration element 1 approaches room temperature, the damper 10 and the fan 11 are closed to isolate the thermal insulation box from the external room temperature environment. Then the pressure relief valve 7 is opened to quickly reduce the pressure inside the elastic and pressure-heating combined refrigeration element 1 to room pressure; at this time, the double-layer pipe contracts, the polymer material 101 of the inner layer of the pipe cools down due to pressure relief, and the shape memory alloy braided layer 102 of the outer layer of the pipe cools down due to unloading.

[0039] Open the high-pressure valve 3 to connect the two ends of the elastic and pressure combined refrigeration element 1 with the cold-end heat exchanger 2 to form a heat exchange circuit; turn on the circulating water pump 4 to drive the heat exchange fluid to circulate in the heat exchange circuit, and then carry the cold energy generated by the pressure relief to the cold-end heat exchanger 2, so that the temperature of the cold-end heat exchanger 2 drops and a cooling effect is produced.

[0040] When the temperature of the elastic and pressure-heating combined refrigeration element 1 approaches the temperature of the cold-end heat exchanger 2, the circulating water pump 4, the high-pressure valve 3 and the pressure relief valve 7 are closed, and the hydraulic pump 5 is opened, thereby starting the next refrigeration cycle.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A combined refrigeration system based on elasto-caloric and pressure-caloric effects, It is characterized in that It includes elastic and pressure combined refrigeration elements, cold end heat exchanger, high pressure valve, hydraulic pump, piston cylinder and circulating water pump, among which: A high-pressure valve is arranged between the elastic-heat and pressure-heat combined refrigeration element and the cold-end heat exchanger, the high-pressure end of the hydraulic pump is connected to the elastic-heat and pressure-heat combined refrigeration element via a piston cylinder, a pressure relief valve is arranged between the high-pressure end and the low-pressure end of the hydraulic pump, the low-pressure end of the hydraulic pump is connected to the hydraulic oil tank, and a circulating water pump is arranged between the high-pressure valve and the cold-end heat exchanger; The elastic-caloric and pressure-caloric combined refrigeration element is a double-layer pipeline, including a polymer material inner layer and a shape memory alloy braided layer. The polymer material inner layer has a pressure-caloric effect; the shape memory alloy braided layer has an elastic-caloric effect.

2. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The liquid inlet and the liquid outlet of the elastic-heat and pressure-heat combined refrigeration element are respectively connected to the liquid outlet and the liquid inlet of the cold end heat exchanger through two high-pressure valves.

3. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 2, It is characterized in that The two high-pressure valves are opened or closed synchronously under the control of electrical signals; in the closed state, both ends of the elastic-thermal and pressure-thermal combined refrigeration element are closed, and its internal space becomes a pressure vessel; in the open state, the elastic-thermal and pressure-thermal combined refrigeration element is connected to the cold-end heat exchanger, thereby forming a heat exchange circuit.

4. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The hydraulic pump is used to apply pressure to the elastic-heat and pressure-heat combined refrigeration element when the high-pressure valve is closed.

5. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The piston cylinder connects the elastic-heat and pressure-heat combined refrigeration element and the high-pressure end of the hydraulic pump, and is used for transmitting pressure and isolating the hydraulic oil and the heat exchange fluid.

6. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The circulating water pump is used to drive the heat exchange fluid to circulate in the heat exchange circuit when the high-pressure valve is open, and carry the cold energy generated by the pressure relief to the cold-end heat exchanger.

7. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that An insulation box is arranged outside the elastic heating and pressure heating combined refrigeration element, and the insulation box is provided with a plurality of air doors, at least one of which is connected to a fan to blow air into the insulation box, and the remaining air doors are used for ventilation of the insulation box.

8. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The material of the inner layer of the polymer material is polyethylene, polypropylene, polyurethane, polytetrafluoroethylene, polydimethylsiloxane, natural rubber, nitrile rubber, silicone rubber or ethylene-vinyl acetate copolymer.

9. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The material of the shape memory alloy braided layer is Ni-Ti alloy.

10. The combined refrigeration system based on elastic caloric and pressure caloric effect according to claim 1, It is characterized in that The elastic heat and pressure heat combined refrigeration elements are arranged in a spiral shape, a U shape or an S shape.

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