Electric card cooling system with independent heat conduction branch and heat recovery capability

Abstract

An electric card refrigeration system with independent heat conduction branches and heat recovery capability includes two electric card refrigeration devices, a fluid drive device, a condenser, and an evaporator. The fluid drive device and the condenser are sequentially arranged between the first output and first input ends of the first and second electric card devices, and the evaporator is arranged between the second output and second input ends of the first and second electric card devices. The two electric card refrigeration devices alternately apply and remove an electric field, allowing the evaporator to continuously cool while heat is released to the outside through the condenser. This invention significantly improves the heat exchange efficiency and operating efficiency of the refrigeration system and avoids the limitation of a single electric card refrigeration system that cannot achieve continuous cooling during the application and removal of the electric field.

Description

Technical Field

[0001] The present invention relates to a technology in the field of refrigeration, specifically an electric card refrigeration system with an independent heat conduction branch and heat recovery capability. Background Art

[0002] Existing single-set electrocaloric cooling systems require alternating application and removal of the electric field, and alternate contact between the material and the heat sink to complete the refrigeration cycle. This is intermittent cooling rather than continuous cooling, as shown in Rujun Ma et al. Science, 357 (2017) 1130-1134 (Highly Efficient Electrocaloric Cooling with Electrostatic Actuation). Consequently, their use is significantly limited. In existing electrocaloric cooling systems, hot and cold fluids circulate in the same branch, potentially resulting in significant cooling losses. Furthermore, most existing solid-state electrocaloric effect-based air conditioning systems do not utilize a regenerative heat recovery process. This means that the electrocaloric material, about to be de-energized, is not pre-cooled by the cold fluid from the cooling heat exchanger through a suitable phase adjustment of the electric field and fluid motion, and then further cooled by the electrocaloric cooling effect. Furthermore, the electrocaloric material, about to be energized, is not pre-heated by the hot fluid from the heating heat exchanger, and then further heated by the electrocaloric heating effect, thereby expanding the temperature range of the electrocaloric cooling cycle. Summary of the Invention

[0003] In response to the aforementioned shortcomings of the prior art, the present invention proposes an electrocaloric refrigeration system with an independent heat conduction branch and heat recovery capability. This significantly improves the heat exchange efficiency and operating efficiency of the refrigeration system and avoids the limitation of a single electrocaloric refrigeration system that cannot achieve continuous cooling during the application and removal of the electric field. The present invention achieves a heat recovery process by phasing the electric field and fluid motion. This allows the electrocaloric material to be preheated by the hot fluid exiting the condenser and then further heated up by the electrocaloric heating effect, while the electrocaloric material to be removed from the evaporator is precooled by the cold fluid exiting the evaporator and then further cooled by the electrocaloric cooling effect. This allows the electrocaloric refrigeration system to operate over a temperature span greater than the adiabatic temperature change of the electrocaloric material.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to an electric card refrigeration system with an independent heat conduction branch and maintaining heat recovery capability, comprising: two electric card refrigeration devices, a fluid drive device, a condenser and an evaporator, wherein: the fluid drive device and the condenser are arranged in sequence between the first output end and the first input end of the first and second electric card devices, and the evaporator is arranged between the second output end and the second input end of the first and second electric card devices. The two electric card refrigeration devices alternately apply and remove the electric field, so that the evaporator continues to cool while the heat is released to the outside through the condenser.

[0006] The fluid drive device and condenser are specifically arranged in the first common section, that is, between the output ends of the two electric card refrigeration devices and the control module; the evaporator is specifically arranged in the second common section, that is, between the control module and the input ends of the two electric card refrigeration devices; the first output end of the first electric card refrigeration device and the first common section are the first branch, the first output end of the second electric card refrigeration device and the first common section are the second branch, the second output end of the first electric card refrigeration device and the second common section are the third branch, and the second output end of the second electric card refrigeration device and the second common section are the fourth branch.

[0007] The independent heat conduction branches mean that when the first electric card cooling device is in the electric field application process and the second electric card cooling device is in the electric field removal process, the first branch is the heating branch and the fourth branch is the cooling branch. When the first electric card cooling device is in the electric field removal process and the second electric card cooling device is in the electric field application process, the second branch is the heating branch and the third branch is the cooling branch. The four branches do not affect each other, so there is no irreversible energy loss.

[0008] The electrocaloric refrigeration device includes: electrocaloric material, electrodes and wires for applying and removing electric fields to the electrocaloric material. The refrigeration effect is achieved by changing the polarization entropy of the electrocaloric material through the external electric field acting on the electrocaloric refrigeration device.

[0009] The sides of the two electric card refrigeration devices are both wrapped with an insulation layer, and baffles are provided at both ends of the electric card refrigeration devices for controlling the circulation or stationary state of the working fluid therein.

[0010] The electrocaloric material is but not limited to PbZr 0.95 Ti 0.05 Materials with electrocaloric effect such as O3, (Ba, Sr)TiO3 or P(VDF-TrFE-CFE).

[0011] The electric card refrigeration system further includes a control module connected to the two electric card refrigeration devices respectively, and the control module includes: a high-voltage unit and a signal control unit, wherein: the signal control unit controls the high-voltage unit to apply an electric field to the first electric card refrigeration device while removing the electric field from the second electric card refrigeration device; or to remove the electric field from the first electric card refrigeration device while applying an electric field to the second electric card refrigeration device.

[0012] The present invention relates to a control method based on the above-mentioned electric card refrigeration system. When the first electric card refrigeration device is in the electric field application process, the second electric card refrigeration device is in the electric field removal process, the first branch and the fourth branch are in operation, and the second branch and the third branch are disconnected. After the heat exchange of the system reaches a balanced state, before the working state of the switching control module is switched to put the second electric card refrigeration device in the electric field application process and the first electric card refrigeration device in the electric field removal process, the fluid coming out of the evaporator is pre-cooled by the fluid driving device to reduce the temperature of the first electric card refrigeration device, and the fluid coming out of the condenser is preheated to increase the temperature of the second electric card refrigeration device (the phase of the electric field and the fluid movement is adjusted, and the baffles at both ends of the first electric card refrigeration device and the second electric card refrigeration device are closed to put them in a static state). Then, the working state of the control module is switched, so that the first electric card refrigeration device is in the electric field removal process and the second electric card refrigeration device is in the electric field application process (the baffles at both ends of the first electric card refrigeration device and the second electric card refrigeration device are opened to allow the working fluid to flow in the electric card refrigeration device), the second branch and the third branch are working, and the first branch and the fourth branch are disconnected; then, after the system heat exchange reaches a balanced state, and before the working state of the control module is switched so that the first electric card refrigeration device is in the electric field application process and the second electric card refrigeration device is in the electric field removal process, the fluid coming out of the condenser is preheated by the fluid driving device to the first electric card refrigeration device to increase its temperature, and the fluid coming out of the evaporator is precooled to the second electric card refrigeration device to reduce its temperature (the phase of the electric field and the fluid movement is adjusted, and the baffles at both ends of the first electric card refrigeration device and the second electric card refrigeration device are closed to put them in a static state).

[0013] Technical Effects

[0014] The present invention realizes the heat recovery process by phase matching of the electric field and the fluid movement, that is, the colder fluid coming out of the evaporator is pre-cooled by the electrocaloric refrigeration device with voltage applied, so that it can start cooling from a lower temperature before the voltage is removed; the hotter fluid coming out of the condenser is pre-heated by the electrocaloric refrigeration device after the voltage is removed, so that it can start heating from a higher temperature before the voltage is applied; the independently operating cooling and heating branches do not affect each other, which can reduce the irreversible energy loss of the system; in addition, during the application and removal of the electric field, the temperature gradient direction inside the electrocaloric material is the same as the temperature gradient direction of the heat exchange fluid, thereby improving the working efficiency of the refrigeration system while realizing a continuous refrigeration capacity with a large temperature span (surpassing the adiabatic temperature change of the electrocaloric material). BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the system of the present invention;

[0016] Figure 2-Figure 5 This is a schematic diagram of the working state of the present invention;

[0017] In the figure: 1 first electric card refrigeration device, 2 second electric card refrigeration device, 3 control module, 4 fluid driving device, 5 condenser, 6 evaporator, 7 first valve, 8 second valve, 9 third valve, 10 fourth valve, 11 first branch, 12 second branch, 13 third branch, 14 fourth branch, 15 first common section, 16 second common section, 17 first insulation layer, 18 second insulation layer, 19 first baffle, 20 second baffle;

[0018] Figure 6 It is the temperature entropy diagram of the refrigeration cycle of the embodiment. DETAILED DESCRIPTION

[0019] like Figure 1-Figure 5 As shown, an electric card refrigeration system with heat recovery capability and continuous cooling according to this embodiment includes: a first electric card refrigeration device 1, a second electric card refrigeration device 2, a control module 3 for controlling the first electric card refrigeration device 1 and the second electric card refrigeration device 2, a fluid drive device 4, a condenser 5, and a first branch 11 and a second branch 12 connecting the first electric card refrigeration device 1, the second electric card refrigeration device 2 and the condenser 5, an evaporator 6, and a third branch 13 and a fourth branch 14 connecting the first electric card refrigeration device 1, the second electric card refrigeration device 2 and the evaporator 6, wherein: a first valve 7 and a second valve 8 are provided at both ends of a first common section 15, a third valve 9 and a fourth valve 10 are provided at both ends of a second common section 16, a first insulation layer 17 is provided on a side of the first electric card refrigeration device 1, a second insulation layer 18 is provided on a side of the second electric card refrigeration device 2, a first baffle 19 is provided at both ends of the first electric card refrigeration device 1, and a second baffle 20 is provided at both ends of the second electric card refrigeration device 2;

[0020] like Figure 2 As shown, the flow state of the working fluid in the electric card refrigeration device when the first electric card refrigeration device is in the state of applying the electric field and the second electric card refrigeration device is in the state of removing the electric field; Figure 3 As shown, before the switching control module is in operation and the second electric card refrigeration device is in the process of applying the electric field and the first electric card refrigeration device is in the process of removing the electric field, the fluid coming out of the evaporator is used to precool the first electric card refrigeration device to reduce its temperature, and the fluid coming out of the condenser is used to preheat the second electric card refrigeration device to increase its temperature. Figure 4 As shown, the flow state of the working fluid in the electric card refrigeration device when the first electric card refrigeration device is in the state of removing the electric field and the second electric card refrigeration device is in the state of applying the electric field; Figure 5 As shown, before the working state of the switching control module puts the first electric card refrigeration device in the electric field application process and the second electric card refrigeration device in the electric field removal process, the fluid coming out of the condenser is used to preheat the first electric card refrigeration device to increase its temperature, and the fluid coming out of the evaporator is used to precool the second electric card refrigeration device to reduce its temperature.

[0021] When the first electric card refrigeration device 1 is in the process of applying voltage, the second electric card refrigeration device 2 is in the process of removing voltage, the first valve 7, the second valve 8, the third valve 9 and the fourth valve 10 are in a working state, the first branch 11 and the fourth branch 14 are working, the second branch 12 and the third branch 13 are disconnected, and the first electric card cycle is in operation; the temperature of the first electric card refrigeration device 1 increases, and the temperature of the second electric card refrigeration device 2 decreases, the fluid driving device 4 drives the flow of the working fluid to transfer heat, the evaporator 6 works to absorb heat from the outside, and the condenser 5 works to release heat to the outside, such as Figure 2 shown.

[0022] After the system reaches thermal equilibrium, before the control module 3 switches the working state, the baffles 19 at both ends of the first electric card refrigeration device 1 and the baffles 20 at both ends of the second electric card refrigeration device are closed, and the hot working fluid coming out of the condenser 5 is used by the fluid driving device 4 to preheat the second electric card refrigeration device 2 to increase its temperature, and the cold working fluid coming out of the evaporator 6 is used to precool the first electric card refrigeration device 1 to reduce its temperature. Figure 3 shown.

[0023] The control module 3 switches the working state, so that the second electric card refrigeration device 2 is in the voltage application process and the first electric card refrigeration device 1 is in the voltage removal process, the first valve 7, the second valve 8, the third valve 9 and the fourth valve 10 are in another working state, the second branch 12 and the third branch 13 are working, the first branch 11 and the fourth branch 14 are disconnected, and the baffles 19 at both ends of the first electric card refrigeration device 1 and the baffles 20 at both ends of the second electric card refrigeration device are opened. At this time, the second electric card cycle is in operation; the temperature of the first electric card refrigeration device 1 is further reduced on the basis of pre-cooling, and the temperature of the second electric card refrigeration device 2 is further increased on the basis of preheating, the fluid driving device 4 drives the flow of the working fluid to transfer heat, the evaporator 6 continues to work to absorb heat from the outside, and the condenser 5 continues to work to release heat to the outside, such as Figure 4 shown.

[0024] After the system reaches thermal equilibrium, before the control module 3 switches the working state again, the baffles 19 at both ends of the first electric card refrigeration device 1 and the baffles 20 at both ends of the second electric card refrigeration device are closed, and the hot working fluid coming out of the condenser 5 is used by the fluid driving device 4 to preheat the first electric card refrigeration device 1 to increase its temperature, and the cold working fluid coming out of the evaporator 6 is used to precool the second electric card refrigeration device 1 to reduce its temperature. Figure 5 shown.

[0025] By alternately applying and removing the electric field between the first electric card refrigeration device 1 and the second electric card refrigeration device 2, the first and fourth branches (11 and 14) and the second and third branches (12 and 13) are alternately operated and disconnected, so that the condenser 5 and the evaporator 6 can continue to work, that is, the refrigeration equipment continues to cool. The refrigeration system is operated along the Figure 6 The abcdefa path similar to the reverse Brayton cycle shown completes the refrigeration cycle, and the temperature span achieved is greater than the adiabatic temperature change of the electrocaloric material; similarly, heat is continuously released to the outside.

[0026] After finite element simulation, the voltage amplitude applied to the first electric card refrigeration device 1 and the second electric card refrigeration device 2 by the control module 3 is 100MV / m, and a single electric card refrigeration device consists of 12 layers of 100μm thick Ba 0.2 Zr 0.8 When the system is composed of TiO3 / P (VDF-TrFE-CFE) composite film, the cooling power density of the system can reach 32W / cm when the temperature span of the hot and cold ends of the system is 10K and the operating frequency is 4Hz. 3 , while the COP is greater than 5. Compared with the existing technology, this device achieves a continuous refrigeration process under a larger temperature span through the heat recovery process, and its refrigeration power density is increased by about 400%.

[0027] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. An electric card refrigeration system with an independent heat conduction branch and heat recovery capability, characterized in that: include: Two electric card refrigeration devices, a fluid drive device, a condenser, and an evaporator, wherein: the fluid drive device and the condenser are sequentially arranged between the first output end and the first input end of the first and second electric card devices, and the evaporator is arranged between the second output end and the second input end of the first and second electric card devices. The two electric card refrigeration devices alternately apply and remove the electric field, so that the evaporator continues to cool while the heat is released to the outside through the condenser; The fluid drive device and condenser are specifically arranged in the first common section, that is, between the output ends of the two electric card refrigeration devices and the control module; the evaporator is specifically arranged in the second common section, that is, between the control module and the input ends of the two electric card refrigeration devices; the first branch is between the first output end of the first electric card refrigeration device and the first common section, the second branch is between the first output end of the second electric card refrigeration device and the first common section, the third branch is between the second output end of the first electric card refrigeration device and the second common section, and the fourth branch is between the second output end of the second electric card refrigeration device and the second common section. The independent heat conduction branch means that when the first electric card refrigeration device is in the electric field application process and the second electric card refrigeration device is in the electric field removal process, the first branch is the heating branch and the fourth branch is the cooling branch; when the first electric card refrigeration device is in the electric field removal process and the second electric card refrigeration device is in the electric field application process, the second branch is the heating branch and the third branch is the cooling branch.

2. The electric card refrigeration system with independent heat conduction branch and heat recovery capability according to claim 1 is characterized in that: The electrocaloric refrigeration device comprises: electrocaloric material, electrodes and wires for applying and removing an electric field to the electrocaloric material. The refrigeration effect is achieved by changing the polarization entropy of the electrocaloric material through an external electric field acting on the electrocaloric refrigeration device. The sides of the two electric card refrigeration devices are both wrapped with an insulation layer, and baffles are provided at both ends of the electric card refrigeration devices for controlling the circulation or stationary state of the working fluid therein.

3. The electric card refrigeration system with independent heat conduction branch and heat recovery capability according to claim 1 is characterized in that: The electric card refrigeration system further includes a control module connected to the two electric card refrigeration devices respectively, and the control module includes: a high-voltage unit and a signal control unit, wherein: the signal control unit controls the high-voltage unit to apply an electric field to the first electric card refrigeration device while removing the electric field from the second electric card refrigeration device; or to remove the electric field from the first electric card refrigeration device while applying an electric field to the second electric card refrigeration device.

4. A control method for an electric card refrigeration system having an independent heat conduction branch and maintaining heat recovery capability based on any one of claims 1-3, characterized in that: When the first electric card refrigeration device is in the process of applying the electric field, the second electric card refrigeration device is in the process of removing the electric field, the first branch and the fourth branch are working, and the second branch and the third branch are disconnected; when the heat exchange of the system reaches a balanced state, before the working state of the switching control module is used to put the second electric card refrigeration device in the process of applying the electric field and the first electric card refrigeration device in the process of removing the electric field, the fluid coming out of the evaporator is pre-cooled to the first electric card refrigeration device to reduce its temperature, and the fluid coming out of the condenser is pre-heated to the second electric card refrigeration device to increase its temperature, that is, the phase of the electric field and the fluid movement is coordinated, and at the same time, the baffles at both ends of the first electric card refrigeration device and the second electric card refrigeration device are closed to make them in a static state, and then the working state of the control module is switched to put the first electric card refrigeration device in the process of removing the electric field The process makes the second electric card refrigeration device in the electric field application process, that is, the baffles at both ends of the first electric card refrigeration device and the second electric card refrigeration device are opened to allow the working fluid to flow in the electric card refrigeration device, the second branch and the third branch are working, and the first branch and the fourth branch are disconnected; then after the system heat exchange reaches a balanced state, and then in the working state of the switching control module, the first electric card refrigeration device is put into the electric field application process and the second electric card refrigeration device is put into the electric field removal process, the fluid coming out of the condenser is preheated by the fluid driving device to the first electric card refrigeration device to increase its temperature, and the fluid coming out of the evaporator is precooled to the second electric card refrigeration device to reduce its temperature, that is, the phase of the electric field and the fluid movement is adjusted, and at the same time, the baffles at both ends of the first electric card refrigeration device and the second electric card refrigeration device are closed to make them in a static state.

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