Laser heat management system adopting two-stage phase change cold storage and management method thereof

Abstract

The invention relates to the technical field of laser heat management, in particular to a laser heat management system adopting two-stage phase change cold storage and a management method of the laser heat management system, which can improve the cold storage density by utilizing the difference of the cold storage density and the phase change temperature of a phase change material. According to the system, the regenerator is designed by adopting a high-cold-accumulation-density phase-change material to replace a cold water tank, so that the size of the system is greatly reduced; in addition, the phase change temperature of the phase change cold storage material is high and higher than that of traditional sensible heat cold storage, the pressure of the evaporator and the compressor is reduced, and the efficiency of the refrigerating system at the high temperature is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser thermal management, and in particular to a laser thermal management system adopting two-stage phase change cold storage and a management method thereof. Background Art

[0002] The electro-optical conversion efficiency of lasers is usually 20% to 30%, and they generate a lot of heat during the working cycle. The cooling system required to dissipate such a large amount of heat in a short period of time is very large. There are currently a variety of laser thermal management solutions and possible technologies, such as phase change energy storage technology, loop heat pipe technology, enhanced heat exchange technology, etc.

[0003] The application of phase change heat storage technology can effectively deal with the impact of high-power laser heat flow on thermal management systems. Phase change heat storage technology has been promoted and used in the fields of solar energy utilization, power peak shaving, waste heat recovery and building materials, and there are many application examples in the field of spacecraft. Phase change materials have the characteristics of isothermal phase change and large latent heat of phase change. Applying phase change material heat storage technology to vehicle thermal management systems can provide thermal buffering and storage between thermal loads and terminal heat sinks, which can effectively alleviate the thermal impact of laser thermal loads on airborne thermal management systems.

[0004] Considering the characteristics of lasers such as short working time and instantaneous generation of a large amount of waste heat, their thermal management system is suitable for the use of high cold storage density phase change energy storage technology. That is, when the laser is working, the instantaneous peak heat load it generates is stored in whole or in part in the phase change material through some heat transfer method, and then the heat is transferred to the atmosphere through the refrigeration cycle system and the air circulation system during the remaining mission stages.

[0005] Secondly, laser cooling also requires high temperature control accuracy, such as the inlet water temperature requirement of 20-27°C, which also places high demands on temperature control. However, the liquid cooling sensible heat storage solution currently widely used in the market has a low cold storage density, low cold storage temperature, and low cooling efficiency in high temperature environments. Summary of the invention

[0006] In view of this, the present invention provides a laser thermal management system using two-stage phase change cold storage and a management method thereof, which can utilize the difference between the cold storage density and the phase change temperature of the phase change material to improve the cold storage density.

[0007] To achieve the above-mentioned purpose, the present invention provides a laser thermal management system using two-stage phase change cold storage, including a laser, a first water pump, a proportional control valve, a PTC heater, a phase change cold storage, a second water pump, an evaporator, an expansion valve, a condenser, a compressor, a radiator and a fan; wherein one end of the first water pump is connected to the laser, and the other end is connected to the proportional control valve; the laser is connected in parallel with the PTC heater, the phase change cold storage, and the evaporator, the proportional control valve is connected to the first water pump, the PTC heater, the phase change cold storage and the second water pump, the condenser output is connected to the expansion valve, the expansion valve is connected to the evaporator, the evaporator is connected to the compressor, the compressor output is connected to the condenser input, and the fan is arranged next to the condenser.

[0008] Among them, the phase change cold storage device is a double-flow two-stage phase change plate-fin cold storage device, including an inlet water chamber, a double-flow water chamber, an outlet water chamber, a primary phase change and a secondary phase change. The double-flow two-stage phase change plate-fin cold storage device is provided with an inlet and an outlet.

[0009] Among them, the outlet water chamber is arranged in the primary phase change, the primary phase change includes a primary phase change core and a primary phase change material filling port; the secondary phase change includes a secondary phase change core and a secondary phase change material filling port; the temperature of the primary phase change material is 15-20°C; the temperature of the secondary phase change material is 5-10°C.

[0010] Among them, the plate-fin cold storage device adopts rectangular fins made of aluminum alloy, the phase change cold storage device is placed vertically, and water chambers are respectively arranged at the top and bottom of the phase change cold storage device.

[0011] Among them, the system is a closed cooling system, and a pressure valve is turned on the upper part of the water chamber of the phase change cold storage device. The pressure valve ensures that the system is not over-pressurized.

[0012] The present invention also provides a management method for a laser thermal management system using a two-stage phase change cold storage, comprising the following steps:

[0013] Laser startup preparation stage: When the ambient temperature is between -40 and +23°C, the proportional control valve switches to the PTC heater branch, the first water pump works, the coolant is heated by the PTC heater, and flows through the laser until the coolant at the laser outlet is preheated to 25±2°C, and the preheating stops; then the refrigeration cycle works, and the second water pump and the first water pump also work until the outlet temperature of the phase change regenerator drops below 16°C;

[0014] After the laser is turned on: the first water pump works, the laser heats up and the fluid temperature rises, the flow on the upper side of the proportional control valve decreases, and the flow on the right side increases. The temperature of the coolant rises after the laser heats up; the refrigeration cycle transfers the heat of the evaporator to the condenser, and the fan rotates to take away the heat;

[0015] After the laser is turned off: the first water pump is turned off, the right side of the proportional control valve is turned on, and the second water pump works to transfer heat from the cold storage to the evaporator until the outlet temperature of the cold storage is lower than 16°C. The refrigeration cycle transfers the heat from the evaporator to the condenser, and the fan rotates to take away the heat.

[0016] Beneficial effects:

[0017] 1. The system of the present invention adopts high cold storage density phase change material to design the cold storage device instead of the cold water tank, which greatly reduces the system volume; in addition, the phase change temperature of the phase change cold storage material is higher than that of the traditional sensible heat cold storage, which reduces the pressure of the evaporator and the compressor and improves the efficiency of the refrigeration system at high temperature.

[0018] 2. The system of the present invention is a closed cooling system. A pressure valve is installed on the upper part of the water chamber of the phase change cold storage device to ensure that the system is not over-pressurized.

[0019] 3. In the system of the present invention, the cold storage device uses two solid-liquid phase change materials as cold storage media. To ensure the efficiency of the refrigeration cycle, the temperature of the primary phase change material is 15-20°C, such as pure substances such as n-tetradecane, octanoic acid, polyethylene glycol and their eutectic mixtures. The temperature of the secondary phase change material is 5-10°C, such as n-dodecane. The cold storage material can provide continuous cooling in a short time and play a role in stabilizing the cooling output.

[0020] 4. The cold storage device in the system of the present invention adopts plate-fin type, aluminum alloy material, and rectangular fins. The heat storage and cold storage devices are placed vertically to prevent the contact thermal resistance with the metal wall caused by shrinkage during the solidification process. Water chambers are respectively set at the top and bottom of the phase change cold storage device to distribute the coolant.

[0021] 5. In the system of the present invention, since the evaporator temperature is high, about 10°C, the requirements for the compressor and refrigerant are low, and the refrigeration cycle can operate in the high-efficiency area. Even if the ambient temperature reaches 50°C, the refrigeration cycle refrigerant can be R134 and R134a, and the compressor can be a conventional scroll compressor.

[0022] 6. The method of the present invention is implemented based on the system of the present invention, and a high cold storage density phase change material is used to design a cold storage device to replace the cold water tank, which greatly reduces the volume of the system; in addition, the phase change temperature of the phase change cold storage material is relatively high, which is higher than that of traditional sensible heat cold storage, reducing the pressure of the evaporator and the compressor and improving the efficiency of the refrigeration system at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the system embodiment of the present invention.

[0024] Figure 2 Schematic diagram of the interface and water chamber of the dual-flow two-stage phase-change plate-fin cold storage device of the system embodiment of the present invention.

[0025] Figure 3It is a schematic diagram of a dual-process two-stage phase change cold storage and a single-stage phase change in an embodiment of the system of the present invention.

[0026] Figure 4 It is a schematic diagram of a dual-process two-stage phase change cold storage and two-stage phase change in an embodiment of the system of the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0028] The embodiment of the present invention provides a laser thermal management system using two-stage phase change cold storage, such as Figure 1 As shown, it includes a laser, a first water pump, a proportional control valve, a PTC heater, a phase change cold storage device, a second water pump, an evaporator, an expansion valve, a condenser, a compressor, a radiator and a fan; wherein, one end of the first water pump is connected to the laser, and the other end is connected to the proportional control valve; the laser is connected in parallel with the PTC heater, the phase change cold storage device, and the evaporator, the proportional control valve is connected to the first water pump, the PTC heater, the phase change cold storage device and the second water pump, the condenser output is connected to the expansion valve, the expansion valve is connected to the evaporator, the evaporator is connected to the compressor, the compressor output is connected to the condenser input, and the fan is arranged next to the condenser.

[0029] The phase change cold storage device is a double-flow two-stage phase change plate-fin cold storage device, and its interface is connected to the water chamber as shown in FIG. Figure 2 As shown, the double-flow two-stage phase-change plate-fin cold storage device includes an inlet water chamber 1, a double-flow water chamber 2, an outlet water chamber 3, a primary phase change and a secondary phase change, and the double-flow two-stage phase-change plate-fin cold storage device is provided with an inlet 11 and an outlet 12. In the system of the present invention, a cold storage device is designed using a high cold storage density phase change material to replace a cold water tank, which greatly reduces the volume of the system; the phase change temperature of the phase change cold storage material is relatively high, which is higher than that of traditional sensible heat cold storage, reduces the pressure of the evaporator and the compressor, and improves the efficiency of the refrigeration system at high temperatures.

[0030] Furthermore, the primary phase transition is as follows Figure 3 As shown, the outlet water chamber 3 is arranged in the primary phase change, and the primary phase change includes a primary phase change core 31 and a primary phase change material filling port 32; the secondary phase change is as shown in Figure 4 As shown, the secondary phase change includes a secondary phase change core 41 and a secondary phase change material filling port 42. In this embodiment, the cold storage device uses two solid-liquid phase change materials as cold storage media. To ensure the efficiency of the refrigeration cycle, the temperature of the primary phase change material is 15-20°C, such as pure substances such as n-tetradecane, octanoic acid, polyethylene glycol and their eutectic mixtures. The temperature of the secondary phase change material is 5-10°C, such as n-dodecane. The cold storage material can provide continuous cooling in a short time and play a role in stabilizing the cooling output.

[0031] Furthermore, the plate-fin refrigerant uses rectangular fins made of aluminum alloy, and the phase change refrigerant is placed vertically to prevent thermal resistance with the metal wall caused by shrinkage during the solidification process. Water chambers are respectively arranged at the top and bottom of the phase change refrigerant to distribute the coolant.

[0032] In addition, since the evaporator temperature is high, about 10°C, the requirements for the compressor and refrigerant are low, and the refrigeration cycle can operate in the high-efficiency area, even if the ambient temperature reaches 50°C. The refrigeration cycle refrigerant can use R134 and R134a, and the compressor can be a conventional scroll compressor.

[0033] Furthermore, the system of the present invention is a closed cooling system, and a pressure valve is screwed on the upper part of the water chamber of the phase change cold storage device, and the pressure valve ensures that the system is not over-pressurized.

[0034] The present invention also provides a management method for a laser thermal management system using a two-stage phase change cold storage, comprising the following steps:

[0035] Laser startup preparation stage: When the ambient temperature is between -40 and +23°C, the proportional control valve switches to the PTC heater branch, the first water pump works, the coolant is heated by the PTC heater, flows through the laser, and the coolant at the laser outlet is preheated to 25±2°C, and the preheating stops. Then the refrigeration cycle works, and the second water pump and the first water pump also work until the outlet temperature of the phase change regenerator drops below 16°C.

[0036] After the laser is turned on: the first water pump works, the laser heats up and the fluid temperature rises, the flow on the upper side of the proportional control valve decreases, and the flow on the right side increases. The temperature of the coolant rises after the laser heats up. The refrigeration cycle transfers the heat of the evaporator to the condenser, and the fan rotates to take the heat away. The speed of the fan is determined according to the outlet temperature of the hot side of the cold storage, and the goal is to make the outlet temperature of the hot side of the cold storage lower than 16°C.

[0037] After the laser is turned off: the first water pump is turned off, the right side of the proportional control valve is turned on, and the second water pump works to transfer heat from the cold storage to the evaporator until the outlet temperature of the cold storage is lower than 16°C. The refrigeration cycle transfers the heat of the evaporator to the condenser, and the fan rotates to take away the heat. The speed of the fan is determined according to the outlet temperature of the hot side of the cold storage, and the goal is to make the outlet temperature of the hot side of the cold storage lower than 16°C.

[0038] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser thermal management system using two-stage phase change cold storage, characterized in that: It includes a laser, a first water pump, a proportional control valve, a PTC heater, a phase-change cold storage device, a second water pump, an evaporator, an expansion valve, a condenser, a compressor, a radiator and a fan; wherein one end of the first water pump is connected to the laser, and the other end is connected to the proportional control valve; the laser is connected in parallel with the PTC heater, the phase-change cold storage device and the evaporator, the proportional control valve is connected to the first water pump, the PTC heater, the phase-change cold storage device and the second water pump, the condenser output is connected to the expansion valve, the expansion valve is connected to the evaporator, the evaporator is connected to the compressor, the compressor output is connected to the condenser input, and the fan is arranged next to the condenser.

2. The system according to claim 1, characterized in that The phase change cold storage device is a double-flow two-stage phase change plate-fin cold storage device, comprising an inlet water chamber, a double-flow water chamber, an outlet water chamber, a primary phase change and a secondary phase change. The double-flow two-stage phase change plate-fin cold storage device is provided with an inlet and an outlet.

3. The system according to claim 2, characterized in that The outlet water chamber is arranged in the primary phase change, the primary phase change includes a primary phase change core and a primary phase change material filling port; the secondary phase change includes a secondary phase change core and a secondary phase change material filling port; the temperature of the primary phase change material is between 15 and 20°C; the temperature of the secondary phase change material is between 5 and 10°C.

4. The system according to claim 2 or 3, characterized in that The plate-fin cold storage device uses rectangular fins made of aluminum alloy. The phase change cold storage device is placed vertically, and water chambers are set at the top and bottom of the phase change cold storage device respectively.

5. The system according to claim 4, characterized in that The system is a closed cooling system. A pressure valve is installed on the upper part of the water chamber of the phase change cold storage device to ensure that the system is not over-pressurized.

6. A management method for a laser thermal management system using two-stage phase change cold storage as claimed in any one of claims 1 to 5, comprising the following steps: Laser startup preparation stage: When the ambient temperature is between -40 and +23°C, the proportional control valve switches to the PTC heater branch, the first water pump works, the coolant is heated by the PTC heater, and flows through the laser until the coolant at the laser outlet is preheated to 25±2°C, and the preheating stops; then the refrigeration cycle works, and the second water pump and the first water pump also work until the outlet temperature of the phase change regenerator drops below 16°C; After the laser is turned on: the first water pump works, the laser heats up and the fluid temperature rises, the flow on the upper side of the proportional control valve decreases, and the flow on the right side increases. The temperature of the coolant rises after the laser heats up; the refrigeration cycle transfers the heat of the evaporator to the condenser, and the fan rotates to take away the heat; After the laser is turned off: the first water pump is turned off, the right side of the proportional control valve is turned on, and the second water pump works to transfer heat from the cold storage to the evaporator until the outlet temperature of the cold storage is lower than 16°C. The refrigeration cycle transfers the heat from the evaporator to the condenser, and the fan rotates to take away the heat.

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