A method for adaptive correction of temperature difference in laser cooling system

Abstract

This invention belongs to the technical field of laser chiller control methods, and particularly relates to a laser chiller control temperature difference adaptive correction method. It includes the following steps: detecting laser operating parameters based on the flow rate-temperature difference method and calculating waste heat; based on the calculated waste heat, detecting the waste heat at the start of each laser operating cycle and plotting a waste heat change curve over time; selecting a heat balance line based on the change curve and calculating the control temperature difference; and adjusting the chiller's cooling capacity. This laser chiller control temperature difference adaptive correction method optimizes the chiller's cooling capacity output by using the laser's waste heat change as a condition, thereby optimizing the cooling water temperature circulation. It utilizes the cooling water's cooling capacity circulation to achieve water temperature balance optimization, reduce water temperature fluctuations, and determine the control temperature difference. This solution is simple, efficient, and highly practical, and can improve problems such as the mismatch between refrigeration and cooling demands in traditional chillers, thus improving system efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of laser cooling system control methods, and particularly relates to a laser cooling system control temperature difference adaptive correction method. Background Technology

[0002] During laser welding, cutting, and cleaning operations, the laser periodically generates a large amount of waste heat. To ensure stable operation of the laser, a cooling system is needed to cool it down, remove the waste heat, and keep the laser at a stable operating temperature.

[0003] Currently, laser cooling systems generally employ the temperature difference control method. The ultimate goal of this temperature control method is to keep the refrigerant temperature of the laser cooling system near the set temperature value T0. When the refrigerant temperature is lower than T0-ΔT, the cooling system is shut down; when the refrigerant temperature is higher than T0+ΔT, the cooling system is activated for cooling. The temperature difference ΔT is generally specified as a safe value based on a high-temperature alarm threshold. This is an interference-based and fuzzy coarse control method. The cooling power of this control method is often too high, leading to unnecessary energy consumption and over-cooling. In addition, the lag in the thermal cycle often results in blind cooling and a large amount of wasted energy in the cooling system based on this scheme, which is not conducive to the precise and efficient operation of the refrigerant. Summary of the Invention

[0004] The purpose of this invention is to provide a more effective and energy-efficient temperature difference control method, which provides accuracy in controlling the temperature difference and matching degree with the refrigeration cycle system, thereby reducing temperature fluctuations in the cooling system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for adaptive correction of temperature difference control in a laser cooling system includes the following steps:

[0007] S1. Calculate the waste heat Q by detecting the laser's operating parameters using the flow rate-temperature difference method:

[0008]

[0009] Where C refers to the specific heat capacity of the refrigerant, in J / (kg×℃); m refers to the refrigerant flow rate, in L / min; T back T represents the reflux temperature. out This refers to the cooling temperature, measured in °C.

[0010] S2. Based on the waste heat calculated in step S1, detect the waste heat after the laser's stable operating cycle begins, and plot the Qt curve of waste heat change over time; select the heat balance line Q = Qt based on the Qt curve. ave This causes the peak of the Qt change curve to coincide with the heat equilibrium line Q = Q.ave The trough of the cooling deficit area S3 and the Qt variation curve, and the heat balance line Q = Q ave The enclosed cold storage area S2 is equal;

[0011] Then there is

[0012] Where Q1 is the average waste heat value in the trough section of the Qt variation curve, in W;

[0013] Where Q2 is the average waste heat value of the peak segment on the Qt change curve, in W;

[0014] t1 is the time required for the Qt curve to reach its first peak;

[0015] t2 is the time required for the first peak of the Qt change curve to end;

[0016] t3 is the time required for the Qt curve to reach its first trough;

[0017] t4 is the time required for the first trough of the Qt change curve to end;

[0018] S3, Calculate and control temperature difference

[0019] The peak period refers to the time period when the waste heat value is within ±10% of the maximum waste heat value, and the trough period refers to the time period when the waste heat value is within ±10% of the minimum waste heat value.

[0020] Its beneficial effects are as follows:

[0021] The adaptive temperature difference correction method for laser cooling system proposed in this application optimizes the cooling capacity output of the cooling system by using the change in waste heat of the laser as a condition, thereby optimizing the refrigerant temperature cycle. It achieves temperature balance optimization by utilizing the cooling capacity cycle of the refrigerant, reducing temperature fluctuations, and determining the control temperature difference. This scheme is simple, efficient, and highly practical. It can improve the problem of mismatch between cooling and cooling demand in traditional cooling systems and improve system efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the modeling of waste heat changes in a laser. Detailed Implementation

[0023] The adaptive temperature difference correction method for laser cooling system control in this application is mainly used to optimize the temperature difference control parameters during the refrigeration system cycle control process, thereby controlling the cooling power output of the refrigeration system, suppressing the overcooling phenomenon of the refrigeration system, reducing unnecessary power output (loss), reducing system power consumption, and improving its stability. Its main principle is to optimize the cooling output of the refrigeration system based on the periodic waste heat output characteristics during the stable operation of the laser, so that it can operate continuously at a lower power than traditional refrigeration systems. It also utilizes the cooling capacity accumulated by the refrigeration system in the low waste heat production stage to make up for the insufficient cooling capacity in the high waste heat production stage. Combined with the refrigeration cycle, it realizes the functions of pre-cooling and cooling capacity buffering, thereby enhancing the uniformity and stability of the cooling capacity output of the refrigeration system, reducing the system control and output pressure, and reducing the number of high-load operation times of the compressor and the cycle system.

[0024] The following combination Figure 1 The specific working process of this invention is described below:

[0025] 1) First, detect the laser's operating parameters using the flow rate-temperature difference method, and calculate the waste heat. The formula for calculating waste heat is:

[0026]

[0027] Where C refers to the specific heat capacity of the refrigerant, measured in J / (kg×℃); m refers to the refrigerant flow rate, measured in L / min, which is the flow rate of the refrigerant output from the refrigeration system; T back T represents the return temperature, which is the temperature of the high-temperature refrigerant returning to the refrigeration system. out It refers to the cooling temperature, measured in °C, which is the temperature of the low-temperature refrigerant output from the refrigeration system.

[0028] 2) Based on the detected waste heat curve, select appropriate coordinates. Measure the waste heat calculated in step S1 after the laser's stable operating cycle begins, and plot the Qt curve showing the waste heat change over time. Select the heat balance line Q = Qt based on the Qt curve. ave This causes the peak of the Qt change curve to coincide with the heat equilibrium line Q = Q. ave The trough of the cooling deficit area S3 and the Qt variation curve, and the heat balance line Q = Q ave The enclosed cold storage area S2 is equal;

[0029] Then there is

[0030] Where Q1 is the average waste heat value in the trough section of the Qt variation curve, in W;

[0031] Where Q2 is the average waste heat value of the peak segment on the Qt change curve, in W;

[0032] t1 is the time required for the Qt curve to reach its first peak;

[0033] t2 is the time required for the first peak of the Qt change curve to end;

[0034] t3 is the time required for the Qt curve to reach its first trough;

[0035] t4 is the time required for the first trough of the Qt change curve to end;

[0036] S3, Calculate and control temperature difference

[0037] Those skilled in the art know that, in actual implementation, the actual waste heat output of the laser does not remain constant during the time period when it reaches the peak, but rather exhibits a slight fluctuation. Generally, the waste heat value during the peak period is within ±10% of the maximum waste heat value, and the waste heat value during the trough period is within ±10% of the minimum waste heat value.

[0038] In practical use, some of the heat generated by the laser during operation is directly dissipated into the air, while some is carried away by the refrigerant. The refrigeration system is mainly used to provide a stable refrigerant temperature to prevent it from becoming too high. Therefore, this application calculates the amount of waste heat carried away by the refrigerant from the laser by detecting the temperature difference before and after the refrigerant flow rate. Ideally, once the laser is running stably, the cooling capacity of the refrigeration system should match the amount of waste heat to ensure the stable operation of the low-temperature refrigerant. However, in reality, the heat generated by the laser and the cooling capacity of the refrigeration system are dynamically changing at different scales. Early refrigeration systems had limited heat exchange efficiency and immature refrigerant circulation heat exchange structures. To prevent the laser from being damaged by excessively high temperatures in the short term, a subcooling method was generally adopted, always providing more abundant cooling capacity to maintain the stable operation of the laser. Although this method is simple, it obviously leads to unnecessary cooling output and waste, while also increasing the power demand of the entire refrigeration system, making the system structure more complex, and decreasing the sensitivity of the temperature control of the entire system as the cooling capacity and total amount of refrigerant increase.

[0039] By applying the improved scheme of this application, unnecessary expansion of the cooling capacity output of the refrigeration system can be prevented. Based on the refrigerant heat exchange channel, the appropriate refrigeration power that can meet the requirements of waste heat treatment can always be provided, thereby reducing the output load of the refrigeration system, reducing the number of start-stop operations of the compressor and control system in the refrigeration system, simplifying the control scheme, and improving the effective utilization of refrigeration power.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for adaptive correction of temperature difference control in a laser cooling system, characterized in that, Includes the following steps: S1. Calculate the waste heat by detecting the laser's operating parameters using the flow rate-temperature difference method. : ； Where C refers to the specific heat capacity of the refrigerant, in units of... m refers to the refrigerant mass flow rate, measured in kg / min. Indicates the reflux temperature. This refers to the cooling temperature, measured in °C. S2. Based on the waste heat calculated in step S1, detect the waste heat after the laser's stable operating cycle begins, and plot the waste heat change over time. Change curve; according to The change curve is selected from the heat balance line. ,make Peak of the change curve and heat balance line The enclosed area with insufficient cooling and troughs of the change curve and the heat balance line Enclosed cold storage area equal; Then there is ; in yes The average waste heat value at the trough of the change curve, in W; in yes The average waste heat value at the peak of the change curve, in W; yes The time required for the change curve to reach its first peak; yes The time required for the first peak of the change curve to end; yes The time required for the change curve to first reach a trough; yes The time required for the first trough of the change curve to end; S3, Calculate and control temperature difference ; The peak period refers to the time period when the waste heat value is within ±10% of the maximum waste heat value, and the trough period refers to the time period when the waste heat value is within ±10% of the minimum waste heat value.

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