A cooling capacity control method for a chiller based on average waste heat of laser

Abstract

The present invention belongs to the technical field of laser chiller control methods, and in particular, relates to a chiller cooling capacity control method based on the average waste heat of the laser. The method comprises the following steps: detecting the waste heat generated by the laser during operation according to the flow temperature difference method and drawing a curve of the change of waste heat over time; drawing a cooling capacity balance line, and using the cooling capacity corresponding to the cooling capacity balance line as the cooling power of the chiller to control the output of the chiller. The present application adopts a more reasonable control of the chiller cooling capacity output power, suppresses or avoids the phenomenon of the cooling process, improves the utilization of cooling power, and reduces resource waste; it is conducive to reducing the output pressure of the chiller, reducing the start and stop frequency of the compressor, and increasing the effective life of the compressor and the refrigeration system; it can simplify the chiller cooling output control method and improve the control effectiveness and scientificity.

Description

Technical Field

[0001] The invention belongs to the technical field of laser chiller control methods, and in particular relates to a chiller cooling capacity control method based on average waste heat of a laser. Background Art

[0002] The function of the laser chiller is to cool the laser. The laser will generate a lot of waste heat during welding, cutting, cleaning and other operations. This part of waste heat is taken away by the chiller to ensure that the laser can continue to work. The waste heat generated by most lasers during operation is fluctuating, with periodic changes in peaks and troughs. In order to ensure the safety and stability of the laser, the cooling output power of the chiller currently equipped in the laser manufacturing industry is generally based on the waste heat output of the laser's peak value (maximum value) as the cooling output standard of the chiller. Although this can ensure that the laser is effectively cooled throughout the entire working cycle, during the trough period, the waste heat generated by the laser drops significantly and is far lower than the high cooling output power of the chiller, resulting in excess cooling capacity, which is what the industry calls "a big horse pulling a small cart". On the one hand, this leads to unnecessary waste of cooling resources, and on the other hand, it leads to a larger designed cooling capacity than actually required, which not only requires a higher-power cooling system, but also increases the output pressure of the compressor and increases its start-stop frequency, which increases costs and affects the effective life of the compressor and even the entire cooling system. Summary of the invention

[0003] The purpose of the present invention is to actively control the cooling power of the chiller by actively analyzing and establishing the waste heat output during the operation of the laser, so that the output control of the chiller is more efficient and scientific, so as to improve the utilization of cooling power and reduce the output pressure of the refrigeration system.

[0004] To achieve the above purpose, the present invention adopts the following technical solution.

[0005] A method for controlling the cooling capacity of a chiller based on average waste heat of a laser comprises the following steps:

[0006] 1) The waste heat Q generated by the laser during operation is detected according to the flow temperature difference method, which is 0.07·m·(T1-T2); where: Q represents the waste heat, in kW; m represents the water flow, in L / min; T1 represents the return water temperature, in °C; T2 represents the outlet water temperature, in °C;

[0007] 2) According to the detected waste heat data, a coordinate system is established with the detection time t as the horizontal axis and the waste heat value Q as the vertical axis, and a curve Q(t) of the change of the waste heat value Q over time t is plotted;

[0008] 3) Draw the cooling capacity balance line Q parallel to the horizontal axis ave , adjust the cooling capacity balance line Q up and downave The position of the cooling capacity is such that within the required cooling cycle Δt, the curve Q(t) is located on the cooling capacity balance line Q ave The upper line segment and the cooling capacity balance line Q ave The enclosed area S a =a1+a2....a i The curve Q(t) is located on the cooling capacity balance line Q ave The line segment on the lower side and the cooling capacity balance line Q ave The enclosed area S b =b1+b2....b j Equal, expressed as:

[0009]

[0010] where a i It means that within the cooling cycle Δt=t1~t2, the i-th segment on the curve Q(t) is located on the cooling capacity balance line Q ave The upper line segment and the cooling capacity balance line Q ave The area enclosed; b j It means that within the cooling cycle Δt, the jth segment on the curve Q(t) is located on the cooling capacity balance line Q ave The line segment on the lower side and the cooling capacity balance line Q ave The area enclosed; refrigeration cycle Δt = t′~t″, t′ refers to the start time of the refrigeration cycle, and t″ refers to the end time of the refrigeration cycle;

[0011] 4) Cooling capacity balance line Q ave The corresponding cooling capacity is used as the cooling power of the chiller to control the output of the chiller.

[0012] Further improvement and supplement to the above-mentioned chiller cooling capacity control method based on the average waste heat of the laser, for a laser with a stable heat load, after the laser works stably, a curve Q(t) of the waste heat Q versus time t is drawn based on the above-mentioned steps 1) to 2); and the cooling capacity balance line Q is calculated based on the following formula ave Adjust the cooling power of the chiller:

[0013]

[0014] Where Q1 and Q2 refer to the average waste heat values ​​of the curve Q(t) at the trough and peak stages respectively, t2-t1 is the peak duration, and t3 refers to the interval time between the two troughs of the curve Q(t).

[0015] Its beneficial effects are:

[0016] 1. More reasonably control the cooling output power of the chiller, suppress or avoid the phenomenon of the refrigeration process, improve the utilization of refrigeration power, and reduce resource waste;

[0017] 2. Reduce the output pressure of the chiller, reduce the start and stop frequency of the compressor, and increase the effective life of the compressor and refrigeration system;

[0018] 3. Simplify the cooling output control method of the chiller to improve the effectiveness and scientificity of the control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of modeling the cooling capacity control of the chiller based on the average waste heat of the laser;

[0020] Figure 2 This is the waste heat curve test diagram of the laser;

[0021] Figure 3 It is a modeling schematic diagram of the cooling capacity control of a water chiller for a laser with a stable thermal load. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with specific embodiments.

[0023] As the output power of the laser continues to increase, the requirements for the cooling power of the supporting refrigeration system (generally a chiller) are also getting higher and higher. The design standard of the cooling power of the traditional chiller cooling solution is generally the maximum waste heat of the laser, which leads to the continuous increase in the power and volume of the chiller system. At the same time, the compressor in the refrigeration system needs frequent start and stop control to ensure stable power output. The original purpose of the chiller's excess cooling capacity configuration was to more effectively ensure the cooling effect of the chiller and ensure the stable operation of the laser. However, with the further increase in power and volume, the cost of the refrigeration system itself has increased rapidly. Due to the excessive refrigeration power in the system, the difficulty of controlling stable output has continued to increase, and the phenomenon of excess refrigeration has become more serious. The output pressure and control difficulty of the compressor and the self-circulation system in the refrigeration system have continued to increase, which in turn leads to a decrease in the stability and service life of the refrigeration system itself, which in turn directly affects the stability of the laser, and becomes too much.

[0024] In response to this phenomenon, the present application considers combining the waste heat output characteristics during the operation of the laser and reasonably controlling the cooling output power of the chiller based on drawing the thermal curve data, in order to suppress or avoid the cooling process phenomenon, thereby achieving energy conservation and emission reduction, reducing the output pressure and control difficulty of the refrigeration system, and improving its stability and service life.

[0025] This application first needs to determine the waste heat output data of the laser (heat load) and perform cooling capacity control based on the corresponding data. To simplify the process and facilitate the design of the control scheme, the specific steps in this application are as follows:

[0026] 1) The waste heat Q generated by the laser during operation is detected according to the flow temperature difference method, which is 0.07·m·(T1-T2); where: Q represents the waste heat, in kW; m represents the water flow, in L / min; T1 represents the return water temperature, in °C; T2 represents the outlet water temperature, in °C;

[0027] 2) According to the detected waste heat data, a coordinate system is established with the detection time t as the horizontal axis and the waste heat value Q as the vertical axis, and a curve Q(t) of the change of the waste heat value Q over time t is plotted;

[0028] 3) Draw the cooling capacity balance line Q parallel to the horizontal axis ave , adjust the cooling capacity balance line Q up and down ave The position of the cooling capacity is such that within the required cooling cycle Δt, the curve Q(t) is located on the cooling capacity balance line Q ave The upper line segment and the cooling capacity balance line Q ave The enclosed area S a =a1+a2....a i The curve Q(t) is located on the cooling capacity balance line Q ave The line segment on the lower side and the cooling capacity balance line Q ave The enclosed area S b =b1+b2....b j Equal, expressed as:

[0029]

[0030] where a i It means that within the cooling cycle Δt=t1~t2, the i-th segment on the curve Q(t) is located on the cooling capacity balance line Q ave The upper line segment and the cooling capacity balance line Q ave The enclosed area; b j It means that within the cooling cycle Δt, the jth segment on the curve Q(t) is located on the cooling capacity balance line Q ave The line segment on the lower side and the cooling capacity balance line Q ave The area enclosed; refrigeration cycle Δt = t′~t″, t′ refers to the start time of the refrigeration cycle, and t″ refers to the end time of the refrigeration cycle;

[0031] 4) Cooling capacity balance line Q ave The corresponding cooling capacity is used as the cooling power of the chiller to control the output of the chiller.

[0032] The above control process and principle can be used Figure 1 The control model in Figure 2The waste heat curve test diagram of the laser shown and the design cooling capacity control curve drawn in the figure illustrate that the main purpose of this scheme is to change the traditional interference design method and utilize the refrigeration cycle system to achieve the supercooling cooling capacity (waste heat curve trough stage) generated in the waste heat low output stage to make up for the insufficient cooling (waste heat curve peak stage) generated in the waste heat high output stage. The circulating flow of cooling water in the chiller provides the basis for realizing the transfer of cooling capacity in different stages. During the implementation process, the continuous improvement of the control efficiency of the cooling cycle system and the improvement of the energy storage capacity of the cooling medium provide the basic foundation for realizing pre-cooling, cooling capacity storage and cooling capacity recycling, which is also the background that can be realized in this application.

[0033] In the actual implementation process, the area enclosed by the above waste heat curve and the cooling power curve directly corresponds to the cold exchange and cooling process during the operation of the system. It should be noted that in actual applications, the waste heat curve is not actually a smooth trigonometric function curve. It is still in a fluctuating state within a smaller time dimension, but the overall curve shows the peaks and troughs associated with the periodic start-up of the laser. The better the control effect and the more stable the output of the laser, the more stable its waste heat curve. In specific implementation, it should be understood that the peaks and troughs described in this application should refer to the phased changes related to the periodic output of the laser shown in the overall trend of the waste heat curve rather than the small time dimension. The fluctuations generated in the cooling system, wherein the cooling output power does not remain stable, but fluctuates with the periodic operation of the compressor. However, in this application, based on the refrigeration and cooling capacity hysteresis cycle method, the cooling capacity in the supercooling stage is used to make up for the lack of cooling capacity in the insufficient cooling stage, thereby achieving the overall balance of cooling capacity. The cooling power curve described in this application is an expression of the average cooling output of the chiller. In the actual implementation process, it also has fluctuating changes related to the start and stop state of the compressor. As a technician in the relevant field, it can be understood that in order to ensure the cold and heat balance in the whole process and improve the stability of the system, the cooling output of the refrigeration system should be kept as close as possible to the cooling power curve.

[0034] Considering that the output power control method of the new laser is more stable, for lasers with stable heat load, the output curve is smoother and more consistent. Most of them have very clear periodic waveforms, and generally appear as a trigonometric function with stable peak segments (high waste heat output segments) and trough segments (low or no waste heat output segments). Therefore, after the laser is working stably, based on the above steps 1) to 2), the curve Q(t) of the waste heat Q versus time t is plotted, and the result can be obtained. Figure 3 The change curve shown in the figure can be used to quickly and easily calculate and adjust the cooling power of the chiller. The cooling capacity balance line Q is calculated based on the following formula: ave :

[0035]

[0036] Where Q1 and Q2 refer to the average waste heat values ​​of the curve Q(t) at the trough and peak stages respectively, t2-t1 is the peak duration, and t3 refers to the interval time between the two troughs of the curve Q(t).

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A chiller cooling capacity control method based on average waste heat of laser, characterized in that: The steps include: 1) The waste heat Q generated by the laser during operation is detected according to the flow temperature difference method, which is 0.07·m·(T1-T2); where: Q represents the waste heat, in kW; m represents the water flow, in L / min; T1 represents the return water temperature, in °C; T2 represents the outlet water temperature, in °C; 2) According to the detected waste heat data, a coordinate system is established with the detection time t as the horizontal axis and the waste heat value Q as the vertical axis, and a curve Q(t) of the change of the waste heat value Q over time t is plotted; 3) Draw the cooling capacity balance line Q parallel to the horizontal axis ave , adjust the cooling capacity balance line Q up and down ave The position of the cooling capacity is such that within the required cooling cycle Δt, the curve Q(t) is located on the cooling capacity balance line Q ave The upper line segment and the cooling capacity balance line Q ave The enclosed area S a =a1+a2....a i The curve Q(t) is located on the cooling capacity balance line Q ave The line segment on the lower side and the cooling capacity balance line Q ave The enclosed area S b =b1+b2....b j Equal, expressed as: where a i It means that within the cooling cycle Δt=t1~t2, the i-th segment on the curve Q(t) is located on the cooling capacity balance line Q ave The upper line segment and the cooling capacity balance line Q ave The enclosed area; b j It means that within the cooling cycle Δt, the jth segment on the curve Q(t) is located on the cooling capacity balance line Q ave The line segment on the lower side and the cooling capacity balance line Q ave The area enclosed; refrigeration cycle Δt = t′~t″, t′ refers to the start time of the refrigeration cycle, and t″ refers to the end time of the refrigeration cycle; 4) Cooling capacity balance line Q ave The corresponding cooling capacity is used as the cooling power of the chiller to control the output of the chiller.

2. The chiller cooling capacity control method based on the average waste heat of the laser according to claim 1 is characterized in that: For a laser with a stable heat load, after the laser is working stably, a curve Q(t) of the waste heat Q versus time t is drawn based on the above steps 1) to 2); and the cooling balance line Q is calculated based on the following formula: ave Adjust the cooling power of the chiller: Where Q1 and Q2 refer to the average waste heat value of the curve Q(t) at the trough and peak stages respectively, t2-t1 is the peak duration, t3 refers to the interval time between the two troughs of the curve Q(t); T refers to the working cycle after the laser stabilizes.

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