A heat exchange capacity adjusting device and adjusting method for a separate heat pipe system

Abstract

The application discloses a heat exchange capacity adjusting device and method for a separated heat pipe system. The separated heat pipe system comprises an evaporator and a condenser. The outlet of the evaporator is connected with the inlet of the condenser through a gas phase pipe. The inlet of the evaporator is connected with the outlet of the condenser through a liquid phase pipe. An electromagnetic valve is installed on the gas phase pipe and / or the liquid phase pipe. The electromagnetic valve is electrically connected with a controller. The temperature control precision of the separated heat pipe system is adjusted by adjusting the start-stop cycle of the separated heat pipe system. The heat exchange capacity of the separated heat pipe system is adjusted by adjusting the start time proportion of the separated heat pipe system. The load temperature fluctuation and the average heat exchange rate of the separated heat pipe can be effectively controlled by adjusting the start-stop frequency and the start time proportion of the heat pipe, so that the purpose of accurately controlling the temperature of the separated heat pipe under different working conditions is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of split heat pipe, in particular to a split heat pipe system heat exchange capacity adjusting device and adjusting method. BACKGROUND

[0002] The split heat pipe is a kind of high-efficiency heat transfer technology developed on the basis of ordinary heat pipe technology. The split heat pipe is characterized in that the evaporation section and the condensation section are arranged separately, and are connected by a pipeline to form a closed loop. The split heat pipe not only has the characteristics of repeated phase change heat transfer and two-phase flow circulation of the traditional heat pipe, but also has the most remarkable feature that the condensation section and the evaporation section are arranged separately, and the steam and the condensate flow in the same direction. The circulation of the working medium in the split heat pipe is caused by gravity and temperature difference, and the working state is not controlled by human beings. The heat exchange efficiency is relatively stable during normal operation. At the same time, it also shows that the traditional split heat pipe has weak temperature control ability and cannot meet the demand of precise temperature control.

[0003] In some application scenarios with high requirements for temperature control accuracy, such as medical refrigerators, which are mainly used for long-term cold storage of medicines, reagents, vaccines, etc., larger temperature fluctuations will affect the effectiveness of stored reagents. In a precision machining workshop, thermal deformation is one of the factors affecting machining precision. The temperature rise of each part of the machine tool is not uniform due to the influence of changes in the workshop environment temperature, heating of the motor and mechanical movement friction, which will cause changes in the shape precision of the machine tool and the machining precision. Therefore, improving the temperature accuracy is beneficial to improving the machining precision.

[0004] In the existing scheme, the temperature sensor is used to control the start and stop of the split heat pipe to realize load temperature control, which can meet the demand of high-precision temperature control to a certain extent. However, the temperature control accuracy is limited by the measurement error of the temperature sensor. For example, the sensitivity of a general thermocouple is about 1 DEG C, and the sensitivity of a platinum resistance temperature sensor is about 0.2 DEG C. Moreover, the temperature measurement of the local position of the load cannot accurately represent the temperature of each part, resulting in a temperature fluctuation of the final load often exceeding 0.5 DEG C, which cannot meet the special application scenarios with high temperature control accuracy requirements such as precision instruments. Higher-precision temperature controllers will significantly increase the initial investment, and their high economic cost is not conducive to the large-scale application of the technology. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a split heat pipe system heat exchange capacity adjusting device and adjusting method to effectively control the load temperature fluctuation and average heat exchange rate of the split heat pipe.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is: a heat exchange amount adjusting method for a separate heat pipe system, the separate heat pipe system comprising an evaporator and a condenser; the outlet of the evaporator is connected with the inlet of the condenser through a gas phase pipe; the inlet of the evaporator is connected with the outlet of the condenser through a liquid phase pipe; an electromagnetic valve is installed on the gas phase pipe and / or the liquid phase pipe; the electromagnetic valve is electrically connected with a controller; the method comprises:

[0007] By adjusting the start-stop cycle t of the separate heat pipe system, the temperature control precision of the separate heat pipe system is adjusted; and / or

[0008] By adjusting the start time proportion of the separate heat pipe system, the heat exchange amount of the separate heat pipe system is adjusted.

[0009] Wherein, the start-stop cycle t is set as t=t1+t2, t1 and t2 are the start time and the closing time of the electromagnetic valve respectively.

[0010] The present application adjusts the temperature control precision of the separate heat pipe by adjusting the start-stop frequency and the start time proportion of the separate heat pipe, adjusts the temperature control precision of the separate heat pipe by the influence of different start-stop frequencies on the running temperature variation range of the evaporator of the separate heat pipe, changes the start time proportion, lengthens or shortens the heat exchange time of the heat pipe, and thereby increases or decreases the heat exchange amount. Therefore, the present application can effectively control the load temperature fluctuation and the average heat exchange rate of the separate heat pipe, and thereby realizes the purpose of accurately controlling the temperature of the separate heat pipe under different working conditions.

[0011] The specific implementation process of adjusting the heat exchange amount of the separate heat pipe system by adjusting the start time proportion comprises:

[0012] When the start-stop cycle is t, the temperature control precision is ΔT=k(t)t, then,

[0013] When the start-stop cycle is increased from t to mt, the temperature control precision ΔT is increased to

[0014] When the start-stop cycle is reduced from t to nt, the temperature control precision ΔT is reduced to

[0015] wherein, m, n are the multiples of the increase and decrease of the start-stop cycle respectively; k(t) is an empirical temperature control coefficient, which is related to the system structure and the start-stop cycle, and reflects the relationship between the temperature control accuracy and the start-stop cycle change, which can be determined by experimental test and calculation. The experimental determination method is as follows: first, build a separate heat pipe system, and the specific system size can be analyzed and designed according to the embodiment or the experimental environment. Adjust the controller, set the start-stop cycle t of the separate heat pipe system to 2 min, 5 min, 10 min, 15 min, 20 min, and 30 min, set the system control temperature to 22.5℃, and set the system start time ratio to 0.5; after the system runs stably, measure the data of the temperature control accuracy ΔT corresponding to the above 6 groups of start-stop cycles, and calculate and process the data to obtain the corresponding 6 groups of k(t) values. If you want to determine the empirical temperature control coefficient under different system control temperatures or start time ratios, you can measure and calculate multiple times according to the above method to form a database of k(t) values.

[0016] By adjusting the start time ratio of the separate heat pipe system, the specific implementation process of adjusting the heat exchange amount of the separate heat pipe system includes:

[0017] Under the condition that the start-stop cycle is unchanged, when the start time ratio is , the average heat exchange amount is Q, then

[0018] If the start time ratio is increased from to , the heat exchange amount is increased from Q to

[0019] If the start time ratio is reduced from to , the heat exchange amount is reduced from Q to

[0020] wherein, w, l are the multiples of the increase and decrease of the start time ratio respectively; is an empirical heat exchange correction coefficient, which is related to the system structure and the start time ratio, and reflects the relationship between the heat exchange amount and the start time ratio, which can be determined by experimental test and calculation. The experimental determination method is as follows: first, build a separate heat pipe system, and the specific system size can be analyzed and designed according to the embodiment or the experimental environment; adjust the controller, set the start-stop time ratio of the separate heat pipe system to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9, set the system control temperature to 22.5℃, and set the system start-stop cycle to 10 min; after the system runs stably, measure the data of the above 9 groups of start time ratios and system heat transfer amount Q, and calculate and process the data to obtain the corresponding 9 groups of ​The empirical heat exchange coefficient can be measured and calculated according to the above method to form a database of the value.

[0021] In the present application, the relationship between the heat exchange amount and the start-up time ratio is: Q m is the maximum theoretical heat transfer amount when the start-stop cycle is t. This relationship shows that the heat exchange amount is proportional to the start-up time ratio under the same system conditions, fully illustrating that the heat exchange amount of the heat pipe can be changed by adjusting the start-up time ratio.

[0022] The electromagnetic valve is arranged at the upper end of the gas phase pipe and / or the lower end of the liquid phase pipe. The electromagnetic valve interrupts the two-phase counterflow heat exchange cycle spontaneously formed by the separate heat pipe, stops the heat transfer between the evaporator and the condenser, and fully enhances the internal gas pressure difference of the heat pipe and the accumulation of the liquid working medium in the liquid phase pipe, so as to improve the performance of the separate heat pipe in recovering the spontaneous heat exchange cycle and the heat transfer capacity after the electromagnetic valve is opened.

[0023] The present application also provides a separate heat pipe system heat exchange amount adjusting device, which comprises:

[0024] A first control unit is used to adjust the temperature control precision of the separate heat pipe system by adjusting the start-stop cycle t of the separate heat pipe system.

[0025] And / or

[0026] A second control unit is used to adjust the heat exchange amount of the separate heat pipe system by adjusting the start-up time ratio of the separate heat pipe system.

[0027] The start-stop cycle t is set as t=t1+t2, and t1 and t2 are the start-up time and the closing time of the electromagnetic valve, respectively.

[0028] The first control unit comprises:

[0029] A first adjusting module is used to increase the temperature control precision AT to when the start-stop cycle is increased from t to mt.

[0030]

[0031] A second adjusting module is used to decrease the temperature control precision AT to when the start-stop cycle is decreased from t to nt.

[0032]

[0033] Wherein, m and n are the multiples of the increase and decrease of the start-stop cycle, respectively; and k(t) is an empirical temperature control coefficient.

[0034] ​The second control unit comprises:

[0035] The first heat exchange amount adjusting module is configured to increase the heat exchange amount from Q to Q when the start-up time proportion is increased from to

[0036] The second heat exchange amount adjusting module is configured to decrease the heat exchange amount from Q to Q when the start-up time proportion is decreased from to

[0037] wherein w and l are respectively the multiple of the increase and decrease of the start-up time proportion; is an empirical heat exchange correction coefficient;

[0038]

[0039] Compared with the prior art, the present application has the beneficial effects that: the present application controls the start-stop frequency of the separated heat pipe to adjust the load temperature of the separated heat pipe, thereby reducing the fluctuation of the load temperature of the separated heat pipe. The present application controls the start-up time proportion of the separated heat pipe to adjust the average heat transfer amount of the separated heat pipe, thereby adapting to the heat transfer demand under different working conditions. The present application can make the separated heat pipe obtain the function of precise temperature control on the basis of high-frequency start-stop operation through the electromagnetic valve, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a structure schematic diagram of a separated heat pipe system;

[0041] Figure 2 is a comparison diagram of the heat pipe temperature and heat transfer amount under different start-stop frequencies;

[0042] Figure 3 is a comparison diagram of the heat pipe temperature and heat transfer amount under different start-up time proportions;

[0043] wherein: 1. evaporator 2. gas phase pipe 3. condenser 4. liquid phase pipe 5. normally closed electromagnetic valve 6. controller. DETAILED DESCRIPTION

[0044] As Figure 1 ​​​​As shown, the separated heat pipe system of the embodiment of the present application comprises an evaporator 1, a gas phase pipe 2, a condenser 3, a liquid phase pipe 4, a normally closed electromagnetic valve 5, a controller 6 and a circulating working medium. The evaporator and the condenser of the embodiment of the present application both adopt a tube fin heat exchanger, the inner diameter of the inner heat exchange tube of which is 10 mm. The gas phase pipe has an inner diameter of 10 mm and is composed of a horizontal pipe section and a vertical pipe section, the length of the horizontal pipe section being 1.3 m and the length of the vertical pipe section being 1 m. The liquid phase pipe has the same structure as the gas phase pipe. The condenser is located higher than the evaporator and is located on the right side of the evaporator. The vertical distance and the horizontal distance between the condenser and the evaporator are both 1 m. The outlet of the condenser is connected to the upper end of the vertical pipe section of the liquid phase pipe, and the inlet is connected to the right end of the horizontal pipe section of the gas phase pipe. The outlet of the evaporator is connected to the upper end of the vertical pipe section of the gas phase pipe, and the inlet is connected to the left end of the horizontal pipe section of the liquid phase pipe. The normally closed electromagnetic valve is installed on the liquid phase pipe. The electromagnetic valve has good sealing performance for fluid in the closed state, and has small local resistance in the powered state. The controller is connected to the normally closed electromagnetic valve. The materials of all the pipe sections are purple copper, and the circulating working medium is R134a.

[0045] During the operation of the separated heat pipe system of the embodiment of the present application, the controller sets a time parameter of the opening and closing of the electromagnetic valve in a start-stop cycle to control the heat transferred by the system, so as to achieve the purpose of accurate temperature control.

[0046] Under the heat exchange working condition, the controller 6 sets the start time t1 and the stop time t2 of the electromagnetic valve, and the start-stop cycle t=t1+t2. In the t1 time period, the controller 6 controls the electromagnetic valve 5 to be in the open state, and the separated heat pipe normally exchanges heat. In the t2 time period, the controller 6 controls the circuit to be open, and the electromagnetic valve 5 is changed to the closed state. No liquid working medium flows through the evaporator 1, the liquid working medium passing through the condenser 3 is gathered in the liquid phase pipe 4, the heat exchange capacity of the evaporator 1 is reduced, and the temperature gradually rises. The temperature difference between the evaporator 1 and the condenser 3 gradually increases. After the time t, the separated heat pipe completes a cycle of start-stop heat exchange, and then under the action of the controller 6, the heat pipe will perform the next cycle of start-stop heat exchange. The start time and the stop time of the electromagnetic valve 5 are t1 and t2.

[0047] In this embodiment of the invention, the relationship between the system temperature control accuracy and the start-stop cycle is: ΔT = k(t)t. Where k(t) is the empirical temperature control coefficient, and the relationship between k(t) and t is approximately linear. The actual relationship can be obtained through experimental measurement based on actual operating conditions. The method for determining the empirical temperature control coefficient is as follows: Based on the split heat pipe system described in this embodiment, adjust the controller and set the start-stop cycle t of the split heat pipe system to 2 min, 5 min, 10 min, 15 min, 20 min, and 30 min. Set the system control temperature to 22.5℃ and the system start-up time percentage to 0.5. After the system stabilizes, measure the temperature control accuracy ΔT data corresponding to the above 6 sets of start-stop cycles, and perform calculation processing on the data to obtain the corresponding 6 sets of k(t) values. To determine the empirical temperature control coefficient under different system control temperatures or start-up time percentages, multiple measurements and calculations can be performed using the above method to form a database of k(t) values ​​(such as a list or line graph).

[0048] In this embodiment of the invention, the temperature control accuracy adjustment rule is as follows: if the start-stop cycle is t = 10 min and the temperature control accuracy is ΔT = k(t)t, then if the start-stop cycle is increased from t to 1.5t = 15 min, the temperature control accuracy will correspondingly increase from ΔT to k(t)t. If the start-stop cycle is reduced from t to 0.5t = 5 minutes, the temperature control accuracy will correspondingly decrease from ΔT to... Adjusting the start-stop cycle t of the system regulates both the start-up and stop times of the split heat pipe. In applications requiring high temperature control accuracy, such as vaccine transportation and storage, and chip and precision instrument manufacturing workshops, where the temperature control accuracy needs to be improved from 1℃ to 0.1℃~0.2℃, the start-stop cycle t should be appropriately reduced. This will bring the actual temperature closer to the set temperature, significantly reducing the temperature fluctuation range of the split heat pipe load and improving its precise temperature control performance.

[0049] In this embodiment of the invention, the relationship between heat exchange and start-up time is as follows: Where Q represents the actual heat exchange, As a percentage of startup time, This is an empirical heat exchange correction factor, determined experimentally from actual operating conditions, and... Nearly linear correlation, Q m The maximum theoretical heat exchange is given by the start-stop cycle t. The empirical heat exchange correction factor is determined as follows: Based on the split heat pipe system described in this embodiment, the start-up time percentage of the split heat pipe system is set. The values ​​are 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9. The system control temperature is set to 22.5℃, and the system start-stop cycle is 10 minutes. After the system stabilizes, the heat exchange rate Q is measured for each of the above nine start-up time percentages. The data is then processed to obtain the corresponding nine sets of... If the empirical temperature control coefficient under different system control temperature or start-up time proportion is to be determined, the above method can be used for multiple times of measurement and calculation to form a database (such as a list or a line graph) of the values.

[0050] In the embodiment of the present application, the heat exchange amount adjustment rule is: under the condition that the temperature control precision is unchanged, i.e. the start-stop cycle is unchanged, if the start-up time proportion is , the average heat exchange amount is Q; if the start-up time proportion is increased from to , the actual heat exchange amount is increased from Q to ; if the start-up time proportion is decreased from to , the actual heat exchange amount is decreased from Q to .When the system is in a working environment with large heat exchange demand, such as a temperature control environment of a large data center, when the load of the temperature control environment changes, the start-stop cycle can be controlled to be unchanged under the premise that the temperature control precision is unchanged, and the start-up time proportion of the heat pipe can be appropriately increased to increase the average heat exchange rate; the average heat exchange rate is actively changed to achieve accurate regulation of the load temperature.

[0051] For example, in one start-stop cycle, the electromagnetic valve is started for 5 minutes and stopped for 5 minutes, and the start-up time proportion is 0.5. At the initial moment, the system is started, and the controller controls the electromagnetic valve to be opened. The circulating working medium is evaporated into gas in the evaporator, enters the condenser through the gas phase pipe, releases heat to become liquid, and returns to the evaporator through the liquid phase pipe. The heat transfer amount in the whole process is 500 J, and the load temperature is reduced from 23°C to 22°C. At the 5th minute, the electromagnetic valve returns to the closed state, the circulation stops, and the liquid working medium accumulated in the pipe segment above the electromagnetic valve stops heat transfer, and the load temperature rises from 22°C to 23°C. At the 10th minute, the controller controls the electromagnetic valve to be opened again, and the liquid working medium continues to return to the evaporator to form a cycle again.

[0052] Further, in order to adjust the temperature control precision, the start-stop frequency of the electromagnetic valve can be changed. For example, in one start-stop cycle, the electromagnetic valve is started for 2 minutes and stopped for 2 minutes, and the start-stop frequency is increased. As shown in FIG. 6, under the high start-stop frequency, the load temperature fluctuation range of the system is reduced to 22.4°C-22.6°C, and it can be seen that the temperature control precision of the separate heat pipe is improved under the high-frequency start-stop operation mode. Figure 2

[0053] Further, in order to control the average heat transfer amount Q of the separate heat pipe, the start-up time proportion of the electromagnetic valve can be changed. In the same start-stop cycle, the electromagnetic valve is started for 8 minutes and stopped for 2 minutes. The start-up time proportion is increased to 0.8, as shown in FIG. 7.​​Figure 3 As shown, the average heat transfer of the separated heat pipe in the start-stop cycle is increased to 800 J.

Claims

1. A method for regulating heat exchange capacity of a separate heat pipe system, the separate heat pipe system comprising an evaporator and a condenser; an outlet of the evaporator being connected with an inlet of the condenser through a gas phase pipe; an inlet of the evaporator being connected with an outlet of the condenser through a liquid phase pipe; an electromagnetic valve being installed on the gas phase pipe and / or the liquid phase pipe. The electromagnetic valve is electrically connected with the controller; characterized in that, The method comprises: By adjusting the starting time proportion of the separate heat pipe system, the heat exchange amount of the separate heat pipe system is adjusted; Wherein, start-stop cycle Set to , , Respectively, the electromagnetic valve start time and closing time; The specific implementation process of adjusting the heat exchange amount of the separate heat pipe system by adjusting the starting time proportion of the separate heat pipe system comprises: In the case of unchanged start-stop cycle, the ratio of start time is set as The heat exchange capacity is Therefore, If the starting time proportion is increased from to , the heat exchange amount is increased from to ; If the starting time proportion is reduced from to , the heat exchange amount is reduced from to ; wherein, , are the multiple of the increase and decrease of the start-up time ratio, respectively; is the empirical heat exchange correction coefficient when the start-up time ratio is is the empirical heat exchange correction coefficient when the start-up time ratio is is the empirical heat exchange correction coefficient when the start-up time ratio is , .​​​ 2. The heat exchange amount adjusting method of a separated heat pipe system according to claim 1, wherein The relationship between the heat exchange amount and the start-up time ratio is: ; The maximum theoretical heat transfer amount of the separated heat pipe system.

3. The heat exchange amount adjusting method of a separated heat pipe system according to claim 1, wherein The electromagnetic valve is arranged at the upper end of the gas phase pipe and / or the lower end of the liquid phase pipe.

4. A heat exchange amount adjusting device for a separate heat pipe system, characterized by comprising: Comprise: The control unit is used for adjusting the heat exchange amount of the separate heat pipe system by adjusting the starting time proportion of the separate heat pipe system; Wherein, start-stop cycle Set to , , Respectively, the start time and the closing time of the electromagnetic valve; The control unit comprises: The first heat exchange amount adjusting module is configured to increase the heat exchange amount from to when the start time proportion is increased from to . The second heat exchange amount adjusting module is configured to reduce the heat exchange amount from to when the start time proportion is less than to . wherein, , are the multiples of the increase and decrease of the start-up time ratio, respectively; is the empirical heat exchange correction coefficient when the start-up time ratio is , is the empirical heat exchange correction coefficient when the start-up time ratio is , is the empirical heat exchange correction coefficient when the start-up time ratio is , , .

5. The separated heat pipe system heat exchange amount adjusting device according to claim 4, characterized by, The relationship between average heat exchange and the ratio of start-up time is: ; The maximum theoretical heat transfer of the separated heat pipe system.

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