Cold storage air outlet device, cold storage and refrigeration control method thereof

Abstract

The present invention relates to an air supply system of a low-temperature refrigeration dehumidifier, in particular to a cold storage air outlet device, including an air supply fan, an evaporator and a heater; it is characterized in that it also includes a heating box, the heater is installed inside the heating box, and the evaporator is installed at one end of the heating box; an air outlet box, the air outlet box is provided with an air inlet and an air outlet, and the air inlet is installed at the other end of the heating box; the air supply fan is installed at one end of the evaporator located in the heating box or on the air outlet box, and the air supply fan is used to blow the air out from the air outlet of the air outlet box after passing through the evaporator and the heater. The cold storage air outlet device provided by the present invention ensures the size of the windward area and the wind speed vector by reasonably setting the positions of the evaporator, the air supply fan, the heater and the air outlet, thereby effectively ensuring the uniform distribution of the air supply distance and air volume in the cold storage.

Description

Technical Field

[0001] The invention relates to an air supply system of a low-temperature refrigeration dehumidifier, in particular to a cold storage air outlet device, a cold storage and a refrigeration control method thereof. Background Art

[0002] There are many types of cold storage, among which low-temperature cold storage used to store seeds has higher requirements for temperature and humidity. Long-term seed cold storage is used to store seeds for a long time. The temperature in the storage is controlled in the range of -10℃~-20℃, and the relative humidity is not more than 60%. The international reference standard recommended for long-term storage of normal seeds is a temperature condition of -18℃ or lower. Some seed banks also have higher requirements for temperature uniformity.

[0003] Refrigeration dehumidification is a commonly used dehumidification method. However, when the cold storage has very high uniformity and precision requirements for the temperature and humidity in the storage, how to ensure the uniformity and precision requirements of the temperature and humidity in the storage while dehumidifying is quite difficult for equipment manufacturers. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a cold storage air outlet device which can effectively ensure the uniformity and accuracy of temperature and humidity and has a simple structure. The specific technical solution is as follows:

[0005] The cold storage air outlet device includes an air supply fan, an evaporator and a heater; it also includes a heating box, the heater is installed inside the heating box, and the evaporator is installed at one end of the heating box; an air outlet box, the air outlet box is provided with an air inlet and an air outlet, and the air inlet is installed at the other end of the heating box; the air supply fan is installed at one end of the evaporator located in the heating box or on the air outlet box, and the air supply fan is used to blow the air out from the air outlet of the air outlet box after passing through the evaporator and the heater.

[0006] By adopting the above technical solution, the air supply fan, evaporator and heater are integrated together to make the structure simple, and the wind pressure and wind speed can be guaranteed, thereby ensuring the uniformity and precision requirements of the temperature and humidity of the cold storage. The heat of the heater does not pass through the evaporator, which can protect the evaporator and ensure that stable heat enters the cold storage, thereby avoiding drastic temperature fluctuations.

[0007] Furthermore, the axis of the air outlet is parallel to, perpendicular to, or intersects with the axis of the air flow direction of the evaporator.

[0008] Furthermore, an evaporation casing, wherein the evaporator is installed in the evaporation casing; and a defrost water receiving tray, wherein the defrost water receiving tray is arranged at the bottom of the evaporation casing.

[0009] By adopting the above technical solution, the defrost water receiving tray can discharge the defrosted water in a centralized manner, which is convenient to use.

[0010] Furthermore, the heater is an electric heating tube; and also includes a power regulator, which is connected to the electric heating tube.

[0011] By adopting the above technical solution, the power regulator can quickly adjust the heating power of the electric heating, thereby controlling the heating value, achieving uniform temperature control, and avoiding large fluctuations in the temperature inside the cold storage.

[0012] Furthermore, the air supply fan is a speed-regulating fan.

[0013] By adopting the above technical solution, the speed-adjustable fan is used to adjust the air volume, thereby controlling the uniformity and accuracy of the temperature.

[0014] A cold storage, the cold storage is a cube, including a cold storage air outlet device, the cold storage air outlet device is installed on the four corners of the top of the cold storage; a temperature sensor, at least three of the temperature sensors are installed on the diagonal of the cold storage and are evenly arranged, and the temperature sensors are not on the air outlet and the corners; a humidity sensor, at least three of the humidity sensors are arranged along the length direction of the cold storage, and the humidity sensors are respectively located in the middle and bottom of the height direction of the cold storage, and the humidity sensors are not at the air outlet and the corners of the cold storage; a defrost temperature sensor, the defrost temperature sensor is installed on the evaporator; an intake pressure sensor; a variable frequency compressor, the evaporator is connected to the variable frequency compressor, and the intake pressure sensor is installed on the pipeline between the evaporator and the variable frequency compressor; a condenser, the condenser is connected to the variable frequency compressor; an electronic expansion valve, the electronic expansion valve is connected to the condenser and the evaporator respectively; a PLC controller, the temperature sensor, the humidity sensor, the defrost temperature sensor, the intake pressure sensor, the variable frequency compressor, the electronic expansion valve, the air supply fan and the heater are all connected to the PLC controller.

[0015] By adopting the above technical solution, the temperature and humidity in different areas are checked to ensure the uniformity and accuracy of temperature and humidity.

[0016] The variable frequency compressor and electronic expansion valve are easy to control and can respond instantly, ensuring the stability and uniformity of temperature and achieving energy saving. The cold storage air outlet devices are installed at the four corners to achieve uniform temperature inside the cold storage.

[0017] Furthermore, the length of the cold storage is 40-50 meters, the width is 4-7 meters, and the height is 10-13 meters; the distance between the air outlet of the cold storage air outlet device and the side wall of the cold storage end is 1-1.4 meters, and the distance between the air outlet and the side wall of the cold storage side is 1-1.3 meters.

[0018] A cold storage refrigeration control method, including a temperature control method, wherein the temperature control method includes calculating the current average temperature of the cold storage according to the temperatures measured by a plurality of temperature sensors, and if the current average temperature of the cold storage is greater than the set temperature, the refrigeration mode is entered, in which the air supply fan rotates at the highest speed, and the opening of the electronic expansion valve is controlled according to the suction superheat, and the output frequency of the compressor is adjusted; if the current average temperature of the cold storage is less than the set temperature, the refrigeration is turned off; a humidity control method, wherein the humidity control method includes calculating the current average humidity of the cold storage according to the humidity measured by a plurality of humidity sensors, and if the current average humidity of the cold storage is greater than the set humidity, the dehumidification mode is entered, in which the storage temperature set value and the evaporation temperature of the refrigeration unit are reduced to the set temperature in the dehumidification mode, and the set temperature in the dehumidification mode is a temperature obtained by automatically reducing the temperature by a controller according to the current storage temperature and the storage temperature set value floating setting, based on the The opening of the electronic expansion valve is controlled according to the current temperature of the cold storage and the rate of decrease of the temperature of the cold storage, the output frequency of the compressor is adjusted according to the suction pressure and the rate of decrease of the suction pressure, the speed of the supply fan is controlled according to the current temperature of the cold storage and the current output frequency of the compressor, and during the dehumidification process, if the current temperature of the cold storage is lower than the set protection temperature, the heater is started and the heater is controlled by the PID method; if the current average humidity of the cold storage is lower than the set humidity, the dehumidification is turned off; the defrost control method includes defrost judgment, if the cumulative refrigeration operation time of the unit reaches the set cycle and the temperature of the fin is lower than the set defrost temperature, the defrost mode is entered, and the defrost is terminated when the fin temperature is higher than the defrost termination temperature or the defrost time is greater than the set maximum defrost time; wherein, the priority level of the defrost mode is greater than the priority level of refrigeration, and the priority level of refrigeration is greater than the priority level of initial dehumidification.

[0019] Furthermore, in the cooling mode, the frequency adjustment float of the compressor is calculated according to the deviation interval between the suction pressure and the corresponding evaporation pressure at the set evaporation temperature, and the output speed of the compressor is adjusted according to the set frequency adjustment interval;

[0020] The amplitude of the compressor frequency adjustment is:

[0021] f=f1*(P-P0) / (P1-P0),

[0022] P0 = 0.5 * (P1 + P2);

[0023] f1 is the frequency modulation coefficient;

[0024] P is the measured value of the suction pressure;

[0025] P1 is the saturated gas pressure corresponding to the set refrigeration temperature T1;

[0026] P2 is the saturated gas pressure corresponding to the set refrigeration temperature T2.

[0027] Furthermore, it also includes compressor frequency modulation amplitude correction, which is used to recalculate the compressor frequency adjustment amplitude: t=a*t1, where a is the correction value of the sampling adjustment period, calculated according to the decrease rate of the suction pressure, and used to change the time interval of the adjustment frequency; t1 is the set frequency modulation interval.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The cold storage air outlet device provided by the present invention ensures the size of the windward area and the wind speed vector by reasonably arranging the positions of the evaporator, the air supply fan, the heater and the air outlet, thereby effectively ensuring the uniform distribution of the air supply distance and the air volume in the cold storage.

[0030] The cold storage provided by the present invention has reasonable structural design, high temperature and humidity control progress and good uniformity.

[0031] This method optimizes the design of evaporator air supply and reasonably distributes the temperature and humidity sensor measurement points to ensure the rationality of the temperature and humidity points in the warehouse.

[0032] Select frequency converters, power regulators, electronic expansion valves, adjustable speed air supply motors and other components to achieve intelligent control, accurately adjust the temperature and humidity of the cold storage, reduce fluctuations in temperature and humidity in the storage, and improve energy-saving effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the distribution of the surface wind speed of the evaporator at different air outlets when the wind pressure is 0Pa;

[0034] Figure 2 It is the distribution of the surface wind speed of the evaporator at different air outlets when the wind pressure is 105Pa;

[0035] Figure 3 is the distribution of wind speed vectors at different outlets;

[0036] Figure 4 This is an exploded view of the cold storage air outlet device;

[0037] Figure 5 This is the front view of the cold storage air outlet device;

[0038] Figure 6 It is the maximum relative humidity on the surface and inside of the cold storage;

[0039] Figure 7 It is the maximum temperature and maximum temperature difference of the cold storage surface under different installation distances of the cold storage air outlet device;

[0040] Figure 8It is the maximum temperature and maximum temperature difference inside the cold storage at different installation distances of the cold storage air outlet device;

[0041] Fig. 9 This is a schematic diagram of the installation of the cold air outlet device in the cold storage;

[0042] Fig.10 It is a flow chart of the cold storage control method. DETAILED DESCRIPTION

[0043] The present invention will be further described with reference to the accompanying drawings.

[0044] Embodiment 1

[0045] like Figures 1 to 5 As shown, the cold storage air outlet device includes an air supply fan 2, an evaporator 1 and a heater 6; it also includes a heating box 5, the heater 6 is installed inside the heating box 5, and the evaporator 1 is installed at one end of the heating box 5; an air outlet box 7, the air outlet box 7 is provided with an air inlet and an air outlet, and the air inlet is installed at the other end of the heating box 5; the air supply fan 2 is installed on the evaporator 1 at one end of the heating box 5 or on the air outlet box 7, and the air supply fan 2 is used to blow the air out from the air outlet of the air outlet box 7 after passing through the evaporator 1 and the heater 6.

[0046] The axis of the air outlet is parallel, perpendicular or intersecting with the axis of the airflow direction of the evaporator 1. That is, the evaporator 1 is vertically arranged, the air outlet surface of the evaporator 1 is vertically arranged, and the air outlet is vertically arranged, inclined or parallel to the air outlet surface of the evaporator 1.

[0047] The evaporator 1 is installed in the evaporator shell 3 , and the defrost water receiving tray 4 is arranged at the bottom of the evaporator shell 3 .

[0048] The heater 6 is an electric heating tube. A power regulator is also included, which is connected to the heater 6. The power regulator can realize stepless regulation of heating output power.

[0049] The air supply fan 2 is a speed-adjustable fan. The speed-adjustable fan may be an EC fan or a variable frequency fan. The air supply fan 2 is an axial flow fan.

[0050] Specifically, three forms can be set, and the air supply fan 2 is located at the air outlet for illustration.

[0051] Solution 1: The air outlet is arranged in parallel with the evaporator 1.

[0052] Solution 2: The air outlet and the evaporator 1 are arranged at an angle.

[0053] Solution three, the air outlet is arranged vertically to the evaporator 1.

[0054] Table 1 shows the wind speed on the surface of evaporator 1 when different solutions are adopted for the air outlet:

[0055]

[0056] like Figures 1 to 3 As shown in the analysis, in the cooling mode, different air outlet designs have little effect on the air supply speed of the air supply fan 2, but have an impact on the size of the windward surface and the distribution of the wind speed vector. Considering that when the air supply fan 2 works in the dehumidification mode, in order to ensure the stability of the warehouse temperature, when the warehouse temperature is lower than the set value, it is necessary to heat the electric heater 6 to maintain the constant warehouse temperature. When the electric heater 6 is heating, the size of the windward surface and the wind speed vector have a relatively large impact on the heating effect. At the same time, in order to ensure the uniform distribution of the air supply distance and air volume in the cold storage, the third scheme is the best air outlet scheme.

[0057] like Figure 4 and Figure 5 As shown, the evaporator 1 and the air supply fan 2 adopt the existing integrated machine, the air supply fan 2 is installed in the heating box 5, the air outlet is perpendicular to the air outlet surface of the evaporator 1, and the air enters from the evaporator 1 and blows out from the air outlet. The integrated machine is convenient to use, and the air supply fan 2 is located close to the position of the scheme three, and the effect is basically the same.

[0058] Embodiment 2

[0059] Cold storage, the cold storage is a cube, including a cold storage air outlet device, which is installed on the four corners of the top of the cold storage; temperature sensor, there are no less than three temperature sensors, which are installed on the diagonal of the cold storage and are evenly arranged, and the temperature sensors are not on the air outlet and corners; humidity sensor, there are no less than three humidity sensors, which are arranged along the length direction of the cold storage, and the humidity sensors are respectively located in the middle and bottom of the height direction of the cold storage, and the humidity sensors are not at the air outlet and the corners of the cold storage; defrost temperature sensor, the defrost temperature sensor is installed on the evaporator; suction pressure sensor; variable frequency compressor, the evaporator is connected to the variable frequency compressor, and the suction pressure sensor is installed on the pipeline between the evaporator and the variable frequency compressor; condenser, the condenser is connected to the variable frequency compressor; electronic expansion valve, the electronic expansion valve is connected to the condenser and the evaporator respectively; PLC controller, the temperature sensor, humidity sensor, defrost temperature sensor, suction pressure sensor, variable frequency compressor, electronic expansion valve, air supply fan and heater are all connected to the PLC controller.

[0060] The length of the cold storage is 40-50 meters, the width is 4-7 meters, and the height is 10-13 meters; the distance between the air outlet of the cold storage air outlet device and the side wall of the cold storage end is 1-1.4 meters, and the distance between the air outlet and the side wall of the cold storage side is 1-1.3 meters.

[0061] The design temperature in the cold storage is -18℃, the ambient temperature is 34℃, and the air volume of a single air supply fan is 21500m 3 ·h-1 The cold storage is surrounded by a 150mm polyurethane insulation layer with a thermal conductivity of 0.024W·m -1 ·K -1 The distance D between the air supply fan and the side wall of the cold storage will have a certain impact on the temperature and flow field distribution in the cold storage. Therefore, different schemes with D of 400 to 1400 mm are simulated. The specific schemes are as follows: Figure 4 shown.

[0062] The surface temperature distribution of the cold storage is symmetrical. Along the length direction of the cold storage, the temperature gradually increases from the left and right walls to the center. After the cold air is blown out, as it moves away from the air supply fan, the weight received in the cold storage gradually decreases, and the temperature of the cold air also rises slowly and gradually due to convection heat exchange, so that the temperature in the center area is higher than that on both sides. Along the height direction of the cold storage, the surface temperature of the upper wall is higher due to convection heat exchange with the outside world. There is a dead corner area at the installation position of the four air supply fans, and the temperature is the highest. When D changes from 400 to 1400mm, the highest temperature in the dead corner area is about -15 to -13℃ (258 to 260K). In addition, a clear jet is formed on the upper wall near the air supply fan, and the temperature changes significantly in the jet area.

[0063] Below the fan outlet, the temperature is lowest due to the strong cold wind. In the center of the cold storage, the temperature gradually rises due to the decrease in the amount of cold wind. As the fan installation distance D increases, the air volume passing through the center of the cold storage gradually increases, and the center temperature shows a downward trend. However, as it is far away from the corners of the cold storage, the maximum temperature on the surface of the cold storage will gradually increase.

[0064] The component transport model is used to calculate the humidity field distribution in the cold storage. The design temperature and humidity in the cold storage are -18℃ and RH45%, and the water vapor content in the humid air is 0.41357g / kg.

[0065] The relative humidity on the surface of the cold storage is less than 43.5%. The relative humidity is lower at the four corners where the fans are distributed due to the higher temperature. Along the length of the cold storage, the relative humidity shows a trend of "high on both sides and low in the center". Along the height of the cold storage, in the vertical direction close to the air supply fan, the relative humidity decreases with increasing height. The center area also generally shows this trend. As it is far away from the air outlet of the air supply fan, the amplitude of the change gradually decreases. The distribution of relative humidity inside the cold storage is consistent with the basic trend of the outer surface. The relative humidity does not change significantly along the width direction and is relatively evenly distributed. The relative humidity inside the storage is less than 44.5%. The maximum relative humidity on the surface and inside the cold storage is as follows: Figure 6 shown.

[0066] The maximum wind speed at the air outlet is about 19.16m / s, and the wind speed gradually decreases as the distance from the air outlet increases. In the center of the cold storage, there is almost no cold air passing through. The greater the wind speed, the stronger the turbulence of the internal flow field, which strengthens the heat transfer and makes the temperature lower. In the center of the cold storage, due to the low wind speed, the heat transfer effect is weakened, so the temperature is higher. On the walls around the cold storage, due to convection heat exchange with the external environment (temperature 34°C), the temperature is higher than the center area.

[0067] The air outlet is vertically discharged from the outlet, with the highest wind speed. After encountering the lower wall of the cold storage, the air flow gradually rises in the length direction, and the speed gradually decreases, and finally returns horizontally from the air supply fan. Since the four air supply fans in the cold storage are installed symmetrically, the flow field also shows a symmetrical trend. The fluids from both sides meet at the center and then rise.

[0068] Although the temperature is higher in the center area, the wind speed is lower within the reasonable temperature difference range, which is suitable for storing seeds or goods that are greatly affected by wind speed, and can avoid the strong airflow from affecting the plants or goods in the warehouse. Near the fan outlet, the temperature is lower, but the wind speed is higher, which is suitable for storing seeds that have stricter temperature requirements but are not affected by wind speed.

[0069] like Figure 7 As shown in the figure, with the increase of the fan installation distance D, the maximum temperature and maximum temperature difference of the cold storage surface generally show an upward trend. When D = 1400mm, the maximum temperature difference of the cold storage surface does not exceed 4.5℃, and the maximum temperature is about 260K. When D is within the range of 400-1000mm, the maximum surface temperature is basically the same, and the maximum temperature difference is about 3.5℃. Figure 8 It can be seen that the maximum temperature and maximum temperature difference inside the cold storage are basically the same as the surface change trend. When D is in the range of 400-1000mm, the maximum temperature difference inside the cold storage is less than 2°C. In practice, the fan installation position D also depends on the limitation of the manual operation space. Too small a distance is not only not conducive to manual installation and operation, but also close to the wall will form strong turbulence, which is not conducive to flow field distribution. Therefore, it is more reasonable for the air supply fan installation position D to be in the range of 400-1000mm.

[0070] The temperature change has different distributions as the distance between the measurement position and the air supply fan changes. If the temperature changes too quickly, the temperature control system will fluctuate greatly. If the temperature changes too slowly, the control system cannot guarantee the accuracy of the warehouse temperature range. In order to ensure the accuracy and stability of temperature control, the arrangement of temperature sensors should take into account the distribution of the temperature field as much as possible, and try to avoid the air outlet position where the temperature fluctuates violently, as well as the corner position of the warehouse where the temperature difference with the surrounding temperature is relatively large. Therefore, in the diagonal direction of the cold storage cube, avoid the corner and the air outlet position, and evenly select three distribution points to place sensors for the system's warehouse temperature control.

[0071] The change in humidity has different distributions as the distance between the measurement position and the air supply fan changes. Along the length direction of the cold storage, the relative humidity shows a trend of "high on both sides and low in the center". Along the height direction of the cold storage, in the vertical direction close to the air supply fan, the relative humidity decreases with increasing height, and the central area also generally shows this trend. As it is far away from the air outlet of the air supply fan, the amplitude of the change gradually decreases. The relative humidity does not change significantly along the width direction, and the distribution is relatively uniform. In order to ensure that the humidity is reliably lower than the required value and reflect the humidity in the warehouse as accurately as possible, the arrangement position of the humidity sensor can be considered along the length direction, and the installation height is distributed from the middle to the lower part, avoiding the position of the air outlet, so as to ensure that the humidity measurement value is relatively stable and reliable, and thus ensure the stable and accurate control of the humidity in the warehouse, and ensure the storage environment of the seeds.

[0072] Embodiment 3

[0073] A cold storage refrigeration control method, including a temperature control method, wherein the temperature control method includes calculating the current average temperature of the cold storage according to the temperatures measured by a plurality of temperature sensors, and if the current average temperature of the cold storage is greater than a set temperature, the cold storage enters a refrigeration mode, in which the air supply fan rotates at the highest speed, the opening of the electronic expansion valve is controlled according to the suction superheat, and the output frequency of the compressor is adjusted; if the current average temperature of the cold storage is less than the set temperature, the refrigeration is turned off;

[0074] A humidity control method, the humidity control method includes calculating the current average humidity of the cold storage according to the humidity measured by multiple humidity sensors, and entering a dehumidification mode if the current average humidity of the cold storage is greater than the set humidity. In the dehumidification mode, the storage temperature set value and the evaporation temperature of the refrigeration unit are reduced to the set temperature in the dehumidification mode. The set temperature in the dehumidification mode is a temperature automatically reduced by a controller according to the current storage temperature and the storage temperature set value floating setting. The opening of the electronic expansion valve is controlled according to the current temperature of the cold storage and the rate of decrease of the cold storage temperature. The output frequency of the compressor is adjusted according to the suction pressure and the rate of decrease of the suction pressure. The speed of the air supply fan is controlled according to the current temperature of the cold storage and the current output frequency of the compressor. During the dehumidification process, if the current temperature of the cold storage is lower than the set protection temperature, the heater is started and the PID method is used to control the heater; if the current average humidity of the cold storage is less than the set humidity, the dehumidification is turned off;

[0075] The defrost control method includes defrost judgment, if the cumulative refrigeration operation time of the unit reaches a set cycle and the temperature of the fin is lower than the set defrost temperature, the defrost mode is entered, and when the fin temperature is higher than the defrost termination temperature or the defrost time is greater than the set maximum defrost time, the defrost is terminated;

[0076] The priority level of the defrost mode is greater than the priority level of refrigeration, and the priority level of refrigeration is greater than the priority level of initial dehumidification.

[0077] The PID method is an existing mature control method that can ensure the stability of warehouse temperature.

[0078] The temperature control method can ensure that the superheat is maintained within a stable range. Through the above control, the best energy-saving effect can be achieved while quickly controlling the temperature.

[0079] The humidity control method can ensure that the temperature change is controlled within the set range during dehumidification. At the same time, when the temperature is lower than the lower limit of the warehouse temperature setting value, the electric heater is controlled to work to maintain the fluctuation range of the warehouse temperature.

[0080] The calculation of the defrost cycle and time in the defrost control method can be dynamically adjusted according to the operation history records, thereby improving the defrost effect of the evaporator and reducing the energy consumption of defrost.

[0081] Dehumidification requires moisture to condense or frost on the dehumidifier fins, and then turn into water and discharge to the outside. Therefore, cooling is still required during dehumidification. Since the temperature is lower than the refrigeration working point at this time, the refrigeration system needs to be forced to work, such as by lowering the refrigeration set point. In order to control the warehouse temperature, it is necessary to reduce the compressor frequency, reduce the refrigerant supply (reduce the opening of the expansion valve) and reduce the speed of the supply fan, so that the compressor only outputs part of the cooling capacity, and turn on the heating wire to maintain the warehouse temperature.

[0082] The set temperature in dehumidification mode is determined by the program. After detecting the current storage temperature and comparing it with the set storage temperature, the program gradually reduces the set value. In order to ensure the quality and safety of the goods in the cold storage, the controller sets a minimum protection temperature. When the storage temperature is lower than this temperature, dehumidification will stop and continue after the storage temperature rises.

[0083] The falling speed of the warehouse temperature is obtained by regularly collecting temperature values ​​and calculating the difference with the last temperature collection value, storing the difference regularly, and regularly comparing the difference with the last difference. The calculation of the falling speed of the suction pressure is similar.

[0084] The floating setting is set by the program. The frequency adjustment amplitude (adjustment value) is calculated according to the interval of the suction pressure and the speed of the suction pressure drop. The frequency is adjusted every 5 seconds.

[0085] The set point corresponding to the suction pressure greater than Ts1 is the loading zone, the pressure point corresponding to the pressure less than Ts2 is the unloading zone, and the neutral zone is between them. If the frequency is increased once every 5 seconds in the loading zone, the frequency is reduced once every 5 seconds in the unloading zone, and the original frequency is maintained in the neutral zone. The modified parameters are set according to the suction pressure change speed (sampling period 5s) and frequency change value of the last adjustment, combined with the system operating conditions and experience coefficients. Ensure that the suction pressure quickly reaches and is maintained in the neutral zone.

[0086] The regulation of the speed of the electronic expansion valve and the fan is simplified as follows: if the pressure of the electronic expansion valve is lower than the shutdown pressure point during dehumidification, the electronic expansion valve is completely closed.

[0087] The speed of the air supply fan motor is proportional to the output frequency of the compressor, but the maximum speed is limited to 40% of the full speed.

[0088] The heating box is equipped with a power regulator. When the heating is started, the power of the heating wire is gradually adjusted according to the change of the hot storage temperature to ensure the stability of the cold storage temperature.

[0089] Defrosting is performed through the defrosting electric heating wire on the back of the evaporator in the temperature and humidity integrated machine.

[0090] In the cooling mode, the frequency adjustment float of the compressor is calculated according to the deviation interval between the suction pressure and the corresponding evaporation pressure at the set evaporation temperature, and the output speed of the compressor is adjusted according to the set frequency adjustment interval; the amplitude of the compressor frequency adjustment is:

[0091] f=f1*(P-P0) / (P1-P0),

[0092] P0 = 0.5 * (P1 + P2);

[0093] f1 is the frequency modulation coefficient;

[0094] P is the measured value of the suction pressure;

[0095] P1 is the saturated gas pressure corresponding to the set refrigeration temperature T1;

[0096] P2 is the saturated gas pressure corresponding to the set refrigeration temperature T2.

[0097] Also included is a compressor frequency modulation amplitude correction, which is used to recalculate the amplitude of the compressor frequency regulation:

[0098] t=a*t1,

[0099] In the formula,

[0100] a is the correction value of the sampling adjustment cycle, which is calculated according to the decreasing speed of the suction pressure and is used to change the time interval of the adjustment frequency;

[0101] t1 is the set frequency modulation interval.

[0102] Specifically, the cold storage refrigeration control method includes the following steps:

[0103] S101: After the refrigeration unit is started, a defrost judgment is first performed. If the cumulative refrigeration operation time of the unit reaches the set cycle and the temperature of the fins is lower than the set defrost temperature, enter S201. If the defrost conditions are not met, enter S102. After the refrigeration unit is started, three thermometers and three hygrometers are first detected, and the average temperature and average humidity are calculated. At the same time, the defrost temperature, alarm signal, suction pressure and suction temperature, exhaust pressure and exhaust temperature are detected.

[0104] S102, detect the current temperature of the cold storage, and calculate the average temperature of multiple temperature sensors. If the current average temperature T0 of the cold storage is greater than the set temperature Ts1 of the cold storage, enter S103; if the current temperature T0 of the cold storage is less than the set temperature Ts1, enter S106; when one or two temperature sensors fail, take the reading values ​​of the temperature sensors that have not failed to calculate the average value;

[0105] S103, entering the cooling mode, in which the air supply fan rotates at the highest speed, the opening of the electronic expansion valve is controlled according to the suction superheat, and the output frequency of the compressor is adjusted;

[0106] The set point corresponding to the suction pressure greater than Ts1 is the loading zone, that is, the refrigeration output begins to increase. The pressure point corresponding to the suction pressure less than Ts2 is the unloading zone, that is, the refrigeration output begins to decrease. The suction pressure between the two is the neutral zone. The neutral zone keeps the cold storage temperature constant by adjusting the frequency of the variable frequency compressor. If the frequency is increased once every 5 seconds in the loading zone, the frequency is reduced once every 5 seconds in the unloading zone, and the original frequency is maintained in the neutral zone. The modified parameters are set according to the suction pressure change speed (sampling period 5s) and frequency change value adjusted last time, combined with the system operating conditions and experience coefficients. Ensure that the suction pressure quickly reaches and is maintained in the neutral zone.

[0107] Ts1 is the set cold storage temperature, and Ts2 is Ts1 minus a lower deviation, which corresponds to the refrigeration stop temperature.

[0108] In the cooling mode, the frequency adjustment float of the compressor is calculated according to the deviation interval between the suction pressure and the corresponding evaporation pressure at the set evaporation temperature, and the output speed of the compressor is adjusted according to the set frequency modulation interval; the amplitude of the compressor frequency adjustment: f = f1*(P-P0) / (P1-P0), P0 = 0.5*(P1+P2); f1 is the frequency modulation coefficient; P is the measured value of the suction pressure; P1 is the saturated gas pressure corresponding to the set refrigeration temperature T1; P2 is the saturated gas pressure corresponding to the set refrigeration temperature T2.

[0109] Compressor frequency modulation amplitude correction, the compressor frequency modulation amplitude correction is used to recalculate the amplitude of the compressor frequency regulation: t=a*t1, where a is the correction value of the sampling regulation period, which is calculated according to the drop rate of the suction pressure and is used to change the time interval of the regulation frequency.

[0110] S104, detecting whether the refrigeration operation time reaches the defrost cycle, if it reaches the defrost cycle, entering S101, if it does not enter the defrost cycle, entering S105;

[0111] S105, check whether the current cold storage temperature is less than Ts2, if it is less than Ts2, enter S106, if it is greater than Ts2, enter S103 to continue cooling;

[0112] S106, stop refrigeration and enter S107;

[0113] S107, detect the current humidity H0 of the cold storage, if the current humidity H0 is greater than the set humidity H1, enter S108, if the current humidity H0 is less than the set humidity H1, enter S101;

[0114] S108, enter the dehumidification mode for dehumidification, reduce the evaporation temperature to -35℃ or dynamically modify it according to the storage temperature setting value, adjust the opening of the electronic expansion valve according to the storage temperature and the speed of the storage temperature drop, adjust the operating frequency of the compressor according to the suction pressure and its drop speed and the terminal control signal, and the fan speed is controlled according to the storage temperature and the frequency of the compressor. In the dehumidification process, it is also necessary to enter S301 and S109;

[0115] S109, detecting whether the transportation time reaches the defrost cycle, if so, proceeding to S101, if not, proceeding to S110;

[0116] S110, detect the current humidity of the cold storage, if the current humidity H0 is not greater than the set humidity H1, enter S111, if the current humidity is greater than the set humidity, enter S108;

[0117] S111, dehumidification is completed, return to S101;

[0118] in,

[0119] S201, defrost mode, when entering the defrost mode, refrigeration, dehumidification and heating are all stopped, the heating wire on the evaporator is heated to defrost, and then enter S202;

[0120] S202, detecting whether the defrost termination condition is met, if the fin temperature is higher than the defrost termination temperature or the defrost time is longer than the set defrost time, then entering S203, otherwise entering S201;

[0121] S203, defrosting is terminated and the process goes to S102;

[0122] S301: During the dehumidification process, if the current temperature T0 of the cold storage is lower than the set protection temperature Ts3, then enter S302; if the current temperature T0 is greater than the set protection temperature Ts3, then enter S101. Entering S101 means that if there is no defrosting or refrigeration, if the humidity is still higher than the set value, the next step is to continue dehumidification;

[0123] S302, heating mode, start the heater and use the PID method to control the heater, and then enter S303;

[0124] S303, detect whether dehumidification is finished, if dehumidification is finished, enter S305, if dehumidification is not finished, enter S304, where the dehumidification is finished when the humidity is less than H2 (set value H1-deviation). If the current average humidity of the cold storage is less than the set humidity H2, the dehumidification is turned off;

[0125] S304, if the current temperature T0 is greater than temperature Ts4, then enter S305; if the current temperature T0 is not greater than temperature Ts4, then enter S301, Ts4 is the heating stop temperature, which is lower than the cooling set temperature Ts1, Ts4 and Ts3 constitute a heating interval, and heating is maintained within this interval;

[0126] S305, the heating mode ends, the system enters the standby mode, and then enters S101.

Claims

1. A cold storage refrigeration control method, characterized in that: include: A temperature control method, the temperature control method comprising calculating the current average temperature of the cold storage according to the temperatures measured by a plurality of temperature sensors, and entering a refrigeration mode if the current average temperature of the cold storage is greater than a set temperature, wherein the air supply fan rotates at a maximum speed, the opening of the electronic expansion valve is controlled according to the suction superheat, and the output frequency of the compressor is adjusted; if the current average temperature of the cold storage is less than the set temperature, the refrigeration is turned off; A humidity control method, the humidity control method comprising calculating the current average humidity of the cold storage according to the humidity measured by a plurality of humidity sensors, and entering a dehumidification mode if the current average humidity of the cold storage is greater than a set humidity, wherein the storage temperature set value and the evaporation temperature of the refrigeration unit are reduced to the set temperature in the dehumidification mode, and the set temperature in the dehumidification mode is a temperature automatically reduced by a controller according to the current storage temperature and the storage temperature set value floating setting, and the opening of the electronic expansion valve is controlled according to the current temperature of the cold storage and the falling speed of the cold storage temperature, and the output frequency of the compressor is adjusted according to the suction pressure and the falling speed of the suction pressure, and the speed of the air supply fan is controlled according to the current temperature of the cold storage and the current output frequency of the compressor, and during the dehumidification process, if the current temperature of the cold storage is lower than the set protection temperature, the heater is started and the heater is controlled by the PID method; if the current average humidity of the cold storage is lower than the set humidity, the dehumidification is turned off; The defrost control method includes defrost judgment, if the cumulative refrigeration operation time of the unit reaches a set cycle and the temperature of the fin is lower than the set defrost temperature, the defrost mode is entered, and when the fin temperature is higher than the defrost termination temperature or the defrost time is greater than the set maximum defrost time, the defrost is terminated; The priority level of the defrost mode is higher than the priority level of refrigeration, and the priority level of refrigeration is higher than the priority level of initial dehumidification; In the cooling mode, the frequency adjustment amplitude of the compressor is calculated according to the deviation interval between the suction pressure and the corresponding evaporation pressure at the set evaporation temperature, and the output speed of the compressor is adjusted according to the set frequency modulation interval; The frequency adjustment range of the compressor is: f=f1*(P-P0) / (P1-P0), P0=0.5*(P1+P2); f1 is the frequency modulation coefficient; P is the measured value of the suction pressure; P1 is the saturated gas pressure corresponding to the set refrigeration temperature T1; P2 is the saturated gas pressure corresponding to the set refrigeration temperature T2; Wherein, the cold storage is a cube, including A cold storage air outlet device, wherein the cold storage air outlet device is installed at the four corners of the top of the cold storage; Temperature sensors, there are no less than three temperature sensors, the temperature sensors are installed on the diagonal lines of the cold storage and are evenly arranged, and the temperature sensors are not located at the air outlets and corners of the cold storage; Humidity sensors, there are no less than three humidity sensors, the humidity sensors are arranged along the length direction of the cold storage, and the humidity sensors are respectively located in the middle and bottom of the height direction of the cold storage, and the humidity sensors are not located at the air outlet and the corners of the cold storage; A defrost temperature sensor, wherein the defrost temperature sensor is installed on the evaporator; Inspiratory pressure sensor; A variable frequency compressor, the evaporator is connected to the variable frequency compressor, and the suction pressure sensor is installed on the pipeline between the evaporator and the variable frequency compressor; A condenser, wherein the condenser is connected to the variable frequency compressor; An electronic expansion valve, wherein the electronic expansion valve is connected to the condenser and the evaporator respectively; A PLC controller, wherein the temperature sensor, humidity sensor, defrost temperature sensor, suction pressure sensor, variable frequency compressor, electronic expansion valve, air supply fan and heater are all connected to the PLC controller; The cold storage has a length of 40-50 meters, a width of 4-7 meters, and a height of 10-13 meters; The distance between the air outlet of the cold storage air outlet device and the side wall of the cold storage end is 1-1.4 meters, and the distance between the air outlet and the side wall of the cold storage side is 1-1.3 meters; The cold storage air outlet device includes an air supply fan, an evaporator and a heater; and also includes: A heating box, wherein the heater is installed inside the heating box, and the evaporator is installed at one end of the heating box; An air outlet box, wherein the air outlet box is provided with an air inlet and an air outlet, and the air inlet is installed at the other end of the heating box; The air supply fan is installed at one end of the evaporator located in the heating box or on the air outlet box, and the air supply fan is used to blow the air out from the air outlet of the air outlet box after passing through the evaporator and the heater; The axis of the air outlet is parallel, perpendicular or intersecting with the axis of the airflow direction of the evaporator; An evaporation casing, wherein the evaporator is installed in the evaporation casing; A defrost water receiving tray, wherein the defrost water receiving tray is arranged at the bottom of the evaporation casing; The heater is an electric heating tube; It also includes a power regulator, which is connected to the electric heating tube; The air supply fan is a speed-regulating fan.

2. The cold storage refrigeration control method according to claim 1, characterized in that: Also included is a compressor frequency modulation amplitude correction, which is used to recalculate the amplitude of the compressor frequency regulation: t=a*t1, In the formula a is the correction value of the sampling adjustment cycle, which is calculated according to the decreasing speed of the suction pressure and is used to change the time interval of the adjustment frequency; t1 is the set frequency modulation interval.

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