A control system for a dual frequency variable grain cooler

Abstract

The utility model discloses a control system for double frequency change grain cooler relates to the technical field of grain cooler of grain storage, and it is including: the output of frequency conversion compressor connects condenser, and the export of condenser is connected with throttling device and evaporator in proper order, and the output of evaporator is connected with the input of frequency conversion compressor, the input of reheater is connected with the output of frequency conversion compressor, and the output of reheater is connected with the input of throttling device, evaporator, reheater, centrifugal fan are set gradually in front of the air supply opening of air inlet channel along the air circulation order, and the air supply opening of air inlet channel is connected with the air inlet of granary, the controller is installed in the control cabinet of grain cooler, and the controller is connected with frequency conversion compressor, centrifugal fan electricity respectively, the utility model discloses can improve the utilization of equipment cold quantity and ventilation operation efficiency, guarantee the continuity of ventilation operation, overcome the problem of the big fluctuation of cold quantity, the unstable problem of outlet air temperature and humidity caused by traditional fixed frequency compressor unloading.

Description

Technical Field

[0001] This utility model relates to the technical field of grain coolers for grain storage, and more specifically to a control system for a dual-frequency conversion grain cooler. Background Technology

[0002] The function of a grain cooler is to supply cold air at a constant temperature and humidity to grain piles. To cope with changes in ambient temperature and humidity, current equipment mainly uses a method of constant cooling capacity (multiple sets of fixed-frequency compressors) and variable air volume (frequency-controlled fans) to ensure stable outlet air temperature and humidity. This method is adaptable to a wide range of environments. In environments with relatively high temperature and humidity, when the cooling capacity is relatively insufficient, the air volume is reduced to control the stability of the outlet air temperature and humidity. In environments with relatively low temperature and humidity, when the cooling capacity is relatively excessive, and the fans reach their maximum air volume, one or more systems must be shut down to reduce the cooling capacity, and the fans are adjusted from maximum air volume to a smaller air volume to ensure stable outlet air temperature.

[0003] The main problem with this method is that, even if there is remaining cooling capacity, at least the entire system must be unloaded. This results in a significant reduction in cooling capacity and large fluctuations in the outlet air temperature. In order to ensure a stable outlet air temperature, the system can only ventilate at a low air volume, which cannot fully utilize the cooling capacity of the equipment and reduces the efficiency of the cooling and ventilation operation.

[0004] Therefore, how to improve the utilization rate of equipment cooling capacity and the efficiency of ventilation operations is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] In view of this, the present invention provides a control system for a dual-frequency conversion grain cooler, which solves the problems existing in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: A control system for a dual-frequency grain cooler includes: a frequency converter compressor, a condenser, a throttling device, an evaporator, a reheater, a centrifugal fan, and a controller; The output end of the variable frequency compressor is connected to the condenser, and the outlet of the condenser is connected in sequence to the throttling device and the evaporator. The output end of the evaporator is connected to the input end of the variable frequency compressor. The input end of the reheater is connected to the output end of the variable frequency compressor, and the output end of the reheater is connected to the input end of the throttling device. The evaporator, reheater, and centrifugal fan are arranged in sequence in front of the air outlet of the air inlet channel, following the air flow order. The air outlet of the air inlet channel is connected to the air inlet of the grain silo. The controller is installed in the control cabinet of the grain cooler and is electrically connected to the variable frequency compressor and the centrifugal fan respectively.

[0007] Optionally, the condenser uses an EC variable frequency axial flow fan for heat dissipation, and the EC variable frequency axial flow fan is electrically connected to the controller.

[0008] Optionally, the throttling device includes a liquid storage tank and an expansion valve. The outlet of the condenser is connected to the liquid storage tank, and the liquid storage tank is connected to the evaporator through the expansion valve.

[0009] Optionally, a regulating valve is provided between the reheater and the throttling device, and the regulating valve is electrically connected to the controller.

[0010] Optionally, an air inlet temperature sensor is installed at the air inlet of the air inlet channel, a front temperature sensor is installed between the evaporator and the reheater, and an air outlet temperature sensor is installed at the air outlet of the air inlet channel. All three sensors are electrically connected to the controller.

[0011] Optionally, the centrifugal fan is controlled by a frequency converter circuit.

[0012] Optionally, an electric heating device is installed between the reheater and the centrifugal fan.

[0013] Optionally, the air inlet of the air inlet duct is connected to the return air chamber, and a filter screen is installed between the return air chamber and the evaporator.

[0014] As can be seen from the above technical solution, compared with the prior art, this utility model discloses a control system for a dual-frequency conversion grain cooler, which has the following beneficial effects: (1) The use of a variable frequency compressor can achieve stepless adjustment, which overcomes the problem of large fluctuations in cooling capacity and unstable outlet air temperature and humidity caused by unloading of the fixed frequency compressor in traditional equipment; (2) The use of variable frequency compressors and centrifugal fans with fixed frequency and large air volume ventilation control improves the utilization rate of equipment cooling capacity and ventilation operation efficiency; (3) The condenser fan adopts an EC variable frequency fan, which can automatically adjust the heat dissipation air volume according to the working status of the compressor after the frequency conversion, thus ensuring the stability of the refrigeration system; (4) The frequency conversion function of the fan is retained, which ensures the continuity of ventilation operation when the cooling capacity of the system is insufficient in high temperature and high humidity environment, and improves the adaptability of the equipment to the environment. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1A structural diagram of the control system for a dual-frequency conversion grain cooler provided by this utility model; Attached reference numerals: 1-Variable frequency compressor, 2-Condenser, 3-Evaporator, 4-Reheater, 5-Centrifugal fan, 6-EC variable frequency axial fan, 7-Liquid receiver, 8-Expansion valve, 9-Regulating valve, 10-Air inlet, 11-Inlet air temperature sensor, 12-Pre-temperature sensor, 13-Air outlet, 14-Outlet air temperature sensor, 15-Return air chamber, 16-Filter screen, 17-Motor. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] To overcome the problem that traditional grain coolers, under relatively low ambient temperature and humidity conditions, suffer from excessive reduction in cooling capacity due to system unloading, resulting in low-volume ventilation and inefficient cooling operations, this utility model discloses a control system for a dual-frequency conversion grain cooler, such as... Figure 1 As shown, it includes: a variable frequency compressor 1, a condenser 2, a throttling device, an evaporator 3, a reheater 4, a centrifugal fan 5, and a controller; The output end of the variable frequency compressor 1 is connected to the condenser 2. The outlet of the condenser 2 is connected in sequence to the throttling device and the evaporator 3. The output end of the evaporator 3 is connected to the input end of the variable frequency compressor 1. The input end of reheater 4 is connected to the output end of variable frequency compressor 1, and the output end of reheater 4 is connected to the input end of throttling device; Evaporator 3, reheater 4, and centrifugal fan 5 are arranged in sequence in front of air outlet 13 in the air inlet channel, following the air flow sequence. Air outlet 13 in the air inlet channel is connected to the air inlet of the grain silo. Centrifugal fan 5 is connected to motor 17. The controller is installed inside the control cabinet of the grain cooler and is electrically connected to the variable frequency compressor 1 and the centrifugal fan 5. The controller is located outside the air intake duct and does not directly participate in the air circulation and heat exchange process within the air intake duct; it only interacts with the components through electrical signals.

[0019] Furthermore, the condenser 2 uses an EC variable frequency axial flow fan 6 for heat dissipation, and the EC variable frequency axial flow fan 6 is electrically connected to the controller.

[0020] Furthermore, the throttling device includes a liquid storage tank 7 and an expansion valve 8. The outlet of the condenser 2 is connected to the liquid storage tank 7, and the liquid storage tank 7 is connected to the evaporator 3 through the expansion valve 8.

[0021] Furthermore, a regulating valve 9 is provided between the reheater 4 and the throttling device, and the regulating valve 9 is electrically connected to the controller.

[0022] Furthermore, an air inlet temperature sensor 11 is installed at the air inlet 10 of the air inlet channel, a front temperature sensor 12 is installed between the evaporator 3 and the reheater 4, and an air outlet temperature sensor 14 is installed at the air outlet 13 of the air inlet channel. The air inlet temperature sensor 11, the front temperature sensor 12, and the air outlet temperature sensor 14 are all electrically connected to the controller.

[0023] In this embodiment, the controller, as the core hub of the entire control system, can receive temperature signals collected by the inlet air temperature sensor 11, the front temperature sensor 12, and the outlet air temperature sensor 14. According to the preset control logic, it sends control commands to the variable frequency compressor 1, the centrifugal fan 5, the EC variable frequency axial flow fan 6, and the regulating valve 9 to adjust the cooling capacity, air volume, and medium flow rate, thereby achieving stable control of the outlet air temperature and humidity and ensuring the efficiency and continuity of ventilation operations.

[0024] Furthermore, the centrifugal fan 5 is controlled by a frequency converter circuit.

[0025] Furthermore, an electric heating device is installed between the reheater 4 and the centrifugal fan 5.

[0026] Furthermore, the air inlet 10 of the air inlet channel is connected to the return air chamber 15, and a filter screen 16 is provided between the return air chamber 15 and the evaporator 3.

[0027] Based on the above structural design, the working principle of the control system for the dual-frequency grain cooler proposed in this embodiment can be understood as follows: In the grain cooler system, the variable frequency compressor 1 sends the high-temperature and high-pressure refrigerant to the condenser 2 and the reheater 4 respectively. After being cooled by the condenser 2, the refrigerant becomes a low-temperature refrigerant. The low-temperature refrigerant enters the liquid storage tank 7 and then enters the evaporator 3 after passing through the electronic expansion valve 8 and other filtering and throttling devices. After the evaporator 3 exchanges heat with the hot air in the air inlet channel, the refrigerant is heated and enters the variable frequency compressor 1, re-entering the refrigeration cycle.

[0028] When the grain cooler is performing refrigeration and ventilation operations, the air outlet of the grain cooler is connected to the air inlet 10 of the grain silo. Ambient air enters from the air inlet 10 and undergoes heat exchange when passing through the evaporator 3. The hot air becomes cold air with a relatively high humidity. After passing through the reheater 4 again, it is reduced to cold air with the required relative humidity. The cold air is then sent into the grain pile by the centrifugal fan 5 through the air outlet 13.

[0029] Unlike traditional grain coolers, in this embodiment, the centrifugal fan 5 is set to operate at a fixed high frequency and large air volume to ensure ventilation efficiency. During normal operation, the frequency (cooling capacity) of the variable frequency compressor 1 is adjusted to ensure stable outlet air temperature. When the ambient temperature and humidity decrease, and the temperature detected by the front temperature sensor 12 is lower than the target temperature, the control system appropriately lowers the operating frequency of the variable frequency compressor 1 in a variable frequency mode to keep the temperature at the front temperature sensor 12 consistent with the target temperature. After heating and dehumidification by the reheater 4, the stability of outlet air temperature and humidity is ensured. When the ambient temperature and humidity increase, and the temperature detected by the front temperature sensor 12 is higher than the target temperature, the control system appropriately raises the operating frequency of the variable frequency compressor 1 in a variable frequency mode to keep the temperature at the front temperature sensor 12 consistent with the target temperature. To maintain consistency, the reheater 4 heats up and dehumidifies, ensuring stable outlet air temperature and humidity. Meanwhile, the centrifugal fan 5 maintains high-frequency, high-volume operation, improving the efficiency of refrigeration and ventilation. When the ambient temperature and humidity continue to rise, the frequency of the variable frequency compressor 1 reaches its maximum, and the temperature detected by the front temperature sensor 12 is still higher than the target temperature, the cooling capacity of the equipment is insufficient to meet the system requirements. Therefore, the operating frequency of the centrifugal fan 5 must be reduced to decrease the air volume. At this time, the variable frequency compressor 1 maintains its maximum frequency operation, and the temperature at the front temperature sensor 12 is stabilized by adjusting the frequency of the centrifugal fan 5. This maintains the same operating mode as a traditional grain cooler.

[0030] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0031] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control system for a dual-frequency conversion grain cooler, characterized in that, include: Variable frequency compressors, condensers, throttling devices, evaporators, reheaters, centrifugal fans, and controllers; The output end of the variable frequency compressor is connected to the condenser, and the outlet of the condenser is connected in sequence to the throttling device and the evaporator. The output end of the evaporator is connected to the input end of the variable frequency compressor. The input end of the reheater is connected to the output end of the variable frequency compressor, and the output end of the reheater is connected to the input end of the throttling device. The evaporator, reheater, and centrifugal fan are arranged in sequence in front of the air outlet of the air inlet channel, following the air flow order. The air outlet of the air inlet channel is connected to the air inlet of the grain silo. The controller is installed in the control cabinet of the grain cooler and is electrically connected to the variable frequency compressor and the centrifugal fan respectively.

2. The control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, The condenser uses an EC variable frequency axial flow fan for heat dissipation, and the EC variable frequency axial flow fan is electrically connected to the controller.

3. The control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, The throttling device includes a liquid storage tank and an expansion valve. The outlet of the condenser is connected to the liquid storage tank, and the liquid storage tank is connected to the evaporator through the expansion valve.

4. The control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, A regulating valve is installed between the reheater and the throttling device, and the regulating valve is electrically connected to the controller.

5. A control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, An air inlet temperature sensor is installed at the air inlet of the air inlet channel, a front temperature sensor is installed between the evaporator and the reheater, and an air outlet temperature sensor is installed at the air outlet of the air inlet channel. All three sensors are electrically connected to the controller.

6. The control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, The centrifugal fan is controlled by a frequency converter circuit.

7. A control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, An electric heating device is installed between the reheater and the centrifugal fan.

8. A control system for a dual-frequency conversion grain cooler according to claim 1, characterized in that, The air inlet of the air inlet duct connects to the return air chamber, and a filter screen is installed between the return air chamber and the evaporator.

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