Supercooling auxiliary type sludge heat pump drying device and control method

Abstract

This invention relates to the field of sludge heat pump drying equipment technology, and more particularly to a subcooling-assisted sludge heat pump drying device, comprising: a refrigerant circuit subsystem, which includes a compressor, a main condenser, a refrigerant regenerator, an expansion valve, and an evaporator. The high-pressure outlet of the refrigerant regenerator is connected to at least two parallel circuits, one of which is equipped with a subcooling component that uses condensate and / or ambient air to subcool the refrigerant, and the other circuit is equipped with an on / off control component. By switching the on / off state of the two circuits and the operating state of the subcooling component, selective subcooling of the refrigerant at the outlet of the main condenser is achieved. By setting up the subcooling component, the subcooling of the refrigerant using condensate and / or ambient air is realized, making full use of the cooling capacity of the condensate and ambient air generated during the operation of the device, solving the problem of direct discharge of condensate and waste of cooling capacity in traditional devices, and improving energy utilization efficiency.

Description

Technical Field

[0001] This invention relates to the field of sludge heat pump drying equipment technology, and in particular to a subcooling-assisted sludge heat pump drying device and control method. Background Technology In the field of drying high-moisture materials such as sludge, heat pump drying devices have been widely promoted and applied due to their significant advantages such as low energy consumption, convenient operation, and stable operation. In existing technologies, typical sludge heat pump drying devices generally adopt a closed-loop air circulation structure. The core operating process is as follows: air flows through the main condenser under the action of circulation power, absorbs the heat released by the refrigerant, and then enters the drying chamber to dry the sludge. After completing the drying task, the high-humidity air leaving the drying chamber flows through the evaporator, where it is cooled and dehumidified. The condensate generated during this process is directly discharged from the system. The dehumidified low-temperature air flows back to the inlet of the main condenser to be reheated, thus forming a closed-loop cycle and achieving continuous sludge drying.

[0002] However, traditional sludge heat pump drying devices have shortcomings in actual operation that restrict the energy efficiency of the device. On the one hand, the heat input to the air circuit of the heat pump system is always greater than the cooling input, resulting in an imbalance of heating and cooling loads and excess heat within the system. To ensure the system can operate stably for a long time, existing technologies usually use an external waste heat condenser to balance the system load by directly discharging excess heat. However, this design wastes some of the effective heating capacity generated by the heat pump, indirectly reducing the overall energy efficiency of the device, which contradicts the current industry development needs for energy conservation and emission reduction. On the other hand, the condensate produced by the evaporator during the cooling and dehumidification process carries a certain amount of low-temperature cooling capacity. However, existing technologies all use the method of directly discharging condensate, failing to recover and utilize this cooling capacity, resulting in a waste of cooling capacity. Summary of the Invention

[0003] To address the above problems, this application provides a subcooled assisted sludge heat pump drying device, comprising: a refrigerant circuit subsystem, a condensate circuit subsystem, an air circuit subsystem, and a control subsystem; the refrigerant circuit subsystem includes a compressor, a main condenser, a refrigerant regenerator, an expansion valve, and an evaporator; the high-pressure outlet of the refrigerant regenerator is connected to at least two parallel circuits, one of which is equipped with a subcooling component that uses condensate and / or ambient air to subcool the refrigerant, and the other circuit is equipped with an on / off control component; by switching the on / off state of the two circuits and the operating state of the subcooling component, selective subcooling of the refrigerant at the outlet of the main condenser is achieved; the control subsystem is used to control the subcooling method of the refrigerant by the subcooling component according to the device operating parameters.

[0004] In one embodiment, the subcooling assembly includes a water subcooler, an air subcooler, and a first three-way valve, and the on / off control assembly is a shut-off valve; of the two parallel circuits connected to the high-pressure outlet of the refrigerant regenerator, one circuit is divided into a first branch and a second branch through the first three-way valve. In the first branch, the high-pressure outlet of the refrigerant regenerator is sequentially connected to the water subcooler and the air subcooler, and in the second branch, the high-pressure outlet of the refrigerant regenerator is directly connected to the air subcooler. The other circuit is connected to the inlet of the expansion valve through the shut-off valve; the outlet of the air subcooler is connected to the inlet of the expansion valve.

[0005] In one embodiment, the refrigerant circuit subsystem further includes a waste heat condenser and a second three-way valve. The air subcooler is equipped with a variable frequency air subcooler fan, the waste heat condenser is equipped with a variable frequency waste heat condenser fan, and the compressor is a variable frequency compressor. The compressor exhaust port is connected to the inlet of the second three-way valve, and the two outlets of the second three-way valve are respectively connected to the refrigerant inlet of the main condenser and the refrigerant inlet of the waste heat condenser. The refrigerant outlet of the main condenser is connected to the high-pressure liquid inlet of the refrigerant regenerator, and the refrigerant outlet of the waste heat condenser is connected to the high-pressure liquid inlet of the refrigerant regenerator. The expansion valve outlet is connected to the refrigerant inlet of the evaporator, the refrigerant outlet of the evaporator is connected to the low-pressure suction port of the refrigerant regenerator, and the low-pressure exhaust port of the refrigerant regenerator is connected to the compressor suction port.

[0006] In one embodiment, the condensate circuit subsystem includes a water receiving pan, an insulated water tank, a condensate pump, a drain valve, and a water subcooler shared with the refrigerant circuit subsystem. The water receiving pan is located below the evaporator and connected to the insulated water tank via a pipe. The insulated water tank is connected in sequence to the condensate pump and the water-side inlet of the water subcooler via pipes. The bottom of the insulated water tank is connected to the inlet of the drain valve via a pipe. The outlet of the drain valve is connected to a drain pipe. The water-side outlet of the water subcooler is connected to a drain pipe.

[0007] In one embodiment, the air circuit subsystem includes a circulating fan, a drying chamber, an air regenerator, and a main condenser and evaporator shared with the refrigerant circuit subsystem. The outlet of the circulating fan is connected to the air inlet of the drying chamber, the air outlet of the drying chamber is connected to the hot air inlet of the air regenerator, the hot air outlet of the air regenerator is connected to the air inlet of the evaporator, the air outlet of the evaporator is connected to the cold air inlet of the air regenerator, the cold air outlet of the air regenerator is connected to the air inlet of the main condenser, and the air outlet of the main condenser is connected to the inlet of the circulating fan.

[0008] In one embodiment, the control subsystem includes a controller, a first temperature sensor located at the high-pressure outlet of the refrigerant regenerator, a second temperature sensor located at the outlet of the insulated water tank, a third temperature sensor located at the refrigerant outlet of the air subcooler, a fourth temperature sensor located at the refrigerant outlet of the water subcooler, a fifth temperature sensor for measuring ambient temperature, and a sixth temperature sensor located at the air inlet of the drying chamber. Each temperature sensor is connected to the signal input terminal of the controller.

[0009] In one embodiment, the signal output terminal of the controller is connected to the compressor, the shut-off valve, the condensate pump, the circulating fan, the air subcooler fan, the waste heat condenser fan, the first three-way valve, and the second three-way valve, and is configured to control the start / stop, frequency, or opening degree of the components based on the measured values ​​of each temperature sensor.

[0010] A control method for a subcooled assisted sludge heat pump drying device, comprising four operating modes: no subcooling mode (M1), pure water subcooling mode (M2), pure air subcooling mode (M3), and water-air composite subcooling mode (M4). The ambient temperature corresponding to the complete closure of the second three-way valve on the waste heat condenser side is defined as the critical ambient temperature T55c. The ambient temperature setpoint is set to T55s, and the air inlet temperature setpoint for the drying chamber is set to T56s. The operating conditions for the four modes are as follows: It can operate in non-subcooling mode (M1) under any conditions; When the ambient temperature T55 is greater than 0℃ and the outlet water temperature T52 of the insulated water tank is less than the high-pressure outlet temperature T51 of the refrigerant regenerator, the pure water subcooling mode (M2) can be operated. When the ambient temperature T55 is less than the ambient temperature setpoint T55s, the pure air subcooling mode (M3) can be run. When the ambient temperature T55 is greater than 0℃, the outlet water temperature T52 of the insulated water tank is less than the high-pressure outlet temperature T51 of the refrigerant regenerator, and the ambient temperature T55 is less than the refrigerant outlet temperature T54 of the water subcooler, the water-air composite subcooling mode (M4) can be operated; each mode stabilizes T56 to T56s by adjusting the relevant components.

[0011] In one embodiment, the control operation of the non-subcooling mode (M1) is as follows: the compressor, circulating fan and waste heat condenser fan operate at the rated frequency, the air subcooler fan does not operate, the condensate pump does not operate, the shut-off valve is opened, the drain valve is opened, the first three-way valve is adjusted so that the first branch and the second branch are both closed, and the opening degree of the second three-way valve is adjusted to stabilize at the set value T56s. The control operation of the pure water subcooling mode (M2) is as follows: the circulating fan and the waste heat condenser fan operate at the rated frequency, the air subcooler fan does not operate, the condensate pump operates at the rated frequency, the shut-off valve is closed, the drain valve is closed, the first three-way valve is adjusted to open the first branch and close the second branch, and the compressor frequency and the opening of the second three-way valve are adjusted to stabilize at the set value T56s. The control operation of the pure air subcooling mode (M3) is as follows: When the ambient temperature T55 is greater than the critical ambient temperature T55c, the circulating fan, waste heat condenser fan and air subcooler fan operate at the rated frequency, the condensate pump does not operate, the shut-off valve is closed, the drain valve is opened, the first three-way valve is adjusted to close the first branch and open the second branch, and the compressor frequency and the opening of the second three-way valve are adjusted to stabilize at the set value T56s. When the ambient temperature T55 is less than the critical ambient temperature T55c, the circulating fan operates at its rated frequency, the waste heat condenser fan and condensate pump do not operate, the shut-off valve is closed, the drain valve is open, and the first three-way valve is adjusted to close the first branch and open the second branch. The compressor frequency, the air subcooler fan frequency, and the opening of the second three-way valve are adjusted until T56 stabilizes at the set value T56s. The control operation of the water-air combined subcooling mode (M4) is as follows: When the ambient temperature T55 is greater than the critical ambient temperature T55c, the circulating fan, waste heat condenser fan and air subcooler fan operate at the rated frequency, the condensate pump operates at the rated frequency, the shut-off valve is closed, the drain valve is closed, the first three-way valve is adjusted to open the first branch and close the second branch, and the compressor frequency and the opening of the second three-way valve are adjusted to stabilize at the set value T56s. When the ambient temperature T55 is less than the critical ambient temperature T55c, the circulating fan operates at the rated frequency, the waste heat condenser fan does not operate, the condensate pump operates at the rated frequency, the shut-off valve is closed, the drain valve is closed, the first three-way valve is adjusted to open the first branch and close the second branch, and the compressor frequency, the air subcooler fan frequency, and the opening of the second three-way valve are adjusted until T56 is stable to the set value T56s.

[0012] The beneficial effects of this invention are as follows: This invention provides a subcooled assisted sludge heat pump drying device. By connecting at least two parallel circuits through the high-pressure outlet of a refrigerant regenerator, one circuit is equipped with a subcooling component, and the other with an on / off control component. This achieves selective control of refrigerant subcooling, allowing flexible switching between subcooled and non-subcooled states based on the device's operating conditions, avoiding unnecessary energy loss. The subcooling component utilizes condensate and / or ambient air for refrigerant subcooling, fully leveraging the cooling capacity of condensate and ambient air generated during device operation. This solves the problem of direct condensate discharge and wasted cooling capacity in traditional devices, improving energy utilization. A control subsystem, controlling the subcooling mode of the subcooling component based on device operating parameters, enables intelligent regulation of the subcooling process, ensuring the subcooling mode always matches the device's operating conditions. This effectively mitigates the thermal imbalance problem of traditional devices, thereby improving energy efficiency. Furthermore, the coordinated operation of the refrigerant circuit subsystem, condensate circuit subsystem, air circuit subsystem, and control subsystem integrates refrigerant circulation, subcooling regulation, and cold source supply, enhancing the stability and reliability of the device's operation.

[0013] By setting up a control subsystem and regulating four operating modes—non-subcooling mode (M1), pure water subcooling mode (M2), pure air subcooling mode (M3), and water-air composite subcooling mode (M4)—precise adaptation of the control method to the device's operating conditions is achieved. This ensures that the air inlet temperature of the drying chamber remains stable at the set value T56s, guaranteeing the stability of the sludge drying effect. By setting four operating modes and clearly defined start-up conditions, combined with the first three-way valve and shut-off valve of the refrigerant loop subsystem, flexible switching of the subcooling mode is achieved. Based on parameters such as ambient temperature T55 and insulated water tank outlet temperature T52, the subcooling can be selectively performed using water subcoolers or air subcoolers, avoiding unnecessary energy loss and improving the overall energy efficiency and operational reliability of the device. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the system of the present invention; 1. Refrigerant circuit subsystem; 11. Compressor; 12. Main condenser; 13. Refrigerant regenerator; 14. Water subcooler; 15. Air subcooler; 16. Expansion valve; 17. Evaporator; 18. Waste heat condenser; 19. Shut-off valve; 2. Condensate circuit subsystem; 21. Drain tray; 22. Insulated water tank; 23. Condensate pump; 24. Drain valve; 25. Drain pipe; 3. Air circuit subsystem; 31. Circulating fan; 32. Drying chamber; 33. Air regenerator; 4. Control subsystem; 41. Controller; 51. First temperature sensor; 52. Second temperature sensor; 53. Third temperature sensor; 54. Fourth temperature sensor; 55. Fifth temperature sensor; 56. Sixth temperature sensor; 61. Air subcooler fan; 62. Waste heat condenser fan; 63. First three-way valve; 64. Second three-way valve. Detailed Implementation

[0015] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0016] like Figure 1 As shown, a subcooling-assisted sludge heat pump drying device includes: a refrigerant circuit subsystem 1, a condensate circuit subsystem 2, an air circuit subsystem 3, and a control subsystem 4. The refrigerant circuit subsystem 1 includes a compressor 11, a main condenser 12, a refrigerant regenerator 13, an expansion valve 16, and an evaporator 17. The high-pressure outlet of the refrigerant regenerator 13 is connected to at least two parallel circuits. One circuit is equipped with a subcooling component that uses condensate and / or ambient air to subcool the refrigerant, and the other circuit is equipped with an on / off control component. By switching the on / off state of the two circuits and the operating state of the subcooling component, the refrigerant at the outlet of the main condenser 12 is selectively subcooled. The control subsystem 4 is used to control the subcooling method of the refrigerant by the subcooling component according to the device operating parameters.

[0017] Specifically, the subcooled assisted sludge heat pump drying device consists of a refrigerant loop subsystem 1, a condensate loop subsystem 2, an air loop subsystem 3, and a control subsystem 4, forming a complete sludge heat pump drying system. The refrigerant loop subsystem 1 includes a compressor 11, a main condenser 12, a refrigerant regenerator 13, an expansion valve 16, and an evaporator 17. These components are interconnected to form a closed refrigerant circulation loop. The high-pressure outlet of the refrigerant regenerator 13 is connected to at least two parallel loops. One loop is equipped with a subcooling component for subcooling the refrigerant using condensate and / or ambient air, and the other loop is equipped with an on / off control component for controlling the on / off state of this loop. The control subsystem 4 is linked with the subcooling component and related components, receiving device operating parameters and outputting control signals. The condensate loop subsystem 2 and the air loop subsystem 3 work in conjunction with the refrigerant loop subsystem 1 to provide condensate and ambient air cold source support for the subcooling component. After the device starts up, the refrigerant circuit subsystem 1 begins operation. The compressor 11 compresses the refrigerant to a high-temperature, high-pressure state. After condensation and heat release by the main condenser 12, the refrigerant flows into the refrigerant regenerator 13 for heat recovery. Subsequently, it flows out from the high-pressure outlet of the refrigerant regenerator 13 and enters one of the two parallel circuits connected to it. The control subsystem 4 collects the device's operating parameters in real time and controls the operation mode of the subcooling component and the on / off status of the two parallel circuits based on parameter changes: When subcooling of the refrigerant is required, the control subsystem 4 controls the circuit where the on / off control component is located to close, allowing the refrigerant to flow through the subcooling component. The subcooling component selectively utilizes the condensate provided by the condensate circuit subsystem 2 and the low-temperature ambient air provided by the air circuit subsystem 3, or both, to subcool the refrigerant; when subcooling is not required, the control subsystem 4 controls the subcooling component to stop operating and simultaneously opens the circuit where the on / off control component is located, allowing the refrigerant to flow directly through this circuit to the expansion valve 16. After being processed, the refrigerant is throttled and depressurized by the expansion valve 16 and then enters the evaporator 17 to absorb heat and complete the refrigeration cycle, continuously providing energy support for the sludge drying process. Throughout the process, the control subsystem 4 is always dynamically adjusted according to the operating parameters to ensure that the subcooling mode matches the operating conditions of the device.In this application, by setting the high-pressure outlet of the refrigerant regenerator 13 to connect to at least two parallel circuits, with one circuit equipped with a subcooling component and the other with an on / off control component, selective control of refrigerant subcooling is achieved. This allows for flexible switching between subcooled and non-subcooled states based on the operating conditions of the device, avoiding unnecessary energy loss. The subcooling component utilizes condensate and / or ambient air to subcool the refrigerant, fully leveraging the cooling capacity of the condensate and ambient air generated during device operation. This solves the problem of direct condensate discharge and wasted cooling capacity in traditional devices, improving energy utilization. The control subsystem 4 controls the subcooling mode of the subcooling component based on the device's operating parameters, achieving intelligent regulation of the subcooling process. This ensures the subcooling mode is always compatible with the device's operating conditions, effectively mitigating the thermal imbalance problem of traditional devices and improving energy efficiency. The coordinated operation of the refrigerant circuit subsystem 1, condensate circuit subsystem 2, air circuit subsystem 3, and control subsystem 4 integrates refrigerant circulation, subcooling regulation, and cold source supply, enhancing the stability and reliability of the device operation.

[0018] like Figure 1 As shown, the subcooling assembly includes a water subcooler 14, an air subcooler 15, and a first three-way valve 63. The on / off control assembly is a shut-off valve 19. Of the two parallel circuits connected to the high-pressure outlet of the refrigerant regenerator 13, one circuit is divided into a first branch and a second branch via the first three-way valve 63. In the first branch, the high-pressure outlet of the refrigerant regenerator 13 is sequentially connected to the water subcooler 14 and the air subcooler 15. In the second branch, the high-pressure outlet of the refrigerant regenerator 13 is directly connected to the air subcooler 15. The other circuit is connected to the inlet of the expansion valve 16 via the shut-off valve 19. The outlet of the air subcooler 15 is connected to the inlet of the expansion valve 16.

[0019] Specifically, by controlling the two branches through the first three-way valve 63, the refrigerant can flexibly choose to flow through the series path of the water subcooler 14 and the air subcooler 15 or only through the air subcooler 15. This allows the system to switch between multiple modes, such as pure water subcooling, pure air subcooling, and combined subcooling, based on conditions such as condensate temperature and ambient temperature. At the same time, another parallel circuit equipped with a shut-off valve 19 provides a channel that completely bypasses the subcooling components, enabling the system to intelligently select the optimal subcooling mode or operate without subcooling based on actual operating conditions, ultimately achieving the optimal energy efficiency of the device.

[0020] like Figure 1As shown, the refrigerant circuit subsystem 1 further includes a waste heat condenser 18, a second three-way valve 64, an air subcooler 15 equipped with a variable frequency air subcooler fan 61, a waste heat condenser 18 equipped with a variable frequency waste heat condenser fan 62, and a compressor 11 that is a variable frequency compressor. The exhaust port of the compressor 11 is connected to the inlet of the second three-way valve 64, and the two outlets of the second three-way valve 64 are respectively connected to the refrigerant inlet of the main condenser 12 and the refrigerant inlet of the waste heat condenser 18. The refrigerant outlet of the main condenser 12 is connected to the high-pressure liquid inlet of the refrigerant regenerator 13, and the refrigerant outlet of the waste heat condenser 18 is connected to the high-pressure liquid inlet of the refrigerant regenerator 13. The outlet of the expansion valve 16 is connected to the refrigerant inlet of the evaporator 17, the refrigerant outlet of the evaporator 17 is connected to the low-pressure suction port of the refrigerant regenerator 13, and the low-pressure exhaust port of the refrigerant regenerator 13 is connected to the suction port of the compressor 11.

[0021] Specifically, the variable frequency compressor 11 can flexibly adjust its frequency according to the operating conditions of the device to adapt to the cooling needs of different modes. The second three-way valve 64 controls the refrigerant flow ratio of the compressor 11 exhaust to the main condenser 12 and the waste heat condenser 18 by different opening degrees. In conjunction with the waste heat condenser 18 equipped with the variable frequency waste heat condenser fan 62, the amount of waste heat discharged can be precisely controlled. The variable frequency air subcooler fan 61 equipped with the air subcooler 15 can adjust the air volume according to the subcooling needs to improve the subcooling efficiency.

[0022] like Figure 1 As shown, the condensate circuit subsystem 2 includes a water receiving tray 21, an insulated water tank 22, a condensate pump 23, a drain valve 24, and a water subcooler 14 shared with the refrigerant circuit subsystem 1. The water receiving tray 21 is located below the evaporator 17 and is connected to the insulated water tank 22 via a pipe. The insulated water tank 22 is connected in sequence to the condensate pump 23 and the water-side inlet of the water subcooler 14 via pipes. The bottom of the insulated water tank 22 is connected to the inlet of the drain valve 24 via a pipe. The outlet of the drain valve 24 is connected to the drain pipe 25. The water-side outlet of the water subcooler 14 is connected to the drain pipe 25.

[0023] Specifically, the evaporator condensate collected in the drip tray 21 is stored in the insulated water tank 22. When needed, the condensate pump 23 pumps it to the water subcooler 14 as a low-temperature cold source to subcool the refrigerant, making full use of the previously wasted condensate cooling capacity and improving energy efficiency. The insulated water tank 22 can reduce water temperature fluctuations and ensure stable subcooling effect, while the drain valve 24 and drain pipe 25 provide a channel for direct discharge of condensate when the temperature is too high or subcooling is not required, ensuring the controllability and reliability of system operation.

[0024] like Figure 1As shown, the air circuit subsystem 3 includes a circulating fan 31, a drying chamber 32, an air regenerator 33, and a main condenser 12 and an evaporator 17 shared with the refrigerant circuit subsystem 1. The outlet of the circulating fan 31 is connected to the air inlet of the drying chamber 32, the air outlet of the drying chamber 32 is connected to the hot air inlet of the air regenerator 33, the hot air outlet of the air regenerator 33 is connected to the air inlet of the evaporator 17, the air outlet of the evaporator 17 is connected to the cold air inlet of the air regenerator 33, the cold air outlet of the air regenerator 33 is connected to the air inlet of the main condenser 12, and the air outlet of the main condenser 12 is connected to the inlet of the circulating fan 31.

[0025] Specifically, the air loop subsystem 3 forms a closed-loop air circulation. After the hot dry air completes its dehumidification in the drying chamber 32, it flows through the air regenerator 33 to exchange heat with the low-temperature dry air from the evaporator 17, realizing the recovery of exhaust energy and reducing the dehumidification load of the evaporator 17 and the heating load of the main condenser 12. Subsequently, the air is cooled and dehumidified in the evaporator 17 and heated in the main condenser 12, and finally sent back to the drying chamber 32 by the circulating fan 31, improving the thermal efficiency of the drying process.

[0026] like Figure 1 As shown, the control subsystem 4 includes a controller 41, a first temperature sensor 51 located at the high-pressure outlet of the refrigerant regenerator 13, a second temperature sensor 52 located at the outlet of the insulated water tank 22, a third temperature sensor 53 located at the refrigerant outlet of the air subcooler 15, a fourth temperature sensor 54 located at the refrigerant outlet of the water subcooler 14, a fifth temperature sensor 55 for measuring ambient temperature, and a sixth temperature sensor 56 located at the air inlet of the drying chamber 32. Each temperature sensor is connected to the signal input terminal of the controller 41.

[0027] Specifically, the first temperature sensor 51 is located at the high-pressure outlet of the refrigerant regenerator 13, and the measured temperature is recorded as T51. The second temperature sensor 52 is located at the outlet of the insulated water tank 22, and the measured temperature is recorded as T52. The third temperature sensor 53 is located at the refrigerant outlet of the air subcooler 15, and the measured temperature is recorded as T53. The fourth temperature sensor 54 is located at the refrigerant outlet of the water subcooler 14, and the measured temperature is recorded as T54. The fifth sensor 55 is used to measure the ambient temperature, and the measured temperature is recorded as T55. The sixth temperature sensor 56 is located at the air inlet of the drying chamber 32, and the measured temperature is recorded as T56. The six temperature sensors used for measurement are connected to the signal input terminal of the controller 41. The first temperature sensor 51 monitors the temperature of the refrigerant before subcooling, the second temperature sensor 52 monitors the available condensate cold source temperature, the third temperature sensor 53 and the fourth temperature sensor 54 respectively provide feedback on the effects of air subcooling and water subcooling, the fifth temperature sensor 55 senses the ambient cold source conditions, and the sixth temperature sensor 56 detects the temperature of the drying hot air. The controller 41 collects temperature data in real time, forming a comprehensive monitoring closed loop. Based on accurate temperature information, the controller 41 can intelligently determine and switch the optimal subcooling operation mode, such as pure water subcooling, pure air subcooling, combined subcooling, or no subcooling. It also coordinates and adjusts the working status of the compressor 11, related fans, condensate pump 23, and various valves. Thus, while accurately controlling the inlet temperature of the drying chamber 32, the controller 41 enables the entire system to adapt to different operating conditions and achieve optimal energy efficiency.

[0028] like Figure 1 As shown, the signal output terminal of the controller 41 is connected to the compressor 11, the shut-off valve 19, the condensate pump 23, the circulating fan 31, the air subcooler fan 61, the waste heat condenser fan 62, the first three-way valve 63, and the second three-way valve 64, and is configured to control the start / stop, frequency, or opening degree of the components based on the measured values ​​of each temperature sensor.

[0029] Specifically, the controller 41 can perform comprehensive and coordinated closed-loop control of the frequency of the compressor 11, the start and stop of the condensate pump 23, the speed of the circulating fan 31, the frequency of the air subcooler fan 61 and the waste heat condenser fan 62, and the opening degree of the shut-off valve 19, the first three-way valve 63 and the second three-way valve 64 based on the real-time measurement values ​​of each temperature sensor. This achieves precise and automatic adjustment of key operating parameters such as refrigerant flow rate, condensation heat distribution, subcooling method and intensity, and air circulation status. The system can autonomously select and switch to the most energy-efficient operating mode according to real-time operating conditions (such as ambient temperature, condensate temperature, and drying requirement temperature). While ensuring a stable inlet temperature of the drying chamber 32, it dynamically optimizes the energy efficiency of the entire device, effectively mitigating the energy waste caused by the thermal imbalance of traditional devices.

[0030] like Figure 1 As shown, a control method for a subcooled assisted sludge heat pump drying device includes four operating modes: no subcooling mode (M1), pure water subcooling mode (M2), pure air subcooling mode (M3), and water-air composite subcooling mode (M4). The ambient temperature corresponding to the complete closure of the second three-way valve 64 on the waste heat condenser 18 side is defined as the critical ambient temperature T55c. The ambient temperature setpoint is set to T55s, and the air inlet temperature setpoint for the drying chamber 32 is set to T56s. The operating conditions for the four modes are as follows: It can operate in non-subcooling mode (M1) under any conditions; When the ambient temperature T55 is greater than 0℃ and the outlet water temperature T52 of the insulated water tank 22 is less than the high pressure outlet temperature T51 of the refrigerant regenerator 13, the pure water subcooling mode (M2) can be operated. When the ambient temperature T55 is less than the ambient temperature setpoint T55s, the pure air subcooling mode (M3) can be run. When the ambient temperature T55 is greater than 0℃, the outlet water temperature T52 of the insulated water tank 22 is less than the high-pressure outlet temperature T51 of the refrigerant regenerator 13, and the ambient temperature T55 is less than the refrigerant outlet temperature T54 of the water subcooler 14, the water-air composite subcooling mode (M4) can be operated; each mode stabilizes T56 to T56s by adjusting the relevant components.

[0031] Specifically, the control method includes four operating modes: no subcooling mode (M1), pure water subcooling mode (M2), pure air subcooling mode (M3), and water-air composite subcooling mode (M4). The ambient temperature when the second three-way valve 64 is completely closed on the waste heat condenser 18 side is defined as the critical ambient temperature T55c. The ambient temperature setpoint T55s and the air inlet temperature setpoint T56s of the drying chamber 32 are set. Each mode is activated according to the corresponding conditions, and all aim to stabilize T56 to T56s by adjusting the relevant components. The non-subcooling mode (M1) can be started under any conditions. In this mode, the control subsystem 4's regulating shut-off valve 19 is open, and the first three-way valve 63 is switched to the appropriate position. The refrigerant bypasses the water subcooler 14 and air subcooler 15 and directly enters the evaporator 17 through the expansion valve 16 to complete the circulation. The pure water subcooling mode (M2) is started when the ambient temperature T55 > 0℃ and the outlet water temperature of the insulated water tank 22 T52 < the high-pressure outlet temperature of the refrigerant regenerator 13 T51. In this mode, the control subsystem 4's regulating shut-off valve 19 is closed, and the first three-way valve 63 is switched to the corresponding branch. The refrigerant is subcooled by the condensate in the water subcooler 14 before entering the expansion valve 16. The pure air subcooling mode (M3) is started when T55 < T51. The system starts at 5 seconds. Control subsystem 4 controls the shut-off valve 19 to close and the first three-way valve 63 to switch to the corresponding branch. The refrigerant enters the expansion valve 16 after being subcooled by ambient air through the air subcooler 15. Water-air composite subcooling mode (M4) starts when T55 > 0℃, T52 < T51 and T55 < refrigerant outlet temperature T54 of water subcooler 14. Control subsystem 4 controls the shut-off valve 19 to close and the first three-way valve 63 to switch to the corresponding branch. The refrigerant enters the expansion valve 16 after being subcooled by both water subcooler 14 and air subcooler 15. Throughout the process, the compressor 11, valves and related components are controlled by control subsystem 4 to maintain the stable inlet temperature of drying chamber 32. By setting up a control subsystem 4 and regulating four operating modes—non-subcooling mode (M1), pure water subcooling mode (M2), pure air subcooling mode (M3), and water-air composite subcooling mode (M4)—precise adaptation of the control method to the device's operating conditions is achieved, ensuring that the air inlet temperature of the drying chamber 32 remains stable at the set value T56s, thus guaranteeing the stability of the sludge drying effect. By setting four operating modes and clear start-up conditions, combined with the first three-way valve 63 and the shut-off valve 19 of the refrigerant loop subsystem 1, flexible switching of the subcooling mode is achieved. Based on parameters such as the ambient temperature T55 and the outlet water temperature T52 of the insulated water tank 22, the subcooling can be selectively performed using the water subcooler 14 and the air subcooler 15, or not, avoiding unnecessary energy loss and improving the energy efficiency and operational reliability of the entire device.

[0032] like Figure 1As shown, the control operation of the non-subcooling mode (M1) is as follows: the compressor 11, the circulating fan 31 and the waste heat condenser fan 62 operate at the rated frequency, the air subcooler fan 61 does not operate, the condensate pump 23 does not operate, the shut-off valve 19 is opened, the drain valve 24 is opened, the first three-way valve 63 is adjusted so that both the first branch and the second branch are closed, and the opening degree of the second three-way valve 64 is adjusted until T56 is stable to the set value T56s; The control operation of the pure water subcooling mode (M2) is as follows: the circulating fan 31 and the waste heat condenser fan 62 operate at the rated frequency, the air subcooler fan 61 does not operate, the condensate pump 23 operates at the rated frequency, the shut-off valve 19 is closed, the drain valve 24 is closed, the first three-way valve 63 is adjusted to open the first branch and close the second branch, and the frequency of the compressor 11 and the opening degree of the second three-way valve 64 are adjusted until T56 is stable to the set value T56s; The control operation of the pure air subcooling mode (M3) is as follows: When the ambient temperature T55 is greater than the critical ambient temperature T55c, the circulating fan 31, the waste heat condenser fan 62 and the air subcooler fan 61 operate at the rated frequency, the condensate pump 23 does not operate, the shut-off valve 19 is closed, the drain valve 24 is opened, the first three-way valve 63 is adjusted to close the first branch and open the second branch, and the frequency of the compressor 11 and the opening of the second three-way valve 64 are adjusted until T56 is stable to the set value T56s. When the ambient temperature T55 is less than the critical ambient temperature T55c, the circulating fan 31 operates at its rated frequency, the waste heat condenser fan 62 and the condensate pump 23 do not operate, the shut-off valve 19 is closed, the drain valve 24 is opened, the first three-way valve 63 is adjusted to close the first branch and open the second branch, and the frequency of the compressor 11, the frequency of the air subcooler fan 61, and the opening of the second three-way valve 64 are adjusted until T56 stabilizes at the set value T56s. The control operation of the water-air combined subcooling mode (M4) is as follows: When the ambient temperature T55 is greater than the critical ambient temperature T55c, the circulating fan 31, the waste heat condenser fan 62 and the air subcooler fan 61 operate at the rated frequency, the condensate pump 23 operates at the rated frequency, the shut-off valve 19 is closed, the drain valve 24 is closed, the first three-way valve 63 is adjusted to open the first branch and close the second branch, and the frequency of the compressor 11 and the opening of the second three-way valve 64 are adjusted until T56 is stable to the set value T56s. When the ambient temperature T55 is less than the critical ambient temperature T55c, the circulating fan 31 operates at the rated frequency, the waste heat condenser fan 62 does not operate, the condensate pump 23 operates at the rated frequency, the shut-off valve 19 is closed, the drain valve 24 is closed, the first three-way valve 63 is adjusted to open the first branch and close the second branch, and the frequency of the compressor 11, the frequency of the air subcooler fan 61, and the opening degree of the second three-way valve 64 are adjusted until T56 is stable to the set value T56s.

[0033] Specifically, the activation of the four operating modes (M1-M4) is dynamically determined by conditions such as ambient temperature, condensate temperature, and refrigerant temperature. In terms of control execution, the first three-way valve 63 is adjusted in a coordinated manner to select the cooling path, the control shut-off valve 19 is used to open or close the bypass, the condensate pump 23 and the air subcooler fan 61 are started or stopped to activate the corresponding cold source, and the compressor 11 frequency and the opening degree of the second three-way valve 64 are adjusted to manage the total cooling / heating capacity and condensation heat distribution of the system, so as to accurately stabilize the drying chamber inlet temperature T56 at the set value T56s.

[0034] The subcooled assisted sludge heat pump drying device proposed in this application is not limited to sludge as a single material. Essentially, it is an intelligent heat pump system for efficient low-temperature drying of materials with high moisture content or similar drying characteristics. Its core lies in the flexible use of condensate and ambient air to subcool the refrigerant, thus solving the problems of thermal imbalance and energy waste in closed-loop heat pump drying processes. Therefore, this device and its control method are also applicable to a wide range of scenarios in food processing (drying fruits, vegetables, and seafood), chemical raw material dehydration, and industries such as textiles and papermaking where energy-saving drying of high-moisture materials is required.

[0035] The beneficial effects of this application compared with the prior art are as follows: This invention discloses a subcooling-assisted sludge heat pump drying device. After the device is started, the refrigerant circuit subsystem 1 begins operation. The compressor 11 compresses the refrigerant to a high-temperature, high-pressure state. After condensation and heat release by the main condenser 12, the refrigerant flows into the refrigerant regenerator 13 for heat recovery. Subsequently, it flows out from the high-pressure outlet of the refrigerant regenerator 13 and enters one of the two parallel circuits connected to it. The control subsystem 4 collects the device's operating parameters in real time and controls the operation mode of the subcooling component and the on / off state of the two parallel circuits according to the parameter changes: When subcooling of the refrigerant is required, the control subsystem 4 controls the circuit where the on / off control component is located to close, allowing the refrigerant to flow through the subcooling component. The subcooling component selectively utilizes the condensate provided by the condensate circuit subsystem 2 and the low-temperature ambient air provided by the air circuit subsystem 3, or both, to subcool the refrigerant; when subcooling is not required, the control subsystem 4 controls the subcooling component to stop operating and simultaneously opens the circuit where the on / off control component is located, allowing the refrigerant to flow directly through the circuit to the expansion valve 16. After being processed, the refrigerant is throttled and depressurized by the expansion valve 16 and then enters the evaporator 17 to absorb heat and complete the refrigeration cycle, continuously providing energy support for the sludge drying process. Throughout the process, the control subsystem 4 is always dynamically adjusted according to the operating parameters to ensure that the subcooling mode matches the operating conditions of the device. In this application, by setting the high-pressure outlet of the refrigerant regenerator 13 to connect to at least two parallel circuits, with one circuit equipped with a subcooling component and the other with an on / off control component, selective control of refrigerant subcooling is achieved. This allows for flexible switching between subcooled and non-subcooled states based on the operating conditions of the device, avoiding unnecessary energy loss. The subcooling component utilizes condensate and / or ambient air to subcool the refrigerant, fully leveraging the cooling capacity of the condensate and ambient air generated during device operation. This solves the problem of direct condensate discharge and wasted cooling capacity in traditional devices, improving energy utilization. The control subsystem 4 controls the subcooling mode of the subcooling component based on the device's operating parameters, achieving intelligent regulation of the subcooling process. This ensures the subcooling mode is always compatible with the device's operating conditions, effectively mitigating the thermal imbalance problem of traditional devices and improving energy efficiency. The coordinated operation of the refrigerant circuit subsystem 1, condensate circuit subsystem 2, air circuit subsystem 3, and control subsystem 4 integrates refrigerant circulation, subcooling regulation, and cold source supply, enhancing the stability and reliability of the device operation.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A subcooled assisted sludge heat pump drying device, comprising: The system comprises a refrigerant circuit subsystem (1), a condensate circuit subsystem (2), an air circuit subsystem (3), and a control subsystem (4). The refrigerant circuit subsystem (1) includes a compressor (11), a main condenser (12), a refrigerant regenerator (13), an expansion valve (16), and an evaporator (17). The high-pressure outlet of the refrigerant regenerator (13) is connected to at least two parallel circuits. One circuit is equipped with a subcooling component that uses condensate and / or ambient air to subcool the refrigerant, and the other circuit is equipped with an on / off control component. By switching the on / off state of the two circuits and the operating state of the subcooling component, the refrigerant at the outlet of the main condenser (12) is selectively subcooled. The control subsystem (4) is used to control the subcooling method of the refrigerant by the subcooling component according to the operating parameters of the device.

2. The subcooled assisted sludge heat pump drying device according to claim 1, characterized in that, The subcooling assembly includes a water subcooler (14), an air subcooler (15), and a first three-way valve (63). The on / off control assembly is a shut-off valve (19). Among the two parallel circuits connected to the high-pressure outlet of the refrigerant regenerator (13), one circuit is divided into a first branch and a second branch through the first three-way valve (63). In the first branch, the high-pressure outlet of the refrigerant regenerator (13) is connected to the water subcooler (14) and the air subcooler (15) in sequence. In the second branch, the high-pressure outlet of the refrigerant regenerator (13) is directly connected to the air subcooler (15). The other circuit is connected to the inlet of the expansion valve (16) through the shut-off valve (19). The outlet of the air subcooler (15) is connected to the inlet of the expansion valve (16).

3. The subcooled assisted sludge heat pump drying device according to claim 2, characterized in that, The refrigerant circuit subsystem (1) further includes a waste heat condenser (18) and a second three-way valve (64). The air subcooler (15) is equipped with a variable frequency air subcooler fan (61), and the waste heat condenser (18) is equipped with a variable frequency waste heat condenser fan (62). The compressor (11) is a variable frequency compressor. The exhaust port of the compressor (11) is connected to the inlet of the second three-way valve (64), and the two outlets of the second three-way valve (64) are respectively connected to the refrigerant inlet of the main condenser (12) and the waste heat condenser (18). 8) Refrigerant inlet connection: The refrigerant outlet of the main condenser (12) is connected to the high-pressure liquid inlet of the refrigerant regenerator (13); the refrigerant outlet of the waste heat condenser (18) is connected to the high-pressure liquid inlet of the refrigerant regenerator (13); the outlet of the expansion valve (16) is connected to the refrigerant inlet of the evaporator (17); the refrigerant outlet of the evaporator (17) is connected to the low-pressure suction port of the refrigerant regenerator (13); and the low-pressure exhaust port of the refrigerant regenerator (13) is connected to the suction port of the compressor (11).

4. The subcooled assisted sludge heat pump drying device according to claim 2, characterized in that, The condensate circuit subsystem (2) includes a water receiving pan (21), an insulated water tank (22), a condensate pump (23), a drain valve (24), and a water subcooler (14) shared with the refrigerant circuit subsystem (1). The water receiving pan (21) is located below the evaporator (17) and connected to the insulated water tank (22) via a pipe. The insulated water tank (22) is connected to the water-side inlet of the condensate pump (23) and the water subcooler (14) via pipes. The bottom of the insulated water tank (22) is connected to the inlet of the drain valve (24) via a pipe. The outlet of the drain valve (24) is connected to the drain pipe (25). The water-side outlet of the water subcooler (14) is connected to the drain pipe (25).

5. The subcooling-assisted sludge heat pump drying device according to claim 4, characterized in that, The air circuit subsystem (3) includes a circulating fan (31), a drying chamber (32), an air regenerator (33), and a main condenser (12) and an evaporator (17) shared with the refrigerant circuit subsystem (1). The outlet of the circulating fan (31) is connected to the air inlet of the drying chamber (32), the air outlet of the drying chamber (32) is connected to the hot air inlet of the air regenerator (33), the hot air outlet of the air regenerator (33) is connected to the air inlet of the evaporator (17), the air outlet of the evaporator (17) is connected to the cold air inlet of the air regenerator (33), the cold air outlet of the air regenerator (33) is connected to the air inlet of the main condenser (12), and the air outlet of the main condenser (12) is connected to the inlet of the circulating fan (31).

6. The subcooling-assisted sludge heat pump drying device according to claim 5, characterized in that, The control subsystem (4) includes a controller (41), a first temperature sensor (51) located at the high-pressure outlet of the refrigerant regenerator (13), a second temperature sensor (52) located at the outlet of the insulated water tank (22), a third temperature sensor (53) located at the refrigerant outlet of the air subcooler (15), a fourth temperature sensor (54) located at the refrigerant outlet of the water subcooler (14), a fifth temperature sensor (55) used to measure the ambient temperature, and a sixth temperature sensor (56) located at the air inlet of the drying chamber (32). Each temperature sensor is connected to the signal input terminal of the controller (41).

7. The subcooling-assisted sludge heat pump drying device according to claim 6, characterized in that, The signal output terminal of the controller (41) is connected to the compressor (11), the shut-off valve (19), the condensate pump (23), the circulating fan (31), the air subcooler fan (61), the waste heat condenser fan (62), the first three-way valve (63), and the second three-way valve (64), and is configured to control the start-up, shutdown, frequency, or opening degree of the components based on the measured values ​​of each temperature sensor.

8. A control method for a subcooled assisted sludge heat pump drying device, characterized in that, Including the subcooled assisted sludge heat pump drying device as described in any one of claims 1-7, the control method includes four operating modes: no subcooling mode (M1), pure water subcooling mode (M2), pure air subcooling mode (M3), and water-air composite subcooling mode (M4); the ambient temperature corresponding to when the second three-way valve (64) is completely closed on the waste heat condenser (18) side is defined as the critical ambient temperature T55c, the ambient temperature setpoint is set to T55s, and the air inlet temperature setpoint of the drying chamber (32) is set to T56s. The operating conditions of the four modes are as follows: It can operate in non-subcooling mode (M1) under any conditions; When the ambient temperature T55 is greater than 0℃ and the outlet water temperature T52 of the insulated water tank (22) is less than the high pressure outlet temperature T51 of the refrigerant regenerator (13), the pure water subcooling mode (M2) can be operated. When the ambient temperature T55 is less than the ambient temperature setpoint T55s, the pure air subcooling mode (M3) can be run. When the ambient temperature T55 is greater than 0℃, the outlet water temperature T52 of the insulated water tank (22) is less than the high pressure outlet temperature T51 of the refrigerant regenerator (13), and the ambient temperature T55 is less than the refrigerant outlet temperature T54 of the water subcooler (14), the water-air composite subcooling mode (M4) can be operated; each mode stabilizes T56 to T56s by adjusting the relevant components.

9. The control method according to claim 8, characterized in that, The control operation of the non-subcooling mode (M1) is as follows: the compressor (11), the circulating fan (31) and the waste heat condenser fan (62) operate at the rated frequency, the air subcooler fan (61) does not operate, the condensate pump (23) does not operate, the shut-off valve (19) is opened, the drain valve (24) is opened, the first three-way valve (63) is adjusted so that the first branch and the second branch are both closed, and the opening degree of the second three-way valve (64) is adjusted to stabilize at the set value T56s. The control operation of the pure water subcooling mode (M2) is as follows: the circulating fan (31) and the waste heat condenser fan (62) operate at the rated frequency, the air subcooler fan (61) does not operate, the condensate pump (23) operates at the rated frequency, the shut-off valve (19) is closed, the drain valve (24) is closed, the first three-way valve (63) is adjusted to open the first branch and close the second branch, and the compressor (11) frequency and the opening degree of the second three-way valve (64) are adjusted to stabilize at the set value T56s. The control operation of the pure air subcooling mode (M3) is as follows: When the ambient temperature T55 is greater than the critical ambient temperature T55c, the circulating fan (31), the waste heat condenser fan (62) and the air subcooler fan (61) operate at the rated frequency, the condensate pump (23) does not operate, the shut-off valve (19) is closed, the drain valve (24) is opened, the first three-way valve (63) is adjusted to close the first branch and open the second branch, and the compressor (11) frequency and the opening of the second three-way valve (64) are adjusted until T56 is stable to the set value T56s; When the ambient temperature T55 is less than the critical ambient temperature T55c, the circulating fan (31) operates at the rated frequency, the waste heat condenser fan (62) and condensate pump (23) do not operate, the shut-off valve (19) is closed, the drain valve (24) is opened, the first three-way valve (63) is adjusted to close the first branch and open the second branch, and the compressor (11) frequency, the air subcooler fan (61) frequency and the opening degree of the second three-way valve (64) are adjusted until T56 is stable to the set value T56s; The control operation of the water-air combined subcooling mode (M4) is as follows: When the ambient temperature T55 is greater than the critical ambient temperature T55c, the circulating fan (31), the waste heat condenser fan (62) and the air subcooler fan (61) operate at the rated frequency, the condensate pump (23) operates at the rated frequency, the shut-off valve (19) is closed, the drain valve (24) is closed, the first three-way valve (63) is adjusted to open the first branch and close the second branch, and the frequency of the compressor (11) and the opening degree of the second three-way valve (64) are adjusted until T56 is stable to the set value T56s; When the ambient temperature T55 is less than the critical ambient temperature T55c, the circulating fan (31) operates at the rated frequency, the waste heat condenser fan (62) does not operate, the condensate pump (23) operates at the rated frequency, the shut-off valve (19) is closed, the drain valve (24) is closed, the first three-way valve (63) is adjusted to open the first branch and close the second branch, and the compressor (11) frequency, the air subcooler fan (61) frequency and the opening degree of the second three-way valve (64) are adjusted until T56 is stable to the set value T56s.

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