An ultra-high temperature hot water device and its intelligent control method

Abstract

This invention discloses an ultra-high temperature hot water device and its intelligent control method. It mainly solves the problems of existing heat pump water heaters providing low-temperature hot water (80-130℃) and being unsuitable for use in environments below -10℃ and above 38℃. Its features include: a plate condenser evaporator (4) is provided between the low-temperature stage heating system (1) and the high-temperature stage heating system (2), one side of which is connected to the low-temperature stage heating system (1); and employs ① start-up control, ② frequency conversion control of the low-temperature stage compressor (101), ③ expansion valve control of the main circuits of the low-temperature and high-temperature stages, ④ expansion valve control of the auxiliary circuits of the low-temperature and high-temperature stages, and ⑤ defrosting control. This invention combines a low-temperature stage heating system and a high-temperature stage heating system, enabling the production of high-temperature hot water (80-130℃), and allowing use in environments below -10℃ and above 38℃.

Description

Technical Field

[0001] This invention relates to a commercial and industrial hot water production device, specifically to an ultra-high temperature hot water device and its intelligent control method. Background Technology

[0002] A heat pump water heater is a device that transfers heat from a low-temperature heat source (such as air, soil, seawater, groundwater, etc.) to water that needs heating, thereby heating the water. Existing heat pump water heaters provide hot water in the range of 40–55℃, but cannot provide high-temperature hot water of 80–130℃. The ambient temperature range is 0–43℃ or -7–38℃. The compressor uses a fixed-frequency or variable-frequency compressor, operating on a single-stage compression refrigeration cycle. At low ambient temperatures, the heating capacity decreases significantly, resulting in low energy efficiency. It is not suitable for environments below -10℃ or above 38℃. Traditional defrosting methods include: ① Four-way valve reverse circulation defrosting, where the defrosting heat comes from the hot water on the user side, causing a drop in water temperature during defrosting. ② Electric defrosting, utilizing high-grade electricity, is not energy-efficient and has poor economic performance. ③ Hot gas bypass defrosting, using the compressor's heat energy for defrosting, results in very low compressor exhaust temperatures, preventing prolonged defrosting and causing incomplete defrosting. Existing heat pump water heaters use traditional control technology, resulting in relatively simple control systems. Based on the aforementioned existing technology, these heat pump water heaters cannot meet the needs of some locations requiring high-temperature hot water (such as electroplating plants, slaughterhouses, chemical plants, and dairy farms that require high-temperature hot water or steam). Summary of the Invention

[0003] To address the issues of existing heat pump water heaters providing low-temperature hot water (80-130℃) and being unsuitable for use in environments below -10℃ and above 38℃, this invention provides an ultra-high temperature hot water device and its intelligent control method. This device combines a low-temperature heating system with a high-temperature heating system, enabling the production of high-temperature hot water (80-130℃) and allowing for use in environments below -10℃ and above 38℃.

[0004] The technical solution of this invention is: an ultra-high temperature hot water device, comprising a low-temperature stage heating system, a high-temperature stage heating system, a heat storage system, and a control system. A plate condenser-evaporator is provided between the low-temperature stage heating system and the high-temperature stage heating system. One side of the plate condenser-evaporator is connected to the low-temperature stage heating system, and the other side is connected to the high-temperature stage heating system. The low-temperature stage heating system absorbs heat from an external low-temperature heat source, and the high-temperature stage heating system absorbs heat from the plate condenser-evaporator. The heat storage system includes a low-temperature stage storage tank and a high-temperature stage storage tank, which are connected in series by a pipeline. A water pump and a defrosting water temperature sensor are provided in the pipeline. The low-temperature stage storage tank is connected to the low-temperature stage heating system through a low-temperature stage inlet solenoid valve and a low-temperature stage outlet solenoid valve. The high-temperature stage storage tank is connected to the high-temperature stage heating system through a high-temperature stage inlet solenoid valve and a high-temperature stage outlet solenoid valve. A defrosting bypass valve is provided between the heat storage system and the low-temperature stage heating system.

[0005] The low-temperature heating system includes a low-temperature compressor, an oil separator, a plate condenser evaporator, a low-temperature liquid receiver, a low-temperature economizer, a low-temperature main electronic expansion valve, a low-temperature auxiliary electronic expansion valve, an evaporator, an evaporator fan, a gas-liquid separator, a temperature sensor, a pressure sensor, and a pressure switch. The low-temperature auxiliary electronic expansion valve is connected to the low-temperature economizer, and the outlet pipe of the low-temperature compressor is connected to the low-temperature pipe of the plate condenser evaporator.

[0006] The low-temperature stage compressor is a variable frequency scroll compressor, and the evaporator is a V-shaped combined finned evaporator.

[0007] The high-temperature heating system includes a high-temperature compressor, a plate condenser, a plate condenser-evaporator, a high-temperature gas-liquid separator, a high-temperature economizer, a high-temperature liquid receiver, a high-temperature main circuit electronic expansion valve, and a high-temperature auxiliary circuit electronic expansion valve. The high-temperature auxiliary circuit electronic expansion valve is connected to the high-temperature economizer, and the inlet pipe of the high-temperature compressor is connected to the high-temperature pipe of the plate condenser-evaporator.

[0008] The high-temperature stage compressor is a scroll compressor with high condensing temperature and high evaporating temperature.

[0009] The control system adopts Siemens SMART200 series PLC and Kunlun Tongtai HMI human-machine interface. The control system can realize the control of low temperature stage compressor, high temperature stage compressor, low temperature stage main circuit expansion valve, low temperature stage auxiliary circuit expansion valve, high temperature stage main circuit expansion valve, high temperature stage auxiliary circuit expansion valve, evaporator fan control and fault handling control.

[0010] The intelligent control method for the above-mentioned ultra-high temperature hot water device includes the following steps:

[0011] ① Start-up control: First, start the evaporator fan. Determine the starting order of the high-temperature stage compressor and the low-temperature stage compressor based on the high-temperature stage evaporation temperature. When the detected high-temperature stage evaporation temperature is ≥15℃, start the high-temperature stage compressor first, and then start the low-temperature stage compressor 5 seconds later. When the detected high-temperature stage evaporation temperature is <15℃, start the low-temperature stage compressor first, and then start the high-temperature stage compressor after the detected high-temperature stage evaporation temperature is ≥20℃.

[0012] ② The low-temperature stage compressor is controlled by frequency converter. The initial speed of the low-temperature stage compressor is 2400 rpm, and it maintains this speed for 3 minutes before switching to automatic adjustment mode to ensure that the low-temperature stage compressor and the high-temperature stage compressor operate within their respective allowable operating ranges.

[0013] ③ Low-temperature stage and high-temperature stage main circuit expansion valve control: After the evaporator fan starts, before the low-temperature stage compressor and high-temperature stage compressor start, the low-temperature stage main circuit electronic expansion valve and the high-temperature stage main circuit electronic expansion valve are opened in advance at 30% opening degree. After the low-temperature stage compressor and the high-temperature stage compressor start, the evaporation pressure and suction temperature of the main circuit are detected and converted into evaporation temperature. The superheat is calculated and compared with the preset superheat. The opening degree of the low-temperature stage main circuit electronic expansion valve and the high-temperature stage main circuit electronic expansion valve is automatically adjusted according to the superheat difference.

[0014] ④ Low-temperature stage and high-temperature stage auxiliary circuit expansion valve control: When the low-temperature stage compressor and the high-temperature stage compressor start, the evaporation pressure is converted into evaporation temperature by detecting the evaporation pressure and suction temperature of the auxiliary circuit, the superheat is calculated, and compared with the preset superheat. The opening degree of the low-temperature stage auxiliary circuit electronic expansion valve and the high-temperature stage auxiliary circuit electronic expansion valve is automatically adjusted according to the superheat difference.

[0015] ⑤ Defrosting control: The following conditions must be met simultaneously to initiate defrosting:

[0016] (1) The running time of both the low-temperature stage compressor and the high-temperature stage compressor is ≥7 minutes;

[0017] (2) The difference between the ambient temperature and the evaporator fin temperature in the low-temperature heating system is ≥10℃;

[0018] (3) Ambient temperature ≤ 5℃;

[0019] (4) The evaporator fin temperature in the low-temperature heating system is ≤-2℃;

[0020] (5) The defrosting interval is ≥45 minutes. When the evaporator fin temperature in the low-temperature heating system is ≤0℃, the defrosting interval starts to be counted. If the evaporator fin temperature is ≥2℃ for 3 minutes during the counting process, the defrosting time is reset to zero.

[0021] Defrosting will end if any of the following conditions are met:

[0022] (1) The evaporator fin temperature in the low-temperature heating system is ≥15℃;

[0023] (2) Defrosting time ≥ 10 minutes;

[0024] (3) High-pressure protection for the cryogenic compressor;

[0025] (4) The temperature of the cryogenic stage liquid receiver is below 10℃.

[0026] The maximum total air volume of the evaporator fan is 100%. Two fans are used to combine the air volume from 10% to 100%. One fan is a fixed-speed fan with an air volume of 50%, and the other fan is an EC speed-regulating fan with an air volume of 10-50%. The air volume adjustment range is large to meet the stable operation under different working conditions. When the unit receives the start command, the EC speed-regulating fan is turned on first with an initial speed of 30%. After the unit compressor starts, it enters the automatic fan adjustment mode.

[0027] When the evaporator fan is automatically adjusted, the unit adjusts according to the comparison between the set value of the low-temperature stage evaporation pressure and the actual evaporation pressure. It adopts PID control mode with a PID output range of 10-100%. When the evaporation pressure is greater than the set value, the air volume is reduced; when the evaporation pressure is less than the set value, the air volume is increased. The low-temperature stage evaporation pressure is always kept within the range of 8.0 Bar ± 0.1.

[0028] The present invention has the following beneficial effects: Due to the adoption of the above technical solution, the main function of the low-temperature stage heating system is to absorb heat from the air and transfer it to the high-temperature stage heating system through a plate condenser evaporator. This ensures that the high-temperature stage heating system operates at a higher evaporation temperature, allowing the plate condenser in the high-temperature stage heating system to reach an even higher temperature. High-temperature hot water is obtained after heat exchange through the plate condenser, achieving the goal of providing high-temperature hot water at 80–130°C. The present invention can provide high-temperature hot water at 80–130°C and can be used in environments below -10°C and above 38°C. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the working principle of the present invention.

[0030] Figure 2 This is a schematic diagram of the working principle of the low-temperature stage heating system 1 in this invention.

[0031] Figure 3 This is a schematic diagram of the working principle of the high-temperature heating system 2 in this invention.

[0032] Figure 4 This is a schematic diagram of the working principle of the thermal storage system 3 in this invention.

[0033] Figure 5 This is the control flowchart of the present invention.

[0034] In the diagram: 1-Low-temperature heating system, 101-Low-temperature compressor, 102-Oil separator, 103-Low-temperature liquid receiver, 104-Low-temperature economizer, 105-Low-temperature main circuit electronic expansion valve, 106-Low-temperature auxiliary circuit electronic expansion valve, 107-Evaporator, 108-Evaporator fan, 109-Gas-liquid separator, 110-Temperature sensor, 111-Pressure sensor, 112-Pressure switch, 2-High-temperature heating system, 201-High-temperature compressor, 202-Plate condenser, 203- 204-High-temperature gas-liquid separator, 205-High-temperature liquid storage tank, 206-High-temperature main circuit electronic expansion valve, 207-High-temperature auxiliary circuit electronic expansion valve, 3-Heat storage system, 31-Low-temperature liquid storage tank, 32-High-temperature liquid storage tank, 33-Pipeline, 34-Water pump, 35-Defrosting water temperature sensor, 36-Low-temperature inlet solenoid valve, 37-Low-temperature outlet solenoid valve, 38-High-temperature inlet solenoid valve, 39-High-temperature outlet solenoid valve, 4-Plate condenser-evaporator, 5-Defrosting bypass valve. Implementation

[0035] The present invention will now be described clearly and completely with reference to the accompanying drawings.

[0036] like Figures 1-5As shown, an ultra-high temperature hot water device includes a low-temperature stage heating system 1, a high-temperature stage heating system 2, a heat storage system 3, and a control system. A plate condenser evaporator 4 is provided between the low-temperature stage heating system 1 and the high-temperature stage heating system 2. One side of the plate condenser evaporator 4 is connected to the low-temperature stage heating system 1, and the other side is connected to the high-temperature stage heating system 2. The low-temperature stage heating system 1 absorbs heat from an external low-temperature heat source, and the high-temperature stage heating system 2 absorbs heat from the plate condenser evaporator 4. The heat storage system 3 includes... The system includes a low-temperature storage tank 31 and a high-temperature storage tank 32. The low-temperature storage tank 31 and the high-temperature storage tank 32 are connected in series by a pipeline 33. The pipeline 33 is equipped with a water pump 34 and a defrosting water temperature sensor 35. The low-temperature storage tank 31 is connected to the low-temperature heating system 1 through a low-temperature inlet solenoid valve 36 and a low-temperature outlet solenoid valve 37. The high-temperature storage tank 32 is connected to the high-temperature heating system 2 through a high-temperature inlet solenoid valve 38 and a high-temperature outlet solenoid valve 39. A defrosting bypass valve 5 is provided between the heat storage system 3 and the low-temperature heating system 1. Due to the adoption of the above technical solution, the main function of the low-temperature heating system 1 is to absorb heat from the air and transfer it to the high-temperature heating system 2 through the plate condenser evaporator 4. This ensures that the high-temperature heating system 2 operates at a higher evaporation temperature, allowing the plate condenser 202 in the high-temperature heating system 2 to reach an even higher temperature. After heat exchange through the plate condenser 202, high-temperature hot water is obtained, achieving the purpose of providing high-temperature hot water at 80-130℃. The heat storage system 3 is an auxiliary system used to store the heat for defrosting, ensuring the normal operation of the unit and preventing malfunctions due to excessive frost buildup. When the ambient temperature and the defrost temperature sensor reach the defrost timing requirements, the high-temperature stage inlet solenoid valve 38 and the high-temperature stage outlet solenoid valve 39 open, and the defrost water pump 34 starts. The high-temperature stage liquid refrigerant flows through the high-temperature stage storage tank 32, heating the water, which is then pumped by the pump 34 to the low-temperature stage storage tank 31. This process is repeated multiple times, gradually heating the water in the heat storage system 3 to the predetermined temperature for use during defrosting. When the water temperature in the heat storage system 3 reaches approximately 70°C, the high-temperature stage inlet solenoid valve 38 and the high-temperature stage outlet solenoid valve 39 close, and the heat storage system 3 stops operating. When the defrost conditions are met, the high-temperature stage outlet solenoid valve 39 opens, and the defrost water pump 34 starts operating. The water in the pipeline 33 flows between the low-temperature stage storage tank 31 and the high-temperature stage storage tank 32, gradually heating the water used for defrosting. During defrosting, three solenoid valves—the low-temperature stage inlet solenoid valve 36, the low-temperature stage outlet solenoid valve 37, and the defrost bypass valve 5—open, allowing warmer refrigerant liquid to enter the evaporator 107 and initiating defrosting. This invention can provide high-temperature hot water at 80–130°C and can be used in environments below -10°C and above 38°C.

[0037] The low-temperature stage heating system 1 includes a low-temperature stage compressor 101, an oil separator 102, a plate condenser-evaporator 4, a low-temperature stage liquid receiver 103, a low-temperature stage economizer 104, a low-temperature stage main circuit electronic expansion valve 105, a low-temperature stage auxiliary circuit electronic expansion valve 106, an evaporator 107, an evaporator fan 108, a gas-liquid separator 109, a temperature sensor 110, a pressure sensor 111, and a pressure switch 112. The low-temperature stage auxiliary circuit electronic expansion valve 106 is connected to the low-temperature stage economizer 104, and the outlet pipe of the low-temperature stage compressor 101 is connected to the low-temperature stage pipe of the plate condenser-evaporator 4. By using the low-temperature stage economizer 104 to circulate and reduce the exhaust temperature of the low-temperature stage compressor 101, the circulation efficiency of the low-temperature stage heating system 1 can be effectively improved, and the application range of the low-temperature stage compressor 101 can be expanded.

[0038] The low-temperature stage compressor 101 is a variable frequency scroll compressor, and the evaporator 107 is a V-shaped combined fin evaporator. The low-temperature stage compressor 101 in the low-temperature stage heating system 1 uses a variable frequency scroll compressor, which has a wide evaporation temperature range (-35℃ to 15℃), making the heating capacity of the low-temperature stage heating system 1 adjustable. It can provide sufficient heating capacity under low-temperature conditions, enabling the low-temperature stage heating system 1 to operate normally between ambient temperatures of -25℃ and 45℃. The evaporator 107 uses a V-shaped combined fin evaporator, which can fully absorb heat from the air. The evaporator fan 108 uses two axial flow fans. In summer, excessively high evaporation pressure may occur; this can be regulated by stopping one of the axial flow fans.

[0039] The high-temperature stage heating system 2 includes a high-temperature stage compressor 201, a plate condenser 202, a plate condenser-evaporator 4, a high-temperature stage gas-liquid separator 203, a high-temperature stage economizer 204, a high-temperature stage liquid receiver 205, a high-temperature stage main circuit electronic expansion valve 206, and a high-temperature stage auxiliary circuit electronic expansion valve 207. The high-temperature stage auxiliary circuit electronic expansion valve 207 is connected to the high-temperature stage economizer 204. The inlet pipe of the high-temperature stage compressor 201 is connected to the high-temperature stage pipe of the plate condenser-evaporator 4. The high-temperature stage heating system 2 regulates the condensation temperature by adjusting the water flow rate through the plate condenser 202, thereby controlling the water temperature. A higher water flow rate results in a lower outlet water temperature, while a lower water flow rate results in a higher outlet water temperature. By adjusting the water flow rate, the outlet water temperature can be varied between 70 and 130°C.

[0040] The high-temperature stage compressor 201 is a scroll compressor with high condensing and high evaporating temperatures. The low-temperature stage compressor 101 has a condensing temperature range of 15℃ to 55℃, and the high-temperature stage compressor 201 has a condensing temperature range of 22℃ to 55℃, allowing the low-temperature stage compressor 101 and the high-temperature stage compressor 201 to be used in combination.

[0041] The control system employs a Siemens SMART200 series PLC and a Kunlun Tongtai HMI (Human Machine Interface). It can control the cryogenic compressor, high-temperature compressor, cryogenic main expansion valve, cryogenic auxiliary expansion valve, high-temperature main expansion valve, high-temperature auxiliary expansion valve, evaporator fan, and handle faults. The control system is modular: one main unit supports seven sub-units. Only the main unit is equipped with a touchscreen. All sub-unit parameters are set by the main unit. Any unit can be either a main unit or a sub-unit; simply designate one unit as the main unit on the touchscreen and configure the communication addresses for the remaining units. It uses MODBUS RTU communication. Data collected by each unit is stored in the CPU's internal data storage area, awaiting retrieval by the main unit. The main unit program is configured with polling read / write instructions to read and write data from all sub-units within a specified period. The unit communication address is set via pulse input, eliminating the need for a touchscreen and requiring no specific installation order. Through physical input signals, each press of the signal generator cycles the unit address from 0 to 7. The current address is determined by observing the status of three output points. After setting the address, the CPU is powered on and off twice within 10 seconds to complete the setting. The control system's loading and unloading process compares the set temperature with the outlet water temperature, calculating the required number of operating units using an energy level algorithm. The deviation value is calculated as: Target Temperature - Total Outlet Water Temperature = Deviation Value. The energy level loading and unloading deviation range is set to 1-5℃, with a temperature change rate of 1℃ and a temperature change time of 3 minutes. Up to 8 units can be put into operation. This number is set based on the actual configuration. When units in the system are faulty, offline, or not activated and therefore unusable, the system will automatically calculate the number of operational units based on the unit status. The results show that the loading requirement is 1 unit when the deviation is ≥1℃, 3 units when the deviation is ≥2℃, 5 units when the deviation is ≥3℃, 6 ​​units when the deviation is ≥4℃, and 8 units when the deviation is ≥5℃. This loading requirement varies depending on the energy level loading / unloading deviation range and the actual number of units available. For example, if the system performs one loading cycle and the total outlet water temperature rises by no more than 1℃ within 3 minutes based on the temperature change rate and time, an additional unit will be loaded; the reverse applies during unloading. The energy level loading / unloading logic program distributes start / stop commands to the sub-units, with all sub-units receiving unified start / stop instructions from the host. Before loading / unloading, the operating time of each unit is compared. During loading, units with shorter operating times and no faults are prioritized for startup; during unloading, units with longer operating times are prioritized for shutdown, ensuring a balanced operating time for all units. The host can configure whether sub-units in the network are in use; if not, loading will automatically bypass that sub-unit. Communication between the host and slave units: A polling read / write method is used. When any one or more units in the network are offline or experience a fatal failure, it will not affect the normal communication of other units in the network, ensuring the stable operation of the system.A communication lifecycle tracking program is established between the master and slave units. The master sends instructions to the slave unit within each time period. Upon receiving the instruction, the slave unit needs to respond to the master. If the master does not receive a response from the slave within the period, it determines that the slave unit is offline and sets it to unavailable. Similarly, if the slave unit also does not receive an instruction from the master within the period, it considers the master unit offline. If the slave unit is running at this time, it will automatically shut down the unit.

[0042] The intelligent control method for the above-mentioned ultra-high temperature hot water device includes the following steps:

[0043] ① Start-up control: First, start the evaporator fan 108. Determine the starting order of the high-temperature stage compressor 201 and the low-temperature stage compressor 101 based on the high-temperature stage evaporation temperature. When the detected high-temperature stage evaporation temperature is ≥15℃, start the high-temperature stage compressor 201 first, and then start the low-temperature stage compressor 101 after 5 seconds to avoid starting the low-temperature stage compressor 101 first and then starting the high-temperature stage compressor 201 under pressure. When the detected high-temperature stage evaporation temperature is <15℃, start the low-temperature stage compressor 101 first, and then start the high-temperature stage compressor 201 after the detected high-temperature stage evaporation temperature is ≥20℃ to prevent the high-temperature stage compressor 201 from operating under unacceptable conditions when starting in low ambient temperature conditions, thus ensuring system stability.

[0044] ② The low-temperature stage compressor 101 is controlled by frequency converter. The initial speed of the low-temperature stage compressor 101 is 2400 rpm, and it maintains this speed for 3 minutes before switching to automatic adjustment mode to ensure that the low-temperature stage compressor 101 and the high-temperature stage compressor 201 operate within their respective allowable operating ranges. The refrigerant circuits of the low-temperature stage heating system 1 and the high-temperature stage heating system 2 adopt the cascade principle. The heat source in the high-temperature stage heating system 2 comes from the plate condenser evaporator 4. The speed adopts a time-cycle fuzzy control mode. When the high-temperature stage evaporation pressure is ≤ 15℃ - 2℃, the compressor speed increases at a rate of 60 rpm every 10 seconds. When the evaporation pressure is ≥ 15℃ + 2℃, the speed decreases at a rate of 60 rpm every 10 seconds. When the evaporation pressure is < 15℃ + 2℃ and > 15℃ - 2℃, the current speed remains unchanged. When the evaporating pressure is ≤ 15℃ - 2℃ within the set range - 2℃ beyond the set range, the compressor speed increases at a rate of 120 rpm every 10 seconds. When the evaporating pressure is ≥ 15℃ + 2℃ within the set range + 2℃ beyond the set range, the compressor speed decreases at a rate of 120 rpm every 10 seconds. Compressor speed limits are set to ensure optimal operation under specific conditions. Specifically, maximum and minimum speeds are limited. When the ambient temperature is ≥ 10℃, the minimum speed is 1800 rpm and the maximum speed is 6000 rpm; when the ambient temperature is ≥ -10℃ and < 10℃, the minimum speed is 2100 rpm and the maximum speed is 6600 rpm; when the ambient temperature is ≥ -25℃ and < -10℃, the minimum speed is 2400 rpm and the maximum speed is 7200 rpm; when the ambient temperature is < -25℃, the minimum speed is 3000 rpm and the maximum speed is 7800 rpm. Compressor Inverter Temperature Protection: To ensure stable inverter operation, the following restrictions are implemented: When the module temperature ≥ 85℃, the speed is not allowed to increase, but can be decreased; this restriction is lifted when the temperature is < 82℃. When the module temperature ≥ 90℃, the speed decreases at a rate of 60 revolutions per 60 seconds; this restriction is lifted when the temperature is < 87℃. When the module temperature ≥ 95℃, the unit is forced to shut down the compressor; this restriction is lifted when the temperature is < 90℃. Oil Return Speed ​​Limitation: To avoid prolonged operation of the compressor speed within extreme ranges, which may affect the oil return effect, the following restrictions are implemented: When the compressor speed ≥ 5400 rpm and the operating time ≥ 45 minutes, it is forced to operate at 3000 rpm for 3 minutes; when the compressor speed ≤ 2400 rpm and the operating time ≥ 45 minutes, it is forced to operate at 3000 rpm for 3 minutes.

[0045] ③ Low-temperature and high-temperature stage main circuit expansion valve control: After the evaporator fan 108 starts, before the low-temperature stage compressor 101 and the high-temperature stage compressor 201 start, the low-temperature stage main circuit electronic expansion valve 105 and the high-temperature stage main circuit electronic expansion valve 206 are both opened at 30% opening degree in advance. After the low-temperature stage compressor 101 and the high-temperature stage compressor 201 start, the evaporation pressure and suction temperature of the main circuit are detected and converted into evaporation temperature. The superheat is calculated and compared with the preset superheat. The opening degree of the low-temperature stage main circuit electronic expansion valve 105 and the high-temperature stage main circuit electronic expansion valve 206 is automatically adjusted according to the superheat difference. The superheat is calculated as: superheat = suction temperature - evaporation temperature. The superheat is automatically adjusted according to the preset superheat. When the detected superheat is greater than the "set superheat", the PID control command calculates the output ratio based on the superheat difference, loop gain P value, and integral time I value. The larger the difference, the faster the expansion valve opens. When the detected superheat is less than the "set superheat", the opening steps are reversed. When the difference is closer, the PID output ratio weakens, and the expansion valve opens more slowly until the difference is 0, at which point the expansion valve maintains its current opening.

[0046] ④ Low-temperature stage and high-temperature stage auxiliary expansion valve control: When the low-temperature stage compressor 101 and the high-temperature stage compressor 201 are started, the evaporation pressure and suction temperature of the auxiliary circuit are detected and converted into evaporation temperature. The superheat is calculated and compared with the preset superheat. The opening degree of the low-temperature stage auxiliary circuit electronic expansion valve 106 and the high-temperature stage auxiliary circuit electronic expansion valve 207 is automatically adjusted according to the superheat difference. The superheat calculation and automatic adjustment process is the same as the main circuit expansion valve control method.

[0047] ⑤ Defrosting control: The following conditions must be met simultaneously to initiate defrosting:

[0048] (1) The running time of both the low-temperature stage compressor 101 and the high-temperature stage compressor 201 is ≥7 minutes;

[0049] (2) The difference between the ambient temperature and the fin temperature of the evaporator 107 in the low-temperature heating system 1 is ≥10℃;

[0050] (3) Ambient temperature ≤ 5℃;

[0051] (4) The fin temperature of the evaporator 107 in the low-temperature heating system 1 is ≤-2℃;

[0052] (5) When the defrosting interval is ≥45 minutes and the temperature of the evaporator 107 fin in the low-temperature heating system 1 is ≤0℃, the defrosting interval starts to be counted. If the temperature of the evaporator 107 fin is ≥2℃ for 3 minutes during the counting process, the defrosting time is reset to zero.

[0053] Defrosting will end if any of the following conditions are met:

[0054] (1) The fin temperature of the evaporator 107 in the low-temperature heating system 1 is ≥15℃;

[0055] (2) Defrosting time ≥ 10 minutes;

[0056] (3) High-pressure protection of the cryogenic compressor 101;

[0057] (4) The temperature of the cryogenic stage liquid receiver 104 is below 10℃.

[0058] Defrosting process: Defrosting begins when defrosting conditions are met → Defrosting bypass valve 5 opens → Water pump 34 in heat storage system 3 starts → Evaporator fan 108 shuts down after a 2-second delay, while the opening of low-temperature stage main circuit electronic expansion valve 105 is fixed at step 250 → Low-temperature stage compressor 101 speed is fixed at 3000 rpm → High-temperature stage compressor 201 shuts down after a 2-second delay → Defrosting process completes → Defrosting end conditions are detected → Defrosting bypass valve 5 and water pump 34 in heat storage system 3 shut down → Low-temperature stage compressor 101 shuts down after a 2-second delay → Compressor anti-frequent start time (default 3 minutes) passes → Unit restarts.

[0059] The evaporator fan 108 has a maximum total air volume of 100%. It uses two fans to combine the air volume from 10% to 100%. One fan is a fixed-speed fan with an air volume of 50%, and the other fan is an EC speed-regulating fan with an air volume of 10-50%. The air volume adjustment range is large to meet the stable operation under different working conditions. When the unit receives the start command, the EC speed-regulating fan is turned on first with an initial speed of 30%. After the unit compressor starts, it enters the automatic fan adjustment mode.

[0060] When the evaporator fan 108 automatically adjusts, the unit adjusts based on a comparison between the setpoint and the actual evaporation pressure of the low-temperature stage. A PID control method is used, with a PID output range of 10-100%. When the evaporation pressure is greater than the setpoint, the airflow is reduced; when the evaporation pressure is less than the setpoint, the airflow is increased. The low-temperature stage evaporation pressure is always maintained within the range of 8.0 Bar ± 0.1. Several examples are given below:

[0061] When the output value is 10%, the constant speed fan is off at 0%, and the variable speed fan runs at 10%.

[0062] When the output value is 30%, the constant speed fan is off at 0%, and the variable speed fan runs at 30%.

[0063] When the output value is 50%, the constant speed fan is off at 0%, and the variable speed fan is running at 50%.

[0064] When the output value is 60%, the constant speed fan operates at 50% and the variable speed fan operates at 10%.

[0065] When the output value is 70%, the constant speed fan operates at 50% and the variable speed fan operates at 20%.

[0066] When the output value is 85%, the constant speed fan operates at 50% and the variable speed fan operates at 35%.

[0067] When the output value is 100%, the constant speed fan is 50% open and the variable speed fan is 50% open.

Claims

1. An ultra-high temperature hot water device, comprising a low-temperature stage heating system (1), a high-temperature stage heating system (2), a heat storage system (3), and a control system, characterized in that: A plate condenser evaporator (4) is provided between the low-temperature heating system (1) and the high-temperature heating system (2). One side of the plate condenser evaporator (4) is connected to the low-temperature heating system (1), and the other side of the plate condenser evaporator (4) is connected to the high-temperature heating system (2). The low-temperature heating system (1) absorbs heat from an external low-temperature heat source, and the high-temperature heating system (2) absorbs heat from the plate condenser evaporator (4). The heat storage system (3) includes a low-temperature storage tank (31) and a high-temperature storage tank (32). The tank (31) and the high-temperature storage tank (32) are connected in series via a pipeline (33), which contains a water pump (34) and a defrosting water temperature sensor (35). The low-temperature storage tank (31) is connected to the low-temperature heating system (1) via a low-temperature inlet solenoid valve (36) and a low-temperature outlet solenoid valve (37). The high-temperature storage tank (32) is connected to the high-temperature heating system (2) via a high-temperature inlet solenoid valve (38) and a high-temperature outlet solenoid valve (39). The heat storage system (3) is connected to the low-temperature heating system (1) via a pipeline (33). There is a defrost bypass valve (5). When the ambient temperature and the defrost temperature sensor reach the defrost timing requirement, the high-temperature stage inlet solenoid valve (38) and the high-temperature stage outlet solenoid valve (39) open, the water pump (34) runs, and the high-temperature stage liquid refrigerant flows through the high-temperature stage storage tank (32) to heat the water. The water pump (34) then delivers the water to the low-temperature stage storage tank (31). After multiple cycles, the water in the heat storage system (3) is gradually heated to the predetermined temperature for use during defrosting. When the water temperature in the heat storage system (3) reaches about 70°C, the high-temperature stage inlet solenoid valve (38) opens. 8) When the high-temperature stage liquid outlet solenoid valve (39) is closed, the heat storage system (3) stops operating; when the defrosting conditions are met, the high-temperature stage liquid outlet solenoid valve (39) opens, and the water pump (34) starts to run. The water in the pipeline (33) flows between the low-temperature stage liquid storage tank (31) and the high-temperature stage liquid storage tank (32), gradually heating the water used for defrosting; during defrosting, the three solenoid valves, the low-temperature stage liquid inlet solenoid valve (36), the low-temperature stage liquid outlet solenoid valve (37) and the defrost bypass valve (5), open, and the hotter refrigerant liquid enters the low-temperature stage heating system (1) to start defrosting.

2. The ultra-high temperature hot water device according to claim 1, characterized in that: The low-temperature heating system (1) includes a low-temperature compressor (101), an oil separator (102), a plate condenser evaporator (4), a low-temperature liquid receiver (103), a low-temperature economizer (104), a low-temperature main electronic expansion valve (105), a low-temperature auxiliary electronic expansion valve (106), an evaporator (107), an evaporator fan (108), a gas-liquid separator (109), a temperature sensor (110), a pressure sensor (111), and a pressure switch (112). The low-temperature auxiliary electronic expansion valve (106) is connected to the low-temperature economizer (104), and the outlet pipe of the low-temperature compressor (101) is connected to the low-temperature pipe of the plate condenser evaporator (4).

3. The ultra-high temperature hot water device according to claim 2, characterized in that: The low-temperature stage compressor (101) is a variable frequency scroll compressor, and the evaporator (107) is a V-shaped combined fin evaporator.

4. The ultra-high temperature hot water device according to claim 1, characterized in that: The high-temperature heating system (2) includes a high-temperature compressor (201), a plate condenser (202), a plate condenser evaporator (4), a high-temperature gas-liquid separator (203), a high-temperature economizer (204), a high-temperature liquid receiver (205), a high-temperature main circuit electronic expansion valve (206), and a high-temperature auxiliary circuit electronic expansion valve (207). The high-temperature auxiliary circuit electronic expansion valve (207) is connected to the high-temperature economizer (204), and the inlet pipe of the high-temperature compressor (201) is connected to the high-temperature pipeline of the plate condenser evaporator (4).

5. The ultra-high temperature hot water device according to claim 4, characterized in that: The high-temperature compressor (201) is a scroll compressor with high condensing temperature and high evaporating temperature.

6. The ultra-high temperature hot water device according to claim 1, characterized in that: The control system adopts Siemens SMART200 series PLC and Kunlun Tongtai HMI human-machine interface. The control system can realize the control of low temperature stage compressor, high temperature stage compressor, low temperature stage main circuit electronic expansion valve, low temperature stage auxiliary circuit electronic expansion valve, high temperature stage main circuit electronic expansion valve, high temperature stage auxiliary circuit electronic expansion valve, evaporator fan control and fault handling control.

7. A smart control method for an ultra-high temperature hot water device according to any one of claims 1 to 6, characterized in that: Includes the following steps: ① Start-up control: First, start the evaporator fan (108). Determine the starting sequence of the high-temperature stage compressor (201) and the low-temperature stage compressor (101) based on the high-temperature stage evaporation temperature. When the detected high-temperature stage evaporation temperature is ≥15℃, start the high-temperature stage compressor (201) first, and then start the low-temperature stage compressor (101) after 5 seconds. When the detected high-temperature stage evaporation temperature is <15℃, start the low-temperature stage compressor (101) first, and then start the high-temperature stage compressor (201) after the detected high-temperature stage evaporation temperature is ≥20℃. ② The low-temperature compressor (101) is controlled by frequency converter. The initial speed of the low-temperature compressor (101) is 2400 rpm, and it maintains this speed for 3 minutes before switching to automatic adjustment mode to ensure that the low-temperature compressor (101) and the high-temperature compressor (201) operate within their respective allowable operating ranges. ③ Low temperature stage and high temperature stage main circuit electronic expansion valve control: After the evaporator fan (108) starts, before the low temperature stage compressor (101) and high temperature stage compressor (201) start, the low temperature stage main circuit electronic expansion valve (105) and the high temperature stage main circuit electronic expansion valve (206) are opened in advance at 30% opening degree. After the low temperature stage compressor (101) and the high temperature stage compressor (201) start, the evaporation pressure and suction temperature of the main circuit are detected and converted into evaporation temperature. The superheat is calculated and compared with the preset superheat. The opening degree of the low temperature stage main circuit electronic expansion valve (105) and the high temperature stage main circuit electronic expansion valve (206) is automatically adjusted according to the superheat difference. ④ Low temperature stage and high temperature stage auxiliary circuit electronic expansion valve control: When the low temperature stage compressor (101) and the high temperature stage compressor (201) are started, the evaporation pressure is converted into evaporation temperature by detecting the evaporation pressure and suction temperature of the auxiliary circuit, the superheat is calculated and compared with the preset superheat, and the opening degree of the low temperature stage auxiliary circuit electronic expansion valve (106) and the high temperature stage auxiliary circuit electronic expansion valve (207) is automatically adjusted according to the superheat difference. ⑤ Defrosting control: The following conditions must be met simultaneously to initiate defrosting: (1) The running time of both the low-temperature stage compressor (101) and the high-temperature stage compressor (201) is ≥7 minutes; (2) The difference between the ambient temperature and the fin temperature of the evaporator (107) in the low-temperature heating system (1) is ≥10℃; (3) Ambient temperature ≤ 5℃; (4) The fin temperature of the evaporator (107) in the low-temperature heating system (1) is ≤-2℃; (5) When the defrosting interval is ≥45 minutes and the temperature of the evaporator (107) fins in the low-temperature heating system (1) is ≤0℃, the defrosting interval starts to be counted. If the temperature of the evaporator (107) fins is ≥2℃ for 3 minutes during the counting process, the defrosting time is reset to zero. Defrosting will end if any of the following conditions are met: (1) The fin temperature of the evaporator (107) in the low-temperature heating system (1) is ≥15℃; (2) Defrosting time ≥ 10 minutes; (3) High-pressure protection for the cryogenic compressor (101); (4) The temperature of the cryogenic reservoir (103) is below 10℃.

8. The intelligent control method for the ultra-high temperature hot water device according to claim 7, characterized in that: The evaporator fan (108) has a maximum total air volume of 100%. It uses two fans to form an air volume of 10~100%. One fan is a fixed speed fan with an air volume of 50%, and the other fan is an EC speed regulating fan with an air volume of 10-50%. The air volume adjustment range is large to meet the stable operation under different working conditions. When the unit receives the start command, the EC speed regulating fan is turned on first with an initial speed of 30%. After the unit compressor starts, it enters the automatic fan adjustment mode.

9. The intelligent control method for the ultra-high temperature hot water device according to claim 8, characterized in that: When the evaporator fan (108) is automatically adjusted, the unit adjusts according to the comparison between the set value of the low-temperature stage evaporation pressure and the actual evaporation pressure. The PID adjustment method is adopted, and the PID output range is 10-100%. When the evaporation pressure is greater than the set value, the air volume is reduced; when the evaporation pressure is less than the set value, the air volume is increased. The low-temperature stage evaporation pressure is always kept within the range of 8.0 Bar ± 0.1.

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