Cold and hot dual-output temperature control heat pump device and control method thereof

Abstract

The invention discloses a cold and hot dual-output temperature control heat pump device and a control method thereof, and relates to the technical field of agricultural product processing equipment.The device comprises a cold and hot supply system, a drying chamber and a cooling chamber, the cold and hot supply system forms a heat pump circulation loop through a compressor, a condenser, an evaporator and the like, and the condenser conveys hot air to the drying chamber through a heat supply pipe; the evaporator conveys cold air to the cooling chamber through the cooling pipe, the integrated design of the drying process and the cooling process is achieved, the heating pipe and the cooling pipe are each provided with a frequency conversion fan, the air mass flow needed by each chamber is calculated through the controller, the air volume of the corresponding frequency conversion fan is adjusted, and precise temperature control is achieved. The drying and cooling requirements are met simultaneously through the heat pump technology, the energy utilization efficiency is remarkably improved, the equipment investment cost is reduced, and the device is suitable for large-scale agricultural product drying and cooling treatment.

Description

Technical Field

[0001] This invention relates to the field of agricultural product processing equipment technology, and in particular to a dual-output (cold and hot) temperature-controlled heat pump device and its control method. Background Technology

[0002] In the field of agricultural product storage, moisture content plays a crucial role in its quality and storage time. To extend the quality cycle of agricultural products, timely drying to a safe moisture content after harvest is a commonly used and important method in the industry. Currently, commonly used agricultural product drying methods include natural sun-drying, hot air drying (electric heating, coal-fired heating, biomass heating, heat pump heating), infrared drying, and microwave drying. Natural sun-drying is greatly constrained by weather and other natural conditions, has low efficiency, and makes it difficult to guarantee the consistency of dried quality; infrared drying and microwave drying equipment are costly and energy-intensive, limiting their application in large-scale agricultural product drying; electric heating, coal-fired heating, and biomass heating methods in hot air drying have problems such as high energy consumption and significant pollution.

[0003] In contrast, heat pump drying, as a highly efficient energy utilization method, demonstrates unique advantages in agricultural product drying. When the ambient temperature is high, the thermal efficiency of heat pumps is high, effectively reducing energy consumption. However, some high-value agricultural products need to be cooled to ambient temperature after drying before being transported to cold storage for low-temperature storage. In existing agricultural product drying processes, the drying and cooling stages are independent, requiring separate drying and cooling equipment. This not only increases equipment investment costs but also consumes a large amount of energy during the cooling process, resulting in low energy efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-output (cold and hot) temperature-controlled heat pump device and its control method to solve the problems existing in the prior art and improve the energy utilization efficiency of drying and cooling agricultural products before storage.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a dual-output temperature-controlled heat pump device, including a hot and cold supply system, a drying chamber, and a cooling chamber, wherein both the drying chamber and the cooling chamber are used to contain agricultural products;

[0007] The heating and cooling supply system includes a compressor, a condenser, a liquid tank, a dryer filter, an expansion valve, an evaporator, and a gas-liquid separator connected in sequence. The outlet of the gas-liquid separator is connected to the inlet of the compressor. The condenser is provided with a first inlet for introducing a first ambient air. The condenser is connected to the drying chamber through a heating pipe, and the first ambient air heated by the condenser is introduced into the drying chamber through the heating pipe. The evaporator is provided with a second inlet for introducing a second ambient air. The evaporator is connected to the cooling chamber through a cooling pipe, and the second ambient air cooled by the evaporator is introduced into the cooling chamber through the cooling pipe.

[0008] The heating and cooling supply system also includes a controller. Variable frequency fans are installed on the heating pipe and the cooling pipe respectively. Flow sensors and temperature and humidity sensors are installed on the air outlets of the heating pipe and the cooling pipe. Each flow sensor, each temperature and humidity sensor, and each variable frequency fan inverter are connected to the controller via signal connection.

[0009] Preferably, the drying chamber includes a primary drying chamber and a secondary drying chamber; the condenser includes a first sub-condenser and a second sub-condenser arranged in series and isolated from each other, and both the first sub-condenser and the second sub-condenser are provided with the first air inlet; the heating pipe includes a first heating pipe and a second heating pipe, and both the first heating pipe and the second heating pipe are provided with the variable frequency fan; the first sub-condenser is connected to the primary drying chamber through the first heating pipe, and the second sub-condenser is connected to the secondary drying chamber through the second heating pipe;

[0010] The second sub-condenser is equipped with multiple electric heating tubes for heating the first ambient air, and the controller can control the opening and closing of any of the electric heating tubes.

[0011] Preferably, each of the first air inlets is provided with a filter screen.

[0012] Preferably, the condenser includes a first housing, and the first sub-condenser and the second sub-condenser are both disposed within the first housing. A first partition is disposed within the first housing, and the first sub-condenser and the second sub-condenser are separated by the first partition.

[0013] Preferably, the cooling chamber includes a primary cooling chamber and a secondary cooling chamber; the evaporator includes a first sub-evaporator and a second sub-evaporator arranged in series and isolated from each other, with the first sub-evaporator being closer to the gas-liquid separator than the second sub-evaporator; both the first and second sub-evaporators are provided with a second air inlet; the cooling pipe includes a first cooling pipe and a second cooling pipe, both of which are equipped with the variable frequency fan; the first sub-evaporator is connected to the primary cooling chamber through the first cooling pipe, and the second sub-evaporator is connected to the secondary cooling chamber through the second cooling pipe.

[0014] Preferably, each of the second air inlets is provided with a filter screen.

[0015] Preferably, the evaporator includes a second housing, and both the first sub-evaporator and the second sub-evaporator are disposed within the second housing. A second partition is disposed within the second housing, and the first sub-evaporator and the second sub-evaporator are separated by the second partition.

[0016] The present invention also provides a control method for the above-mentioned dual-output temperature-controlled heat pump device: the outlet heat flow rate of the first sub-condenser is the first outlet heat flow rate, and the variable frequency fan on the first heating pipe is the first variable frequency fan; the controller calculates the first outlet heat flow rate based on the current temperature of the outlet of the first sub-condenser, the ambient temperature, and the current air mass flow rate of the first variable frequency fan; the controller calculates the required air mass flow rate of the first variable frequency fan based on the first outlet heat flow rate, the ambient temperature, and the required drying temperature of the first-stage drying chamber; and the controller controls the first variable frequency fan to achieve the required air mass flow rate.

[0017] The heat flow rate of the air outlet of the second sub-condenser is the second air outlet heat flow rate, and the variable frequency fan on the second heating pipe is the second variable frequency fan. The controller calculates the second air outlet heat flow rate based on the current temperature of the air outlet of the second sub-condenser, the ambient temperature, and the current air mass flow rate of the second variable frequency fan. The controller also calculates the required air mass flow rate of the second variable frequency fan based on the second air outlet heat flow rate, the ambient temperature, and the required drying temperature of the secondary drying chamber. Finally, the controller controls the second variable frequency fan to achieve the required air mass flow rate.

[0018] The first outlet air cooling flow rate of the first sub-evaporator is the first outlet air cooling flow rate, and the variable frequency fan on the first heating pipe is the third variable frequency fan. The controller calculates the first outlet air cooling flow rate based on the current temperature of the first sub-evaporator outlet, the ambient temperature, and the current air mass flow rate of the third variable frequency fan. The controller also calculates the required air mass flow rate of the third variable frequency fan based on the first outlet air cooling flow rate, the ambient temperature, and the required cooling temperature of the first-stage cooling chamber. Finally, the controller controls the third variable frequency fan to achieve the required air mass flow rate.

[0019] The cold air flow rate at the outlet of the second sub-evaporator is the second cold air flow rate, and the variable frequency fan on the second heating pipe is the fourth variable frequency fan. The controller calculates the second cold air flow rate based on the current temperature at the outlet of the second sub-evaporator, the ambient temperature, and the current air mass flow rate of the fourth variable frequency fan. The controller also calculates the required air mass flow rate of the fourth variable frequency fan based on the second cold air flow rate, the ambient temperature, and the required cooling temperature of the secondary cooling chamber. Finally, the controller controls the fourth variable frequency fan to achieve the required air mass flow rate.

[0020] Preferably, the calculation process for the air mass flow rate required by the first variable frequency fan includes the following steps:

[0021] S1. Calculate the first outlet air heat flow rate Q. 热 The calculation formula is as follows:

[0022] Q 热 =q0*C 空气 (T1-T0) (1)

[0023] In formula (1): Q 热 q0 is the first outlet air heat flow rate, kJ / h; q0 is the current air mass flow rate delivered by the first variable frequency fan, in kg / h; C 空气 T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the outlet temperature of the first condenser, in ℃; T3 is the ambient temperature, in ℃.

[0024] S2. Based on the required drying temperature T2 of the primary drying chamber, calculate the required air mass flow rate q1 of the first variable frequency fan. The calculation formula is as follows:

[0025]

[0026] In formula (2): Q 热 q1 represents the total heat flow rate of the hot air, expressed in kJ / h; q1 represents the required air mass flow rate of the first variable frequency fan, expressed in kg / h; C 空气T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the required drying temperature of the primary drying chamber, in ℃; T0 is the ambient temperature, in ℃.

[0027] The present invention achieves the following technical effects compared to the prior art:

[0028] The present invention relates to a dual-output (cold and hot) temperature-controlled heat pump device and its control method, which achieves material drying and subsequent cooling by rationally utilizing the cold and hot air generated by the cold and hot supply system, thereby improving energy utilization efficiency.

[0029] Furthermore, existing cooling methods for agricultural products tend to expose the materials to air for too long, increasing the risk of moisture absorption and rehydration, making it difficult to maintain the high quality of the agricultural products. The dual-output (hot and cold) temperature-controlled heat pump device and its control method of this invention, by integrating a drying chamber and a cooling chamber, not only improves energy utilization efficiency but also allows for cooling of the materials immediately after drying, reducing the exposure time of the materials to the environment and helping to maintain the quality of the dried materials. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of the dual-output (cold and hot) temperature-controlled heat pump device of the present invention;

[0032] In the diagram: 1. Compressor; 2. Condenser; 3. First air inlet; 4. Electric heating element; 5. Frequency converter; 6. Primary drying chamber; 7. Secondary drying chamber; 8. Secondary cooling chamber; 9. Primary cooling chamber; 10. Temperature and humidity sensor; 11. Variable frequency fan; 12. Controller; 13. Liquid tank; 14. Dryer filter; 15. Expansion valve; 16. Evaporator; 17. Gas-liquid separator. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a dual-output (cold and hot) temperature-controlled heat pump device and its control method to solve the problems existing in the prior art and improve the energy utilization efficiency of drying and cooling agricultural products before storage.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a dual-output temperature-controlled heat pump device, including a hot and cold supply system, a drying chamber, and a cooling chamber, wherein the drying chamber and the cooling chamber are used to contain agricultural products to be processed.

[0038] The heating and cooling supply system is the core component of the device, comprising a compressor 1, a condenser 2, a liquid tank 13, a dryer filter 14, an expansion valve 15, an evaporator 16, and a gas-liquid separator 17 connected in sequence. The outlet of the gas-liquid separator 17 is connected to the inlet of the compressor 1, forming a complete circulation loop. The condenser 2 is provided with a first inlet 3 for introducing first ambient air. The first ambient air, heated by the condenser 2, is introduced into the drying chamber through a heating pipe. The evaporator 16 is provided with a second inlet for introducing second ambient air. The second ambient air, cooled by the evaporator 16, is introduced into the cooling chamber through a cooling pipe. In addition, the heating and cooling supply system is equipped with a controller 12, and variable frequency fans 11 are installed on the heating pipe and the cooling pipe respectively. The variable frequency fans 11 are used to provide power for the gas flow in the heating pipe and the cooling pipe. Specifically, the first ambient air heated by the condenser 2 is pumped into the drying chamber through the heating pipe, and the second ambient air cooled by the evaporator 16 is pumped into the cooling chamber through the cooling pipe. Flow sensors and temperature and humidity sensors 10 are installed on the air outlets of the heating pipe and the cooling pipe. These sensors and the frequency converter 5 of the variable frequency fan 11 are all connected to the controller 12 for signal connection in order to achieve precise control.

[0039] In the optional scheme of this embodiment, a preferred embodiment is that the drying chamber specifically includes a primary drying chamber 6 and a secondary drying chamber 7. Correspondingly, the condenser 2 includes a first sub-condenser and a second sub-condenser arranged in series and isolated from each other. Both are provided with a first air inlet 3, and the heating pipes are also correspondingly divided into a first heating pipe and a second heating pipe, and both are equipped with a variable frequency fan 11. The first sub-condenser is connected to the primary drying chamber 6 through the first heating pipe, and the second sub-condenser is connected to the secondary drying chamber 7 through the second heating pipe. In order to further improve the drying effect, multiple electric heating tubes 4 are provided in the second sub-condenser. The controller 12 can control the opening and closing of any electric heating tube 4 according to actual needs, thereby flexibly adjusting the heating temperature of the secondary drying chamber 7. At the same time, in order to prevent impurities in the environment from entering the condenser 2, a filter screen is provided on each first air inlet 3. Flow sensors and temperature and humidity sensors 10 are provided at the air outlets of the first and second heating pipes.

[0040] In the optional embodiments of this example, a preferred embodiment includes a primary cooling chamber 9 and a secondary cooling chamber 8. The evaporator 16 includes a first sub-evaporator and a second sub-evaporator connected in series and isolated from each other. The first sub-evaporator is closer to the gas-liquid separator 17 than the second sub-evaporator. Both sub-evaporators have a second air inlet. The cooling pipes are also divided into a first cooling pipe and a second cooling pipe, and both are equipped with a variable frequency fan 11. The first sub-evaporator is connected to the primary cooling chamber 9 through the first cooling pipe, and the second sub-evaporator is connected to the secondary cooling chamber 8 through the second cooling pipe. Similarly, each second air inlet is equipped with a filter screen to ensure that the air entering the evaporator 16 is clean. Flow sensors and temperature and humidity sensors 10 are installed at the air outlets of both the first and second cooling pipes.

[0041] In this embodiment, in terms of specific structural design, the condenser 2 includes a first housing, and both a first sub-condenser and a second sub-condenser are disposed within the first housing. A first partition is provided within the first housing to effectively separate the first sub-condenser and the second sub-condenser, ensuring that they operate independently. All first air inlets 3 are located on the first housing. The evaporator 16 includes a second housing, and both a first sub-evaporator and a second sub-evaporator are disposed within the second housing. A second partition is provided within the second housing to separate the first sub-evaporator and the second sub-evaporator, ensuring their respective operational stability. All second air inlets are located on the second housing.

[0042] The working principle of the dual-output (cold and hot) temperature-controlled heat pump device in this embodiment is as follows:

[0043] In actual operation, after the device is started, the heating and cooling supply system begins to work. Compressor 1 compresses the low-temperature, low-pressure refrigerant gas into a high-temperature, high-pressure refrigerant gas, which flows sequentially through the first and second sub-condensers. In the first and second sub-condensers, the high-temperature, high-pressure refrigerant gas exchanges heat with the first ambient air entering from the first air inlet 3. After being heated, the first ambient air is sent to the primary drying chamber 6 and the secondary drying chamber 7 through the first and second heating pipes, respectively, to dry the agricultural products. The temperature of the output hot air is controlled by adjusting the airflow of the variable frequency fan 11 on the first and second heating pipes. The secondary drying chamber 7 can be controlled by the controller 12 to open and close the electric heating tubes 4 in the second sub-condenser, i.e., the number of electric heating tubes 4 that are turned on, to further adjust the drying temperature. The material that has completed the primary drying in the primary drying chamber 6 is transferred to the secondary drying chamber 7 for secondary drying. By reasonably controlling the temperature difference through two-stage drying, the material is dried in stages to prevent damage to the material due to excessive temperature difference. Staged drying is beneficial to improving the quality of the dried material.

[0044] Meanwhile, the high-temperature, high-pressure refrigerant gas passing through condenser 2 becomes low-temperature, high-pressure refrigerant liquid, flows into liquid tank 13, and then passes through dryer filter 14 to remove moisture from the refrigerant. It then enters expansion valve 15, where its pressure and temperature are reduced before entering evaporator 16. In evaporator 16, the refrigerant liquid flows sequentially through the second sub-evaporator and the first sub-evaporator, exchanging heat with the second ambient air entering from the second inlet. After being cooled, the second ambient air is sent to the primary cooling chamber 9 and the secondary cooling chamber 8 through the first and second cooling pipes, respectively, to cool the dried agricultural products. After absorbing heat in evaporator 16, the refrigerant liquid becomes low-pressure, low-temperature gas. Finally, the low-pressure, low-temperature refrigerant gas enters gas-liquid separator 17 from evaporator 16, and the refrigerant returns to compressor 1 from gas-liquid separator 17, completing the refrigeration cycle.

[0045] After secondary drying in the secondary drying chamber 7, the material is placed for 4-5 hours and then transferred to the primary cooling chamber 9 for primary cooling. The material that has completed primary cooling in the primary cooling chamber 9 is then transferred to the secondary cooling chamber 8 for secondary cooling. The temperature difference is reasonably controlled through two-stage cooling to prevent thermal stress damage to the material caused by excessive temperature difference. The temperature of the cold air is controlled by the ambient air flow rate controlled by the frequency converter 5. When the required cooling air temperature is low, the ambient air flow rate is reduced, and vice versa, when the required cooling air temperature is high, the ambient air flow rate is increased.

[0046] Example 2

[0047] This embodiment provides a control method for a dual-output (cold and hot) temperature-controlled heat pump device according to Embodiment 1. The specific implementation is as follows: the heat flow rate of the air outlet of the first sub-condenser is the first heat flow rate, and the variable frequency fan on the first heating pipe is the first variable frequency fan; the controller 12 calculates the first heat flow rate based on the current temperature of the air outlet of the first sub-condenser, the ambient temperature, and the current air mass flow rate of the first variable frequency fan; the controller 12 calculates the air mass flow rate that the first variable frequency fan needs to achieve based on the first heat flow rate, the ambient temperature, and the drying temperature required by the primary drying chamber 6; and the controller 12 controls the first variable frequency fan to achieve the required air mass flow rate.

[0048] The heat flow rate of the air outlet of the second sub-condenser is called the second air outlet heat flow rate, and the variable frequency fan on the second heating pipe is called the second variable frequency fan. The controller 12 calculates the second air outlet heat flow rate based on the current temperature of the air outlet of the second sub-condenser, the ambient temperature, and the current air mass flow rate of the second variable frequency fan. The controller 12 calculates the air mass flow rate that the second variable frequency fan needs to achieve based on the second air outlet heat flow rate, the ambient temperature, and the drying temperature required by the secondary drying chamber 7. The controller 12 controls the second variable frequency fan to achieve the required air mass flow rate.

[0049] The first outlet air cooling flow rate is the first outlet air cooling flow rate, and the variable frequency fan on the first heating pipe is the third variable frequency fan. The controller 12 calculates the first outlet air cooling flow rate based on the current temperature of the first outlet air of the first sub-evaporator, the ambient temperature, and the current air mass flow rate of the third variable frequency fan. The controller 12 calculates the air mass flow rate that the third variable frequency fan needs to achieve based on the first outlet air cooling flow rate, the ambient temperature, and the cooling temperature required by the first-stage cooling chamber 9. The controller 12 controls the third variable frequency fan to achieve the required air mass flow rate.

[0050] The cold air flow rate at the outlet of the second sub-evaporator is the second cold air flow rate, and the variable frequency fan on the second heating pipe is the fourth variable frequency fan. The controller 12 calculates the second cold air flow rate based on the current temperature of the outlet of the second sub-evaporator, the ambient temperature, and the current air mass flow rate of the fourth variable frequency fan. The controller 12 calculates the required air mass flow rate of the fourth variable frequency fan based on the second cold air flow rate, the ambient temperature, and the required cooling temperature of the secondary cooling chamber 8. The controller 12 controls the fourth variable frequency fan to achieve the required air mass flow rate.

[0051] Taking the primary drying chamber 6 as an example, the calculation process for the required air mass flow rate of the first variable frequency fan includes the following steps:

[0052] S1. Calculate the first outlet air heat flow rate Q. 热 The calculation formula is as follows:

[0053] Q热 =q0*C 空气 (T1-T0) (1)

[0054] In formula (1): Q 热 q0 is the first outlet air heat flow rate, kJ / h; q0 is the current air mass flow rate delivered by the first variable frequency fan, in kg / h; C 空气 T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the outlet temperature of the first condenser, in ℃; T3 is the ambient temperature, in ℃.

[0055] S2. Based on the required drying temperature T2 of the primary drying chamber, calculate the required air mass flow rate q1 of the first variable frequency fan. The calculation formula is as follows:

[0056]

[0057] In formula (2): Q 热 q1 represents the first outlet air heat flow rate, in kJ / h; q1 represents the air mass flow rate required by the first variable frequency fan, in kg / h; C 空气 T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the required drying temperature for the first-stage drying chamber 6, in ℃; T0 is the ambient temperature, in ℃.

[0058] The temperature in the secondary drying chamber 7 can be regulated by both temperature and humidity.

[0059] The temperature control method in the secondary drying chamber 7 is as follows:

[0060] First, based on the required drying temperature T2, similar to steps S1 and S2, the required air mass flow rate q1 for the second variable frequency fan can be calculated; the lower limit threshold for the operating efficiency of the second variable frequency fan is set as follows. At this point, the minimum airflow threshold for the second variable frequency fan is q. a The relationship between the efficiency of the second variable frequency fan and the minimum threshold of the air volume of the second variable frequency fan is as follows:

[0061]

[0062] In the formula: The lower limit threshold for the operating efficiency of the second variable frequency fan; q a This is the minimum threshold for the air volume of the second variable frequency fan, expressed in kg / h.

[0063] If q1 is greater than q a The second variable frequency fan operates normally, generating an air volume of q1; otherwise, the second variable frequency fan is adjusted to q. a At this time, the heat flow difference is Q. 补The heat generated is supplied by multi-stage electric heating tubes 4, and each stage of the multi-stage electric heating tubes 4 generates Q heat. a According to the required heat flow difference Q 补 The number of starting stages, n, for a multi-stage electric heating element with four stages is calculated as follows:

[0064] Q 补 =(q a -q1)*C 空气 (T2-T0)

[0065] n = Q 补 / Q a

[0066] In the formula, Q 补 This represents the difference in heat flow, expressed in kJ / h; q a Q represents the minimum airflow threshold for the second variable frequency fan, in kg / h; q1 represents the airflow generated by the second variable frequency fan during normal operation, in kg / h; Q a The heat generated per stage of the multi-stage electric heating tube is expressed in kJ / h; C 空气 T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the required drying temperature, in ℃; T0 is the ambient air temperature, in ℃; n is the number of stages of the multi-stage electric heating tube 4 that need to be activated, and this value is rounded up.

[0067] The humidity control method in the secondary drying chamber 7 is as follows:

[0068] First, the second variable frequency fan operates normally, generating hot air flow rate q, temperature T3, and humidity η, which are directly measured by sensors; at this time, the saturated water vapor partial pressure is P0, calculated as follows:

[0069]

[0070] In the formula, P0 is the partial pressure of saturated water vapor, in kPa; T3 is the Kelvin temperature of hot air, in K.

[0071] The target humidity of hot air is η 终 To achieve this target humidity level, we first need to calculate the partial pressure P of water vapor in the air at this time. air The calculation method is as follows

[0072] P air =η*P0

[0073] In the formula, η is the current humidity of the hot air; P0 is the partial pressure of saturated water vapor, in kPa.

[0074] At this point, based on the target's air humidity η 终 Calculate the saturated water vapor partial pressure P at this time. 终 The calculation method is as follows

[0075]

[0076] Then, increase T3 by 1°C and calculate the saturated water vapor partial pressure P0 at this time. If P 终 The difference between P0 and T3 is greater than 5%; if T3 continues to increase by 1℃, calculate P. 终 The difference between P0 and P0 is used to repeat the above steps until P is reached. 终 If the difference between P0 and P0 is less than 5%, then output T3 at this point;

[0077] At this time, the heat flow provided by electric heating element 4 is Q. 补2 The number of starting stages n2 for the multi-stage electric heating element 4 is calculated as follows:

[0078] Q 补2 =q*C 空气 (T3-273.2-T0)

[0079] n2=Q 补2 / Q a

[0080] In the formula, Q 补2 The heat flow rate provided to the electric heating element 4 is in kJ / h; T3 is the Kelvin temperature of the hot air in K; n2 is the number of starting stages of the multi-stage electric heating element 4, where n2 is rounded up to the nearest integer.

[0081] Step 3: Next, the dried material needs to undergo two stages of cooling.

[0082] First-stage cooling is the initial cooling process, with a target temperature of T. 冷1 The calculation method is as follows:

[0083] (1) The third variable frequency fan is running normally. At this time, the output air volume of the third variable frequency fan is q0. Calculate the first outlet air cooling flow rate Q. 冷1 The calculation method is shown in the following formula:

[0084] Q 冷1 =q0*C 空气 (T0-T 冷0 )

[0085] In the formula: Q 冷1 q0 represents the first outlet air cooling flow rate, in kW; q0 represents the current air mass flow rate of the third variable frequency fan, in kg / h; C 空气 T represents the specific heat capacity of air, expressed in kJ / (kg*℃). 冷0 T0 represents the cold air temperature at the outlet of the first sub-evaporator, in °C; T0 represents the ambient temperature, in °C.

[0086] (2) Based on the required cooling temperature T of the primary cooling chamber 9 冷1The air volume of the third variable frequency fan is adjusted to q via controller 12. 冷1 The calculation method is as follows:

[0087]

[0088] In the formula: Q 冷1 The first outlet air cooling flow rate is expressed in kJ / h; q 冷1 The required air mass flow rate for the third variable frequency fan, expressed in kg / h; C 空气 T represents the specific heat capacity of air, expressed in kJ / (kg*℃). 冷1 T0 represents the required cooling temperature for the primary cooling chamber 9, in °C; T0 represents the ambient temperature, in °C.

[0089] Secondary cooling is the final cooling, with a target temperature of T. 冷2 The calculation method is as follows:

[0090] (1) The fourth variable frequency fan is running normally. At this time, the output air volume of the fourth variable frequency fan is q0. Calculate the second outlet air cooling flow rate Q. 冷2 The calculation method is shown in the following formula:

[0091] Q 冷2 =q0*C 空气 (T0-T 冷3 )

[0092] In the formula: Q 冷1 The second outlet air cooling flow rate is expressed in kW; q0 is the current air mass flow rate of the fourth variable frequency fan, expressed in kg / h; C 空气 T represents the specific heat capacity of air, expressed in kJ / (kg*℃). 冷3 T0 represents the cold air temperature at the outlet of the second sub-evaporator, in °C; T0 represents the ambient temperature, in °C.

[0093] (2) Based on the required cooling temperature T of the secondary cooling chamber 8 冷2 The fourth variable frequency fan is adjusted to q via controller 12. 冷2 The calculation method is as follows:

[0094]

[0095] In the formula: Q 冷2 The second outlet air cooling flow rate is expressed in kJ / h; q 冷2 The required air mass flow rate for the fourth variable frequency fan is expressed in kg / h; C 空气 T represents the specific heat capacity of air, expressed in kJ / (kg*℃). 冷2 T0 is the temperature required for the secondary cooling chamber 8, in °C; T0 is the ambient temperature, in °C.

[0096] Throughout the drying and cooling process, flow sensors and temperature and humidity sensors 10 at the outlets of the heating and cooling pipes monitor the air flow, temperature, and humidity data in real time and transmit the data to the controller 12. Based on preset drying and cooling parameters and the calculated air mass flow rate required for each chamber (i.e., primary drying chamber 6, secondary drying chamber 7, primary cooling chamber 9, and secondary cooling chamber 8), the controller 12 precisely adjusts the inverter 5 of the corresponding variable frequency fan 11, thereby controlling the air volume delivered by the corresponding variable frequency fan 11. This ensures that agricultural products complete drying and cooling under suitable environmental conditions, effectively improving energy efficiency.

[0097] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A dual-output (cold and hot) temperature-controlled heat pump device, characterized in that: It includes a hot and cold supply system, a drying chamber, and a cooling chamber, both of which are used to contain agricultural products; The heating and cooling supply system includes a compressor, a condenser, a liquid tank, a dryer filter, an expansion valve, an evaporator, and a gas-liquid separator connected in sequence. The outlet of the gas-liquid separator is connected to the inlet of the compressor. The condenser is provided with a first inlet for introducing first ambient air. The condenser is connected to the drying chamber through a heating pipe. The first ambient air heated by the condenser is introduced into the drying chamber through the heating pipe. The evaporator is provided with a second air inlet for introducing second ambient air. The evaporator is connected to the cooling chamber through a cooling pipe. The second ambient air, cooled by the evaporator, is introduced into the cooling chamber through the cooling pipe. The heating and cooling supply system also includes a controller. Variable frequency fans are installed on the heating pipe and the cooling pipe respectively. Flow sensors and temperature and humidity sensors are installed on the air outlets of the heating pipe and the cooling pipe. Each flow sensor, each temperature and humidity sensor, and each variable frequency fan inverter are connected to the controller via signal connection.

2. The dual-output (cold and hot) temperature-controlled heat pump device according to claim 1, characterized in that: The drying chamber includes a primary drying chamber and a secondary drying chamber; the condenser includes a first sub-condenser and a second sub-condenser arranged in series and isolated from each other, and both the first sub-condenser and the second sub-condenser are provided with the first air inlet; the heating pipe includes a first heating pipe and a second heating pipe, and both the first heating pipe and the second heating pipe are provided with the variable frequency fan; the first sub-condenser is connected to the primary drying chamber through the first heating pipe, and the second sub-condenser is connected to the secondary drying chamber through the second heating pipe. The second sub-condenser is equipped with multiple electric heating tubes for heating the first ambient air, and the controller can control the opening and closing of any of the electric heating tubes.

3. The dual-output (cold and hot) temperature-controlled heat pump device according to claim 1 or 2, characterized in that: Each of the first air inlets is equipped with a filter screen.

4. The dual-output (cold and hot) temperature-controlled heat pump device according to claim 2, characterized in that: The condenser includes a first housing, and the first sub-condenser and the second sub-condenser are both disposed inside the first housing. A first partition is disposed inside the first housing, and the first sub-condenser and the second sub-condenser are separated by the first partition.

5. The dual-output (cold and hot) temperature-controlled heat pump device according to any one of claims 2-4, characterized in that: The cooling chamber includes a primary cooling chamber and a secondary cooling chamber. The evaporator includes a first sub-evaporator and a second sub-evaporator arranged in series and isolated from each other. The first sub-evaporator is closer to the gas-liquid separator than the second sub-evaporator. Both the first and second sub-evaporators are provided with a second air inlet. The cooling pipe includes a first cooling pipe and a second cooling pipe. Both the first cooling pipe and the second cooling pipe are provided with the variable frequency fan. The first sub-evaporator is connected to the primary cooling chamber through the first cooling pipe, and the second sub-evaporator is connected to the secondary cooling chamber through the second cooling pipe.

6. The dual-output (cold and hot) temperature-controlled heat pump device according to claim 5, characterized in that: Each of the second air inlets is equipped with a filter screen.

7. The dual-output (cold and hot) temperature-controlled heat pump device according to claim 5, characterized in that: The evaporator includes a second housing, and both the first sub-evaporator and the second sub-evaporator are disposed within the second housing. A second partition is disposed within the second housing, and the first sub-evaporator and the second sub-evaporator are separated by the second partition.

8. A control method for a dual-output (cold and hot) temperature-controlled heat pump device according to any one of claims 5-7, characterized in that: The heat flow rate of the air outlet of the first sub-condenser is the first heat flow rate, and the variable frequency fan on the first heating pipe is the first variable frequency fan. The controller calculates the first outlet heat flow rate based on the current temperature of the outlet of the first sub-condenser, the ambient temperature, and the current air mass flow rate of the first variable frequency fan. The controller also calculates the required air mass flow rate of the first variable frequency fan based on the first outlet heat flow rate, the ambient temperature, and the required drying temperature of the first-stage drying chamber. Finally, the controller controls the first variable frequency fan to achieve the required air mass flow rate. The heat flow rate of the air outlet of the second sub-condenser is the second air outlet heat flow rate, and the variable frequency fan on the second heating pipe is the second variable frequency fan; The controller calculates the second outlet heat flow rate based on the current temperature of the outlet of the second sub-condenser, the ambient temperature, and the current air mass flow rate of the second variable frequency fan. The controller also calculates the required air mass flow rate of the second variable frequency fan based on the second outlet heat flow rate, the ambient temperature, and the required drying temperature of the secondary drying chamber. Finally, the controller controls the second variable frequency fan to achieve the required air mass flow rate. The cold air flow rate at the outlet of the first sub-evaporator is the first cold air flow rate, and the variable frequency fan on the first heating pipe is the third variable frequency fan. The controller calculates the first outlet cooling flow rate based on the current temperature of the outlet of the first sub-evaporator, the ambient temperature, and the current air mass flow rate of the third variable frequency fan. The controller also calculates the required air mass flow rate of the third variable frequency fan based on the first outlet cooling flow rate, the ambient temperature, and the required cooling temperature of the first-stage cooling chamber. Finally, the controller controls the third variable frequency fan to achieve the required air mass flow rate. The cold air flow rate at the outlet of the second sub-evaporator is the second cold air flow rate, and the variable frequency fan on the second heating pipe is the fourth variable frequency fan; The controller calculates the second outlet cooling flow rate based on the current temperature of the outlet of the second sub-evaporator, the ambient temperature, and the current air mass flow rate of the fourth variable frequency fan. The controller also calculates the required air mass flow rate of the fourth variable frequency fan based on the second outlet cooling flow rate, the ambient temperature, and the required cooling temperature of the secondary cooling chamber. Finally, the controller controls the fourth variable frequency fan to achieve the required air mass flow rate.

9. The control method according to claim 8, characterized in that: The calculation process for the required air mass flow rate of the first variable frequency fan includes the following steps: S1. Calculate the first outlet air heat flow rate Q. 热 The calculation formula is as follows: Q 热 =q0*C 空气 (T1-T0) (1) In formula (1): Q 热 q0 is the first outlet air heat flow rate, kJ / h; q0 is the current air mass flow rate delivered by the first variable frequency fan, in kg / h; C 空气 T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the outlet temperature of the first condenser, in ℃; T3 is the ambient temperature, in ℃. S2. Based on the required drying temperature T2 of the primary drying chamber, calculate the required air mass flow rate q1 of the first variable frequency fan. The calculation formula is as follows: In formula (2): Q 热 q1 represents the total heat flow rate of the hot air, expressed in kJ / h; q1 represents the required air mass flow rate of the first variable frequency fan, expressed in kg / h; C 空气 T1 is the specific heat capacity of air, in kJ / (kg*℃); T2 is the required drying temperature of the primary drying chamber, in ℃; T0 is the ambient temperature, in ℃.

Images