A multi-connected heat pump drying unit

Abstract

The present invention relates to a multi-connected heat pump drying unit, comprising: a plurality of indoor units, which are respectively configured to be connected to a plurality of drying chambers; a plurality of circulating fans, which are respectively configured to be used for a plurality of indoor units, and are used to drive the airflow passing through the indoor units to be introduced into the drying chamber by the circulating fans; an outdoor unit, which is configured to be connected to each indoor unit through a refrigerant pipeline; a processing unit, which is configured to obtain the output frequency of the heat pump compressor in the outdoor unit according to a preset calculation rule based on the number of indoor units turned on in each turned-on state, the number of horses of each turned-on indoor unit, the correction coefficient of the dry-bulb temperature difference in the drying chamber corresponding to each turned-on indoor unit, the windshield correction coefficient of the circulating fan corresponding to each turned-on indoor unit, the outdoor temperature correction coefficient, and the exhaust pressure correction coefficient of the heat pump compressor; and control the heat pump compressor to operate according to the output frequency. The present invention helps to achieve a dynamic balance between the output of the heat pump compressor and the needs of multiple drying chambers.

Description

Technical Field

[0001] The invention relates to the technical field of air source heat pump drying, and in particular to a multi-connected heat pump drying unit. Background Art

[0002] Heat pump drying units can be used for drying and dehydrating food, medicinal materials, wood, agricultural and sideline products, industrial products, etc. Specifically, the objects to be dried are placed in a drying room, and hot air is transported into the drying room through the heat pump drying unit to remove moisture from the objects to be dried, thereby achieving the purpose of drying.

[0003] For specific applications, see Figure 1 and Figure 2 The most common one is the ordinary heat pump drying unit, which is configured with one outdoor unit and one indoor unit. One ordinary heat pump drying unit is only used for drying in one drying room. For a group of drying rooms in a row, if ordinary heat pump drying units are used, the number of ordinary heat pump drying units required is equal to the number of drying rooms. Figure 2 A1 to A6 represent indoor units, and B1 to B6 represent outdoor units. Obviously, the outdoor units configured in each common heat pump drying unit will increase the purchase cost and land cost. The above problems can be better solved by using multi-connected heat pump drying units. Figure 3 The multi-connected heat pump drying unit is configured with one outdoor unit and multiple indoor units ( Figure 3 A1 to A6 represent indoor units respectively), each indoor unit acts on one drying room, so that one outdoor unit can drive multiple indoor units to dry multiple drying rooms in the drying room group.

[0004] Considering the comprehensive cost, in the case of drying room groups, the use of multi-split heat pump drying units is a better choice. However, it should be considered that when the multi-split heat pump drying unit is applied to the drying room group, it is difficult for the user to observe the status of each drying room at the same time. After the user adjusts the indoor unit of a drying room, it may cause a situation where one hair moves the whole body, which will affect other drying rooms, but the user cannot know it in time. Therefore, when the multi-split heat pump drying unit is applied to the drying room group, the automatic control of the multi-split heat pump drying unit is the preferred choice. Similarly, in the automatic control of the multi-split heat pump drying unit, the above problems should also be considered. Summary of the invention

[0005] The present invention provides a multi-connected heat pump drying unit, which is helpful to achieve a dynamic balance between the output of a heat pump compressor and the requirements of multiple drying chambers.

[0006] The present application provides a multi-connected heat pump drying unit, comprising:

[0007] A plurality of indoor units, each of which is configured to communicate with a plurality of drying chambers;

[0008] A plurality of circulation fans, which are respectively configured for a plurality of indoor units, and are used to drive the airflow passing through the indoor units to be introduced into the drying chamber by the circulation fans;

[0009] an outdoor unit, which is configured to be connected to each indoor unit through a refrigerant pipeline;

[0010] A processing unit, configured to obtain the output frequency of the heat pump compressor in the outdoor unit according to a preset calculation rule based on the number of indoor units turned on in each turned-on state, the number of horses of each turned-on indoor unit, the correction coefficient of the indoor dry-bulb temperature difference of the drying room corresponding to each turned-on indoor unit, the windshield correction coefficient of the circulation fan corresponding to each turned-on indoor unit, the outdoor temperature correction coefficient, and the exhaust pressure correction coefficient of the heat pump compressor;

[0011] Controlling the heat pump compressor to operate according to the output frequency;

[0012] Among them, the difference between the dry-bulb temperature in the drying chamber and the set dry-bulb temperature is the dry-bulb temperature difference.

[0013] The output frequency of the compressor is determined based on the number and horsepower of each indoor unit that is turned on, the dry-bulb temperature difference correction coefficient in the drying room, the windshield correction coefficient of the circulating fan, the outdoor ambient temperature correction coefficient and the compressor exhaust pressure correction coefficient. Since the output frequency takes into account various factors that affect the compressor frequency, controlling the operation of the heat pump compressor according to the startup frequency helps to achieve a dynamic balance between the output of the heat pump compressor and the needs of multiple drying rooms.

[0014] In some embodiments of the present application, the operation of the indoor unit is controlled by the dry-bulb temperature control accuracy, specifically:

[0015] When the dry-bulb temperature difference in the drying room connected to the indoor unit reaches below a first preset temperature threshold, the indoor unit temperature control is turned on, and when the dry-bulb temperature difference reaches above a second preset temperature threshold, the indoor unit temperature control is turned off;

[0016] Wherein, the first preset temperature threshold is lower than the second preset temperature threshold.

[0017] In some embodiments of the present application, during the operation of the heat pump drying unit, the operating conditions of the indoor units affect the output frequency of the heat pump compressor. Therefore, based on the operating conditions of each indoor unit, the output frequency is adjusted.

[0018] In some embodiments of the present application, during the operation of the heat pump drying unit, the output frequency is adjusted based on the operating conditions of each indoor unit, including:

[0019] When the indoor unit is shut down due to temperature control, the output frequency is updated by subtracting the frequency required by the shut down indoor unit from the current output frequency;

[0020] When the indoor unit is turned on by temperature control, the output frequency is updated by adding the current output frequency to the frequency required by the indoor unit to be turned on.

[0021] The output frequency of the heat pump compressor is related to the number of powered-on indoor units. Therefore, when the number of powered-on indoor units increases, the output frequency increases, and when the number of powered-on indoor units decreases, the output frequency decreases.

[0022] In some embodiments of the present application, the frequency ΔF required by the indoor unit is obtained using the following formula:

[0023] △F= KT*Kpd*Khp(k)*Kfan(k)*Kc(k);

[0024] Wherein KT is the outdoor temperature correction coefficient, Kpd is the exhaust pressure correction coefficient, Khp (k) is the horsepower of the indoor unit, Kc (k) is the indoor dry-bulb temperature difference correction coefficient corresponding to the indoor drying unit, Kfan (k) is the windshield correction coefficient of the circulation fan corresponding to the indoor unit, and k is the serial number of the indoor unit.

[0025] In some embodiments of the present application, the preset calculation rule is the following formula:

[0026] Output frequency ;

[0027] Wherein, k is the serial number of the indoor unit to be powered on.

[0028] In some embodiments of the present application, during the operation of the heat pump drying unit, the output frequency is adjusted based on the operating conditions of each indoor unit, including:

[0029] When the operating conditions of each indoor unit are all normal, adjusting the output frequency in real time based on the exhaust pressure difference of the heat pump compressor;

[0030] The exhaust pressure difference is equal to the difference between the exhaust pressure and the target exhaust pressure.

[0031] In some embodiments of the present application, the output frequency is adjusted in real time based on the exhaust pressure difference of the heat pump compressor, specifically:

[0032] cyclically acquiring the exhaust pressure, increasing the output frequency when the exhaust pressure difference reaches below a first preset pressure threshold, and decreasing the output frequency when the exhaust pressure difference reaches above a second preset pressure threshold;

[0033] Wherein, the first preset pressure threshold is smaller than the second preset pressure threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The schematic diagram of the structure of the existing multi-connected heat pump drying unit is shown;

[0035] Figure 2 The schematic diagram of the structure of the indoor unit in the existing multi-split heat pump dryer unit is shown;

[0036] Figure 3 A schematic structural diagram of a multi-connected heat pump drying unit according to some embodiments is shown;

[0037] Figure 4 A schematic diagram showing a method for determining the output power of a heat pump compressor of a multi-connected heat pump drying unit according to some embodiments is shown;

[0038] Figure 5 A control flow chart of temperature-controlled startup and temperature-controlled shutdown of an indoor unit in a multi-connected heat pump drying unit according to some embodiments is shown;

[0039] Figure 6 A schematic diagram showing a method of determining the output frequency of a heat pump compressor when a new indoor unit of a multi-connected heat pump drying unit is turned on with temperature control in operation according to some embodiments;

[0040] Figure 7 A schematic diagram showing a method of determining the output frequency of a heat pump compressor when a new indoor unit of a multi-connected heat pump drying unit is temperature-controlled and shut down during operation according to some embodiments;

[0041] Figure 8 A schematic diagram showing a method of determining the output frequency of a heat pump compressor of a multi-connected heat pump drying unit when each indoor unit operates normally according to some embodiments. Implementation

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0044] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0047] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0048] The heat pump drying method is used to dry the items (such as tea leaves and chrysanthemums) in the drying room. The present application relates to a multi-connected heat pump drying unit. Figure 3 The multi-split heat pump drying unit includes multiple indoor units, multiple circulation fans, an outdoor unit and a processing unit.

[0049] One circulation fan corresponds to one indoor unit and one drying room respectively.

[0050] A plurality of indoor units and an outdoor unit are connected via a refrigerant pipeline, and a processing unit is used to determine an output frequency F of a heat compressor in the outdoor unit.

[0051] See also Figure 2 An air inlet and an air outlet are provided on the side wall of the heating chamber corresponding to the drying chamber, and the air inlet and the air outlet are respectively connected to the drying chamber.

[0052] The corresponding circulating fan is placed in the heating chamber. The circulating fan is arranged close to the air outlet and is used to introduce the air flow in the heating chamber into the inlet of the drying chamber through the air outlet by the circulating fan.

[0053] The air inlet of the heating chamber returns the air to the outlet of the drying chamber.

[0054] The indoor unit is arranged in the heating chamber and is located below the circulating fan. The airflow flowing in through the air inlet of the heating chamber passes through the indoor unit and is driven by the circulating fan to be sent into the drying chamber through the air outlet.

[0055] The air inlet is arranged below the side wall of the heating chamber, and the air outlet is arranged above the side wall of the heating chamber, so as to form a hot air flow from top to bottom in the drying chamber.

[0056] See also Figure 3 , an outdoor unit and multiple indoor units are connected through refrigerant pipelines to form a heat pump circulation system.

[0057] The outdoor unit includes a heat pump compressor, an outdoor heat exchanger and an outdoor fan, the indoor unit includes an indoor heat exchanger and an indoor fan, and a throttling device (such as a capillary tube or an electronic expansion valve) may be provided in the indoor unit or the outdoor unit.

[0058] The heat pump cycle is performed by using a heat pump compressor, a condenser, an expansion valve, and an evaporator.

[0059] In the present application, a heat pump heating cycle of a multi-connected heat pump drying unit is mainly used to dry the items to be dried in the drying room.

[0060] The low-temperature and low-pressure refrigerant enters the compressor, which compresses it into high-temperature and high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0061] The working principle of the heat pump heating cycle is as follows: the refrigerant is pressurized by the heat pump compressor to become a high-temperature and high-pressure gas, which enters the indoor heat exchanger (the condenser at this time), condenses and liquefies to release heat and becomes a liquid. The liquid refrigerant is depressurized by the throttling device and enters the outdoor heat exchanger (the evaporator at this time), evaporates and vaporizes to absorb heat and becomes a low-temperature and low-pressure gaseous refrigerant. After passing through the gas-liquid separator, it flows back to the compressor for compression and enters the next cycle.

[0062] like Figure 3 Six drying chambers (drying chamber 1 to drying chamber 6) are shown. In actual use, the number of drying chambers can be freely set and the number of drying chambers opened for use can also be freely set.

[0063] The application description is given by taking tobacco as the object to be dried. In actual application, when the amount of tobacco is large, all the drying rooms are used, and accordingly, all the indoor units of the multi-split heat pump drying unit are turned on, while when the amount of tobacco is small, some of the drying rooms are used, and accordingly, some of the indoor units of the multi-split heat pump drying unit are turned on.

[0064] As follows, the output frequency of the heat pump compressor in the outdoor unit is determined when the unit is just started up to meet the dynamic demand of multiple drying rooms.

[0065] See also Figure 4 , which shows a schematic diagram for determining the output frequency F of the heat pump compressor in the outdoor unit.

[0066] S1: Obtain the number m of indoor units that need to be turned on and the horsepower Khp(k) of each turned-on indoor unit.

[0067] Wherein, k is the serial number of the powered-on indoor unit, and k≤m, m≥1 and is a natural number.

[0068] According to the drying room to be used, turn on the indoor unit of the corresponding drying room.

[0069] As mentioned above, see Figure 3 If drying room 1 and drying room 2 are used, the indoor unit A1 corresponding to drying room 1 and the indoor unit A2 corresponding to drying room 2 need to be turned on. At this time, the number m is 2.

[0070] The capacities of multiple indoor units in a multi-split heat pump drying unit are known in advance, so the capacities of the indoor units that are turned on are available.

[0071] When the indoor unit A1 as described above is turned on, its corresponding horsepower Khp(1) is obtained, and when the indoor unit A2 as described above is turned on, its corresponding horsepower Khp(2) is obtained.

[0072] S2: Get the drying chamber dry bulb temperature Tdry and set dry bulb temperature Tdry_set.

[0073] If multiple indoor units are turned on and running, it is necessary to obtain the dry-bulb temperature and set dry-bulb temperature of the drying chamber corresponding to each indoor unit.

[0074] In practical applications, a multi-split heat pump dryer can be equipped with a temperature detection sensor in each drying room, and the dry-bulb temperature Tdry in the corresponding drying room can be obtained according to the indoor unit that is turned on and running.

[0075] The dry-bulb temperature Tdry and the set dry-bulb temperature Tdry_set of each drying chamber are obtained in order to obtain the dry-bulb temperature difference correction coefficient Kc(k) in each drying chamber.

[0076] If both indoor unit A1 and indoor unit A2 are turned on, the dry-bulb temperature difference correction coefficient of drying chamber 1 corresponding to indoor unit A1 is Kc(1), and the dry-bulb temperature difference correction coefficient of drying chamber 2 corresponding to indoor unit A2 is Kc(2).

[0077] It should be noted that the dry-bulb temperature difference correction coefficient Kc (k) of each drying chamber is a coefficient adjusted during the experiment when drying the objects to be dried in the drying chamber.

[0078] A data table between the dry-bulb temperature difference △Tdry and the dry-bulb temperature difference correction coefficient Kc(k) may be established in advance.

[0079] After actually obtaining the dry-bulb temperature difference △Tdry, the corresponding dry-bulb temperature difference correction coefficient Kc(k) can be obtained by querying the data table.

[0080] The dry-bulb temperature difference ΔTdry is the difference between the dry-bulb temperature Tdry and the set dry-bulb temperature Tdry_set.

[0081] The lower the dry-bulb temperature Tdry is than the set dry-bulb temperature Tdry_set, the larger Kc(k) is.

[0082] S3: Obtain the gear position of the circulation fan corresponding to the drying chamber.

[0083] If multiple indoor units are turned on and running, it is necessary to obtain the gear position of the circulation fan corresponding to each indoor unit.

[0084] The gear position of the circulation fan can be N (N≥2).

[0085] For example, the circulating fan has high and low gears.

[0086] The purpose of obtaining the gear position of each circulation fan is to obtain the wind gear correction coefficient Kfan(k) of each circulation fan.

[0087] If both indoor unit A1 and indoor unit A2 are turned on, the wind speed correction coefficient of the circulation fan corresponding to indoor unit A1 is Kfan(1), and the wind speed correction coefficient of the circulation fan corresponding to indoor unit A2 is Kfan(2).

[0088] It should be noted that the windage correction coefficient Kfan (k) of each circulating fan is a coefficient adjusted during the experiment when drying the objects to be dried in the drying room.

[0089] A data table between the gear position of the circulation fan and the wind gear correction coefficient Kfan (k) can be established in advance.

[0090] After actually obtaining the gear position of the circulation fan, the corresponding wind gear correction coefficient Kfan(k) can be obtained by querying the data table.

[0091] S4: Obtain the outdoor ambient temperature Ttep.

[0092] The purpose of obtaining the outdoor ambient temperature T is to obtain the outdoor temperature correction coefficient KT.

[0093] It should be noted that the outdoor temperature correction coefficient KT is also a coefficient adjusted during the experiment when drying the objects to be dried in the drying room.

[0094] A data table between the outdoor ambient temperature T and the outdoor temperature correction coefficient KT may be established in advance.

[0095] After actually obtaining the outdoor ambient temperature T, the corresponding outdoor temperature correction coefficient KT can be obtained by querying the data table.

[0096] The lower the outdoor ambient temperature T, the greater the outdoor temperature correction coefficient KT.

[0097] S5: Obtain the exhaust pressure of the heat pump compressor.

[0098] The exhaust pressure Pd of the heat pump compressor is obtained in order to obtain the exhaust pressure correction coefficient Kpd.

[0099] It should be noted that the exhaust pressure correction coefficient Kpd is also a coefficient adjusted during the experiment when drying the objects to be dried in the drying room.

[0100] The exhaust pressure Pd may be established in advance in order to obtain the exhaust pressure correction coefficient Kpd.

[0101] It should be noted that there is a data table between the exhaust pressure Pd and the exhaust pressure correction coefficient Kpd.

[0102] After the exhaust pressure Pd is actually obtained, the corresponding exhaust pressure correction coefficient Kpd can be obtained by querying the data table.

[0103] The greater the exhaust pressure Pd, the smaller the exhaust pressure correction coefficient Kpd.

[0104] There is no sequential relationship between S1 to S5 as described above, and the above sequential relationship is only an example.

[0105] S6: Obtain the output frequency F of the heat pump compressor.

[0106] Based on the data obtained in S1 to S5, including the number m of each turned-on indoor unit, the horsepower Khp(k) of each turned-on indoor unit, the dry-bulb temperature correction coefficient Kc(k) of the drying room corresponding to each turned-on indoor unit, the windshield correction coefficient Kfan(k) of the circulation fan corresponding to each turned-on indoor unit, the outdoor temperature correction coefficient KT and the exhaust pressure correction coefficient Kpd, the output frequency F of the heat pump compressor is obtained according to the preset calculation rules.

[0107] The output frequency F is used as the operating frequency of the heat pump compressor that has just started running.

[0108] In this application, the preset calculation rule is selected as the following calculation formula:

[0109] .

[0110] If indoor unit A1 and indoor unit A2 are turned on and running, the output frequency F is calculated as follows:

[0111] F=KT*Kpd*[Khp(1)* Kfan(1)* Kc(1)+ Khp(2)* Kfan(2)* Kc(2)].

[0112] If indoor units A1, A2 and A3 are turned on and running, the output frequency F is calculated as follows:

[0113] F=KT*Kpd*[Khp(1)* Kfan(1)* Kc(1)+ Khp(2)* Kfan(2)* Kc(2)+ Khp(3)*Kfan(3)* Kc(3)].

[0114] S7: Control the heat pump compressor to start running at the output frequency F.

[0115] The output frequency F of the heat pump compressor when it is turned on is related to each indoor unit, circulating fan, outdoor ambient temperature and compressor exhaust pressure. Comprehensive consideration of the factors affecting each drying room will help make the output of the heat pump compressor fully match the drying characteristics of the objects to be dried, which in turn helps to ensure the drying quality of each drying room.

[0116] When the multi-split heat pump drying unit is turned on and enters operation, if there is a load fluctuation, such as the shutdown of some indoor units or the startup of new indoor units, the output frequency F of the heat pump compressor will be affected. At this time, the output frequency of the heat pump compressor should be adjusted in time to ensure that the output frequency of the heat pump compressor meets the dynamic needs of multiple drying rooms.

[0117] The indoor unit temperature control shutdown or temperature control startup is determined based on the dry-bulb temperature difference in the drying room.

[0118] When the dry-bulb temperature difference △Tdry in the drying room reaches below a first preset temperature threshold, the indoor unit temperature control is turned on, and when the dry-bulb temperature difference △Tdry reaches above a second preset temperature threshold, the indoor unit temperature control is turned off.

[0119] The first preset temperature threshold is smaller than the second preset temperature threshold.

[0120] The first preset temperature threshold may be set to -1°C, and the second preset temperature threshold may be set to 1°C.

[0121] See also Figure 5 During the operation of the multi-connected heat pump drying unit, the dry bulb temperature Tdry in each drying chamber is detected in real time.

[0122] Get the dry-bulb temperature Tdry and the set dry-bulb temperature Tdry_set, and calculate the dry-bulb temperature difference △Tdry.

[0123] When the dry-bulb temperature difference △Tdry>-1℃, the temperature control of the indoor unit of the corresponding drying room will be shut down.

[0124] When the dry-bulb temperature difference △Tdry≤-1℃, the temperature control of the indoor unit of the corresponding drying room is turned on, and the temperature control is stopped when △Tdry≥1℃.

[0125] In this way, the dry bulb temperature accuracy is controlled within ±1°C.

[0126] As described above, when some indoor units are shut down or new indoor units are started up, the output frequency of the heat pump compressor needs to be adjusted in time.

[0127] Therefore, it is necessary to adjust the output frequency of the heat pump compressor based on the operating conditions of the indoor unit.

[0128] See also Figure 6 , which shows a schematic diagram of adjusting the output frequency when a new indoor unit temperature control is turned on.

[0129] As described above, when it is necessary to restart a certain indoor unit, it is necessary to obtain the horsepower Khp(m+1) corresponding to the newly started indoor unit, the dry-bulb temperature correction coefficient Kc(m+1) corresponding to the drying room of the indoor unit, the windshield correction coefficient Kfan(m+1) corresponding to the circulation fan of the indoor unit, the outdoor temperature correction coefficient KT and the exhaust pressure correction coefficient Kpd according to S1 to S5 as described above.

[0130] The frequency required by the indoor unit △F = KT*Kpd*Khp(m+1)*Kfan(m+1)*Kc(m+1).

[0131] Update the output frequency to F+△F.

[0132] In this way, the heat pump compressor is controlled to operate at the updated F.

[0133] If there are some newly started indoor units, the frequencies required by these indoor units need to be calculated and processed, and then the output frequency F is updated.

[0134] See also Figure 7 , which shows a schematic diagram of adjusting the output frequency when the indoor unit temperature control shutdown occurs.

[0135] As described above, when the indoor unit is turned on, the required frequency ΔF needs to be calculated.

[0136] Therefore, when a temperature control of a certain indoor unit is stopped, its required frequency △F needs to be subtracted from the current output frequency F and the output frequency needs to be updated.

[0137] The updated output frequency is F-△F.

[0138] In this way, the heat pump compressor is controlled to operate at the updated F.

[0139] If some of the indoor units are turned on and the temperature control is turned off, it is necessary to deduct the frequencies required by these indoor units and then update the output frequency F.

[0140] In normal operation, since there is no load fluctuation, for the dynamic balance between the heat pump compressor and each indoor unit, in this application, the exhaust pressure difference of the heat pump compressor is used to adjust the output frequency.

[0141] The exhaust pressure difference is the difference between the exhaust pressure Pd and the target exhaust pressure Pdo.

[0142] It should be noted that the normal operation here means that within a period of time (for example, 30 seconds), there is no new temperature-controlled indoor unit turned on, and there is no temperature-controlled shutdown of the turned-on indoor unit (that is, all turned-on indoor units operate normally).

[0143] See also Figure 8, describing the schematic diagram of adjusting the output frequency based on the exhaust pressure difference.

[0144] (1) Obtain the exhaust pressure of the heat pump compressor.

[0145] (2) Calculate the exhaust pressure difference: that is, the exhaust pressure difference is equal to Pd-Pdo.

[0146] (3) The cycle determines the number of adjustment steps △F of the output frequency based on the exhaust temperature difference.

[0147] The cycle time is the period T, for example 30 seconds.

[0148] The number of adjustment steps △F increases as the exhaust pressure difference increases.

[0149] The adjustment step number ΔF includes a step number value and a sign, and the sign includes a positive sign for indicating an increase in frequency and a negative sign for indicating a decrease in frequency.

[0150] When the exhaust pressure difference reaches below the first preset pressure threshold (ie, -ΔPd), the current output frequency increases by the step value of the adjustment step ΔF.

[0151] When the exhaust pressure difference reaches below the second preset pressure threshold (ie, ΔPd) and above the first preset pressure threshold, the current output frequency F is maintained, ie, ΔF=0.

[0152] When the exhaust pressure difference reaches above the second preset pressure threshold, the current output frequency is reduced by the step value of the adjustment step ΔF.

[0153] The first preset pressure threshold is greater than the second preset pressure threshold.

[0154] The first preset pressure threshold may be selected as -△Pd℃, the second preset pressure threshold may be selected as △Pd, and △Pd may be selected as a value between 0.1 and 0.5.

[0155] In the present application, the number of adjustment steps ΔF is determined by the value range of the exhaust pressure difference in each cycle.

[0156] The range of exhaust pressure difference can be divided into Pd-Pdo<-△Pd, -△Pd≤Pd-Pdo≤△Pd and △Pd<Pd-Pdo.

[0157] See also Figure 8 , when Pd-Pdo<-△Pd, the adjustment step number △F=3;

[0158] When -△Pd≤Pd-Pdo≤△Pd, the adjustment step number △F=0;

[0159] When △Pd<Pd-Pdo, the adjustment step number △F=-3.

[0160] (4) After calculating △F in each cycle, the output frequency is updated, that is, F=F+△F.

[0161] After that, enter the next loop and return to (1).

[0162] It should be noted that when △F is a negative value, it indicates that the current output frequency is reduced, and when △F is a positive value, it indicates that the current output frequency is increased.

[0163] In this way, the exhaust pressure accuracy of the heat pump compressor can be controlled within ±△Pd when the load does not fluctuate, ensuring that the compressor output frequency meets the dynamic requirements of multiple drying rooms.

[0164] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0165] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A multi-connected heat pump drying unit, characterized in that: include: A plurality of indoor units, each of which is configured to communicate with a plurality of drying chambers; A plurality of circulation fans, which are respectively configured for a plurality of indoor units, and are used to drive the airflow passing through the indoor units to be introduced into the drying chamber by the circulation fans; an outdoor unit, which is configured to be connected to each indoor unit through a refrigerant pipeline; The processing unit is configured to calculate the number of indoor units powered on in each power-on state and the number of matches of each powered-on indoor unit. Khp ( k ), correction coefficient of indoor dry-bulb temperature difference of each indoor unit Kc(k) , the windshield correction coefficient of the circulation fan corresponding to each indoor unit Kfan(k) , Outdoor temperature correction factor KT , and the exhaust pressure correction factor of the heat pump compressor KpD ,according to The output frequency F of the heat pump compressor in the outdoor unit is obtained, where: k It is the serial number of the indoor unit to be powered on; Controlling the heat pump compressor to operate according to the output frequency F; Among them, the difference between the dry bulb temperature in the drying room and the set dry bulb temperature is the dry bulb temperature difference. The dry bulb temperature difference correction coefficient, windshield correction coefficient, outdoor temperature correction coefficient and exhaust pressure correction coefficient are all coefficients adjusted in the experiment when drying the objects to be dried in the drying room. The lower the dry-bulb temperature is than the set dry-bulb temperature, the larger Kc(k) is, the lower the outdoor ambient temperature is, the larger the outdoor temperature correction coefficient KT is, the greater the exhaust pressure is, and the smaller the exhaust pressure correction coefficient Kpd is.

2. The multi-connected heat pump drying unit according to claim 1, characterized in that: The indoor unit is started and operated based on the dry-bulb temperature difference in the drying chamber, specifically: When the dry-bulb temperature difference in the drying room connected to the indoor unit reaches below a first preset temperature threshold, the indoor unit temperature control is turned on, and when the dry-bulb temperature difference reaches above a second preset temperature threshold, the indoor unit temperature control is turned off; Wherein, the first preset temperature threshold is lower than the second preset temperature threshold.

3. The multi-connected heat pump drying unit according to claim 1, characterized in that: During the operation of the heat pump drying unit, the output frequency is adjusted based on the operating conditions of each indoor unit.

4. The multi-connected heat pump drying unit according to claim 3, characterized in that: During the operation of the heat pump drying unit, the output frequency is adjusted based on the operating conditions of each indoor unit, including: When the indoor unit is shut down due to temperature control, the output frequency is updated by subtracting the frequency required by the shut down indoor unit from the current output frequency; When the indoor unit is turned on by temperature control, the output frequency is updated by adding the frequency required by the indoor unit to be turned on to the current output frequency.

5. The multi-connected heat pump drying unit according to claim 4, characterized in that: The frequency ΔF required by the indoor unit is obtained using the following formula: △F= KT*Kpd*Khp(k)*Kfan(k)*Kc(k); Wherein KT is the outdoor temperature correction coefficient, Kpd is the exhaust pressure correction coefficient, Khp (k) is the horsepower of the indoor unit, Kc (k) is the indoor dry-bulb temperature difference correction coefficient corresponding to the indoor unit, Kfan (k) is the windshield correction coefficient of the circulation fan corresponding to the indoor unit, and k is the serial number of the indoor unit.

6. The multi-connected heat pump drying unit according to claim 3, characterized in that: During the operation of the heat pump drying unit, the output frequency is adjusted based on the operating conditions of each indoor unit, including: When the operating conditions of each indoor unit are all normal, adjusting the output frequency in real time based on the exhaust pressure difference of the heat pump compressor; The exhaust pressure difference is equal to the difference between the exhaust pressure and the target exhaust pressure.

7. The multi-connected heat pump drying unit according to claim 6, characterized in that: Based on the exhaust pressure difference of the heat pump compressor, the output frequency is adjusted in real time, specifically: cyclically acquiring the exhaust pressure, increasing the output frequency when the exhaust pressure difference reaches below a first preset pressure threshold, and decreasing the output frequency when the exhaust pressure difference reaches above a second preset pressure threshold; Wherein, the first preset pressure threshold is smaller than the second preset pressure threshold.

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