Refrigerating unit and control method thereof

Abstract

The invention provides a refrigerating unit and a control method thereof, the refrigerating unit comprises a compressor, a condenser and an air cooler, the air cooler is a double-coil air cooler and comprises a refrigerating coil and a dehumidifying coil, an exhaust pipe of the compressor is divided into three branches, the three branches comprise a refrigerating exhaust pipeline, an inlet is provided with a refrigerating electromagnetic valve, and an outlet is provided with a one-way valve; wherein the condenser is connected; an inlet of the heating and dehumidifying exhaust pipeline is provided with a dehumidifying electromagnetic valve, an outlet of the heating and dehumidifying exhaust pipeline is connected to an inlet of the dehumidifying coil pipe, an outlet of the dehumidifying coil pipe is connected to an inlet of the heating and dehumidifying liquid return pipeline, and an outlet of the heating and dehumidifying liquid return pipeline is provided with a one-way valve; an inlet of the defrosting exhaust pipeline is provided with a defrosting electromagnetic valve, and an outlet is provided with a one-way valve; an outlet of the refrigeration exhaust pipeline and an outlet of the heating and dehumidifying liquid return pipeline are connected to an inlet of the liquid supply pipeline, an outlet of the liquid supply pipeline is connected to an inlet of the refrigeration coil, and an outlet of the refrigeration coil is connected to a first inlet of the compressor through an air return pipeline. According to the refrigerating unit provided by the invention, one set of refrigerating and condensing unit can meet the temperature and humidity double-index requirements, the combined operation of the refrigerating unit and a rotary dehumidifier is not needed, and the initial investment is reduced; a refrigerant defrosting method is adopted, the defects of high energy consumption and large warehouse temperature fluctuation caused by traditional electric defrosting are overcome, and energy-saving operation and low warehouse temperature fluctuation of the cold storage are achieved.

Description

Technical Field

[0001] The invention belongs to the field of refrigeration units, and in particular, relates to a refrigeration unit and a control method thereof. Background Art

[0002] The functions of refrigeration units currently on the market are mainly limited to temperature control of cold storage, ensuring that the temperature reaches the preset index and the allowable deviation range. However, for the key parameter of relative humidity of cold storage, it is difficult for refrigeration units to achieve precise control alone. Therefore, in most engineering projects, the mode of collaborative operation of refrigeration units and rotary dehumidifiers is often adopted: the refrigeration unit is responsible for meeting the temperature index requirements, while the rotary dehumidifier focuses on achieving the relative humidity index requirements, thereby ensuring that the cold storage can meet strict control standards in both temperature and humidity dimensions.

[0003] In addition, the internal unit (i.e., air cooler) in the integrated refrigeration machine generally adopts electric defrosting technology, which will cause the temperature of the cold storage to rise significantly during the defrosting process, the temperature inside the storage will fluctuate greatly, and the energy consumption of the electric defrosting process is high.

[0004] This combination not only has a large initial investment cost, but also considerable operating costs. The economic performance indicators are not ideal, and it also does not meet the green goals of energy conservation and environmental protection. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a refrigeration unit and a control method thereof.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, the present invention provides a refrigeration unit, including a compressor, a condenser and an air cooler, wherein the air cooler is a double-coil air cooler, including a refrigeration coil and a dehumidification coil, and the exhaust pipe of the compressor is divided into three branches, including:

[0008] A refrigeration exhaust pipeline, with a refrigeration solenoid valve at the inlet and a one-way valve at the outlet, wherein the condenser is connected;

[0009] A heating and dehumidification exhaust pipeline, the inlet of which is provided with a dehumidification solenoid valve, the outlet of which is connected to the inlet of the dehumidification coil, the outlet of the dehumidification coil is connected to the inlet of the heating and dehumidification return liquid pipeline, and the outlet of the heating and dehumidification return liquid pipeline is provided with a one-way valve;

[0010] The defrost exhaust pipeline has a defrost solenoid valve at the inlet and a one-way valve at the outlet;

[0011] The outlets of the refrigeration exhaust pipeline and the heating and dehumidification liquid return pipeline are respectively connected to the inlet of the liquid supply pipeline, the outlet of the liquid supply pipeline is connected to the inlet of the refrigeration coil, and the outlet of the refrigeration coil is connected to the first inlet of the compressor through the return air pipeline.

[0012] Furthermore, a liquid accumulator, a liquid supply solenoid valve, and a throttling expansion valve are sequentially arranged in the liquid supply pipeline along the direction of refrigerant flow.

[0013] Furthermore, a gas-liquid separator is provided in the air return pipeline.

[0014] Furthermore, a crankcase pressure regulating valve is provided between the outlet of the gas-liquid separator and the first inlet of the compressor.

[0015] In a second aspect, the present invention provides a control method for a refrigeration unit, which is applied to the refrigeration unit as described above, including: the operating modes of the refrigeration unit include a refrigeration mode, a heating and dehumidification mode, and a defrost mode, and the start and stop and operating mode of the refrigeration unit are determined and adjusted based on the real-time feedback input of analog quantities of temperature sensors and humidity sensors arranged in the cold storage.

[0016] Furthermore,

[0017] In the cooling mode, the cooling solenoid valve and the liquid supply solenoid valve are opened, and the dehumidification solenoid valve and the defrost solenoid valve are closed;

[0018] In the heating and dehumidification mode, the dehumidification solenoid valve and the liquid supply solenoid valve are opened, and the cooling solenoid valve and the defrost solenoid valve are closed;

[0019] In the defrost mode, the defrost solenoid valve is opened, and the refrigeration solenoid valve, the dehumidification solenoid valve and the liquid supply solenoid valve are closed.

[0020] Furthermore,

[0021] The start and stop of the refrigeration unit and the determination and adjustment of the operating mode are realized through the control of the dual indicators of temperature T and relative humidity RH;

[0022] When the startup operation condition is met, the refrigeration unit starts to operate, and the startup operation condition is that any one of the temperature parameter T and the relative humidity parameter RH exceeds the set value, that is, T>Ts or RH>RHs, where Ts is the target storage temperature setting value and RHs is the relative humidity setting value;

[0023] When the cooling mode operation condition is met, the refrigeration unit enters the cooling mode operation, and the cooling mode operation condition is that the temperature parameter T exceeds the set value, that is, T>Ts;

[0024] When the heating and dehumidification mode operation conditions are met, the refrigeration unit enters the heating and dehumidification mode operation, and the heating and dehumidification mode operation conditions are that the relative humidity parameter RH exceeds the set value, RH>RHs;

[0025] When both the cooling mode operating conditions and the heating and dehumidification mode operating conditions are met, the refrigeration unit will enter the cooling mode operation first;

[0026] When the shutdown condition is met, the refrigeration unit shuts down and enters the standby mode. The shutdown condition is that the temperature parameter T and the humidity parameter RH are both less than or equal to the set value, that is, T≤Ts and RH≤RHs.

[0027] Furthermore,

[0028] The start and stop of the refrigeration unit and the determination and adjustment of the operation mode are realized through the dead zone control of the temperature T and relative humidity RH dual indicators;

[0029] The startup operating condition is adjusted to any one of the temperature parameter T and the relative humidity parameter RH exceeding the upper limit of the dead zone, that is, T>Ts+Tx or RH>RHs+RHx, where Tx is the temperature deviation setting value and RHx is the relative humidity deviation setting value;

[0030] The cooling mode operating condition is adjusted to the temperature parameter T exceeding the upper limit of the dead zone, that is, T>Ts+Tx;

[0031] The operating conditions of the heating and dehumidification mode are adjusted to the relative humidity parameter RH exceeding the upper limit of the dead zone, that is, RH>RHs+RHx;

[0032] The shutdown condition is adjusted to that the temperature parameter T and the humidity parameter RH are both less than or equal to the lower limit of the dead zone, that is, T≤Ts-Tx and RH≤RHs-RHx.

[0033] Furthermore,

[0034] The refrigeration unit enters the defrost mode at a fixed time;

[0035] In defrost mode, when the defrost exit conditions are met, defrost ends;

[0036] A defrost exit temperature probe is provided in the refrigeration coil, and the defrost exit condition is that the temperature Tcoil measured by the defrost exit temperature probe or the defrost exit time dt reaches a preset value, that is, Tcoil≥T0 or dt≥t0, wherein T0 is the defrost exit temperature preset value, and t0 is the defrost exit time preset value.

[0037] Furthermore,

[0038] After defrosting is completed, the refrigeration unit performs the defrosting dripping procedure;

[0039] During the defrost dripping procedure, the refrigeration solenoid valve, dehumidification solenoid valve, defrost solenoid valve, and liquid supply solenoid valve are all closed, and the compressor is shut down;

[0040] After the defrost dripping program is completed, the standby program is executed.

[0041] After adopting the above technical solution, the refrigeration unit and control method thereof provided by the present invention have the following beneficial effects compared with the prior art:

[0042] 1. The refrigeration unit provided by the present invention can meet the dual index requirements of temperature and humidity with one set of refrigeration condensing unit, without the need to operate the refrigeration unit and the rotary dehumidifier together, thus reducing the initial investment;

[0043] 2. The refrigeration unit provided by the present invention adopts the refrigerant defrosting method to change the defects of high energy consumption and large storage temperature fluctuation caused by traditional electric defrosting, and realize energy-saving operation of cold storage and low storage temperature fluctuation;

[0044] 3. The refrigeration unit provided by the present invention adopts a package solution to achieve technical integration and linkage control of the external and internal machines, avoiding the incoordination problems caused by the traditional external and internal machines coming from different brands and being independently controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0046] Figure 1 It is a schematic diagram of a refrigeration unit system provided by the present invention;

[0047] Figure 2 It is a control flow chart of the refrigeration unit provided by the present invention;

[0048] Figure 3 It is a psychrometric diagram of the process of regulating the air temperature and humidity in the cold storage according to the present invention.

[0049] In the figure: 10-compressor; 20-condenser; 30-refrigeration solenoid valve; 40-dehumidification solenoid valve; 50-defrost solenoid valve; 60-crankcase pressure regulating valve; 70-first one-way valve; 80-air cooler; 81-dehumidification coil; 82-refrigeration coil; 90-throttling expansion valve; 100-liquid supply solenoid valve; 110-liquid reservoir; 120-second one-way valve; 130-third one-way valve; 140-gas-liquid separator.

[0050] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0052] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0053] 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 an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] In addition, 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0055] [Example 1]

[0056] like Figure 1 As shown, the present invention provides a refrigeration system, which mainly includes a compressor 10, a condenser 20 and an air cooler 80, wherein the air cooler 80 is an internal unit, and the rest of the refrigeration system is an external unit. Further, the air cooler 80 is a double-coil air cooler, including a refrigeration coil 82 and a dehumidification coil 81, and the exhaust pipe of the compressor 10 is divided into three branches through a four-way joint, including a refrigeration exhaust pipeline, a heating and dehumidification exhaust pipeline, and a defrosting exhaust pipeline.

[0057] A refrigeration solenoid valve 30 is provided at the inlet of the refrigeration exhaust pipeline, and a third one-way valve 130 is provided at the outlet, wherein the condenser 20 is connected.

[0058] A dehumidification solenoid valve 40 is provided at the inlet of the heating and dehumidification exhaust pipeline, and the outlet is connected to the inlet of the dehumidification coil 81. The outlet of the dehumidification coil 81 is connected to the inlet of the heating and dehumidification return liquid pipeline. A second one-way valve 120 is provided at the outlet of the heating and dehumidification return liquid pipeline.

[0059] A defrost solenoid valve 50 is provided at the inlet of the defrost exhaust pipeline, and a first non-return valve 70 is provided at the outlet.

[0060] The outlets of the refrigeration exhaust pipeline and the heating and dehumidification liquid return pipeline are respectively connected to the inlet of the liquid supply pipeline, and the outlet of the liquid supply pipeline is connected to the inlet of the refrigeration coil 82, and the outlet of the refrigeration coil 82 is connected to the first inlet of the compressor 10 through the return air pipeline. In the liquid supply pipeline, a liquid accumulator 110, a liquid supply solenoid valve 100 and a throttling expansion valve 90 are sequentially arranged along the direction of refrigerant flow, so that the refrigeration cycle liquid refrigerant is throttled by the expansion valve 90 and supplied to the refrigeration coil 82 of the storage mechanism to perform refrigeration heat exchange and maintain the refrigeration cycle.

[0061] A gas-liquid separator 140 is provided in the return air pipeline, and a crankcase pressure regulating valve 60 is provided between the outlet of the gas-liquid separator 140 and the first inlet of the compressor 10. The gas-liquid separator 140 separates the liquid refrigerant to ensure that the gaseous refrigerant returns to the compressor 10 through the crankcase pressure regulating valve 60 to avoid damage to the compressor 10 due to liquid hammer. The crankcase pressure regulating valve 60 can avoid a short-term high load overload when the compressor 10 is restarted after defrosting, and plays a role in stable regulation.

[0062] The operating modes of the refrigeration unit include cooling mode, heating and dehumidification mode and defrost mode.

[0063] In the refrigeration mode, the refrigeration solenoid valve 30 and the liquid supply solenoid valve 100 are opened, the dehumidification solenoid valve 40 and the defrost solenoid valve 50 are closed, and the refrigerant enters the refrigeration coil 82 of the storage machine for evaporation and heat exchange after throttling through the condenser 20, the third one-way valve 130, the liquid storage 110 and the expansion valve 90, and then enters the gas-liquid separator 140, and then returns to the compressor 10 through the crankcase pressure regulating valve 60 to complete the refrigeration cycle. During this operation, the temperature of the cold storage gradually decreases, so that the temperature of the cold storage meets the index requirements.

[0064] In the heating and dehumidification mode, the dehumidification solenoid valve 40 and the liquid supply solenoid valve 100 are opened, the cooling solenoid valve 30 and the defrost solenoid valve 50 are closed, and the high-temperature exhaust gas flow direction of the compressor 10 is switched from the condenser 20 to the dehumidification coil 81 of the internal machine, and the cold air that has completed the absolute dehumidification of the dew point through the internal machine refrigeration coil 82 is heated to achieve a reduction in relative humidity RH, so that both the temperature T and the humidity RH are optimized toward the target set value. The high-temperature liquid refrigerant at the outlet of the internal machine dehumidification coil 81 flows into the liquid reservoir 110 through the second one-way valve 120, and then enters the internal machine refrigeration coil 82 through the liquid reservoir 110, the liquid supply solenoid valve 100 and the expansion valve 90 for circulation.

[0065] In the defrost mode, the defrost solenoid valve 50 is opened, the refrigeration solenoid valve 30, the dehumidification solenoid valve 40 and the liquid supply solenoid valve 100 are closed, and the high-temperature exhaust gas of the compressor 10 enters the refrigeration coil 82 in the storage machine through the defrost exhaust solenoid valve 50 and the first one-way valve 70 for defrosting. The gas-liquid two-phase refrigerant after defrosting enters the gas-liquid separator 140. After the liquid refrigerant is separated by the gas-liquid separator 140, the gaseous refrigerant returns to the compressor 10 through the crankcase pressure regulating valve 60.

[0066] In a preferred embodiment, the liquid supply pipeline is also connected to the second inlet of the compressor 10 through a liquid spray cooling branch, the inlet of the liquid spray cooling branch is connected to the upstream of the liquid supply solenoid valve 100, and a cooling solenoid valve is provided in the liquid spray cooling branch. The heat generated by the motor in the compressor 10 needs to be cooled by a certain flow of refrigerant. When the evaporation temperature of the evaporator is too low, or the evaporator load is too small, the refrigerant flow rate is too small to completely cool the motor. At this time, an external liquid spray device is required to cool the motor alone. For example, when the compressor is just started, the evaporator is too overheated and the evaporation temperature is too high, exceeding the applicable range of the compressor. At this time, the compressor is very likely to overheat or even shut down for protection, so an external liquid spray cooling device is required to cool the motor of the compressor.

[0067] [Example 2]

[0068] This embodiment describes in detail the control method of the refrigeration unit.

[0069] In the control method of the refrigeration unit, the start and stop and operation mode of the refrigeration unit are determined and adjusted according to the real-time feedback input of the analog quantity of the temperature sensor and the humidity sensor arranged in the cold storage.

[0070] Specifically, the start and stop of the refrigeration unit and the determination and adjustment of the operating mode are achieved through the control of the dual indicators of temperature T and relative humidity RH.

[0071] When the startup operation condition is met, the refrigeration unit starts to operate, and the startup operation condition is that any one of the temperature parameter T and the relative humidity parameter RH exceeds the set value, that is, T>Ts or RH>RHs, where Ts is the target storage temperature setting value and RHs is the relative humidity setting value;

[0072] When the cooling mode operation condition is met, the refrigeration unit enters the cooling mode operation, and the cooling mode operation condition is that the temperature parameter T exceeds the set value, that is, T>Ts;

[0073] When the heating and dehumidification mode operation conditions are met, the refrigeration unit enters the heating and dehumidification mode operation, and the heating and dehumidification mode operation conditions are that the relative humidity parameter RH exceeds the set value, RH>RHs;

[0074] When both the cooling mode and heating and dehumidification mode operating conditions are met, the refrigeration unit will first enter the cooling mode, and the heating and dehumidification mode will take second priority;

[0075] When the shutdown condition is met, the refrigeration unit shuts down and enters the standby mode. The shutdown condition is that the temperature parameter T and the humidity parameter RH are both less than or equal to the set value, that is, T≤Ts and RH≤RHs.

[0076] During the refrigeration process, the evaporation temperature of the refrigeration coil 82 in the storage machine is lower than the dew point temperature of the air, and the water vapor in the air is discharged through condensation, thereby reducing the absolute humidity of the air. At this time, although the temperature T of the cold storage meets the standard, the humidity RH still does not meet the index requirements, so it is necessary to switch from the refrigeration operation mode to the heating and dehumidification mode. The dehumidification solenoid valve 40 is controlled to open, and the refrigeration solenoid valve 30 is closed after a delay of 15s. The high-temperature exhaust flow of the compressor is switched from the condenser 20 to the dehumidification coil 81 in the storage machine, and the cold air that has completed the absolute dehumidification of the dew point through the refrigeration coil 82 in the storage machine is heated to reduce the relative humidity RH, so that both the temperature T and the humidity RH are optimized toward the target set value.

[0077] Usually during the initial rounds of alternating refrigeration and heating and dehumidification operations, when the heating and dehumidification operation is in operation, the relative humidity RH decreases while the storage temperature T rebounds on the basis of the set value until the storage temperature T rises above the temperature set value again (T>Ts), then the system switches to the refrigeration mode again, and switches to the next round of refrigeration operation mode and heating and dehumidification operation mode. Usually after several rounds of alternating cycles, the storage temperature T and relative humidity RH of the cold storage reach the set value requirements (T≤Ts and RH≤RHs), then the unit will shut down, and when shutting down, the refrigeration solenoid valve 30, the dehumidification solenoid valve 40, the defrost exhaust solenoid valve 50 and the liquid supply solenoid valve 100 are all closed.

[0078] The defrost mode is set to start at a fixed time, that is, the refrigeration unit enters the defrost mode at a fixed time, and in the defrost mode, when the defrost exit condition is reached, the defrost ends. A defrost exit temperature probe is provided in the refrigeration coil 82, and the defrost exit condition is that the temperature Tcoil measured by the defrost exit temperature probe or the defrost exit time dt reaches a preset value, that is, Tcoil ≥ T0 or dt ≥ t0, where T0 is the preset value of the defrost exit temperature, and t0 is the preset value of the defrost exit time.

[0079] In a preferred embodiment, T0 is 10° C. and t0 is 5 min. The values ​​of T0 and t0 can be adjusted according to actual conditions.

[0080] In a preferred embodiment, after defrosting is completed, the refrigeration unit performs a defrosting dripping program so that the defrosted water in the water tray of the refrigerator can be drained as soon as possible to avoid refrigeration again to form a new ice layer. During the defrosting dripping program, the refrigeration solenoid valve 30, the dehumidification solenoid valve 40, the defrosting solenoid valve 50, and the liquid supply solenoid valve 100 are all closed, and the compressor is stopped. In a preferred embodiment, the defrosting dripping program time is 3 minutes, which can be adjusted according to actual conditions.

[0081] After the defrosting and dripping program is completed, the standby program is executed. According to the analog feedback values ​​of the temperature sensor and humidity sensor in the cold storage, the corresponding program is calculated and determined to be executed.

[0082] [Example 3]

[0083] In order to avoid frequent switching of the refrigeration system mode, which may cause equipment damage and energy waste, this embodiment, based on the previous embodiment, realizes the determination and adjustment of the start and stop and operation mode of the refrigeration unit through the dead zone control of the dual indicators of temperature T and relative humidity RH.

[0084] The startup operating condition is adjusted to any one of the temperature parameter T and the relative humidity parameter RH exceeding the upper limit of the dead zone, that is, T>Ts+Tx or RH>RHs+RHx, where Tx is the temperature deviation setting value and RHx is the relative humidity deviation setting value;

[0085] The cooling mode operating condition is adjusted to the temperature parameter T exceeding the upper limit of the dead zone, that is, T>Ts+Tx;

[0086] The operating conditions of the heating and dehumidification mode are adjusted to the relative humidity parameter RH exceeding the upper limit of the dead zone, that is, RH>RHs+RHx;

[0087] The shutdown condition is adjusted to that the temperature parameter T and the humidity parameter RH are both less than or equal to the lower limit of the dead zone, that is, T≤Ts-Tx and RH≤RHs-RHx.

[0088] Reference Figure 2 The control flow is as follows:

[0089] After the upper computer is powered on, it determines whether the defrost conditions are met, that is, whether the current time is the defrost mode operation time (the defrost mode is set to timed start). If so, the refrigeration system runs the defrost mode. If not, it determines whether the current refrigeration mode operation conditions are met, and compares the temperature parameter T and the dead zone upper limit value, that is, whether T>Ts+Tx is satisfied. If so, the refrigeration mode is run. If not, it determines whether the current heating and dehumidification mode operation conditions are met, and compares the relative humidity parameter RH and the dead zone upper limit value, that is, whether RH>RHs+RHx is satisfied. If so, the refrigeration system runs the heating and dehumidification mode. If not, the unit stops and enters the standby state.

[0090] During the operation of the cooling mode, it is determined in real time or at regular intervals (such as every 10 seconds) whether the current operating conditions for the heating and dehumidification mode have been met. During the operation of the heating and dehumidification mode, it is determined in real time or at regular intervals (such as every 10 seconds) whether the current operating conditions for the cooling mode have been met. When the conditions for switching the operating mode are met, the operating mode is automatically switched.

[0091] During the operation of the cooling mode and the heating and dehumidification mode, it is determined whether the defrost condition is met, that is, whether the current operation time is the defrost mode. If so, it is switched to the defrost mode.

[0092] During the defrost process, when the defrost exit conditions are met, the temperature Tcoil measured by the defrost exit temperature probe or the defrost exit time dt reaches the preset value, that is, Tcoil ≥ T0 or dt ≥ t0, the defrost mode ends and the refrigeration unit executes the defrost dripping program. After the defrost dripping program ends, the unit stops and enters the standby state, cyclically judging and adjusting the operating mode that the unit should currently enter.

[0093] During the initial rounds of alternating refrigeration and heating and dehumidification operations, when the heating and dehumidification operation is in progress, the relative humidity RH decreases while the storage temperature T rebounds on the basis of the set value until the storage temperature T rises again above the upper limit of the temperature dead zone (T>Ts+Tx), then the system switches to the refrigeration mode again, and switches to the next round of refrigeration operation mode and heating and dehumidification operation mode. Usually after several rounds of alternating cycles, the storage temperature T and relative humidity RH of the cold storage reach the set value requirements (T<Ts-Tx and RH<RHs-RHx), then the unit will shut down.

[0094] Reference Figure 3 The following is an explanation of the adjustment process of air temperature and humidity in the cold storage in combination with the enthalpy-humidity diagram of the adjustment process:

[0095] For example, assume that the required storage temperature Ts of the cold storage is 10°C, and the upper and lower limits of the temperature dead zone are ±5°C (ie, Tx = 5°C); the cold storage requires relative humidity RHs = 45%, and the upper and lower limits of the humidity dead zone are ±5% (ie, RHx = 5%). The initial state point of the cold storage air temperature is A, the temperature is 20°C, the relative humidity is 60%, and the dew point temperature in this state is 15.14°C. After power-on, the unit first runs in cooling mode, and the evaporating coil temperature is 5°C lower than the dew point temperature. The unit starts the AB process of cooling and dew point absolute dehumidification until the storage temperature reaches the lower limit of the set value dead zone of 5°C, that is, state point B. At this time, the storage temperature reaches the lower limit of the set value dead zone and meets the requirements. The unit switches to the BC process of heating and dehumidification operation. The absolute humidity remains unchanged during this process, but the relative humidity gradually decreases, and the storage temperature gradually increases. When it reaches point C, the storage temperature reaches the upper limit of the temperature setting dead zone, and the unit restarts the next round of refrigeration and dew point absolute dehumidification CD process. When it reaches point D, the temperature reaches the lower limit of the setting dead zone, and the unit switches to the DE process of heating and dehumidification again. In such alternating operation (ABCDEF...), the air temperature fluctuates regularly between the upper and lower limits of the dead zone, but the humidity is always optimized to the left, and the absolute humidity and relative humidity are both decreasing. After several rounds of circulation, it reaches point F. When the temperature and humidity are both lower than the lower limit of the dead zone (T<5℃ and RH<40%), the cold storage temperature and humidity indicators meet the conditions, and the unit stops and enters the standby state.

[0096] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0097] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can also be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

Claims

1. A refrigeration unit, characterized in that: The invention comprises a compressor (10), a condenser (20) and an air cooler (80), wherein the air cooler (80) is a double-coil air cooler, comprising a refrigeration coil (82) and a dehumidification coil (81), and an exhaust pipe of the compressor (10) is divided into three branches, including: A refrigeration exhaust pipeline, the inlet of which is provided with a refrigeration solenoid valve (30), the outlet of which is provided with a third one-way valve (130), and the condenser (20) is connected thereto; A heating and dehumidification exhaust pipeline, the inlet of which is provided with a dehumidification solenoid valve (40), the outlet of which is connected to the inlet of the dehumidification coil (81), the outlet of the dehumidification coil (81) is connected to the inlet of the heating and dehumidification return liquid pipeline, and the outlet of the heating and dehumidification return liquid pipeline is provided with a second one-way valve (120); A defrost exhaust pipeline, the inlet of which is provided with a defrost solenoid valve (50), and the outlet of which is provided with a first non-return valve (70); The outlets of the refrigeration exhaust pipeline and the heating and dehumidification return liquid pipeline are respectively connected to the inlet of the liquid supply pipeline, the outlet of the liquid supply pipeline is connected to the inlet of the refrigeration coil (82), and the outlet of the refrigeration coil (82) is connected to the first inlet of the compressor (10) through the return air pipeline.

2. A refrigeration unit according to claim 1, characterized in that: A liquid accumulator (110), a liquid supply solenoid valve (100), and a throttling expansion valve (90) are sequentially arranged in the liquid supply pipeline along the direction of refrigerant flow.

3. A refrigeration unit according to claim 1, characterized in that: A gas-liquid separator (140) is provided in the gas return pipeline.

4. A refrigeration unit according to claim 3, characterized in that: A crankcase pressure regulating valve (60) is provided between the outlet of the gas-liquid separator (140) and the first inlet of the compressor (10).

5. A control method for a refrigeration unit, applied to the refrigeration unit according to any one of claims 1 to 4, characterized in that: The operating modes of the refrigeration unit include cooling mode, heating and dehumidification mode and defrost mode. The start and stop and operating mode of the refrigeration unit are determined and adjusted based on the real-time feedback input of the analog quantity of the temperature sensor and humidity sensor arranged in the cold storage.

6. The control method of the refrigeration unit according to claim 5, characterized in that: In the cooling mode, the cooling solenoid valve (30) and the liquid supply solenoid valve (100) are opened, and the dehumidification solenoid valve (40) and the defrost solenoid valve (50) are closed; In the heating and dehumidification mode, the dehumidification solenoid valve (40) and the liquid supply solenoid valve (100) are opened, and the refrigeration solenoid valve 30 and the defrost solenoid valve (50) are closed; In the defrost mode, the defrost solenoid valve (50) is opened, and the refrigeration solenoid valve (30), the dehumidification solenoid valve (40) and the liquid supply solenoid valve (100) are closed.

7. The control method of a refrigeration unit according to claim 5, characterized in that: The start and stop of the refrigeration unit and the determination and adjustment of the operating mode are realized through the control of the dual indicators of temperature T and relative humidity RH; When the startup operation condition is met, the refrigeration unit starts to operate, and the startup operation condition is that any one of the temperature parameter T and the relative humidity parameter RH exceeds the set value, that is, T>Ts or RH>RHs, where Ts is the target storage temperature setting value and RHs is the relative humidity setting value; When the cooling mode operation condition is met, the refrigeration unit enters the cooling mode operation, and the cooling mode operation condition is that the temperature parameter T exceeds the set value, that is, T>Ts; When the heating and dehumidification mode operation conditions are met, the refrigeration unit enters the heating and dehumidification mode operation, and the heating and dehumidification mode operation conditions are that the relative humidity parameter RH exceeds the set value, RH>RHs; When both the cooling mode operating conditions and the heating and dehumidification mode operating conditions are met, the refrigeration unit will enter the cooling mode operation first; When the shutdown condition is met, the refrigeration unit shuts down and enters the standby mode. The shutdown condition is that the temperature parameter T and the humidity parameter RH are both less than or equal to the set value, that is, T≤Ts and RH≤RHs.

8. The control method of the refrigeration unit according to claim 7, characterized in that: The start and stop of the refrigeration unit and the determination and adjustment of the operation mode are realized through the dead zone control of the temperature T and relative humidity RH dual indicators; The startup operating condition is adjusted to any one of the temperature parameter T and the relative humidity parameter RH exceeding the upper limit of the dead zone, that is, T>Ts+Tx or RH>RHs+RHx, where Tx is the temperature deviation setting value and RHx is the relative humidity deviation setting value; The cooling mode operating condition is adjusted to the temperature parameter T exceeding the upper limit of the dead zone, that is, T>Ts+Tx; The operating conditions of the heating and dehumidification mode are adjusted to the relative humidity parameter RH exceeding the upper limit of the dead zone, that is, RH>RHs+RHx; The shutdown condition is adjusted to that the temperature parameter T and the humidity parameter RH are both less than or equal to the lower limit of the dead zone, that is, T≤Ts-Tx and RH≤RHs-RHx.

9. The control method of a refrigeration unit according to claim 5, characterized in that: The refrigeration unit enters the defrost mode at a fixed time; In defrost mode, when the defrost exit conditions are met, defrost ends; A defrost exit temperature probe is provided in the refrigeration coil (82), and the defrost exit condition is that the temperature Tcoil measured by the defrost exit temperature probe or the defrost exit time dt reaches a preset value, that is, Tcoil≥T0 or dt≥t0, wherein T0 is the preset value of the defrost exit temperature and t0 is the preset value of the defrost exit time.

10. The control method of the refrigeration unit according to claim 9, characterized in that: After defrosting is completed, the refrigeration unit performs the defrosting dripping procedure; During the defrosting and dripping procedure, the refrigeration solenoid valve (30), the dehumidification solenoid valve (40), the defrosting solenoid valve (50), and the liquid supply solenoid valve (100) are all closed, and the compressor (10) is stopped; After the defrost dripping program is completed, the standby program is executed.

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