Refrigeration system, defrosting control method and refrigeration equipment

Abstract

The present invention discloses a refrigeration system, a defrost control method and a refrigeration device. The refrigeration system includes: a compressor, a condenser and an evaporator group forming a refrigeration cycle loop, and the evaporator group is composed of at least two evaporators arranged in parallel. The refrigeration system also includes: a regenerator forming a heat recovery defrost loop with the compressor and the evaporator group, the first heat exchange pipeline of the regenerator is connected to the refrigeration cycle loop, and the refrigerant flowing out of the condenser can be sent to the evaporator through the first heat exchange pipeline of the regenerator; the second heat exchange pipeline of the regenerator is connected to the heat recovery defrost loop, and the refrigerant flowing out of the evaporator after defrosting can be sent back to the compressor through the second heat exchange pipeline of the regenerator; each evaporator can be independently switched to connect to the refrigeration cycle loop or the heat recovery defrost loop. The present invention ensures that defrosting is carried out normally while improving the supercooling degree of the refrigerant, avoiding the "liquid hammer" phenomenon and ensuring the normal flow and circulation of the refrigerant liquid after defrosting and condensation.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a refrigeration system, a defrosting control method and a refrigeration device. Background Art

[0002] Cold storage is a common refrigeration equipment. In the refrigeration system of large industrial cold storage, frosting is a very common phenomenon. It is generally believed that when air flows over the surface of the evaporator and the surface temperature of the evaporator is lower than 0℃, the evaporator will have surface frost. Since the thermal conductivity of the formed frost layer is low, the heat exchange performance of the evaporator is reduced, which not only increases energy consumption but also causes liquid inhalation to a certain extent.

[0003] Traditional technology usually uses hot fluorine defrosting to defrost the frosted evaporator of the low-temperature cold storage. Hot fluorine defrosting requires sufficient heat source - gaseous high-pressure and high-temperature refrigerant, which continuously enters the evaporator through the compressor exhaust pipe, thereby melting the frost layer. After the refrigerant defrost is completed, there are two ways to deal with it:

[0004] 1. After the refrigerant is defrosted and condensed into liquid, the refrigerant liquid is directly provided to other evaporators for evaporative cooling. The refrigerant liquid produced by the evaporator defrosting may cause the existence of gas-liquid mixture due to factors such as incomplete condensation, making the refrigerant flow unsmooth. After the defrosting is completed, the evaporator may have liquid. When the evaporator resumes cooling, it may cause "liquid hammer" to the compressor;

[0005] 2. After the refrigerant is defrosted and condensed into liquid, the liquid is not directly supplied to other evaporators, but directly enters the high-pressure liquid storage tank. Although this can avoid the adverse effects caused by the mixing of the defrosted liquid and the high-pressure direct liquid supply, the defrost pressure is usually lower than the normal refrigeration condensation pressure, resulting in the discharge liquid not being able to enter the high-pressure liquid storage tank normally.

[0006] Therefore, how to overcome the shortcomings of the existing hot fluorine defrosting method and achieve synchronous operation of refrigeration and defrosting is a technical problem that the industry urgently needs to solve. Summary of the invention

[0007] In order to solve the above-mentioned defects of the existing hot fluorine defrost technology, the present invention proposes a refrigeration system, a defrost control method and a refrigeration equipment. The refrigeration system introduces the refrigerant liquid that undergoes phase change after defrosting into a heat regenerator to exchange heat with the refrigerant under refrigeration conditions, thereby ensuring normal defrosting while increasing the refrigerant supercooling, avoiding the "liquid hammer" phenomenon and ensuring the normal flow and circulation of the refrigerant liquid after defrosting and condensation.

[0008] The technical solution adopted by the present invention is to design a refrigeration system, including: a compressor, a condenser and an evaporator group forming a refrigeration cycle loop, and the evaporator group is composed of at least two evaporators arranged in parallel.

[0009] The refrigeration system also includes: a regenerator that forms a heat recovery and defrost circuit with the compressor and the evaporator group, the first heat exchange pipeline of the regenerator is connected to the refrigeration cycle circuit, and the refrigerant flowing out of the condenser can be sent to the evaporator through the first heat exchange pipeline of the regenerator; the second heat exchange pipeline of the regenerator is connected to the heat recovery and defrost circuit, and the refrigerant flowing out of the evaporator after defrosting can be sent back to the compressor through the second heat exchange pipeline of the regenerator; each evaporator can be independently switched to connect to the refrigeration cycle circuit or the heat recovery and defrost circuit.

[0010] Furthermore, the first heat exchange pipeline of the regenerator is connected to the refrigeration inlet of the evaporator group through the liquid supply manifold, and the refrigeration outlet of the evaporator group is connected to the exhaust port of the compressor through the defrost manifold; the second heat exchange pipeline of the regenerator is connected to the refrigeration inlet of the evaporator group through the liquid return manifold, and the refrigeration outlet of the evaporator group is connected to the suction port of the compressor through the air return manifold. The liquid supply manifold, liquid return manifold, defrost manifold and air return manifold are all provided with liquid separation ports corresponding to each evaporator, and each liquid separation port is installed with an independently working valve.

[0011] Furthermore, the refrigeration inlet end of each evaporator is connected to the liquid supply manifold and the return liquid manifold through two parallel branches. One branch is equipped with a refrigeration throttling device and a switching valve, and the other branch is equipped with a one-way valve. The switching valve is opened when the evaporator is connected to the refrigeration cycle loop, and the one-way valve only allows the refrigerant to flow out of the refrigeration inlet end of the evaporator.

[0012] Furthermore, a heat recovery throttling device and a heat recovery control valve are installed at the inlet of the second heat exchange pipeline of the heat regenerator, and the heat recovery control valve remains closed when all evaporators are connected to the refrigeration cycle loop.

[0013] Furthermore, each evaporator is individually equipped with an electric heating device.

[0014] The present invention also proposes a defrost control method for the above refrigeration system, comprising:

[0015] Determine whether the refrigeration evaporator connected to the refrigeration cycle has reached the defrosting start condition;

[0016] If so, the refrigeration evaporator that meets the defrost start conditions will be used as the pending evaporator, and it will be determined whether the ratio of the sum of the cooling capacity of all the pending evaporators to the total cooling capacity of the refrigeration system exceeds the set value. If so, some of the pending evaporators will be selected according to the set logic to enter the heat recovery defrost mode. If not, all the pending evaporators will be turned on to enter the heat recovery defrost mode.

[0017] Further, selecting some pending evaporators to enter the reheating defrosting mode according to the set logic includes:

[0018] Sort the evaporators to be determined according to their cooling capacity;

[0019] The cooling capacities of the evaporators to be determined are superimposed in order from small to large to obtain the verification cooling capacity, and after each superposition, the verification ratio of the current verification cooling capacity to the total cooling capacity of the refrigeration system is calculated;

[0020] A calibration ratio value that is below the set value and closest to the set value is selected, and the corresponding pending evaporator is turned on according to the calibration refrigeration capacity of the calibration ratio to enter the heat recovery defrost mode.

[0021] Furthermore, the defrost control method further includes:

[0022] When the ratio of the sum of the cooling capacities of all pending evaporators to the total cooling capacity of the refrigeration system exceeds the set value, the minimum cooling capacity among all pending evaporators is first screened out;

[0023] Determine whether the ratio of the minimum cooling capacity to the total cooling capacity of the refrigeration system exceeds the set value;

[0024] If yes, all pending evaporators are turned on to enter the electric defrost mode, and the corresponding electric heating devices of the pending evaporators are turned on when entering the electric defrost mode;

[0025] If not, some of the pending evaporators are selected to enter the regenerative defrost mode according to the set logic, and the pending evaporators are connected to the regenerative defrost circuit when entering the regenerative defrost mode.

[0026] Furthermore, the defrost control method further includes:

[0027] After selecting some pending evaporators to enter the regenerative defrosting mode according to the set logic;

[0028] Determine whether any pending evaporator has reached the defrosting end condition;

[0029] If so, the pending evaporator is restored to the refrigeration evaporator and reconnected to the refrigeration cycle, and the process returns to determine whether the ratio of the sum of the refrigeration capacities of the remaining pending evaporators to the total refrigeration capacity of the refrigeration system exceeds the set value.

[0030] Furthermore, the defrost control method further includes: after all pending evaporators are turned on to enter a heat recovery defrost mode;

[0031] After the pending evaporator enters the reheating defrosting mode;

[0032] Determine whether any pending evaporator has reached the defrosting end condition;

[0033] If so, the pending evaporator is reconnected to the refrigeration cycle as a refrigeration evaporator to determine whether all the pending evaporators are connected to the refrigeration cycle. If so, return to determine whether the refrigeration evaporator connected to the refrigeration cycle meets the defrost start condition.

[0034] Furthermore, the cooling capacity of the pending evaporator is the product of the inlet and outlet enthalpy difference of the pending evaporator and the refrigerant mass flow rate, and the total cooling capacity of the refrigeration system is the product of the inlet and outlet enthalpy difference of the refrigeration system and the total refrigerant mass flow rate.

[0035] The present invention also proposes a refrigeration device, comprising: a refrigeration system and a controller for controlling the operating state of the refrigeration system, and the controller executes the above-mentioned defrost control method.

[0036] In one embodiment, the refrigeration equipment is a cold storage.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Design a regenerator in the refrigeration system to introduce the refrigerant liquid that has undergone phase change after defrosting into the regenerator for heat exchange with the refrigerant flowing out of the condenser, so as to achieve simultaneous defrosting and refrigeration, improve the refrigerant supercooling degree and ensure normal defrosting, avoid the "liquid hammer" phenomenon and ensure the normal flow and circulation of the refrigerant liquid after defrosting and condensation;

[0039] 2. Design the liquid supply header, defrost header, liquid return header and gas return header. Each header is equipped with the same number of liquid distribution ports as the evaporators to achieve independent control of each evaporator and ensure balanced distribution of refrigerant;

[0040] 3. According to the relationship between the cooling capacity of the evaporator to be determined and the total cooling capacity of the refrigeration system, different defrosting strategies are adjusted. The defrosting process is continuous and fast while ensuring the temperature of the cold storage is stable, thereby improving the use effect of the cold storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0042] Figure 1 It is a connection diagram of the refrigeration system in the present invention;

[0043] Figure 2 is a refrigerant flow diagram of the refrigeration cycle in the present invention;

[0044] Figure 3 It is a refrigerant flow diagram of the heat recovery defrosting circuit in the present invention;

[0045] Figure 4 It is a flow chart of the defrosting control method of the present invention. DETAILED DESCRIPTION

[0046] like Figure 1As shown, the refrigeration system proposed in the present invention is suitable for refrigeration equipment, especially cold storage, etc. The refrigeration system includes: a compressor 1, a condenser 3, a regenerator 4 and an evaporator group 5, etc. The evaporator group 5 is composed of at least two evaporators arranged in parallel, and the evaporators can be installed in different rooms. The compressor 1, the condenser 3 and the evaporator group 5 are connected to form a refrigeration cycle loop, the compressor 1, the evaporator group 5 and the regenerator 4 are connected to form a heat recovery defrosting loop, the exhaust port of the compressor 1 is connected to the oil separator 2, and the air intake port is connected to the gas-liquid separator 6. The refrigerant discharged from the exhaust port passes through the oil separator 2 and then enters the condenser 3 or the evaporator group 5, and the refrigerant entering the air intake port is separated by the gas-liquid separator 6.

[0047] The first heat exchange pipeline of the regenerator 4 is connected in the refrigeration cycle loop. The refrigerant flowing out of the condenser 3 can be sent to the evaporator through the first heat exchange pipeline of the regenerator 4. The second heat exchange pipeline of the regenerator 4 is connected in the heat recovery defrost loop. The refrigerant flowing out of the evaporator after defrosting can be sent back to the compressor 1 through the second heat exchange pipeline of the regenerator 4. Each evaporator can be independently switched to connect to the refrigeration cycle loop or the heat recovery defrost loop. The refrigerants in the refrigeration cycle loop and the heat recovery defrost loop are heat exchanged through the regenerator 4. The refrigerant in the second heat exchange pipeline absorbs the heat of the refrigerant in the first heat exchange pipeline, thereby increasing the supercooling of the refrigerant flowing out of the first heat exchange pipeline and ensuring normal defrosting.

[0048] The connection structure of the refrigeration system is described in detail below. The two ends of the evaporator group 5 are respectively a refrigeration inlet end and a refrigeration outlet end. Since the refrigerant flow direction of the evaporator in the heat recovery defrost circuit or the refrigeration cycle circuit is opposite, the refrigeration inlet end of the evaporator group 5 is actually a defrost outlet end, and the refrigeration outlet end is actually a defrost inlet end.

[0049] The first heat exchange pipeline of the regenerator 4 is connected to the refrigeration inlet end of the evaporator group 5 through the liquid supply manifold 7, the refrigeration outlet end of the evaporator group 5 is connected to the exhaust port of the compressor 1 through the defrost manifold 9, the second heat exchange pipeline of the regenerator 4 is connected to the refrigeration inlet end of the evaporator group 5 through the liquid return manifold 8, and the refrigeration outlet end of the evaporator group 5 is connected to the suction port of the compressor 1 through the return gas manifold 10. The end of each manifold connected to the evaporator group 5 is provided with a plurality of liquid separation ports which are the same as the number of evaporators, and the liquid separation ports are connected to each evaporator one by one, and each liquid separation port is installed with an independently working valve. Specifically, each liquid separation port of the liquid supply manifold 7 is installed with a liquid supply solenoid valve, each liquid separation port of the liquid return manifold 8 is installed with a liquid return solenoid valve, each liquid separation port of the defrost manifold 9 is installed with a defrost solenoid valve, and each liquid separation port of the return gas manifold 10 is installed with a return gas solenoid valve. The valves and liquid separation ports are used to realize the independent control of each evaporator, and ensure that the refrigerant can be evenly distributed.

[0050] The refrigeration inlet of each evaporator is connected to the liquid supply manifold 7 and the liquid return manifold 8 through two parallel branches. One branch is equipped with a refrigeration throttling device and a switching valve, and the other branch is equipped with a one-way valve. The switching valve is opened when the evaporator is connected to the refrigeration cycle, and the one-way valve only allows the refrigerant to flow out of the refrigeration inlet of the evaporator. The second heat exchange pipeline inlet of the regenerator 4 is equipped with a regenerative throttling device and a regenerative control valve 11. The regenerative control valve 11 remains closed when all evaporators are connected to the refrigeration cycle, and the regenerative control valve 11 is opened when an evaporator is connected to the regenerative defrosting circuit. The refrigerant liquid that undergoes phase change after defrosting is throttled and depressurized through the refrigeration throttling device, and is introduced into the regenerator 4 to exchange heat with the refrigerant flowing out of the condenser 3, so as to realize the simultaneous defrosting and refrigeration conditions, ensure the continuous and rapid defrosting process, and at the same time, the refrigeration of other evaporators is operating normally to avoid the "liquid hammer" phenomenon.

[0051] like Figure 1 As shown, taking the evaporator group consisting of four evaporators 5-1~5-4 as an example, the liquid supply solenoid valves of the four evaporators are 7-1~7-4 from left to right, the liquid return solenoid valves are 8-1~8-4 from left to right, the defrost solenoid valves are 9-1~9-4 from left to right, and the return air solenoid valves are 10-1~10-4 from right to left. The working process of the refrigeration system is as follows.

[0052] like Figure 2 As shown, all evaporators are in cooling mode, liquid supply solenoid valves 7-1~7-4 are open, liquid return solenoid valves 8-1~8-4 are closed, defrost solenoid valves 9-1~9-4 are closed, and air return solenoid valves 10-1~10-4 are open. The refrigerant flow direction is: high temperature and high pressure gaseous refrigerant → oil separator → condenser → regenerator → liquid supply header → liquid supply solenoid valve → refrigeration throttling device → evaporator → air return header → gas-liquid separator → compressor suction port.

[0053] like Figure 3 As shown, some evaporators enter the heat recovery defrosting mode and the other evaporators are in the refrigeration mode. Take the evaporator 5-1 defrosting and the evaporators 5-2, 5-3, and 5-4 refrigerating as an example: the defrost solenoid valve 9-1 is opened, and the defrost solenoid valves 9-2, 9-3, and 9-4 are closed; the liquid supply solenoid valve 7-1 is closed, and the liquid supply solenoid valves 7-2, 7-3, and 7-4 are opened; the return liquid solenoid valve 8-1 is opened, and the return liquid solenoid valves 8-2, 8-3, and 8-4 are closed. The refrigerant flow direction in the refrigeration mode is: high-temperature and high-pressure gaseous refrigerant → oil separator → condenser → regenerator → liquid supply header → liquid supply solenoid valve → refrigeration throttling device → evaporator → return air header → gas-liquid separator → compressor suction port; the refrigerant flow direction in the heat recovery defrost mode is: high-temperature and high-pressure gaseous refrigerant → oil separator → defrost header → defrost solenoid valve → evaporator → check valve → liquid return solenoid valve → heat recovery control valve → heat recovery throttling device → regenerator → gas-liquid separator → compressor suction port.

[0054] Furthermore, in order to speed up the defrosting efficiency of the evaporator, each evaporator is individually installed with an electric heating device. When the evaporator group is seriously frosted, the evaporator is heated and defrosted by the electric heating device. The evaporator can complete defrosting in a shorter time, ensuring that the refrigeration system can meet the defrosting requirements under any circumstances.

[0055] like Figure 3 As shown, the present invention also proposes a defrost control method for the above refrigeration system, comprising:

[0056] Determine whether the indoor temperature drops to the required temperature, close the liquid supply solenoid valve, return air solenoid valve, return liquid solenoid valve, and defrost solenoid valve on the corresponding branch of the evaporator in the room whose temperature drops to the required temperature, and open the liquid supply solenoid valve, return liquid solenoid valve, defrost solenoid valve, and return air solenoid valve on the corresponding branch of the evaporator in the room whose temperature is higher than the required temperature;

[0057] Determine whether the refrigeration evaporator connected to the refrigeration cycle has reached the defrosting start condition;

[0058] If so, the refrigeration evaporator that meets the defrost start condition is used as the pending evaporator, and it is determined whether the ratio of the sum of the cooling capacity of all the pending evaporators to the total cooling capacity of the refrigeration system exceeds the set value. If so, some of the pending evaporators are selected according to the set logic to enter the regenerative defrost mode. If not, all the pending evaporators are turned on to enter the regenerative defrost mode.

[0059] If not, the process returns to determine whether the refrigeration evaporator meets the defrost start condition.

[0060] The defrost control method adjusts different defrost strategies according to the relationship between the refrigeration capacity of the pending evaporator that meets the defrost start condition and the total refrigeration capacity of the refrigeration system. The defrost process is continuous and fast while ensuring the temperature of the cold storage is stable, thereby improving the use effect of the cold storage.

[0061] It should be pointed out that the refrigeration capacity of the evaporator to be determined is the product of the inlet and outlet enthalpy difference of the evaporator to be determined and the mass flow rate of the refrigerant, and the total refrigeration capacity of the refrigeration system is the product of the inlet and outlet enthalpy difference of the refrigeration system and the total mass flow rate of the refrigerant. In actual application, a flow detection device is installed at the inlet or outlet of each evaporator, and the refrigerant mass flow of the evaporator is detected by the flow detection device. A temperature sensor and a pressure sensor are installed at the inlet and outlet of each evaporator, and the inlet and outlet enthalpy difference of the evaporator is obtained by the detection data of the temperature sensor and the pressure sensor. A flow detection device is installed at the exhaust port or the air intake port of the compressor, and the total refrigerant mass flow of the refrigeration system is detected by the flow detection device. A temperature sensor and a pressure sensor are installed at the exhaust port and the air intake port of the compressor, and the inlet and outlet enthalpy difference of the refrigeration system is obtained by the detection data of the temperature sensor and the pressure sensor. Of course, the installation method of the flow detection device can be designed according to the specific situation, and the refrigeration capacity can also be reflected by other parameters or detected by other equipment, and the present invention is not limited to this.

[0062] In some embodiments, the implementation process of selecting some pending evaporators to enter the regenerative defrosting mode according to the set logic is as follows:

[0063] Sort the evaporators to be determined according to their cooling capacity;

[0064] The cooling capacities of the evaporators to be determined are superimposed in order from small to large to obtain the verification cooling capacity, and after each superposition, the verification ratio of the current verification cooling capacity to the total cooling capacity of the refrigeration system is calculated;

[0065] A calibration ratio value that is below the set value and closest to the set value is selected, and the corresponding pending evaporator is turned on according to the calibration refrigeration capacity of the calibration ratio to enter the heat recovery defrost mode.

[0066] The set value can be designed according to the actual situation of the refrigeration system. Generally speaking, the set value is between 0 and 30%. It is best when the set value is one-fourth. At this ratio, the evaporator to be determined is selected to enter the heat recovery defrost mode, which can maximize the defrost speed and keep the temperature of the cold storage stable.

[0067] After the defrost strategy is made in the above defrost control method, different defrost strategies have corresponding defrost exit execution processes.

[0068] The first is to select some pending evaporators to enter the defrost exit execution process of the regenerative defrost mode according to the set logic:

[0069] After the pending evaporator enters the regenerative defrosting mode, the defrost solenoid valve of the pending evaporator is opened, the liquid supply solenoid valve is closed, the air return solenoid valve is closed, the liquid return solenoid valve is opened, and the regenerative solenoid valve of the regenerator is opened;

[0070] Determine whether any pending evaporator has reached the defrosting end condition;

[0071] If so, the pending evaporator is restored to the refrigeration evaporator and reconnected to the refrigeration cycle circuit. The defrost solenoid valve of the refrigeration evaporator is closed, the liquid supply solenoid valve is opened, the return air solenoid valve is opened, and the return liquid solenoid valve is closed. The system returns to determine whether the ratio of the sum of the cooling capacities of the remaining pending evaporators to the total cooling capacity of the refrigeration system exceeds the set value.

[0072] The second is to start all pending evaporators and enter the defrost exit execution process of the heat recovery defrost mode:

[0073] After the pending evaporator enters the reheating defrosting mode;

[0074] Determine whether any pending evaporator has reached the defrosting end condition;

[0075] If so, the pending evaporator is reconnected to the refrigeration cycle as a refrigeration evaporator to determine whether all pending evaporators are connected to the refrigeration cycle. If so, return to determine whether the refrigeration evaporator meets the defrost start condition.

[0076] It should be understood that in the defrost control method, as the pending evaporators gradually complete defrosting, the number of remaining pending evaporators becomes smaller and smaller, and the ratio of the sum of the cooling capacity of all the remaining pending evaporators to the total cooling capacity of the refrigeration system will inevitably be less than or equal to the set value. At this time, all the remaining pending evaporators are turned on to enter the heat recovery defrost mode, and the above-mentioned second defrost exit execution process is executed.

[0077] In some embodiments, the defrost control method further includes:

[0078] When the ratio of the sum of the cooling capacities of all pending evaporators to the total cooling capacity of the refrigeration system exceeds the set value, the minimum cooling capacity among all pending evaporators is first screened out;

[0079] Determine whether the ratio of the minimum cooling capacity to the total cooling capacity of the refrigeration system exceeds the set value;

[0080] If yes, it means that the frost condition of the evaporator group is serious. All pending evaporators are turned on to enter the electric defrost mode. When the pending evaporators enter the electric defrost mode, the corresponding electric heating devices are turned on. The electric heating devices heat the evaporators to defrost quickly, shortening the defrost time and meeting the defrost requirements in any situation.

[0081] If not, it means that the frosting condition of the evaporator group is normal. According to the set logic, some of the pending evaporators are selected to enter the reheating defrost mode. When entering the reheating defrost mode, the pending evaporators are connected to the reheating defrost circuit, and the evaporators are defrosted by the high-temperature refrigerant of the refrigeration system itself, thereby reducing the power consumption caused by defrosting, saving energy and protecting the environment while ensuring the normal cooling of the refrigeration system.

[0082] It should be pointed out that the defrost start conditions and defrost end conditions mentioned above can adopt existing judgment conditions, such as the duration of the evaporator refrigeration operation as the defrost start condition, and the duration of the heat recovery defrost operation as the defrost exit condition. It is also possible to detect whether parameters such as the evaporator tube temperature reach the corresponding target temperature as a judgment condition. The present invention is not limited to this.

[0083] The present invention also provides a refrigeration device, comprising: a refrigeration system and a controller for controlling the operating state of the refrigeration system, and the controller executes the above-mentioned defrost control method.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A defrost control method for a refrigeration system, the refrigeration system comprising: A compressor, a condenser and an evaporator group forming a refrigeration cycle loop, wherein the evaporator group is composed of at least two evaporators arranged in parallel, and the refrigeration system further comprises: a regenerator forming a heat recovery and defrosting loop with the compressor and the evaporator group, wherein a first heat exchange pipeline of the regenerator is connected to the refrigeration cycle loop, and the refrigerant flowing out of the condenser can be sent to the evaporator through the first heat exchange pipeline of the regenerator, and the second heat exchange pipeline of the regenerator is connected to the heat recovery and defrosting loop, and the refrigerant flowing out of the evaporator after defrosting can be sent back to the compressor through the second heat exchange pipeline of the regenerator, and each of the evaporators can be independently switched to be connected to the refrigeration cycle loop or the heat recovery and defrosting loop; Characterized in that, the defrost control method comprises: Determining whether the refrigeration evaporator connected to the refrigeration cycle has reached the defrosting start condition; If so, the refrigeration evaporator that meets the defrost start-up conditions will be used as the standby evaporator, and it will be determined whether the ratio of the sum of the refrigeration capacity of all the standby evaporators to the total refrigeration capacity of the refrigeration system exceeds the set value. If so, some of the standby evaporators will be selected according to the set logic to enter the heat recovery defrost mode. If not, all the standby evaporators will be turned on to enter the heat recovery defrost mode.

2. The defrost control method according to claim 1, characterized in that: The first heat exchange pipeline of the regenerator is connected to the refrigeration inlet end of the evaporator group through the liquid supply header, and the refrigeration outlet end of the evaporator group is connected to the exhaust port of the compressor through the defrost header; the second heat exchange pipeline of the regenerator is connected to the refrigeration inlet end of the evaporator group through the liquid return header, and the refrigeration outlet end of the evaporator group is connected to the suction port of the compressor through the air return header; The liquid supply manifold, liquid return manifold, defrost manifold and gas return manifold are all provided with liquid separation ports connected to the respective evaporators in a one-to-one correspondence, and each liquid separation port is installed with an independently working valve.

3. The defrost control method according to claim 2, characterized in that: The refrigeration inlet end of each evaporator is connected to the liquid supply manifold and the liquid return manifold through two parallel branches. One branch is equipped with a refrigeration throttling device and a switching valve, and the other branch is equipped with a one-way valve. The switching valve is opened when the evaporator is connected to the refrigeration cycle circuit, and the one-way valve only allows the refrigerant to flow out of the refrigeration inlet end of the evaporator.

4. The defrost control method according to claim 1, characterized in that: A heat recovery throttling device and a heat recovery control valve are installed at the inlet of the second heat exchange pipeline of the heat regenerator, and the heat recovery control valve remains closed when all the evaporators are connected to the refrigeration cycle loop.

5. The defrost control method according to claim 1, characterized in that: Each of the evaporators is individually equipped with an electric heating device.

6. The defrost control method according to any one of claims 1 to 5, characterized in that: According to the setting logic selection part, the pending evaporator enters the regenerative defrost mode including: Sorting the pending evaporators according to the refrigeration capacity; The refrigeration capacities of the evaporators to be determined are sequentially superimposed from small to large to obtain the verification refrigeration capacity, and after each superposition, a verification ratio of the current verification refrigeration capacity to the total refrigeration capacity of the refrigeration system is calculated; A calibration ratio value that is below the set value and closest to the set value is selected, and a corresponding pending evaporator is turned on according to the calibration refrigeration capacity of the calibration ratio to enter a heat recovery defrosting mode.

7. The defrost control method according to any one of claims 1 to 5, characterized in that: Also includes: When the ratio of the sum of the refrigeration capacity of all the pending evaporators to the total refrigeration capacity of the refrigeration system exceeds a set value, firstly screening out the minimum refrigeration capacity among all the pending evaporators; Determining whether a ratio of the minimum cooling capacity to the total cooling capacity of the refrigeration system exceeds a set value; If yes, all the pending evaporators are turned on to enter the electric defrosting mode; If not, the pending evaporator enters the reheating defrost mode according to the setting logic selection part.

8. The defrost control method according to any one of claims 1 to 5, characterized in that: Also includes: After the pending evaporator enters the regenerative defrost mode as described in the setting logic selection part; Determine whether any of the pending evaporators has reached the defrosting end condition; If so, the pending evaporator is restored to a refrigeration evaporator and reconnected to the refrigeration cycle, and the process returns to determine whether the ratio of the sum of the refrigeration capacities of the remaining pending evaporators to the total refrigeration capacity of the refrigeration system exceeds a set value.

9. The defrost control method according to any one of claims 1 to 5, characterized in that: Also includes: After all the pending evaporators are turned on to enter the heat recovery defrosting mode; After the pending evaporator enters the heat recovery defrosting mode; Determine whether any of the pending evaporators has reached the defrosting end condition; If so, the pending evaporator is reconnected to the refrigeration cycle as a refrigeration evaporator to determine whether all the pending evaporators are connected to the refrigeration cycle. If so, return to determine whether the refrigeration evaporator connected to the refrigeration cycle meets the defrost start condition.

10. The defrost control method according to any one of claims 1 to 5, characterized in that: The pending evaporator is connected to the regenerative defrost circuit when entering the regenerative defrost mode, and the corresponding electric heating device of the pending evaporator is turned on when entering the electric defrost mode.

11. The defrost control method according to any one of claims 1 to 5, characterized in that: The cooling capacity of the evaporator to be determined is the product of the inlet and outlet enthalpy difference of the evaporator to be determined and the refrigerant mass flow rate, and the total cooling capacity of the refrigeration system is the product of the inlet and outlet enthalpy difference of the refrigeration system and the total refrigerant mass flow rate.

12. Refrigeration equipment, including: A refrigeration system and a controller for controlling the operating state of the refrigeration system, characterized in that the controller executes the defrost control method according to any one of claims 1 to 11.

13. The refrigeration device according to claim 12, characterized in that: The refrigeration equipment is a cold storage.

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