A wide-temperature-range refrigeration system with a double evaporator and a double condenser

Abstract

The present invention discloses a wide-temperature-range refrigeration system with double evaporators and double condensers, which includes a compressor, evaporators A and B, condensers A and B, throttling elements A, B, and C. There are two paths at the outlet of the compressor. One path is connected to the first solenoid valve and condenser A, and the other path is connected to the second solenoid valve and condenser B. After condensers A and B converge, they are connected to a liquid receiver, a dryer filter, and a sight glass, and then divided into three paths. The three paths are respectively connected to the inlets of throttling elements A, B, and C. The outlet of throttling element C is connected in parallel to the inlets of the third, fourth, and fifth solenoid valves. The outlet of the third solenoid valve converges with the outlet of throttling element A and then accesses the inlet of evaporator A. The outlet of the fourth solenoid valve converges with the outlet of throttling element B and then accesses the inlet of evaporator B. The outlet of the fifth solenoid valve converges with the outlets of evaporators A and B and then accesses the inlet of the gas-liquid separator. The outlet of the gas-liquid separator is connected to the compressor. The present invention can achieve energy-saving operation of the product through a small pressure ratio working mode.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration systems, and particularly to a wide-temperature-range refrigeration system with a double evaporator and a double condenser. Background Art

[0002] With the rapid development of electronic devices and equipment, people's requirements for traditional compression refrigeration are getting higher and higher, such as adapting to a wider ambient temperature, a safer, more reliable and power-saving operation mode to meet the iterative development of air conditioners and cold liquid equipment. Currently, single-loop vapor compression refrigeration systems are very common. Coupled with stepless speed regulation fans, DC variable frequency or multi-stage high-efficiency compressors, the rapid response, control and energy-saving operation of the refrigeration system have reached a certain level. However, at low compressor speeds (low displacement), the oil return inside the system becomes an inevitable technical problem. For example, when the gaseous flow rate of the refrigerant in the pipe is relatively low (<5 m / s), the compressor oil usually separates and cannot return to the compressor, resulting in an oil shortage failure. Therefore, people have thought of many methods, such as adding oil return bends (or oil pressure locks), double return air pipes and other measures. As the refrigeration capacity of the product increases, such as from dozens of kilowatts to several megawatts, when the supply air temperature or the supply liquid temperature approaches the set temperature, or when the load becomes smaller, the compressor will naturally switch to low frequency or low gear (such as the displacement drops to 25% - 50% of the rated displacement) operation. For relatively large condensers and evaporators, if overall heat exchange is still used at this time, problems such as oil shortage or oil return foaming will increase significantly. Therefore, in the industry, there are also methods to make the compressor have a working mode of accelerating oil return or simply avoiding the low-speed area through software control, but this brings relatively large temperature fluctuations.

[0003] Ordinary air conditioners generally have a compression ratio between 3 and 8. However, under low ambient temperature conditions, a small compression ratio (such as compression ratio ≤ 1.3) technology is applied to replace the heat pipe cycle or air-air heat exchange, that is, the original refrigeration system is used, and the compressor is switched to a small compression ratio working mode. At this time, the compressor only provides the power required for the refrigerant gas to flow, and makes full use of the outdoor natural cold source to achieve energy-saving operation, and its energy efficiency ratio is as high as 7.0 - 20. As we know, the lower the ambient temperature, the more excessive the heat exchange area of the original condenser will be, and the compressor will also have speed regulation or gear shifting, and will also face the problem of oil return. In addition, providing a small compression ratio means that the throttling element needs to provide more flow under a small pressure difference, and the original throttling element usually cannot meet the flow requirements.

[0004] How to more effectively correspond the refrigeration cycle to external environmental changes and load changes, combined with the modular development direction, group-control the condenser and the evaporator, and through adding some control valves, to achieve the reliable operation of the refrigeration system in a truly wide temperature range is worthy of exploration. Summary of the Invention

[0005] The present invention provides a wide-temperature-range refrigeration system with a double evaporator and a double condenser to solve the problem in the prior art that it is difficult to achieve reliable operation in a wide temperature range under a small pressure ratio.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A wide-temperature-range refrigeration system with a double evaporator and a double condenser, comprising a compressor, an evaporator A, an evaporator B, a condenser A, a condenser B, a throttling element A, a throttling element B, a throttling element C, a liquid receiver, a drying filter, a sight glass, and a gas-liquid separator, wherein:

[0008] The condenser A and the condenser B are independent of each other. The condenser A is equipped with a condensing fan A, and the condenser B is equipped with a condensing fan B;

[0009] The evaporator A and the evaporator B are two different heat exchange channels in the same double-loop heat exchanger for supplying cold liquid to cold liquid equipment; or the evaporator A and the evaporator B are independent of each other and share an evaporation fan and an air duct for supplying cold air for air conditioning;

[0010] Two pipelines are connected in parallel to the outlet of the compressor. The first pipeline at the outlet of the compressor is connected to the inlet of the condenser A through a first solenoid valve, and the second pipeline at the outlet of the compressor is connected to the inlet of the condenser B through a second solenoid valve. The outlets of the condenser A and the condenser B are merged and then sequentially connected to the inlet of the sight glass through the liquid receiver and the drying filter; three pipelines are connected in parallel to the outlet of the sight glass. The first pipeline at the outlet of the sight glass is connected to the inlet of the throttling element A, the second pipeline at the outlet of the sight glass is connected to the inlet of the throttling element B, and the third pipeline at the outlet of the sight glass is connected to the inlet of the throttling element C. The outlet of the throttling element C is connected to the inlets of a third solenoid valve, a fourth solenoid valve, and a fifth solenoid valve in parallel. Among them, the outlet of the third solenoid valve converges with the outlet of the throttling element A and then is connected to the inlet of the evaporator A, the outlet of the fourth solenoid valve converges with the outlet of the throttling element B and then is connected to the inlet of the evaporator B, and the outlet of the fifth solenoid valve converges with the outlets of the evaporator A and the evaporator B and then is connected to the inlet of the gas-liquid separator. The outlet of the gas-liquid separator is connected to the inlet of the compressor.

[0011] Further, the heat exchange area ratio of the evaporator A to the evaporator B is between 2.5:7.5 and 1:1; the heat exchange area ratio of the condenser A to the condenser B is between 2.5:7.5 and 1:1.

[0012] Further, when used for air conditioning air supply, the evaporator A, the evaporator B, the condenser A, and the condenser B are all copper tube fin heat exchangers or microchannel heat exchangers.

[0013] Further, the throttling element A, the throttling element B, and the throttling element C are all electronic expansion valves, or electronic control valves, or solenoid valves, or thermostatic expansion valves.

[0014] Further, the compressor is a variable displacement compressor.

[0015] Further, the condenser A and condenser B are subdivided into several modules, and each module is equipped with a condensing fan when divided into several modules.

[0016] Further, auxiliary electric heating is provided in the accumulator and the gas-liquid separator respectively.

[0017] Further, the gas-liquid separator adopts a double return gas structure.

[0018] Further, the first solenoid valve and the second solenoid valve are normally open, and the third solenoid valve, the fourth solenoid valve and the fifth solenoid valve are normally closed.

[0019] The present invention can select a suitable working mode according to different working conditions of normal temperature, high temperature and low temperature, including:

[0020] Under normal temperature working conditions, when the load is large, 2 groups of evaporators and 2 groups of condensers work together, and when the load is small, 1 group of evaporators and 1 group of condensers work;

[0021] Under high temperature working conditions, 1 group of evaporators and 2 groups of condensers are used as the high temperature start-up mode. After start-up, when the load is large, 2 groups of evaporators and 2 groups of condensers work together, and when the load is small, 1 group of evaporators and 1 group of condensers work. When the compressor is overheated and overloaded, the throttling element C and the fifth solenoid valve are opened for liquid injection cooling;

[0022] Under low temperature working conditions, when the load is large, 2 groups of evaporators and 2 groups of condensers work together, and when the load is small, 1 group of evaporators and 1 group of condensers work. At the same time, the throttling element C and the corresponding third solenoid valve and (or) fourth solenoid valve are opened to enter the small pressure ratio working mode.

[0023] In the present invention, when the throttling element C and the third solenoid valve are opened, they can work in parallel or independently with the throttling element A to provide a small pressure ratio mode for the evaporator A; when the throttling element C and the fourth solenoid valve are opened, they can work in parallel or independently with the throttling element B to provide a small pressure ratio mode for the evaporator B; the system compression ratio is the ratio of the condensing side P1 to the evaporating side P2, and the small pressure ratio is generally 1.05 - 1.8.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] 1. The present invention uses 2 groups of evaporators, 2 groups of condensers, 3 groups of throttling elements and 5 groups of solenoid valves to realize different refrigeration operation modes under normal temperature, high temperature and low temperature working conditions and different loads, making the evaporators, condensers and compressors more matched and the system performance better.

[0026] 2. Under low temperature working conditions, the present invention realizes energy-saving operation through the small pressure ratio working mode.

[0027] 3. By adding throttle element C, the present invention can achieve high-temperature liquid injection cooling, provide a larger flow rate at low temperature, and at the same time, it can be used as a backup at any time when the other throttle element fails.

[0028] 4. Based on the modular design concept, the principle of the present invention is simple, which is convenient for expansion and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the schematic structural diagram of the present invention when used in a cold liquid device in an embodiment.

[0030] Figure 2 It is the schematic structural diagram of the present invention when used in an air conditioner in an embodiment.

[0031] Figure 3 It is the schematic structural diagram of the condensation part evolution of the present invention in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described below with reference to the drawings and embodiments.

[0033] This embodiment discloses a wide-temperature refrigeration system with a double evaporator and a double condenser, as Figure 1 、 Figure 2 shown. In the figure, represents the air flow direction, represents the refrigerant flow direction under normal temperature conditions, represents the flow direction of the increased flow branch under low temperature conditions, represents the flow direction of the superheat control branch under high temperature conditions.

[0034] This embodiment includes a compressor 1, an evaporator A 10.1, an evaporator B 10.2, a condenser A 3.1, a condenser B 3.2, a throttle element A 8.1, a throttle element B 8.2, a throttle element C 8.3 and five groups of solenoid valves, as well as a liquid receiver 5.1, a dryer filter 6, a sight glass 7, and a gas-liquid separator 11.1.

[0035] In this embodiment, the condenser A 3.1 and the condenser B 3.2 are independent units. The condenser A 3.1 is equipped with a condenser fan A 4.1, and the condenser B 3.2 is equipped with a condenser fan B 4.2.

[0036] As Figure 1As shown in the figure, when this embodiment is used to supply cold liquid to a cold liquid device, a double-circuit heat exchanger 10 is used as evaporators A10.1 and B10.2. The double-circuit heat exchanger 10 includes three heat exchange channels. The middle heat exchange channel serves as the coolant channel for flowing through the circulating coolant, and the two side heat exchange channels serve as evaporators A10.1 and B10.2 respectively for flowing through the refrigerant of evaporators A10.1 and B10.2. In addition, when used to supply liquid to the cold liquid device, two heat exchangers can also be integrated and combined to serve as evaporators A10.1 and B10.2 respectively.

[0037] As Figure 2 shown in the figure, when this embodiment is used to supply cold air by an air conditioner, evaporators A10.1 and B10.2 are independent of each other, and evaporators A10.1 and B10.2 share an evaporation fan 12 and an air duct.

[0038] Two pipelines are connected in parallel at the outlet of the compressor 1. The first pipeline is connected to the inlet of condenser A3.1 through the first solenoid valve 2.1, and the second pipeline is connected to the inlet of condenser B3.2 through the second solenoid valve 2.2. The outlets of condenser A3.1 and condenser B3.2 are merged and then connected to the inlet of the liquid receiver 5.1, the dryer filter 6 in sequence, and then connected to the inlet of the sight glass 7.

[0039] Three pipelines are connected in parallel at the outlet of the sight glass 7. The first pipeline is connected to the inlet of throttle element A8.1, the second pipeline is connected to the inlet of throttle element B8.2, and the third pipeline is connected to the inlet of throttle element C8.3. The outlet of throttle element C8.3 is connected in parallel to the inlets of the third solenoid valve 9.1, the fourth solenoid valve 9.2, and the fifth solenoid valve 9.3. Among them, the outlet of the third solenoid valve 9.1 is merged with the outlet of throttle element A8.1 and then connected to the inlet of evaporator A10.1. The outlet of the fourth solenoid valve 9.2 is merged with the outlet of throttle element B8.2 and then connected to the inlet of evaporator B10.2. The outlet of the fifth solenoid valve 9.3 is merged with the outlets of evaporator A10.1 and evaporator B10.2 and then connected to the inlet of the gas-liquid separator 11.1. The outlet of the gas-liquid separator 11.1 is connected to the inlet of the compressor 1, thus forming a refrigeration cycle system.

[0040] This embodiment can select a suitable working mode according to normal temperature, high temperature and low temperature working conditions, including:

[0041] Under normal temperature working conditions, when the load is large, two groups of evaporators and two groups of condensers work together, and when the load is small, one group of evaporators and one group of condensers work.

[0042] Under high-temperature working conditions, one set of evaporators and two sets of condensers are used as the high-temperature startup mode. After startup, when the load is large, two sets of evaporators and two sets of condensers work together. When the load is small, one set of evaporators and one set of condensers work. And when the compressor is overheated and overloaded, the throttling element C8.3 and the fifth solenoid valve 9.3 are opened for liquid injection cooling.

[0043] Under low-temperature working conditions, when the load is large, two sets of evaporators and two sets of condensers work together. When the load is small, one set of evaporators and one set of condensers work. At the same time, the throttling element C8.3 and the corresponding third solenoid valve 9.1 and / or the fourth solenoid valve 9.2 are opened to enter the small pressure ratio working mode.

[0044] In this embodiment, the heat transfer area ratio of evaporator A10.1 and evaporator B10.2 is between 2.5:7.5 and 1:1. Similarly, the heat transfer area ratio of condenser A3.1 and condenser B3.2 is between 2.5:7.5 and 1:1. When used for air conditioners, both two sets of evaporators and two sets of condensers are copper tube fin heat exchangers or microchannel heat exchangers. When used for cold liquid equipment, evaporator A10.1 and evaporator B10.2 are double-circuit heat exchangers 10.

[0045] In this embodiment, the throttling element A8.1, the throttling element B8.2 and the throttling element C8.3 are closed when not working. Specifically, electronic expansion valves or electronic control valves are used. In the case of similar principles, a combination of solenoid valves and thermal expansion valves can also be used for substitution.

[0046] When the throttling element C8.3 and the third solenoid valve 9.1 are opened, they can work in parallel or independently with the throttling element A8.1 to provide a small pressure ratio mode for evaporator A10.1. When the throttling element C8.3 and the fourth solenoid valve 9.2 are opened, they can work in parallel or independently with the throttling element B8.2 to provide a small pressure ratio mode for evaporator B10.2. The system compression ratio is the ratio of the condensation side P1 to the evaporation side P2. The small pressure ratio is generally 1.05 - 1.8.

[0047] In this embodiment, the compressor is a variable displacement compressor, and a stepped unloading compressor, a variable frequency compressor, etc. can be used.

[0048] In this embodiment, the condensation fan A4.1 and the condensation fan B4.2 are adjustable speed fans, and their quantity and air volume are determined according to the condensation heat dissipation capacity of each.

[0049] In this embodiment, the liquid receiver 5.1 and the gas-liquid separator 11.1 are respectively provided with auxiliary electric heaters 5.2 and 11.2 for low-temperature working conditions.

[0050] In this embodiment, the gas-liquid separator 11.1 should meet the normal oil return under small displacement, and a double return air structure can be specifically adopted.

[0051] In this embodiment, the first solenoid valve 2.1 and the second solenoid valve 2.2 are normally open, and the third solenoid valve 9.1, the fourth solenoid valve 9.2 and the fifth solenoid valve 9.2 are normally closed.

[0052] This embodiment is further described as follows:

[0053] For example, for an air conditioner with a cooling capacity of 25 kW, refrigerant R134a, the indoor fan air volume Q 内风 = 4400 m 3 / h, the air pressure P 内风 = 300 Pa, the outdoor fan air volume Q 外风 = 2´7500 m 3 / h, the air pressure P 外风 = 80 Pa, and 2 groups of evaporators and 2 groups of condensers are designed with a heat transfer area ratio of 1:1, that is, the same heat transfer design.

[0054] Under normal temperature conditions, taking the evaporation temperature as 7 °C, the superheat as 5 °C, the condensation temperature as 54 °C, and the subcooling as 3 °C, the corresponding thermodynamic cycle diagram is obtained through the refrigerant pressure-enthalpy diagram, and the enthalpy values of the refrigerant entering the evaporator, entering the compressor and leaving the compressor are found to be 273.0 kJ / kg, 406.3 kJ / kg and 434.3 kJ / kg respectively. The specific volume of the refrigerant entering the compressor is V = 0.0561 m 3 / kg, taking the compressor volumetric efficiency l = 0.85 and the efficiency h = 0.68, then:

[0055] The unit refrigerating capacity q = 406.3−273.0 = 133.3 kJ / kg

[0056] The unit theoretical compression work AL = 434.3−406.3 = 28 kJ / kg

[0057] The refrigerant circulation rate G = Q / q = 25´3600 / 133.3≈675 kg / h

[0058] The theoretical displacement of the compressor V = G×V / l = 675´0.0561 / 0.85≈44.55 m 3 / h

[0059] The compressor power N = G∙AL / h = 675´28 / 0.68 = 27794 kJ / h≈7721W

[0060] If the evaporator uses a copper tube of F9.52´0.35mm, with an aluminum sheet of df = 0.15mm thickness on the outside, the fin pitch is 2.0mm, the fin shape is corrugated, the tube pitch is 25.4mm, and the row pitch is 22mm, then the total length of the evaporator tubes is about 180m, the number of circuits n = 20, each circuit is 9m, according to the theoretical displacement of the compressor 44.55 m 3Calculated at / h, when the displacement is 100%, the flow velocity in the pipe is:

[0061] V = 100%V / (π∙r 2 ) / n = 44.55 / 3600 / (3.14 × 0.004412) / 20 ≈ 10 m / s

[0062] When the displacement is 25%, the flow velocity in the pipe is:

[0063] V = 25%V / (π∙r 2 ) / n = 0.25 × 44.55 / 3600 / (3.14 × 0.004412) / 20 ≈ 2.5 m / s

[0064] This means that when the compressor has a low displacement, the refrigerant flow velocity is correspondingly very low, which is likely to cause problems such as oil return.

[0065] Under low-temperature conditions, taking the evaporation temperature as 7°C, the superheat as 5°C, the condensation temperature as 12°C, and the subcooling as 3°C, the corresponding thermodynamic cycle diagram is obtained through the refrigerant pressure-enthalpy diagram, and the enthalpy values entering the evaporator, entering the compressor, and leaving the compressor are found to be 211.8 kJ / kg, 406.3 kJ / kg, and 409.7 kJ / kg respectively. The specific volume entering the compressor is V = 0.0561 m 3 / kg. Taking the compressor volumetric efficiency l = 0.85 and the efficiency h = 0.68, then:

[0066] The refrigerating capacity per unit q = 406.3 - 211.8 = 194.5 kJ / kg

[0067] The unit theoretical compression work AL = 409.7 - 406.3 = 3.4 kJ / kg

[0068] The refrigerant circulation rate G = Q / q = 25 × 3600 / 194.5 ≈ 463 kg / h

[0069] The theoretical displacement of the compressor V = G × V / l = 463 × 0.0561 / 0.85 ≈ 30.56 m 3 / h

[0070] The compressor power N = G ∙ AL / h = 463 × 3.4 / 0.68 = 2315 kJ / h ≈ 643 W

[0071] Calculated based on the theoretical displacement of the compressor of 30.56 m 3 / h, the flow velocity in the pipe is:

[0072] V = 100%V / (π∙r 2 ) / n = 30.56 / 3600 / (3.14 × 0.004412) / 20 ≈ 7 m / s

[0073] Under low-temperature conditions, the compressor displacement is approximately 30.56 / 44.55≈69% of the rated displacement at normal temperature. At this time, both groups of evaporators are fully operational, and the gaseous refrigerant velocity is 7 m / s, without problems such as difficult oil return. When the load is small, when the compressor displacement is as low as 25% of the rated displacement at normal temperature, one group of evaporators is utilized, and the gaseous refrigerant velocity inside the pipe can still be maintained at 5.1 m / s, avoiding problems such as difficult oil return.

[0074] The power consumption of this embodiment is further described as follows:

[0075] To illustrate the energy-saving operation of the small pressure ratio mode under low-temperature conditions, through simplified theoretical calculations, the product power consumption includes four parts: the compressor, condenser fan A, condenser fan B, and evaporation fan. Among them, the fan power is calculated using the formula N 风 =k∙Q 风 ∙P 风 / h. In the formula, h is the product of the internal efficiency and mechanical efficiency of the fan, uniformly taken as 0.75, and the safety factor k is uniformly taken as 1.2. Then the indoor-side fan power:

[0076] N 内风 =k∙(Q 内风 / 3600)∙P 内风 / h = 1.2´(4400 / 3600)´300 / 0.75≈587 W

[0077] The power of a single outdoor-side fan:

[0078] N 外风 =k∙(Q 内风 / 3600)∙P 内风 / h = 1.2´(7500 / 3600)´80 / 0.75≈267 W

[0079] The theoretical power consumption at normal temperature is approximately: 7721 + 587 + 2´267 = 8842 W, and the energy efficiency ratio EER = 25000 / 8842≈2.83.

[0080] The theoretical power consumption at low temperature is approximately: 643 + 587 + 267 = 1497 W, and the energy efficiency ratio EER = 25000 / 1497≈16.70.

[0081] As can be seen above, by adopting the small pressure ratio mode at low temperature and making full use of natural cold sources, energy-saving operation can be achieved, and the EER efficiency is increased from 2.83 at normal temperature to 16.70 at low temperature. Especially when the outdoor ambient temperature is more than 20°C lower than the indoor temperature, the larger the temperature difference, the more obvious the effect, and the energy efficiency ratio even exceeds 20.0.

[0082] Regarding the system pressure ratio, assuming the evaporation temperature remains unchanged, taking the saturation evaporation pressure (absolute pressure) corresponding to 7°C as 3.75 bar, then

[0083] Under high-temperature conditions, the saturated evaporation pressure (absolute pressure) corresponding to a condensation temperature of 70°C is 21.17 bar, so the system pressure ratio = 21.17 / 3.75 = 5.65;

[0084] Under normal-temperature conditions, the saturated evaporation pressure (absolute pressure) corresponding to a condensation temperature of 50°C is 13.19 bar, so the system pressure ratio = 13.19 / 3.75 = 3.52;

[0085] Under low-temperature conditions, the saturated evaporation pressure (absolute pressure) corresponding to a condensation temperature of 12°C is 4.43 bar, so the system pressure ratio = 4.43 / 3.75 = 1.18.

[0086] When enabling the small pressure ratio mode, the condensation temperature usually needs to be more than 3°C higher than the evaporation temperature to maintain a normal thermodynamic cycle. Therefore, it is very necessary to adopt a variable-speed condensation fan and condenser grouping.

[0087] In addition, if the air conditioner is to have a heating (heat pump) function, a four-way reversing valve can be added, etc., to meet the reverse heat pump cycle of the system, which will not be elaborated here.

[0088] As Figure 3 shown is an evolution of the condensation part of the structural schematic diagram of this embodiment. When the cold liquid equipment or air conditioner is used for large-scale refrigeration equipment, for example, the condensation heat exchange capacity corresponding to one compressor is 400 kW, and when the condenser using forced air heat exchange adopts a two-group design, the size will be very large, which is not conducive to modular design. At this time, the condenser can be designed in multiple modules. As Figure 3 shown, in this embodiment, condenser A3.1 and condenser B3.2 can be respectively divided into 2 modules according to specific requirements, and each module is respectively equipped with a condensation fan, thus obtaining a total of 4 condenser modules. The heat exchange capacity of each condenser module is 100 kW. Then, 2 of the condenser modules are connected in parallel and are respectively controlled by the first solenoid valve 2.1 and the second solenoid valve 2.2 at the inlet end. The first solenoid valve 2.1 and the second solenoid valve 2.2 can also be replaced by solenoid valves, and their basic control methods do not conflict with this patent.

[0089] For each group of condensers or each condenser module, the specific internal flow path and process design, fin type and fin pitch, etc. are all designed according to specific circumstances. For large or extra-large cold liquid equipment or air conditioners, such as those with a cooling capacity of 200 kW to 10 MW, multiple sets of systems with the same principle can be adopted to achieve it.

[0090] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. The embodiments described in the present invention are merely descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Among the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without contradiction. As long as such a combination does not violate the idea of the present invention, it should also be regarded as the content disclosed in the present disclosure. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0091] The present invention is not limited to the specific details in the above embodiments. Without departing from the technical concept of the present invention and within the premise of not deviating from the design idea of the present invention, various modifications and improvements made by those skilled in the art to the technical solution of the present invention should fall within the protection scope of the present invention. The technical content claimed by the present invention has been fully recorded in the claims.

Claims

1. A wide-temperature-range refrigeration system with a double evaporator and a double condenser, characterized in that, it includes a compressor, evaporator A, evaporator B, condenser A, condenser B, throttle element A, throttle element B, throttle element C, a liquid receiver, a dryer filter, a sight glass, and a gas-liquid separator, where: the condenser A and condenser B are independent of each other, the condenser A is equipped with a condensing fan A, and the condenser B is equipped with a condensing fan B; the evaporator A and evaporator B are two different heat exchange channels in the same double-circuit heat exchanger for sending cold liquid to cold liquid equipment; or the evaporator A and evaporator B are independent of each other and share an evaporating fan and an air duct for sending cold air for air conditioners; the outlet of the compressor is connected in parallel with 2 pipelines, the first pipeline at the outlet of the compressor is connected to the inlet of the condenser A through a first solenoid valve, the second pipeline at the outlet of the compressor is connected to the inlet of the condenser B through a second solenoid valve, and the outlets of the condenser A and condenser B are merged and then connected to the inlet of the sight glass through the liquid receiver and the dryer filter in sequence; the outlet of the sight glass is connected in parallel with 3 pipelines, the first pipeline at the outlet of the sight glass is connected to the inlet of the throttle element A, the second pipeline at the outlet of the sight glass is connected to the inlet of the throttle element B, the third pipeline at the outlet of the sight glass is connected to the inlet of the throttle element C, and the outlet of the throttle element C is connected in parallel with the inlets of a third solenoid valve, a fourth solenoid valve, and a fifth solenoid valve, where the outlet of the third solenoid valve converges with the outlet of the throttle element A and then is connected to the inlet of the evaporator A, the outlet of the fourth solenoid valve converges with the outlet of the throttle element B and then is connected to the inlet of the evaporator B, and the outlet of the fifth solenoid valve converges with the outlets of the evaporator A and evaporator B and then is connected to the inlet of the gas-liquid separator, and the outlet of the gas-liquid separator is connected to the inlet of the compressor; the gas-liquid separator adopts a double return gas structure; The heat exchange area ratio of the evaporator A to the evaporator B is between 2.5:7.5 and 1:1; the heat exchange area ratio of the condenser A to the condenser B is between 2.5:7.5 and 1:

1.

2. A wide-temperature-range refrigeration system with a double evaporator and a double condenser according to claim 1, characterized in that, when used for air conditioning air supply, the evaporator A, evaporator B, condenser A, and condenser B are all copper tube fin heat exchangers or microchannel heat exchangers.

3. A wide-temperature-range refrigeration system with a double evaporator and a double condenser according to claim 1, characterized in that, The throttle element A, throttle element B, and throttle element C are all electronic expansion valves, or electronic control valves, or solenoid valves, or thermostatic expansion valves.

4. A wide-temperature-range refrigeration system with a double evaporator and a double condenser according to claim 1, characterized in that, The compressor is a variable displacement compressor.

5. A wide-temperature-range refrigeration system with a double evaporator and a double condenser according to claim 1, characterized in that, The condenser A and condenser B are subdivided into several modules, and each module is equipped with a condensing fan when divided into several modules.

6. A wide-temperature-range refrigeration system with a double evaporator and a double condenser according to claim 1, characterized in that, Auxiliary electric heating is respectively provided in the liquid receiver and the gas-liquid separator.

7. A wide-temperature-range refrigeration system with a double evaporator and a double condenser according to claim 1, characterized in that, The first solenoid valve and the second solenoid valve are normally open, and the third solenoid valve, the fourth solenoid valve, and the fifth solenoid valve are normally closed.

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