Energy-saving cascade refrigeration system
By using high-temperature and low-temperature refrigeration modules connected in series with air-cooled and water-cooled condensers, combined with liquid circuit switching and environmental compensation modules, the problem of unstable operation of cascade refrigeration systems in high-temperature and low-temperature environments is solved, achieving high efficiency, energy saving and precise temperature control, and is suitable for vehicle-mounted equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINESE PEOPLES LIBERATION ARMY UNIT 63867
- Filing Date
- 2025-06-23
- Publication Date
- 2026-07-03
AI Technical Summary
Existing cascade refrigeration systems are unstable in high and low temperature environments, resulting in abnormal pressure, excessive energy consumption, and insufficient temperature control accuracy, making it difficult to meet the needs of precision testing.
It adopts high-temperature and low-temperature refrigeration modules with air-cooled and water-cooled condensers connected in series, and dynamically adjusts the refrigeration mode through liquid circuit switching valve group and environmental compensation module. Combined with VRF technology, it can accurately adjust the refrigerant flow and realize the switching between single-stage and cascade refrigeration modes. It is equipped with gas-liquid bypass valve to protect the compressor.
It achieves stable operation in complex environments, reduces energy consumption by more than 40%, improves temperature control accuracy to ±0.5℃, and reduces system failure rate by 80%, making it suitable for harsh scenarios such as vehicle-mounted applications.
Smart Images
Figure CN224454954U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of refrigeration equipment technology, specifically relating to an energy-saving cascade refrigeration system. Background Technology
[0002] Currently, in the field of actual environmental testing, cascade refrigeration systems are often used to produce temperatures below -40℃. Cascade refrigeration systems circulate and condense the low-temperature refrigerant in the high-temperature stage, and then the low-temperature evaporator achieves ultra-low temperature refrigeration of -40℃ to -150℃, which is widely used in vehicle-mounted insulated conveying equipment. However, existing technologies have significant drawbacks: First, they have poor environmental adaptability. When operating in high-temperature environments (>35℃), the pressure of the entire refrigeration system increases, and the condensing pressure exceeds 20 bar, resulting in a decrease in refrigeration capacity. When the condensing temperature is too high, the system may even fail to cool down and frequently experience overpressure alarms and shutdowns. In low-temperature environments (<-20℃), due to the overall low pressure of the refrigeration system, the condensing pressure is only maintained at 5~6 bar. The condenser condenses and liquefies prematurely, causing a reduction in the high and low pressure differential and insufficient refrigerant flow, leading to underpressure faults. Second, energy consumption is too high in the ambient temperature range. When producing temperatures from -10℃ to +15℃, there is an excess of refrigeration capacity, requiring electric heating to balance it. Moreover, with both compressor stages running simultaneously, ineffective energy consumption exceeds 60%. Third, the temperature control accuracy is insufficient, with temperature fluctuations exceeding ±2℃, making it difficult to meet the requirements of precision testing.
[0003] Although there are improved solutions using water-cooled condensers, they still cannot dynamically respond to changes in ambient temperature, and the system architecture remains unchanged, so the energy consumption problem in the normal temperature range is not solved. Utility Model Content
[0004] To overcome the above shortcomings, this utility model provides an energy-saving cascade refrigeration system.
[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0006] An energy-saving cascade refrigeration system includes a high-temperature stage refrigeration module and a low-temperature stage refrigeration module cascaded through an evaporator-condenser. The high-temperature stage refrigeration module condenses the low-temperature stage refrigeration module through the evaporator-condenser. The low-temperature stage refrigeration module has an in-box evaporator located within the space requiring refrigeration. The high-temperature stage refrigeration module has an in-box evaporator located within the space requiring refrigeration and connected in parallel with the evaporator-condenser. The inlet pipes of the high-temperature stage evaporator and the evaporator-condenser are equipped with a liquid path switching valve group. The liquid path switching valve group is used to cut off the passage between the evaporator-condenser and the high-temperature stage refrigeration module compressor in low-cooling-capacity mode, allowing single-stage refrigeration by the high-temperature stage in-box evaporator. In high-cooling-capacity mode, it cuts off the passage between the high-temperature stage in-box evaporator and the high-temperature stage refrigeration module compressor, forming cascade refrigeration through the evaporator-condenser and the low-temperature stage refrigeration module.
[0007] Further optimization includes the inclusion of a series-connected air-cooled condenser and a water-cooled condenser in both the high-temperature stage refrigeration module and the low-temperature stage refrigeration module, with the water-cooled condenser equipped with a water source interface.
[0008] In a further optimization, the water-cooled condenser is connected in series downstream of the air-cooled condenser. The compressor exhaust from both the high-temperature stage refrigeration module and the low-temperature stage refrigeration module is pre-cooled by the air-cooled condenser and then further cooled by the water-cooled condenser. The water-cooled condenser is connected to the water source via a solenoid valve, which is used to start water supply when the ambient temperature is greater than 30°C or the condensing pressure is greater than 18MPa.
[0009] Further optimization also includes an environmental compensation module, which includes an electric heater, a fan speed controller, and a pressure sensor installed in the air-cooled condenser of the high-temperature refrigeration module. The pressure sensor is installed in the outlet pipe of the air-cooled condenser and is electrically connected to the solenoid valves of the electric heater, the fan speed controller, and the water source interface.
[0010] Further optimizations include a control module, whose output is electrically connected to a liquid circuit switching valve group, used to control the high-temperature stage refrigeration module, the low-temperature stage refrigeration module and the liquid circuit switching valve group to adjust the refrigeration working mode of the system.
[0011] Further optimization involves the high-temperature stage evaporator being a finned tube structure, forming an independent circuit with the high-temperature stage refrigeration module's throttling valve, compressor, air-cooled condenser, and water-cooled condenser.
[0012] Beneficial effects:
[0013] 1. This invention effectively solves the problems of excessively high condensing pressure and reduced cooling efficiency in traditional vehicle refrigeration systems under high-temperature environments by connecting an air-cooled condenser and a water-cooled condenser in series. In the high temperatures of summer, the introduction of the water-cooled condenser can significantly reduce the condensing temperature and prevent the system from shutting down due to overpressure. In the low temperatures of winter, the condensing pressure is regulated by electric heaters and fan speed control to ensure stable operation. At the same time, the dual evaporator design realizes temperature zone control. When the set temperature is ≥-10℃, only the high-temperature stage single-stage refrigeration is activated, which reduces energy consumption by more than 40% compared with the traditional cascade system and greatly improves energy utilization efficiency.
[0014] 2. Employing VRF technology and multi-mode automatic switching logic, the system can dynamically adjust the refrigerant flow and operating mode according to ambient temperature and set requirements, improving temperature control accuracy by ±0.5℃. In addition, the coordinated operation of the gas-liquid bypass valve and pressure sensor avoids compressor failures caused by abnormal suction pressure, reducing the system alarm rate by 80%. It can operate stably in complex environments (-30℃ to +50℃), making it particularly suitable for harsh scenarios such as vehicle and mobile devices. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of a cascade refrigeration system with a dual condenser.
[0016] Figure 2 This is a schematic diagram of a cascade refrigeration system with two evaporators.
[0017] Figure 3 This is a schematic diagram of the cascade refrigeration system of this utility model;
[0018] Attached reference numerals: 1. Air-cooled condenser; 2. Water-cooled condenser; 3. High-temperature stage in-chamber evaporator; 4. High-temperature stage evaporative condenser; 5. Fan speed controller; 6. Low-temperature stage in-chamber evaporator; 7. Liquid bypass solenoid valve; 8. Gas bypass solenoid valve; 9. Pulse solenoid valve. Detailed Implementation
[0019] In order to better understand the above-mentioned objectives, features and advantages of this utility model, the present utility model will be described in detail below with reference to specific embodiments. The following embodiments are implemented based on the technical solution of this utility model, and detailed implementation methods and specific operation processes are given. However, this utility model can also be implemented in other ways different from those described herein. Therefore, the protection scope of this utility model is not limited to the following embodiments.
[0020] An energy-saving cascade refrigeration system includes a high-temperature stage refrigeration module, a low-temperature stage refrigeration module, a dual evaporator module, and an environmental compensation module. The high-temperature stage refrigeration module and the low-temperature stage refrigeration module are cascaded through a high-temperature stage evaporator condenser 4. Both the high-temperature stage refrigeration cycle and the low-temperature stage refrigeration cycle include a series air-cooled condenser 1 and a water-cooled condenser 2. The water-cooled condenser 2 is equipped with a quick water supply interface. The air-cooled condenser 1 is an oxygen-free copper coil with sinusoidal corrugated aluminum fins. The water-cooled condenser 2 is a shell-and-tube water condenser or a plate heat exchanger. The water-cooled condenser 2 is connected in series downstream of the air-cooled condenser 1. The compressor exhaust of both the high-temperature stage refrigeration module and the low-temperature stage refrigeration module is pre-cooled by the air-cooled condenser 1 and then deeply re-cooled by the water-cooled condenser 2.
[0021] When the ambient temperature is low, air-cooled condenser 1 is used for condensation, and water-cooled condenser 2 does not supply water. When the ambient temperature is high, air-cooled condenser 1 cannot meet the requirements, so water is supplied to the equipment through a quick water source interface to ensure that air-cooled condenser 1 and water-cooled condenser 2 work at the same time. This can ensure a relatively stable condensation temperature of the refrigeration system, thereby improving the refrigeration efficiency of the refrigeration equipment and achieving the purpose of rapid cooling of the environment in summer.
[0022] This invention employs a high-temperature stage refrigeration module connected in parallel with the dual evaporator module. The dual evaporator module includes a high-temperature stage in-box evaporator 3 and a high-temperature stage evaporative condenser 4. The inlet and outlet of the high-temperature stage in-box evaporator 3 are connected to the outlet of the high-temperature stage throttling valve and the suction port of the high-temperature stage compressor, respectively. The high-temperature stage in-box evaporator 3 forms an independent circuit with the throttling valve, compressor, air-cooled condenser, and water-cooled condenser of the high-temperature stage refrigeration module. When the set temperature is ≥-10℃, the single-machine refrigeration system automatically starts, using the high-temperature stage in-box evaporator 3 for cooling and disconnecting the parallel-connected high-temperature stage evaporative condenser 4. Simultaneously, the low-temperature stage refrigeration module does not start, and its in-box evaporator also stops working, thereby achieving energy saving and consumption reduction. When the set temperature is <-10℃, the cascade refrigeration system is automatically started, cutting off the high-temperature stage evaporator 3 in the high-temperature stage refrigeration module and starting the high-temperature stage evaporator condenser 4 connected in parallel to it to condense the low-temperature stage refrigeration module, and then cooling down through the low-temperature stage evaporator 6 in the low-temperature stage refrigeration module. The inlet pipes of the high-temperature stage evaporator 3 and the high-temperature stage evaporator condenser 4 are equipped with liquid path switching valve groups. The liquid path switching valve groups are used to cut off the passage of the high-temperature stage evaporator condenser 4 when the high-temperature stage evaporator 3 is started, and cut off the passage of the high-temperature stage evaporator 3 when the high-temperature stage evaporator condenser 4 is started.
[0023] This invention also includes an environmental compensation module and a control module. The environmental compensation module includes an electric heater, a fan speed controller 5, and a pressure sensor installed in the air-cooled condenser 1 of the high-temperature stage refrigeration module. The pressure sensor is installed in the outlet pipe of the air-cooled condenser 1 and is electrically connected to the electric heater, the fan speed controller 5, and the solenoid valve of the rapid water supply interface. The output of the control module is electrically connected to a liquid circuit switching valve group. The control module and the liquid circuit switching valve group work together to adjust the condensing operation mode of the system.
[0024] a. When the set temperature is ≥-10℃, the high-temperature stage evaporator 3 is activated, the liquid circuit switching valve group cuts off the high-temperature stage evaporator-condenser 4 passage, and the low-temperature stage refrigeration module is turned off to achieve single-stage refrigeration mode.
[0025] b. When the set temperature is <-10℃, the high-temperature stage evaporator condenser 4 is activated, the liquid circuit switching valve group cuts off the passage of the high-temperature stage evaporator 3 in the box, and the low-temperature stage refrigeration module is started to realize the cascade refrigeration mode.
[0026] This invention employs VRF (Variable Refrigerant Flow) refrigeration regulation technology. Pulse solenoid valves 9 are installed before the high-temperature stage evaporator 3 of the high-temperature stage refrigeration module and the low-temperature stage evaporator 6 of the low-temperature stage refrigeration module. These pulse solenoid valves 9 automatically regulate the refrigerant flow of the high-temperature and low-temperature stage refrigeration modules, reducing their operating power to approximately half, significantly improving temperature control accuracy and reducing energy consumption. Liquid bypass solenoid valves 7 and gas bypass solenoid valves 8 are installed in the circulation paths of both the high-temperature and low-temperature stage refrigeration modules. These valves regulate the gas supply to the two compressor stages, respectively, to protect the compressors and maintain normal suction pressure and temperature.
[0027] The working control process of this invention is as follows:
[0028] After the system starts up, the control module first detects the ambient temperature and the values of each pressure sensor, and then automatically selects the operating mode according to the user-set temperature.
[0029] When the set temperature is ≥-10℃, it enters the single-stage refrigeration mode. At this time, only the high-temperature stage refrigeration module is activated. After the refrigerant is cooled by the air-cooled condenser 1 and water-cooled condenser 2 of the high-temperature stage refrigeration module, it is refrigerated through the evaporator 3 in the high-temperature stage chamber.
[0030] When the set temperature is <-10℃, the cascade refrigeration mode is entered, and the high and low temperature stage refrigeration cycles are started simultaneously. The high temperature stage cycle provides condensation conditions for the low temperature stage refrigeration module through the high temperature stage evaporator condenser 4.
[0031] When the single-stage cooling mode is activated, the environmental compensation module uses an electric heater and a fan speed controller to handle extreme operating conditions.
[0032] During high summer temperatures (ambient temperature ≥30℃ or pressure ≥1.8MPa), the water-cooled condenser 2 of the high-temperature stage refrigeration module is activated, and the water-cooled condenser 2 of the low-temperature stage refrigeration module also operates simultaneously.
[0033] In winter, when the temperature is low (ambient temperature ≤ -20℃ or pressure ≤ 0.8MPa), first reduce the speed of the fan speed controller 5 and start the high-temperature electric heater to increase the condensing pressure.
[0034] When the cascade cooling mode is activated, the environmental compensation module uses an electric heater and a fan speed controller to handle extreme operating conditions.
[0035] During high summer temperatures (ambient temperature ≥30℃ or pressure ≥1.8MPa), the water-cooled condenser 2 of both the high-temperature stage refrigeration module and the low-temperature stage refrigeration module is turned on simultaneously, and the dual-stage water cooling works in tandem.
[0036] In winter, when the temperature is low (ambient temperature ≤ -20℃ or pressure ≤ 0.8MPa), the electric heaters of both the high-temperature stage refrigeration module and the low-temperature stage refrigeration module are started simultaneously, and the fan speed controller 5 speed is reduced.
[0037] The system uses VRF technology to precisely regulate the refrigerant flow through a pulse solenoid valve, and works with liquid bypass solenoid valve 7 or gas bypass solenoid valve 8 to protect the compressor, achieving a temperature control accuracy of ±0.5℃. Multiple safety protection mechanisms ensure stable operation of the system under various environmental conditions.
[0038] The foregoing has shown and described the main features, usage method, basic principles, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model based on actual circumstances without departing from its spirit and scope. All such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.
Claims
1. An energy-saving cascade refrigeration system, comprising a high-temperature stage refrigeration module and a low-temperature stage refrigeration module cascaded through an evaporator-condenser (4), wherein the high-temperature stage refrigeration module condenses the low-temperature stage refrigeration module through the evaporator-condenser (4), and the low-temperature stage evaporator (6) of the low-temperature stage refrigeration module is disposed in the space requiring refrigeration, characterized in that: The high-temperature stage refrigeration module is equipped with a high-temperature stage in-box evaporator (3), which is located in the space that needs to be refrigerated and is connected in parallel with the evaporator condenser (4). The inlet pipes of the high-temperature stage in-box evaporator (3) and the evaporator condenser (4) are equipped with a liquid circuit switching valve group. The liquid circuit switching valve group is used to cut off the passage between the evaporator condenser (4) and the high-temperature stage refrigeration module compressor in the low-cooling capacity mode, so that the high-temperature stage in-box evaporator (3) forms a single-stage refrigeration, and cut off the passage between the high-temperature stage in-box evaporator (3) and the high-temperature stage refrigeration module compressor in the high-cooling capacity mode, so that the evaporator condenser (4) and the low-temperature stage refrigeration module form a cascade refrigeration.
2. The energy-efficient cascade refrigeration system of claim 1, wherein: Both the high-temperature stage refrigeration module and the low-temperature stage refrigeration module include a series air-cooled condenser (1) and a water-cooled condenser (2), with the water-cooled condenser (2) equipped with a water source interface.
3. The energy-efficient cascade refrigeration system of claim 2, wherein, The water-cooled condenser (2) is connected in series downstream of the air-cooled condenser (1). The exhaust from the compressors of the high-temperature stage refrigeration module and the low-temperature stage refrigeration module is pre-cooled by the air-cooled condenser (1) and then deeply re-cooled by the water-cooled condenser (2). The water-cooled condenser (2) is connected to the water source through a solenoid valve. The solenoid valve is used to start water supply when the ambient temperature is greater than 30°C or the condensing pressure is greater than 18MPa.
4. The energy-efficient cascade refrigeration system of claim 1, wherein, It also includes an environmental compensation module, which includes an electric heater, a fan speed controller (5) and a pressure sensor installed in the air-cooled condenser (1) of the high-temperature refrigeration module. The pressure sensor is installed in the outlet pipe of the air-cooled condenser (1) and is electrically connected to the solenoid valve of the electric heater, the fan speed controller (5) and the water source interface.
5. The energy-efficient cascade refrigeration system of claim 1, wherein, It also includes a control module, whose output is electrically connected to the liquid circuit switching valve group, which is used to control the high-temperature stage refrigeration module, the low-temperature stage refrigeration module and the gas-liquid circuit switching valve group to adjust the refrigeration working mode of the system.
6. The energy-efficient cascade refrigeration system of claim 3, wherein, The high-temperature stage evaporator (3) is a finned tube structure, forming an independent circuit with the high-temperature stage refrigeration module's throttle valve, compressor, air-cooled condenser, and water-cooled condenser.