Low-temperature refrigerating system for high-humidity environment
By incorporating a dehumidifier and solenoid valve into the refrigeration system, combined with a temperature sensor and PID closed-loop regulation, the problems of evaporator frosting and uneven evaporator distribution in high humidity environments are solved, achieving stable cooling performance in high humidity environments.
Patent Information
- Application Number
- CN202423315089.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-12-23
- Estimated Expiration
- 2034-12-31
AI Technical Summary
In high humidity environments, frost formation on the evaporator surface can block air passages, affecting the cooling capacity of the refrigeration system and posing a risk of liquid slugging, which is difficult to effectively address with existing technologies.
A dehumidifier and solenoid valve are installed in the refrigeration system. The refrigerant flow is monitored and controlled by a temperature sensor to ensure uniform distribution between the dehumidifier and the evaporator. Precise control is achieved by using PID closed-loop regulation.
It effectively prevents evaporator frost formation, ensures stable operation of the refrigeration system in high humidity environments, avoids the risk of liquid slugging, and improves refrigeration efficiency and system reliability.
Smart Images
Figure CN223709949U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to environmental test and refrigeration technical field, concretely relates to a low temperature refrigeration system of high humidity environment. BACKGROUND
[0002] The environmental test chamber uses double-stage cascade refrigeration, uses low temperature stage to carry out temperature control to the cabin, and the lowest evaporation temperature of the evaporator is below-70 DEG C. In the high humidity condition of the cabin, the condensate water in the air is gathered on the surface of the evaporator in the cooling process, and the condensate water is attached to the surface of the evaporator heat exchange fin with the reduction of evaporation temperature and forms frost layer, and the frost layer can block the air passage in serious case, so that the evaporator loses the cooling capacity, and the low temperature liquid refrigerant in the evaporator cannot absorb heat, and is still liquid at the outlet of the evaporator, and the compressor has the risk of liquid knock. Thus, the whole refrigeration system is damaged. SUMMARY
[0003] In view of the above-mentioned frost formation problem on the surface of the evaporator in the high humidity condition during cooling, the utility model aims at providing a low temperature refrigeration system of high humidity environment.
[0004] To achieve the utility model's purpose, the technical scheme provided by the utility model is as follows:
[0005] The application provides a low temperature refrigeration system of high humidity environment, which comprises a dehumidifier arranged below a refrigeration evaporator, the dehumidifier is communicated with a cascade refrigeration unit through a refrigerant pipeline, and an electromagnetic valve for controlling the entry of refrigerant is arranged on the refrigerant inlet pipeline, and a temperature sensor for monitoring the outlet temperature of the dehumidifier is arranged on the refrigerant outlet pipeline; the temperature sensor for collecting the temperature in the box body is arranged in the environmental test chamber.
[0006] Further, the dehumidifier is a dehumidification coil.
[0007] Further, when a plurality of evaporators are connected in parallel, an electromagnetic valve is arranged at the inlet of each evaporator, and a temperature sensor is arranged at the refrigerant outlet of each evaporator, and the opening and closing frequency of the electromagnetic valve at the inlet is controlled according to the outlet temperature.
[0008] Compared with the prior art, the utility model has the beneficial effects as follows:
[0009] Firstly, most of the water vapor in the humid air is removed through the dehumidification coil, the temperature of the temperature sensor installed at the outlet of the dehumidification coil is compared with the actual temperature of the box body, the opening frequency of the electromagnetic valve at the inlet of the dehumidification coil is controlled, and the surface temperature of the dehumidification coil is controlled; through the above scheme, the frost formation problem on the surface of the evaporator during cooling in the high humidity condition can be solved;
[0010] In addition, when multiple evaporators are connected in parallel for refrigeration, a solenoid valve is installed on the liquid inlet pipe of each evaporator, and a temperature sensor is installed at the outlet of each evaporator. During refrigeration operation, the controller collects the temperatures from the temperature sensors installed at the outlets of each evaporator, compares them, and controls the opening frequency of each solenoid valve to achieve a more uniform liquid inlet flow to each evaporator. This solution can solve the problem of uneven refrigerant distribution when multiple evaporators are connected in parallel. Attached Figure Description
[0011] Figure 1 This is a first schematic diagram of the system structure provided in an embodiment of this application;
[0012] Figure 2 This is a second schematic diagram of the system structure adopted in the embodiments of this application. Detailed Implementation
[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0014] Example 1
[0015] like Figure 1 As shown, this application provides a low-temperature refrigeration system for high-humidity environments, including a dehumidifier installed below a refrigeration evaporator. The dehumidifier is connected to a cascade refrigeration unit via a refrigerant pipeline, and a solenoid valve for controlling the refrigerant inflow is installed on the refrigerant inlet pipeline. A temperature sensor for monitoring the dehumidifier outlet temperature is installed on the refrigeration outlet pipeline. The system also includes a chamber temperature sensor installed inside an environmental test chamber to collect the temperature inside the chamber. The dehumidifier is a dehumidification coil.
[0016] It should be noted that the system removes most of the water vapor from the humid air through the dehumidification coil. This is achieved by comparing the temperature of the temperature sensor installed at the outlet of the dehumidification coil with the actual temperature of the enclosure, and controlling the opening frequency of the solenoid valve at the refrigerant inlet of the dehumidification coil, thereby controlling the surface temperature of the dehumidification coil. After the cooling operation begins, when the temperature inside the enclosure is above 0°C, the surface temperature of the dehumidification coil can be controlled to be lower than the dew point temperature of the ambient air in the enclosure. This causes water molecules to condense rapidly on the dehumidification coil as the air circulates, eventually forming water droplets that fall into the water collection tray at the bottom of the dehumidification coil and are discharged from the enclosure through the drainage system. Once the temperature inside the enclosure drops below 0°C, the system can automatically determine whether to continue opening the solenoid valve of the dehumidification coil based on the humidity level inside the enclosure.
[0017] The thickness of the frost layer on the surface of the dehumidification coil is 4mm. The total surface area of the coil can satisfy the frost amount of more than 90% of the air humidity in the test chamber under the worst working condition. The minimum temperature of the refrigerant in the coil is above -70℃. The dew point temperature of the air after dehumidification can be reduced to -70℃. Most of the water vapor in the air is removed by the dehumidification coil. The surface temperature of the dehumidification coil can be controlled by controlling the opening degree of the valve at the inlet of the refrigerant, and the dew point temperature of the air can be reduced to a minimum of -70℃. The water content in the air after dehumidification is very low, and the frost layer on the surface of the evaporator is very thin and does not affect its refrigeration performance.
[0018] Example 2
[0019] As Figure 2 shown, when the environmental test chamber is large, multiple evaporators are sometimes used for refrigeration. Due to the influence of factors such as piping and air volume, the distribution of refrigerant in each evaporator will be different, and the refrigerant in the evaporator with more distribution cannot be fully vaporized, and the outlet is in a liquid state. The evaporator with less refrigerant distribution has a higher outlet superheat, thereby greatly reducing the refrigeration capacity of the entire system.
[0020] To solve the problem of uneven distribution of multiple evaporators by controlling the system. When multiple evaporators are connected in parallel, an electromagnetic valve is provided at the inlet of each evaporator, and a temperature sensor is provided at the refrigerant outlet of each evaporator. The opening and closing frequency of the electromagnetic valve at the inlet is controlled according to the outlet temperature. When the refrigerant is unevenly distributed, the temperature of the refrigerant outlet of each evaporator will be different. The refrigerant with lower temperature is over-distributed, and the refrigerant with higher temperature is under-distributed. The opening and closing frequency of the electromagnetic valve at the inlet is controlled according to the outlet temperature, so that the outlet temperature of each evaporator tends to be the same. This can effectively ensure that the refrigerant in each evaporator is evenly distributed, and the refrigeration system can achieve the best refrigeration performance.
[0021] It should be noted that the control process of the system to solve the problem of uneven distribution of multiple evaporators under high humidity conditions and cooling and frosting is realized by PID closed-loop adjustment of the electromagnetic valve. The system control uses Siemens 6ES7510-1DK03-0AB0 PLC as the main controller. The temperature value is collected by the analog input module 6ES7134-6JD00-0CA1, and the main PLC performs main logic operation. Through PID operation, the dehumidification valve, refrigeration valve and other actuators are controlled to ensure that the temperature and humidity can reach and maintain the set value. PID regulation control is a traditional control method, which is applicable to temperature, pressure, flow, liquid level and almost all fields. Different fields only need to set different PID parameters. As long as the parameters are set properly, good results can be achieved. The control requirements can reach 0.1% or even higher. The classical PID algorithm is mainly used for regulation during the temperature control process in the chamber.
[0022] It should be noted that the present application does not involve method innovation, and the electronic components designed are all obtained by outsourcing, and the schemes not described in detail in the present application all adopt existing technologies.
[0023] Finally, it should be noted that the above embodiments are only used to illustrate and describe the present application, and are not intended to limit the present application to the scope of the described embodiments. In addition, those skilled in the art can understand that the present application is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present application, and these variations and modifications all fall within the scope of the present application.
Claims
1. A low-temperature refrigeration system for high-humidity environments, characterized in that, The system includes a dehumidifier located below the evaporator, which is connected to the cascade refrigeration unit via a refrigerant pipeline. The refrigerant inlet pipeline is equipped with a solenoid valve for controlling the refrigerant inlet, and the refrigeration outlet pipeline is equipped with a temperature sensor for monitoring the dehumidifier outlet temperature. The system also includes a chamber temperature sensor located inside the environmental test chamber to collect the temperature inside the chamber.
2. The low-temperature refrigeration system for high humidity environments according to claim 1, characterized in that, The dehumidifier is a dehumidification coil.
3. The low-temperature refrigeration system for high humidity environments according to claim 1, characterized in that, When multiple evaporators are connected in parallel, a solenoid valve is installed at the inlet of each evaporator, and a temperature sensor is installed at the refrigerant outlet of each evaporator. The opening and closing frequency of the solenoid valve at the inlet is controlled according to the outlet temperature.