Operating Instructions for Hot Fluorine Defrosting Air Coolers (Evaporators)

Unlike the previous two defrosting methods—water defrosting and electric defrosting—Hot Fluorine Defrosting air coolers (evaporators) are a type of air cooler (Evaporator) that adopts hot working fluid defrosting technology. They melt the frost layer on the surface of the evaporator by utilizing the high-temperature superheated refrigerant discharged from the compressor. This technology temporarily converts the evaporator into a condenser, using the heat released during the condensation of the hot working fluid to melt the frost layer. At the same time, the refrigerant and lubricating oil previously accumulated in the evaporator are discharged into a defrost collection tank or a low-pressure circulation tank under the pressure of the hot medium or solely by gravity, enabling efficient recovery and reuse.

Basic Structure and Working Principle

• On the basis of the original air cooler (evaporator), the Hot Fluorine Defrostingair cooler (evaporator) is equipped with an additional Hot Fluorine Defrosting This system mainly consists of components such as a compressor, an oil separator, a defrost solenoid valve, and a defrost liquid discharge barrel.
• Working Principle: The hot Freon vapor discharged from the Compressoris used to heat and defrost the air cooler (evaporator). The thawed Freon liquid enters the liquid discharge tank, which is then pressurized. This pressurization allows the Freon in the liquid discharge tank to be supplied to the liquid supply pipe for refrigeration. During defrosting, the flow direction of the discharged liquid is consistent with that in the refrigeration cycle. (As shown in the figure: )

1. Compressor 2. Condenser 3. Liquid Discharge Barrel 4. Evaporator 5. Main Defrost Solenoid Valve 6. Defrost Solenoid Valve 7. Liquid Supply Solenoid Valve 8. Return Air Solenoid Valve 9. Liquid Return Solenoid Valve 10. Liquid Discharge Solenoid Valve 11. Pressure Reduction Solenoid Valve 12. Pressurization Solenoid Valve 13. Liquid Drainage Solenoid Valve

Types of YSHT Hot Fluorine Defrosting Air Coolers (Evaporators) and Their Applications in Cold Storage

1. HT-RD Series: Suitable for cold storage at approximately -18°C, it is commonly used in scenarios such as food refrigeration(e.g., short-term storage of meat, fruits, and vegetables) and cool storage of pharmaceuticals. It ensures that stored items maintain their quality in a suitable low-temperature environment.
2. HT-RJ Series: Applicable to quick-freezing cold storage at -25°C, it is mainly used in food quick-freezing processing(e.g., quick-frozen dumplings, quick-frozen meat) and low-temperature preservation of biological samples. It rapidly lowers the temperature of items to lock in nutrients or ensure the activity of samples.
3. HT-RL Series: Designed for fresh-keeping cold storage at around 0°C, it is widely used in fresh-keeping of fruits and vegetables, storage of fresh flowers, and short-term storage of dairy products. While maintaining the freshness of items, it prevents damage caused by low temperatures.

1. Advantages of the Hot Fluorine Defrosting System Compared with Water Defrosting and Electric Defrosting

Core Advantages

1. High Defrosting Efficiency: Hot Fluorine Defrostingdirectly uses the high-temperature refrigerant gas from the refrigeration system itself, such as the compressor The heat transfer is direct without intermediate losses, allowing the frost layer to melt quickly from the inside. Typically, Hot Fluorine Defrosting can be completed within 10-30 minutes, while electric defrosting for a thick frost layer takes 40-90 minutes and water defrosting for a thick frost layer requires 30-60 minutes.
2. Low Energy Consumption and Cost: The heat source for Hot Fluorine Defrostingcomes from the waste heat of the refrigeration system itself. The discharge temperature of the compressor usually reaches 70-120°C, and this heat would otherwise be wasted through heat dissipation via the condenser. Hot Fluorine Defrosting requires almost no additional energy consumption, only a small amount of electrical energy to drive the valve switching. Its operating cost is only 1/5 to 1/3 of that of electric defrosting.
3. Good Protection for Equipment: During the Hot Fluorine Defrostingprocess, the surface temperature of the evaporator is uniform, approximately 5-15°C, without local high or low-temperature shocks. This avoids pressure cracking of the evaporator copper tubes due to sudden temperature changes and prevents ice blockage caused by uneven melting of the frost layer, thereby extending the service life of the equipment. In contrast, electric defrosting may cause local dry burning, leading to burnout of the heating tube or local overheating and deformation of the evaporator. For water defrosting, if the water source contains impurities, it is easy to block the fin gaps, and in low-temperature environments, undrained water can easily freeze and crack the pipes.
4. High Safety Factor: During electric defrosting, the electric heating wire can reach a temperature of several hundred degrees Celsius when energized for a long time. If the temperature control or time control components are damaged, continuous heating will occur, which is highly likely to cause a fire. Hot Fluorine Defrostingis regulated based on the condensation temperature, and the temperature is generally several tens of degrees Celsius, far below the ignition point, fundamentally eliminating the possibility of fire.
5. Strong Environmental Adaptability: Hot Fluorine Defrostingis suitable for low-temperature and ultra-low-temperature environments, such as quick-freezing cold storage below -40°C. The high-temperature refrigerant gas can stably release heat in low-temperature conditions without the risk of freezing. Moreover, it does not require an external water source and can operate stably in water-scarce or frigid areas. In contrast, water defrosting is not suitable for environments below -19°C and relies on a stable water supply, so its application is limited in arid and high-altitude areas.
6. Easy Operation and Maintenance: Hot Fluorine Defrostingcan achieve fully automatic defrosting through solenoid valves and controllers, triggered by the frost layer thickness or operating time, without manual intervention. Its system is usually simple to operate, does not require an additional power supply, reducing installation complexity and maintenance costs. There are no vulnerable components such as heating tubes and water pumps, and maintenance only requires regular inspection of valve tightness.

Additional Advantage: System Synergy

During the operation of the refrigeration system, the high-temperature refrigerant gas (waste heat) discharged from the compressor would normally need to be cooled by the condenser before circulation. Hot Fluorine Defrosting directly recycles and utilizes this "waste heat" for defrosting. This not only reduces the heat dissipation load of the condenser (indirectly lowering the energy consumption of the condenser fan/water pump) but also realizes "secondary energy utilization", thereby improving the overall coefficient of performance (COP) of the refrigeration system. This is an advantage that water defrosting and electric defrosting (both requiring "additional energy consumption") cannot achieve.

2. Precautions for Using Hot Fluorine Defrosting Air Coolers (Evaporators)

As equipment that relies on the waste heat of the refrigeration system for defrosting, the performance and safety of Hot Fluorine Defrosting air coolers (evaporators) are highly dependent on "system collaborative control" and "regular maintenance". The following precautions cover system commissioning, operation monitoring, maintenance, safety protection, and other aspects:

Initial Start-Up and System Commissioning: Ensure "Collaborative Adaptation" to Avoid Initial Failures

1. Confirm the Adaptability of Pipes and Valves

The core of Hot Fluorine Defrosting is the entry of high-temperature refrigerant gas (compressor discharge) into the air cooler（evaporator）. First, it is necessary to check the sealing of the refrigerant pipe connections (such as flanges and welding points) to prevent high-pressure gas leakage. At the same time, confirm that the models of the solenoid valves and check valves in the defrost circuit are compatible with the system (e.g., the pressure resistance must meet the compressor discharge pressure, usually ≥2.5MPa) to prevent the defrost circuit from being unable to switch on or off due to valve jamming.

2. Set Reasonable Defrost Parameters

Based on the application scenario of the air cooler (evaporator) (such as cold storage temperature and frost layer formation speed), set the defrost trigger conditions and operating duration through the controller.

• Trigger Conditions: Priority is given to triggering based on the "frost layer thickness sensor signal" (more accurate). If there is no sensor, it can be triggered based on the "operating time" (e.g., once every 4-8 hours, which can be appropriately extended for low-temperature cold storage).
• Operating Duration: The single defrost time should be controlled within 10-30 minutes (adjusted according to the frost layer thickness). Avoid excessively long defrost time, which would cause the temperature of the air cooler （evaporator）to be too high (exceeding 20°C) and instead increase the subsequent refrigeration load. Also, avoid excessively short defrost time, which would result in incomplete defrosting and residual frost layers.
• No-Load Test of the Defrost Cycle

Before the initial start-up, disconnect the refrigeration circuit of the air cooler (evaporator) and test the defrost process independently: After starting the compressor, observe whether the solenoid valve opens on time, whether the high-temperature gas enters the evaporator normally, and whether it can automatically switch back to the refrigeration circuit after defrosting. Ensure that the "defrost-refrigeration" switch is smooth to avoid compressor pressure buildup or liquid return.

Daily Operation Monitoring: Focus on "Abnormal Conditions" and Intervene in a Timely Manner

Real-Time Monitoring of Key Indicators During Defrosting

During operation, observe the core parameters through the instrument panel or controller, and shut down the equipment immediately for inspection if abnormalities are found.

Avoid "Invalid Defrosting" or "Excessive Defrosting"

• Forcibly defrosting when there is "no frost or a thin frost layer" is prohibited: At this time, the high-temperature gas will only heat the evaporator, which not only wastes energy but also may cause an abnormal increase in the cold storage temperature, affecting the quality of stored goods.
• If the temperature at the air outlet of the air cooler (evaporator) is still lower than the normal refrigeration temperature after defrosting (e.g., the air outlet temperature of the low-temperature cold storage is lower than -25°C accompanied by reduced air flow), it is necessary to check for "secondary freezing" (e.g., defrost water not discharged in time and re-freezing on the evaporator surface) and clean the drainage port in a timely manner.

3.Regular Maintenance: Extend Equipment Service Life and Avoid Scaling/Clogging

1. Cleaning of the Defrost Circuit: Prevent Impurity Clogging
2. Maintenance of Valves and Sensors: Ensure Accurate Signals
3. Inspection of the Drainage System: Prevent Defrost Water from Freezing

4.Safety Protection: Avoid High-Pressure and High-Temperature Risks

• Protection of High-Pressure Pipes

The refrigerant pipes in the Hot Fluorine Defrosting circuit are high-pressure pipes (with a pressure up to 1.5-2.0MPa). Collision or extrusion should be avoided. The exterior of the pipes should be wrapped with thermal insulation layers to prevent personnel from being scalded by touching the high-temperature pipes (the discharge temperature can reach 70-120°C).

• Electrical Safety

The electrical components of the defrost system (solenoid valves, controllers, and heat tracing cables) must comply with explosion-proof/moisture-proof standards (especially for high-humidity cold storage). It is prohibited to open the access door of the air cooler (evaporator) during defrost operation. If live maintenance is required, the compressor power supply must be disconnected first, and the pressure in the defrost circuit must be released (slowly releasing pressure through the pressure relief valve) to prevent injury from high-pressure gas injection.

• Emergency Shutdown Plan

If emergency situations such as "pipe leakage (detecting the odor of refrigerant), abnormal compressor noise, or sudden increase in defrost temperature" occur during operation, the main shutdown button must be pressed immediately to turn off the compressor and the valves in the defrost circuit. After the system pressure drops to atmospheric pressure, troubleshooting can be carried out. Disassembling the pipes under high-pressure conditions is prohibited.