Prefabricated vegetable cold storage supporting compression condensing unit | Load accounting and start stop protection setting scheme
The storage temperature of prefabricated vegetable cold storage is mostly controlled at -18 ℃, and the system allows a temperature deviation of ± 1 ℃. The unit capacity cooling load value is 160-230W/m ³, which is suitable for using semi closed piston compression condensing units.
The frequency of pre packaged food entering and leaving the warehouse is high, with doors opening up to 18 times a day or more. The heat invasion load accounts for 32% of the total cooling load. When selecting, it is recommended to increase the cooling capacity margin by 20% to avoid continuous full load operation of the unit.
The semi enclosed models of Xitelide medium four cylinder and large four cylinder are often equipped with pre packaged vegetable project compression condensing units. R404A is preferred as the refrigerant, and the heat exchange stability under low temperature conditions is about 6% better than R507.
The compression condensing unit comes with an oil separation and liquid storage structure, which reduces on-site pipeline welding by 45% compared to split compressors. It is suitable for rapid installation and commissioning in central kitchens and prefabricated vegetable processing plants.
Low suction pressure of the compressor is a high-frequency fault in prefabricated vegetable cold storage, mostly caused by excessive frost on the evaporator. When the frost layer thickness exceeds 3mm, the heat transfer efficiency decreases by 38% and the return air capacity continues to decline.
The operating current of the unit needs to be matched with the power supply system. Under Southeast Asian 415V/50Hz operating conditions, the rated current of the same model is 7% lower than the domestic 380V version. During debugging, domestic parameters cannot be directly applied.
Prefabricated vegetable cold storage has a low tolerance for shutdown risks, and the compressor needs to be equipped with delayed start protection. The interval between two starts should not be less than 3 minutes to prevent winding impact damage caused by frequent motor starts.
Domestic compression condensing units can be used as an alternative to imported models, with a compatibility rate of up to 95% with the external interfaces of cooling capacity models, making it convenient for refrigeration maintenance companies to directly replace old units.
When two equipment factories are equipped with this type of unit, the defrosting power of the air cooler is configured based on an evaporation area of 0.4 kW/㎡, and the defrosting time is set to 8-12 minutes, taking into account both defrosting effect and stable storage temperature.
For the procurement of prefabricated vegetable cold storage units for foreign trade, in addition to CE certification, some Southeast Asian engineering chambers of commerce require vibration test reports. The unit's full load vibration value should be controlled within the qualified range of 2.2mm/s.
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FAQ
What is the standard storage temperature setting for prefabricated food cold storage? The mainstream control is -18 ℃, and the temperature deviation is controlled within ± 1 ℃.
2. What is the reserved cooling capacity for the selection of prefabricated food cold storage? For frequent door opening scenarios, it is recommended to increase the cooling capacity by 20%.
How thick is the frost layer that will significantly affect the heat transfer of the evaporator? When the frost layer exceeds 3mm, the heat transfer efficiency decreases by about 38%.
How long is the minimum interval between two starts of the compressor set? Delay protection shall not be less than 3 minutes to protect the motor.
5. Should we prioritize a split machine or a condensing unit for prefabricated food cold storage? The on-site construction volume of the compression condensing unit is less.
What are the advantages of R404A compared to R507 at -18 ℃? The heat exchange stability is about 6% higher.
What is the qualified threshold for vibration of export pre packaged vegetable units? Control the full load vibration value within 2.2mm/s.
