Comparison of Frosting Mechanism and Defrosting Scheme for Cold Storage Evaporators | Selection of Electric Heating Defrosting, Water flushing Defrosting, and Thermal Heating Defrosting
The surface temperature of the evaporator fins is below 0 ℃, and water vapor condenses in the air. The frost layer is insulated and has a thickness of more than 3mm, resulting in a significant decrease in heat transfer efficiency and a continuous decrease in evaporation pressure.
There are three mainstream defrosting methods for cold storage: electric defrosting, water flushing defrosting, and hot air defrosting. Small fresh-keeping and low-temperature cold storage often use electric heating frost; Priority hot air defrosting for large frozen tunnels; High humidity aquatic storage can choose water flushing defrost.
The Xiteluo supporting air cooler supports three defrosting configurations. The hot air defrosting utilizes the exhaust heat of the compressor, resulting in the lowest energy consumption. However, the pipeline design is complex and requires defrosting solenoid valves and one-way valves.
Electric defrosting has simple control and low modification cost. The disadvantage is that defrosting consumes high power, and the defrosting heat will dissipate into the warehouse. After defrosting, the unit needs to consume additional power to reheat.
The defrosting cycle cannot be fixed, and a fixed defrosting time can easily result in thin and useless frost, or a thick frost layer before defrosting; Recommend using * * time+temperature dual control * *.
Many engineering companies have set the termination temperature for defrosting improperly, resulting in premature defrosting and accumulation of residual ice on the fins. After several cycles, the ice shell becomes thicker and the fan airflow decreases.
The hot air defrosting pipeline should be well insulated. During defrosting, high-temperature refrigerant flows back, and liquid return protection should be set up to prevent liquid refrigerant from returning to the compressor and causing liquid hammer in the later stage of defrosting.
The water vapor in the seafood processing cold storage is heavy, and the speed of frost layer formation is fast. The defrosting drip tray and drainage pipe must be accompanied by heat, and the drainage pipe may freeze and block, causing defrosting water to overflow and damage the storage board.
Tropical high humidity cold storage for foreign trade, with a humidity of over 90% for a long time and rapid frost formation. The solution prioritizes dual control defrosting and increases drainage and heat tracing power to avoid ice blockage in drainage.
During the defrosting period, the fan must be stopped. If the fan does not stop, hot air will be blown into the warehouse, resulting in poor defrosting effect, severe temperature fluctuations in the warehouse, and damage to the quality of food preservation.
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FAQ
How thick is the frost layer that significantly affects heat transfer? When the frost layer exceeds 3mm, there is significant heat transfer attenuation.
Which of the three types of defrosting has the lowest energy consumption? Hot air defrosting, utilizing compressor exhaust heat.
What are the advantages and disadvantages of electric heating cream? Simple and inexpensive control, high power consumption for defrosting, and large fluctuations in storage temperature.
4. Recommended defrosting control plan? Dual control of time and temperature, it is not recommended to simply schedule.
What is the biggest risk of thermal defrosting? Defrosting and returning liquid cause compressor fluid hammer.
Why do high humidity water storage drainage pipes need heat tracing? Prevent defrosting water from freezing and blocking pipes.
Should the cold air fan be running during defrosting? The fan stops during the defrosting stage.
