Most commercial refrigeration equipment consists of a compressor and a condenser, outside the cold box, and an evaporator inside. The refrigerant travels in a circuit into and out of the area to be cooled, usually within an insulated compartment. This compartment can range in size from a typical refrigerator interior to a walk-in cubicle in a restaurant to a whole air-conditioned building.
Refrigeration
The refrigerant is compressed outside the area to be refrigerated. It is squeezed in the process to occupy a smaller volume. The temperature is suddenly made higher because it contains the same amount of caloric heat in a smaller volume. Still, under tremendous pressure and occupying a smaller volume, the refrigerant travels via the pipe to the inside area to be cooled. It is forced through a diffuser, which consists of a pin-sized aperture, causing the pressure to drop instantly.
Now the refrigerant expands to occupy a greater volume, and as a consequence, its temperature drops, so it becomes much colder. The refrigerant typically passes through finned piping resembling an automotive radiator. The coldness transfers to the interior of the box, whereupon the new warmer and less pressurized refrigerant journeys back to the compressor begin another cycle.
Cold storage refrigeration introduction
China’s food refrigeration uses a vapour compression refrigeration system. In a broad sense, this refrigeration system should include a refrigeration cycle system, cooling water system, lubricating oil system, indirect cooling, and refrigerant circulation system.
The joint action of these parts achieves the refrigeration effect. The refrigeration cycle system is the most important in these parts. The so-called refrigeration system is often the refrigerant circulation system.
According to the type of refrigerant, the refrigerant circulation system can be classified into an ammonia refrigeration system and a fluorine refrigeration system.
The refrigeration principle of the refrigerator is that the compressor compresses the working medium from low-temperature and low-pressure gas into high-temperature and high-pressure gas and then condenses into a medium-temperature and high-pressure liquid through the condenser. After the throttling valve is throttled, it becomes a low-temperature and low-pressure liquid so that the refrigerant restores the ability to evaporate heat. The low-temperature low-pressure liquid working medium is sent to the evaporator, absorbing heat in the evaporator and evaporating into low-temperature and low-pressure steam. It is again sent to the compressor to complete the refrigeration cycle.
The heat exchange equipment used in the cooling room, freezing room, refrigerating room, cold storage room, ice-making room and ice storage is cooler, waste heat exchanger, shell-and-tube water heat exchanger, evaporator, condenser and so on.
The temperature in the cooling compartment is generally maintained at 0-2 °C.
According to temperature, assembled cold storage can be divided into:
1) L-level preservation library. Mainly used for storing fruits and vegetables, eggs, medicinal materials, fresh-keeping and drying, the food temperature into the warehouse is +30 °C; the cold storage temperature is generally +5 ~ -5 °C.
2) Class D refrigerator. It is mainly used for storing meat, aquatic products and products suitable for this temperature range; the temperature of the food in the warehouse is +15 °C, and the cold storage temperature is generally -5 to -20 °C.
3) Class J low-temperature library. Mainly used for storing ice cream, low-temperature food and medical supplies, the temperature of the food into the warehouse is +15 °C, and the temperature of the cold storage is generally -25 °C.
For ammonia cooling and fluorine cooling, the plate can be selected from SS316.