There are similarities between cold storage and industrial chiller in many aspects, but they are limited to functions or some principles, but they are different in actual application areas. This article mainly explains the reduction of operating costs of cold storage. Relevant knowledge, the specific content covers the reasonable adjustment of the operating parameters of the refrigeration system, so as to improve the efficiency of the equipment and thereby achieve the purpose of reducing operating costs.
Evaporation pressure and temperature and condensation pressure and temperature of the refrigeration system are the main parameters. It is an important basis for operation and adjustment. According to the actual conditions and system changes, it continuously adjusts and controls the operating parameters to make it operate under economic and reasonable parameters. It can ensure the safety of machinery and equipment and stored products, give full play to equipment efficiency, and save Water, electricity, oil, etc.
Prevent evaporation temperature from being too low
A. The increase in the temperature difference between the evaporation temperature and the temperature of the warehouse will cause the evaporation temperature to be too low, which will cause the cooling coefficient to decrease and the energy consumption to increase. It is estimated that under other conditions unchanged, when the evaporation temperature decreases by 1 ° C, it will consume 1 ~ 2% more power. In addition, the increase in temperature difference will also increase the dehumidification capacity of the air cooler and reduce the humidity in the warehouse, which will cause the dry food consumption to increase and the food quality to decline.
B. Evaporation temperature commonly used in China. The difference between the evaporation temperature and the temperature of the warehouse is generally 10 ° C. The evaporation temperature of fruit and vegetable cold storage is generally designed to be about -1010 ° C, the frozen refrigerated room is -28 ° C, and the frozen room is -33 ° C. In actual operation, many fruit and vegetable storages The temperature difference is around 15 ℃, and the difference between evaporation temperature and warehouse temperature is generally 3 ~ 5 ℃ in developed countries such as Europe.
C. Reasons and solutions for the low evaporation temperature
(1) The evaporator (cooler) is too small: there is a problem in the design, or the actual storage type is different from the planned storage type, and the heat load is increased. For example, a cold store intended to store apples is used to store garlic tincture. The harvest time of garlic tincture is only a few days. It is impossible to achieve a daily purchase volume like apples according to 5% -15% of the storage capacity, but it must be filled in 3 ~ 5 days. Therefore, if the temperature is timely reduced to an appropriate level, Storage temperature can only be achieved by reducing the evaporation temperature.
The evaporator evaporation area should be increased or replaced.
(2) Compressor cooling capacity is too large: after the load of the warehouse is reduced, the energy of the compressor is not reduced in time. The compressor of the cold storage is matched according to the maximum load of the refrigeration system, while the maximum load of the fruit and vegetable cold storage occurs during the cargo storage phase. Most other times, the load of the compressor is less than 50%. When the temperature at the end of storage drops to a suitable storage temperature, the system load is greatly reduced. If larger machines are still turned on, a large horse-drawn cart is formed, the temperature difference increases, and the power consumption increases.
The number of compressors to be turned on should be reduced or the number of working cylinders should be reduced according to the load change of the warehouse.
(3) The evaporator does not defrost in time: the frosting of the evaporator coil reduces the heat transfer coefficient, increases the thermal resistance, reduces the heat transfer effect, and reduces the amount of refrigerant evaporation. When the compressor energy is unchanged, it will As a result, the evaporation pressure of the system is reduced, and the corresponding evaporation temperature is reduced, so it is necessary to defrost in time.
(4) There is lubricating oil in the evaporator: The lubricating oil in the evaporator will form an oil film on the tube wall of the evaporation coil, which will also reduce the heat transfer coefficient, increase the thermal resistance, reduce the heat transfer effect, and refrigerant. The decrease in evaporation leads to a decrease in the evaporation pressure of the system and a corresponding decrease in the evaporation temperature. Therefore, the system should be drained of oil in time, and the lubricating oil in the evaporator should be taken out by using hot ammonia to defrost.
(5) The expansion valve is opened too small: The expansion valve is opened too small, and the system supplies a small amount of liquid. Under the condition that the energy of the compressor is unchanged, the evaporation pressure is reduced, resulting in a decrease in evaporation temperature. Expansion valve opening should be increased.
Following some of the methods and principles listed above will definitely have a more obvious effect in reducing the operating costs of cold storage, so it is worthy of everyone's reference!
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