To control and reduce the operating costs of cold storage, in the operation and management of machinery and equipment, we must focus on "oil, fluorine, water, and electricity"; in warehouse management, we must strictly control the five "ice, frost, water, doors, and lights". Close; in quality management, advanced technology and technology are used to improve product quality.

Experts point out that the evaporating pressure and temperature and the condensing 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, the operating parameters are continuously adjusted and controlled to operate under economical and reasonable parameters, which can ensure the safety of machinery, equipment and stored products, give full play to equipment efficiency, and save money. Water, electricity, oil, etc.

1. Prevent the evaporation temperature from being too low

A. The increase of the temperature difference between the evaporation temperature and the warehouse temperature will make the evaporation temperature too low, which will lead to a decrease in the cooling coefficient and an increase in energy consumption. It is estimated that when other conditions remain 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 of the warehouse, which will increase the dry consumption of food and reduce the quality of food.

B. The evaporation temperature usually used in my country. The difference between the evaporation temperature and the temperature of the warehouse is generally 10 °C. The evaporation temperature of the fruit and vegetable cold storage is generally designed to be about -1010 °C, the frozen storage room is -28 °C, and the freezing room is -33 °C. The temperature difference is about 15℃, while in developed countries such as Europe, the difference between the evaporation temperature and the warehouse temperature is generally 3~5℃.

C. Reasons and solutions for low evaporation temperature

(1) The evaporator (cooler) is too small

There is a problem in the design, or the actual storage variety is different from the planned storage variety, and the heat load increases. For example, the cold storage for apple storage is used to store garlic sprouts. Since the harvest period of garlic sprouts in a production area is only a few days, it is impossible to do this. Like apples, the daily purchase volume is 5%-15% of the storage capacity, but it will be full in 3 to 5 days. Therefore, if the temperature is lowered to the appropriate storage temperature in time, it can only be achieved by reducing the evaporation temperature. The evaporation area of ​​the evaporator should be increased or the evaporator should be replaced.

(2) The cooling capacity of the compressor is too large

After the warehouse load was reduced, the energy of the compressor was not reduced in time. The compressor of the cold storage is matched according to the maximum load of the refrigeration system, and the maximum load of the fruit and vegetable cold storage occurs during the storage stage of the goods. At most other times, the load of the compressor is less than 50%. When the storage temperature drops to a suitable storage temperature, the system load is greatly reduced. If a large machine is still turned on, a large horse-drawn trolley will be formed, the temperature difference will increase, and the power consumption will increase. The number of compressors to be turned on should be reduced or the number of working cylinders should be reduced with an energy regulating device according to changes in warehouse load.

(3) The evaporator is not defrosted in time

Frosting of the evaporator coil makes the heat transfer coefficient smaller, the thermal resistance increases, the heat transfer effect is reduced, and the evaporation of the refrigerant decreases. Under the condition that the compressor energy remains unchanged, the evaporation pressure of the system will decrease, and the corresponding The evaporating temperature decreases, so 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 evaporating coil, which will also reduce the heat transfer coefficient, increase the thermal resistance, reduce the heat transfer effect, reduce the evaporation of the refrigerant, and reduce the evaporation pressure of the system. , the corresponding evaporation temperature decreases, so the oil should be drained to the system in time, and the lubricating oil in the evaporator should be brought out by hot ammonia flushing.

(5) Expansion valve opening is too small

The expansion valve opening is too small, and the liquid supply volume of the system is small. Under the condition of constant compressor energy, the evaporation pressure decreases, resulting in a decrease in the evaporation temperature. The expansion valve opening degree should be increased.

2. Prevent the condensation pressure from being too high

When the condensing pressure rises, the compression function will increase, the cooling capacity will decrease, the cooling coefficient will decrease, and the energy consumption will increase. It is estimated that when other conditions remain unchanged, the power consumption will increase by about 3% for every 1°C increase in the condensing temperature corresponding to the condensing pressure. It is generally considered that the more economical and reasonable condensing temperature is 3~5 °C higher than the outlet temperature of the cooling water. Causes and solutions for the increase in condenser pressure:

(1) The condenser is too small. Replace or add condenser.

(2) The number of condensers put into operation is small. Increase the number of operating units.

(3) Insufficient cooling water flow. Increase the number of running pumps and increase the water flow.

(4) The cooling water temperature is too high. Supplement low temperature water (tap water or well water); use frost water; ensure the cooling effect of the cooling tower, the cooling tower is installed outdoors, due to the action of the fan, there will be a lot of dust, leaves, insects, etc.