How to reduce the operating cost of cold storage is the most concerned topic of every cold storage manager, and the evaporating pressure and temperature and condensing pressure and temperature of the refrigeration system are the main parameters, which are the important basis for operation and adjustment. According to the actual conditions and system changes, the operating parameters should be continuously adjusted and controlled to operate under economical and reasonable parameters, so as to ensure the safety of the machinery and equipment and the stored products, give full play to the equipment efficiency, and thus achieve the purpose of reducing operating costs.

1. Prevent the evaporation temperature from being too low

1. 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 10 °C, the freezing room is -28 °C, and the freezing room is -33 °C. The temperature difference is around 15°C.

2. If the temperature difference between the evaporation temperature and the warehouse temperature increases, the evaporation temperature will be too low, which will lead to a decrease in the cooling coefficient and an increase in energy consumption. Under the condition that 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.

3. 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 variety is different from the designed storage variety, and the heat load increases. Therefore, if the temperature is to be lowered to the appropriate storage temperature in time, it can only be achieved by reducing the evaporation temperature. The solution is to increase the evaporation area of ​​the evaporator or replace the evaporator.

②The cooling capacity of the compressor 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, 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 solution is to reduce the number of compressors turned on according to the change of the warehouse load or reduce the number of working cylinders with an energy regulating device.

③The evaporator is not defrosted in time. Frost on the evaporator coil reduces the heat transfer coefficient, increases the thermal resistance, reduces the heat transfer effect, and reduces the evaporation of the refrigerant. When the compressor energy remains unchanged, it will lead to system failure. The evaporating pressure decreases, and the corresponding evaporating temperature decreases, so it is necessary to defrost in time.

④There 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, and reduce the refrigerant evaporation. , resulting in the reduction of the evaporation pressure of the system and the corresponding reduction of the evaporation temperature, 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 frosting.

⑤ The expansion valve is opened too small. The expansion valve is opened too small, and the liquid supply amount of the system is small. Under the condition of constant compressor energy, the evaporating pressure decreases, resulting in a decrease in the evaporating temperature. The expansion valve opening should be increased. 2. Prevent the condensation pressure from being too high 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, a large amount of dust, leaves, insects, etc. will enter the tower, which takes a long time. In addition, the nozzle holes of the water distributor will be blocked by debris or scale after a long time of use, which will affect the cooling effect. Therefore, the cooling tower needs to be cleaned regularly to keep it clean. When the water temperature is close to the air wet bulb temperature, the cooling tower fan should be turned off to reduce power consumption.

5. The heat exchange area of ​​the condenser is reduced. Sufficient heat exchange area is an important guarantee for the heat exchange effect of the condenser. Especially the refrigeration system using the compression condensing unit, because the condenser of this unit has the function of the liquid receiver, when the liquid level in the condenser is too high, the condensing effect of the condenser is seriously affected, and the condensing temperature and pressure increase, The power consumption of the refrigeration compressor increases. Therefore, attention should be paid to the change of the liquid level during operation, and the condensed liquid in the condenser should be discharged in time. When the refrigerant is added, the added amount should be strictly controlled to ensure sufficient heat exchange area of ​​the condenser.

6. The water distribution of the condenser is uneven. When the water distribution is uneven, the water flow in some pipes is the largest, and the water flow in some pipes is small, which will reduce the heat transfer efficiency and increase the condensation temperature. A good water flow distribution should be that the water flow rotates down the pipe wall. If the water flow flows down from the middle of the pipe, most of the water flow will not have the effect of condensation. Therefore, when the water distribution of the water distributor is uneven, the water distributor should be replaced.

7. There is scale on the condenser pipe. The scale on the condenser pipes leads to an increase in thermal resistance, a decrease in the heat transfer coefficient, a decrease in the heat exchange effect, and an increase in the condensation temperature. Improve water quality and descale in time.

8. There is air in the condenser. The air in the condenser increases the partial pressure in the system and the total pressure, and the air also forms a gas layer on the surface of the condenser, resulting in additional thermal resistance, reducing the heat transfer efficiency, resulting in an increase in the condensation pressure and condensation temperature.