The evaporating pressure, 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.
The reason of the evaporation temperature too low
1. Evaporator (cooler) is too small
There is a problem in the design, or the actual storage variety is different from the design planned storage variety, and the heat load increases.
Solution: The evaporation area of the evaporator should be increased or the evaporator should be replaced.
2. The compressor cooling capacity 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. Most of the time, 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.
Solution: reduce the number of compressors turned on or reduce the number of working cylinders with an energy regulating device according to the change of warehouse load.
3. Evaporator not defrosted in time
Solution: 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 energy of the compressor remains unchanged, the evaporation pressure of the system will decrease. The corresponding evaporation 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 frosting.
5. Expansion valve open too small
The opening of the expansion valve is too small, and the liquid supply of the system is small. Under the condition of constant compressor energy, the evaporating pressure decreases, resulting in a decrease in the evaporating temperature.
Solution: The opening degree of the expansion valve should be increased.
Causes of high condensing pressure
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 to 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 increase the condense.
2. The number of condensers put into operation is small, and the number of operation is increased.
3. If the cooling water flow is insufficient, increase the number of water pumps and increase the water flow.
4. Condenser water distribution is uneven.
5. The scale on the condenser pipeline leads to an increase in thermal resistance, and the water quality should be improved and scaled in time.
6. There is air in the condenser. The air in the condenser increases the partial pressure in the system and the total pressure. The air also forms a gas layer on the surface of the condenser, resulting in additional thermal resistance, which reduces the heat transfer efficiency, resulting in condensation pressure and condensation. When the temperature rises, air should be released in time.
Post time: Jan-10-2022