How to Make Refrigeration Systems More Energy - Efficient?

The energy consumption of cold storage operation generally accounts for over 70% of the total energy consumption of cold chain logistics. Therefore, energy conservation in cold storage is of particular importance for cold chain logistics.

Under normal circumstances, in the actual operation of the refrigeration system, since the temperature conditions are constantly changing, only through the careful operation of cold storage management personnel and the accurate adjustment of the operation of cold storage refrigeration equipment can the refrigeration system always be in the most ideal working state and achieve the effect of high efficiency and energy conservation.

When there is an oil film 0.1mm thick inside the evaporator coil, in order to maintain the set temperature requirement, the evaporation temperature will drop by 2.5°C, and the power consumption will increase by more than 10%.

When the scale on the water pipe wall in the condenser reaches 1.5mm, the condensation temperature will rise by 2.8°C compared with the original temperature, and the power consumption will increase by 9.7%. When there is non - condensable gas mixed in the refrigeration system and its partial pressure value reaches 0.196MPa, the power consumption will increase by about 18%. It can be seen from this the importance of regularly discharging oil, removing scale and releasing air in the cold storage system.

The power consumption of the cold storage room is calculated according to the amount of cooling consumption of the cold storage room, usually including two parts: one is the cooling consumption when the goods are cooled and refrigerated; the other is the cooling consumption of the cold storage room itself and its operation and management. The key to saving electricity lies in the utilization rate of the cold storage room. A cold storage room with a low utilization rate consumes more cooling and thus more electricity. In actual operation, since the power of the equipped motor is selected according to the refrigeration capacity of the unit, that is, the cooling consumption of the warehouse is less than the refrigeration capacity of the refrigerator. During the off - season operation of the cold storage, due to the small number of goods stored in the cold storage room, the operation is like using a big horse to pull a small cart, wasting electric energy. Therefore, during the off - season, the goods in several cold storage rooms can be merged into one according to the storage temperature in a timely manner to reduce energy consumption.

Cold storage lighting should be considered comprehensively from the perspectives of energy conservation and environmental protection based on safety, science and rationality, taking into account factors such as the area, height and temperature of the cold storage room. The lighting in the cold storage is generally concentrated in the working area. Under the condition of ensuring the safety of operators, the lights should be turned off in a timely manner to reduce the heat load and power consumption of the warehouse.

At the same time, high - efficiency, low - consumption and pressure - resistant lighting fixtures should be used as much as possible to reduce the replacement frequency of the fixtures. The LED lighting system has the advantages of environmental protection, power saving, uniform illumination, good luminous efficiency at low temperatures and high power supply efficiency. It is a promising new light source and also the future development direction of the lighting system in cold storage.

Generally speaking, for every 1°C increase in the evaporation temperature of the cold storage, 2 - 2.5% of energy can be saved. Therefore, on the premise of meeting the product refrigeration process, the evaporation temperature can be increased as much as possible by adjusting the liquid supply. The thermal resistance of the frost layer is generally much larger than that of the steel pipe.

When the thickness of the frost layer is greater than 10mm, its heat transfer efficiency drops by more than 30%. When the temperature difference between the inner and outer walls of the pipe is 10°C and the warehouse temperature is at - 18°C, after the refrigeration system of the pipe - type evaporator has been running for one month, its heat transfer coefficient K value is only about 70% of the original. When the frosting of the air - cooler is particularly serious, not only the thermal resistance increases, but also the air flow resistance increases. In severe cases, air supply will be impossible. Therefore, the surface of the evaporator should be defrosted in a timely manner. In the refrigeration systems of large and medium - sized cold storages, hot ammonia (fluorine) defrosting and water defrosting are generally used instead of the high - energy - consuming electric defrosting method. For small - scale Freon refrigeration systems, in order to simplify the pipeline, the electric defrosting method can be adopted, but the appropriate electric power should be configured according to the heat required for the frost layer to melt.

For example, when the compression ratio is less than 8 after the goods are delivered to the low - temperature freezing warehouse or quick - freezing device, many low - temperature cold storages start to use two - stage compressors as soon as they start up, increasing the energy consumption of the cold storage. The correct method is to first use single - stage refrigeration compression.

When the evaporation pressure drops and the compression ratio is greater than 8, then switch to the two - stage compression refrigeration method.