The cold storage for vegetables & fruits refers to the cold storage which is made up of cold storage plates, refrigeration units, evaporators, etc. which are pre manufactured in the factory and installed in the production site of agricultural products, and becomes the assembly cold storage or civil cold storage or semi assembly and semi civil cold storage, and the storage capacity is generally less than 200 cubic meters for fresh-keeping storage. According to the design temperature classification, cold storage for vegetables & fruits belongs to high temperature cold storage. The micro refrigerator is composed of refrigeration system, storehouse and control system.
Factors affecting energy consumption of fcold storage for vegetables & fruits and measures for energy saving of cold storage.
1. Cold storage enclosure
The running cooling capacity of the cold storage through the enclosure is directly proportional to the unit heat flow of the enclosure. Therefore, more efforts should be made to reduce the unit heat flow index of the cold storage enclosure. In order to reduce the unit heat flow of the enclosure, the thermal conductivity of the insulation material should be small, and the thickness of the enclosure layer should be thick. However, the thickness should not be too thick, otherwise there will be increased construction costs and waste of space and other issues. Therefore, it is necessary to select thermal insulation materials within the appropriate thickness range. Generally, the thermal insulation materials are required to have small thermal conductivity, low water absorption, good low temperature resistance and high cost.
2. Moisture proof and steam insulation of the cold storage enclosure
It is also necessary to take moisture-proof and steam insulation measures for the enclosure structure of the cold storage, otherwise the insulation performance of the insulation materials will be poor. This is the reason why the thermal insulation performance of the cold storage is good at the beginning of use, but the thermal insulation effect becomes worse after a period of time. As the water vapor penetrates from the high temperature side to the low temperature side, the moisture-proof steam barrier shall be set on the side with high temperature of the insulation layer.
3. Evaporation pressure and temperature of cold storage
The evaporation temperature corresponds to the evaporation pressure. When the evaporation pressure is known, the evaporation temperature can be obtained by looking up the table. If the temperature difference (the difference between the evaporation temperature and the warehouse temperature) is reduced, the evaporation temperature can be increased correspondingly, and the refrigerating capacity of the refrigerator in the cold storage will be increased, that is to say, the cycle efficiency will be improved, and the electric energy will be saved correspondingly.
4. Defrosting operation of cold storage
Generally speaking, when the resistance of the frost layer on the surface of the evaporator to the air is not significant, and before the air flow through the evaporator has not been reduced, the influence of the frost layer is not serious, so it is not necessary to defrost; when the air flow is significantly reduced, defrost should be carried out. The higher the air humidity, the greater the temperature difference between the evaporator and the cold storage, the easier it is to frost on the evaporator. Combined with the fresh-keeping technology, packaging refrigeration can reduce the dry consumption of fruits and vegetables, reduce the defrosting times of the evaporator, and actually play the role of energy saving in the cold storage.
5. Storage temperature and utilization rate of cold storage
The storage temperature of different fruits and vegetables is different, and each kind of fruits and vegetables has a suitable storage temperature range. Under the condition of not affecting the quality of fruits and vegetables, higher storage temperature should be selected for energy-saving cold storage. It should be noted that the temperature of the cold storage is high, and the evaporation temperature of the refrigeration system is also increased accordingly. The refrigeration capacity of the refrigerator will be improved, and the cycle efficiency will certainly be improved. It is more important to improve the temperature of cold storage to reduce the heat transfer through the storage. The utilization rate of energy-saving cold storage is the ratio of the actual volume of fruits and vegetables to the effective volume of the warehouse. The volume utilization rate of mini cold storage is generally not less than 0.3, of course, it should not be too high, otherwise, it will be difficult to cool down. When the volume of fruits and vegetables to be stored changes greatly, they should be divided into two or more refrigerated rooms.