How can fruit and vegetable cold storage meet energy-saving requirements

How can fruit and vegetable cold storage meet energy-saving requirements

There are many factors to consider for energy saving in cold storage, including the performance of cold storage refrigeration system, the selection of refrigerant, the selection of compressor condenser and evaporator, the scale and layout of cold storage, the type and thickness of insulation layer, To improve the refrigeration efficiency of the cold storage, all factors should be taken into consideration, such as the number of in and out of goods, the insulation performance of the outer door, etc.

Fruit and vegetable mini cold storage refers to the cold storage board, refrigeration unit, evaporator, etc., which are pre-manufactured in the factory, and then installed on the agricultural production site to become an assembled cold storage or a civil cold storage or a semi-assembled and semi-civilized cold storage, and the storage capacity is generally less than 200 cubic meters Rice is used in cold storage for preservation and storage. Classified by design temperature, Guoshu mini cold storage is a high-temperature cold storage. Mini cold storage is composed of refrigeration system, warehouse, control system, etc. The following points should be noted during cold storage installation:

　　1. The cooling capacity of the cold storage through the enclosure structure is directly proportional to the unit heat flow of the cold storage enclosure structure. Therefore, more efforts should be made to reduce the unit heat flow indicators of the cold storage enclosure structure. To reduce the unit heat flow of the envelope structure, firstly, the thermal conductivity of the insulation material should be small, and the secondly, the envelope structure layer should be thicker. However, the thickness should generally not be too thick, otherwise problems such as increased construction costs and wasted space will occur. Insulation materials should be selected within a suitable thickness range. Under normal circumstances, insulation materials are required to have low thermal conductivity, low water absorption, good low temperature resistance, and low cost. Commonly used cold storage insulation materials include rice husk, polystyrene foam, polyurethane rigid foam and so on. Rice husk is convenient to obtain materials, but has low thermal resistance, is easy to absorb moisture, and has a large amount. The construction of the library is time-consuming, and the cost conversion is actually not lower than that of polystyrene; there are many polystyrene foam manufacturers, convenient to purchase, and thermal resistance Larger, moderate price, easy to construct and install; polyurethane rigid foam has the largest thermal resistance and the best thermal insulation performance, but the price is high.

2. Moisture and vapor insulation of the cold storage enclosure structure It is also necessary to take moisture and vapor insulation measures for the cold storage enclosure structure, otherwise the insulation performance of the insulation material will deteriorate. This means that the cold storage body has good insulation performance when it is first used. However, the reason for the deterioration of the insulation effect after a period of time is that the water vapor permeates from the high temperature side to the low temperature side, so the moisture and vapor barrier should be placed on the side of the insulation layer with high temperature.

　　3. The evaporation pressure and temperature of the cold storage are corresponding to the evaporation pressure. After knowing the evaporation pressure, the evaporation temperature can be obtained by looking up the table. Under the condition that the temperature of the cold storage warehouse is constant, the temperature difference (the difference between the evaporating temperature and the warehouse temperature) is reduced, the evaporating temperature can be increased accordingly, and the refrigeration capacity of the refrigerator refrigerator will be increased, that is, the cycle efficiency will be improved. It also saves power.

4. Cold storage defrosting operation. Generally speaking, when the frost layer on the surface of the evaporator does not have significant resistance to the air, before the flow of air through the evaporator is not reduced, the effect of the frost layer is not serious, so defrost is not necessary; When the air flow is significantly reduced, defrost should be performed. The greater the humidity of the air, the greater the difference between the evaporator temperature and the cold storage temperature, the easier it is to frost on the evaporator. Combined with the preservation process, packaging and refrigeration can reduce the dry consumption of fruits and vegetables and reduce the number of evaporator defrosts. In fact, it also played a role in energy saving of cold storage.

　　5. Different fruits and vegetables have different storage temperatures, and each type of fruit and vegetable also has a temperature range suitable for its storage. In the case of not affecting the quality of fruits and vegetables, energy-saving cold storage should choose a higher storage temperature. As the temperature of the cold storage is high, the evaporating temperature of the refrigeration system will be correspondingly increased, the refrigeration capacity of the refrigerator will be increased, and the cycle efficiency will of course also be improved. Increasing the temperature of the cold storage can also reduce the number of passes through the storage body. Heat transfer outside. The utilization rate of the energy-saving cold storage warehouse is the ratio of the actual volume of fruits and vegetables to the effective volume of the warehouse.

　　The volume utilization rate of the mini cold storage is generally not less than 0.3, and of course it cannot be too high, otherwise it will be difficult to cool down. When the volume of the fruits and vegetables to be stored changes greatly, they should be divided into two or more cold storage rooms. In addition, a reasonable storage period must be selected, which is self-evident for the energy saving of cold storage.