Dry ice refrigeration

Under one atmospheric pressure, the sublimation temperature of dry ice (solid CO2) is low (-78.9°C), and the sublimation heat absorption is large (573.5kJ/kg). at -20°C), and a larger cooling capacity can be obtained. Therefore, this refrigeration method is suitable for the transportation of frozen food.

     The dry ice refrigeration device is simple, low in investment and operating costs, easy to use, and the goods will not be affected by moisture. The COZ gas produced by the sublimation of dry ice can inhibit the reproduction of microorganisms, slow down the oxidation of fat and weaken the respiration of fruits and vegetables, which can play a very good role in keeping fresh.

Water ice and salt ice refrigeration

     At atmospheric pressure, the melting point of ice is 0°C. The heat absorption when ice melts is 334.8kJ/kg. Adding salts to water ice can lower its melting point. Within a certain range, the more salt content in water ice, the lower the melting point. Experiments have proved that when the mass of salt added is 29% of the mass of water ice, the melting point of the mixture can reach the lowest value -21.2°C. If you add more salt, the melting point will no longer drop. Usually, salt ice with different compositions is selected according to the suitable temperature for the transportation of refrigerated goods. For example, if salt ice with a salt content of 22% is used, the temperature inside the compartment can be maintained at -18~-13°C.

     The water ice refrigeration device has low investment and low operating cost, but the heat absorption per unit mass of ordinary water (salt) ice is small, and the cooling in the compartment is limited. In addition, the melting of salt and ice will pollute the environment, food, corrode the carriage and damp the goods. Therefore, water (salt) ice refrigeration is mainly used for refrigerated transportation of fish and other aquatic products.

     cold plate refrigeration

     The principle of cold plate refrigeration is to use the cold energy stored in the cold storage agent (refrigerant) to refrigerate. Before transportation, the cold storage agent in the cold plate in the compartment is "cooled" to make it cool and freeze, and then the cold storage agent in the cold plate is used to melt and absorb heat during transportation, so that the temperature in the compartment can be kept within the appropriate temperature range of the transported goods Inside. Therefore, the cold plate is also called "cold storage plate".

     The structural type of the cold plate refrigeration device is divided into integral type and split type. The integral power unit, refrigeration unit and cold storage plate are all placed on the vehicle; the split type is only equipped with a refrigeration unit and cold storage plate on the vehicle. When parking, use the ground-fixed power device to drive the refrigeration unit to "charge cold" the cold storage plate. The latter is often used in practical applications. Commonly used cooling agents are eutectic solutions with low melting points, and their melting points are usually about 10°C lower than the optimum temperature in the compartment. When the optimum temperature of the transported goods changes, the composition of the selected eutectic solution will also change accordingly.

     The cold plate device itself is heavy and bulky, and occupies a certain volume of the compartment, and the cold plate can only continue to work for 8~15 hours after one charge. Therefore, cold plate refrigeration is suitable for medium and short-distance transportation of medium and light refrigerated vehicles. In recent years, with the increasingly prominent problems of energy and environmental pollution, the application of cold plate refrigeration has developed rapidly, and it has become the second only to mechanical refrigeration. Way.

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Xiamen Hefengli Dry Ice Decontamination Equipment Co., Ltd., referred to as Hefengli Dry Ice, was established in 1999. It is a professional enterprise dedicated to the application of dry ice in China. It has formed a complete industrial chain of R&D, manufacturing, sales and after-sales. The company's brand is HORECO2, and Hefengli has a doctoral-level R&D team. Its main products include Dry ice granulator & block making machine, Dry ice cleaning machine, dry ice automatic production line, dry ice intelligent cleaning, supply of dry ice of various specifications, dry ice Cleaning service and leasing, Dry ice insulation box, dry ice equipment accessories and related intelligent products; 18 dry ice manufacturing factories have been deployed to provide a complete dry ice distribution service network and provide customers with a cost-effective experience.