The emergence of refrigerated trucks in Chongqing has greatly improved people's living standards and quality. With refrigerated trucks, we can eat around the world without leaving home.

So, how do refrigerated trucks refrigerate and what are the refrigeration methods? The refrigerated truck manufacturer briefly explained to us that the refrigeration of water ice and salt ice in refrigerated containers is at atmospheric pressure, and the melting point of ice is 0 ° C. The heat absorption value when ice melts is 334.8 kJ/kg. Adding salt to water ice can lower its melting point.

Within a certain range, the higher the salt content in water ice, the lower its melting point. Experiments have shown that when the amount of salt added is 29% of the mass of water ice, the melting point of the mixture can reach a lower value of -21.2 ° C. If the salt content increases, the melting point will no longer decrease. Usually, different salt ice components are selected based on the appropriate temperature of the refrigerated goods being transported.

For example, using salt ice with a salt content of 22%, the cabin temperature can be maintained at -18 to -13 ° C. Water ice refrigeration equipment requires less investment and has lower operating costs, but ordinary water ice has a smaller heat absorption per unit mass and limited cooling capacity in the cabin.

In addition, the melting of salt ice can also pollute the environment, food, corrosive carriages, and valuable goods. Therefore, water (salt) ice refrigeration should first be used for the refrigerated transportation of fish and other aquatic products.

Dry ice refrigeration operates at atmospheric pressure, with low temperature increase and high heat absorption. Therefore, as a cooling source for the engine compartment, dry ice can not only achieve lower temperatures but also greater cooling capacity.

Therefore, refrigeration methods are suitable for the transportation of frozen food. Dry ice refrigeration equipment is simple, with low investment and operating costs, easy to use, and the goods will not get wet. Dry ice can increase the production of CO gas, inhibit microbial growth, slow down fat oxidation, and weaken the respiration of fruits and vegetables.

However, the increase of dry ice can easily cause frosting. Excessive carbon dioxide gas will cause refrigerated fruits and vegetables to be difficult to breathe and die, the temperature inside the carriage to be difficult to regulate, dry ice is expensive and consumes a lot, making it less practical.

The principle of cold plate refrigeration is to use the cooling capacity stored in the refrigerant for cooling. Before transportation, the cold plates in the cold storage should be filled with cool air to cool and freeze them. Then, during transportation, the cold medium in the cold plates should be used to melt and absorb heat, so that the temperature reaches the appropriate temperature range for the transported goods in the compartment. Inside. Therefore, this cold plate is also known as a cold storage plate.