The refrigeration principle of refrigerated trucks

Refrigeration Principle of Refrigerated Trucks

Refrigerated trucks are an essential tool in the fresh transportation industry. Let's learn about the refrigeration principle of refrigerated trucks together.

I. Refrigeration Methods for Refrigerated Trucks

1. Dry ice refrigeration

The device is simple, with low investment and operating costs, convenient to use, and goods are not damp. The CO2 gas produced by dry ice sublimation can inhibit the reproduction of microorganisms, slow down fat oxidation, and weaken the respiration of fruits and vegetables. However, dry ice sublimation is prone to cause frost, and excessive CO2 will cause cold-stored goods such as fruits and vegetables to have difficulty breathing and die. Moreover, the temperature inside the compartment is difficult to adjust, and the cost of dry ice is relatively high, and the consumption is large, so it is rarely used in practice.

2. Water ice and salt ice refrigeration

Water ice refrigeration has a low investment in equipment and low operating costs, but the specific heat capacity of ordinary water (salt) ice is small, and the cooling in the compartment is limited. After salt ice melts, it will pollute the environment and food and corrode the compartment.

3. Mechanical refrigeration

The mechanical refrigeration methods of refrigerated trucks include vapor compression, absorption, and vapor injection, among which vapor compression is currently the most widely used. The compressor, condenser, throttle valve (or expansion valve), and evaporator mainly constitute the refrigeration unit of the compression refrigeration system.

4. Liquid nitrogen refrigeration

The device has a simple structure, reliable operation, no noise or pollution, a large amount of liquid nitrogen refrigeration, and rapid cooling, which is suitable for quick-freezing. The gasification of liquid nitrogen will not cause dampness in the compartment, and nitrogen has the advantages of preserving food and preventing drying. In addition, the temperature control of liquid nitrogen refrigeration is precise (positive and negative two degrees). However, the cost of liquid nitrogen is high, and it needs to be refilled frequently, so its promotion is limited.

5. Cold plate refrigeration

The device itself is relatively heavy and bulky, occupying a certain volume of the compartment, and the cold plate can only work for 8-15 hours after being chilled once. Therefore, cold plate refrigeration is suitable for medium and light-duty refrigerated trucks for medium and short-distance transportation. In recent years, with the increasingly prominent problems of energy and environmental pollution, the application of cold plate refrigeration has developed rapidly and has become the second most common refrigeration method after mechanical refrigeration.

II. Maintenance Notes for Refrigerated Trucks

  1. Pre-cool the goods and the refrigeration unit before loading

Transportation equipment is designed to maintain the temperature of the goods during loading and transportation, and cannot lower the temperature of the goods or freeze them in the refrigeration unit. If the goods are loaded when the temperature is high, or the refrigeration unit is not at the appropriate temperature, it will be difficult to bring them down to the proper temperature. Therefore, it is necessary to pre-cool the goods and the refrigeration unit beforehand.

2. Ensure proper circulation of cold air among the goods

To maintain a uniform temperature throughout the refrigeration unit, it is important to pay attention to the placement of the goods. In particular, do not stack goods up to the roof or in front of the air vents.

3. Quickly load and unload the goods

Opening the refrigeration unit door will allow outside air to enter, causing the temperature inside to rise. Therefore, it is important to quickly load and unload the goods. In addition, when loading and unloading, it is necessary to stop the refrigeration unit from running.

4. Special attention should be paid when loading vegetables and fruits

Vegetables and fruits produce heat during respiration. If the circulation of cold air is not good, the temperature in the central part of the refrigerated truck will rise, affecting the quality of the goods. In addition, goods located closer to the air vents may experience frostbite due to the cold air. Therefore, it is necessary to protect them with covers or cloths.

5. Keep the refrigeration unit clean and hygienic

When transporting food, it is important to keep the refrigeration unit clean. If salt, fat, or other substances adhere to the inner wall or door seal, it not only affects hygiene, but also corrodes the vehicle, shortening the life of the refrigerated truck.

The refrigeration principle of a Fridge Freezer Trailers For Sale is achieved through the tight combination of many components, and every small detail is closely related to the refrigeration effect. It is important to have a sufficient understanding of refrigerated trucks to fully appreciate their capabilities.