Refrigerated trucks as cold chain food and goods transport commonly used motor vehicles, with the needs of social development, the demand growth rate of 20%, is an indispensable means of transportation in our daily life, the following face of the structure and working principle of refrigerated trucks to be detailed, hope to help friends in need.
● Refrigerated car classification description: refrigerated car, also known as refrigerated thermal insulation car, it is divided into two categories of refrigerated car and thermal insulation car. Thermal insulation car refers to the car with thermal insulation compartment, suitable for short-distance thermal insulation transport. Refrigerated truck refers to a car with an insulated compartment and a refrigeration device.
1. According to the refrigeration method of the refrigeration device, it is divided into: mechanical refrigerated cars, frozen plate refrigerated cars, liquid nitrogen refrigerated cars, dry ice refrigerated cars, cold refrigerated cars, etc., of which mechanical refrigerated cars are the main models of refrigerated trucks, and the vast majority of domestic refrigerated trucks are also mechanical refrigerated trucks.
2, according to the bearing capacity of the chassis classification: micro refrigerated trucks, small refrigerated trucks, medium-sized refrigerated trucks, large refrigerated trucks.
3, according to the type of compartment classification: bread refrigerated truck, van refrigerated truck, semi-refrigerated truck.
● Composition of refrigerated truck: refrigerated truck is mainly composed of car chassis, heat insulation body, refrigeration unit, temperature recorder in the car and other components, for special requirements of vehicles, such as meat hook car, can be installed meat hook, waist, aluminum alloy guide rail, ventilation groove and other optional parts.
1, refrigerated car body: generally composed of polyurethane material, glass steel, also color steel plate, stainless steel and so on. Production techniques include: split-assembled "sandwich" plate bonding type (commonly used), split-assembled injection foam type, integral skeleton injection foam type, vacuum adsorption paste, etc.
2, refrigerated truck refrigeration unit: refrigeration unit is divided into non-independent refrigeration unit and independent refrigeration unit. Domestic units and imported units, etc. General models use external chillers, and a small number of miniature refrigerated vehicles use built-in chillers. For refrigerated trucks with low temperature requirements, a cold plate in the body can be adopted (the function is equivalent to the evaporator).
● Refrigerated truck refrigeration principle There are a variety of refrigerated truck refrigeration methods, the following five are the more common refrigeration methods:
1, water ice and salt ice refrigeration: water ice refrigeration equipment less investment, low operating costs, but ordinary water (salt) ice per unit mass of heat absorption is small, the temperature in the carriage is limited, and salt ice melting will pollute the environment, food, corrosion of the carriage and value of goods damp, so water (salt) ice refrigeration is mainly in fish and other aquatic products refrigerated transport.
2, dry ice refrigeration: simple device, low investment and operating costs, easy to use, goods will not be damp. The CO2 gas produced by the sublimation of dry ice can inhibit microbial reproduction, slow fat oxidation, and impair the respiration of fruits and vegetables. However, dry ice sublimation is easy to cause frost, and too much CO2 gas will lead to breathing difficulties and necrosis of fruits, vegetables and other refrigerated objects. Moreover, the temperature in the chamber is difficult to adjust, the cost of dry ice is high, and the consumption is large, so the practical application is less.
3, cold plate refrigeration: the device itself is heavy, large volume, occupies a certain volume of the carriage, and the cold plate is only able to work for 8~15H. Therefore, cold plate refrigeration is suitable for medium and short distance transportation of medium and light refrigerated vehicles. In recent years, with the increasing prominence of energy and environmental pollution, the application of cold plate refrigeration has developed rapidly, and it has become second only to mechanical refrigeration.
4, liquid nitrogen refrigeration: simple structure, reliable operation, no noise and pollution; Liquid nitrogen refrigeration capacity, rapid refrigeration, suitable for quick freezing. The vaporization of liquid nitrogen will not cause moisture in the chamber, and nitrogen is good for food preservation and preventing dry consumption. In addition, liquid nitrogen refrigeration temperature control is accurate (plus or minus two degrees). However, the high cost of liquid nitrogen requires frequent filling, so the promotion is limited. Similarly, other low-temperature vaporized liquid gases can also be used as refrigerants, such as liquid carbon nitride.
5. Mechanical refrigeration: mechanical refrigeration methods include steam compression, absorption, steam injection, etc. At present, vapor compression is the most widely used. Compressor refrigeration unit is mainly composed of compressor, condenser, throttle valve (or expansion valve) and evaporator.
● Refrigerated truck purchase: refrigerated truck is an important link in the low temperature cold chain logistics of the key equipment. The refrigerated truck works reliably and performs stably in the refrigerated transportation process, which is the key to ensure the safety of perishable and fresh-keeping food in the transportation process. Refrigerated truck usually has a car chassis, insulation body, refrigeration unit composed of three parts. Therefore, the choice of refrigerated truck should also start from these three parts.
(1) The choice of refrigerated truck chassis: The car chassis is relatively easy to choose. Because we can only choose to meet the environmental protection of China's car sales announcement to meet the national standard of the car chassis, no matter the size of the tonnage, domestic or imported car chassis, are the same requirements, for the car chassis, customers whether they buy or entrust the car system manufacturers to buy the same.
(2) The choice of refrigerated car body: The choice of car body is related to the specific goods to be transported. Different products have different requirements for the body. For example, refrigerated trucks transporting fresh meat need customized hooks on the body; The refrigerated trucks for the distribution of stores have small batches, many varieties, and need multi-temperature refrigerated trucks; Temperature requirements are different, loading and unloading frequently, it is necessary to open more refrigerated trucks. All this, the user can be customized to the box factory according to the specific needs.
(3) The choice of refrigerated truck refrigeration unit:
(1) Choose according to the size of the refrigerated carriage: independent or non-independent units can be selected. Generally speaking, the body above 6 meters is suitable for selecting an independent unit, and the size of the independent unit can be determined according to the length of the body. The car body below 6 meters should be selected non-independent units, where the temperature can reach -20℃.
(2) According to the temperature requirements of the goods transported by the refrigerated truck: cryogenic units or fresh-keeping units can be selected. In terms of price, cryogenic fresh-keeping units are relatively cheap. For cheap fresh-keeping units, the unit itself does not have defrosting function, even if some fresh-keeping units claim to reach more than ten degrees below zero, it is an exaggeration.
(3) Choose according to the requirements of refrigerated truck distribution: For example, refrigerated trucks are used for point-by-point distribution of ice cream in cities, then it is necessary to choose a refrigerated refrigeration unit or an independent unit, and only long-distance or point-by-point distribution within the city is suitable for fan refrigeration units.
(4) According to the origin and brand of the refrigerator: whether domestic or imported units, it is necessary to pay attention to the temperature sensor of the unit is enough to be installed in the return air position of the evaporator, because the temperature sensor of the unit is installed in the return air or exhaust air position in two cases, the temperature reading will be different by 5 ° C.
● Refrigerated truck maintenance and use precautions:
1. Before loading the goods, pay attention to the pre-cooling transport equipment of the goods and cold storage in order to maintain the temperature when loading the goods while transporting. Do not reduce the temperature of the cargo or freeze it in the cold storage. If the loading temperature of the cargo is very high or the cold storage temperature is very high, it is difficult to reduce it to the temperature. Therefore, it is important to pre-cool the cargo and the cold storage in advance to reduce it to the transport temperature of the matter.
2, make the cool air circulate smoothly in the cargo room to do the reverse so that the temperature in the cold storage is maintained uniform temperature, we must pay full attention to the stacking of goods. In particular, it is important not to stack goods on the roof of the car or in the air outlet or intake of the air conditioner.
3. The rapid moving of goods into and out of the cold storage door opens, and the external air flow into the storage will cause the temperature to rise. Please move the goods in and out as soon as possible. In addition, stop the operation of the refrigerating unit when handling the goods.
4, when loading vegetables and fruits, special attention should be paid to vegetables and fruits because they will produce respiratory heat, if the circulation of cold air is not good, the temperature of the central part of the carriage will rise, thus affecting the quality of the goods. In addition, upper cargo close to the outlet of cold air may cause frostbite due to cold air, so please cover the cover cloth in advance for protection.
5, please keep the cold storage clean and hygienic transportation of food must be kept clean. If salt, fat, etc. are attached to the inner wall or the seal of the door, it is not only unsanitary, but also corrodes the carriage and shorns the life of the refrigerator.
In short, we should manage refrigerated trucks like managing their own children, first of all to thoroughly understand its structure and working principle, to understand the role of each of its components, and the characteristics of the system, combined with actual needs, purchase and management of refrigerated trucks. For the management of refrigerated trucks and other mechanical equipment and household appliances, it is necessary to carry out standard daily maintenance and maintenance, and correct use, so as to ensure the service life and use effect.