The use of refrigerated trucks is becoming more and more widespread. Food, medicine, chemical products, electronic products, flowers, high-end clothing, high-end furniture, etc. have all been associated with refrigeration. Its purpose is to ensure stable product quality. However, product damage and other phenomena still exist during use. The reason for the correction is mainly due to the incorrect use of the refrigerated truck. So how should we use the refrigerated truck? How to avoid the risks caused by improper use? Let me introduce it to you.
1. Correct operation can ensure that the goods can be preserved and delivered in good condition.
Only by using and operating the refrigerated truck correctly can the goods be delivered and preserved in good condition. Because refrigerated vehicles are specially used for temperature-sensitive products, the guarantee of temperature is the key to refrigerated vehicles. Improper use or handling will result in the goods not being kept or shipped in perfect condition.
2. Preventive maintenance can minimize maintenance and operating costs.
In our normal use process, the maintenance and maintenance of vehicles and refrigerators are inseparable. Only when the equipment is properly maintained and maintained on time can the normal use of the equipment be guaranteed and the service life of the equipment can be extended. Usually the chassis engine is maintained and maintained according to the mileage, while the refrigeration unit is maintained and maintained according to the engine working hours. The usual refrigeration unit needs to be maintained and maintained every 500-700 hours, and the oil filter, fuel filter, and air filter need to be replaced; and pay attention to check the tightness of the belt and whether there is any leakage in the refrigeration system;
However, some brands of refrigerating units (such as American Thermo King) currently use synthetic or semi-synthetic engine oil instead of ordinary engine oil in order to meet the needs of environmental protection, minimize damage to the environment, and reduce the discharge of harmful substances, thereby prolonging the life of the engine. Maintenance time, usually according to 2000 hours to do a maintenance. The discharge of used oil is thus reduced. In addition, scientific experiments have proved that by using this high-end engine oil, not only the wear and tear on the engine can be reduced, but also the fuel consumption of the engine can be reduced. Therefore, scientific maintenance and maintenance can not only ensure the integrity of the equipment, but also reduce operating costs.
3. Proper packaging is essential to protect the goods.
For frozen goods, use non-ventilated packaging boxes, and for fresh goods, use sidewall-ventilated packaging boxes. The packing box must be compressive. Because the frozen cargo is not allowed to have wind blowing over the surface of the frozen cargo, because the wind blows over the surface of the frozen cargo, the moisture in the cargo will be lost, resulting in a decrease in the quality of the cargo. This year, our country formulated that all quick-frozen foods in bulk are not allowed to be sold, and this is the reason why they must be sold in packaging. Due to its own characteristics, fresh goods are still in a breathing state during storage and transportation. If they are not well ventilated, the goods will deteriorate and be damaged. Therefore, it is necessary to ensure that such goods have good ventilation and ventilation.
4. Set the thermostat at the desired temperature, pre-cool the car for 1.5 hours to remove the heat trapped in the car; turn off the refrigeration unit when loading, and quickly load the car.
When loading, the compartment must be pre-cooled or pre-heated. Because the vehicle is parked in the open air, the temperature in the cabin is usually the temperature of the outside environment. If the temperature of the goods being transported is not the ambient temperature, and the goods are loaded into the compartment, the ambient temperature will affect the temperature of the transported goods, resulting in a change in the quality of the transported goods. Therefore, the compartment must be pre-cooled to the required temperature before loading. However, during loading (as with unloading) the refrigeration unit must be switched off. Many people do not turn off the refrigeration unit when loading and unloading goods. In fact, this is a very wrong operation.
The reason is: when we pre-cool the compartment, if we do not turn off the machine and open the compartment door, since the fan of the evaporator of the refrigeration unit is working, the front side of the fan is positive pressure, while the back side is negative pressure, so the cold air flows from the upper part of the compartment. blow out, and the lower part will quickly suck in the hot air from the outside, which will cause the temperature in the compartment to rise rapidly; The speed of air passing into the compartment is relatively slowed down.
5. The goods must be pre-cooled to the required temperature, and the temperature of the goods must be checked when loading; the refrigeration unit is used to maintain the temperature of the goods, not to reduce the temperature of the goods.
Many refrigerated truck users have a wrong concept, always thinking that the refrigerating unit on the refrigerated truck can freeze or heat the goods loaded in the compartment to the required temperature at will. Therefore, load the goods that are lower than the temperature required for transportation into the compartment, and then set the refrigeration unit to the required transportation temperature, and reduce or increase the temperature of the goods to the required temperature after a certain period of time.
However, the fact is the opposite. Not only can the temperature of the goods not drop (or rise), but the goods will be damaged or deteriorated. Because the refrigeration unit of the refrigerated truck does not reduce the temperature of the goods, but maintains the temperature of the goods. It is like the quilt we used to sell cold drinks in the past to wrap the goods. When the external cold (heat) source flows into the compartment through radiation, conduction, and convection, it is taken away by the cold air blown out by the refrigeration unit, and the heat source is isolated from entering the cargo.
Therefore, when loading, the temperature of the loaded goods must be measured first. If the set point temperature of the refrigeration unit is higher or lower than the temperature of the cargo, it will be difficult for the temperature of the cargo in the compartment to reach the temperature required for transportation. The storage temperature of the goods must be consistent with the transportation temperature. If the temperature of the goods changes frequently, moisture will be lost, which will lead to quality changes of the goods, which will shorten the shelf life of the goods.
6. Even if the capacity of the unit exceeds what is actually needed, insufficient air circulation will be the main cause of spoilage; any blockage around the cargo may cause - "hot spots".
A qualified refrigerated truck must ensure good ventilation on the six sides of the compartment and no blockage on the six sides of the goods; good air circulation can ensure that the goods are transported under appropriate temperature requirements. The cold (hot) gas blown out by the refrigerating unit isolates the cold (heat) source entering the compartment from the cargo, thereby protecting the cargo. If a blockage occurs at a certain location, the cold (hot) source in that part will directly enter the item, resulting in a change in the temperature of the cargo. Make sure the return air shutters are in good condition; do not block the inlet to the evaporator (return air); insufficient return air will create irregular circulation of cold air and cause the top cargo to freeze.
7. The goods must be stacked on double-sided pallets; plastic film cannot be wrapped on fresh-keeping pallets, as the film will block the circulation of cold air to the goods; the floor under the goods must not be blocked.
Generally, the floors of refrigerated trucks use ventilated aluminum rail floors; however, there are also some refrigerated trucks that do not have aluminum rails and use flat non-slip floors. Usually used as a third-party transport company or an enterprise transport vehicle for dairy products, a flat non-slip floor is used for the purpose of being suitable for the transportation of various products, or for easy cleaning of the ground. However, care must be taken when loading, and double-sided pallets must be used for loading to ensure the circulation of cold air on the ground. It is strictly forbidden to stack goods directly on the flat floor.
8. Do not stack goods in front of the evaporator outlet, otherwise it will block the cold air flow; blockage above the goods will cause a short circuit of the cold air flow. Maintain a minimum distance of 225 mm between the top of the cargo and the roof of the vehicle.
When loading, do not stack the goods too high, and make sure that the loading height is not higher than the plane height of the air outlet. If the front of the air outlet is blocked by the goods or is too close to the goods, it will not only affect the storage and transportation temperature of the goods, but also affect the normal operation of the refrigeration unit. Because the air outlet is blocked by the goods, the cold air (or hot air) cannot circulate normally in the compartment, thus causing the local temperature of the goods to rise. On the other hand, due to the defrosting design of the refrigeration unit, some air induction defrosting is used.
When the goods are too close to the air outlet, the coil in the evaporator of the unit will quickly frost (or ice), and the air sensor switch will act immediately, and the unit will quickly enter the defrosting state; when the coil temperature rises to 9 degrees (design temperature) or so, the defrost ends immediately. As a result, the above-mentioned operations will be repeated in the unit, resulting in the phenomenon that the temperature in the compartment cannot be lowered. The only impression for everyone is that the unit always defrosts frequently. In fact, it is due to the fact that the goods are loaded too high (too much).
9. The interior of the carriage must be kept clean; there should be no wrapping paper and paper scraps left on the ground; the debris will block the air flow or be sucked by the evaporator.
When using a refrigerated truck, the floor of the car should be kept clean. Due to the action of the evaporator fan, the air will circulate in the cabin, causing debris or dirt on the ground to be sucked by the evaporator fan. Long-term action will cause a large amount of impurities to be sucked into the evaporator coil, thus affecting the cooling effect of the refrigeration unit. Because the coil will be surrounded by impurities a little bit, resulting in a decrease in the heat exchange rate of the coil. Therefore, after using the refrigerated truck for several years, everyone will feel that the cooling effect is not as good as it was at the beginning. Apart from the cause of its own failure, it is because the coil is too dirty. Therefore, ensuring the cleanliness of the ground in the compartment is the key to ensuring the normal operation of the refrigeration unit.
10. Proper handling; the refrigerator should be turned off when the door is opened; the time for opening the door should be shortened as much as possible; strip curtains should be used as much as possible when loading and unloading goods. Use dividers to separate dry goods (empty crates) from perishable items.
In order to ensure the temperature of the goods in the compartment, it is recommended to use strip curtains for urban delivery vehicles to ensure that the cold air in the compartment will not be quickly lost when the cargo is unloaded quickly (when the refrigeration unit is not turned off). Goods with different temperatures are strictly prohibited to be stored in the same compartment space. It should be placed separately with partitions. Since the freezer is used to maintain the temperature of the goods, not to cool them down, mixing goods with different temperatures will affect the temperature of the goods and affect the quality of the goods. Correct operation and use of refrigerated trucks is the key to ensuring the quality of temperature-controlled goods. It is also the place to ensure that the refrigeration equipment can work normally.