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Why Should I Turn on Transport Refrigeration Unit for Pre-Cooling?
Sep 29, 2021
Before you load perishable cargoes, please turn on your transport refrigeration unit first for pre-cooling, which will make the cargoes more safe and fresh.

Function and importance of cargo pre-cooling:

The purpose of cold chain is to keep the quality and freshness of perishable products when they are delivered to consumers. If the whole process of the cold chain can be operated properly, the product value realized in the process of providing "newly harvested" quality products for remote end consumers is huge. In this issue, we will introduce you to the role and importance of cargo pre-cooling.

  1. Cargo Pre-cooling

After the harvest of fruits and vegetables and other agricultural products, the nutritional content, color, taste and texture will begin to decline, and these qualities are usually valued by people to measure the quality of products. Therefore, it is necessary to protect it from adverse environmental conditions such as solar radiation after harvest, and start pre-cooling and cooling treatment after harvest to remove field heat and reduce respiration, so as to maintain product quality and prolong storage period.

The main function of cold storage and refrigerated transportation equipment is to maintain or slowly reduce the temperature of products. If the perishable products without cooling treatment are directly put into the cold storage or transported, on the one hand, it will increase the energy consumption of the transport refrigeration unit, because the energy efficiency and economy of the refrigeration unit are different for different applications; On the other hand, it takes a long time to cool down, which will cause irreversible damage to the quality of perishable products whose temperature needs to be reduced below the freezing point; In addition, perishable products without cooling treatment will affect other products at storage temperature. Therefore, perishable products need to be quickly reduced to the required temperature, that is, pre-cooling, before entering the cold storage, storage and transportation links.


2、 Transportation of goods without pre-cooling will increase the energy consumption of transport refrigeration unit

The so-called pre-cooling after harvest refers to the process of rapidly reducing the central temperature of agricultural products just harvested from the field ambient temperature to the temperature suitable for refrigerated transportation and low-temperature storage. The object of pre-cooling here mainly refers to perishable goods. In fact, it is also necessary to pre-cooling the compartment of the refrigerator truck before refrigerated transportation.

In the cold chain, there are many applications of pre-cooling of perishable products. Here, we can divide them into cooling and freezing according to the temperature reached by cooling treatment. Cooling is a cold working method to reduce the temperature of perishable products to close to its freezing point without freezing. It should be pointed out that the cooling temperature of perishable fruits and vegetables should not be lower than the limit temperature of chilling injury. Freezing is a freezing processing method that reduces the temperature of perishable products below the freezing point. The choice of cooling and freezing needs to be determined according to the refrigeration characteristics and actual needs of perishable products. Generally, the shelf life of perishable products after freezing will be longer. The meat needs to be frozen before long-term storage, and the cooling operation can be carried out after short-term storage. Because the cooled meat has not been frozen, the travel and melting process of ice crystals caused by temperature fluctuation are avoided, and the quality should be closer to fresh meat and better meet the market demand.

KingClima Transport Refrigeration Units Recommend for Perishable Cargoes Delivery: 

T-560 Truck Refrigeration Units

transport refrigeration unit, truck refrigeration unit


3、 Pre-cooling has the following functions:

① Rapidly reduce the temperature of fruits and vegetables, so as to reduce the respiratory intensity and consumption, which is conducive to maintaining the fresh quality of fruits during storage and reducing decay and deterioration;
② After pre-cooling, the fruits and vegetables will consume less cold air after entering the refrigerator truck or cold storage to prevent the rise of vehicle temperature or storage temperature;
③ The pre-cooled fruits and vegetables are more resistant to cold damage in the future cold storage, which can reduce physiological diseases;
④ The fruits and vegetables without pre cooling are loaded in the refrigerator truck or cold storage. Due to the large difference between the temperature of fruits and vegetables and the temperature in the warehouse or compartment, the water evaporation of fruits is fast, which accelerates the water loss of fruits. At the same time, the humidity in the cold storage or compartment is too high, and the water vapor at the top condenses into water droplets and drops back to the fruit box, which is extremely unfavorable to storage or transportation. This problem can be avoided after pre-cooling.

KingClima Transport Refrigeration Units Recommend for Perishable Cargoes Delivery: 

T-660 Truck Refrigeration Units

transport refrigeration unit, truck refrigeration unit


Small case - Deadly broccoli

This is a serious accident caused by improper operation. When the trailer with broccoli arrived at the distribution center, two workers took out the temperature data recorder from the goods in the trailer. They immediately lost consciousness. The workers were then taken to the local hospital. Doctors initially suspected that broccoli was contaminated with pesticides, which eventually led to poisoning of workers. Of course, the real cause of workers' unconsciousness needs to be further determined.

In subsequent tests, it was found that broccoli was not contaminated with pesticides. GPS tracking and temperature records of the truck show that broccoli has a high breathing rate due to the increase of stuffy temperature, which leads to the increase of ambient temperature. The high breathing rate resulted in the increase of carbon dioxide concentration in the container, and the reason for workers' unconsciousness was exposure to high concentration of carbon dioxide when entering the trailer.
The root cause of this phenomenon is due to improper operation process and insufficient pre-cooling of broccoli.

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