Supply air temperature

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Supply air temperature refers to the means of transport or containers or forced ventilation through vents through the refrigeration unit into the loading chamber temperature of the air space. Supply air temperature provided by the owner, taking care to avoid frozen or refrigerated temperature damage to the goods caused by improper settings. When the unit control temperature set at minus 5 degrees above the air temperature is usually controlled, so the set temperature and the return air temperature will be about 2 degrees temperature difference.

Many road transport refrigeration unit without supply air temperature control, usually installed in the return air at a single thermal sensor as a temperature controller. Into loading cargo at air temperature may be below the freezing point, causing cargo damage. * Return air temperature

Return air temperature is the temperature of the device has not been switched transport refrigeration or inside the air temperature inside. Return air temperature is usually considered to be within the means of transport or the average temperature inside the container cargo. * Space temperature

Space temperature is within the road transport of goods and means of transport, the average temperature. In container shipping, the U.S. Department of Agriculture quarantine rules require preservation during transport when plants sterile (refrigerated), at the loading position with four probes to record the temperature during transport.

Preservation of the goods on behalf of the average temperature of the point is difficult to determine. Even the best designed living plant itself still greater than the return air temperature is the temperature. * Temperature Range

Temperature range is determined by the load, the temperature limits decision. Provide transportation if the temperature range, the temperature of certain parts of the goods will remain out of range, which may cause the owner rejected. In many cases, the temperature limit is the product freezing. Freezing fresh vegetables or fruits are absolute limits, such as the point beyond which irreversible damage. Fruit temperature limit is the temperature below which will cause cold damage, this temperature range will be higher than the freezing point.

In addition to fruits and vegetables, low temperature limit mandatory. Fruits need to quarantine and sterilization, it must not exceed the maximum temperature tests required temperature (usually 1 degree Celsius). Due to several factors, the temperature inside the vehicle and cargo required temperature range and thermal sensor probe inlet return air temperature differences, usually 2-3 degrees normal differences.

The three differences can be controlled to a minimum, the general conveyance of heat from outside through the flow restriction to enhance the flow of cooling air or a combined control of the two methods.

* Relative Humidity

The relative humidity around the load is equally important for the duration of expiration.

Dry air will cause dehydration goods, affecting the appearance of the goods, and may reduce the weight of sale.

High relative humidity very humid air will refrigerated meat mold and bacteria on the speed, the vegetables and fruits will speed up the fungal growth.

In refrigerated transport, when the refrigeration unit is turned off for whatever reason, there will be major changes in relative humidity.

Relative humidity from 85% to nearly 100%, in this state, the propagation of microorganisms will have a great year. Fresh vegetables usually requires humidity between 90% -95%, required to achieve 98% of root crops. According to the different types of fruit, fresh fruits humidity should be maintained at 85% -95%.

Goods depends on the relative humidity of the ambient air cargo surface water activity, fresh air ventilation rate, relative humidity, and fresh air cooling unit coil temperature difference between the dew point and loading site.

By spraying or control access to the inside of fresh air ventilation to control humidity inside

* Weight Loss

The result ventilation transmission of water vapor around the load, and the unit condense on the evaporator coil, the defrosting process is discharged through the box, the weight of the goods is reduced. If air is very dry, the transmission rate will be increased, causing weight loss is also large. When unpackaged goods loaded in a hot state refrigerated transport, because of evaporation in the cooling will lose weight. In this case the refrigeration unit will also be running at full capacity, especially in the return air temperature control with the case. Evaporator coil than the dew point of the air through which the lower, so that the condensed water vapor, dry air will cause the meat and other goods on the evaporation of water. Eg beef from Celsius 20. C is cooled to 6. C will lose 2% by weight.

When the temperature is higher than transport temperature packing, you need to fight the cold in transit, for the fruits and vegetables of the same. Weight loss can be reduced through effective packaging design, but should pay attention to the use of plastic film, the film will produce condensation inside will accelerate the deterioration of the goods, you should try to play in the film vent.

In the purchase of refrigeration equipment, you should pay attention to the speed and air cooling evaporator coil structure, must ensure that the coil temperature does not drop too low, causing air dry quickly.

* Air circulation and supply

Smooth proper air circulation and air supply is important, such as poor air supply will cause less susceptible to reduction temperature of the cargo. During transport, such as the temperature of the cargo larger gap, the same weight reduction caused by the humidity and mixing effect, reduce the quality and affect shelf life.

Such as loading cargo heat, good for refrigeration and air supply to meet the conveyance or container cargo temperature requirements are equally important. Rapid cooling and maintain the proper air temperature requires sufficient space for air circulation. Gas quality is influenced by the equipment and packaging, and mainly depends on the situation of goods piled Mary.

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