7.2.11   Future trends
Currently, there are four main trends in the development of refrigeration units which are all aimed at reducing energy consumption. This is necessary on the one hand because of the international agreements on CO2 emissions, on the other hand because increasing oil prices make it economically attractive again.
  1. Scroll compressors will replace piston compressors. In addition, scroll compressors are being developed which can be adjusted mechanically so that refrigeration performance is no longer adjusted by throttling the suction line or by means of a hot gas bypass. This will also considerably reduce energy consumption.

  2. The circulating fans in the container will in future be variable speed and will be regulated by the temperature differential between the supply air and the return air. Since fans are responsible for a significant amount of a refrigerated container's energy consumption (approximately 2 kW at high speed), and heat produced by the fans also has to be extracted from the container, the highest saving potential is to be expected here.

  3. The fresh air flaps will be automatically regulated in accordance with the specified CO2 content. Reducing the quantity of fresh air can also significantly reduce the refrigeration level required when transporting fruit. An automatic fresh air flap also makes certain CA functions possible (see the chapter on "Controlled atmosphere").

  4. Research is still being carried out on new coolants, with a trend toward "natural" coolants, such as butane/propane, CO2 or water. It will of course be a long time before any of these coolants can be introduced into the refrigerated container sector.


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