Dearman’s Zero Emission Mobile Refrigeration System On Trial In South Africa

NEWS & MEDIA | 09 October 2018

Dearman’s Zero Emission Mobile Refrigeration System On Trial In South Africa

Dr Daniel Fennell of Dearman UK recently confirmed that Dearman is well into a two year project to provide mobile precooling for crop harvesting in the Gauteng area.

The pre-coolers are driven to the field and provide rapid cooling to preserve quality. Post -harvest spoilage in the fruit and vegetable sector costs South Africa billions per year and losses in Africa as a whole are horrendous. An objective of the project is to make similar pre-coolers available to emerging farmers.

The refrigeration system uses the Dearman motor which runs on liquid nitrogen producing none of a diesel engine’s nitrogen oxide and carbon dioxide gases, noise or waste heat.

 

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The system works by initially allowing the liquid nitrogen to expand becoming a gas. This absorbs heat from the chilled area.  the gas is then combined with a warm water/glycol mixture in the motor which provides the necessary pressure to operate the pistons. The water /glycol mixture is recycled while the nitrogen gas is vented to the air. The Dearman motor drives a secondary refrigeration system as well as generating sufficient electricity to power the evaporator fans and lights. It is expected that between 50 and 75% of the precooling will come from   nitrogen expansion and 25 to 50% from the secondary refrigeration.

 

One tank of liquid nitrogen will last for approximately two days and the pull down time from plus 15 to minus 21 degrees C is approximately 30 minutes once the door is closed.

 

Apart from in field pre-cooling, the Dearman motor looks set to revolutionize local refrigerated transport in the medium term. It won’t be long before mobile refrigeration units switch to this environmentally efficient method of cooling.

 

To learn more about Dearman click here.