Focus on Sustainability: Using Water as a Refrigerant

In order to implement a functioning circular economy in its entirety in an ecologically sensible way, the CO2 emissions of the processing operations must be reduced in addition to increasing the recycling of plastics and the extensive use of recycled materials.

The basic problem of the plastics processing industry is a constantly necessary cooling requirement, mostly based on energy-intensive processes in combination with refrigerants that have a high greenhouse gas potential. Some plastics manufacturers now rely on water as a natural and, above all, CO2-neutral refrigerant in their cooling and refrigeration machines. For a functioning circular economy, it is not enough to optimise the material properties of the product in terms of sustainability. Extruders, injection moulding machines or even rollers – cooling plays a major role in the processing of plastics – it is even crucial for the overall quality that there are no major temperature fluctuations.

According to the International Institute of Refrigeration, eight per cent of global emissions are caused by the refrigeration industry alone, writes Angelika Thum of Efficient Energy in the trade journal ‘Plastverarbeiter’. By switching to natural refrigerants such as water, air, ammonia, propane or CO2, direct emissions could be almost completely avoided. The corresponding refrigeration technologies are available, have already been tested in industry and can now cover the entire refrigeration demand.

Water – a Natural and Unproblematic Refrigerant

Operators of refrigeration systems using water no longer have to deal with issues such as the greenhouse potential, toxicity or explosiveness of the refrigerant. From the point of view of energy efficiency, too, water has an advantage over F-gases (fluorinated greenhouse gases) because of its high heat of evaporation.

Legislation to reduce the CO2 equivalents of F-gases has led and is leading to some refrigerants being banned outright and others probably being changed several times in less than ten years. This results in bottlenecks, price increases, increased maintenance of existing plants and, in case of doubt, limited operational safety. In addition, F-gases have to be transported, stored, made available and disposed of. All these points are eliminated when using water and help companies reduce their carbon footprint.

From this point of view, the concept of ‘free cooling’ is also very interesting. In this free cooling system, the compressor typically used is reduced in speed or switched off completely when the outside temperature is low enough. This saves the energy required and reduces the operating costs of the refrigeration system even further.

Photo: visoot