Improving the energy efficiency of a light commercial application

For decades in the past there was no need for the industry to deliver very efficient commercial refrigerators and freezers. End customers did not ask for that, so at that time the most important argument was a low first cost.

Beginning with the discovery of the ozone layer depletion and the replacement of FKWs by HFKWs the environmental aspect came more into focus. The HFKWs with an ODP of zero still have a very high GWP value and they will be replaced more and more by natural refrigerants, namely HCs in commercial refrigerators and freezers.

When using HCs, the energy consumption is the only remaining factor for global warming. Starting in the household industry with the implementation of the Ecodesign requirements and Energy Labeling guideline, the EU required the industry to develop more and more energy efficient and therefore environmentally friendly products. Meanwhile, Ecodesign and Energy Labeling arrived in the light commercial industry.Supported by a new IEC 60335-2-89 which allows up to 500 g of HC refrigerants, a wide range of applications can be run with flammable refrigerants. The use of HCs can already improve the efficiency due to the good thermodynamical properties of these refrigerants.

To show which energy efficiency gains are possible on the component level, Danfoss performed tests on a typical application with a HFKW refrigerant. First, the compressor was replaced by a speed-controlled compressor, switching to R290 at the same time. Then, to increase the efficiency even more, a thermostatic expansion valve was installed instead of the capillary tube. The fin and tube condenser was replaced by a micro channel condenser to keep the refrigerant charge low, and finally an electronic controller was integrated to control the system in the most efficient way.