R723 - a mixture of 60% ammonia and 40% dimethyl ether - has become interesting as an environmentally friendly refrigerant for many companies and institutions. In times of continuously increasing interest in the environmentally friendly use of resources, refrigeration technology is also looking for sustainable alternatives - yet, according to the Federal Environment Agency, it accounts for 14% of the total energy demand in Germany.
R723 has been developed in several years of research. The name results from its assignment to the natural refrigerants (series 700) and its average molecular weight of 23g / mol. The mixture is a colourless, liquefied gas with a sharp odour. By mass, R723 consists of 60% of ammonia and 40% of dimethyl ether, a propellant. The mixture shows azeotropic boiling and condensation behaviour. This means that no concentration shift occurs during evaporation and condensation and the mixture can not be separated by simple distillation. It behaves like a pure substance and can therefore be handled like a single-substance refrigerant.
Ammonia dimethyl ether is a 100 percent natural refrigerant. Although ammonia is produced synthetically for use in the refrigeration process, it is regarded as a natural substance because it occurs in the material cycles of the earth. Ammonia has been proven in industrial refrigeration for a long time and is a very good refrigerant in terms of climate, as it does not contribute to the depletion of the ozone layer or the greenhouse effect. Ammonia is efficient and leads to lower operating costs of the systems. R723 is even more efficient: The mixture has a greater volumetric refrigeration power than ammonia. For this reason, it can realize much larger refrigeration power with the same capacity. This is particularly clear in a direct comparison in refrigeration systems, which were initially operated with ammonia and then with R723. Here, an improvement of the COP value (Coefficient of Performance) of 7% was achieved. Regarding toxic effects, the information applicable to ammonia must be observed. Specific toxicological effects of the additive component dimethyl ether are not known.
Basically, ammonia refrigeration systems can be filled and operated with R723. However, consideration should be given to the individual applications. The material compatibility is identical with ammonia. Nevertheless, the conversion should always be confirmed with the corresponding component manufacturers. The energy efficiency of the substance mixture is complemented by a high coefficient of performance and high oil solubility. Another advantage results from the lower compression end temperature. This allows piston compressors to sensibly reach a greater temperature swing.
R723 is not only ecological, but also economically sustainable. Compared to synthetic refrigerants, it can be classified as inexpensive in term of purchase costs. The saving is not only noticeable in the initial filling of the system, but especially in the low leakage losses, that is the weight loss due to evaporation or leakage due to, for example, a leak. In addition to the low cost of leakage and the efficiency already described, R723 also carries relatively low disposal costs at the end of the runtime.