R134a and R407C
These refrigerants are primarily used for air conditioning and have replaced R22 in many applications. R134a has a relatively low pressure and therefore about 50% larger compressor displacement is required when compared to R22, and this can make the compressor more costly. Also larger tubing and components result in higher system cost. R134a has been very successfully used in screw chillers where short pipe lengths minimize costs associated with larger tubing. R134a also finds a niche where extra high condensing temperatures are needed and in many transport applications.
R407C is a zeotropic mixture consisting of 23% R32, 25% R125 and 52% R134a. It has properties close to those of R22, and is for this reason has seen extensive use in Europe due to rapid R22 phase out. Its glide and heat transfer properties generally penalize the system performance, although counter flow heat exchange can deliver some benefit with plate heat exchangers.
Posted in Refrigeration and Air Conditioning