Use of zeotropic blends in flooded refrigeration loops: consequences and limits.

In response to phasing out of HCFCs and to phasing down of HFCs with high GWP, the chemistry industry proposes a large panel of low GWP blends of HFC or HFC-HFOs. These blends are tailored in order to ensure a best compromise between themophysical properties, technical properties and safety properties. This results in the proposition of a large list of blends, each of them having its own specific components and composition. One of the common characteristics of these tailored blends is their zeotropic behaviour. This particularity tends to prevent their utilization in industrial refrigeration where liquid vapour separators (MP, LP) are often used. But in regard to the number of candidates to replace pure HCFC (mainly R22) or high GWP HFC blends (mainly R507A and R404A), the problem of the use of zeotropic blends in these applications is to be addressed. In this context, the present paper proposes to study the behaviour of zeotropic blends in flooded refrigeration loops. This behaviour is assessed by using Refprop software V8. The difference between calculation made with taking into account the fractionation of the fluid and the calculation made without taking this fractionation into account will be highlighted. A single stage flooded system is investigated. The impact of the temperature glide on the performances of this system will be assessed with fluids proposed for R22 replacement (for instance RS 45). Fluids with higher glide will also be assessed (for instance, R407F) as well as the effect of the evaporating temperature on the phenomenon.