What is the best natural refrigerant and what is the best system?

The objective of this paper is to assist people with the fundamental decision of which natural refrigerant is the best choice for a given application. The application is governed by process temperatures and the end user’s acceptance criteria (toxicity and flammability risk). The paper has been structured so that it is user friendly and delivers answers quickly. The assumptions and further explanations are given at the end of the paper for reference. The scope of the paper has been restricted to primary refrigerants in industrial refrigeration systems between 100 kW and 10 MW using natural refrigerants in vapour compression cycles.