Investigation on a two-stage ejection refrigeration system

• A two-stage ejection refrigeration system is investigated experimentally.
• Performance of each ejector is investigated in the system.
• We conducted comparison between single-stage and two-stage system.
• The system can operate under the highest condensing temperature of 54 °C.
• Operational strategies are discussed for the different working conditions.

Working under high condensing or low evaporating temperatures, a two-stage ejection refrigeration system is presented in order to effectively utilize low-grade heat in this context. The performance of the two-stage ejection refrigeration system is investigated under generating temperatures from 130 to 150 °C, condensing temperatures of 45–54 °C and evaporating temperatures from 6 to 30 °C. The experimental results show that the presented two-stage ejection refrigeration system can operate normally under a condensing temperature of 54 °C, which is higher than the normal condensing temperatures of a single-stage ejection refrigeration system. However, the extra power input to drive the 2nd ejector make such a system less efficient under condensing temperatures below 50 °C. Under those circumstances, through adjustment of operational strategies, an ejection refrigeration system should choose using single-stage ejector or two-stage ejector for different operational conditions, which greatly extends the application range of ejection refrigeration systems.