Variable Mixing Chamber Waste-Heat Driven Ejector Cycle For Commercial Refrigeration

Egoï Ortego (1)

1 CES - Centre Efficacité Énergétique des Systèmes

Ejectors are commonly studied for heat-driven refrigeration systems. Constant mixing area ejectors are limited in cooling capacity because of the presence of a shocked flow in the mixing chamber in normal conditions. Besides, this geometric constraint makes ejectors extremely sensitive to the outlet pressure variations usually associated with ambient temperature variations; at high temperatures, ejectors can suddenly stall leading to zero power. The author developed a variable mixing chamber ejector concept that helps in reducing the drawbacks of ejectors. It makes it possible to increase the mixing chamber cross-sectional area at moderate temperatures and reduce it at high temperatures. This results in an extended range of operation. In this paper, the benefits of using this new ejector as a heat-driven compressor booster stage are quantified. The ejector-based booster stage can be driven by low grade heat or solar power. The variable mixing chamber ejector opening is adapted to the condensation temperature to maximize the entrained flow rate for every operating condition; this maximizes the cooling capacity whatever the condensation temperature is. New system architecture for commercial refrigeration is explored in the paper. The gains are computed by common thermodynamic models and a specific ejector reduced model derived from CFD modeling. The refrigeration efficiency gains of the studied architectures are compared to a classical vapor compression refrigeration system.

Domaines: Sciences de l'ingénieur [physics]

Egoï Ortego. Variable Mixing Chamber Waste-Heat Driven Ejector Cycle For Commercial Refrigeration. International Refrigeration and Air Conditioning Conference, Purdue University, Jul 2022, West Lafayette, United States. ⟨hal-03908564⟩