A design method of turboexpander-compressors based on multi-objective optimization applied to reverse brayton cycle

Abstract

This paper presents a new design method for turboexpander-compressors used in air refrigeration. As a key component of the reverse Brayton cycle, the efficiency of the turboexpander-compressor significantly has an impact on the overall cycle performance. The expander section is optimized for multi-objective efficiency at different flow rates using the Imperialist Competitive Algorithm to achieve high performance across all operating conditions. Regarding achieving high utilization efficiency for output power from efficient expanders, the compressor section adopts combined methods involving the jet-wake model and parameter equations. The proposed design is validated through public models, computational fluid dynamics simulations and experiments. Simulations and analysis are conducted on test cases representing comprehensive operational scenarios for both the compressor and the expander, confirming that conclusions drawn based on this method align well with underlying theoretical principles. At the design mass flow, the expander efficiency is 89%, and the compressor utilizes the output power of the expander with an efficiency of 90%. Near the design flow, the expander efficiency is more than 85%, and the compressor utilizes the output power of the expander with an efficiency exceeding 80%. This paper presents a method for turboexpander-compressors applicable to air refrigeration cycles, which achieves a reduction in design costs and an improvement in efficiency under varying loads.