Seasonal performance optimisation of thermally driven ejector cooling cycles working with R134a

•CFD model is applied to analyse the performance of single-phase ejectors with R134a.•A multi-objective optimisation algorithm is used to improve the ejector performance.•Four ejector cooling cycles are compared against the basic cycle through the SEPR.•Geometrically optimised ejectors are a must to achieve the desired performance.•A thermally-driven sub-cooler with ejector improved the SEPR up to 23%.