Rapid urbanisation and rising thermal comfort expectations are propelling global energy demand for space cooling and heating in buildings, cementing vapour compression air conditioning as the dominant technology due to its proven simplicity and efficiency. However, conventional mechanical configurations remain constrained by intrinsic thermodynamic irreversibilities and by international protocols mandating the phase-out of high global warming potential refrigerants. While a growing body of research proposes performance-enhancement measures, these advances remain fragmented across technologies and application contexts. This paper critically reviews recent vapour compression cycle developments, structuring the literature around five interrelated thematic pathways: refrigerant-centric strategies, thermodynamic cycle modifications, hybrid system integration, heat exchanger innovations, and control-centric optimisations. The analysis reveals that no single technology can universally optimise vapour compression cycle performance; instead, effective system improvements emerge from context-specific combinations of refrigerant innovation, heat-transfer enhancement, cycle modification, and hybridisation, with the most successful strategies closely aligned to required temperature lifts and regional climatic conditions. This review introduces a simplified constraint–strategy–technology framework in which dominant system constraints (regulatory and proprietary, thermodynamic and climatic conditions, and demand-related) are first identified. Then corresponding technological improvement strategies (cycle modification, hybridisation, material selection, and control optimisation) are mapped out while enabling technologies are evaluated for suitability, scalability, and maturity. Therefore, this framework provides a system-level synthesis that links performance gains to context-specific operating constraints.
Khiro et al. (Thu,) studied this question.