Advances, limitations, and research opportunities in indirect evaporative cooling systems: a systematic and critical literature review

The growing demand for low-energy and climate-resilient cooling has renewed interest in conventional indirect evaporative cooling (IEC) and dew-point indirect evaporative cooling (DPIEC) systems as alternatives to vapor-compression refrigeration. However, existing studies remain fragmented across geometries, materials, modeling approaches, and operating conditions, making it difficult to identify robust design principles and persistent barriers to practical deployment. This paper presents a Systematic and Critical Literature Review (SLR) of 252 primary studies published between 1992 and 2025. Following a transparent review protocol, the study examines conventional and dew-point IEC configurations with emphasis on three analytical dimensions: (i) technological and methodological advances, (ii) recurring gaps and limitations, and (iii) opportunities for future research and innovation. The synthesis highlights substantial progress in water management, surface wettability and coatings, porous and membrane-based materials, advanced exchanger geometries, and multiphysics modeling supported by artificial intelligence and optimization. At the same time, major gaps remain in long-term reliability, water-use assessment, condensation control, standardized testing and boundary conditions, techno-economic and environmental assessment, and full-scale validation under diverse climatic conditions. By integrating thermodynamic, hydraulic, material, and modeling perspectives, this review provides a consolidated framework and research roadmap to support the scalable, sustainable, and climate-responsive deployment of IEC technologies.