Vision article: Recent progress, challenges and perspectives on boiling, condensation, solidification and related phase-change thermal phenomena

• Advances in phase-change heat transfer through high-fidelity experiments and models. • Key challenges in predictive modelling, advanced diagnostics, and surface durability. • Integration of passive and active enhancement strategies is needed for future systems. • Emerging opportunities in cryogenic, microgravity, and sustainable thermal applications. • Vision for validated multiscale models to accelerate design of next-generation technologies This vision article accompanies a Special Issue of Applied Thermal Engineering dedicated to the 9th European Thermal Sciences Conference (EUROTHERM 2024), held in Bled, Slovenia, from 10 to 13 June 2024. The conference brought together 348 participants from 34 countries and featured eight plenary lectures, seven special sessions, and 234 peer-reviewed proceedings. From this broad programme, thirteen articles were selected and extended for publication in this Special Issue. These articles, in line with general developments in the field, feature advances in boiling, condensation, spray cooling, freeze-drying, and relevant multiphase flows. Collectively, these contributions highlight recent advances in the community, which include the development and deployment of high-resolution experimental diagnostics and high-fidelity simulations aimed at advancing our mechanistic understanding of important thermal-fluid phenomena, and enabling accurate and reliable predictions for component and system design. Looking forward, further progress will require breakthroughs in several areas, including the development of predictive and validated models across scales, the demonstration of long-term robustness of materials and surfaces under realistic operating stresses, and the integration of both passive and active enhancement strategies to meet increasingly demanding operating conditions. By synthesizing the state of the art and outlining key challenges, this article provides a forward-looking perspective for scientists, researchers and engineers, and identifies promising directions for future research and innovation in multiphase heat transfer.