Limitations and challenges of heat transfer enhancement techniques in solar thermal collectors: A review

Nowadays, there is wide acceptance among core energy experts and the research community that solar collectors have a critical role to play in the renewable energy sector. With the high-energy conversion rate associated with this solar energy harvesting technology, there is an urgent need to review various ways through which the heat transfer process can be improved. Researchers have mainly focused their attention on working fluid enhancement, thereby neglecting other techniques that can equally contribute to the heat transfer enhancement process in solar collectors. This has made studies in other directions obsolete. The primary objective of the present study is to provide an up-to-date overview of the latest advancements and novel approaches in enhancing the heat transfer process in solar collectors. Both conventional and innovative techniques were investigated, exploring their effectiveness in enhancing thermal performance and overall system efficiency. A comprehensive literature review of recent studies on heat transfer enhancement techniques in solar collectors was undertaken. Key challenges, knowledge gaps, and limitations were identified, and potential future research options were recommended. This holistic review will serve as a guide for researchers and key energy players, providing insight into the avalanche of research options available in the field of solar thermal collectors.