Renewable and waste heat applications for heating, cooling, and power generation based on advanced configurations

Abstract

Using renewable heat energy sources, recovering the waste heat, and enhancing the processes and energy efficiency can reduce the electricity dependency of several industrial applications. Renewable and waste heat have a low-grade enthalpic level and should be combined with other technologies to bring it to a practical level. This could be achieved by increasing the variety of heat sources and their combinations (multi-function systems), resulting in a high overall energy performance and reducing greenhouse gas emissions. Recent research on this topic has been conducted considering solar-assisted geothermal heat pumps (single and combined), low-grade waste heat, organic Rankine-vapour compression cycles (ORC-VCC), and absorption refrigeration. In the current research, comprehensively review of the state-of-the-art advanced arrangements using renewable heat sources and waste heat utilisation for simultaneous heating, cooling, and power generation was performed. To the best of the author’s knowledge, the use of waste heat from VCC systems represents one of the most promising technologies in the future. Solar and geothermal heat pumps are considered for different applications and at different temperatures, presenting a high coefficient of performance. However, their utilisation is beneficial only when both renewable heat sources are considered. Although both the ORC and ejector refrigeration systems demonstrated low thermal performance, the overall system performance remained similar to that of the original system. Absorption refrigeration is promising as an up-and-coming alternative to a VCC system, but it is often hampered by excessive cooling unit sizes and a low COP.