RESUMO
The rapid increase in energy consumption around the world is the main challenge that compromises and affects the environment. Electricity generation, which mainly depends on fossil fuels, produces around 80% of CO2 emissions released into the atmosphere. Renewables are a remarkable alternative for energy production. However, they are intermittent sources of energy. Liquid air energy storage (LAES) is a medium-to large-scale energy system used to store and produce energy, and recently, it could compete with other storage systems (e.g., compressed air and pumped hydro), which have geographical constraints, affect the environment, and have a lower energy density than that of LAES. However, the low efficiency, high payback periods, and profit values of LAES hamper its commercialization. LAES is premature to be fully studied because lack of actual operating conditions and results from large plants, which affect the techno-economic predictions, in turn, affecting technology commercialization. Furthermore, the off-design conditions are not fully covered although it is a crucial step in system performance evaluation. To this end, the current mini-review sheds light on the LAES design, history, types, limitations, and the associated techno-economic analysis. In addition, state-of-the-art modelling tools are widely explained with benefits and shortage. Furthermore, LAES integration with other systems is explained widely, as it was found to boost the system performance and increase the profit with lower payback periods.
RESUMO
The desiccant air conditioning system has multiple advantages (e.g., no use of ozone-depleting refrigerants, highly efficient moisture control, easy regenerative integration) over traditional vapor-compression refrigeration systems, thus increasingly attracting more research interest. Recently, several studies have been conducted that primarily aimed to enhance the overall performance of desiccant air conditioners by innovating new desiccant materials, innovating new system configurations and improving system designs and controls, and integrating different hybrid energy sub-systems technologies. Therefore, this paper provides a comprehensive review of the studies mentioned earlier. The present comprehensive review dealt with several axes: first, an overview of the importance of using desiccant air conditioners and their operations, and performance indicators. Second, a summary statement for desiccant materials that includes: the new innovative desiccant materials and the most important composite desiccant materials. Third, detailed information on the newest innovative designs and configurations of desiccant air conditioning systems and their control systems. Fourth, a detailed statement on the most important hybrid energy sub-systems technologies integrated with desiccant air conditioners. Based on the latest developments in desiccant air conditioning systems, this study presents discussions of urgent issues and recommendations for future work that can help focus necessary efforts to find solutions to critical and pending problems, which lead to further improvements in the overall performance of desiccant air conditioners.
