Rechargeable batteries have gained a lot of interests due to rising trend of electric vehicles to control greenhouse gases emissions. Among all type of rechargeable batteries, lithium air battery (LAB) provides an optimal solution, owing to its high specific energy of 11,140 Wh/kg comparable to that of gasoline 12,700 Wh/kg. However, LABs are not widely commercialized yet due to the reactivity of the lithium anode with the components of ambient air such as moisture and carbon dioxide. To address this challenge, it is important to understand the effects of moisture on the electrochemical performance of LAB. In this review, the effects of ambient air on the electrochemical performance of LAB have been discussed. The literature on the deterioration in the battery capacity and cyclability due to operation in ambient environment and degradation of lithium anode due to exothermic reaction between lithium and water is reviewed and explained. The effects of using oxygen-selective membrane (OSM) to block moisture and $${\mathrm{CO}}_{2}$$
CO
2
contamination has also been discussed, along with suitable materials that can act as OSM. It is concluded that the utilization of OSM can not only make the safer operation of LAB in ambient air but could also enhance the electrochemical performance of LAB. Future direction of the research work required to address the associated challenges is also provided.
To achieve higher operating temperatures, power output and system efficiencies in parabolic dish cavity receivers, larger dish sizes and structures are used to increase the concentration ratio. This increases capital investment and installation costs, which in turn places a much stronger emphasis on accurately predicting the performance of the system and the heat loss from it. Numerous studies have investigated the natural convection heat losses from cavity receivers, and some have examined a cavity exposed to wind. However, the effect of the dish on the wind flow and subsequently the heat loss from the receiver has not been widely considered.In this work, computational fluid dynamics was used to model the flow of air around a parabolic dish concentrator operating at varying angles of operation. The flow fields were validated using wind tunnel testing and published data regarding the aerodynamic characteristics of parabolic dishes. The results showed that the orientation of the dish has a significant effect on the flow structure near the receiver. Subsequently, using the validated method, the convective heat loss from the receiver of a large parabolic dish system was determined for a range of operating conditions.The results support the assertion that the flow characteristics near the cavity receiver aperture depend strongly on the orientation of the dish structure. This resulted in the calculated heat loss being up to 40% lower than previous studies where the presence of the dish was included. As such, the wind flow around the dish needs to be accounted for when analyzing the performance of parabolic dish systems to avoid an overly conservative and hence more expensive design.
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