Annual performance evaluation of a hybrid concentrated solar-micro gas turbine based on off-design simulation.

As the adoption of solar hybrid systems continues to rise due to their potential to compensate for the fluctuation of solar irradiation, it becomes imperative to accurately evaluate their performance, considering the variation of off-design conditions. This paper introduces a detailed analysis method for evaluating the annual performance of a solar-MGT system under transient boundary conditions for a whole-year operation range. A hybrid system of a micro gas turbine, recuperator, and solar dish is considered, and an off-design simulation model is developed and verified with available experimental results. Two different configurations for a recuperated cycle are considered, and simulations are conducted for a test case in Pretoria, SA. The results for Jun.21 and Dec.21 as low and high solar energy days are reported with more details to compare the configurations and demonstrate the effect of ambient temperature on the heat loss of the solar receiver and the overall performance of the system. The alternative configuration reduces heat loss with a lower temperature receiver but has higher fuel consumption compared to the conventional configuration. Operating strategies for different hours of operation from 1 h to 24 h per day are simulated for 365 days, based on real meteorological data, and compared with the operating in solar available hours. It is shown that the whole-year simulation of the system considering the variation of boundary conditions can change the estimation of fuel consumption by 25 %.

Effect of lead on proliferation and neural differentiation of mouse bone marrow-mesenchymal stem cells.

Bone marrow-mesenchymal stem cells (MSCs) are considered to be an ideal source of stem cells for assessing the effects of environmental toxins on the proliferation, multipotency and differentiation of adult stem cells. The aim of this study was to investigate the effect of lead on the proliferation and neuronal differentiation of murine MSCs. MTT assay used in this study revealed that while the proliferation of MSCs is sensitive to higher than 10 microM lead, a 50% reduction in the rate of their proliferation can be achieved in the presence of 60 microM lead. The results of immunocytochemistry and RT-PCR showed that beta-mercaptoethanol induced-neuronal differentiation is also reduced after the treatment of MSCs by 60 microM lead. Furthermore, the comet assay analysis of MSCs showed a substantial increase in DNA damage in the lead treated cells compared to the control. In conclusion our results revealed for the first time that lead is not only cytotoxic to the survival and proliferation of MSCs but also inhibits their differentiation to neurons in a dose-dependant manner. Therefore, MSCs appear to be an alternative method for assessing the cytotoxic effects of such environmental hazards.