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A thermoelectric generator (TEG) device which uses solar energy as heat source would achieve higher efficiency if there is a higher temperature difference between the hot-cold ends. However, higher temperature or higher heat flux being imposed upon the hot end will cause strong thermal stress, which will have a negative influence on the life cycle of the thermoelectric module. Meanwhile, in order to get high heat flux, a Fresnel lens is required to concentrate solar energy, which will cause non-uniformity of heat flux on the hot end of the TEG and further influence the thermal stress of the device. This phenomenon is very common in solar TEG devices but seldom research work has been reported. In this paper, numerical analysis on the heat transfer and thermal stress performance of a TEG module has been performed considering the variation on the power of the heat flux being imposed upon the hot-end; the influence of non-uniform high heat flux on thermal stress has also been analyzed. It is found that non-uniformity of high heat flux being imposed upon the hot end has a significant effect on the thermal stress of TEG and life expectation of the device. Taking the uniformity of 100% as standard, when the heating uniformity is 70%, 50%, 30%, and 10%, respectively, the maximum thermal stress of TEG module increased by 3%, 6%, 12%, and 22% respectively. If we increase the heat flux on the hot end, the influence of non-uniformity on the thermal stress will be more remarkable. [ABSTRACT FROM AUTHOR]

Abstract: Numerical simulations have been carried out on the solar chimney power plant systems coupled with turbine. The whole system has been divided into three regions: the collector, the chimney and the turbine, and the mathematical models of heat transfer and flow have been set up for these regions. Using the Spanish prototype as a practical example, numerical simulation results for the prototype with a 3-blade turbine show that the maximum power output of the system is a little higher than 50kW. Furthermore, the effect of the turbine rotational speed on the chimney outlet parameters has been analyzed which shows the validity of the numerical method advanced by the author. Thereafter, design and simulation of a MW-graded solar chimney power plant system with a 5-blade turbine have been presented, and the numerical simulation results show that the power output and turbine efficiency are 10MW and 50%, respectively, which presents a reference to the design of large-scale solar chimney power plant systems. [Copyright &y& Elsevier]

Power stations, ships and air traffic are among the most potent greenhouse gas emitters and are primarily responsible for global warming. Iron salt aerosols (ISAs), composed partly of iron and chloride, exert a cooling effect on climate in several ways. This article aims firstly to examine all direct and indirect natural climate cooling mechanisms driven by ISA tropospheric aerosol particles, showing their cooperation and interaction within the different environmental compartments. Secondly, it looks at a proposal to enhance the cooling effects of ISA in order to reach the optimistic target of the Paris climate agreement to limit the global temperature increase between 1.5 and 2 °C. Mineral dust played an important role during the glacial periods; by using mineral dust as a natural analogue tool and by mimicking the same method used in nature, the proposed ISA method might be able to reduce and stop climate warming. The first estimations made in this article show that by doubling the current natural iron emissions by ISA into the troposphere, i.e., by about 0.3 Tg Fe yr-1, artificial ISA would enable the prevention or even reversal of global warming. The ISA method proposed integrates technical and economically feasible tools. [ABSTRACT FROM AUTHOR]

Power stations, ship, and air traffic are among the most potent greenhouse gas emitters and primarily responsible for global warming. Iron salt aerosols (ISA) exert a cooling effect on climate in several ways. This article aims firstly to examine all direct and indirect natural climate cooling mechanisms driven by tropospheric aerosol particles composed partly of iron and chloride, showing their cooperation and interaction within the different environmental compartments. It then looks at a proposal to enhance the cooling effects by ISA in order to reach the CoP 21 optimistic target level of a global temperature increase of between 1.5 and 2 °C. Using mineral dust as a natural analogue tool, the proposed ISA method might be able to reduce climate warming by mimicking the same method used by nature during the glacial periods. The first estimations made in this article show that by doubling the current natural ISA emissions into the troposphere, i.e. by about 0.3 Tg Fe per year, artificial ISA would enable the prevention or even reversal of global warming. The ISA method proposed integrates technical and economically feasible tools. [ABSTRACT FROM AUTHOR]

Abstract: On the basis of field synergy principle for heat transfer enhancement, physical quantity synergy in laminar flow field of convective heat transfer is analyzed according to physical nature of convective heat transfer between fluid and solid wall. Synergy regulation among physical quantities is revealed by mathematical expressions reflecting mechanism of heat transfer enhancement. Characteristic of heat transfer enhancement, which is directly associated with synergy angles α, β and γ, is also analyzed. Numerical simulation is made to verify the principle of physical quantity synergy developed in the paper. [Copyright &y& Elsevier]

The article introduces topics covered in the issue including energy efficiency, global economic growth, and smart waste disposal.