Reviewed in this paper are the methodologies used for emissions inventory preparation and the environmental impact evaluation of emissions from industrial production and/or technologies utilization. The methodologies utilized for emissions inventories can be categorized into two approaches: the bottom-up approach, and the analytical approach using input-output tables. Currently, the environmental impacts are evaluated by the classification, such as “Greenhouse effect” and “Ozone layer depletion”, and aggregation method, whose value are calculated by the product of the emissions volume/mass and the weighting factors. The weighting factors are presently estimated based on scientific knowledge as far as possible. In order to evaluate environmental impacts on the different classifications in the same unit, the method of the calculation of environmental costs has been the focus of attention recently. Environmental costs are the parts of the externality, which is not reflected on the present market prices, of the industrial products and/or technologies. In the future, we should consider not only environmental impacts caused by the emissions but also other externality such as “Resource depletion” and “Land use”.
The ash layer diffusion controlling model and a finite difference method were successfully employed to simulate a single char particle combustion at around ash melting temperature. The numerical modeling was conducted under the operation conditions similar to the author's previous experiment. It was found that the numerical temperature profile in a burning char particle was strongly influenced by the ash layer heat conductivity. By considering the ash layer heat conductivity was varied with time, the simulated particle time temperature profiles agreed well with the experimental results. And the optimum value of ash layer heat conductivity to fit the experimental temperature variation with time was found to be increased with ash content and maximum combustion temperature. The agreement between the simulation and experimental results proved the validation of the numerical modeling. The numerical study also suggested that the smaller particle reaches its peak temperature quicker than larger particles and gives the higher peak temperature.
In order to obtain some information on ignition property of diesel fuels, we have attempted to determine autoignition temperatures of various diesel fuels and to compare those with their cetane numbers. As a result it was shown that the autoignition temperature of the diesel fuels should have a tendency to decrease with an increase in their cetane number and that the addition of the cetane number improving agents could make autoignition temperatures lower. We suggest that the autoignition temperature test should be useful screening one to evaluate the cetane number and the cetane number improvement of diesel fuels.