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Bifurcation phenomena may be examined in terms of the class of non-linear differential equations of the first kind in the formx(t) = α n βx(t) - {x(t)} n+1 ,where α and β are constants and n is an integer. A transformation of variables is applied taking into account the initial values x(0) = x 0 . The solutions are presented in the form of dimensionless variables...
The overall thermal transfer value (OTTV) concept has been extended to correlate it with the chiller load through DOE-2 computer simulations. A survey of 83 commercial buildings completed between 1982 and 1992 indicates that about one-third of the existing building-envelope designs will not meet a proposed 35W/m 2 OTTV limit, which will be introduced in late 1994. Impacts of this legislation...
A comprehensive approach that considers fuel, fodder and fertiliser relationships has been used to analyse the rural energy system of Karnataka. A linear programming model that incorporates these relationships has been used to simulate and study the effects of various policy options on the rural energy system in 2000 A.D. Increased efficiency of non-commercial fuel use and provision for improved...
A computer simulation program is used to predict the performance of a solar thermosyphon domestic water heating system. The model has a standard configuration with 4 m 2 of solar panels and a 250 l geyser which may be either vertical or horizontal. Typical meteriological year 15 min solar insolation data for the Pretoria area and corresponding ambient and cold water temperatures are used...
Available methods for estimating chemical energies and exergies of fuels are described and the results compared. One of the procedures is recommended for practical application in improved form.
A Workshop was organized for the purpose of receiving expert inputs on basic research in support of industrial applications of combustion systems. The output of this Workshop is here summarized.
A method of pricing electricity (allowing for operating costs, capital costs and taxes) is developed in which debt repayments are discounted at a separate rate from the returns on equity capital. There result but small numerical differences from a method developed by Williams [Ann Rev. Energy 3, 313 (1978)] using a weighted overall discount rate.
We update the technical status of wood feedstock production and highlight areas where the technology used to produce energy crops has changed since publication of an earlier paper. Most of the research findings presented earlier still hold, but the target dates for achieving them are in the distant future. We estimate current delivered costs in the range of about $2.30/GJ in the Pacific Northwest...
A novel, two-step, water-splitting cycle is presented which, in contrast to previously proposed cycles that require upper operating temperatures above 2300 K, can be conducted at a moderate temperature. In the first endothermic step, Ni 0.5 Mn 0.5 Fe 2 O 4 is thermally activated above 1073 K to form an oxygen-deficient ferrite. In the second step,...
We present a technique for optimization of natural-convection, solar driers. The physical simulation is combined with a cost prediction and a search technique, which finds the constrained minimum of total cost per unit moisture removal. The optimum design for typical Bangladesh conditions is a relatively long collector, a thin grain bed and negligible chimney height. Sensitivity analyses have shown...
The optimal performance of a two-stage endoreversible combined cycle is investigated for steady-state operation. The cycle efficiency at maximum specific power output equals the Curzon-Ahlborn efficiency, whereas the maximum specific power output of the cycle is, in general, smaller than that of a single-stage endoreversible cycle operating over the same temperature range. Optimization problems...
We present a taxonomy and analysis of public policies that address the environmental impacts of power production. The paper consists of two parts. The first is a classification of policy options, including command-and-control regulations, emission caps, taxes, marketable permits, emission adders, and environmental performance standards along with a review of recent developments. Examples are drawn...
The Rankine cycle is a thermodynamic cycle that is particularly suited for generating electricity from heat. A Rankine cycle with water as the working fluid is the most frequently used process for large-scale electricity generation. For electricity production from low-temperature heat (up to about 400°C), the use of water is less suitable than that of organic media (organic Rankine cycle, ORC)....
This is a summary report on the commercialization status for stationary-power applications of phosphoric acid, molten carbonate, solid oxide, and polymer electrolyte membrane fuel cells.
India will require increasingly higher energy inputs for future industrial and economic development. Overall growth of energy consumption will result in substantially higher emissions of CO 2 . We present emission rates of CO 2 based on India's actual fuel consumption. It is estimated that use of non-conventional energy sources could reduce India's energy-related CO 2 emissions...
We present a method for determining the thermodynamic effectiveness of energy use in individual processes, large-scale productions and the national economy as a whole. The theoretically required minimal energy/exergy consumption is used to calculate process effectiveness in energy-consuming branches. Applications include processes involving chemical transformations, deformation in rolled-stock production,...
The construction sector accounts for the highest share (17%) of CO 2 emissions by final demand in the Indian economy because it uses highly energy-intensive materials and the need for shelters is very high. This sector is highly vulnerable to changes in pricing structure. Various construction techniques have been analysed and it is shown that a room of length 3.5 m, breadth 3.5 m and height...
This study deals with optimization of an AARS operating with a low-temperature heat source. Of 11 design variables chosen, five affect the cost significantly.
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