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The production of metals and synthesis gas are major consumers of high-temperature process heat and are responsible for about 10% of the total global anthropogenic CO 2 emissions to the atmosphere. These emissions can be substantially reduced by combining the reduction of metal oxides with the reforming of natural gas and by replacing fossil fuels with solar energy as the source of process...
Direct conversion of methane to methanol with minimum energy consumption could become a key technology for highly efficient utilization of fossil fuel, because low-quality or low-temperature (∼ 100°C) energy sources can be used and regenerated by converting methanol to hydrogen. For this purpose, a new technique for synthesizing methanol directly from a methane-oxygen mixture has been developed using...
Preliminary design and stability analyses of magnetohydrodynamic (MHD) disk generators have been carried out. These are used in electric power-generation systems with CO 2 recovery. Inflow disk channels show better performance than outflow disk channels. An inflow channel with supersonic flow shows an enthalpy extraction ratio of 20.2% when the thermal input is 1100 MW and the magnetic...
Coal combustion with CO 2 /O 2 is one of several promising new technologies associated with mitigating the CO 2 rise in the atmosphere. In coal combustion with recycled CO 2 , the amount of NO x exhausted from the system is reduced to less than one third of that with combustion in air. This result is associated with decreased conversion of fuel-N to NO ...
Pulverized coal combustion with oxygen and recycled flue gas constitutes a promising system to recover CO 2 from the exhaust gases of boilers. Our previous combustion tests on this system suggest emissions of smaller amounts of NO x than in conventional combustion and reduced ignition stability of the burner. In order to improve the combustibility of the O 2 /CO 2 ...
An ethanol production system, which is an integrated bioreaction for the production of ethanol from CO 2 , was developed. This system consists of biochemical and chemical reaction processes for the following: (i) photosynthetic CO 2 fixation and biomass production of cyanobacterium Synechococcus leopoliensis, (ii) HCl-catalyzed saccharification of cyanobacterial biomass to glucose,...
The IEA Greenhouse Gas R&D Programme is an international collaboration supported by 16 countries and several industrial organisations. Its purpose is to evaluate technologies for reducing emissions of greenhouse gases. The following are the findings of the first phase of its work: the most appropriate technology for capture of CO 2 depends upon the type of power plant and proven technology...
A new wet system to treat carbon dioxide in flue gas using water as an absorbent and soil as a cation-exchanger is proposed. The system consists of the following four processes. (i) Dissolution occurs of CO 2 from the flue gas into soil-containing water and is accompanied by formation of carbonate ions and an increase in the pH of the solution. Soil functions as a cation-exchanger because...
The very efficient hydrogenation of CO 2 in the presence of ethylene oxide has been catalyzed by soluble ruthenium complexes to obtain CO and ethylene glycol in good yields; over 70% of the CO 2 was converted into these products at 140-180°C, indicating that the reaction does not suffer from thermodynamic or kinetic restrictions at these reaction temperatures. The reaction mechanism...
Estimates of transition costs for U.S. investor-owned electric utilities range from $20 to $500 billion. These potential losses are a consequence of the above-market book values for some utility-owned power plants and long-term power-purchase contracts, as well as deferred income taxes, regulatory assets, and public-policy programs. Because of the wide range of estimates and the potentially large...
The natural convection heat transfer and ventilation characteristics of heated and vented parallel wall channels have been studied numerically. The flow is assumed to be laminar and steady, and the governing two-dimensional Navier-Stokes equations are solved by a finite volume formulation to calculate the chimney effect that draws cooler ambient air from the lower opening. The fluid-dynamic and heat-transfer...
We discuss the effects of turbine-blade cooling on HAT-cycle performance. The performance depends on the location for cooling by air bleeding; four possible locations have been explored. A parametric analysis was performed to verify pressure-ratio and turbine-inlet-temperature (TIT) effects. An exergetic analysis was used to clarify the differences between bleed-air point options and cycle-configuration...
A mathematical model has been developed for the exit-gas composition in a 10-MW fluidised bed coal-combustion power plant operated at Jamadoba. The model allows for bubble-size variation with height and predicts the consumption of O 2 , outlet-gas composition, variation of O 2 concentration in different phases, and also the average O 2 concentration along the bed height. ...
We present an analysis of an active winter greenhouse in terms of design and climatic parameters. The analysis is based on energy-balance equations for each system component. The effect of energy storage by a brick wall at the north side has been incorporated in the analysis. The proposed design is suitable for use under cold climatic conditions.
This study was motivated by its critical importance to the current problem of electricity supplies in Armenia. The time duration for oil-immersed power transformers in both operating (heating process) and standby (cooling process) regimes is determined for a given overloading degree. This process is compared with experimental results on TM-(630,400,250)10-0.4 kV transformers, and overloading times...
The exergy concept has been used to analyze two methane-fueled SOFC systems. The systems include preheating of fuel and air, reforming of methane to hydrogen, and combustion of the remaining fuel in an afterburner. An iterative computer program using a sequential-modular approach was developed and used for the analyses. Simulation of an SOFC system with external reforming yielded first-law and...
We present results of an analytic investigation on the influence of the thermal conductance of sorption elements (adsorber/desorber, evaporator and condenser) on the performance of a silica-gel-water advanced adsorption chiller, with consideration of the thermal capacitance ratio of the adsorbent and metal of the adsorber/desorber heat exchanger. The analysis was performed by using a cycle-simulation...
The problem of heat conduction in a two-dimensional orthotropic cylinder, subject to asymmetric and periodic temperature distributions on the outer wall, was solved analytically. The results depend on the non-dimensional frequency (α), outer to inner cylinder radius ratio (R 2 ), Biot number (Bi), and orthotropicity factor (K t ). Insulation characteristics of orthotropic cylinders...
We present the results of a dispersion-modelling study of SO 2 concentrations. Overall heat-transfer coefficients (U-values) of existing wall systems in Gebze, Turkey, have been measured. Different insulation options for improvement of the thermal performance of existing wall systems have been chosen. Comparative energy-consumption analyses for each option have been performed according...
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