Analogue mechanism technique for ribbed cylindrical shell roof

An analogue mechanism method, based in principle upon Newmark's spring bar mechanism technique, for the elastic analysis of rib-stiffened cylindrical barrels is presented. The shell column interaction is taken into account. Numerical solutions obtained for representative problems and their comparison, whenever possible, to existing solutions are presented. Experimental results obtained from a sand-cement model is presented in order to demonstrate the reliability of this method for predicting stresses in shell problems where there are no analytical solutions available for comparison.     

Evaluation of oxygen as oxidant in coal fired open cycle MHD-steam power plants

This study compares the thermal efficiency and economics of using oxygen rather than air as the oxidant in large coal-fired MHD-steam energy conversion plants, using a computer model to calculate thermal efficiency. The systems compared are a coal-air system with a thermal input of 2000 MW_th and two coal-oxygen systems, one with an input of 2000 MW_th and one with 6600 MW_th. The paper describes the process; compares flame temperature, electrical conductivity, and specific enthalpy; and presents Mollier diagrams for the two systems. At an oxidant preheat temperature of 1644 K, the net thermal efficiency of the coal-oxygen system is 8 to 9 percentage points lower than that for the coal-air system, if the power required to produce the oxygen is taken into account; however, despite its lower thermal efficiency, the coal-oxygen system has a lower cost of electricity. At a preheat temperature of 1644 K, the cost advantage is small, but at temperatures below 1200 K, the cost advantage is significant.     

Multi-Prandtl correlating equations for free convection heat transfer from a horizontal tube of elliptic cross-section

Steady laminar free convection from a horizontal elliptic cylinder set in unbounded space is studied numerically under the assumption of uniform surface temperature. A specifically developed computer-code based on the SIMPLE-C algorithm is used for the solution of the mass, momentum and energy transfer governing equations. Simulations are performed for ratios between the minor and major axes of the elliptic cross-section of the cylinder in the range between 0.05 and 0.98, inclination angles of the major axis of the elliptic cross-section with respect to gravity in the range between 0° and 90°, Rayleigh numbers based on the major axis of the elliptic cross-section in the range between 10 and 10⁷, and Prandtl numbers in the range between 0.7 and 700. It is found that the heat transfer rate increases with increasing the Rayleigh and Prandtl numbers, while decreases with increasing the orientation angle of the cross-section of the cylinder, i.e., passing from the slender to the blunt configuration. In addition, a noteworthy fact is that in most cases the amount of heat exchanged at the cylinder surface has a peak at an optimum axis ratio which is practically independent of the Prandtl number, while may either increase or decrease with increasing the Rayleigh number depending on whether the orientation angle of the tube is above or below a critical value of approximately 67.5°. Dimensionless correlating equations are proposed both for the optimum axis ratio for maximum heat transfer and for the heat transfer rate from the cylinder surface to the undisturbed surrounding fluid reservoir.     

Economic and environmental benefits of landfill gas from municipal solid waste in Malaysia

Discharge of Green House Gases (GHGs) and the management of municipal solid waste (MSW) continue to be a major challenge particularly in growing economies. However, these are resources which can be converted to green energy. Landfill gas which is essentially methane (50–55%) and carbon dioxide (40–45%) (both GHGs) is released from MSW by biodegradation processes. The estimation of this methane and its economic and environmental benefits for environmental sustainability are the objectives of this study. Methane emission from MSW disposed of in landfills was estimated using Intergovernmental Panel on Climate Change (IPCC) methodology. From the study, based on 8,196,000 tonnes MSW generated in Peninsular Malaysia in 2010, anthropogenic methane emission of about 310,220 tonnes per year was estimated. This was estimated to generate 1.9 billion kWh of electricity year^?1 worth over RM 570 million (US$190 million). In addition, this leads to carbon dioxide reduction of 6,514,620 tonnes year^?1 equivalent to carbon credit of over RM 257 million (US$85 million). These results were also projected for 2015 and 2020 and the outcomes are promising. Therefore, the exploration of this resource, besides the economic benefits helps in reducing the dependence on the depleting fossil fuel and hence broadening the fuel base of the country.     

Effect of hydrogen addition using on-board alkaline electrolyser on SI engine emissions and combustion

In this study, an electrolyser was used to supply hydrogen to the SI engine. Firstly, the appropriate operation point for the electrolyser was determined by adjusting the amount of KOH in the electrolyte to 5%, 10%, 20% and 30% by mass, and applying 12 V, 16 V, 20 V, 24 V and 28 V voltages. Tests were first carried out with the gasoline without the use of an electrolyser, followed by operating the electrolyser at the appropriate point and sending obtained H₂ and O₂ to the engine in addition to the gasoline. The SI engine was operated between 2500 rpm and 3500 rpm engine speeds with and without hydrogen addition. Cylinder pressure, the amount of gasoline, H₂ and O₂ consumed by the engine and the emission data were collected from the test system at the aforementioned engine speeds. Furthermore, indicated engine torque, indicated specific energy consumption, specific emissions and HRR values were calculated. According to the results obtained, improvement in ISEC values was observed, and CO and THC values were improved by up to 21.3% and 86.1% respectively. Even though the dramatic increase in NO_x emissions cannot be averted, they can be controlled by equipment such as EGR three-way catalytic converter.     

Fatty acid accumulation in the different fractions of the developing corn kernel

In the food industry, the use of the oil is determined by the composition of fatty acids, and this is highly dependent on its natural origin. The fatty acid composition of whole corn kernel was determined in three varieties of corn (Astro, GH2547, and Local). Linoleic acid was the predominant fatty acid in the oil of Astro and Local at all collection dates, whereas it was the major fatty acid in the oil of GH2547 only between 40 and 60 days after pollination (DAP). The fatty acid accumulation in the endosperm, pericarp and germ fractions of the corn kernel during maturation was determined. The accumulation pattern of oil content was different in these three kernel fractions. The highest levels of oil content in the endosperm (2.2%), germ (34.3%) and pericarp (10.8%) fractions were detected at 20, 40 and 30 (DAP), respectively. The fatty acid accumulation patterns were different amongst the analysed kernel parts, indicating a numerous differences between the three corn kernel parts. Throughout the sampling periods, the endosperm fraction was distinguished by the highest and the lowest levels of oleic and linoleic acids, respectively. At all stages of kernel development, the pericarp fraction had the highest levels of total polyunsaturated fatty acids, which has numerous healthy applications. These results may be useful in the understanding of the potential source of the beneficial unsaturated fatty acids amongst the different fractions of the corn kernel during maturation.     

Evaluating the efficiency of divestiture policy in promoting competitiveness using an analytical method and agent-based computational economics

Choosing a desired policy for divestiture of dominant firms’ generation assets has been a challenging task and open question for regulatory authority. To deal with this problem, in this paper, an analytical method and agent-based computational economics (ACE) approach are used for ex-ante analysis of divestiture policy in reducing market power. The analytical method is applied to solve a designed concentration boundary problem, even for situations where the cost data of generators are unknown. The concentration boundary problem is the problem of minimizing or maximizing market concentration subject to operation constraints of the electricity market. It is proved here that the market concentration corresponding to operation condition is certainly viable in an interval calculated by the analytical method. For situations where the cost function of generators is available, the ACE is used to model the electricity market. In ACE, each power producer’s profit-maximization problem is solved by the computational approach of Q-learning. The power producer using the Q-learning method learns from past experiences to implicitly identify the market power, and find desired response in competing with the rivals. Both methods are applied in a multi-area power system and effects of different divestiture policies on market behavior are analyzed.