Search

The combustion of natural gas consisted of methane CH4, ethane C2H6, and propane C3H8 is theoretically investigated to obtain the optimum adiabatic flame temperature (AFT). The investigation includes the development of combustion equations that take into consideration different compositions of natural gas. The final equation to calculate the AFT is derived and used in the optimization study. The optimization study using genetic algorithm investigates the effect of changing the composition of the gas mixture, the inlet temperature of used air, and the amount of excess air used on the AFT. It is possible to get the required composition of each component, the air inlet temperature, and the excess air by reading the chart to get the required AFT. The heat capacity of all reactants and products is used as a function of temperature. Results showed that the optimum values for CH4,C2H6,C3H8, percentages in the gas mixture, air inlet temperature, and the amount of excess air are 0.478, 0.166, 0.356 mol %, 1.848, 382.104 K, respectively. These optimum values lead to a value of about 1300 K for the AFT. The derived equation shows the AFT at different natural gas compositions along with different process parameters such as the amount of excess air. Thus, the required combustion temperature can be controlled by adjusting the natural gas composition or the combustion temperature can be specified based on the provided composition of the natural gas stream by using either the derived equations or output chart. (R1. 1). [ABSTRACT FROM AUTHOR]

In this article, the fractional third‐order dispersive partial differential equations were investigated by using Shehu decomposition and variational iteration transform methods. The well known Riemann‐Liouville fraction integral, Caputo's fractional‐order derivative, Shehu transform for fractional‐order derivatives and Mittag‐Leffler function were used as the major basis of the methodology. The graphs and table show the solution behavior for various fractional order values. The comparison provided the signed agreement of the solutions to each other as well as with the exact result. The accurateness and efficiency of the suggested techniques are examined using two numerical experiments. The reliability and validity tests show that for various fractional‐order values, the newly proposed method is reliable, accurate, and efficient. [ABSTRACT FROM AUTHOR]

Dryers are utilized in food industry and agriculture in order to extend the useful lifespan of corps. Thermal energy is required for water removal in the process of drying which can be provided by different sources. Solar thermal energy is one of the most applicable sources for drying processes with several benefits such as avoidance of greenhouse gas emission and availability. Regarding the involvement of various factors in the performance of solar dryers, this paper focuses on the works conducted on these systems. In this regard, various types of solar dryers including direct, indirect, mixed-mode and hybrid supplied by solar energy are discussed. According to the outcomes of this review paper, it can be determined that the performance of the solar dryers depends on various parameters such as the type of dryer, solar irradiation, drying time and operating condition. Moreover, it is found that there are several approaches applicable for improving the overall performance of the solar dryers such as utilizing thermal energy storage units, applying solar tracker and using modified materials. Furthermore, there is high potential for integrating the solar dryers with other systems to achieve higher efficiency and reliability. In addition to energy analysis and drying capacity, the solar dryers have been investigated more deeply by applying exergy analysis and the dependency of exergy efficiency on the operating factors are discussed. Environmental analysis conducted on solar dryers reveals high potential of these systems in carbon dioxide mitigation. In addition, the determined payback periods of these systems are acceptable in majority of the investigated cases which shows their advantage in term of economy. [ABSTRACT FROM AUTHOR]

Safe disposal of some hazardous substances requires incineration at elevated temperatures. High temperature incineration prevents the formation of another type of hazardous substance in gaseous phase. This work focuses on the utilization of the energy stored in the gaseous effluents from the rotary kiln incinerators when combusting the polychlorinated biphenyls (PCBs) hazardous wastes. The incineration process with a heat recovery unit and a steam power plant as one unit is simulated using MATHCAD software. Results show that by using two heat exchanger units, shell-and-tube and cross-flow heat exchanger, the overall efficiency of the steam power plant is improved by 10%. A significant fuel savings value is also reported. [ABSTRACT FROM AUTHOR]

Most of the available studies in literature focus on using photovoltaic systems to partially empower buildings. Solar energy can help in providing a certain amount of power to buildings. Full dependence on solar energy to provide daily demands to power of a building is not considered due to high cost. Thus in this research, the economic aspects of using a photovoltaic system to provide the full power for Kuwait residential buildings is investigated. The technical information for the solar system is assumed to have a full economical study; the technical information include information about load, panel array sizing, battery size, selection of controller and the selection of inverter. The economic analysis includes the estimation of payback period, return on investment (ROI), net present value (NPV), and cost of electricity consumption based on Ministry of Electricity and Water (MEW) tariffs in Kuwait. Weather conditions will be included in the selection of photovoltaic system components. It was found that the monocrystalline panel is the most suitable for the solar system. The tariff values have strong effect on the feasibility to use the photovoltaic system as the only source of power. Higher values of tariffs gives smaller payback period for example payback period calculated to be 7 years for 0.015 KWD (Kuwait Dinars) per kWh of the cost of electricity. Positive net present values are achieved for using photovoltaic cells to supply full power needs for a typical apartment in Kuwait. The problem of having large surface areas of solar cells is solved by using high efficiency solar cells. [ABSTRACT FROM AUTHOR]

In countries where wind energy is less feasible, an energy harvesting device such as highway wind turbines can still be used for applications where less power is needed. This energy can be harvested using vertical axis wind turbines (VAWT) placed on the sides of the highways to make use of the vehicles moving in both directions. This work presents an experimental study of using a three-bladed helical VAWT specially designed and manufactured for producing electrical energy from wind energy of moving cars on highways for lighting purposes such as the highway lights, traffic signals, and light guide lines. The wind speed of vehicles passing on a highway and wind power from the VAWT is measured at a number of anemometer heights on the highway sides. Results show that the VAWT prototype has produced up to 48-Watts of power from vehicles moving on the highway, which produce an average wind speed of 4.4 m/s. The wind turbine power curve is produced from the measured data and based on the best fit to the power curve, the efficiency of 34.6 percent is obtained, which is promising for further development of the work in commercial scale. [ABSTRACT FROM AUTHOR]

This paper shows a few novel calculations for wind speed estimation, which is focused around soft computing. The inputs of to the estimators are picked as the wind turbine power coefficient, rotational rate and blade pitch angle. Polynomial and radial basis function (RBF) are applied as the kernel function of Support Vector Regression (SVR) technique to estimate the wind speed in this study. Instead of minimizing the observed training error, SVR_poly and SVR_rbf attempt to minimize the generalization error bound so as to achieve generalized performance. The results are compared with the adaptive neuro-fuzzy (ANFIS) results. [ABSTRACT FROM AUTHOR]