فهرست مطالب

  • Volume:1 Issue: 2, 2020
  • تاریخ انتشار: 1398/12/14
  • تعداد عناوین: 5
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  • A. Ahmadi *, M. A. Ehyaei Pages 135-141
    Entropy generation can be caused by the energy transfer from a high-temperature recourse to a low-temperature resource; this is defined by the second law of thermodynamics. This phenomenon can occur for the Earth by transferring the solar energy from the sun to the earth. The process of entropy generation of the Earth is an important concept for the life of the earth. This process also has significant effects on the global hydrological cycle, carbon cycle of the Earth’s atmosphere, and global warming. This paper presents an approximate method to estimate the entropy generation of the earth caused by the sun. Application of the heat engine to calculate the entropy generation of the planets has been carried out so far. In this research work, the concept of heat engine is applied to calculate the entropy generation of the earth and the atmosphere surrounding it in a relatively simple model. Based upon this calculation, the rate of entropy generation of the earth and its surrounding atmosphere is . Moreover, by considering this imaginative heat engine, the first and second law efficiencies are equal to 0.11036 % and 0.11546 %, respectively. The results of this research work have also been justified by similar works on this topic.
    Keywords: Entropy, Earth, Atmosphere, Thermodynamic, First Law Efficiency, Second Law Efficiency
  • E. Bani Hani *, F. Alkhatib, A. Sedaghat, A Alkhazzam, F. Al Dousari, O. Al Saad Pages 143-150

    Used engine oil is one of the most environment pollutants that is produced in large quantities. Methods of recycling and reuse of the oil are important for sustainable environment. In this work, a new experimental method is proposed for producing diesel-like fuel from the waste engine oil. The study proposes new physical and chemical treatment methods to produce diesel-like fuel from the used engine oil. The produced oil is chemically analyzed to characterize the produced engine oil fuel for application in a diesel engine, to calculate the power produced, to measure the gaseous emissions and to compare with the standard diesel fuel. The diesel-like fuel properties are investigated including viscosity, flash point, pour point, energy content, and gaseous emissions. The diesel-like fuel proves to emit less gaseous pollutants such as NOx than the diesel fuel. The diesel-like fuel is tested in a diesel engine which provided the efficiency of 22.4%. The proposed experimental approach proves sustainable for producing diesel-like fuel from waste engine oils and protects the environment from the abundant amount of the waste engine oil.

    Keywords: air pollution, Engine oil, Environmental management, Fuel, Waste
  • H. Berahmandpour *, Sh. Kouhsari, H. Rastegar Pages 151-160

    Economic dispatch in the presence of wind farms is of high interest in power system operational planning. Due to the uncertainty of wind speed and wind power, a probabilistic model is needed for application in economic dispatch solution. The weibull probability distribution function is a common tool to model wind speed probabilistic behavior, but the main challenge is the nonlinearity of wind power generation with respect to wind speed. This causes complexity in probabilistic economic dispatch, which can lead to numerical and time-consuming solution methods. Therefore, linearization of the wind power curve is in the interest of some methods by simply connecting the first point to end point of power curve by a straight line. In this paper, by developing a conventional objective function for ED solution, two main contributions are made to obtain a suitable method for fast and also good accuracy results in real time purposes. At first, an improved method for linearization of wind power curve with respect to previous works is introduced which increases the performance of modelling with respect to the nonlinear model as the base model. The second contribution is developing an analytical routine for economic dispatch by an acceptable time-consuming calculation suitable for real time purposes. The effectiveness of the new approach has been tested on two test systems. The results show the improvement in relative error in ED cost with respect to real nonlinear curve model which reduces the error about one fifth regard to the conventional linearization model.

    Keywords: Wind power. Economic dispatch, Real time simulation, Weibull probability function, Linearization
  • N.O. Adeniji *, J.O. Adeniji, O. Ojeikere Pages 161-174
    Global solar radiation is the sum total of all radiation reaching the earth surface i.e. it includes: the direct and the diffused solar radiation reaching the earth surface. The instrument used for measuring this very important component arriving from the whole hemisphere is the pyranometer. This is one of the most important parameter for applications, developments and researches related to alternative source of clean and renewable energy. In cases where these data are not available, it is very common to use computational models to estimate the missing data, which are based mainly on the search for relationships between weather variables, such as temperature, humidity, precipitation, cloud cover and sunshine hours, among others. In this research work, the baseline data for mean monthly global solar radiation and sunshine hours for three (3) geopolitical zones of Nigeria (sub-sahara regions of Nigeria) with Sokoto (North-western Nigeria) (12.910N, 5.200E), Maiduguri (North-eastern Nigeria) (11.850N, 13.080E) and Ilorin (North- Central Nigeria) (8.430N, 4.500E) were obtained from the Nigeria Metrological Agency (NIMET), Nigeria which spread from 1996 to 2010. A linear regression correlation model was developed and clearness index estimated for each station in this study. The result shows the Angstrom coefficients and for estimating global solar radiation for zone respectively, using the Angstrom-Prescott model. The average global solar radiation for these stations was estimated, results subjected to statistical tests proven to be good estimates. The study concluded that the Angstrom- Prescott model plays a significant role in predicting and estimating solar energy potentials in these regions
    Keywords: Global solar radiation, Angstrom-Prescott model, Sunshine Hour, Clearness Index, Northern Nigeria
  • A. Naseri, M. Fazlikhani, M. Sadeghzadeh *, A. Naeimi, M. Bidi, Seyyed H. Tabatabaei Pages 175-185

    In this paper, a novel CO2 transcritical power cycle which is driven by solar energy integrated by a cryogenic LNG recovery unit is investigated. In the proposed cycle, the condenser unit of the CO2 power cycle is replaced by a Stirling engine. Thermodynamic and exergy analyses are carried out to evaluate the performance of the presented system. Furthermore, in order to investigate the impact of utilization of Stirling engines instead of conventional condenser units, the proposed cycle is compared with the typical CO2 power cycle. The results show that employing the Stirling engine decrease the exergy destruction from 17% in the typical cycle to 8.85%. In addition, the total generated power of the novel system is considerably boosted up about 15 kW in off-peak times and more than 20 kW in the peak time. Moreover, integration of the Stirling engine also decreases LNG mass flow rate. Therefore, the required heat exchanger area in the LNG heater is also lowered.

    Keywords: Solar collector, transcritical CO2 power cycle, LNG, Stirling engine, exergy