Renewable Energy Research and Applications
Volume:1 Issue: 2, Summer-Autumn 2020

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.

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.

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.

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

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.

A case study is conducted to evaluate the photovoltaic (PV) performance in a horizontal and in an inclined PV solar thermal collector (PVT) for two different PVT geometries; the series flow and the parallel series flow. It is shown that the series flow gives a better photovoltaic performance at a horizontal PVT surface as compared to the parallel series flow. At mass flow rate of 0.03 kg/s and zero inclination angle (horizontal PVT surface), the PV efficiencies are 14.32 % and 14.25 % for series and parallel series flow, respectively. But for an inclined PVT surface, the parallel series performs better than that of the series flow. At mass flow rate of 0.03 kg/s and inclination angle of 45 °C, the PV efficiencies are 13.76 % and 13.87 % for series and parallel series flow, respectively. It can be concluded that the inclination angle is one of the essential parameters that can be used to evaluate any PVT design and make better comparison between different designs. It is also beneficial for researchers and PVT product designers to know the effectiveness of their collector designs for cooling the PV panel at the early product design stage and to base on the optimum inclination angle of the region.

Exergy analysis of a 250 MW power plant is done in this study. Thermal performance analysis using MATLAB calculation tool has been done. Exergy destruction phenomenon and Exergetic efficiency is calculated for various components of 250 MW coal fired subcritical power plant. The calculated overall plant exergy efficiency is evaluated 34.75%. Besides, results also concluded that exergy destruction takes place in the steam generator 490.76 MW (93.07%) followed by the other components. The comparative study of heat loss ratio with respect to varying plant load is performed out of which condenser contribute to have major heat loss ratio. The outcomes of this research study will be beneficial for future researchers.

The purpose of this research is to supply the electricity required by renewable energies used by the photovoltaic cell, in this regard, have been using the type of crystal silicon photovoltaic cells. The used software with this regard is Homer. Homer is capable of simulating renewable energies to monitor demand for loads. Electricity is generated by the Pv cell, but the energy produced in DC. While the energy required is alternating after the voltage converter is used for conversion. The storage will be used at times when there is no electricity produced by the PV cell or the production of electricity is higher than the demand, in this study the battery is considered a storage unit. The important results of this study can be attributed to the production of 15339 kW electricity by the Pv cell.

This paper aims to determine the optimal performance characteristics of a solar tracking system in order to maximize the power generation through using the MOPSO algorithm. Considering the sun path during a day, the necessity of using solar tracking systems to achieve the maximum power output from photovoltaic (PV) panels has been investigated. The solar tracking system allows PV arrays to follow sunlight all day long. The unidirectional tracking system follows the sun path, thereby optimizing the angular motion of PV arrays relative to the sun resulting in higher power generation. To evaluate the performance of a PV system, the total solar radiation was calculated first for both fixed and unidirectional tracking systems. Analyzing the results indicates that for June 20th the power generation of the PV module equipped with a unidirectional tracker is 35% higher than the fixed PV module. The optimal value of the declination angle, Azimuth, and arrays’ tilting angles in a unidirectional tracking system calculated using the MOPSO algorithm are , and respectively.

In this paper, a novel thermal driven supercharging system for downsizing of a turbocharged diesel engine is proposed. Furthermore, Kalina cycle has been used as waste heat recovery system to run the mounted supercharging system. The waste heat of air in engine exhaust and intake pipes is converted to cooling and mechanical power by Kalina cycle. The mechanical power produced by Kalina cycle is transferred to an air compressor to charge extra air to the engine for generating more power. This feature can be used for downsizing the turbo-charged heavy duty diesel engine. In addition, the heat rejected from engine intercooler is transferred to Kalina cycle vapor generator component, and part of engine exhaust waste heat is also used for superheating Kalina working fluid before entering engine. Then, first and second law analysis are performed to assess the operation of the engine in different conditions. Moreover, an economic model is provided for the Kalina cycle which is added to engine as supplementary component. Finally, simple payback and Net present value methods are used for economic evaluation of the added supplementary system. According to the results, mounting the novel waste heat driven air charging system has resulted in increment of air mass flow rate which leads to extra power generation (between 9 kW and 25 kW). The payback period and profitability index of the project are approximately 3.81 year and 1.26, consecutively.

Finding a superior evaluation for an irreversible actual heat engine (irreversible Carnot heat engine) can be mentioned as the substantial purpose of this study. To obtain this purpose, the considered criteria are Ecological Coefficient of Performance (ECOP), exergetic performance coefficient thermo-economic, ecological-based thermo-economic, and ecologico-economical functions. These criteria are optimized by implementing NSGA II and thermodynamic analysis. Irreversibilities of the system is considered for the study assessment, consequently, two states are specified in the optimization procedure. The findings associated with every scheme are assessed independently. In the first scenario, maximizing the power output, First law efficiency of the system, and dimensionless ecological-based thermo-economic function ( ) is set as the target. In the second scenario, the three objective functions such as power output ( ), efficiency ( ) and dimensionless ecologico-economical ( ) are simultaneously maximized. To be clear, the coupled of multi-objective evolutionary approaches (MOEAs) and non-dominated sorting genetic algorithm (NSGA-II) approach are presented. The comparison of three prominent approaches such as: LINAMP, TOPSIS, and FUZZY performs in decision making. Ultimately, error analyses of results based on Maximum Absolute Percentage Error are carried out. According to the results, in the first scenario, the appropriate results were the result of the decisions made by TOPSIS and LINAMP, with a deviation index equal to 0.322 from the ideal ratio of this scenario. In the second scenario, the best decision-making results were achieved by the TOPSIS method, with a deviation index equal to 0.104 from the ideal state for this scenario.

Wind energy is considered as a precious replacement for fossil fuels in electricity generation. In this regard, many governments (e.g. Iran) tend to support development of this type of renewable energy source. However, fluctuations in Iran’s economic conditions and uncertainty in available wind power increase the risk of investment. In this investigation a methodology is used to address the uncertainty in wind conditions using probability of occurrence of minimum wind speed. In addition, a feasibility study is considered for economic assessment of establishing a wind turbine power plant in Kerman province, Iran. A sensitivity analysis is developed to analyze the effect of changes in inflation and currency rates on the project economic viability. Results show that the proposed site enjoys excellent wind power potential with respect to wind power density of 971.4 W/m2 at 100 meters height. Economic analysis indicates that the project is viable when its budget is supplied through governmental resources (providing US dollar at governmental rate). However, sensitivity analysis reveals that the project is no longer viable when its budget is supplied through foreign exchange market (providing US dollar at market currency rate). Therefore, this paper suggests that if government tends to support development of wind energy in Iran, it is necessary to either provide the project budget by governmental resources (4200 T/$) or buy electricity higher than 1391.6 T/kWh (845.6 T/kWh more than current feed-in-tariff). Furthermore, nonlinear relationship between net present value (NPV) and inflation shows that reduction in inflation can significantly improve the investment payoff.