The photovoltaic (PV) panels are expected to be the most important systems to meet global energy demand by converting solar energy into electricity. The main obstacle to the widespread deployment of the PV systems its the limited efficiency, which are greatly affected by the solar radiation and the operating temperature. The full knowledge of the performance, efficiency and output power of photovoltaic modules and the extent of their change with the fluctuations of solar radiation and temperature is necessary to determine the optimal size of the system and avoid the financial risks of the project. This paper investigated numaricaly and experimentaly the influence of operating temperature and solar radiation on the output power and efficiency of polycrystalline PV panels in Baghdad-Iraq. The PVsyst software was used to simulate a model implementing simulation results presented the impact of variations temperature and solar radiation in the curves of I-V, P-V and efficiency. In order to verify the reliability of the simulated results with experimental ones, several measuring devices have been used to conduct field experiments in the outdoor conditions. It were used to determine the characteristics and performance of a 120W polycrystalline PV panel for different ranges of solar radiation and operating temperature. The simulation results showed that the current, voltage, output power and efficiency increased with increasing solar radiation, while they decreased with increasing temperature except the current that was increased. The experimental and simulated results were identical in terms of the effect of temperature and solar radiation on the current, voltage, output power and efficiency of the PV panel. The experimental tests showed that when the temperature is increased by 1°C, the current was increased by about 0.068%, the voltage decreased by 0.34%, the output power decreased by 0.489% and the efficiency decreased about 0.586%. The experimental results displayed that the parameters of the PV panel under real operating conditions behave differently than in the standard test conditions (STC), as they are strongly affected by weather fluctuations in terms of temperature and solar radiation

Recently, most of the researchers focused on provide lower greenhouse gas emissions that emitted from diesel engines by using renewable fuels to be good alternative to the conventional diesel fuel. Ethanol can be derived from renewable sources such as sugar cane, corn, timber and dates. In the current study, the ethanol fuel used in the tests was derived from the dates. The effects of using exhaust gas recirculation (EGR) diesel-ethanol blend (E10) with on engine performance and emissions characteristics have been studied in diesel engine under various engine loads. This study focused the use of oxygen in the bio-ethanol composition to compensate for the decrease occurred by the addition of EGR, which improves the engine performance and reduces its emissions. In this experiment, the ratios of EGR were 10%, 20% and 30% as well as 10% ratio of ethanol was blended into the diesel fuel blend under fixed engine speed. A traditional (without additional systems to reduce emissions) four cylinders direct injection (DI) diesel engine was used for all tests. The brake specific fuel consumption (BSFC) increased with increasing the EGR ratio by 10%, 20% and 30% by 18.7%, 22.4% and 37.4%, respectively. The thermal efficiency decreased under variable conditions of engine load for different ethanol blends. Furthermore, the emissions of NOX decreased when fuelled B10 into the engine in comparison with diesel under low engine load. Significant reduction in the NOx emissions were found when applied EGR in the tests than to the absence EGR for E10 blend and diesel. The NOx reduction rate was 12.3%, 30.6% and 43.4% when EGR rate was 10%, 20% and 30%, respectively. In addition, the concentrations of HC and CO emissions decreased more by 8.23% and 6.4%, respectively, when using E10 in comparison with the diesel for various engine loads. It is indicated that the oxygen reduction by EGR effect was compensated from ethanol blend combustion. The results showed that the combination use of E10 and EGR leads to significant reduction in engine emissions accompanied with partial reduction in the engine performance.

In this study, data of the monthly average of daily global solar radiation falling on a horizontal surface, relative humidity, maximum temperature, and duration of sunshine for the city of Baghdad were collected through two sources. First, from the Iraqi Meteorological Authority (IMA) for a period extending from 1961 to 2016. The second is from NASA, for the period from 1984 to 2004. Then, four linear regression models, two single and two polynomials were formulated to calculate the values of the monthly average of daily global horizontal solar radiation (GHSR) incidents. The models calculated the monthly average of daily extraterrestrial radiation and day length, using some data provided by NASA and the IMA. To ensure the validity of the used models, a statistical test was performed for the performance of the proposed models, using the indicators mean bias Error (MBE), root mean square error (RMSE) as well as mean percentage error (MPE). The validation shows the relationship between the measured and computed values (through the analysis of the results), where a great convergence was found between the measured and calculated values. This means that the proposed models can be adapted to predict global solar radiation. The highest values of measured solar radiation were during the month of June, which were 28.555 and 27.280 MJ/m2/day from the IMA and NASA, respectively. The same applies to the radiation calculated using the four empirical models. The month of June was the highest in terms of solar radiation values. The radiation values were 28.947, 26.315, 29.699, and 26.716 MJ/m2/day for the first, second, third, and fourth models, respectively. The lowest values of measured and calculated radiation were during the month of December. Always, radiation measured by the IMA was greater than those of NASA, as well as the values of radiation calculated in the two IMA-based models were greater than the other two NSA-based models. In the absence of a method for measuring the diffuse and direct (beam) solar radiations, as well as the lack of such values by meteorological authorities, and its paramount importance, they were reported to mathematically calculate them in this study. The values of statistical indicators RMSE; MJ/m2/day, MBE; MJ/m2/day and MPE% were (0.4769, 0.0164, 0.2207), (0.8641, 0.1773, -0.9680), (0.6420, 0.3996, -1.1487), (0.9604, 0.218, -1.0225) for the first, second, third and fourth models, respectively. According to the results of the statistical test, it can be indicated that the single linear regression model, based on the IMA’s data (model No.1), is the most accurate to calculate global solar radiation for Baghdad City.