Aerosol-induced losses in the solar potential

The atmospheric aerosol loading may significantly influence the performance in solar power production. The impact can be very different both in space (even in short distance) and time (shortterm fluctuations as well as long-term trend). Aiming to ensure a high degree of generality, this study is focused on the aerosol impact on the collectable solar energy. Thus, the results are independent of solar plants characteristics. A new methodology for estimating the average daily,monthly, and yearly losses in the solar potential due to aerosols is proposed. For highlighting the loss in the overall solar potential, a new ideal scenario is defined as a reference for the atmospheric aerosol background. A new equation for computing the solar potential loss is proposed to adjust for possible biases. In a departure from similar studies, the analysis relies on ground measurements (BSRN and AERONET), always more accurate than remotely sensed satellite data. The seldom discussed impact of aerosol type is considered. As a general conclusion, the monthly and yearly reductions of the solar potential due to aerosols are estimated at 12 locations spread around the globe, amounting to losses of the solar potential ranging from 0.6% to as high as 7.2%

Thermodynamic study of atmospheric corrosion seasonal kinetic, based on Sun photometer data

Zbog ogromnih gubitaka koji nastaju na strojarskim materijalima, atmosferska korozija predstavlja tehnološki, ekonomski, kao i ekološki problem zbog povećanja sadržaja onečišćenja u životnom okolišu. U ovom radu su prikazani rezultati termodinamičke dijagnostike ograničavajućeg stupnja ukupne kinetike korozije uslijed dodira čvrstih površina s vodenom parom, na osnovu podataka dobivenih svakodnevnim promatranjem tlaka vodene pare u Temišvaru 2011., od ožujka do prosinca. Na osnovu sezonskih vrijednosti izračunate su konstante difuzije vodene pare, nastale uslijed gradijenta koncentracije, kao i energije termokemijske aktivacije prvog stupnja korozije, na osnovu Ahrrenijusove jednadžbe. Izračunate relativne sezonske varijacije kemijske polarizacije vodene pare u odnosu na ukupnu promjenu entropije nastale i kondenzacijom na čvrstim površinama, uspoređene su s literaturnim vrijednostima za slobodne Gibbs-energije mogućih produkata relaksacijskih termokemijskih reakcija. Ograničavajući stupanj ukupnog procesa korozije, određen je usporedbom molarnog rada depolarizacije sukcesivnih elektrokemijskih relaksacijskih procesa. Depolarizacijski rad proporcionalan je konstanti brzine sezonski aktiviranih sukcesivnih relaksacijskih procesa u razdoblju koncentracijske depolarizacije vodene pare: elektrokemijske relaksacije kisika i vodika pri pretlaku depolarizacije vodika i standardnom potencijalu indikatora anodnog rastvaranja metala. Podaci rabljeni za izračunavanje tlaka vodene pare u atmosferi dobiveni su pomoću fotometra iz meteorološke stanice na "Politihnici" Sveučilišta u Temišvaru, Rumunjska (45,74 °N; 21,22 °E). Mjerenja su provedena u području valnih duljina 940 nm, uporabom empirijskih modela i podataka o temperaturi, barometarskom tlaku i vlažnosti zraka, a suglasne su s rezultatima 4 različite metode s varijacijama do 2 %.The atmospheric corrosion is a mechanical, technological, economic as well as an ecological problem, due to the enormous losses in corroded vessels material and machine material due to enhanced content of corroded material pollutants in environment. The results of the thermodynamic diagnostic study are given in this paper of the limited step in the water vapor corrosion kinetic based on the monitoring data for the seasonal water vapor pressure measured daily in Timisoara, by 2011, from March to December. Based on the seasonal values of the measured data, the seasonal diffusion rate constants the activation energies of the first chemical corrosion step are determined. The calculated seasonal water vapor chemical surface polarizations relative to the values of equilibrium entropies and also of the condensed water vapor on the solid surfaces are compared with the literature data of the possible products of chemical processes. The thermodynamic diagnostic study of the limited successive relaxation step in overall corrosion kinetic is carried out, based on the comparison of the molar water vapor couple relaxation work. The depolarization work is proportional to the depolarization rate constants of reactants and products activated successively in couple with water vapor concentrations depolarization energy, in the same time period: the electrochemical relaxation for the achievement of oxygen and hydrogen equilibrium in the seasonal activated corrosion cell, hydrogen depolarization energy and oxygen striping indicators standard potential. Data used to calculate the water vapor pressure in atmosphere are based on measurements accomplished by a sun photometer located at the Politechnica University of Timisoara, Romania (45,74 °N; 21,22 °E). The extraction of water vapor amount from sun photometer capacity relies on a measurement in the region of water vapor absorption at 940 nm. In order to apply the empirical models, the temperature, barometric pressure and humidity content have been taken from a weather station. One found that the experimental values of water vapor pressure, obtained using the sun photometer, are comparable with four other methods, and within, the experimental variations is characterized by a relative error of 2 %

Thermodynamic study of atmospheric corrosion seasonal kinetic, based on Sun photometer data

Zbog ogromnih gubitaka koji nastaju na strojarskim materijalima, atmosferska korozija predstavlja tehnološki, ekonomski, kao i ekološki problem zbog povećanja sadržaja onečišćenja u životnom okolišu. U ovom radu su prikazani rezultati termodinamičke dijagnostike ograničavajućeg stupnja ukupne kinetike korozije uslijed dodira čvrstih površina s vodenom parom, na osnovu podataka dobivenih svakodnevnim promatranjem tlaka vodene pare u Temišvaru 2011., od ožujka do prosinca. Na osnovu sezonskih vrijednosti izračunate su konstante difuzije vodene pare, nastale uslijed gradijenta koncentracije, kao i energije termokemijske aktivacije prvog stupnja korozije, na osnovu Ahrrenijusove jednadžbe. Izračunate relativne sezonske varijacije kemijske polarizacije vodene pare u odnosu na ukupnu promjenu entropije nastale i kondenzacijom na čvrstim površinama, uspoređene su s literaturnim vrijednostima za slobodne Gibbs-energije mogućih produkata relaksacijskih termokemijskih reakcija. Ograničavajući stupanj ukupnog procesa korozije, određen je usporedbom molarnog rada depolarizacije sukcesivnih elektrokemijskih relaksacijskih procesa. Depolarizacijski rad proporcionalan je konstanti brzine sezonski aktiviranih sukcesivnih relaksacijskih procesa u razdoblju koncentracijske depolarizacije vodene pare: elektrokemijske relaksacije kisika i vodika pri pretlaku depolarizacije vodika i standardnom potencijalu indikatora anodnog rastvaranja metala. Podaci rabljeni za izračunavanje tlaka vodene pare u atmosferi dobiveni su pomoću fotometra iz meteorološke stanice na "Politihnici" Sveučilišta u Temišvaru, Rumunjska (45,74 °N; 21,22 °E). Mjerenja su provedena u području valnih duljina 940 nm, uporabom empirijskih modela i podataka o temperaturi, barometarskom tlaku i vlažnosti zraka, a suglasne su s rezultatima 4 različite metode s varijacijama do 2 %.The atmospheric corrosion is a mechanical, technological, economic as well as an ecological problem, due to the enormous losses in corroded vessels material and machine material due to enhanced content of corroded material pollutants in environment. The results of the thermodynamic diagnostic study are given in this paper of the limited step in the water vapor corrosion kinetic based on the monitoring data for the seasonal water vapor pressure measured daily in Timisoara, by 2011, from March to December. Based on the seasonal values of the measured data, the seasonal diffusion rate constants the activation energies of the first chemical corrosion step are determined. The calculated seasonal water vapor chemical surface polarizations relative to the values of equilibrium entropies and also of the condensed water vapor on the solid surfaces are compared with the literature data of the possible products of chemical processes. The thermodynamic diagnostic study of the limited successive relaxation step in overall corrosion kinetic is carried out, based on the comparison of the molar water vapor couple relaxation work. The depolarization work is proportional to the depolarization rate constants of reactants and products activated successively in couple with water vapor concentrations depolarization energy, in the same time period: the electrochemical relaxation for the achievement of oxygen and hydrogen equilibrium in the seasonal activated corrosion cell, hydrogen depolarization energy and oxygen striping indicators standard potential. Data used to calculate the water vapor pressure in atmosphere are based on measurements accomplished by a sun photometer located at the Politechnica University of Timisoara, Romania (45,74 °N; 21,22 °E). The extraction of water vapor amount from sun photometer capacity relies on a measurement in the region of water vapor absorption at 940 nm. In order to apply the empirical models, the temperature, barometric pressure and humidity content have been taken from a weather station. One found that the experimental values of water vapor pressure, obtained using the sun photometer, are comparable with four other methods, and within, the experimental variations is characterized by a relative error of 2 %

Impact of Aerosol on the Estimation Accuracy of Solar Radiation

The paper is focused on the solar irradiance estimation in clear-sky conditions and an aerosol-loaded atmosphere. Two parametric models developed by our group and three empirical models are tested. The estimates of the parametric models are based on three atmospheric parameters (ozone, nitrogen dioxide and water vapor column content) and the aerosol properties quantified by means of several specific parameters (Ångström turbidity coefficient, single scattering albedo, asymmetry factor). The empirical models contain no inputs for aerosol properties. Data collected from 10 stations were used to test the models. The inputs for the parametric models were retrieved from Aerosol Robotic Network - AERONET. Global and diffuse solar irradiance data at high-quality standards were retrieved from the Baseline Surface Radiation Network BSRN. A comparative analysis of the models’ accuracy in estimating clear-sky solar irradiance is discussed from the perspective of aerosol proprieties