The need to capture the maximum amount of solar energy and to optimize the panels’ collecting surfaces are among the primary objectives of research in solar engineering. The simplest way to accomplish this is to perform a monthly accurate determination of the solar collector’s proper slope and azimuth angles. Indeed, this is the aim of this article, which consists of a graphical optimization based on the Gueymard’s daily integration model. A Matlab program was developed to predict the hourly solar radiation on a solar receiver using the Gueymard model in conjunction with the Liu and Jordan isotropic, Perez, and HDKR anisotropic models. A comprehensive simulation of the monthly solar irradiation throughout 2018 was executed for the city of Annaba, in north–eastern Algeria. The results indicate that the south-facing surface azimuth angle is the most appropriate. In fact, for maximum sunlight capture, the solar collector inclination must be adjusted each month in the range of [10–40°]. Furthermore, the results show that the gains in the amount of solar radiation received throughout the year by the thermal panel mounted at monthly optimum tilt angles are 15.63% in January and 7.37% in July.
The transversal aspect ratio of solar air heaters (SAHs) is a critical geometric parameter that influences the heat transfer from the absorber plate to the working fluid and, accordingly, the overall heat loss level. The present work addresses the effect of the aspect ratio on the performance of a solar air heating system and the behavior of heat transfer coefficients (HTCs) within it and along the flow channel. A mathematical model of energy‐balance equations was formulated to examine and analyze the double‐glazed solar air heater thermal behavior. The Eismann correlation, which is more accurate than Holland's correlation, was employed to determine the HTC between the two glass covers. The useful energy, Nusselt number (Nu), efficiency, overall loss, and HTCs as a function of the aspect ratio were evaluated across the collector length. On the basis of the findings, the higher the ratio, the better the efficiency of the SAH. Indeed, increasing the collector's cross‐sectional aspect ratio (r) up to 19 increases useful energy efficiency by more than 87%, Nu by 84%, thermohydraulic efficiency from 0.4 to 0.76, and overall heat loss by 1.15 W/(m2 K). Furthermore, reducing r from 19 to 2 will improve the collector power from 1.855 to 3.473 kW.
The gas turbines (GTs), model M3142R/GE MS 3002, equipping the natural gas compression and crude oil pumping stations of SONATRACH’s pipeline transport of hydrocarbons activity are robust despite their dilapidation and state of service, but mediocre in terms of energy efficiency and power output. According to the manufacturer, for temperatures ranging from 15 to 47 °C, the efficiency of these machines drops from 26.78 to 25.03 % and their power drops from 11.29 to 8.9191 MW. It should be noted, however, that the number of these turbines exceeds 80 units and that their operation dates from 1974. The intention of this paper is to improve the gas turbine performance, mainly the efficiency and shaft power, by an evaporative cooling process of the compressor intake air. Besides, it is proposed to lower the upper limit power in periods of high temperatures to reduce gas consumption. To achieve these objectives, a mathematical model was implemented under Matlab R16, which reproduced the real behavior of these machines. It follows that this simulation made it possible to highlight relevant gains in terms of power and efficiency of the order of 1.361 MW and 3.4 % at a temperature of 47 °C.
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