Browsing by Author "Karim, Mounia"

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    Effect of operation time on the performance and accuracy of the Condor reflectometer
    (TIB Open Publishing, 2024-07-24) Karim, Mounia; Sansom, Christopher; Hussaini, Zaharaddeen; Almond, Heather; Fernández-García, Aránzazu; Sutter, Florian; Wiesinger, Florian; Wette, Johannes; King, Peter
    This paper evaluates the potential effect that operation lifetime could have on the accuracy and reproducibility of the Condor reflectometer. For this purpose, three Condors with different operation lifetimes have been used and compared in this study. In addition to the device’s operation lifetimes, reproducibility and the repeatability of the measurements have also been evaluated. Silvered glass mirrors at different states have been used, e.g., clean, soiled and eroded in order to evaluate the effect of the surface properties on the difference reported using different devices. The obtained results have shown that the difference in specular reflectance reported by the three different Condors is more noticeable in case of soiled and eroded glass mirrors compared to clean sample. This could be linked to the surface roughness more than to the years of operation of the device itself.
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    Impact of dust on electrical power output of solar PV modules in North-East, Nigeria
    (Niger State College of Education, 2022-05-30) Abdulkarim, Hauwa Talatu; Sansom, Christopher L.; Patchigolla, Kumar; Almond, Heather; Karim, Mounia
    The impact of dust on the solar PV modules deserves more attention. North-eastern Nigeria has high potential of solar irradiance but it is proned to dust accumulation. This paper therefore, investigated the impact of dust on the performance of solar Photovoltaic modules in North-Eastern Nigeria. The investigation entailed field experiment carried out in Maiduguri to assess the performance of the module based on continuous dust deposition for 14 days during dust accumulation period. The results show that more than 50% loss in power output was recorded under 14 days of continuous deposition. The efficiency of the module reduced from 17.1% on the first day to 7.2% on the fourteenth day of the experimentation. The investigation also shows that at high humidity the PV performance drops. Solar irradiance increases the performance. The deployment of solar PV energy supply system is recommended in spite of dust accumulation challenges. To maintain adequate performance of the system, a once a week cleaning is recommended during intense dust accumulation period.
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    Investigation of the Thermo-hydraulic performance of a roughened Parabolic trough collector
    (Elsevier, 2022-10-28) Allauddin, Usman; Rafique, Muhammad U.; Malik, Osama; Rashid, Osama; Waseem, Ashir; King, Peter; Karim, Mounia; Almond, Heather
    Parabolic trough collectors (PTC) are an already established technology set to prove its competitiveness. Recently, a lot of research is ongoing to further enhance the thermal performance of PTC systems. Computational Fluid Dynamics (CFD) can help in the design and development of PTCs with optimized thermal efficiency. In the current work, a combined enhancement in the performance of a PTC is evaluated, involving modifications to the geometry of the absorber tube and the use of a heat transfer fluid (HTF) (Syltherm800). Absorber tube geometries involving dimpled protrusions (d-PTC) and circumferential inclined ribs (IR-PTC) are used. The performance of PTC with and without turbulators is compared with that of a smooth absorber tube by calculating the Nusselt number (Nu), friction factor (f) and performance evaluation criterion (PEC). PEC values of 1.46 and 1.18 are observed by using inclined ribs and dimpled protrusions, respectively at an absorber tube inlet temperature (Tin) of 500 K and mass flow rate (m) of 0.5 kg s−1. Thus, a significant enhancement in thermo-hydraulic performance of PTC is observed with inclined rib turbulators.
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    Numerical simulation of subfields in a multi-tower concentrated solar field
    (TIB Open Publishing, 2024-07-24) Hussaini, Zaharaddeen Ali; Sansom, Chris; King, Peter; Karim, Mounia
    The research introduces an innovative approach to enhancing the efficiency of Multi-tower Concentrated Solar Power (CSP) through a configuration termed Auxiliary Tower with Subfield (ATS). ATS introduces an auxiliary tower and creates a subfield by adding heliostats near its position, aiming to optimize the solar field's optical efficiency and offer modular decentralized power output. ATS configuration employs existing field configurations to pinpoint inefficiencies where an additional tower can be installed, and heliostats are systematically added to the subfields through numerical optimization using various design variables. Although the inclusion of a subfield in the ATS configuration enhances energy output, it does not always offset the additional costs of the auxiliary tower, receiver, and extra heliostats, in small fields. However, when applied to larger fields, starting from 200MWth, ATS begins to provide a lower Levelized Cost of Heat (LCOH) compared to optimized conventional thermal fields, demonstrating its potential applicability and efficiency in larger-scale CSP setups. Applying ATS to a 120 MWth Gemasolar-like plant further confirms its advantages, with 160 MWth emerging as the optimal enhancement point that boosted efficiency while lowering LCOH. ATS shows promise as an efficient, modular approach to scaling up power tower system.
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    Variability and associated uncertainty in image analysis for soiling characterization in solar energy systems
    (Elsevier, 2023-07-04) Smestad, Greg P.; Anderson, Cody; Cholette, Michael E.; Fuke, Pavan; Hachicha, Ahmed Amine; Kottantharayil, Anil; Ilse, Klemens; Karim, Mounia; Khan, Muhammad Zahid; Merkle, Herbert; Miller, David C.; Newkirk, Jimmy M.; Picotti, Giovanni; Wiesinger, Florian; Willers, Guido; Micheli, Leonardo
    The accumulation of soiling on photovoltaic modules and on the mirrors of concentrating solar power systems causes non-negligible energy losses with economic consequences. These challenges can be mitigated, or even prevented, through appropriate actions if the magnitude of soiling is known. Particle counting analysis is a common procedure to characterize soiling, as it can be easily performed on micrographs of glass coupons or solar devices that have been exposed to the environment. Particle counting does not, however, yield invariant results across institutions. The particle size distribution analysis is affected by the operator of the image analysis software and the methodology utilized. The results of a round-robin study are presented in this work to explore and elucidate the uncertainty related to particle counting and its effect on the characterization of the soiling of glass surfaces used in solar energy conversion systems. An international group of soiling experts analysed the same 8 micrographs using the same open-source ImageJ software package. The variation in the particle analyses results were investigated to identify specimen characteristics with the lowest coefficient of variation (CV) and the least uncertainty among the various operators. The mean particle diameter showed the lowest CV among the investigated characteristics, whereas the number of particles exhibited the largest CV. Additional parameters, such as the fractional area coverage by particles and parameters related to the distribution's shape yielded intermediate CV values. These results can provide insights on the magnitude inter-lab variability and uncertainty for optical and microscope-based soiling monitoring and characterization.