An optimum location of on-grid bifacial based photovoltaic system in Iraq

Bifacial photovoltaic (PV) module can gain 30% more energy compared to monofacial if a suitable location were chosen. Iraq (a Middle East country) has a variable irradiation level according to its geographic coordinates, thus, the performance of PV systems differs. This paper an array (17 series, 13 parallel) was chosen to produce 100 kWp for an on-grid PV system. It investigates the PV system in three cities in Iraq (Mosul, Baghdad, and Basrah). Effect of albedo factor, high and pitch of the bifacial module on energy yield have been studied using PVsyst (software). It has been found that the effect is less for a pitch greater than 6 m. The energy gained from bifacial and monofacial PV system module in these cities shows that Mosul is the most suitable for installing both PV systems followed by Baghdad and lastly Basrah. However, in Basrah, the bifacial gain is 12% higher in the energy than monofacial as irradiation there is higher than the other locations, especially for elevation above 1.5 m. Moreover, the cost of bifacial array is 7.23% higher than monofacial, but this additional cost is acceptable since the bifacial gain is about 11.3% higher energy compared to the monofacial.

NUMERICAL INVESTIGATION OF A SOLAR-DRIVEN ORGANIC RANKINE CYCLE COUPLED TO A GEOTHERMAL FIELD

The objective of this work is to investigate a solar-driven Organic Rankine Cycle (ORC) for power production with a geothermal well as the heat sink for the ORC condenser. The examined unit combines the exploitation of two renewable energy sources. Solar irradiation is exploited by using solar dish concentrators with spiral absorbers, while the geothermal field includes vertical boreholes with U-tubes. The system is investigated parametrically with a developed model in Engineering Equation Solver, and the examined parameters are the solar beam irradiation level, the total thermal conductivity of the ORC condenser, the borehole length, the number of the boreholes and the mean ground temperature. For the default scenario, it is found that system electrical efficiency is 21.45%, the ORC’s thermodynamic efficiency is 35.99%, and the solar field efficiency is 61.30%. Moreover, it is found that the examined system is 5.7% more efficient than a conventional air-cooled condenser system.

DESIGN OF MAXIMUM POWER POINT TRACKER CONTROLLER FOR BOOST CONVERTER PHOTOVOLTAIC ARRAY SYSTEM BASED ON FUZZY MAMDANI LOGIC

This paper discusses the analysis for a proposed design of a maximum power point tracker (MPPT) controller for a photovoltaic (PV) array solar system. Deploying a fuzzy Mamdani logic to track the maximum- power for the PV system when the atmospheric conditions are changed. The fuzzy Mamdani logic controller techniques have high efficiency, rapid response to new environmental factors, and are unaffected by circuit parameter changes. This controller able to adjust the duty cycle fed switching circuit of DC/DC boost to increase the output voltage of the system. By using a Simulink MATLAB, the system with the controller is stimulated and studied for different atmospheric conditions. We choose three irradiation levels of 1000, 800, and 600 W/m2 at a certain temperature of 25 ℃ and three values for the temperature of 20, 30,35 ℃ at irradiation level of 1000 W/m2 to calculate the efficiency of the algorithm. The extracted efficiency results are compared with the usual Perturb and Observe algorithm MPPT topology (P&O) for the same system design and atmospheric conditions. It was found to be the controller efficiency of the proposed algorithm is improved up to 99%. This improvement maximizes performance and reduces costs, provides adequate current and voltage, and minimizes booster losses, and improves booster reliability.

Enable a Facile Size Re-distribution of MBE-Grown Ga-Droplets via In Situ Pulsed Laser Shooting

A MBE-prepared Gallium (Ga)-droplet surface on GaAs (001) substrate is in situ irradiated by a single shot of UV pulsed laser. It demonstrates that laser shooting can facilely re-adjust the size of Ga-droplet and a special Ga-droplet of extremely broad size-distribution with width from 16 to 230 nm and height from 1 to 42 nm are successfully obtained. Due to the energetic inhomogeneity across the laser spot, the modification of droplet as a function of irradiation intensity (IRIT) can be straightly investigated on one sample and the correlated mechanisms are clarified. Systematically, the laser resizing can be perceived as: for low irradiation level, laser heating only expands droplets to make mergences among them, so in this stage, the droplet size distribution is solely shifted to the large side; for high irradiation level, laser irradiation not only causes thermal expansion but also thermal evaporation of Ga atom which makes the size-shift move to both sides. All of these size-shifts on Ga-droplets can be strongly controlled by applying different laser IRIT that enables a more designable droplet epitaxy in the future.

Study of crystallization behaviour of electron beam irradiated polypropylene and high-density polyethylene

The influence of electron-beam irradiation on polypropylene (PP) and high-density polyethylene (HDPE) was investigated with a focus on crystallization. A high-temperature (200°C) creep test revealed that the HDPE gradually increased cross-linking density in the range 30–120 kGy, while the PP underwent a chain scission which was quantitatively evaluated by gel permeation chromatography. The mechanical properties were measured in the range -150 to 200°C by a dynamic mechanical analysis. A small presence of C=C and C=O bonds was found in the irradiated PP by a Fourier transform infrared spectroscopy. Crystallization kinetics measured by differential scanning calorimetry and hot-stage optical microscopy results were influenced tremendously by irradiation for HDPE and to a lesser extent for PP. Irradiation caused a decrease in both the number of nucleation centres and the growth rate of individual spherulites. Crystallization was analysed in detail with the help of Hoffman–Lauritzen, Avrami and Arrhenius equations. Interestingly an increasing β -crystal formation with an increasing irradiation level was discovered for PP by X-ray diffraction. A generation of defects in the crystalline structure owing to irradiation was discussed.

Photovoltaic array maximum power point tracking via modified perturbation and observation algorithm

One drawback of PVs is their low efficiency. As the PVs have a unique maximum Power Point for a specified irradiation level, there must be an effective method for extracting maximum power from the PV module to raise the efficiency. Conventional Perturbation and Observation (P&O) is a simple algorithm for maximum power point tracking (MPPT) but it suffers from oscillation during steady state conditions and is deviated from the maximum power point during slow and rapid irradiation level change. This paper presents a modified P&O by adding variation in PV current as a third in addition to the voltage and power variation parameters. This new algorithm is capable of eliminating the MPPT deviation. To increase the perturbation speed, a double step is taken as the tracking is deviated from the MPP. The modified P&O algorithm is used to control the duty cycle of DC-DC buck converter. The simulation shows that the modified P&O is faster than the conventional. The power loss due to oscillation before attaining the steady state is less for modified P&O. For slow irradiation level change (ramp up 600 to 1000 and ramp down 1000-800) W/m2, the modified P&O shows less tracking diverge. As the irradiation level changes rapidly from 800 to 200 W/m2, it's shown that the modified algorithm attains the steady state faster than the conventional P&O and the average efficiency increased by 4.34%.

A hot Jupiter spectral sequence with evidence for compositional diversity

The emergent spectra of close-in, giant exoplanets ("hot Jupiters") are believed to be distinct from those of young gas giants and brown dwarfs with similar effective temperatures because these objects are primarily heated from above by their host stars rather than internally from the release of energy from their formation (Showman et al. 2020). Theoretical models predict a continuum of dayside spectra for hot Jupiters as a function of irradiation level, with the coolest planets having absorption features in their spectra, intermediate-temperature planets having emission features due to thermal inversions, and the hottest planets having blackbody-like spectra due to molecular dissociation and continuum opacity from the H- ion (Fortney et al. 2008, Parmentier et al. 2018, Arcangeli et al. 2018). Absorption and emission features have been detected in the spectra of a number of individual hot Jupiters (Kreidberg et al. 2014, Mikal-Evans et al. 2020), and population-level trends have been observed in photometric measurements (Keating et al. 2019, Baxter et al. 2020, Garhart et al. 2020, Dransfield et al. 2020). However, there has been no unified, population-level study of the thermal emission spectra of hot Jupiters such as has been done for brown dwarfs (Manjavacas et al. 2019) and transmission spectra of hot Jupiters (Sing et al. 2016). Here we show that hot Jupiter secondary eclipse spectra centered around a water absorption band at 1.4 microns follow a common trend in water feature strength with temperature. The observed trend is broadly consistent with the predictions of self-consistent one-dimensional models for how the thermal structures of solar composition planets vary with irradiation level. Nevertheless, the ensemble of planets exhibits significant scatter around the mean trend. The spread can be accounted for if the planets have modest variations in metallicity and/or elemental abundance ratios, which is expected from planet formation models (Mordasini et al. 2016, Ali-Dib et al. 2017, Madhusudhan et al. 2017, Cridland et al. 2019).

Modelling and Design Methodology of an Improved Performance Photovoltaic Pumping System Employing Ferrite Magnet Synchronous Reluctance Motors

This paper proposes a novel photovoltaic water pumping system (PVWPS) with an improved performance and cost. This system doesn’t contain a DC-DC converter, batteries nor rare-earth motors. Removing the aforementioned components will reduce the whole cost and increase the reliability of the system. For enhancing the performance of the PVWPS, a ferrite magnet synchronous reluctance motor (FMSynRM) is employed. Besides, the motor inverter is utilized to drive the motor properly and to extract the maximum available power of the PV system. This is performed using a suggested control strategy that controls the motor inverter. Furthermore, to show the effectiveness of the proposed PVWPS, the performance of the proposed system is benchmarked with a PVWPS that is employing a pure SynRM. Moreover, the complete mathematical model of the system components and the control is reported. It is proved that the flow rate employing the proposed system is increased by about 29.5% at a low irradiation level (0.25 kW/m2) and 15% at a high irradiation level (1 kW/m2) compared to the conventional solar system using a pure synchronous reluctance motor (SynRM). An experimental laboratory test bench is built to validate the theoretical results presented in this research work. Good agreement between the theoretical and the experimental results is proved.

Detection of 2-Dodecylcyclobutanone in Low-Dose Irradiated (0.5 Gy) Goose Fat by Triple-Quad GC-MS/MS

Aim of this work was the development of a sensitive procedure to detect low-dose irradiation in the scale of 0.5 Gy to 20 Gy in goose fat by detection of 2-dodecylcyclobutanone (2-DCB). The general procedure to detect 2-alkylcyclobutanone (2-ACB) according to EN 1785 was optimized by using acetonitrile for extraction of 2-DCB from the lipid fraction before clean-up with silica gel. Gas chromatographic separation was realized by a 15 m TG-5 HT column, and detection was done by using a triple-quad tandem-mass spectrometer in SRM-mode. At the irradiation level of 2 Gy, the optimized procedure showed high repeatability (3.9%), a good intermediate precision (20.9%) and an acceptable recovery rate of 57.8%, with 0.25 ng 2-DCB per gram of fat. With this procedure, a reliable proof of 2-DCB was possible for the irradiation intensities 20, 5 and 2 Gy for three mass transitions; for 0.5 Gy, a proof was possible for one mass transition.

X-ray irradiation and evaporation of the four young planets around V1298 Tau

ABSTRACT Planets around young stars are thought to undergo atmospheric evaporation due to the high magnetic activity of the host stars. Here we report on X-ray observations of V1298 Tau, a young star with four transiting exoplanets. We use X-ray observations of the host star with Chandra and ROSAT to measure the current high-energy irradiation level of the planets and employ a model for the stellar activity evolution together with exoplanetary mass-loss to estimate the possible evolution of the planets. We find that V1298 Tau is X-ray bright with log LX [erg s−1] = 30.1 and has a mean coronal temperature of ≈9 MK. This places the star amongst the more X-ray luminous ones at this stellar age. We estimate the radiation-driven mass-loss of the exoplanets and find that it depends sensitively on the possible evolutionary spin-down tracks of the star as well as on the current planetary densities. Assuming the planets are of low density due to their youth, we find that the innermost two planets can lose significant parts of their gaseous envelopes and could be evaporated down to their rocky cores depending on the stellar spin evolution. However, if the planets are heavier and follow the mass–radius relation of older planets, then even in the highest XUV irradiation scenario none of the planets is expected to cross the radius gap into the rocky regime until the system reaches an age of 5 Gyr.