Energies

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15 pages, 6598 KiB

Open AccessArticle

Trough-Type Free-Form Secondary Solar Concentrator for CPV/T Application

by Xian-long Meng, Fu-Peng Ren, Peng Zhang and Zi-xuan Tang

Energies 2022, 15(21), 8023; https://doi.org/10.3390/en15218023 - 28 Oct 2022

Cited by 1 | Viewed by 1182

Imaging concentrators like the parabolic trough solar concentrators have been widely employed for energy production in solar power plants. The conventional imaging solar concentrators form a non-uniform Gaussian distribution on receiving absorbers yielding the highest temperatures. The traditional CSP system normally truncated a [...] Read more.

Imaging concentrators like the parabolic trough solar concentrators have been widely employed for energy production in solar power plants. The conventional imaging solar concentrators form a non-uniform Gaussian distribution on receiving absorbers yielding the highest temperatures. The traditional CSP system normally truncated a peripheral region of heat flux to better use the central part. CPV/T systems using the waste heat recovery method can largely improve the total efficiency. However, for the CPV module, the coolant temperature was usually below 80 °C, which limited the applications of the thermal cycle such as the ORC system. In this article, a novel trough-type free-form secondary solar concentrator (TFSC) for PV/Thermal hybrid application has been proposed. Different from other CPV/T concepts using a combined PV panel and cooling tunnel/tube, the current concept separates the receiver in two parts. The secondary free-form reflector is generated by the geometric construction method, resulting in uniform heat flux in the edge region and high concentration in the central region. Through the ray tracing method, the optical properties have been verified. Sensitivity analysis of the concentrating structure is also conducted. The results provide supports for the design and applications of novel CPV/T systems. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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15 pages, 4776 KiB

Open AccessArticle

Investigation of Performance and Emission Characteristics of CI Engine Using Diesel and Waste Cooking Oil Blends

by Faheem Ahmed Solangi, Liaquat Ali Memon, Saleem Raza Samo, Muhammad Ramzan Luhur, Aqeel Ahmed Bhutto and Ali Murtaza Ansari

Energies 2022, 15(19), 7211; https://doi.org/10.3390/en15197211 - 30 Sep 2022

Cited by 2 | Viewed by 1668

Abstract

Reusing waste cooking oil (WCO) as fuel in compression ignition (CI) engine offers a sustainable solution for energy scarcity and environmental protection. WCO and n-pentanol ternary blends deliver are attractive prospects in utilization as bio-components and recycled components to moderately substitute diesel fuel. [...] Read more.

Reusing waste cooking oil (WCO) as fuel in compression ignition (CI) engine offers a sustainable solution for energy scarcity and environmental protection. WCO and n-pentanol ternary blends deliver are attractive prospects in utilization as bio-components and recycled components to moderately substitute diesel fuel. The current study intends to investigate the performance and emission characteristics of a single cylinder CI engine, having constant load at a uniform speed of 1300 rpm, using diesel-waste cooking oil n-pentanol blends. Blends chosen and analogized with diesel oil as reference fuel and their contents were the following: (1) D95-WCO5 (95%vol. diesel, WCO5%vol. waste cooking oil, (2) D65-WCO20-Pe15 (65%vol. diesel, 20%vol. waste cooking oil, and 15%vol. n-pentanol) and (3) D60-WCO20-Pe20 (60%vol. diesel, 20%vol. waste cooking oil and 20%vol. n-pentanol). The experimental results revealed that with the DF95-WCO5 blend the BSFC improved by 0.32%. However, with the addition of n-pentanol as a ternary blend; DF65-WCO20-Pe15 and DF60-WCO20-Pe20 resulted in improvements of 0.49% and 0.68% respectively. The BTE for DF95-WCO5 increased by 38.7%, while the increase was 39.2% for DF65-WCO20-Pe15 and 39.6% for DF60-WCO20-Pe20, which was less, as compared with diesel fuel. The lowermost level of CO discharge was achieved when the engine was fueled with DF65-WCO20-Pe15 and DF60-WCO20-Pe20, due to the highest level of saturation. CO₂, in the cases of DF65-WCO20-Pe15 and DF60-WCO20-Pe20, increased, as compared to diesel fuel under the same engine operating conditions. However, the binary blend DF95-WCO5 resulted in decreased CO₂ as analogized to diesel, because of incomplete combustion of the fuel. During experimental work it could be observed that the DF95-WCO5 binary blend produced higher Particulate material (PM-1, PM-2.5, PM-7 and PM-10) emissions, compared to DF100. Moreover, with the addition of n-pentanol as a ternary blend in the ratio of 15 to 20%, emission was further reduced. This indicated that direct exertion of WCO in engines must be promoted, as it is an impressive choice for waste recapture. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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18 pages, 4572 KiB

Open AccessArticle

Improved Whale Optimization Algorithm for Transient Response, Robustness, and Stability Enhancement of an Automatic Voltage Regulator System

by Salman Habib, Ghulam Abbas, Touqeer A. Jumani, Aqeel Ahmed Bhutto, Sohrab Mirsaeidi and Emad M. Ahmed

Energies 2022, 15(14), 5037; https://doi.org/10.3390/en15145037 - 10 Jul 2022

Cited by 36 | Viewed by 2466

Abstract

The proportional integral derivative (PID) controller is one of the most robust and simplest configuration controllers used for industrial applications. However, its performance purely depends on the tuning of its proportional (K_P), integral (K_I) and derivative (K_D) [...] Read more.

The proportional integral derivative (PID) controller is one of the most robust and simplest configuration controllers used for industrial applications. However, its performance purely depends on the tuning of its proportional (K_P), integral (K_I) and derivative (K_D) gains. Therefore, a proper combination of these gains is primarily required to achieve an optimal performance of the PID controllers. The conventional methods of PID tuning such as Cohen-Coon (CC) and Ziegler–Nichols (ZN) generate unwanted overshoots and long-lasting oscillations in the system. Owing to the mentioned problems, this paper attempts to achieve an optimized combination of PID controller gains by exploiting the intelligence of the whale optimization algorithm (WOA) and one of its recently introduced modified versions called improved whale optimization algorithm (IWOA) in an automatic voltage regulator (AVR) system. The stability of the IWOA-AVR system was studied by assessing its root-locus, bode maps, and pole/zero plots. The performance superiority of the presented IWOA-AVR design over eight of the recently explored AI-based approaches was validated through a comprehensive comparative analysis based on the most important transient response and stability metrics. Finally, to assess the robustness of the optimized AVR system, robustness analysis was conducted by analyzing the system response during the variation in the time constants of the generator, exciter, and amplifier from −50% to 50% range. The results of the study prove the superiority of the proposed IWOA-based AVR system in terms of transient response and stability metrics. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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11 pages, 2984 KiB

Open AccessArticle

Solar Energy Storage in an All-Vanadium Photoelectrochemical Cell: Structural Effect of Titania Nanocatalyst in Photoanode

by Hao Feng, Jian Liu, Ying Zhang and Dong Liu

Energies 2022, 15(12), 4508; https://doi.org/10.3390/en15124508 - 20 Jun 2022

Cited by 3 | Viewed by 2099

Abstract

Solar energy storage in the form of chemical energy is considered a promising alternative for solar energy utilization. High-performance solar energy conversion and storage significantly rely on the sufficient active surface area and the efficient transport of both reactants and charge carriers. Herein, [...] Read more.

Solar energy storage in the form of chemical energy is considered a promising alternative for solar energy utilization. High-performance solar energy conversion and storage significantly rely on the sufficient active surface area and the efficient transport of both reactants and charge carriers. Herein, the structure evolution of titania nanotube photocatalyst during the photoanode fabrication and its effect on photoelectrochemical activity in a microfluidic all-vanadium photoelectrochemical cell was investigated. Experimental results have shown that there exist opposite variation trends for the pore structure and crystallinity of the photocatalyst. With the increase in calcination temperature, the active surface area and pore volume were gradually declined while the crystallinity was significantly improved. The trade-off between the gradually deteriorated sintering and optimized crystallinity of the photocatalyst then determined the photoelectrochemical reaction efficiency. The optimal average photocurrent density and vanadium ions conversion rate emerged at an appropriate calcination temperature, where both the plentiful pores and large active surface area, as well as good crystallinity, could be ensured to promote the photoelectrochemical activity. This work reveals the structure evolution of the nanostructured photocatalyst in influencing the solar energy conversion and storage, which is useful for the structural design of the photoelectrodes in real applications. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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23 pages, 12045 KiB

Open AccessArticle

In-Depth Assessment and Optimized Actuation Method of a Novel Solar-Driven Thermomechanical Actuator via Shape Memory Alloy

by Ibrahim Khalil Almadani, Ibrahim Sufian Osman and Nasir Ghazi Hariri

Energies 2022, 15(10), 3807; https://doi.org/10.3390/en15103807 - 22 May 2022

Cited by 5 | Viewed by 2525

Abstract

Currently, energy demand is more significant than ever due to population growth and advances in recent technologies. In order to supply more energy while maintaining a healthy environment, renewable energy resources are employed. This paper proposes a novel solar-driven shape memory alloy thermomechanical [...] Read more.

Currently, energy demand is more significant than ever due to population growth and advances in recent technologies. In order to supply more energy while maintaining a healthy environment, renewable energy resources are employed. This paper proposes a novel solar-driven shape memory alloy thermomechanical actuator as an eco-friendly solution for solar thermal applications. The proposed actuator was assessed numerically and experimentally. The numerical tests showed that the designed actuation mechanism’s inner temperature has a minimum variation per day of about 14 °C and a temperature variation of 19 °C for most days of the year, which allows for proper activation and deactivation of the actuator. As for the experimental tests, the presented actuation mechanism achieved a bi-directional force of over 150 N, where the inner temperatures of the actuator were recorded at about 70.5 °C while pushing forces and 28.9 °C while pulling forces. Additionally, a displacement of about 127 mm was achieved as the internal temperature of the actuator reached 70.4 °C. The work presented adds to the body of knowledge of a novel solar-based self-driven actuation mechanism that facilitates various applications for solar thermal systems. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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11 pages, 3578 KiB

Open AccessArticle

Influence of As-N Interstitial Complexes on Strain Generated in GaAsN Epilayers Grown by AP-MOVPE

by Beata Ściana, Wojciech Dawidowski, Damian Radziewicz, Joanna Jadczak, Mari Cruz López-Escalante, Victor González de la Cruz and Mercedes Gabás

Energies 2022, 15(9), 3036; https://doi.org/10.3390/en15093036 - 21 Apr 2022

Cited by 4 | Viewed by 1815

Abstract

This work presents an investigation of the fully strained GaAsN/GaAs heterostructures obtained by atmospheric pressure metalorganic vapor phase epitaxy, focusing on the analysis of the strain generated in the GaAsN epilayers and its correlation with the formation of split interstitial complexes (N-As)_As [...] Read more.

This work presents an investigation of the fully strained GaAsN/GaAs heterostructures obtained by atmospheric pressure metalorganic vapor phase epitaxy, focusing on the analysis of the strain generated in the GaAsN epilayers and its correlation with the formation of split interstitial complexes (N-As)_As. We analyzed strained GaAsN epilayers with nitrogen contents and thicknesses varying from 0.93 to 1.81% and 65 to 130 nm, respectively. The composition and thickness were determined by high resolution X-ray diffraction, and the strain was determined by Raman spectroscopy, while the N-bonding configurations were determined by X-ray photoelectron spectroscopy. We found that the strain generated in the GaAsN epilayers is mainly caused by a lattice mismatch with the GaAs substrate. This macroscopic strain is independent of the amount of (N-As)_As interstitial defects, while the local strain, induced by an alloying effect, tends to decrease with an increasing ratio of (N-As)_As interstitial defects to substitutional nitrogen atoms incorporated into an arsenic sublattice—N_As. Here, we show experimentally, for the first time, a correlation between the strain in the GaAsN epilayers, caused by an alloying effect determined by Raman spectroscopy, and the (N-As)_As/N_As ratio estimated by the XPS method. We found out that the (N-As)_As interstitials compensate the local strain resulting from the presence of N in the GaAs matrix, if their amount does not exceed ~65% of the substitutional introduced nitrogen N_As. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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24 pages, 8375 KiB

Open AccessArticle

Performance Analysis of the 50 MW Concentrating Solar Power Plant under Various Operation Conditions

by Enkhbayar Shagdar, Bachirou Guene Lougou, Batmunkh Sereeter, Yong Shuai, Azeem Mustafa, Enkhjin Ganbold and Dongmei Han

Energies 2022, 15(4), 1367; https://doi.org/10.3390/en15041367 - 14 Feb 2022

Cited by 4 | Viewed by 3379

Abstract

Power generation using concentrating solar energy is a potential solution to provide clean, green, and sustainable power generation in the long term. The objective of this paper is to analyze the performance of a parabolic trough collector-based concentrating solar power (CSP) plant by [...] Read more.

Power generation using concentrating solar energy is a potential solution to provide clean, green, and sustainable power generation in the long term. The objective of this paper is to analyze the performance of a parabolic trough collector-based concentrating solar power (CSP) plant by selecting four different reference days (i.e., 22 March, 22 June, 22 September, and 22 December), representing four seasons in Mongolian climate conditions. Numerical simulation of the 50 MW CSP plant was performed, both at nominal and part-load conditions using the heat balance method considering variations of power load owing to the direct normal irradiation (DNI). The results revealed that the 50 MW CSP plant could operate well throughout the year, and it showed the highest value of operating performance for the 22 June due to the higher DNI and small solar incidence angle. The operating performance for the 22 March and 22 September is nearly similar. The lowest value of operating performance occurred on the 22 December. Moreover, the operating performance of the CSP plant in the part-load conditions was significantly reduced compared to the nominal load owing to the DNI fluctuation. This study also revealed that the CSP plant could significantly contribute to environmental protection and climate change mitigation. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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11 pages, 5424 KiB

Open AccessArticle

Compatibility of 3D-Printed Oxide Ceramics with Molten Chloride Salts for High-Temperature Thermal Energy Storage in Next-Generation CSP Plants

by Wenjin Ding, Yuan Shi, Markus Braun, Fiona Kessel, Martin Frieß, Alexander Bonk and Thomas Bauer

Energies 2021, 14(9), 2599; https://doi.org/10.3390/en14092599 - 1 May 2021

Cited by 5 | Viewed by 2449

Abstract

Oxide ceramics could be attractive high-temperature construction materials for critical structural parts in high-temperature molten salt thermal energy storage systems due to their excellent corrosion resistance and good mechanical properties. The 3D-printing technology allows the production of ceramic components with highly complex geometries, [...] Read more.

Oxide ceramics could be attractive high-temperature construction materials for critical structural parts in high-temperature molten salt thermal energy storage systems due to their excellent corrosion resistance and good mechanical properties. The 3D-printing technology allows the production of ceramic components with highly complex geometries, and therefore extends their applications. In this work, 3D-printed ZrO₂ and Al₂O₃ ceramics were immersed in molten MgCl₂/KCl/NaCl under argon or exposed in argon without molten chlorides at 700 °C for 600 h. Their material properties and microstructure were investigated through three-point-bend (3PB) testing and material analysis with SEM-EDX and XRD. The results show that the 3D-printed Al₂O₃ maintained its mechanical property after exposure in the strongly corrosive molten chloride salt. The 3D-printed ZrO₂ had an enhanced 3PB strength after molten salt exposure, whereas no change was observed after exposure in argon at 700 °C. The material analysis shows that some of the ZrO₂ on the sample surface changed its crystal structure and shape (T→M phase transformation) after molten salt exposure, which could be the reason for the enhanced 3PB strength. The thermodynamic calculation shows that the T→M transformation could be caused by the reaction of the Y₂O₃-stabilized ZrO₂ with MgCl₂ (mainly Y₂O₃ and ZrO₂ with gaseous MgCl₂). In conclusion, the 3D-printed ZrO₂ and Al₂O₃ ceramics have excellent compatibility with corrosive molten chlorides at high temperatures and thus show a sound application potential as construction materials for molten chlorides. Full article

(This article belongs to the Special Issue Advances in Solar Energy and Materials)

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