• Energy Research

Abstract A novel solar concentrating PV and thermal (CPVT) combined system with beam splitter and compact concentrator structure is proposed in this study. The system structure and its design method are provided. The optical filter is designed and the incident light angle effect on the beam splitting performance is investigated. Solar concentrating simulations are conducted and the relevant results reveal that the CPVT combined system can provide a high solar concentration uniformity. The evaluation results of configuration and optical analyses indicate that when all the other parameters are settled, the optimal installation height of the solar receiver tube is 923.0 mm. The influence study of sun tracking accuracy on the system optical performance is launched. It is concluded that when the tracking error increases to 1.0°, the overall optical efficiency is 66.2%. The thermodynamic analysis results indicate that the PV conversion and overall energy efficiencies of the CPVT system are 30.5% and 26.6%, which are both higher than those of the normal CPV system. Moreover, the operating temperature effect investigation of solar thermal receiver tube is conducted. The results show that an optimal solar thermal receiver tube temperature (356.0 °C) exists, which can result in the maximum total output power.

The concentrated photovoltaic/thermal system (CPVT) adopting spectral beam splitting is a promising field of solar energy research. However, the thermo-electric properties of fluid-based CPVT collectors, which depend strongly on the non-uniform concentrated energy flux, remain unclear. This study aims to fill the gap and explore the thermo-electric properties of fluid-based CPVT collectors under non-uniform energy flux based on the finite volume method (FVM) with the Monte Carlo Ray-Trace (MCRT) method. The actual solar flux distribution on the receiver surface is obtained using Tracepro software. Then, the realistic non-uniform energy flux was employed in ANSYS Workbench 2022R1 software as a boundary condition to increase the accuracy of the CFD modeling of the system. The model is validated by comparing the results of the reference data. Moreover, the impact of uniform and non-uniform energy flux on the PV cell temperature is analyzed. In addition, the effects of mass flow rate on the electrical and thermal performance of the system are investigated. The results show that the PVT hybrid system has high conversion efficiency, with a total efficiency of more than 50%. Notably, the extreme non-uniformity of the solar-concentrated energy flux can result in local overheating of the PV cell, which may lead to irreversible damage.

The current study proposes a novel solar PV and thermal (PVT) system based on the combination of linear Fresnel reflector (LFR) concentrator and ITO-EG nano-fluids optical filter. Preparation and relevant measurements of the ITO nano-particles as well as the ITO-EG nano-fluids are conducted. The test results reveal that the optical filter has an average absorptivity of 30.9% in the spectrum range of 250.0–2500.0 nm. The solar concentration behaviour of the PVT system is revealed and the sensitivity analysis results of sun tracking error indicate that when the north-south tracking error is 0.2°, the overall optical efficiency is 90.12%, which means the PVT system has a relatively good adaptive faculty on sun tracking error. Theoretical thermodynamic calculation and CFD simulation methods are utilized to estimate the operation behaviour of the PVT system. The results demonstrate that the PVT system has a photoelectric conversion efficiency of 29.6% as well as a thermal efficiency of 18.52%. Parametric analysis results show that the thermal efficiency of the PVT system can be improved by increasing the inlet nano-fluids flow velocity as well as the ambient temperature, or by reducing the inlet nano-fluids temperature or convection heat transfer coefficient.

Abstract Spectral beam splitting technology based on optical nanofluids (NFs) is a promising field of solar energy research. However, the challenges to optimize the optical properties and enhance the high temperature stability of NFs are always exist. In this study, Indium Tin Oxide (ITO) nanoparticles were selected as the research object because of the excellent optical properties. The Oleylamine-capped ITO nanoparticles were prepared by chemical reduction. A novel NF based on Therminol 66 was successfully prepared. The high temperature stability and optical properties of obtained Oil-based NFs were analyzed by the gravitational sedimentation method and spectrophotometry. Moreover, we experimentally studied the effect of single reaction condition on the morphology and Sn-doping of particles. The results indicated that, at the reaction condition of 320 °C, 5.5 h, and the In/Sn mole ratio of 90:10, the obtained nanoparticles had high monodispersity and crystallinity, and the resulting NF had good stability and dispersion. Furthermore, when tuning single reaction condition, the morphology and Sn doping of nanoparticles tended to be a regular change. However, the change of single reaction condition was not enough to obtain the ITO NFs with good stability and dispersion. The ITO NFs obtained in present study had high thermal stability, and showed different high-temperature characteristics in the Ultraviolet and visible (UV–Vis) and near infrared (NIR) regions.

This study presents the design and performance evaluation of a novel concentration photovoltaic/thermal (PV/thermal) system based on parabolic trough concentrator and indium tin oxide-ethylene glycol (ITOEG) nanofluid spectral filter. The overall design principle of the PV/thermal system is introduced, and the ITOEG nanofluid spectral filter is prepared and experimentally tested. For the full spectrum, the average transmittance and absorbance of the nanofluid spectral filter are 69.1% and 30.9%. The optical behaviour evaluation results reveal a double-peak radiation flux density distribution on the nanofluid channel bottom surface as well as on the solar cell module surface. When the north-south sun-tracking error increases to 0.2°, the optical efficiency of the PV/thermal system decreases to 93.7%. That means the system has a relatively good adaptability to the sun-tracking error. The thermodynamic analysis results reveal that the theoretical photoelectric conversion and solar thermal efficiencies of the PV/thermal system are 29.1% and 17.2%. The thermal efficiency of the PV/thermal system can be increased by increasing the nanofluid inlet flow velocity or by decreasing the nanofluid inlet temperature properly.

Abstract Nanofluids (NFs) have been investigated as optical filters for photovoltaic/thermal applications, since they are more effective to produce heat with higher temperatures. However, the effect of temperature on both the stability and optical property of NFs has been little reported. In this work, we synthesized the SiO2-H2O NFs under different conditions and different nanoparticle volume fractions, and investigated the NF dispersion stability and optical properties at elevated temperatures. We analyzed the effects of several factors including the sonication temperature, the exposure temperature, the nanoparticle volume fraction and the exposure time. The results showed that reducing the maximum sonicating temperature during the NF fabrication process is beneficial to prolonging the NF stability, and the prepared NF stability was rather good with the maximum sonicating temperature of 30 °C. The absorptance of NFs decreased when the exposure temperature increased from 25 to 90 °C, and agglomeration more likely occurred for higher exposure temperatures. It is also found that the adding of nanoparticles helped to increase the spectrum absorption ability of NF. As a result, the overall energy efficiencies of the photovoltaic/thermal device using the NFs as the optical filter can be increased compared with that using the water filter.

En los últimos años, China ha estado promoviendo el proceso de neutralidad de carbono mediante el establecimiento de intercambios de carbono (CE) y la implementación de políticas relevantes de recompensa y castigo de emisiones de carbono. Este estudio propone una asociación de la CE, la planta de energía solar (SPP) y la planta de energía térmica a carbón (TPP). A partir del modelo de juego evolutivo tripartito y las políticas actuales de China, se simulan y discuten los procesos evolutivos. Los resultados revelan que se pueden lograr estados estables bajo diferentes modos de asociación. Los resultados de la evaluación del efecto de los parámetros típicos en los tres participantes muestran que bajo la premisa de asegurar las participaciones de CE y SPP, reducir adecuadamente los precios de la participación en las emisiones de carbono vendidas al TPP fortalecerá la voluntad de participación del TPP. Los rangos de precios de venta relativamente razonables de participación de emisiones de carbono del CE y SPP vendidos al TPP son 6.0∼6.2 $/t y 5.3∼5.5 $/t, respectivamente. Una mayor recompensa de cero emisiones de carbono y un mayor impuesto al carbono pueden fortalecer la voluntad de participación del TPP y hacer que el TPP logre la neutralidad de carbono. Este estudio puede proporcionar una referencia para que el gobierno y las industrias relacionadas promuevan el desarrollo neutro en carbono, así como el desarrollo coordinado de la energía solar y la energía térmica a carbón. Ces dernières années, la Chine a promu le processus de neutralité carbone en établissant des échanges de carbone (EC) et en mettant en œuvre des politiques pertinentes de récompense et de sanction des émissions de carbone. Cette étude propose un partenariat entre le CE, la centrale solaire (SPP) et la centrale thermique au charbon (TPP). Sur la base du modèle de jeu évolutif tripartite et des politiques actuelles de la Chine, les processus évolutifs sont simulés et discutés. Les résultats révèlent que des états stables peuvent être atteints sous différents modes de partenariat. Les résultats de l'évaluation de l'effet des paramètres typiques sur les trois participants montrent que, dans le but d'assurer la participation de CE et de SPP, une réduction appropriée des prix de la part des émissions de carbone vendue au TPP renforcera la volonté de participation du TPP. Les fourchettes de prix de vente relativement raisonnables de la part des émissions de carbone du CE et du SPP vendues au TPP sont de 6,0à6,2 $ / t et de 5,3à5,5 $ / t, respectivement. Une récompense zéro émission de carbone plus élevée et une taxe carbone plus élevée peuvent renforcer la volonté de participation du TPP et faire en sorte que le TPP atteigne la neutralité carbone. Cette étude peut servir de référence au gouvernement et aux industries connexes pour promouvoir le développement neutre en carbone ainsi que le développement coordonné de l'énergie solaire et de l'énergie thermique au charbon. In recent years, China has been promoting the process of carbon neutral by establishing carbon exchanges (CEs) and implementing relevant carbon emission reward and punishment policies. This study proposes a partnership of the CE, solar power plant (SPP) and coal-fired thermal power plant (TPP). Based on the tripartite evolutionary game model and current policies of China, the evolutionary processes are simulated and discussed. The results reveal that stable states can be achieved under different partnership modes. Effect evaluation results of typical parameters on the three participants show that on the premise of ensuring the participations of CE and SPP, properly reducing the prices of carbon emission share sold to the TPP will strengthen the participation willingness of TPP. The relatively reasonable selling price ranges of carbon emission share of the CE and SPP sold to the TPP are 6.0∼6.2 $/t and 5.3∼5.5 $/t, respectively. Higher zero carbon emission reward and higher carbon tax can strengthen the participation willingness of TPP and make the TPP achieve the carbon neutral. This study can provide a reference for the government and related industries to promote the carbon neutral development as well as the coordinated development of solar power and coal-fired thermal power. في السنوات الأخيرة، عززت الصين عملية تحييد الكربون من خلال إنشاء مبادلات الكربون (CEs) وتنفيذ سياسات المكافأة والعقاب ذات الصلة بانبعاثات الكربون. تقترح هذه الدراسة شراكة بين أوروبا الوسطى والشرقية ومحطة الطاقة الشمسية (SPP) ومحطة الطاقة الحرارية التي تعمل بالفحم (TPP). بناءً على نموذج اللعبة التطورية الثلاثية والسياسات الحالية للصين، تتم محاكاة العمليات التطورية ومناقشتها. تكشف النتائج أنه يمكن تحقيق حالات مستقرة في ظل أوضاع شراكة مختلفة. تُظهر نتائج تقييم تأثير المعلمات النموذجية على المشاركين الثلاثة أنه على فرضية ضمان مشاركة الاتحاد الأوروبي والمشتريات العامة المستدامة، فإن التخفيض المناسب لأسعار حصة انبعاثات الكربون المباعة إلى الشراكة عبر المحيط الهادئ سيعزز رغبة الشراكة عبر المحيط الهادئ في المشاركة. تبلغ نطاقات أسعار البيع المعقولة نسبيًا لحصة انبعاثات الكربون من CE و SPP المباعة إلى TPP 6.0 و 6.2 دولار/طن و 5.3 و 5.5 دولار/طن، على التوالي. يمكن أن تؤدي المكافأة الأعلى لانبعاثات الكربون الصفرية والضريبة الأعلى على الكربون إلى تعزيز رغبة الشراكة عبر المحيط الهادئ في المشاركة وجعل الشراكة عبر المحيط الهادئ تحقق الحياد الكربوني. يمكن أن توفر هذه الدراسة مرجعًا للحكومة والصناعات ذات الصلة لتعزيز التنمية المحايدة للكربون بالإضافة إلى التطوير المنسق للطاقة الشمسية والطاقة الحرارية التي تعمل بالفحم.