The theory of a glazed transpired collector solar air heater in natural convection mode has been developed. This was aimed at generating a framework for the experimental study of the performance of the collector. The theory involved the definition of some of the collector's main geometries, the formulation of the energy balance on the collector and the driving forces within the collector. Dimensional analysis was then applied to the formulations to obtain relationships between important dimensionless groups. The theory of the glazed transpired collector in natural convection mode provides a basis for the development of the collector for application in the areas of space heating and crop drying. This type of collector provides a solution to the challenge of space heating and crop drying at locations where electricity is not available and photovoltaic power is not affordable. It could also contribute to energy savings since it requires no electricity to work.
{"title":"THEORY OF A GLAZED TRANSPIRED SOLAR COLLECTOR IN NATURAL CONVECTION MODE","authors":"M. Ekoja, S. Onyegegbu, O. V. Ekechukwu","doi":"10.1115/1.4055300","DOIUrl":"https://doi.org/10.1115/1.4055300","url":null,"abstract":"\u0000 The theory of a glazed transpired collector solar air heater in natural convection mode has been developed. This was aimed at generating a framework for the experimental study of the performance of the collector. The theory involved the definition of some of the collector's main geometries, the formulation of the energy balance on the collector and the driving forces within the collector. Dimensional analysis was then applied to the formulations to obtain relationships between important dimensionless groups. The theory of the glazed transpired collector in natural convection mode provides a basis for the development of the collector for application in the areas of space heating and crop drying. This type of collector provides a solution to the challenge of space heating and crop drying at locations where electricity is not available and photovoltaic power is not affordable. It could also contribute to energy savings since it requires no electricity to work.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43044746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Solar energy will be the most sought-after source for generating electricity shortly because of its availability in abundance and pollution-free nature. Bifacial PV technology increases the power output through albedo effect. However, the major drawback of PV based power is that the efficiency is very low at less than 25%. The study focuses on the impact of surface color to explore the possibilities of enhancing the efficiency of solar modules considering the different terrace surface available in the residential region. The proposed work is one such attempt where the study is mainly focused on the impact of the surface properties on the extraction of electricity from the solar module without adopting the active techniques. A detailed study on different colors like Black, Green, and White is carried out. The study observed that white surface improves the albedo effect towards the rear surface of the module, thereby improving Energy Production Factor (EPF) and higher Life cycle conversion efficiency (LCE). It is observed that there is a 4.8 % increase in the average efficiency when using white as ground cover as compared to normal reference ground. The comparative study is also carried out for various lifetime period (T) like 10, 15, and 20 years. Calculated the Exergetic cost by considering operating periods like 15, 20, 25, and 30 years with 2%, 5%, and 10% interest rate, and it is observed that after 30 years of operation at 2% interest rate, energetic cost reached its highest value.
{"title":"A comprehensive 4E study on the performance of Bifacial solar module installed on different ground surface color: an Experimental study on a specific site","authors":"V. Muthu, G. Ramadas","doi":"10.1115/1.4055301","DOIUrl":"https://doi.org/10.1115/1.4055301","url":null,"abstract":"\u0000 Solar energy will be the most sought-after source for generating electricity shortly because of its availability in abundance and pollution-free nature. Bifacial PV technology increases the power output through albedo effect. However, the major drawback of PV based power is that the efficiency is very low at less than 25%. The study focuses on the impact of surface color to explore the possibilities of enhancing the efficiency of solar modules considering the different terrace surface available in the residential region. The proposed work is one such attempt where the study is mainly focused on the impact of the surface properties on the extraction of electricity from the solar module without adopting the active techniques. A detailed study on different colors like Black, Green, and White is carried out. The study observed that white surface improves the albedo effect towards the rear surface of the module, thereby improving Energy Production Factor (EPF) and higher Life cycle conversion efficiency (LCE). It is observed that there is a 4.8 % increase in the average efficiency when using white as ground cover as compared to normal reference ground. The comparative study is also carried out for various lifetime period (T) like 10, 15, and 20 years. Calculated the Exergetic cost by considering operating periods like 15, 20, 25, and 30 years with 2%, 5%, and 10% interest rate, and it is observed that after 30 years of operation at 2% interest rate, energetic cost reached its highest value.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43429129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Valiente-Blanco, D. López-Pascual, Pablo Diaz, R. Mallol-Poyato, A. Barragán, Manuel Ocaña, Guido Granello, E. Díez-Jiménez
Overheating of solar cells under normal operational conditions highly reduces their energy harvesting efficiency and produces additional problems related to thermal cycling and performance degradation of the modules. In this paper, a novel cooling system for solar photovoltaics, using the underground as a heat sink, is proposed, theoretically described and experimentally validated. A prototype of the technology (including a single-axis sun tracking mechanism) has been designed, manufactured, and rigorously tested in outdoor conditions during summer 2021 in Spain, under different environmental conditions. The excess heat is removed from the backside of the solar module by a close-loop and single-phase cooling system and then dissipated in the underground, which is at a constant temperature of about 16 °C at relatively low depths at the location where tests were performed. A single U-shaped copper tube, 18 mm in diameter, immersed in a 15.5 m deep borehole naturally filled with water, is used as an underground heat exchanger. As a consequence of the reduction of the cooled module temperature, its net power generation is significantly increased. A promising improvement of the net power generation of the cooled solar module up to 12.4% has been measured for a coolant flowrate of 1.84 l/min per square meter of solar module, proving the technical feasibility of the approach. In addition, a dependency of the power gain with the pump efficiency, the global radiation and ambient temperature has been observed.
{"title":"Efficiency improvement of photovoltaic solar modules by cooling using an underground heat exchanger","authors":"I. Valiente-Blanco, D. López-Pascual, Pablo Diaz, R. Mallol-Poyato, A. Barragán, Manuel Ocaña, Guido Granello, E. Díez-Jiménez","doi":"10.1115/1.4055299","DOIUrl":"https://doi.org/10.1115/1.4055299","url":null,"abstract":"\u0000 Overheating of solar cells under normal operational conditions highly reduces their energy harvesting efficiency and produces additional problems related to thermal cycling and performance degradation of the modules. In this paper, a novel cooling system for solar photovoltaics, using the underground as a heat sink, is proposed, theoretically described and experimentally validated. A prototype of the technology (including a single-axis sun tracking mechanism) has been designed, manufactured, and rigorously tested in outdoor conditions during summer 2021 in Spain, under different environmental conditions. The excess heat is removed from the backside of the solar module by a close-loop and single-phase cooling system and then dissipated in the underground, which is at a constant temperature of about 16 °C at relatively low depths at the location where tests were performed. A single U-shaped copper tube, 18 mm in diameter, immersed in a 15.5 m deep borehole naturally filled with water, is used as an underground heat exchanger. As a consequence of the reduction of the cooled module temperature, its net power generation is significantly increased. A promising improvement of the net power generation of the cooled solar module up to 12.4% has been measured for a coolant flowrate of 1.84 l/min per square meter of solar module, proving the technical feasibility of the approach. In addition, a dependency of the power gain with the pump efficiency, the global radiation and ambient temperature has been observed.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44774174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, thermal performance of a solar air heater (SAH) having broken arc-shaped ribs has been investigated experimentally and after that, performance parameters have been optimized. Study reveals that the use of artificial roughness enhances both, heat transfer rate and pumping power requirement and because of that, the overall performance of solar air heater increases. Thus, it is imperative to optimize the performance defining criteria viz. Nusselt number enhancement ratio, friction factor enhancement ratio and thermo-hydraulic performance parameter, in order to propose an optimal set of flow and roughness parameters. The hybrid Entropy-VIKOR technique has been employed to outline the optimal set of parameters using performance defining criterions, in order to get maximum profit with minimum incurred cost. The optimal set of parameters attained using Entropy- VIKOR approach among all the alternatives is: relative gap width = 4, relative roughness pitch = 10 and arc angle = 45° at Reynolds number = 9000.
{"title":"Experimental investigation and optimizing the parameters of a solar air heater having broken arc shaped ribs using hybrid Entropy-VIKOR technique","authors":"S. Jain, R. Misra, G. Agrawal","doi":"10.1115/1.4055297","DOIUrl":"https://doi.org/10.1115/1.4055297","url":null,"abstract":"\u0000 In this paper, thermal performance of a solar air heater (SAH) having broken arc-shaped ribs has been investigated experimentally and after that, performance parameters have been optimized. Study reveals that the use of artificial roughness enhances both, heat transfer rate and pumping power requirement and because of that, the overall performance of solar air heater increases. Thus, it is imperative to optimize the performance defining criteria viz. Nusselt number enhancement ratio, friction factor enhancement ratio and thermo-hydraulic performance parameter, in order to propose an optimal set of flow and roughness parameters. The hybrid Entropy-VIKOR technique has been employed to outline the optimal set of parameters using performance defining criterions, in order to get maximum profit with minimum incurred cost. The optimal set of parameters attained using Entropy- VIKOR approach among all the alternatives is: relative gap width = 4, relative roughness pitch = 10 and arc angle = 45° at Reynolds number = 9000.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45398926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Canneto, A. Tizzoni, S. Sau, E. Mansi, W. Gaggioli, A. Spadoni, N. Corsaro, M. Capocelli, G. Caputo, Francisca Galindo Paniagua, A. Della Libera
Parabolic trough concentrated solar power plants (PTCSP) are particularly promising renewable sources of energy, whose easy integration with Thermal Energy Storage (TES) systems allows to mitigate the intermittency of electricity generation. Currently, molten nitrates, with a two tanks arrangement, are mainly used for sensible heat accumulation. In order to reduce costs and make the CSP storage systems more manageable, single tank configurations have been proposed, where the cold and hot fluids are stored in the same container, and separated because of their density difference. The aim of the present work is to study the storage performances presented by two novel ternary and quaternary mixtures, proposed within the European project IN-POWER. An experimental campaign was preliminarily performed to investigate the fluids thermo-physical properties, and the obtained values were utilized as input data to model the discharge phase in a thermocline tank. The simulation results were compared with the ones acquired considering two commercial materials, namely, Solar Salt and Hitec XL®. Overall, considering same temperature ranges, higher discharging times are obtained for the quaternary and ternary mixtures, with the ternary presenting a smaller thermocline thickness than the solar salt while this parameter is the same considering the quaternary and Hitec XL®.
{"title":"Thermocline thermal storage for CSP applications: characterization of novel nitrate salt mixtures","authors":"G. Canneto, A. Tizzoni, S. Sau, E. Mansi, W. Gaggioli, A. Spadoni, N. Corsaro, M. Capocelli, G. Caputo, Francisca Galindo Paniagua, A. Della Libera","doi":"10.1115/1.4055295","DOIUrl":"https://doi.org/10.1115/1.4055295","url":null,"abstract":"\u0000 Parabolic trough concentrated solar power plants (PTCSP) are particularly promising renewable sources of energy, whose easy integration with Thermal Energy Storage (TES) systems allows to mitigate the intermittency of electricity generation. Currently, molten nitrates, with a two tanks arrangement, are mainly used for sensible heat accumulation. In order to reduce costs and make the CSP storage systems more manageable, single tank configurations have been proposed, where the cold and hot fluids are stored in the same container, and separated because of their density difference. The aim of the present work is to study the storage performances presented by two novel ternary and quaternary mixtures, proposed within the European project IN-POWER. An experimental campaign was preliminarily performed to investigate the fluids thermo-physical properties, and the obtained values were utilized as input data to model the discharge phase in a thermocline tank. The simulation results were compared with the ones acquired considering two commercial materials, namely, Solar Salt and Hitec XL®. Overall, considering same temperature ranges, higher discharging times are obtained for the quaternary and ternary mixtures, with the ternary presenting a smaller thermocline thickness than the solar salt while this parameter is the same considering the quaternary and Hitec XL®.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49230235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Unprecedented power outages and load shedding significantly impact power supply reliability in a power distribution network. Therefore, a hybrid renewable energy system (HRES) is developed, and its socio-techno-economic-environmental (STEE) viability in supplying reliable electricity to the village is being examined in this paper. STEE factor-based multi-target optimization and sizing technique is designed using the HOMER PRO software. The factors considered are namely social (land cost, human progress index, and employment generation factor), technical (unmet load, renewable energy portion, duty factor, and excess energy factor), economical (annualized cost of system, cost of energy, and total net present cost), and environmental (carbon emission and particulate matter). Three HRES setups are investigated, with various combinations of photovoltaic (PV), wind turbine (WT), battery (BAT), biogas generator (BG), and diesel generator (DG) and the optimal configuration is selected by STEE performance analysis. Compared to other evaluated setups, the HRES design with PV-WT-BAT-BG-DG is optimal for a consistent power supply. A sensitivity analysis for the optimal setup's macro-economic variables and component costs is performed to achieve a more feasible optimal setup. Furthermore, the optimal setup's cost of energy (0.1813 /kWh) is lower than that of the most recent study in the literature. The closeness of the HOMER results (cost of energy (0.1813/kWh) and particle swarm optimization results (cost of energy (0.1799 $/kWh)) for the optimal HRES setup supports the validity of the HOMER method used in this investigation.
{"title":"Optimal sizing of a hybrid renewable energy system: A sociotechno-economic-environmental perspective","authors":"P. Kushwaha, P. Ray, Chayan Bhattacharjee","doi":"10.1115/1.4055196","DOIUrl":"https://doi.org/10.1115/1.4055196","url":null,"abstract":"\u0000 Unprecedented power outages and load shedding significantly impact power supply reliability in a power distribution network. Therefore, a hybrid renewable energy system (HRES) is developed, and its socio-techno-economic-environmental (STEE) viability in supplying reliable electricity to the village is being examined in this paper. STEE factor-based multi-target optimization and sizing technique is designed using the HOMER PRO software. The factors considered are namely social (land cost, human progress index, and employment generation factor), technical (unmet load, renewable energy portion, duty factor, and excess energy factor), economical (annualized cost of system, cost of energy, and total net present cost), and environmental (carbon emission and particulate matter). Three HRES setups are investigated, with various combinations of photovoltaic (PV), wind turbine (WT), battery (BAT), biogas generator (BG), and diesel generator (DG) and the optimal configuration is selected by STEE performance analysis. Compared to other evaluated setups, the HRES design with PV-WT-BAT-BG-DG is optimal for a consistent power supply. A sensitivity analysis for the optimal setup's macro-economic variables and component costs is performed to achieve a more feasible optimal setup. Furthermore, the optimal setup's cost of energy (0.1813 /kWh) is lower than that of the most recent study in the literature. The closeness of the HOMER results (cost of energy (0.1813/kWh) and particle swarm optimization results (cost of energy (0.1799 $/kWh)) for the optimal HRES setup supports the validity of the HOMER method used in this investigation.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46737877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Devon Kesseli, Veena Chidurala, Ryan S Gooch, G. Zhu
Optical accuracy is a primary driver of parabolic trough concentrating solar power (CSP) plant performance, but can be damaged by wind, gravity, error during installation, and regular plant operation. Collecting and analyzing optical measurement over an entire operating parabolic trough plants is difficult, given the large scale of typical installations. The Distant Observer (DO) software tool uses images and video to measure surface slope in the parabolic mirror and absorber tube offset from the ideal focal point. DO has been adapted for fast data collection using low-cost commercial drones, but until recently still required substantial human labor to process large amounts of data. A new method leveraging deep learning and computer vision tools can drastically reduce the time required to process images. This method identifies the featureless corners of trough mirrors to a high degree of accuracy. Previous work has shown promising results using computer vision. The combined deep learning and computer vision approach presented here proved effective, and has the potential to further automate data collection and analysis, making the tool more robust. This method automatically identified 74.3% of mirror corners within 2 pixels of their manually marked counterparts and 91.9% within 3 pixels. This level of accuracy is sufficient for practical DO analysis within a target uncertainty. DO successfully analyzed video of over 100 parabolic trough modules collected at an operating CSP plant, and can provide plant operators and trough designers with valuable insight about plant performance, operating strategies, and plant-wide optical error trends.
{"title":"A Combined Computer Vision and Deep Learning Approach for Rapid Drone-Based Optical Characterization of Parabolic Troughs","authors":"Devon Kesseli, Veena Chidurala, Ryan S Gooch, G. Zhu","doi":"10.1115/1.4055172","DOIUrl":"https://doi.org/10.1115/1.4055172","url":null,"abstract":"\u0000 Optical accuracy is a primary driver of parabolic trough concentrating solar power (CSP) plant performance, but can be damaged by wind, gravity, error during installation, and regular plant operation. Collecting and analyzing optical measurement over an entire operating parabolic trough plants is difficult, given the large scale of typical installations. The Distant Observer (DO) software tool uses images and video to measure surface slope in the parabolic mirror and absorber tube offset from the ideal focal point. DO has been adapted for fast data collection using low-cost commercial drones, but until recently still required substantial human labor to process large amounts of data. A new method leveraging deep learning and computer vision tools can drastically reduce the time required to process images. This method identifies the featureless corners of trough mirrors to a high degree of accuracy. Previous work has shown promising results using computer vision. The combined deep learning and computer vision approach presented here proved effective, and has the potential to further automate data collection and analysis, making the tool more robust. This method automatically identified 74.3% of mirror corners within 2 pixels of their manually marked counterparts and 91.9% within 3 pixels. This level of accuracy is sufficient for practical DO analysis within a target uncertainty. DO successfully analyzed video of over 100 parabolic trough modules collected at an operating CSP plant, and can provide plant operators and trough designers with valuable insight about plant performance, operating strategies, and plant-wide optical error trends.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43199247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kai-Bei Luo, Zui Zeng, Weiliang Ye, Dengke Wu, Liu Jingtao
Disodium hydrogen phosphate dodecahydrate (DHPD) is a kind of phase-change hydrated material that has been widely used in heat-storage technology, but it has the common problems of supercooling and phase-separation of hydrated salts, therefore, the addition of a nucleating and thickening agent is a traditional method to solve the above problems. In this paper, sodium carboxymethylcellulose (CMC) and xanthan gum (XG) are used to improve the supercooling and phase-separation properties of the hydrated phase-change salts. The phase transition characteristics and cycling stability are analyzed in detail with the solidification curve, DSC (differential scanning calorimetry), XRD (x-ray diffraction), TG (thermal gravimetry), and thermal cycling experiments. The thickening water absorption of CMC and XG decreases the supercooling properties of DHPD without the addition of the nucleating agents. The addition of 5%XG together with 2%CMC reduce the supercooling of DHPD to 1.6 °C. DSC analysis showed that the additions can adsorb the free water, decrease the evaporation of crystalline water, and remove the self-phase separation problems. The phase-change temperature and latent heat were 36.2 °C and 201.5 J/g, respectively. The supercooling degree of the modified DHPD was no more than 2 °C, showing its excellent thermal stability in the accelerated thermal cycle experiments.
{"title":"Effect of the added thickening agents on the thermal and physical properties of the nucleating agent-free Na2HPO4·12H2O","authors":"Kai-Bei Luo, Zui Zeng, Weiliang Ye, Dengke Wu, Liu Jingtao","doi":"10.1115/1.4055129","DOIUrl":"https://doi.org/10.1115/1.4055129","url":null,"abstract":"\u0000 Disodium hydrogen phosphate dodecahydrate (DHPD) is a kind of phase-change hydrated material that has been widely used in heat-storage technology, but it has the common problems of supercooling and phase-separation of hydrated salts, therefore, the addition of a nucleating and thickening agent is a traditional method to solve the above problems. In this paper, sodium carboxymethylcellulose (CMC) and xanthan gum (XG) are used to improve the supercooling and phase-separation properties of the hydrated phase-change salts. The phase transition characteristics and cycling stability are analyzed in detail with the solidification curve, DSC (differential scanning calorimetry), XRD (x-ray diffraction), TG (thermal gravimetry), and thermal cycling experiments. The thickening water absorption of CMC and XG decreases the supercooling properties of DHPD without the addition of the nucleating agents. The addition of 5%XG together with 2%CMC reduce the supercooling of DHPD to 1.6 °C. DSC analysis showed that the additions can adsorb the free water, decrease the evaporation of crystalline water, and remove the self-phase separation problems. The phase-change temperature and latent heat were 36.2 °C and 201.5 J/g, respectively. The supercooling degree of the modified DHPD was no more than 2 °C, showing its excellent thermal stability in the accelerated thermal cycle experiments.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42694551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Distributed solar Photovoltaic (PV) generation is growing rapidly around the world. However, unlike conventional synchronous generators, PV systems do not have any rotating masses to deliver inertia to support the grid frequency. The paper presents a detailed modeling of a new converter configuration and control scheme to enable PV systems to adjust the real power output and contribute to the grid frequency regulation. The proposed topology consists of a two-stage converter without an energy storage system. A dc-dc buck converter is used instead of a dc-dc boost converter, and this simplifies the control scheme which aims to keep the PV generator power in the right side of the P-V characteristic and can be varied in the range from near-zero to the maximum power. The proposed control scheme combines robust and nonlinear sliding mode theory with fuzzy logic. The PV system is connected to a low inertia microgrid and its ability to contribute to frequency regulation is assessed for different controls. The proposed converter and its control are validated experimentally on a 3-kW PV system using OPAL-RT real-time simulator and tested under varying temperature, solar irradiance, and partial shading conditions. The results show that with the proposed circuit, the operating point is always on the right side of the P-V characteristic irrespective of the operating mode. Furthermore, the proposed control scheme provides PV generators with a fast and effective inertial response to support the grid and enhance its stability during contingencies.
{"title":"A Robust Control Approach for Frequency Support Capability of Grid-Tie Photovoltaic Systems","authors":"Sid Ahmed El Mehdi Ardjoun, M. Denai, H. Chafouk","doi":"10.1115/1.4055099","DOIUrl":"https://doi.org/10.1115/1.4055099","url":null,"abstract":"\u0000 Distributed solar Photovoltaic (PV) generation is growing rapidly around the world. However, unlike conventional synchronous generators, PV systems do not have any rotating masses to deliver inertia to support the grid frequency. The paper presents a detailed modeling of a new converter configuration and control scheme to enable PV systems to adjust the real power output and contribute to the grid frequency regulation. The proposed topology consists of a two-stage converter without an energy storage system. A dc-dc buck converter is used instead of a dc-dc boost converter, and this simplifies the control scheme which aims to keep the PV generator power in the right side of the P-V characteristic and can be varied in the range from near-zero to the maximum power. The proposed control scheme combines robust and nonlinear sliding mode theory with fuzzy logic. The PV system is connected to a low inertia microgrid and its ability to contribute to frequency regulation is assessed for different controls. The proposed converter and its control are validated experimentally on a 3-kW PV system using OPAL-RT real-time simulator and tested under varying temperature, solar irradiance, and partial shading conditions. The results show that with the proposed circuit, the operating point is always on the right side of the P-V characteristic irrespective of the operating mode. Furthermore, the proposed control scheme provides PV generators with a fast and effective inertial response to support the grid and enhance its stability during contingencies.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48007029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the rising penetration of photovoltaic (PV) plants on low voltage distribution systems, the generation of current harmonics as well as its impact on transformer operation is a current concern. The present research work develops a mathematical relationship of solar intensity (I(t)) with PV-inverter generated total harmonic distortion of current (THDi,inv.), and then uses IEEE recommendations to present the impact of THDi,inv on the life of a three-phase distribution transformer (TPDT). The validation of the presented model is done by real-time data monitoring from a 100 kWp solar rooftop photovoltaic (SRTPV) system, integrated with an 11 kV grid supply through a 63 kVA TPDT in the composite environment of north India. According to the results, decreasing I(t) values from 857 W/m2 to 35 W/m2 raises THDi,inv from 3.57% to 63.43%. It is also observed that the production of poor THDi,inv is high in winter season (daily average = 27.44%) in comparison to their values in summer season (daily average = 15.21%). For I(t) values less than 315 W/m2, the generation of large THDi,inv (above 15%) take place and it increases the loss of life (LoL) of TPDT by a factor of 6.0.
{"title":"Impact of Solar Intensity on PV Generated Current Harmonics and Transformer Life: A Mathematical Model with Experimental Validation","authors":"S. K. Rajput, D. K. Dheer","doi":"10.1115/1.4055101","DOIUrl":"https://doi.org/10.1115/1.4055101","url":null,"abstract":"\u0000 With the rising penetration of photovoltaic (PV) plants on low voltage distribution systems, the generation of current harmonics as well as its impact on transformer operation is a current concern. The present research work develops a mathematical relationship of solar intensity (I(t)) with PV-inverter generated total harmonic distortion of current (THDi,inv.), and then uses IEEE recommendations to present the impact of THDi,inv on the life of a three-phase distribution transformer (TPDT). The validation of the presented model is done by real-time data monitoring from a 100 kWp solar rooftop photovoltaic (SRTPV) system, integrated with an 11 kV grid supply through a 63 kVA TPDT in the composite environment of north India. According to the results, decreasing I(t) values from 857 W/m2 to 35 W/m2 raises THDi,inv from 3.57% to 63.43%. It is also observed that the production of poor THDi,inv is high in winter season (daily average = 27.44%) in comparison to their values in summer season (daily average = 15.21%). For I(t) values less than 315 W/m2, the generation of large THDi,inv (above 15%) take place and it increases the loss of life (LoL) of TPDT by a factor of 6.0.","PeriodicalId":17124,"journal":{"name":"Journal of Solar Energy Engineering-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49343410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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