Hakan Dumrul, Sezayi Yılmaz, Metin Kaya, I. Ceylan
In this study, a prototype system was established for location heating application and electricity generation through utilizing two concentrated photovoltaic thermal panels (CPV/T) possessing flat surface receivers connected in series with each other. The purpose of the system is to supply the heating needs of a room in winter season and to meet the electricity requirement of the equipment used in this system. In the analysis of the installed system, different refrigerants (10% mono propylene glycol + 90% water and 0.5% Al2O3-water nanofluid) were tested at three different flow rates (0.4 m3/h, 0.5 m3/h, 0.6 m3/h). Throughout the experiments, the fan-coil air outlet temperature used to heat the room was adjusted to 35 °C with an inverter and a process control device. The results attained from the experiments carried out using different fluids throughout different months and days (April-May) have demonstrated that the thermal and electrical efficiencies of the system are found to be in good agreement with each other when evaluated in terms of the fluids utilized. The highest electrical energy recovery was found as 268 W at 0.6 m3/h flow rate for propylene glycol-water mixture and 194 W at 0.5 m3/h flow rate for nanomixture. The total thermal energy efficiency for the system using different fluids was found to be around 22%. The total thermal energy gain of the system was also calculated as 2312 W at 0.6 m3/h for the propylene glycol mixture and 2041 W at 0.5 m3/h for the nanomixture.
{"title":"Energy Analysis of Concentrated Photovoltaic/Thermal Panels with Nanofluids","authors":"Hakan Dumrul, Sezayi Yılmaz, Metin Kaya, I. Ceylan","doi":"10.5541/ijot.882453","DOIUrl":"https://doi.org/10.5541/ijot.882453","url":null,"abstract":"In this study, a prototype system was established for location heating application and electricity generation through utilizing two concentrated photovoltaic thermal panels (CPV/T) possessing flat surface receivers connected in series with each other. The purpose of the system is to supply the heating needs of a room in winter season and to meet the electricity requirement of the equipment used in this system. In the analysis of the installed system, different refrigerants (10% mono propylene glycol + 90% water and 0.5% Al2O3-water nanofluid) were tested at three different flow rates (0.4 m3/h, 0.5 m3/h, 0.6 m3/h). Throughout the experiments, the fan-coil air outlet temperature used to heat the room was adjusted to 35 °C with an inverter and a process control device. The results attained from the experiments carried out using different fluids throughout different months and days (April-May) have demonstrated that the thermal and electrical efficiencies of the system are found to be in good agreement with each other when evaluated in terms of the fluids utilized. The highest electrical energy recovery was found as 268 W at 0.6 m3/h flow rate for propylene glycol-water mixture and 194 W at 0.5 m3/h flow rate for nanomixture. The total thermal energy efficiency for the system using different fluids was found to be around 22%. The total thermal energy gain of the system was also calculated as 2312 W at 0.6 m3/h for the propylene glycol mixture and 2041 W at 0.5 m3/h for the nanomixture.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46462554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Available data of the temperature dependence of the superconducting heat capacity and of the thermal conductivity of the conventional superconductors are analyzed in detail. It is shown that in contrast to the exponential function predicted by the BCS theory, the temperature dependence of the superconducting heat capacity consists of a sequence of a few analytically different universal power functions of absolute temperature. The changes from one to the next power function are typical examples of crossover events. The crossover occurring at the lowest temperature, commonly below about ~1 K, is identified as transition from Maxwell-Boltzmann to Bose-Einstein (BE) statistics of the Cooper-pairs. Because of the low mass of the Cooper pairs of 2m e (with m e as the mass of the electron) and their high density, the BE-condensation temperature, T BE , of the Cooper-pairs is about five orders of magnitude higher than for the dilute alkali atom condensates. The condensation temperature T BE turns out to be proportional to the superconducting transition temperature T SC . Since T BE is proportional to ~n 2/3 , with n as the density of the Cooper pairs at T BE , it is possible to obtain the density of the Cooper pairs at low temperatures. Assuming that for the type I superconductors the Cooper pairs form a dense gas of bosons with virtually no space between them, the diameter of the Cooper-pair orbital, calculated from n 2/3 , turns out to agree quantitatively with the experimental value of the London penetration depth. As a conclusion, due to the large orbital diamagnetism of the Cooper-pairs, only one layer of Cooper-pairs, next to the inner surface of the sample, is sufficient to shield an applied external magnetic field completely.
{"title":"Bose-Einstein Condensation of Cooper-Pairs in the Conventional Superconductors","authors":"U. Köbler","doi":"10.5541/ijot.899820","DOIUrl":"https://doi.org/10.5541/ijot.899820","url":null,"abstract":"Available data of the temperature dependence of the superconducting heat capacity and of the thermal conductivity of the conventional superconductors are analyzed in detail. It is shown that in contrast to the exponential function predicted by the BCS theory, the temperature dependence of the superconducting heat capacity consists of a sequence of a few analytically different universal power functions of absolute temperature. The changes from one to the next power function are typical examples of crossover events. The crossover occurring at the lowest temperature, commonly below about ~1 K, is identified as transition from Maxwell-Boltzmann to Bose-Einstein (BE) statistics of the Cooper-pairs. Because of the low mass of the Cooper pairs of 2m e (with m e as the mass of the electron) and their high density, the BE-condensation temperature, T BE , of the Cooper-pairs is about five orders of magnitude higher than for the dilute alkali atom condensates. The condensation temperature T BE turns out to be proportional to the superconducting transition temperature T SC . Since T BE is proportional to ~n 2/3 , with n as the density of the Cooper pairs at T BE , it is possible to obtain the density of the Cooper pairs at low temperatures. Assuming that for the type I superconductors the Cooper pairs form a dense gas of bosons with virtually no space between them, the diameter of the Cooper-pair orbital, calculated from n 2/3 , turns out to agree quantitatively with the experimental value of the London penetration depth. As a conclusion, due to the large orbital diamagnetism of the Cooper-pairs, only one layer of Cooper-pairs, next to the inner surface of the sample, is sufficient to shield an applied external magnetic field completely.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44589693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Online compressor washing is a promising method of preventing/ recovering the effect of fouling on compressor blades. However, proper strategies need to be implemented for online compressor washing to be effective since it is conducted when the engine is in operation. This study presents an experimental investigation of wash fluid preheating on the effectiveness of online compressor washing in a suction wind tunnel compressor cascade. Crude oil was uniformly applied on the compressor cascade blade surfaces using a roller brush, and consequently carborundum particles were ingested into the tunnel to create accelerated fouled blades. Demineralized water was preheated to 50 ⁰ C using a heat coil provided in the tank. Washing of the fouled blades were conducted using single flat fan nozzle, where the preheated and non-preheated demineralized water were used separately to wash the fouled blades. When fouled blades washed with preheated demineralized and the non-preheated were compared, it was observed that there was little or no difference in terms of total pressure loss coefficient and exit flow angle. However, when the fouled and washed cases were compared, there was a significant difference in total pressure loss coefficient and exit flow angle.
{"title":"Experimental Investigation of Wash Fluid Preheating on the effectiveness of online Compressor Washing in a Suction Tunnel Compressor Cascade","authors":"R. Agbadede, B. Kainga","doi":"10.5541/ijot.816320","DOIUrl":"https://doi.org/10.5541/ijot.816320","url":null,"abstract":"Online compressor washing is a promising method of preventing/ recovering the effect of fouling on compressor blades. However, proper strategies need to be implemented for online compressor washing to be effective since it is conducted when the engine is in operation. This study presents an experimental investigation of wash fluid preheating on the effectiveness of online compressor washing in a suction wind tunnel compressor cascade. Crude oil was uniformly applied on the compressor cascade blade surfaces using a roller brush, and consequently carborundum particles were ingested into the tunnel to create accelerated fouled blades. Demineralized water was preheated to 50 ⁰ C using a heat coil provided in the tank. Washing of the fouled blades were conducted using single flat fan nozzle, where the preheated and non-preheated demineralized water were used separately to wash the fouled blades. When fouled blades washed with preheated demineralized and the non-preheated were compared, it was observed that there was little or no difference in terms of total pressure loss coefficient and exit flow angle. However, when the fouled and washed cases were compared, there was a significant difference in total pressure loss coefficient and exit flow angle.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46230217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Performance Analysis of Gas Turbine Inlet Air Cooling Plant with Hybrid Indirect Evaporative Cooling and Absorption Chiller System","authors":"A. Moradi, Mina Masoomi, G. Salehi, M. K. Manesh","doi":"10.5541/ijot.840496","DOIUrl":"https://doi.org/10.5541/ijot.840496","url":null,"abstract":"","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44541995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thermodynamic Evaluation Of Solid Oxide Fuel Cells Converting Biogas Into Hydrogen And Electricity","authors":"Rafael Nogueira Nakashima, S. D. de Oliveira","doi":"10.5541/ijot.877847","DOIUrl":"https://doi.org/10.5541/ijot.877847","url":null,"abstract":"","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42863860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Study of Thermoelastic behaviour, Efficiency and Effectiveness of Rectangular Fin with Fractional Order Energy Balance Equation","authors":"J. Bikram","doi":"10.5541/ijot.879603","DOIUrl":"https://doi.org/10.5541/ijot.879603","url":null,"abstract":"","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46282192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present work, the laminar flow through a circular cylinder with two crossed splitter plates is analyzed. The characteristic-based method has been used along with the unstructured grid. The current research has been done to detect the proper conditions according to the geometrical parameters in which the optimal heat transfer is taking place. Geometric control parameters are the angle of splitter plates (theta) and the ratio of length of the splitter plate to cylinder radius (n=L/D). It was found that the use of a two-branched splitter plate is not wise in Reynolds number less than 100 due to its insignificant effect in flow properties. In angle 30° between two plates, the least drag force is witnessed with respect to other angles. Application of double branched splitter with angles more than 60° is not recommended, which will increase the total drag significantly. Since the splitter plate increases, the overall heat transfer from the cylinder and splitter set is enhanced. Minimum drag over the cylinder, and maximum convection drop from it is taken place when the dimension length is 0.75. Between dimensionless lengths 1.25 and 1.5, the Nusselt number oscillates with least amplitude and such behavior is also observed when two splitters are 60°apart.
{"title":"Thermo-flow Analysis of Cylinder with Crossed Splitter Plates with a Characteristics-based Scheme","authors":"S. Razavi, T. Adibi, Hussein Hassanpour","doi":"10.5541/IJOT.783614","DOIUrl":"https://doi.org/10.5541/IJOT.783614","url":null,"abstract":"In the present work, the laminar flow through a circular cylinder with two crossed splitter plates is analyzed. The characteristic-based method has been used along with the unstructured grid. The current research has been done to detect the proper conditions according to the geometrical parameters in which the optimal heat transfer is taking place. Geometric control parameters are the angle of splitter plates (theta) and the ratio of length of the splitter plate to cylinder radius (n=L/D). It was found that the use of a two-branched splitter plate is not wise in Reynolds number less than 100 due to its insignificant effect in flow properties. In angle 30° between two plates, the least drag force is witnessed with respect to other angles. Application of double branched splitter with angles more than 60° is not recommended, which will increase the total drag significantly. Since the splitter plate increases, the overall heat transfer from the cylinder and splitter set is enhanced. Minimum drag over the cylinder, and maximum convection drop from it is taken place when the dimension length is 0.75. Between dimensionless lengths 1.25 and 1.5, the Nusselt number oscillates with least amplitude and such behavior is also observed when two splitters are 60°apart.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47055958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Abedi, Gholamreza Salehi, M. Azad, M. K. Manesh, Hossein Fallahsohi
{"title":"Exergetic and Exergoeconomic Optimization of Gas Turbine Inlet Air Cooling Systems with Absorption or Compression Chilling","authors":"M. Abedi, Gholamreza Salehi, M. Azad, M. K. Manesh, Hossein Fallahsohi","doi":"10.5541/IJOT.785357","DOIUrl":"https://doi.org/10.5541/IJOT.785357","url":null,"abstract":"","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44048952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Faria, R. Santos, J. J. Santos, M. Barone, B. M. F. Miotto
In a productive process, the achievement of products occurs simultaneously with residues generation. Environmental impact of residues is an important issue in energy systems analysis due to environmental regulations and sustainability assessment. Many waste treatment methodologies have been proposed and applied in thermoeconomics. However, this is a complex problem and the solution depends on the residue nature and its formation process. Most conventional methodologies are based on productive diagrams, using productive flows only, and allocate the residues cost among the productive equipment. This work surveys the main conventional methodologies for treatment of waste and presents an improved/updated methodology based on a comprehensive diagram, in which both physical and productive flows are represented and their flows cost are assessed and the subsystems are connected using the same physical flows presented in the flowsheet of the plant. Both the CGAM system and a combined cycle are analyzed. Comparisons are made with literature results, considering the same case studies. The presented methodology obtains consistent results from the point of view of the cost allocation in thermoeconomics. The novelty of this updated approach concerns how the residue cost is allocated in the comprehensive diagram: it is reinternalized in the internal loop of physical flows, instead of in the productive unit. It represents advantages since the equipment product/fuel ratio index is not affected, which is beneficial for thermoeconomic diagnosis application.
{"title":"On the Allocation of Residues Cost using Conventional and Comprehensive Thermoeconomic Diagrams","authors":"P. Faria, R. Santos, J. J. Santos, M. Barone, B. M. F. Miotto","doi":"10.5541/IJOT.878173","DOIUrl":"https://doi.org/10.5541/IJOT.878173","url":null,"abstract":"In a productive process, the achievement of products occurs simultaneously with residues generation. Environmental impact of residues is an important issue in energy systems analysis due to environmental regulations and sustainability assessment. Many waste treatment methodologies have been proposed and applied in thermoeconomics. However, this is a complex problem and the solution depends on the residue nature and its formation process. Most conventional methodologies are based on productive diagrams, using productive flows only, and allocate the residues cost among the productive equipment. This work surveys the main conventional methodologies for treatment of waste and presents an improved/updated methodology based on a comprehensive diagram, in which both physical and productive flows are represented and their flows cost are assessed and the subsystems are connected using the same physical flows presented in the flowsheet of the plant. Both the CGAM system and a combined cycle are analyzed. Comparisons are made with literature results, considering the same case studies. The presented methodology obtains consistent results from the point of view of the cost allocation in thermoeconomics. The novelty of this updated approach concerns how the residue cost is allocated in the comprehensive diagram: it is reinternalized in the internal loop of physical flows, instead of in the productive unit. It represents advantages since the equipment product/fuel ratio index is not affected, which is beneficial for thermoeconomic diagnosis application.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41709334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, researchers have shown an increased interest in Cu-based shape memory alloys due to their special characteristics, which can be used in high-temperature applications. In this study, ternary shape memory alloys in the form of CuAlFe with different ratios of iron and quaternary CuAlFe alloys containing Ni, Mn, and Ti were produced by arc melting. Then the produced alloys were kept at 900 ℃ for 24 hours to make sure that all constituents in the alloys were homogeneously distributed. The change in the transformation temperatures for all samples was checked out by Differential Scanning Calorimetry (DSC). Also, the change in the crystal structure and microstructure were determined by x-ray diffractometer (XRD) and scanning electron microscopy (SEM), respectively. The aim of this study is to compare the thermal and microstructural properties of quaternary alloys formed by adding Ni, Mn, and Ti elements to CuAlFe-based shape memory alloy with different rates, which is not available in the literature. The result of this study; although the electron concentration value increased, a significant decrease was observed in the values of the transformation temperatures. Increasing Fe-element decreased the transformation temperature non-linearly. Ni and Mn contents added to CuAlFe shape memory alloys have reduced transformation temperatures, such as A f and M f. The XRD and SEM-EDX measurements showed the martensite phase with some produced compound precipitated in the matrix phase
{"title":"Quaternary Element Incorporation Effects on Thermal Properties and Crystal-Micro Structure of Cu-Al-Fe High Temperature Shape Memory Alloys","authors":"E. Balcı, S. Akpinar","doi":"10.5541/IJOT.805275","DOIUrl":"https://doi.org/10.5541/IJOT.805275","url":null,"abstract":"Recently, researchers have shown an increased interest in Cu-based shape memory alloys due to their special characteristics, which can be used in high-temperature applications. In this study, ternary shape memory alloys in the form of CuAlFe with different ratios of iron and quaternary CuAlFe alloys containing Ni, Mn, and Ti were produced by arc melting. Then the produced alloys were kept at 900 ℃ for 24 hours to make sure that all constituents in the alloys were homogeneously distributed. The change in the transformation temperatures for all samples was checked out by Differential Scanning Calorimetry (DSC). Also, the change in the crystal structure and microstructure were determined by x-ray diffractometer (XRD) and scanning electron microscopy (SEM), respectively. The aim of this study is to compare the thermal and microstructural properties of quaternary alloys formed by adding Ni, Mn, and Ti elements to CuAlFe-based shape memory alloy with different rates, which is not available in the literature. The result of this study; although the electron concentration value increased, a significant decrease was observed in the values of the transformation temperatures. Increasing Fe-element decreased the transformation temperature non-linearly. Ni and Mn contents added to CuAlFe shape memory alloys have reduced transformation temperatures, such as A f and M f. The XRD and SEM-EDX measurements showed the martensite phase with some produced compound precipitated in the matrix phase","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43742298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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