Fale Nogueira - Profile on Academia.edu (original) (raw)
Papers by Fale Nogueira
Seven Editora eBooks, Mar 15, 2024
Different models are applied for experimental and theoretical determination of the thermal and hy... more Different models are applied for experimental and theoretical determination of the thermal and hydraulic performance of gasket plate heat exchanger. One of the relevant aspects of recent works is the influence of the chevron inclination angle between the heat exchanger plates. This work aims to analyze the impact of the chevron inclination angle by applying effective concept in a sunflower vegetable oil cooler. Comparisons are made with theoretical and experimental results from the literature for works that consider angles of inclination equal to 30º, 45º, and 60º. An analysis model that does not consider the inclination angle an explicit parameter is included for comparison purposes. In addition to the angle of inclination, two other parameters, the mass flow rate of the cold fluid (water) and the number of plates, are considered crucial for determining and analyzing the results. Nusselt number, global heat transfer coefficient, effectiveness, heat transfer rate, and outlet temperatures for hot and cold fluids are presented graphical format. The results point to the need to improve models applied to gasket plate heat exchangers concerning the influence of the inclination angle since there are significant differences between those obtained and analyzed in this work.
Mechanical Engineering Advances, Oct 17, 2023
Mechanical Engineering Advances, Oct 16, 2023
The thermal efficiency of heat exchangers was applied for theoretical analysis of the thermal per... more The thermal efficiency of heat exchangers was applied for theoretical analysis of the thermal performance of a finned heat pipe heat exchanger (FHPHE) used as an auxiliary device to control the temperature and quality of the air conditioning in operating rooms. The theoretical analysis performed is punctual and distributed. It is divided into three aspects: analysis of the evaporator section, analysis of the condenser section, and analysis of the heat exchanger in terms of overall performance. The distributed procedure contrasts with the theoreticalexperimental study, which uses the concept of thermal effectiveness (ε-NTU) for global heat exchanger analysis. The developed approach considers the number of heat pipes, the number of fins, and the flow rate variation at the inlet of the heat exchanger as fundamental parameters for determining the thermophysical quantities of interest. Theoretical values were determined for the average velocities, Nusselt numbers, thermal effectiveness, heat transfer rates, and exit temperatures. The localized theoretical-experimental comparisons are consistent, and the absolute relative error for the global heat transfer rate ranges from 0.5% to 35%.
Mechanical Engineering Advances, Aug 20, 2023
The objective is to analyze the thermal and hydraulic performance in a Micro Channel Straight Pri... more The objective is to analyze the thermal and hydraulic performance in a Micro Channel Straight Printed Circuit Heat Exchanger. Counterflow and parallel flow configurations were analyzed for water cooling using ethylene glycol-based fluid and platelet-shaped nonspherical Boehmite alumina nanoparticles. The work presents results from applying a dimensionless theory that uses the concepts of thermal efficiency of heat exchangers and quantities associated with the second law of thermodynamics. Thermal efficiency, thermal effectiveness, thermal and viscous irreversibilities, thermodynamic Bejan number, and outlet water temperatures are presented in graph form. The data obtained allow us to conclude that the heat exchanger can work in a range of water and refrigerant flow rates below the design parameters. With the inclusion of nanoparticles with a volume fraction equal to 5.0%, the flow rates of the refrigerant fluid can be significantly reduced. The analysis performed shows that the use of nanoparticles improves the operational cost-benefit of the heat exchanger with a significant reduction in the hot water outlet temperature.
Engineering & Technology Scientific Journal
O objetivo é utilizar a análise adimensional através do método de eficiência térmica para determi... more O objetivo é utilizar a análise adimensional através do método de eficiência térmica para determinar o desempenho termo-hidráulico de um trocador de calor de placas espiral (S.P.H.E.) utilizado para resfriar óleo de girassol. O refrigerante consiste em água como fluido de base e nanopartículas não esféricas de Boehmite Alumina com uma fração de volume definida. O conceito de eficiência térmica para trocadores de calor é utilizado para determinar as principais grandezas utilizadas na análise. São apresentados resultados gráficos para o número de unidades térmicas (NTU), eficiência térmica, eficácia térmica, temperatura de saída do fluido quente, irreversibilidades térmicas e viscosas e número de Bejan. O trocador de calor analisado apresenta excelente desempenho térmico para refrigerantes constituídos por água e nanopartículas não esféricas em plaquetas ou cilíndricas, com fração volumétrica igual a 12,0%. A dissipação viscosa aumenta significativamente em relação à dissipação associ...
Acta Polytechnica, Dec 31, 2022
A descoberta do uso de superfícies estendidas (aletas) para aumentar a troca de energia em forma ... more A descoberta do uso de superfícies estendidas (aletas) para aumentar a troca de energia em forma de calor permitiu o bom funcionamento dos equipamentos que liberam este tipo de energia durante seu funcionamento, pois o aumento superficial de troca permite ter um ganho na taxa de transferência de energia na forma de calor, fazendo com que o equipamento tenha um rendimento maior e um aumento na sua vida útil. O uso de aletas é muito comum e bastante difundido na engenharia de projetos, muitas são as suas aplicações conhecidas como tubos de aparelhos de ar condicionado, motores de motocicletas, processadores de computadores e outros. Uma das aplicações industriais mais comuns de sistemas de aletas aparece em motores elétricos, que se tornaram um dos mais notórios inventos do homem ao longo de seu desenvolvimento tecnológico. Nesse trabalho apresentamos um estudo analítico do comportamento térmico de aletas de perfil retangular, onde utilizamos dados reais de um motor elétrico (modelo W...
Cadernos UniFOA, 2013
A análise do equilíbrio hidráulico de sistemas de distribuição de água malhados é baseada nas dua... more A análise do equilíbrio hidráulico de sistemas de distribuição de água malhados é baseada nas duas leis fundamentais da mecânica dos fluidos, a da continuidade (Lei de Conservação da Massa) e a da Lei de Conservação da Energia e, além disso, numa relação entre a vazão (ou velocidade) e a perda de carga (ou variação de pressão), estabelecida através das equações de Darcy - Weisbach (fórmula universal da perda de carga) ou Hazen - Williams. Em termos gerais, esta análise requer a resolução de um sistema de equações não lineares, frequentemente com um elevado número de incógnitas, dependendo da dimensão e da complexidade do sistema de distribuição de água em jogo. O primeiro método de solução aproximada para este tipo de problema (correções de vazões operadas individualmente para cada malha) foi apresentado por HARDY CROSS, no ano de 1936, sendo o mais antigo e, provavelmente, aquele que maior divulgação teve até o momento. O método de Hardy Cross é o mais utilizado dentre os métodos d...
– Fins or extended surfaces are extensively used in engineering applications to increase the effi... more – Fins or extended surfaces are extensively used in engineering applications to increase the efficiency of heat transfer of surfaces. Recent applications in compact heat exchangers increase interest in easy and applicable models for fin systems. A generalized one-dimensional radial fin model has been developed, where the modified power series expansion, the "Frobenius" method, is applied to a specific geometry. The comparison between two models, onedimensional and two-dimensional, was presented to determine the thermal characteristics in a simple fin system. The one-dimensional model is suitable for compact fin systems, where the ratio is relatively low (K ≤ 6) and the Biot number is not very high (Bi < 0.1). The results obtained are promising and motivating, leading to the conclusion that the implementation of the generalized model should be effective.
Journal of Engineering Sciences, 2021
The work analyzes the influence of the number of passes in a shell and tubes condenser heat excha... more The work analyzes the influence of the number of passes in a shell and tubes condenser heat exchanger, with an inlet pressure of R134a refrigerant in the shell equal to 1.2 MPa. The fluid that circulates in the tubes is water or water-based nanofluid with a fraction of aluminum oxide nanoparticles (Al2O3), and the methodology used subdivides the heat exchanger into three distinct regions: the overheated region, the saturated region, and the subcooled region. The main parameters used to analyze the thermal performance of the heat exchanger were efficiency and effectiveness. Efficiency in the superheated steam region is close to 1.0. There is scope for increasing thermal effectiveness, which can be improved with more significant passes in the tube. The saturated steam region process is efficient for lower mass flow rates of the fluid in the tube, but it is ineffective. However, it is highly effective for high mass flow rates. There is ample scope for increasing effectiveness in the su...
Journal of Engineering Sciences, 2020
The objective of the work is to obtain the outlet temperatures of the fluids in a shell and tube ... more The objective of the work is to obtain the outlet temperatures of the fluids in a shell and tube heat exchanger. The second law of thermodynamics is applied through the concepts of efficiency, effectiveness, and irreversibility to analyze the results. Water flows in the shell, and a mixture of water-ethylene glycol is associated with fractions of nanoparticles flows in the tube. Water enters the shell at 27 °C, and the mixture comes to the tube at 90 °C. The mass flow is kept fixed in the shell, equal to 0.23 kg/s, and varies between 0.01 kg/s to 0.50 kg/s. Volume fractions equal to 0.01, 0.10, and 0.25 were considered for analysis, for both nanoparticles from Ag and Al2O3. Results for Reynolds number, heat transfer rate, efficiency, effectiveness, and irreversibility are presented for critique, discussion, and justification of the output data found. It is shown that the flow regime has a significant effect on the performance of the analyzed heat exchanger. Keywords: thermodynamics,...
Journal of Engineering Sciences, 2020
Analytical solution for application and comparison of Graphene Nanoribbon and Silicon Carbide for... more Analytical solution for application and comparison of Graphene Nanoribbon and Silicon Carbide for thermal and hydraulic performance in flat tube Multi-Louvered Finned Radiator is presented. The base fluid is composed of pure water and ethylene glycol at a 50% volume fraction. The results were obtained for Nusselt number, convection heat transfer coefficient and pressure drop, for airflow in the radiator core and nanofluids in flat tubes. The main thermal and hydraulic parameters used are the Reynolds number, the mass flow rate, the Colburn Factor, and Friction Factor. In some situations, under analysis, the volume fraction, for Graphene Nanoribbon and Silicon Carbide, were varied. The value of the heat transfer coefficient obtained for Graphene Nanoribbon, for the volume fraction equal 0.05, is higher than twice the amount received by Silicon Carbide. The flow is laminar, for whatever the fraction value by volume of the Graphene nanoparticles when the mass flow of the nanofluid is r...
International Journal of Advanced Technology and Engineering Exploration, 2020
The objective of the work is to apply the analytical method of the effectiveness to analyze the t... more The objective of the work is to apply the analytical method of the effectiveness to analyze the thermal performance of the flat tube multi-louvered finned automotive radiator with silver nanoparticles suspension in ethylene glycol. All internal combustion engines produce heat and friction. This heat can have catastrophic effects on engine components. The existing methods employed to study and minimized this kind of combustion problem are analytical, experimental, and computational methods. The automotive radiator performance can be determined using the analytical method of effectiveness (ε-NTU) [1]. Sany et al. [2] carried out analytical and experimental work to obtain the Nusselt number and heat transfer coefficient. The effectiveness coefficient and the heat transfer coefficient are determined considering experimental data. The same procedures estimate the pressure drop and the Colburn factor for the radiator. Application examples demonstrated the utility of the method used. *Author for correspondence Properly dispersed nanoparticles provide an increase in the heat transfer surface between particles because nanofluids have a high specific surface area and high dispersion stability, with a predominant Brownian motion. Besides this, the use of extended surfaces for improving the efficiency of heat transfer is more effective, adding small solid particles to that fluid . Jing et al. [4] developed a new type of air-water heat exchanger to reduce the consumption of energy. The thermal performance and energy efficiency were analyzed and studied using the effectiveness number of transfer units (ε -NTU) method. The main conclusions obtained by the analysis are the air flow rate had a more considerable influence on the performance than the water flow rate and that the maximum heat transfer efficiency was 81.4% with Cmin/Cmax equal 0.25. Blecich et al. [5] presented a new method for fin-andtube heat exchangers operating with non-uniform airflow, which consists of discretizing the heat exchanger into tube elements. The results are compared against experimental data. They demonstrated that airflow nonuniformity causes effectiveness deterioration. The effectiveness deterioration depends on the number of heat transfer units (NTU) and the heat capacity rate ratio.
World Journal of Nano Science and Engineering, 2020
A theoretical analysis of the influence of the flow of a coolant containing silver nanoparticle (... more A theoretical analysis of the influence of the flow of a coolant containing silver nanoparticle (Ag) in an automotive radiator is presented. The coolant fluid is composed of water or an aqueous solution of Ethylene-Glycol (EG50%) and silver nanoparticles. Ethylene glycol (EG) has been used in automobile radiators for many years due to its compatibility with metals and its anti-cooling properties. Silver nanoparticles are being incorporated into the development of high-precision surgical equipment. It is shown that the rate of heat transfer increases significantly using silver nanoparticles and ethylene glycol and water. There is a maximum for heat exchange between fluids in all analyzed coolant flows-the maximum moves to higher airflow rates when the coolant flow rate is increased. However, the energy dissipation in the stream also increases, but the relationship between the energy dissipated in the flow and the energy transferred in the form of heat is low, which justifies the use of silver nanoparticles and ethylene glycol, or silver nanoparticles and water as a coolant in the automotive vehicle radiator.
International Journal for Research in Applied Science and Engineering Technology, 2019
Revista de Engenharia Térmica, 2018
In a gas-liquid annular two-phase flow one of the main factors influencing the determination of h... more In a gas-liquid annular two-phase flow one of the main factors influencing the determination of heat transfer rates is the average thickness of the liquid film. A model to accurately represent the heat transfer in such situations has to be able of determining the average liquid film thickness to within a reasonable accuracy. A typical physical aspect in gas-liquid annular flows is the appearance of interface waves, which affect heat, mass and momentum transfers. Existing models implicitly consider the wave effects in the momentum transfer by an empirical correlation for the interfacial friction factor. However, this procedure does not point out the difference between interface waves and the natural turbulent effects of the system. In the present work, the wave and mass transfer effects in the theoretical estimation of average liquid film thickness are analyzed, in comparison to a model that does not explicitly include these effects, as applied to the prediction of heat transfer rate...
Mechanical Engineering Advances, Sep 5, 2023
The objective is to use dimensionless analysis through the thermal efficiency method to determine... more The objective is to use dimensionless analysis through the thermal efficiency method to determine the thermohydraulic performance of a spiral plate heat exchanger (SPHE) used to cool sunflower oil. The coolant consists of water as a base fluid and non-spherical Boehmite Alumina nanoparticles with a defined volume fraction. The concept of thermal efficiency for heat exchangers is used to determine the main quantities used in the analysis. Graphical results are presented for the number of thermal units (NTU), thermal efficiency, thermal effectiveness, hot fluid outlet temperature, thermal and viscous irreversibilities, and Bejan number. The analyzed heat exchanger provides excellent thermal performance for refrigerants consisting of water and non-spherical nanoparticles in platelets or cylindrical, with a volume fraction equal to 12%. Viscous dissipation significantly increases concerning the dissipation associated with pure water, but the cost-benefit is within reason for the proposed objective, within the flow rate under analysis.
Mechanical Engineering Advances, Aug 20, 2023
A review of the concepts of thermal efficiency and thermal and hydraulic irreversibilities is pre... more A review of the concepts of thermal efficiency and thermal and hydraulic irreversibilities is presented, applying the second law of thermodynamics and thermodynamic Bejan number. An example problem, typical of thermal heat exchange between two fluids, is given, with a dimensionless solution for parallel and counterflow flows. The quantities of interest presented through the example are thermal efficiency, thermal effectiveness, thermal irreversibility, the relationship between outlet and inlet temperatures versus the number of thermal units, and outlet temperature for hot fluid. The theory presented in this review has been applied to numerous problems related to heat exchangers over the last three years, as per references.
Journal of Materials Science and Chemical Engineering
This work contributes to the improvement of energy-saving in air conditioning systems. The object... more This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat exchangers with individually finned heat pipes. The fundamental parameters used for performance analysis were the number of fins per heat pipe, the number of heat pipes, the inlet temperatures, and the flow rates of hot and cold fluids. The heat exchanger under analysis uses Freon 404A as a working fluid in an air conditioning system for cooling in the Evaporator and energy recovery in the Condenser. The theoretical model is localized and applied individually to the Evaporator, Condenser, and heat exchanger regions. The results obtained through the simulation are compared with experimental results that use a global approach for the heat exchanger. The thermal quantities obtained through the theoretical model in the mentioned regions are air velocity, Nusselt number, thermal effectiveness, heat transfer rate, and outlet temperature. The comparisons made with global experimental results are in excellent agreement, demonstrating that the localized theoretical approach developed is consistent and can be used as a comprehensive analysis tool for heat exchangers using heat pipes.
Seven Editora eBooks, Mar 15, 2024
Different models are applied for experimental and theoretical determination of the thermal and hy... more Different models are applied for experimental and theoretical determination of the thermal and hydraulic performance of gasket plate heat exchanger. One of the relevant aspects of recent works is the influence of the chevron inclination angle between the heat exchanger plates. This work aims to analyze the impact of the chevron inclination angle by applying effective concept in a sunflower vegetable oil cooler. Comparisons are made with theoretical and experimental results from the literature for works that consider angles of inclination equal to 30º, 45º, and 60º. An analysis model that does not consider the inclination angle an explicit parameter is included for comparison purposes. In addition to the angle of inclination, two other parameters, the mass flow rate of the cold fluid (water) and the number of plates, are considered crucial for determining and analyzing the results. Nusselt number, global heat transfer coefficient, effectiveness, heat transfer rate, and outlet temperatures for hot and cold fluids are presented graphical format. The results point to the need to improve models applied to gasket plate heat exchangers concerning the influence of the inclination angle since there are significant differences between those obtained and analyzed in this work.
Mechanical Engineering Advances, Oct 17, 2023
Mechanical Engineering Advances, Oct 16, 2023
The thermal efficiency of heat exchangers was applied for theoretical analysis of the thermal per... more The thermal efficiency of heat exchangers was applied for theoretical analysis of the thermal performance of a finned heat pipe heat exchanger (FHPHE) used as an auxiliary device to control the temperature and quality of the air conditioning in operating rooms. The theoretical analysis performed is punctual and distributed. It is divided into three aspects: analysis of the evaporator section, analysis of the condenser section, and analysis of the heat exchanger in terms of overall performance. The distributed procedure contrasts with the theoreticalexperimental study, which uses the concept of thermal effectiveness (ε-NTU) for global heat exchanger analysis. The developed approach considers the number of heat pipes, the number of fins, and the flow rate variation at the inlet of the heat exchanger as fundamental parameters for determining the thermophysical quantities of interest. Theoretical values were determined for the average velocities, Nusselt numbers, thermal effectiveness, heat transfer rates, and exit temperatures. The localized theoretical-experimental comparisons are consistent, and the absolute relative error for the global heat transfer rate ranges from 0.5% to 35%.
Mechanical Engineering Advances, Aug 20, 2023
The objective is to analyze the thermal and hydraulic performance in a Micro Channel Straight Pri... more The objective is to analyze the thermal and hydraulic performance in a Micro Channel Straight Printed Circuit Heat Exchanger. Counterflow and parallel flow configurations were analyzed for water cooling using ethylene glycol-based fluid and platelet-shaped nonspherical Boehmite alumina nanoparticles. The work presents results from applying a dimensionless theory that uses the concepts of thermal efficiency of heat exchangers and quantities associated with the second law of thermodynamics. Thermal efficiency, thermal effectiveness, thermal and viscous irreversibilities, thermodynamic Bejan number, and outlet water temperatures are presented in graph form. The data obtained allow us to conclude that the heat exchanger can work in a range of water and refrigerant flow rates below the design parameters. With the inclusion of nanoparticles with a volume fraction equal to 5.0%, the flow rates of the refrigerant fluid can be significantly reduced. The analysis performed shows that the use of nanoparticles improves the operational cost-benefit of the heat exchanger with a significant reduction in the hot water outlet temperature.
Engineering & Technology Scientific Journal
O objetivo é utilizar a análise adimensional através do método de eficiência térmica para determi... more O objetivo é utilizar a análise adimensional através do método de eficiência térmica para determinar o desempenho termo-hidráulico de um trocador de calor de placas espiral (S.P.H.E.) utilizado para resfriar óleo de girassol. O refrigerante consiste em água como fluido de base e nanopartículas não esféricas de Boehmite Alumina com uma fração de volume definida. O conceito de eficiência térmica para trocadores de calor é utilizado para determinar as principais grandezas utilizadas na análise. São apresentados resultados gráficos para o número de unidades térmicas (NTU), eficiência térmica, eficácia térmica, temperatura de saída do fluido quente, irreversibilidades térmicas e viscosas e número de Bejan. O trocador de calor analisado apresenta excelente desempenho térmico para refrigerantes constituídos por água e nanopartículas não esféricas em plaquetas ou cilíndricas, com fração volumétrica igual a 12,0%. A dissipação viscosa aumenta significativamente em relação à dissipação associ...
Acta Polytechnica, Dec 31, 2022
A descoberta do uso de superfícies estendidas (aletas) para aumentar a troca de energia em forma ... more A descoberta do uso de superfícies estendidas (aletas) para aumentar a troca de energia em forma de calor permitiu o bom funcionamento dos equipamentos que liberam este tipo de energia durante seu funcionamento, pois o aumento superficial de troca permite ter um ganho na taxa de transferência de energia na forma de calor, fazendo com que o equipamento tenha um rendimento maior e um aumento na sua vida útil. O uso de aletas é muito comum e bastante difundido na engenharia de projetos, muitas são as suas aplicações conhecidas como tubos de aparelhos de ar condicionado, motores de motocicletas, processadores de computadores e outros. Uma das aplicações industriais mais comuns de sistemas de aletas aparece em motores elétricos, que se tornaram um dos mais notórios inventos do homem ao longo de seu desenvolvimento tecnológico. Nesse trabalho apresentamos um estudo analítico do comportamento térmico de aletas de perfil retangular, onde utilizamos dados reais de um motor elétrico (modelo W...
Cadernos UniFOA, 2013
A análise do equilíbrio hidráulico de sistemas de distribuição de água malhados é baseada nas dua... more A análise do equilíbrio hidráulico de sistemas de distribuição de água malhados é baseada nas duas leis fundamentais da mecânica dos fluidos, a da continuidade (Lei de Conservação da Massa) e a da Lei de Conservação da Energia e, além disso, numa relação entre a vazão (ou velocidade) e a perda de carga (ou variação de pressão), estabelecida através das equações de Darcy - Weisbach (fórmula universal da perda de carga) ou Hazen - Williams. Em termos gerais, esta análise requer a resolução de um sistema de equações não lineares, frequentemente com um elevado número de incógnitas, dependendo da dimensão e da complexidade do sistema de distribuição de água em jogo. O primeiro método de solução aproximada para este tipo de problema (correções de vazões operadas individualmente para cada malha) foi apresentado por HARDY CROSS, no ano de 1936, sendo o mais antigo e, provavelmente, aquele que maior divulgação teve até o momento. O método de Hardy Cross é o mais utilizado dentre os métodos d...
– Fins or extended surfaces are extensively used in engineering applications to increase the effi... more – Fins or extended surfaces are extensively used in engineering applications to increase the efficiency of heat transfer of surfaces. Recent applications in compact heat exchangers increase interest in easy and applicable models for fin systems. A generalized one-dimensional radial fin model has been developed, where the modified power series expansion, the "Frobenius" method, is applied to a specific geometry. The comparison between two models, onedimensional and two-dimensional, was presented to determine the thermal characteristics in a simple fin system. The one-dimensional model is suitable for compact fin systems, where the ratio is relatively low (K ≤ 6) and the Biot number is not very high (Bi < 0.1). The results obtained are promising and motivating, leading to the conclusion that the implementation of the generalized model should be effective.
Journal of Engineering Sciences, 2021
The work analyzes the influence of the number of passes in a shell and tubes condenser heat excha... more The work analyzes the influence of the number of passes in a shell and tubes condenser heat exchanger, with an inlet pressure of R134a refrigerant in the shell equal to 1.2 MPa. The fluid that circulates in the tubes is water or water-based nanofluid with a fraction of aluminum oxide nanoparticles (Al2O3), and the methodology used subdivides the heat exchanger into three distinct regions: the overheated region, the saturated region, and the subcooled region. The main parameters used to analyze the thermal performance of the heat exchanger were efficiency and effectiveness. Efficiency in the superheated steam region is close to 1.0. There is scope for increasing thermal effectiveness, which can be improved with more significant passes in the tube. The saturated steam region process is efficient for lower mass flow rates of the fluid in the tube, but it is ineffective. However, it is highly effective for high mass flow rates. There is ample scope for increasing effectiveness in the su...
Journal of Engineering Sciences, 2020
The objective of the work is to obtain the outlet temperatures of the fluids in a shell and tube ... more The objective of the work is to obtain the outlet temperatures of the fluids in a shell and tube heat exchanger. The second law of thermodynamics is applied through the concepts of efficiency, effectiveness, and irreversibility to analyze the results. Water flows in the shell, and a mixture of water-ethylene glycol is associated with fractions of nanoparticles flows in the tube. Water enters the shell at 27 °C, and the mixture comes to the tube at 90 °C. The mass flow is kept fixed in the shell, equal to 0.23 kg/s, and varies between 0.01 kg/s to 0.50 kg/s. Volume fractions equal to 0.01, 0.10, and 0.25 were considered for analysis, for both nanoparticles from Ag and Al2O3. Results for Reynolds number, heat transfer rate, efficiency, effectiveness, and irreversibility are presented for critique, discussion, and justification of the output data found. It is shown that the flow regime has a significant effect on the performance of the analyzed heat exchanger. Keywords: thermodynamics,...
Journal of Engineering Sciences, 2020
Analytical solution for application and comparison of Graphene Nanoribbon and Silicon Carbide for... more Analytical solution for application and comparison of Graphene Nanoribbon and Silicon Carbide for thermal and hydraulic performance in flat tube Multi-Louvered Finned Radiator is presented. The base fluid is composed of pure water and ethylene glycol at a 50% volume fraction. The results were obtained for Nusselt number, convection heat transfer coefficient and pressure drop, for airflow in the radiator core and nanofluids in flat tubes. The main thermal and hydraulic parameters used are the Reynolds number, the mass flow rate, the Colburn Factor, and Friction Factor. In some situations, under analysis, the volume fraction, for Graphene Nanoribbon and Silicon Carbide, were varied. The value of the heat transfer coefficient obtained for Graphene Nanoribbon, for the volume fraction equal 0.05, is higher than twice the amount received by Silicon Carbide. The flow is laminar, for whatever the fraction value by volume of the Graphene nanoparticles when the mass flow of the nanofluid is r...
International Journal of Advanced Technology and Engineering Exploration, 2020
The objective of the work is to apply the analytical method of the effectiveness to analyze the t... more The objective of the work is to apply the analytical method of the effectiveness to analyze the thermal performance of the flat tube multi-louvered finned automotive radiator with silver nanoparticles suspension in ethylene glycol. All internal combustion engines produce heat and friction. This heat can have catastrophic effects on engine components. The existing methods employed to study and minimized this kind of combustion problem are analytical, experimental, and computational methods. The automotive radiator performance can be determined using the analytical method of effectiveness (ε-NTU) [1]. Sany et al. [2] carried out analytical and experimental work to obtain the Nusselt number and heat transfer coefficient. The effectiveness coefficient and the heat transfer coefficient are determined considering experimental data. The same procedures estimate the pressure drop and the Colburn factor for the radiator. Application examples demonstrated the utility of the method used. *Author for correspondence Properly dispersed nanoparticles provide an increase in the heat transfer surface between particles because nanofluids have a high specific surface area and high dispersion stability, with a predominant Brownian motion. Besides this, the use of extended surfaces for improving the efficiency of heat transfer is more effective, adding small solid particles to that fluid . Jing et al. [4] developed a new type of air-water heat exchanger to reduce the consumption of energy. The thermal performance and energy efficiency were analyzed and studied using the effectiveness number of transfer units (ε -NTU) method. The main conclusions obtained by the analysis are the air flow rate had a more considerable influence on the performance than the water flow rate and that the maximum heat transfer efficiency was 81.4% with Cmin/Cmax equal 0.25. Blecich et al. [5] presented a new method for fin-andtube heat exchangers operating with non-uniform airflow, which consists of discretizing the heat exchanger into tube elements. The results are compared against experimental data. They demonstrated that airflow nonuniformity causes effectiveness deterioration. The effectiveness deterioration depends on the number of heat transfer units (NTU) and the heat capacity rate ratio.
World Journal of Nano Science and Engineering, 2020
A theoretical analysis of the influence of the flow of a coolant containing silver nanoparticle (... more A theoretical analysis of the influence of the flow of a coolant containing silver nanoparticle (Ag) in an automotive radiator is presented. The coolant fluid is composed of water or an aqueous solution of Ethylene-Glycol (EG50%) and silver nanoparticles. Ethylene glycol (EG) has been used in automobile radiators for many years due to its compatibility with metals and its anti-cooling properties. Silver nanoparticles are being incorporated into the development of high-precision surgical equipment. It is shown that the rate of heat transfer increases significantly using silver nanoparticles and ethylene glycol and water. There is a maximum for heat exchange between fluids in all analyzed coolant flows-the maximum moves to higher airflow rates when the coolant flow rate is increased. However, the energy dissipation in the stream also increases, but the relationship between the energy dissipated in the flow and the energy transferred in the form of heat is low, which justifies the use of silver nanoparticles and ethylene glycol, or silver nanoparticles and water as a coolant in the automotive vehicle radiator.
International Journal for Research in Applied Science and Engineering Technology, 2019
Revista de Engenharia Térmica, 2018
In a gas-liquid annular two-phase flow one of the main factors influencing the determination of h... more In a gas-liquid annular two-phase flow one of the main factors influencing the determination of heat transfer rates is the average thickness of the liquid film. A model to accurately represent the heat transfer in such situations has to be able of determining the average liquid film thickness to within a reasonable accuracy. A typical physical aspect in gas-liquid annular flows is the appearance of interface waves, which affect heat, mass and momentum transfers. Existing models implicitly consider the wave effects in the momentum transfer by an empirical correlation for the interfacial friction factor. However, this procedure does not point out the difference between interface waves and the natural turbulent effects of the system. In the present work, the wave and mass transfer effects in the theoretical estimation of average liquid film thickness are analyzed, in comparison to a model that does not explicitly include these effects, as applied to the prediction of heat transfer rate...
Mechanical Engineering Advances, Sep 5, 2023
The objective is to use dimensionless analysis through the thermal efficiency method to determine... more The objective is to use dimensionless analysis through the thermal efficiency method to determine the thermohydraulic performance of a spiral plate heat exchanger (SPHE) used to cool sunflower oil. The coolant consists of water as a base fluid and non-spherical Boehmite Alumina nanoparticles with a defined volume fraction. The concept of thermal efficiency for heat exchangers is used to determine the main quantities used in the analysis. Graphical results are presented for the number of thermal units (NTU), thermal efficiency, thermal effectiveness, hot fluid outlet temperature, thermal and viscous irreversibilities, and Bejan number. The analyzed heat exchanger provides excellent thermal performance for refrigerants consisting of water and non-spherical nanoparticles in platelets or cylindrical, with a volume fraction equal to 12%. Viscous dissipation significantly increases concerning the dissipation associated with pure water, but the cost-benefit is within reason for the proposed objective, within the flow rate under analysis.
Mechanical Engineering Advances, Aug 20, 2023
A review of the concepts of thermal efficiency and thermal and hydraulic irreversibilities is pre... more A review of the concepts of thermal efficiency and thermal and hydraulic irreversibilities is presented, applying the second law of thermodynamics and thermodynamic Bejan number. An example problem, typical of thermal heat exchange between two fluids, is given, with a dimensionless solution for parallel and counterflow flows. The quantities of interest presented through the example are thermal efficiency, thermal effectiveness, thermal irreversibility, the relationship between outlet and inlet temperatures versus the number of thermal units, and outlet temperature for hot fluid. The theory presented in this review has been applied to numerous problems related to heat exchangers over the last three years, as per references.
Journal of Materials Science and Chemical Engineering
This work contributes to the improvement of energy-saving in air conditioning systems. The object... more This work contributes to the improvement of energy-saving in air conditioning systems. The objective is to apply the thermal efficiency of heat exchangers for localized determination of the thermal performance of heat exchangers with individually finned heat pipes. The fundamental parameters used for performance analysis were the number of fins per heat pipe, the number of heat pipes, the inlet temperatures, and the flow rates of hot and cold fluids. The heat exchanger under analysis uses Freon 404A as a working fluid in an air conditioning system for cooling in the Evaporator and energy recovery in the Condenser. The theoretical model is localized and applied individually to the Evaporator, Condenser, and heat exchanger regions. The results obtained through the simulation are compared with experimental results that use a global approach for the heat exchanger. The thermal quantities obtained through the theoretical model in the mentioned regions are air velocity, Nusselt number, thermal effectiveness, heat transfer rate, and outlet temperature. The comparisons made with global experimental results are in excellent agreement, demonstrating that the localized theoretical approach developed is consistent and can be used as a comprehensive analysis tool for heat exchangers using heat pipes.