International Journal of Thermophysics, Jan 18, 2021
The present article deals with the computational fluid dynamics (CFD) investigation of flow and h... more The present article deals with the computational fluid dynamics (CFD) investigation of flow and heat transfer of a [C2mim][CH3SO3]/Al 2 O 3 ionanofluid in one conventional tube and two different grooved tubes. The flow is considered to be single-phase and laminar (500 < Re < 2000), and the range of nanoparticle concentration is between 0.05 and 2 %. For properties of the ionanofluid, experimental data available in the literature have been used. The results of relative heat transfer coefficient, pumping power, and field synergy are presented for the three different tubes at various Reynolds numbers and ionanofluid concentrations. It is found that the effect of grooves is more pronounced at low concentrations. Moreover, the heat transfer coefficient and pumping power rise by increasing the concentration. Adding the nanoparticles has a greater impact on the heat transfer at lower Reynolds numbers. The pumping power is intensified by the Re increment. More uniform temperature and velocity distributions are achieved because of the more severe flow mixing induced by the grooves. Both the greatest heat transfer coefficient and the highest pumping power occur for the tube having the spirally corrugated grooves. The results show that the heat transfer varies by changing the geometry. At a volume concentration of 0.05 % and Re = 500, the heat transfer coefficient increases by 15.54 % in the tube with the spirally corrugated grooves compared to the conventional tube.
Journal of Thermal Analysis and Calorimetry, Mar 23, 2021
In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematic... more In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematical modeling and prediction. In this analysis, the Levenberg–Marquardt backpropagation training algorithm is used to map the actual and the predicted value with the tansig activation function. The ANN model is developed to predict the engine performance and emission parameters for varying intake biogas–air mixture temperatures ranging from 55 ± 5 to 85 ± 5 °C under various load conditions. Around 70% of the total experimental data has been used for training, 15% for validation, and 15% for testing. The findings show higher coefficient of correlation (R, R2 and adjusted R2 values are in the range of 0.96–0.99) and lower mean square error (MSE = 0.0003515–0.00544501) for the developed ANN models. This study proves that ANN is an excellent tool for determining and optimizing the performance and emission parameters of compression ignition engines fuelled with alternative gaseous fuels.
This paper presents using density functional method to study nitrogen monoxide (NO) molecule phys... more This paper presents using density functional method to study nitrogen monoxide (NO) molecule physisorption with various concentrations on armchair graphene nanoribbon (GNR). We calculate the physical and electronic parameters of the GNR after nitrogen monoxide molecules adsorption. The Green's function method is used to obtain the electronic properties and electrical current through the ribbon. The GNR is considered as a channel of a back-gated field effect transistor (FET) to study the sensing properties of a graphene nanoribbon field effect (GNR-FET) sensor. Results show that the GNR is a suitable sensing layer for NO detection with different concentrations. Also, the current in the channel increases when NO molecules density is increased. To improve the sensitivity of the sensor, we apply a gate voltage to change the Fermi level of the channel. Obtained results prove that by applying back gate voltage to the channel of the sensor, the current and sensitivity of the sensor are improved simultaneously.
Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, the... more Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, these materials could be used as a medium to store the cold energy in air conditioning systems. Semiclathrate hydrates of tetra n-butylammonium bromide (TBAB) are favorable phase change materials (PCMs), due to their moderate hydrate formation conditions. The kinetics of carbon dioxide-TBAB semiclathrate hydrate formation in presence and absence of tween 80 as a non-anionic surfactant is investigated in this research. The experiments were performed in a 169 cm 3 stirred batch reactor at initial pressure of 3.2 MPa and isothermal condition of 276.15 K. Aqueous solutions of TBAB with concentrations of 0-15 wt% in presence and absence of tween 80 with concentrations of 500 and 1500 ppm are tested. The results revealed that utilization of TBAB with concentrations of 5-15 wt%, inhibits the kinetics of formed hydrates. By increasing the concentration of TBAB the amount and rate of gas uptake and storage capacity (SC) of formed hydrates decreases. Tween 80 with a concentration of 500 ppm presented a slight positive effect on the kinetics of hydrate formation in presence and absence of TBAB. While 1500 ppm of this additive inhibited the kinetics of formed hydrates.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011
In the present study, the applicability of widely used evaporation models (Dalton approach-based ... more In the present study, the applicability of widely used evaporation models (Dalton approach-based correlations) is experimentally investigated for natural, forced, and combined convection regimes. A series of experimental measurements are carried out over a wide range of water temperatures and air velocities for 0.01 ≤ Gr/Re2 ≤ 100 in a heated rectangular pool. The investigations show that the evaporation rate strongly depends on the convection regime's Gr/ Re2 value. The results show that the evaporation rate increases with the difference in vapour pressures over both forced convection (0.01 ≤ Gr/Re2 ≤ 0.1) and turbulent mixed convection regimes (0.15 ≤ Gr/Re2 ≤ 25). However, the escalation rate of evaporation decreases with Gr/ Re2 in the forced convection regime whereas in the turbulent mixed convection it increases. In addition, over the range of the free convection regime ( Gr/Re2 ≥ 25), the evaporation rate is affected not only by the vapour pressure difference but also by ...
Baiyangdian Lake is a typical and largest multi-habitat lake in the North plain of China. To unde... more Baiyangdian Lake is a typical and largest multi-habitat lake in the North plain of China. To understand the generation and transmission of antibiotics resistance genes (ARGs) in multi-habitat lakes, the contents of nutrients (TC, TOC, TN, TP and TS), heavy metals (Zn, Cr, Ni, Cu, Pb, As, Cd and Hg), 22 antibiotics, 16S-rRNA(16S), Class I integron (intI1) and 20 ARGs were determined. Samples were taken from the Fuhe river, river estuaries, reed marshes, living area, fish poods and open water of Baiyangdian Lake. The results showed that quinolones (QNs) were the main pollutants, and the content range was ND-104.94 ng/g. Thereinto, aac (6') -IB, blaTEM-1, ermF, qnrA, qnrD, tetG, sul1, sul2 and tetM were detected in 100%. The absolute abundance of sul1 was the highest (5.25×105copies/g-6.21×107 copies/g), which was the dominant ARGs. In these different habitats, the abundance of antibiotics and ARGs in river estuary was the highest, and that in reed marshes was the lowest. There was...
An experimental investigation on the effects of surface gravity waves on the water evaporation ra... more An experimental investigation on the effects of surface gravity waves on the water evaporation rate in different air flow regimes
In this study, by using nebulizer technology commonly used for the delivery of aerosolized drugs ... more In this study, by using nebulizer technology commonly used for the delivery of aerosolized drugs in pulmonary patients, the effect of injecting oil compounds and water vapor by nebulizer on the thermal efficiency and production of pollutants in gas emissions of natural gas diffusion flame is studied. The Nebulizer device creates micron incisions of injected liquid and, due to the reduced injection particle diameter, existing highly turbulent outflow and proper mixing of oil and water vapor compounds with gas and air inlet to the burner, effectiveness of the injection increases to enhance efficiency and reduce pollutants. In the experimental setup, the injection of 1 wt.% of oil compounds into the natural gas flame by a nebulizer improves thermal efficiency by 2.5%, decreases the temperature of the exhaust gases from the chimney by 12%, and also X NO pollutants by 13%, and increases carbon monoxide pollutant by 6%. Also, the injection of 2 wt.% of water drops as well as 1 wt.% of oil...
This paper presents using density functional method to study nitrogen monoxide (NO) molecule phys... more This paper presents using density functional method to study nitrogen monoxide (NO) molecule physisorption with various concentrations on armchair graphene nanoribbon (GNR). We calculate the physical and electronic parameters of the GNR after nitrogen monoxide molecules adsorption. The Green’s function method is used to obtain the electronic properties and electrical current through the ribbon. The GNR is considered as a channel of a back-gated field effect transistor (FET) to study the sensing properties of a graphene nanoribbon field effect (GNR-FET) sensor. Results show that the GNR is a suitable sensing layer for NO detection with different concentrations. Also, the current in the channel increases when NO molecules density is increased. To improve the sensitivity of the sensor, we apply a gate voltage to change the Fermi level of the channel. Obtained results prove that by applying back gate voltage to the channel of the sensor, the current and sensitivity of the sensor are imp...
In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematic... more In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematical modeling and prediction. In this analysis, the Levenberg–Marquardt backpropagation training algorithm is used to map the actual and the predicted value with the tansig activation function. The ANN model is developed to predict the engine performance and emission parameters for varying intake biogas–air mixture temperatures ranging from 55 ± 5 to 85 ± 5 °C under various load conditions. Around 70% of the total experimental data has been used for training, 15% for validation, and 15% for testing. The findings show higher coefficient of correlation (R, R2 and adjusted R2 values are in the range of 0.96–0.99) and lower mean square error (MSE = 0.0003515–0.00544501) for the developed ANN models. This study proves that ANN is an excellent tool for determining and optimizing the performance and emission parameters of compression ignition engines fuelled with alternative gaseous fuels.
Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, the... more Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, these materials could be used as a medium to store the cold energy in air conditioning systems. Semiclathrate hydrates of tetra n-butylammonium bromide (TBAB) are favorable phase change materials (PCMs), due to their moderate hydrate formation conditions. The kinetics of carbon dioxide - TBAB semiclathrate hydrate formation in presence and absence of tween 80 as a non-anionic surfactant is investigated in this research. The experiments were performed in a 169 cm3 stirred batch reactor at initial pressure of 3.2 MPa and isothermal condition of 276.15 K. Aqueous solutions of TBAB with concentrations of 0–15 wt% in presence and absence of tween 80 with concentrations of 500 and 1500 ppm are tested. The results revealed that utilization of TBAB with concentrations of 5–15 wt%, inhibits the kinetics of formed hydrates. By increasing the concentration of TBAB the amount and rate of gas uptake and...
Clathrate hydrate is a new technology to store the cold energy in air conditioning systems. These... more Clathrate hydrate is a new technology to store the cold energy in air conditioning systems. These compounds offer a high cold storage density. The phase change temperature of clathrate hydrates is more than water. On the other hand, these compounds offer better heat transfer properties and improved cyclic stability, compared to eutectic salts. These appropriate properties of clathrate hydrates made these compounds as promising potential for cold storage air conditioning systems. In this study, we investigated the refrigerant hydrate formation as a potential to store the cold energy. The equilibrium data reported by researchers are collected and the effect of various additives on their phase equilibria are investigated. A comparison between the dissociation pressure of hydrate formed in presence of some refrigerant are undertaken. Finally, the various methods of hydrate-based refrigeration systems reported in literature are collected along with their advantages and drawbacks.
The present article deals with the computational fluid dynamics (CFD) investigation of flow and h... more The present article deals with the computational fluid dynamics (CFD) investigation of flow and heat transfer of a [C2mim][CH3SO3]/Al 2 O 3 ionanofluid in one conventional tube and two different grooved tubes. The flow is considered to be single-phase and laminar (500 < Re < 2000), and the range of nanoparticle concentration is between 0.05 and 2 %. For properties of the ionanofluid, experimental data available in the literature have been used. The results of relative heat transfer coefficient, pumping power, and field synergy are presented for the three different tubes at various Reynolds numbers and ionanofluid concentrations. It is found that the effect of grooves is more pronounced at low concentrations. Moreover, the heat transfer coefficient and pumping power rise by increasing the concentration. Adding the nanoparticles has a greater impact on the heat transfer at lower Reynolds numbers. The pumping power is intensified by the Re increment. More uniform temperature and velocity distributions are achieved because of the more severe flow mixing induced by the grooves. Both the greatest heat transfer coefficient and the highest pumping power occur for the tube having the spirally corrugated grooves. The results show that the heat transfer varies by changing the geometry. At a volume concentration of 0.05 % and Re = 500, the heat transfer coefficient increases by 15.54 % in the tube with the spirally corrugated grooves compared to the conventional tube.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011
In the present study, the applicability of widely used evaporation models (Dalton approach-based ... more In the present study, the applicability of widely used evaporation models (Dalton approach-based correlations) is experimentally investigated for natural, forced, and combined convection regimes. A series of experimental measurements are carried out over a wide range of water temperatures and air velocities for 0:01 Gr=Re 2 100 in a heated rectangular pool. The investigations show that the evaporation rate strongly depends on the convection regime's Gr/Re 2 value. The results show that the evaporation rate increases with the difference in vapour pressures over both forced convection (0:01 Gr=Re 2 0:1) and turbulent mixed convection regimes (0:15 Gr=Re 2 25). However, the escalation rate of evaporation decreases with Gr/Re 2 in the forced convection regime whereas in the turbulent mixed convection it increases. In addition, over the range of the free convection regime (Gr=Re 2 ! 25), the evaporation rate is affected not only by the vapour pressure difference but also by the density variation. A dimensionless correlation using the experimental data of all convection regimes (0:01 Gr=Re 2 100) is proposed to cover different water surface geometries and airflow conditions.
International Journal of Thermophysics, Jan 18, 2021
The present article deals with the computational fluid dynamics (CFD) investigation of flow and h... more The present article deals with the computational fluid dynamics (CFD) investigation of flow and heat transfer of a [C2mim][CH3SO3]/Al 2 O 3 ionanofluid in one conventional tube and two different grooved tubes. The flow is considered to be single-phase and laminar (500 < Re < 2000), and the range of nanoparticle concentration is between 0.05 and 2 %. For properties of the ionanofluid, experimental data available in the literature have been used. The results of relative heat transfer coefficient, pumping power, and field synergy are presented for the three different tubes at various Reynolds numbers and ionanofluid concentrations. It is found that the effect of grooves is more pronounced at low concentrations. Moreover, the heat transfer coefficient and pumping power rise by increasing the concentration. Adding the nanoparticles has a greater impact on the heat transfer at lower Reynolds numbers. The pumping power is intensified by the Re increment. More uniform temperature and velocity distributions are achieved because of the more severe flow mixing induced by the grooves. Both the greatest heat transfer coefficient and the highest pumping power occur for the tube having the spirally corrugated grooves. The results show that the heat transfer varies by changing the geometry. At a volume concentration of 0.05 % and Re = 500, the heat transfer coefficient increases by 15.54 % in the tube with the spirally corrugated grooves compared to the conventional tube.
Journal of Thermal Analysis and Calorimetry, Mar 23, 2021
In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematic... more In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematical modeling and prediction. In this analysis, the Levenberg–Marquardt backpropagation training algorithm is used to map the actual and the predicted value with the tansig activation function. The ANN model is developed to predict the engine performance and emission parameters for varying intake biogas–air mixture temperatures ranging from 55 ± 5 to 85 ± 5 °C under various load conditions. Around 70% of the total experimental data has been used for training, 15% for validation, and 15% for testing. The findings show higher coefficient of correlation (R, R2 and adjusted R2 values are in the range of 0.96–0.99) and lower mean square error (MSE = 0.0003515–0.00544501) for the developed ANN models. This study proves that ANN is an excellent tool for determining and optimizing the performance and emission parameters of compression ignition engines fuelled with alternative gaseous fuels.
This paper presents using density functional method to study nitrogen monoxide (NO) molecule phys... more This paper presents using density functional method to study nitrogen monoxide (NO) molecule physisorption with various concentrations on armchair graphene nanoribbon (GNR). We calculate the physical and electronic parameters of the GNR after nitrogen monoxide molecules adsorption. The Green's function method is used to obtain the electronic properties and electrical current through the ribbon. The GNR is considered as a channel of a back-gated field effect transistor (FET) to study the sensing properties of a graphene nanoribbon field effect (GNR-FET) sensor. Results show that the GNR is a suitable sensing layer for NO detection with different concentrations. Also, the current in the channel increases when NO molecules density is increased. To improve the sensitivity of the sensor, we apply a gate voltage to change the Fermi level of the channel. Obtained results prove that by applying back gate voltage to the channel of the sensor, the current and sensitivity of the sensor are improved simultaneously.
Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, the... more Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, these materials could be used as a medium to store the cold energy in air conditioning systems. Semiclathrate hydrates of tetra n-butylammonium bromide (TBAB) are favorable phase change materials (PCMs), due to their moderate hydrate formation conditions. The kinetics of carbon dioxide-TBAB semiclathrate hydrate formation in presence and absence of tween 80 as a non-anionic surfactant is investigated in this research. The experiments were performed in a 169 cm 3 stirred batch reactor at initial pressure of 3.2 MPa and isothermal condition of 276.15 K. Aqueous solutions of TBAB with concentrations of 0-15 wt% in presence and absence of tween 80 with concentrations of 500 and 1500 ppm are tested. The results revealed that utilization of TBAB with concentrations of 5-15 wt%, inhibits the kinetics of formed hydrates. By increasing the concentration of TBAB the amount and rate of gas uptake and storage capacity (SC) of formed hydrates decreases. Tween 80 with a concentration of 500 ppm presented a slight positive effect on the kinetics of hydrate formation in presence and absence of TBAB. While 1500 ppm of this additive inhibited the kinetics of formed hydrates.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011
In the present study, the applicability of widely used evaporation models (Dalton approach-based ... more In the present study, the applicability of widely used evaporation models (Dalton approach-based correlations) is experimentally investigated for natural, forced, and combined convection regimes. A series of experimental measurements are carried out over a wide range of water temperatures and air velocities for 0.01 ≤ Gr/Re2 ≤ 100 in a heated rectangular pool. The investigations show that the evaporation rate strongly depends on the convection regime's Gr/ Re2 value. The results show that the evaporation rate increases with the difference in vapour pressures over both forced convection (0.01 ≤ Gr/Re2 ≤ 0.1) and turbulent mixed convection regimes (0.15 ≤ Gr/Re2 ≤ 25). However, the escalation rate of evaporation decreases with Gr/ Re2 in the forced convection regime whereas in the turbulent mixed convection it increases. In addition, over the range of the free convection regime ( Gr/Re2 ≥ 25), the evaporation rate is affected not only by the vapour pressure difference but also by ...
Baiyangdian Lake is a typical and largest multi-habitat lake in the North plain of China. To unde... more Baiyangdian Lake is a typical and largest multi-habitat lake in the North plain of China. To understand the generation and transmission of antibiotics resistance genes (ARGs) in multi-habitat lakes, the contents of nutrients (TC, TOC, TN, TP and TS), heavy metals (Zn, Cr, Ni, Cu, Pb, As, Cd and Hg), 22 antibiotics, 16S-rRNA(16S), Class I integron (intI1) and 20 ARGs were determined. Samples were taken from the Fuhe river, river estuaries, reed marshes, living area, fish poods and open water of Baiyangdian Lake. The results showed that quinolones (QNs) were the main pollutants, and the content range was ND-104.94 ng/g. Thereinto, aac (6') -IB, blaTEM-1, ermF, qnrA, qnrD, tetG, sul1, sul2 and tetM were detected in 100%. The absolute abundance of sul1 was the highest (5.25×105copies/g-6.21×107 copies/g), which was the dominant ARGs. In these different habitats, the abundance of antibiotics and ARGs in river estuary was the highest, and that in reed marshes was the lowest. There was...
An experimental investigation on the effects of surface gravity waves on the water evaporation ra... more An experimental investigation on the effects of surface gravity waves on the water evaporation rate in different air flow regimes
In this study, by using nebulizer technology commonly used for the delivery of aerosolized drugs ... more In this study, by using nebulizer technology commonly used for the delivery of aerosolized drugs in pulmonary patients, the effect of injecting oil compounds and water vapor by nebulizer on the thermal efficiency and production of pollutants in gas emissions of natural gas diffusion flame is studied. The Nebulizer device creates micron incisions of injected liquid and, due to the reduced injection particle diameter, existing highly turbulent outflow and proper mixing of oil and water vapor compounds with gas and air inlet to the burner, effectiveness of the injection increases to enhance efficiency and reduce pollutants. In the experimental setup, the injection of 1 wt.% of oil compounds into the natural gas flame by a nebulizer improves thermal efficiency by 2.5%, decreases the temperature of the exhaust gases from the chimney by 12%, and also X NO pollutants by 13%, and increases carbon monoxide pollutant by 6%. Also, the injection of 2 wt.% of water drops as well as 1 wt.% of oil...
This paper presents using density functional method to study nitrogen monoxide (NO) molecule phys... more This paper presents using density functional method to study nitrogen monoxide (NO) molecule physisorption with various concentrations on armchair graphene nanoribbon (GNR). We calculate the physical and electronic parameters of the GNR after nitrogen monoxide molecules adsorption. The Green’s function method is used to obtain the electronic properties and electrical current through the ribbon. The GNR is considered as a channel of a back-gated field effect transistor (FET) to study the sensing properties of a graphene nanoribbon field effect (GNR-FET) sensor. Results show that the GNR is a suitable sensing layer for NO detection with different concentrations. Also, the current in the channel increases when NO molecules density is increased. To improve the sensitivity of the sensor, we apply a gate voltage to change the Fermi level of the channel. Obtained results prove that by applying back gate voltage to the channel of the sensor, the current and sensitivity of the sensor are imp...
In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematic... more In recent days, artificial neural network (ANN) is seen as a potential tool to perform mathematical modeling and prediction. In this analysis, the Levenberg–Marquardt backpropagation training algorithm is used to map the actual and the predicted value with the tansig activation function. The ANN model is developed to predict the engine performance and emission parameters for varying intake biogas–air mixture temperatures ranging from 55 ± 5 to 85 ± 5 °C under various load conditions. Around 70% of the total experimental data has been used for training, 15% for validation, and 15% for testing. The findings show higher coefficient of correlation (R, R2 and adjusted R2 values are in the range of 0.96–0.99) and lower mean square error (MSE = 0.0003515–0.00544501) for the developed ANN models. This study proves that ANN is an excellent tool for determining and optimizing the performance and emission parameters of compression ignition engines fuelled with alternative gaseous fuels.
Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, the... more Because of large cold storage capacity and suitable freezing temperature of hydrate slurries, these materials could be used as a medium to store the cold energy in air conditioning systems. Semiclathrate hydrates of tetra n-butylammonium bromide (TBAB) are favorable phase change materials (PCMs), due to their moderate hydrate formation conditions. The kinetics of carbon dioxide - TBAB semiclathrate hydrate formation in presence and absence of tween 80 as a non-anionic surfactant is investigated in this research. The experiments were performed in a 169 cm3 stirred batch reactor at initial pressure of 3.2 MPa and isothermal condition of 276.15 K. Aqueous solutions of TBAB with concentrations of 0–15 wt% in presence and absence of tween 80 with concentrations of 500 and 1500 ppm are tested. The results revealed that utilization of TBAB with concentrations of 5–15 wt%, inhibits the kinetics of formed hydrates. By increasing the concentration of TBAB the amount and rate of gas uptake and...
Clathrate hydrate is a new technology to store the cold energy in air conditioning systems. These... more Clathrate hydrate is a new technology to store the cold energy in air conditioning systems. These compounds offer a high cold storage density. The phase change temperature of clathrate hydrates is more than water. On the other hand, these compounds offer better heat transfer properties and improved cyclic stability, compared to eutectic salts. These appropriate properties of clathrate hydrates made these compounds as promising potential for cold storage air conditioning systems. In this study, we investigated the refrigerant hydrate formation as a potential to store the cold energy. The equilibrium data reported by researchers are collected and the effect of various additives on their phase equilibria are investigated. A comparison between the dissociation pressure of hydrate formed in presence of some refrigerant are undertaken. Finally, the various methods of hydrate-based refrigeration systems reported in literature are collected along with their advantages and drawbacks.
The present article deals with the computational fluid dynamics (CFD) investigation of flow and h... more The present article deals with the computational fluid dynamics (CFD) investigation of flow and heat transfer of a [C2mim][CH3SO3]/Al 2 O 3 ionanofluid in one conventional tube and two different grooved tubes. The flow is considered to be single-phase and laminar (500 < Re < 2000), and the range of nanoparticle concentration is between 0.05 and 2 %. For properties of the ionanofluid, experimental data available in the literature have been used. The results of relative heat transfer coefficient, pumping power, and field synergy are presented for the three different tubes at various Reynolds numbers and ionanofluid concentrations. It is found that the effect of grooves is more pronounced at low concentrations. Moreover, the heat transfer coefficient and pumping power rise by increasing the concentration. Adding the nanoparticles has a greater impact on the heat transfer at lower Reynolds numbers. The pumping power is intensified by the Re increment. More uniform temperature and velocity distributions are achieved because of the more severe flow mixing induced by the grooves. Both the greatest heat transfer coefficient and the highest pumping power occur for the tube having the spirally corrugated grooves. The results show that the heat transfer varies by changing the geometry. At a volume concentration of 0.05 % and Re = 500, the heat transfer coefficient increases by 15.54 % in the tube with the spirally corrugated grooves compared to the conventional tube.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2011
In the present study, the applicability of widely used evaporation models (Dalton approach-based ... more In the present study, the applicability of widely used evaporation models (Dalton approach-based correlations) is experimentally investigated for natural, forced, and combined convection regimes. A series of experimental measurements are carried out over a wide range of water temperatures and air velocities for 0:01 Gr=Re 2 100 in a heated rectangular pool. The investigations show that the evaporation rate strongly depends on the convection regime's Gr/Re 2 value. The results show that the evaporation rate increases with the difference in vapour pressures over both forced convection (0:01 Gr=Re 2 0:1) and turbulent mixed convection regimes (0:15 Gr=Re 2 25). However, the escalation rate of evaporation decreases with Gr/Re 2 in the forced convection regime whereas in the turbulent mixed convection it increases. In addition, over the range of the free convection regime (Gr=Re 2 ! 25), the evaporation rate is affected not only by the vapour pressure difference but also by the density variation. A dimensionless correlation using the experimental data of all convection regimes (0:01 Gr=Re 2 100) is proposed to cover different water surface geometries and airflow conditions.
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