... Pipe-flow heat transfer in decaying swirl flow has been investigated by Ivanova [4], using ro... more ... Pipe-flow heat transfer in decaying swirl flow has been investigated by Ivanova [4], using rotating axial vanes to generate swirl, Blackwelder and Kreith [5], and Klepper [6], who employed twisted tapes to obtain decaying swirl flow. ...
In this study, polyurethane nanocapsules containing phase change material were synthesized by int... more In this study, polyurethane nanocapsules containing phase change material were synthesized by interfacial polycondensation polymerization method. Toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) were chosen as monomers. n-Nonadecane was employed as a core material. The properties of nanocapsules were characterized by DSC, FT-IR, and SEM. The results show that the nanocapsules were synthesized successfully and that the phase change temperature was about 29.6 °C, and the latent heat of fusion was about 82 Jg−1. The particle size was found to range from 100 to 340 nm.
International Journal of Thermal Sciences, Mar 1, 2011
Abstract The pressure drop and friction factor for the flow distilled water in microtubes with th... more Abstract The pressure drop and friction factor for the flow distilled water in microtubes with the diameters ranging from 0.20 mm to 0.589 mm were investigated experimentally. The experiments were carried out in the Reynolds number range of approximately 100–10000 and the length-to-diameter ratios (L/d) in the range of 16–265. It was observed that two different mechanisms of transition from laminar to turbulent flow occurred as smooth and abrupt. The pressure drop and friction factor values agreed with the values of classical channel flow theory. The L/d ratio had an important effect on the apparent friction factor in case of L/d
Journal of Environmental Chemical Engineering, 2021
Abstract In the present study, bipolar membrane electrodialysis (BMED) process was employed as an... more Abstract In the present study, bipolar membrane electrodialysis (BMED) process was employed as an alternative separation method to the distillation unit in the Solvay process for the synthetic soda ash production. The applicability of BMED was investigated by evaluating the effects of system parameters on process performance. Desalination ratio, salt based acid and base conversion ratio, flux, product purity, and energy consumption were defined as the process performance criteria for the BMED systems. Initial salt concentration, applied current and voltage, and initial acid and base concentrations were chosen as system parameters. The results of the study revealed that current/voltage and initial salt concentration are the most effective factors affecting all performance criteria. When all system parameters were considered, BMED provides the desalination ratio in between 90% and 98%, the acid and base conversion ratio of salt in between 60% and 80%, and the energy consumption in the range of 1.54–2.33 kWh/kg acid. Furthermore, the desalinated water can be reused as process water and the distillation unit waste problem can be resolved by the utilization of BMED system.
The heat transfer and pressure drop characteristics for the flow of water, which is base fluid, a... more The heat transfer and pressure drop characteristics for the flow of water, which is base fluid, and nanoencapsulated n-nonadecane based nanofluids in a double pipe heat exchanger were investigated. The results showed that no improvement in overall heat transfer coefficient was observed for the nanofluids containing 0.42% and 0.84% solid volume ratios with reference to the base fluid, while an improvement of about 10% was obtained for the nanofluids containing 1.68% solid volume ratio. It was found that the friction factors for the nanofluids exhibited a slight increase reference to the base fluid. A performance analysis based on constant pumping power was also performed.
International Journal of Environmental Science and Technology
The distillation waste (DW) is the biggest handicap of soda ash production with the Solvay proces... more The distillation waste (DW) is the biggest handicap of soda ash production with the Solvay process. The DW mainly consists of CaCl2 and NaCl, and especially the recent studies clearly show the damage it causes to the environment. With the aim to develop an alternative to the distillation unit in Solvay process, an experimental work was performed to investigate the effect of the working parameters on the different performance criteria for the production of NaOH+NH3.H2O mixture and HCI from simulated salt mixture of NaCI and NH4CI by bipolar membrane electrodialysis, and on the determination of the optimum working conditions. The performance criteria were taken as the acid and base concentrations, product-based salt conversion, product-based flux, energy consumption in the electrodialysis cell, desalination, and impurities in the products. The working parameters were chosen as the initial salt concentration, initial acid and base concentrations, initial acid and base volumes, current density, amount of impurity in product, and anolyte and catholyte concentrations. The experimental design and the search for the optimum working conditions for the performance criteria were performed by the Taguchi-based-multi-criteria decision-making method. Under optimum conditions, the products of 4.04 M HCl with 93.5% purity and 3.66 M NaOH + NH3.H2O with 98.7% purity (on dry basis), and 99.8% desalination were obtained.
Mass transfer measurements at both the inner and outer walls in decaying swirl flow in an annular... more Mass transfer measurements at both the inner and outer walls in decaying swirl flow in an annular duct have been carried out using the electrochemical limiting diffusion current technique. Swirl was generated using axial guide-vanes with vane angles between 15–67° to the duct axis. Pressure measurements at the outer wall were also made to enable estimation of the energy cost of mass transfer enhancement. Overall correlation of mass transfer at the outer wall for a representative length of test section in terms of the energy required to impart swirl to the flow can be expressed as Sh Sc -1/3 = 0.0251 (1 + tan θ w )-0.18 X 0.316 for the Reynolds number range 3000– 50000, where θ w is the vane angle at the wall and X is an energy dissipation parameter.
In this study, adsorption of Cu +2 ions from aqueous solution onto apricot stone shell as investi... more In this study, adsorption of Cu +2 ions from aqueous solution onto apricot stone shell as investigated. First the physicaland chemical characterization of apricot shell was performed, and then the effect of some working conditions on bisorbtion yield was investigated. The fit of the equilibrium results to the adsorption isotherms of Langmuir, Freundlichand Dubinin–Radushkevich (D–R) to data was examined, and it was determined that the best fitted model is Langmuir isotherm.
International Communications in Heat and Mass Transfer, 2009
This paper describes the pressure drop and local mass transfer in a rectangular microchannel havi... more This paper describes the pressure drop and local mass transfer in a rectangular microchannel having a width of 3.70 mm, height of 0.107 mm and length of 35 mm. The pressure measurements were carried out with distilled water as working fluid at Reynolds numbers in the range of 100–845, while mass transfer measurements with a chemical solution at Reynolds numbers in the range of 18–552 by using the electrochemical limiting diffusion current technique (ELDCT). Experimental friction factors were slightly higher than those calculated by theoretical correlation. The Sherwood number correlation was also obtained.
International Journal of Heat and Mass Transfer, 1997
ABSTRACT This paper describes an investigation of mass transfer to local electrodes at the wall a... more ABSTRACT This paper describes an investigation of mass transfer to local electrodes at the wall and wall friction factor behaviour in decaying swirl flow in a circular duct generated by short helical swirl generators. Five swirl generators with angles between 15–70° to duct axis were employed. The experiments were carried out in a Reynolds number range 8900-27 000 and at a Schmidt number of 1692. The axial distribution of the mass transfer to a circular electrode at the wall were measured using an electrochemical technique and the friction factors at the wall were calculated. Flow visualization experiments showed that no circulation nor dead zone occurs in the system. The local mass transfer data were correlated in the form of Shx = 0.0490 Rex0.817 (1+tan θ0)0.508, , for the whole range of swirl generator angles and the following correlations were developed f = 0.2517 Rex−0.263 (1 + tan θ0)0.880 and f = 39.810 Rex−0.642 (1 + tan θ0)0.746 for local friction factor for swirlers of 15–45° and 60 and 70°, respectively.
An experimental work was performed to investigate the usability of 8 metallic alloys with differe... more An experimental work was performed to investigate the usability of 8 metallic alloys with different composition in electrochemical limiting diffusion current technique employing the cathodic reduction of ferricyanide. All the alloys exhibited a limiting current plateau region in their voltage–current behaviour, but not all gave a wide and smooth plateau, except one with almost pure Ni. With the alloys of including more than 50% Ni, as Ni ratio of the metal increased, smoother and wider plateau was attained, and the electrode containing 99% Ni gave the smoothest plateau. The other alloys tested can only be used as electrode in the limiting diffusion current technique in low flow velocities in which the transfer of the active ion to the electrode surface is as slow as that the mass transfer controls the rate of system.
AbstractThe purpose of this study was to offer an alternative new eco-friendly and easily impleme... more AbstractThe purpose of this study was to offer an alternative new eco-friendly and easily implemented process for the production of hydrofluoric acid and sodium hydroxide. The production of hydrofluoric acid and sodium hydroxide from sodium fluoride was carried out by bipolar membranes electrodialysis. The process feasibility was tested using a laboratory electrodialysis cell. The behavior of the process was investigated for 0.05, 0.025 M concentration and 5, 7.5, 10 V potential. In conclusion, the current efficiencies were obtained up to a value of 98.51 at the applied potential of 10 V and 0.05 M, and the purities were found to be 99.7% and as 99.1% for hydrofluoric acid and sodium hydroxide, respectively. These high purities of acid and base were obtained without any harmful waste material or side product. When in terms of both production technique and environmental impact were compared to hydrofluoric acid production by the reaction of acid-grade fluorspar (CaF2) with sulfuric acid (H2SO4) and sodium ...
... Pipe-flow heat transfer in decaying swirl flow has been investigated by Ivanova [4], using ro... more ... Pipe-flow heat transfer in decaying swirl flow has been investigated by Ivanova [4], using rotating axial vanes to generate swirl, Blackwelder and Kreith [5], and Klepper [6], who employed twisted tapes to obtain decaying swirl flow. ...
In this study, polyurethane nanocapsules containing phase change material were synthesized by int... more In this study, polyurethane nanocapsules containing phase change material were synthesized by interfacial polycondensation polymerization method. Toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) were chosen as monomers. n-Nonadecane was employed as a core material. The properties of nanocapsules were characterized by DSC, FT-IR, and SEM. The results show that the nanocapsules were synthesized successfully and that the phase change temperature was about 29.6 °C, and the latent heat of fusion was about 82 Jg−1. The particle size was found to range from 100 to 340 nm.
International Journal of Thermal Sciences, Mar 1, 2011
Abstract The pressure drop and friction factor for the flow distilled water in microtubes with th... more Abstract The pressure drop and friction factor for the flow distilled water in microtubes with the diameters ranging from 0.20 mm to 0.589 mm were investigated experimentally. The experiments were carried out in the Reynolds number range of approximately 100–10000 and the length-to-diameter ratios (L/d) in the range of 16–265. It was observed that two different mechanisms of transition from laminar to turbulent flow occurred as smooth and abrupt. The pressure drop and friction factor values agreed with the values of classical channel flow theory. The L/d ratio had an important effect on the apparent friction factor in case of L/d
Journal of Environmental Chemical Engineering, 2021
Abstract In the present study, bipolar membrane electrodialysis (BMED) process was employed as an... more Abstract In the present study, bipolar membrane electrodialysis (BMED) process was employed as an alternative separation method to the distillation unit in the Solvay process for the synthetic soda ash production. The applicability of BMED was investigated by evaluating the effects of system parameters on process performance. Desalination ratio, salt based acid and base conversion ratio, flux, product purity, and energy consumption were defined as the process performance criteria for the BMED systems. Initial salt concentration, applied current and voltage, and initial acid and base concentrations were chosen as system parameters. The results of the study revealed that current/voltage and initial salt concentration are the most effective factors affecting all performance criteria. When all system parameters were considered, BMED provides the desalination ratio in between 90% and 98%, the acid and base conversion ratio of salt in between 60% and 80%, and the energy consumption in the range of 1.54–2.33 kWh/kg acid. Furthermore, the desalinated water can be reused as process water and the distillation unit waste problem can be resolved by the utilization of BMED system.
The heat transfer and pressure drop characteristics for the flow of water, which is base fluid, a... more The heat transfer and pressure drop characteristics for the flow of water, which is base fluid, and nanoencapsulated n-nonadecane based nanofluids in a double pipe heat exchanger were investigated. The results showed that no improvement in overall heat transfer coefficient was observed for the nanofluids containing 0.42% and 0.84% solid volume ratios with reference to the base fluid, while an improvement of about 10% was obtained for the nanofluids containing 1.68% solid volume ratio. It was found that the friction factors for the nanofluids exhibited a slight increase reference to the base fluid. A performance analysis based on constant pumping power was also performed.
International Journal of Environmental Science and Technology
The distillation waste (DW) is the biggest handicap of soda ash production with the Solvay proces... more The distillation waste (DW) is the biggest handicap of soda ash production with the Solvay process. The DW mainly consists of CaCl2 and NaCl, and especially the recent studies clearly show the damage it causes to the environment. With the aim to develop an alternative to the distillation unit in Solvay process, an experimental work was performed to investigate the effect of the working parameters on the different performance criteria for the production of NaOH+NH3.H2O mixture and HCI from simulated salt mixture of NaCI and NH4CI by bipolar membrane electrodialysis, and on the determination of the optimum working conditions. The performance criteria were taken as the acid and base concentrations, product-based salt conversion, product-based flux, energy consumption in the electrodialysis cell, desalination, and impurities in the products. The working parameters were chosen as the initial salt concentration, initial acid and base concentrations, initial acid and base volumes, current density, amount of impurity in product, and anolyte and catholyte concentrations. The experimental design and the search for the optimum working conditions for the performance criteria were performed by the Taguchi-based-multi-criteria decision-making method. Under optimum conditions, the products of 4.04 M HCl with 93.5% purity and 3.66 M NaOH + NH3.H2O with 98.7% purity (on dry basis), and 99.8% desalination were obtained.
Mass transfer measurements at both the inner and outer walls in decaying swirl flow in an annular... more Mass transfer measurements at both the inner and outer walls in decaying swirl flow in an annular duct have been carried out using the electrochemical limiting diffusion current technique. Swirl was generated using axial guide-vanes with vane angles between 15–67° to the duct axis. Pressure measurements at the outer wall were also made to enable estimation of the energy cost of mass transfer enhancement. Overall correlation of mass transfer at the outer wall for a representative length of test section in terms of the energy required to impart swirl to the flow can be expressed as Sh Sc -1/3 = 0.0251 (1 + tan θ w )-0.18 X 0.316 for the Reynolds number range 3000– 50000, where θ w is the vane angle at the wall and X is an energy dissipation parameter.
In this study, adsorption of Cu +2 ions from aqueous solution onto apricot stone shell as investi... more In this study, adsorption of Cu +2 ions from aqueous solution onto apricot stone shell as investigated. First the physicaland chemical characterization of apricot shell was performed, and then the effect of some working conditions on bisorbtion yield was investigated. The fit of the equilibrium results to the adsorption isotherms of Langmuir, Freundlichand Dubinin–Radushkevich (D–R) to data was examined, and it was determined that the best fitted model is Langmuir isotherm.
International Communications in Heat and Mass Transfer, 2009
This paper describes the pressure drop and local mass transfer in a rectangular microchannel havi... more This paper describes the pressure drop and local mass transfer in a rectangular microchannel having a width of 3.70 mm, height of 0.107 mm and length of 35 mm. The pressure measurements were carried out with distilled water as working fluid at Reynolds numbers in the range of 100–845, while mass transfer measurements with a chemical solution at Reynolds numbers in the range of 18–552 by using the electrochemical limiting diffusion current technique (ELDCT). Experimental friction factors were slightly higher than those calculated by theoretical correlation. The Sherwood number correlation was also obtained.
International Journal of Heat and Mass Transfer, 1997
ABSTRACT This paper describes an investigation of mass transfer to local electrodes at the wall a... more ABSTRACT This paper describes an investigation of mass transfer to local electrodes at the wall and wall friction factor behaviour in decaying swirl flow in a circular duct generated by short helical swirl generators. Five swirl generators with angles between 15–70° to duct axis were employed. The experiments were carried out in a Reynolds number range 8900-27 000 and at a Schmidt number of 1692. The axial distribution of the mass transfer to a circular electrode at the wall were measured using an electrochemical technique and the friction factors at the wall were calculated. Flow visualization experiments showed that no circulation nor dead zone occurs in the system. The local mass transfer data were correlated in the form of Shx = 0.0490 Rex0.817 (1+tan θ0)0.508, , for the whole range of swirl generator angles and the following correlations were developed f = 0.2517 Rex−0.263 (1 + tan θ0)0.880 and f = 39.810 Rex−0.642 (1 + tan θ0)0.746 for local friction factor for swirlers of 15–45° and 60 and 70°, respectively.
An experimental work was performed to investigate the usability of 8 metallic alloys with differe... more An experimental work was performed to investigate the usability of 8 metallic alloys with different composition in electrochemical limiting diffusion current technique employing the cathodic reduction of ferricyanide. All the alloys exhibited a limiting current plateau region in their voltage–current behaviour, but not all gave a wide and smooth plateau, except one with almost pure Ni. With the alloys of including more than 50% Ni, as Ni ratio of the metal increased, smoother and wider plateau was attained, and the electrode containing 99% Ni gave the smoothest plateau. The other alloys tested can only be used as electrode in the limiting diffusion current technique in low flow velocities in which the transfer of the active ion to the electrode surface is as slow as that the mass transfer controls the rate of system.
AbstractThe purpose of this study was to offer an alternative new eco-friendly and easily impleme... more AbstractThe purpose of this study was to offer an alternative new eco-friendly and easily implemented process for the production of hydrofluoric acid and sodium hydroxide. The production of hydrofluoric acid and sodium hydroxide from sodium fluoride was carried out by bipolar membranes electrodialysis. The process feasibility was tested using a laboratory electrodialysis cell. The behavior of the process was investigated for 0.05, 0.025 M concentration and 5, 7.5, 10 V potential. In conclusion, the current efficiencies were obtained up to a value of 98.51 at the applied potential of 10 V and 0.05 M, and the purities were found to be 99.7% and as 99.1% for hydrofluoric acid and sodium hydroxide, respectively. These high purities of acid and base were obtained without any harmful waste material or side product. When in terms of both production technique and environmental impact were compared to hydrofluoric acid production by the reaction of acid-grade fluorspar (CaF2) with sulfuric acid (H2SO4) and sodium ...
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