mansoor inayat - Academia.edu (original) (raw)
Papers by mansoor inayat
International Journal of Heat and Mass Transfer/International journal of heat and mass transfer, Jun 1, 2024
Nuclear Science and Engineering, Jan 23, 2023
Epj Web of Conferences, 2013
A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separa... more A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separated by slugs of pure liquid. This type of flow regime is well suited for solid catalyzed gas-liquid reactors in which the reaction efficiency is a strong function of axial dispersion in the regions of pure liquid. This paper presents an experimental study of liquid phase axial dispersion in a Taylor bubble flow developed in a horizontal tube using high speed photography and radiotracer residence time distribution (RTD) analysis. A parametric dependence of axial dispersion on average volume fraction of gas phase was also investigated by varying the relative volumetric flow rates of the two phases. 137m Ba produced from a 137 Cs/ 137m Ba radionuclide generator was used as radiotracer and measurements were made using the NaI(Tl) scintillation detectors. Validation of 137m Ba in the form of barium chloride as aqueous phase radiotracer was also carried out. Axial Dispersion Model (ADM) was used to simulate the hydrodynamics of the system and the results of the experiment are presented. It was observed that the system is characterized by very high values of Peclet Number (Pe∼10 2) which reveals an approaching plug type flow. The experimental and model estimated values of mean residence times were observed in agreement with each other.
Energies, Mar 31, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Applied Radiation and Isotopes, Dec 1, 2008
Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range ... more Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range of dispersed and continuous phase superficial velocities in a pulsed sieve plate extraction column using radiotracer residence time distribution (RTD) analysis. Axial dispersion model (ADM) was used to simulate the hydrodynamics of the system. It has been observed that increase in dispersed phase superficial velocity results in a decrease in its axial dispersion and increase in its slip velocity while its holdup increases till a maximum asymptotic value is achieved. An increase in superficial velocity of continuous phase increases the axial dispersion and holdup of dispersed phase until a maximum value is obtained, while slip velocity of dispersed phase is found to decrease in the beginning and then it increases with increase in superficial velocity of continuous phase.
Applied Radiation and Isotopes, Jul 1, 2009
Separation and Purification Technology, Jun 18, 2010
A Computational Fluid Dynamics (CFD) based model of a two-phase countercurrent pulsed sieve plate... more A Computational Fluid Dynamics (CFD) based model of a two-phase countercurrent pulsed sieve plate extraction column has been developed. EulerEuler multiphase flow model and standard k turbulence model for multiphase flow were used. Sieve plates in the column were ...
International Journal of Heat and Mass Transfer, May 1, 2014
ABSTRACT The phenomenon of direct-contact condensation is very important with respect to several ... more ABSTRACT The phenomenon of direct-contact condensation is very important with respect to several industrial applications, such as steam jet pumps, direct-contact heat exchangers and nuclear reactor cooling systems. The direct and quick transfer of heat, mass and momentum across the steam–water interface makes the physics of direct-contact condensation very complex. In this work the phenomenon of direct-contact condensation, in steam jet pump, has been studied experimentally and computationally. The length of the mixing section has been varied to study its effect on the phenomenon occurring there. The experimental and CFD results obtained in this study match closely with each other and indicate towards an important process known as interface vibration process in direct-contact condensation of steam jet pump. It was found that this process has a strong dependence on the length of mixing section and plays an important role in producing high suction at the water nozzle outlet. As a result we get efficient transfer of heat, mass and momentum across the steam–water interface in steam jet pump.
International Journal of Multiphase Flow, Dec 1, 2011
Steam jet pump is the best choice for pumping radioactive and hazardous liquids because it has no... more Steam jet pump is the best choice for pumping radioactive and hazardous liquids because it has no moving parts and so no maintenance. However, the physics involved is highly complicated because of the mass, momentum and energy transfer between the phases involved. In this study the characteristics of SJP are studied both experimentally and numerically to pump water using saturated steam. In the experimental study the static pressure, temperature along the length of the steam jet pump and the steam and water flow rates are recorded. The three dimensional numerical study is carried out using the Eulerian two-phase flow model of Fluent 6.3 software and the direct-contact condensation model developed previously. The experimental and CFD results, of axial static pressure and temperature, match closely with each other. The mass ratio and suction lift are calculated from experimental data and it is observed that the mass ratio varies from 10 to 62 and the maximum value of suction lift is 2.12 m under the conditions of the experiment.
International Journal of Heat and Mass Transfer, Mar 1, 2013
Steam jet pump (SJP) is a simple mechanical device and may be regarded as the most suitable pump ... more Steam jet pump (SJP) is a simple mechanical device and may be regarded as the most suitable pump for pumping hazardous liquids because of its mechanical simplicity, no maintenance, simple control etc. In this study, an experimental setup of SJP was developed in which the mixing section was made transparent for flow visualization. The effect of the mixing section length on the transport process in SJP has been studied using three different lengths of the mixing section (110, 130 and 150 mm). Moreover experiments were performed to study the suction characteristics of SJP at various operating conditions. Better performance was observed in the SJP geometry with shorter length of the mixing section. A new concept of interface vibration process in direct-contact condensation (DCC) of SJP was introduced using the experimental results. An effort has been made to explain the process of DCC in SJP using the concept of interface vibration process. The performance characteristics of SJP have also been studied in the light of interface vibration process in DCC of SJP.
Chinese Journal of Chemical Engineering, Aug 1, 2010
The phenomenon of direct-contact condensation, used in steam driven jet injectors, nuclear reacto... more The phenomenon of direct-contact condensation, used in steam driven jet injectors, nuclear reactor emergency core cooling systems and direct-contact heat exchangers, was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in ...
Asia-Pacific Journal of Chemical Engineering, Apr 26, 2013
Overall liquid side volumetric mass transfer coefficient k L a was determined experimentally for ... more Overall liquid side volumetric mass transfer coefficient k L a was determined experimentally for cocurrent Taylor flow moving upwards in a glass tube of an internal diameter of 3 mm. Experiments were performed for physical absorption of oxygen in 20% aqueous solution of ethanol. Shadowgraph technique was deployed for precise measurements of bubble lengths and velocities. Experimental values of volumetric mass transfer coefficient k L a were evaluated by use of oxygen sensor and contributions of two possible mass transfer mechanisms: bubble to liquid slug and bubble to liquid film were discussed. Effects of various hydrodynamic parameters such as superficial velocity, length of bubble and slug, and so forth on k L a have also been presented. A correlation has been proposed for the estimation of k L a for a wide range of bubble to slug lengths ratio and superficial velocities of gas and liquids.
ABSTRACT Rectangular shaped sieve plate column was installed for study of transport parameters th... more ABSTRACT Rectangular shaped sieve plate column was installed for study of transport parameters through high speed photography and image analysis. Two Immiscible liquids consisting of the dispersed phase (water) and continuous phase (kerosene oil) were introduced in countercurrent operation. Experiments were performed for dispersed and continuous phase superficial velocities 0.16-0.44 cm/sec and 0.37-0.47 cm/sec respectively, pulsation frequency 0.95 -1.72 rev/sec and pulsation amplitude 1cm. Upon increasing the superficial velocity of dispersed phase, its void fraction increases up to its asymptotic value and droplet velocity increase while the droplet size decreases. Upon increasing the pulsation frequency, its void fraction increases while the droplet size and droplet velocity decreases. A Computational Multi Fluid Dynamics simulation has been carried out in order to verify the experimental results using the FLUENT. The CMFD calculations for void fraction have been compared with the experimental results which have shown a maximum deviation of 2-3%.
Chemical Papers, Aug 11, 2022
Epj Web of Conferences, 2013
The present investigations are focused to study the hydrodynamic characteristics of continuous ph... more The present investigations are focused to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column using 68 Ga in the form of gallium chloride from an industrial radionuclide generator (68 Ge/ 68 Ga). Labeling of water with the subject radiotracer in water-kerosene environment was evaluated. Experiments for Residence Time Distribution (RTD) analysis were carried out for a range of dispersed phase superficial velocities in a liquid-liquid extraction pulsed sieve plate column operating in the emulsion regime with water as continuous and kerosene as dispersed phase. Axial Dispersion Model (ADM) was used to simulate the hydrodynamic characteristics of continuous phase. It has been observed that the axial mixing in the continuous phase decreases and slip velocity increases with increase in superficial velocity of dispersed phase while the holdup of continuous phase was found to decrease with increase in superficial velocity of dispersed phase. ADM with open-open boundary condition was found to be a suitable model for the subject system.
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy
Reduction in ambient pressure within the containment of a light water reactor in the event of a h... more Reduction in ambient pressure within the containment of a light water reactor in the event of a hypothetical Loss of Coolant Accident (LOCA) is crucial for containment integrity. This article introduces the distinct concept of a Passive Containment Cooling System (PCCS). In the proposed PCCS concept, the containment is divided into two compartments with appropriate volumes. An external heat exchanger is connected between the two compartments of the containment for heat transfer and pressure reduction in the case of LOCA. This concept has unique characteristics and provides many advantages over previous designs. A RELAP5 model was developed to perform thermal-hydraulic analysis of the proposed PCCS concept. The performance of the PCCS after its deployment on a small reactor (998.6 MWth) has been assessed under various conditions following LOCA. The results indicate that partitioning of the containment creates a differential pressure that acts as a driving force for flow through the P...
2022 19th International Bhurban Conference on Applied Sciences and Technology (IBCAST)
Nuclear Science and Engineering
International Journal of Heat and Mass Transfer/International journal of heat and mass transfer, Jun 1, 2024
Nuclear Science and Engineering, Jan 23, 2023
Epj Web of Conferences, 2013
A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separa... more A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separated by slugs of pure liquid. This type of flow regime is well suited for solid catalyzed gas-liquid reactors in which the reaction efficiency is a strong function of axial dispersion in the regions of pure liquid. This paper presents an experimental study of liquid phase axial dispersion in a Taylor bubble flow developed in a horizontal tube using high speed photography and radiotracer residence time distribution (RTD) analysis. A parametric dependence of axial dispersion on average volume fraction of gas phase was also investigated by varying the relative volumetric flow rates of the two phases. 137m Ba produced from a 137 Cs/ 137m Ba radionuclide generator was used as radiotracer and measurements were made using the NaI(Tl) scintillation detectors. Validation of 137m Ba in the form of barium chloride as aqueous phase radiotracer was also carried out. Axial Dispersion Model (ADM) was used to simulate the hydrodynamics of the system and the results of the experiment are presented. It was observed that the system is characterized by very high values of Peclet Number (Pe∼10 2) which reveals an approaching plug type flow. The experimental and model estimated values of mean residence times were observed in agreement with each other.
Energies, Mar 31, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Applied Radiation and Isotopes, Dec 1, 2008
Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range ... more Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range of dispersed and continuous phase superficial velocities in a pulsed sieve plate extraction column using radiotracer residence time distribution (RTD) analysis. Axial dispersion model (ADM) was used to simulate the hydrodynamics of the system. It has been observed that increase in dispersed phase superficial velocity results in a decrease in its axial dispersion and increase in its slip velocity while its holdup increases till a maximum asymptotic value is achieved. An increase in superficial velocity of continuous phase increases the axial dispersion and holdup of dispersed phase until a maximum value is obtained, while slip velocity of dispersed phase is found to decrease in the beginning and then it increases with increase in superficial velocity of continuous phase.
Applied Radiation and Isotopes, Jul 1, 2009
Separation and Purification Technology, Jun 18, 2010
A Computational Fluid Dynamics (CFD) based model of a two-phase countercurrent pulsed sieve plate... more A Computational Fluid Dynamics (CFD) based model of a two-phase countercurrent pulsed sieve plate extraction column has been developed. EulerEuler multiphase flow model and standard k turbulence model for multiphase flow were used. Sieve plates in the column were ...
International Journal of Heat and Mass Transfer, May 1, 2014
ABSTRACT The phenomenon of direct-contact condensation is very important with respect to several ... more ABSTRACT The phenomenon of direct-contact condensation is very important with respect to several industrial applications, such as steam jet pumps, direct-contact heat exchangers and nuclear reactor cooling systems. The direct and quick transfer of heat, mass and momentum across the steam–water interface makes the physics of direct-contact condensation very complex. In this work the phenomenon of direct-contact condensation, in steam jet pump, has been studied experimentally and computationally. The length of the mixing section has been varied to study its effect on the phenomenon occurring there. The experimental and CFD results obtained in this study match closely with each other and indicate towards an important process known as interface vibration process in direct-contact condensation of steam jet pump. It was found that this process has a strong dependence on the length of mixing section and plays an important role in producing high suction at the water nozzle outlet. As a result we get efficient transfer of heat, mass and momentum across the steam–water interface in steam jet pump.
International Journal of Multiphase Flow, Dec 1, 2011
Steam jet pump is the best choice for pumping radioactive and hazardous liquids because it has no... more Steam jet pump is the best choice for pumping radioactive and hazardous liquids because it has no moving parts and so no maintenance. However, the physics involved is highly complicated because of the mass, momentum and energy transfer between the phases involved. In this study the characteristics of SJP are studied both experimentally and numerically to pump water using saturated steam. In the experimental study the static pressure, temperature along the length of the steam jet pump and the steam and water flow rates are recorded. The three dimensional numerical study is carried out using the Eulerian two-phase flow model of Fluent 6.3 software and the direct-contact condensation model developed previously. The experimental and CFD results, of axial static pressure and temperature, match closely with each other. The mass ratio and suction lift are calculated from experimental data and it is observed that the mass ratio varies from 10 to 62 and the maximum value of suction lift is 2.12 m under the conditions of the experiment.
International Journal of Heat and Mass Transfer, Mar 1, 2013
Steam jet pump (SJP) is a simple mechanical device and may be regarded as the most suitable pump ... more Steam jet pump (SJP) is a simple mechanical device and may be regarded as the most suitable pump for pumping hazardous liquids because of its mechanical simplicity, no maintenance, simple control etc. In this study, an experimental setup of SJP was developed in which the mixing section was made transparent for flow visualization. The effect of the mixing section length on the transport process in SJP has been studied using three different lengths of the mixing section (110, 130 and 150 mm). Moreover experiments were performed to study the suction characteristics of SJP at various operating conditions. Better performance was observed in the SJP geometry with shorter length of the mixing section. A new concept of interface vibration process in direct-contact condensation (DCC) of SJP was introduced using the experimental results. An effort has been made to explain the process of DCC in SJP using the concept of interface vibration process. The performance characteristics of SJP have also been studied in the light of interface vibration process in DCC of SJP.
Chinese Journal of Chemical Engineering, Aug 1, 2010
The phenomenon of direct-contact condensation, used in steam driven jet injectors, nuclear reacto... more The phenomenon of direct-contact condensation, used in steam driven jet injectors, nuclear reactor emergency core cooling systems and direct-contact heat exchangers, was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in ...
Asia-Pacific Journal of Chemical Engineering, Apr 26, 2013
Overall liquid side volumetric mass transfer coefficient k L a was determined experimentally for ... more Overall liquid side volumetric mass transfer coefficient k L a was determined experimentally for cocurrent Taylor flow moving upwards in a glass tube of an internal diameter of 3 mm. Experiments were performed for physical absorption of oxygen in 20% aqueous solution of ethanol. Shadowgraph technique was deployed for precise measurements of bubble lengths and velocities. Experimental values of volumetric mass transfer coefficient k L a were evaluated by use of oxygen sensor and contributions of two possible mass transfer mechanisms: bubble to liquid slug and bubble to liquid film were discussed. Effects of various hydrodynamic parameters such as superficial velocity, length of bubble and slug, and so forth on k L a have also been presented. A correlation has been proposed for the estimation of k L a for a wide range of bubble to slug lengths ratio and superficial velocities of gas and liquids.
ABSTRACT Rectangular shaped sieve plate column was installed for study of transport parameters th... more ABSTRACT Rectangular shaped sieve plate column was installed for study of transport parameters through high speed photography and image analysis. Two Immiscible liquids consisting of the dispersed phase (water) and continuous phase (kerosene oil) were introduced in countercurrent operation. Experiments were performed for dispersed and continuous phase superficial velocities 0.16-0.44 cm/sec and 0.37-0.47 cm/sec respectively, pulsation frequency 0.95 -1.72 rev/sec and pulsation amplitude 1cm. Upon increasing the superficial velocity of dispersed phase, its void fraction increases up to its asymptotic value and droplet velocity increase while the droplet size decreases. Upon increasing the pulsation frequency, its void fraction increases while the droplet size and droplet velocity decreases. A Computational Multi Fluid Dynamics simulation has been carried out in order to verify the experimental results using the FLUENT. The CMFD calculations for void fraction have been compared with the experimental results which have shown a maximum deviation of 2-3%.
Chemical Papers, Aug 11, 2022
Epj Web of Conferences, 2013
The present investigations are focused to study the hydrodynamic characteristics of continuous ph... more The present investigations are focused to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column using 68 Ga in the form of gallium chloride from an industrial radionuclide generator (68 Ge/ 68 Ga). Labeling of water with the subject radiotracer in water-kerosene environment was evaluated. Experiments for Residence Time Distribution (RTD) analysis were carried out for a range of dispersed phase superficial velocities in a liquid-liquid extraction pulsed sieve plate column operating in the emulsion regime with water as continuous and kerosene as dispersed phase. Axial Dispersion Model (ADM) was used to simulate the hydrodynamic characteristics of continuous phase. It has been observed that the axial mixing in the continuous phase decreases and slip velocity increases with increase in superficial velocity of dispersed phase while the holdup of continuous phase was found to decrease with increase in superficial velocity of dispersed phase. ADM with open-open boundary condition was found to be a suitable model for the subject system.
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy
Reduction in ambient pressure within the containment of a light water reactor in the event of a h... more Reduction in ambient pressure within the containment of a light water reactor in the event of a hypothetical Loss of Coolant Accident (LOCA) is crucial for containment integrity. This article introduces the distinct concept of a Passive Containment Cooling System (PCCS). In the proposed PCCS concept, the containment is divided into two compartments with appropriate volumes. An external heat exchanger is connected between the two compartments of the containment for heat transfer and pressure reduction in the case of LOCA. This concept has unique characteristics and provides many advantages over previous designs. A RELAP5 model was developed to perform thermal-hydraulic analysis of the proposed PCCS concept. The performance of the PCCS after its deployment on a small reactor (998.6 MWth) has been assessed under various conditions following LOCA. The results indicate that partitioning of the containment creates a differential pressure that acts as a driving force for flow through the P...
2022 19th International Bhurban Conference on Applied Sciences and Technology (IBCAST)
Nuclear Science and Engineering