ABSTRACT A computational fluid dynamics (CFD) model of the pyrolysis of a Loy Yang low-rank coal ... more ABSTRACT A computational fluid dynamics (CFD) model of the pyrolysis of a Loy Yang low-rank coal in a pressurised drop tube furnace (pdtf) was undertaken evaluating Arrhenius reaction rate constants. The paper also presents predictions of an isothermal flow through the drop tube furnace. In this study, a pdtf reactor operated at pressures up to 15 bar and at a temperature of 1,173 K with particle heating rates of approximately 105 K s−1 was used. The CFD model consists of two geometrical sections; flow straightner and injector. The single reaction and two competing reaction models were employed for this numerical investigation of the pyrolysis process. The results are validated against the available experimental data in terms of velocity profiles for the drop tube furnace and the particle mass loss versus particle residence times. The isothermal flow results showed reasonable agreement with the available experimental data at different locations from the injector tip. The predicted results of both the single reaction and competing reaction modes showed slightly different results. In addition, several reaction rate constants were tested and validated against the available experimental data. The most accurate results were being Badzioch and Hawksley (Ind Eng Chem Process Des Dev 9:521–530, 1970) with a single reaction model and Ubhayakar et al. (Symp (Int) Combust 16:427–436, 1977) for two competing reactions. These numerical results can provide useful information towards future modelling of the behaviour of Loy Yang coal in a full scale tangentially-fired furnace.
IOP Conference Series: Materials Science and Engineering
Computational Fluid Dynamics CFD modeling study was carried out to investigate the effect of the ... more Computational Fluid Dynamics CFD modeling study was carried out to investigate the effect of the pin fins arrangements over the flat plate heat sink. The pin fins were adopted with in-line array form over the surface of the heat sink with different parameters. The CFD domain was designed by the use of ANSYS FLUENT 2019 R1 commercial software. The Reynolds Average Naiver Stoke RANS turbulent model was used in this study to show accurately capture the effect of alternating acceleration and deceleration and consequent variations in the pressure field. The heat sink is in a rectangular shape with a rib length of 100mm and100mm. This CFD investigation included a simulation of the proposed heat sink under the forced convection with Reynolds number range of 2166.67 ∼ 19500 and subjected heat flux of 1000W/m2. Pin fins diameters range were 3, 6 and 9mm while the fin lengths range were 5, 10 and 15mm under the same the heat flux and Reynolds number. The predicted results showed an augmentati...
This paper presents a three-dimensional numerical investigation of pulverized dry lignite in a 10... more This paper presents a three-dimensional numerical investigation of pulverized dry lignite in a 100 kW oxyfuel furnace. A computational fluid dynamics (CFD) code was used to model four different combustion scenarios. One air-fired combustion case and three oxy-fuel-fired cases, known as OF25 (25 vol. % O2 concentration), OF27 (27 vol. % O2 concentration), and OF29 (29 vol. % O2 concentration), were modelled. User-defined functions (UDFs) for the multistep reaction schemes were written and incorporated to the CFD code. Under oxy-fuel combustion, the appropriate mathematical models were implemented to calculate the flame temperature distributions and species concentrations (O2 and CO2). The multi-step chemical reaction schemes were used for the gas-phase and solid-phase coal particle reactions. In addition to the one-step (reference) reaction scheme, twostep and three-step reaction schemes were considered in this numerical study. Compared to the one-step and twostep reactions, the thre...
The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted t... more The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted to simulate the conventional solar heating system, multipurpose solar water heater (MPSWH), and multipurpose solar air heater (MPSAH). The commercial computational fluid dynamics (CFD), AVL Fire ver. 2009.2 was used to solve and investigate the temperature distributions in the absorber plate and riser tube of both solar water and air heater during summer and winter seasons. The RNG k - turbulence model was employed for this CFD study.  The present paper was to provide a good understanding of thermal performance for the solar collector at different operating conditions. The experimental setup and physical data of  Venkatesh, R. and Christraj, W. [15] were employed as geometric parameters and initial boundary conditions to model and to validate the predicted numerical values. Comparing to the values of temperatures for the conventional SWH and SAH, the predicted results of the MPSWH and t...
A computational fluid dynamics (CFD) modelling study is undertaken integrating the air-fired and ... more A computational fluid dynamics (CFD) modelling study is undertaken integrating the air-fired and oxy-fuel combustion cases for chemical reactions, radiative heat transfer, and gas compositions into a 3-D hybrid unstructured grid CFD code. A swirl injection system is used to achieve the flame stability of the turbulent non-premixed combustible gases. An Eddy Breakup (EBU) combustion model with appropriate empirical coefficients is employed for this study. Validation and comparison of both combustion cases with the experimental data, which conducted on a 100 kW facility unit, were made by comparing the temperature distribution levels and species concentration levels. The oxy-fuel combustion case showed that the flame is obviously concentrated in the central region, and it is not spread inside the furnace compared to the air-fired flame. The swirl effect is certainly used to enhance the turbulent mixing and to achieve the internal recirculation of flames. By switching to oxy-fuel fired...
In the present paper, the effect of the Net Positive Suction Head (NPSH) for the centrifugal pump... more In the present paper, the effect of the Net Positive Suction Head (NPSH) for the centrifugal pump in a simple pipeline system has been carried out eliminating water hammer. Both the experimental tests and numerical calculations were performed in this study to investigate the transient flow effects when the discharges change abruptly in the system. The phenomenon of transient flow is generally occurred when the sudden opening of the downstream valves are used in the pumping station or due to introducing additional parallel branches of pipelines that contain pumps. Experimentally, two operational tests with different NPSH were conducted to show the relations between the head (H) and discharge (Q). The results of these tests showed two different types of H-Q curves. The first test produced a flat H-Q curve when the water surface level in the suction tank was 4 m above the center line of the pump. While in the second test the operational case created a steep H-Q curve when the pump was ...
This paper was recommended for publication in revised form by Regional Editor Nader Javani. 1 Dep... more This paper was recommended for publication in revised form by Regional Editor Nader Javani. 1 Department of Mechanical Engineering, Al-Nahrain University, Baghdad, IRAQ 2 Pumps Engineering Department, Technical College of Al-Musaib, Al-Furat Al-Awsat Technical University, Kufa, IRAQ 3 University Politehnica of Bucharest, Faculty of Power Engineering, Bucharest, Romania. *E-mail address: drahmed955@eng.nahrainuniv.edu.iq Orc d ID: 0000-0003-1965-1412, 0000-0002-5809-4105, 0000-0002-4352-4299, 0000-0002-5809-4105. Manuscript Received 28 March 2020, Accepted 16 June 2020 TURBULENT HEAT TRANSFER FOR INTERNAL FLOW OF ETHYLENE GLYCOLAL2O3 NANOFLUID IN A SPIRAL GROOVED TUBE WITH TWISTED TAPE INSERTS
In this study, experimental investigations and exergy analysis on shell and helically coiled tube... more In this study, experimental investigations and exergy analysis on shell and helically coiled tube heat exchanger are carried out for free convection heat transfer. The measured data are totally optimised utilizing thermodynamics rules in which exergy study is performed to investigate the thermal performance of the helical system under different operating conditions. The experimental set-up of apparatus are designed and made for cold water and hot water as a working fluid of both the shell side and helical coil side, respectively. The effects of several parameters such as geometry and operational conditions on the exergy destruction and dimensionless exergy destruction are investigated. The counter flow direction is considered under the steady state flow condition, and the critical Reynolds number was more than 4000 in this study. The main objective of this work was to clarify the effect of the volume flow rates and inlet temperatures of hot water and cold water in the shell and helical coil on exergy efficiency and pressure drop. Results showed that the exergy destruction and dimensionless exergy destruction decrease with the increase of coil pitch and Dean number. In contrast, the exergy destruction and dimensionless exergy destruction are obviously increased with the hot water flow rates or cold water flow rates. These exergy characteristics are also augmented with the values of hot water inlet temperatures and cold water inlet temperatures. The pressure drop is considerably increased with the increase of Dean number and reduced with the increase of coil diameter. While, the exergy efficiency steadily increases with the decrease of the cold water flow rates and with the increase of Dean number.
ABSTRACT A computational fluid dynamics (CFD) model of the pyrolysis of a Loy Yang low-rank coal ... more ABSTRACT A computational fluid dynamics (CFD) model of the pyrolysis of a Loy Yang low-rank coal in a pressurised drop tube furnace (pdtf) was undertaken evaluating Arrhenius reaction rate constants. The paper also presents predictions of an isothermal flow through the drop tube furnace. In this study, a pdtf reactor operated at pressures up to 15 bar and at a temperature of 1,173 K with particle heating rates of approximately 105 K s−1 was used. The CFD model consists of two geometrical sections; flow straightner and injector. The single reaction and two competing reaction models were employed for this numerical investigation of the pyrolysis process. The results are validated against the available experimental data in terms of velocity profiles for the drop tube furnace and the particle mass loss versus particle residence times. The isothermal flow results showed reasonable agreement with the available experimental data at different locations from the injector tip. The predicted results of both the single reaction and competing reaction modes showed slightly different results. In addition, several reaction rate constants were tested and validated against the available experimental data. The most accurate results were being Badzioch and Hawksley (Ind Eng Chem Process Des Dev 9:521–530, 1970) with a single reaction model and Ubhayakar et al. (Symp (Int) Combust 16:427–436, 1977) for two competing reactions. These numerical results can provide useful information towards future modelling of the behaviour of Loy Yang coal in a full scale tangentially-fired furnace.
IOP Conference Series: Materials Science and Engineering
Computational Fluid Dynamics CFD modeling study was carried out to investigate the effect of the ... more Computational Fluid Dynamics CFD modeling study was carried out to investigate the effect of the pin fins arrangements over the flat plate heat sink. The pin fins were adopted with in-line array form over the surface of the heat sink with different parameters. The CFD domain was designed by the use of ANSYS FLUENT 2019 R1 commercial software. The Reynolds Average Naiver Stoke RANS turbulent model was used in this study to show accurately capture the effect of alternating acceleration and deceleration and consequent variations in the pressure field. The heat sink is in a rectangular shape with a rib length of 100mm and100mm. This CFD investigation included a simulation of the proposed heat sink under the forced convection with Reynolds number range of 2166.67 ∼ 19500 and subjected heat flux of 1000W/m2. Pin fins diameters range were 3, 6 and 9mm while the fin lengths range were 5, 10 and 15mm under the same the heat flux and Reynolds number. The predicted results showed an augmentati...
This paper presents a three-dimensional numerical investigation of pulverized dry lignite in a 10... more This paper presents a three-dimensional numerical investigation of pulverized dry lignite in a 100 kW oxyfuel furnace. A computational fluid dynamics (CFD) code was used to model four different combustion scenarios. One air-fired combustion case and three oxy-fuel-fired cases, known as OF25 (25 vol. % O2 concentration), OF27 (27 vol. % O2 concentration), and OF29 (29 vol. % O2 concentration), were modelled. User-defined functions (UDFs) for the multistep reaction schemes were written and incorporated to the CFD code. Under oxy-fuel combustion, the appropriate mathematical models were implemented to calculate the flame temperature distributions and species concentrations (O2 and CO2). The multi-step chemical reaction schemes were used for the gas-phase and solid-phase coal particle reactions. In addition to the one-step (reference) reaction scheme, twostep and three-step reaction schemes were considered in this numerical study. Compared to the one-step and twostep reactions, the thre...
The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted t... more The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted to simulate the conventional solar heating system, multipurpose solar water heater (MPSWH), and multipurpose solar air heater (MPSAH). The commercial computational fluid dynamics (CFD), AVL Fire ver. 2009.2 was used to solve and investigate the temperature distributions in the absorber plate and riser tube of both solar water and air heater during summer and winter seasons. The RNG k - turbulence model was employed for this CFD study.  The present paper was to provide a good understanding of thermal performance for the solar collector at different operating conditions. The experimental setup and physical data of  Venkatesh, R. and Christraj, W. [15] were employed as geometric parameters and initial boundary conditions to model and to validate the predicted numerical values. Comparing to the values of temperatures for the conventional SWH and SAH, the predicted results of the MPSWH and t...
A computational fluid dynamics (CFD) modelling study is undertaken integrating the air-fired and ... more A computational fluid dynamics (CFD) modelling study is undertaken integrating the air-fired and oxy-fuel combustion cases for chemical reactions, radiative heat transfer, and gas compositions into a 3-D hybrid unstructured grid CFD code. A swirl injection system is used to achieve the flame stability of the turbulent non-premixed combustible gases. An Eddy Breakup (EBU) combustion model with appropriate empirical coefficients is employed for this study. Validation and comparison of both combustion cases with the experimental data, which conducted on a 100 kW facility unit, were made by comparing the temperature distribution levels and species concentration levels. The oxy-fuel combustion case showed that the flame is obviously concentrated in the central region, and it is not spread inside the furnace compared to the air-fired flame. The swirl effect is certainly used to enhance the turbulent mixing and to achieve the internal recirculation of flames. By switching to oxy-fuel fired...
In the present paper, the effect of the Net Positive Suction Head (NPSH) for the centrifugal pump... more In the present paper, the effect of the Net Positive Suction Head (NPSH) for the centrifugal pump in a simple pipeline system has been carried out eliminating water hammer. Both the experimental tests and numerical calculations were performed in this study to investigate the transient flow effects when the discharges change abruptly in the system. The phenomenon of transient flow is generally occurred when the sudden opening of the downstream valves are used in the pumping station or due to introducing additional parallel branches of pipelines that contain pumps. Experimentally, two operational tests with different NPSH were conducted to show the relations between the head (H) and discharge (Q). The results of these tests showed two different types of H-Q curves. The first test produced a flat H-Q curve when the water surface level in the suction tank was 4 m above the center line of the pump. While in the second test the operational case created a steep H-Q curve when the pump was ...
This paper was recommended for publication in revised form by Regional Editor Nader Javani. 1 Dep... more This paper was recommended for publication in revised form by Regional Editor Nader Javani. 1 Department of Mechanical Engineering, Al-Nahrain University, Baghdad, IRAQ 2 Pumps Engineering Department, Technical College of Al-Musaib, Al-Furat Al-Awsat Technical University, Kufa, IRAQ 3 University Politehnica of Bucharest, Faculty of Power Engineering, Bucharest, Romania. *E-mail address: drahmed955@eng.nahrainuniv.edu.iq Orc d ID: 0000-0003-1965-1412, 0000-0002-5809-4105, 0000-0002-4352-4299, 0000-0002-5809-4105. Manuscript Received 28 March 2020, Accepted 16 June 2020 TURBULENT HEAT TRANSFER FOR INTERNAL FLOW OF ETHYLENE GLYCOLAL2O3 NANOFLUID IN A SPIRAL GROOVED TUBE WITH TWISTED TAPE INSERTS
In this study, experimental investigations and exergy analysis on shell and helically coiled tube... more In this study, experimental investigations and exergy analysis on shell and helically coiled tube heat exchanger are carried out for free convection heat transfer. The measured data are totally optimised utilizing thermodynamics rules in which exergy study is performed to investigate the thermal performance of the helical system under different operating conditions. The experimental set-up of apparatus are designed and made for cold water and hot water as a working fluid of both the shell side and helical coil side, respectively. The effects of several parameters such as geometry and operational conditions on the exergy destruction and dimensionless exergy destruction are investigated. The counter flow direction is considered under the steady state flow condition, and the critical Reynolds number was more than 4000 in this study. The main objective of this work was to clarify the effect of the volume flow rates and inlet temperatures of hot water and cold water in the shell and helical coil on exergy efficiency and pressure drop. Results showed that the exergy destruction and dimensionless exergy destruction decrease with the increase of coil pitch and Dean number. In contrast, the exergy destruction and dimensionless exergy destruction are obviously increased with the hot water flow rates or cold water flow rates. These exergy characteristics are also augmented with the values of hot water inlet temperatures and cold water inlet temperatures. The pressure drop is considerably increased with the increase of Dean number and reduced with the increase of coil diameter. While, the exergy efficiency steadily increases with the decrease of the cold water flow rates and with the increase of Dean number.
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Papers by Dr. Audai Hussein Al-Abbas