Hrishikesh Kulkarni | Tata Consultancy Services (original) (raw)

Papers by Hrishikesh Kulkarni

Applied Thermal Engineering, 2017

In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulver... more In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulverized coal combustion in a vertical pilot-scale furnace. The furnace with swirl burner is located at the Institute of Heat and Mass Transfer at RWTH Aachen University, where O 2 /CO 2 combustion environment was adopted to study pulverized coal combustion experimentally [Toporov et al. Combustion and Flame, 2008]. A two-dimensional axisymmetric domain has been used in this work with a Lagrangian method to track coal particles. Performances of different Reynolds-Averaged-Navier-Stokes (RANS) turbulence models have been investigated. The radiative heat transfer using discrete ordinate (DO) model coupled with variants of weighted-sum-of-grey-gases (WSGGM) methods has been examined. The results obtained by these models have been compared with the experimental data. The DO radiation model with domain based WSGGM and SST k-omega turbulence model showed a very good match with the experimental data among other tested models. The accuracy of predicted results was comparable to LES results available in the literature. It is observed that to get preliminary results the current simplified model is good enough with accuracy comparable to LES modelling. By using this validated model, the influence of combustion environments such as air, oxy-steam (O 2 /H 2 O) and oxy-RFG (O 2 /CO 2) on temperature and NO concentration distribution has been investigated. NO x produced was least in the oxy-steam environment.

2D simulation has been carried out to analyze pulverized coal combustion in oxy-fuel environment.... more 2D simulation has been carried out to analyze pulverized coal combustion in oxy-fuel environment. Radiation and turbulence models have been evaluated. The proposed simplified model has been validated against experimental data. Validated model has been used to evaluate the effects of combustion environments. a b s t r a c t In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulverized coal combustion in a vertical pilot-scale furnace. The furnace with swirl burner is located at the Institute of Heat and Mass Transfer at RWTH Aachen University, where O 2 /CO 2 combustion environment was adopted to study pulverized coal combustion experimentally (Toporov et al., 2008). A two-dimensional axisymmetric domain has been used in this work with a Lagrangian method to track coal particles. Performances of different Reynolds-Averaged-Navier-Stokes (RANS) turbulence models have been investigated. The radiative heat transfer using discrete ordinate (DO) model coupled with variants of weighted-sum-of-grey-gases (WSGGM) methods has been examined. The results obtained by these models have been compared with the experimental data. The DO radiation model with domain based WSGGM and SST k-omega turbulence model showed a very good match with the experimental data among other tested models. The accuracy of predicted results was comparable to LES results available in the literature. It is observed that to get preliminary results the current simplified model is good enough with accuracy comparable to LES modelling. By using this validated model, the influence of combustion environments such as air, oxy-steam (O 2 /H 2 O) and oxy-RFG (O 2 /CO 2) on temperature and NO concentration distribution has been investigated. NO x produced was least in the oxy-steam environment.

Oxy-coal combustion technology is one of the methods available to reduce emissions of greenhouse ... more Oxy-coal combustion technology is one of the methods available to reduce emissions of greenhouse gases. In order to retrofit existing coal-air combustion boilers with oxy-combustion boilers, detailed analysis of oxycoal combustion is necessary. Numerical modelling of oxycoal combustion provides important insight into different phenomenon occurring during coal combustion. This can also provide different ways to reduce pollutants formed during coal combustion by modification of burner geometry. RANS analysis of oxy-coal combustion of pulverised coal inside swirl combustor is done in this study. The results obtained are discussed in terms of axial velocity and temperature contours along with two dimensional plots. The numerical model is validated with experimental data available. These results show the presence of recirculation zone in the flow field and its effect on temperature field. It is inferred from the results that accurate prediction of recirculation zone is important for prediction of temperature field.

In electronic components, it is essential to provide for adequate cooling to ensure that overheat... more In electronic components, it is essential to provide for adequate cooling to ensure that overheating does not affect the performance. It has been observed that for short fins, (L/H ≤ 5) due to formation of stagnant zone, central portion of fin is ineffective. To overcome this problem central portion from plate fin is removed. By doing so average heat transfer coefficient of notched array was improved almost by 30percentage compared to normal plate fin array. In this study we present computational assessment of notched plate fin heat sink (NPFHS) & notched plate fin pin fin heat sink (NPFPFHS). Based on NPFHS, a NPFPFHS is constructed which is composed of a NPFHS and some columnar pins planted between notched plate fins. Limited experimentation is carried out for validation of numerical model. Numerical analysis is carried out to compare thermal performance of these two types of heat sinks under the condition of equal temperature difference between mean sink temperature and ambient temperature. The effects of fin spacing, fin height, pin fin diameter and temperature difference between fin and surroundings on the free convection heat transfer from horizontal fin arrays were studied. The analysis have been carried out for the two types of heat sinks with three different spacing, three different height, four temperature differences and three pin diameters.

Applied Thermal Engineering, 2017

In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulver... more In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulverized coal combustion in a vertical pilot-scale furnace. The furnace with swirl burner is located at the Institute of Heat and Mass Transfer at RWTH Aachen University, where O 2 /CO 2 combustion environment was adopted to study pulverized coal combustion experimentally [Toporov et al. Combustion and Flame, 2008]. A two-dimensional axisymmetric domain has been used in this work with a Lagrangian method to track coal particles. Performances of different Reynolds-Averaged-Navier-Stokes (RANS) turbulence models have been investigated. The radiative heat transfer using discrete ordinate (DO) model coupled with variants of weighted-sum-of-grey-gases (WSGGM) methods has been examined. The results obtained by these models have been compared with the experimental data. The DO radiation model with domain based WSGGM and SST k-omega turbulence model showed a very good match with the experimental data among other tested models. The accuracy of predicted results was comparable to LES results available in the literature. It is observed that to get preliminary results the current simplified model is good enough with accuracy comparable to LES modelling. By using this validated model, the influence of combustion environments such as air, oxy-steam (O 2 /H 2 O) and oxy-RFG (O 2 /CO 2) on temperature and NO concentration distribution has been investigated. NO x produced was least in the oxy-steam environment.

2D simulation has been carried out to analyze pulverized coal combustion in oxy-fuel environment.... more 2D simulation has been carried out to analyze pulverized coal combustion in oxy-fuel environment. Radiation and turbulence models have been evaluated. The proposed simplified model has been validated against experimental data. Validated model has been used to evaluate the effects of combustion environments. a b s t r a c t In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulverized coal combustion in a vertical pilot-scale furnace. The furnace with swirl burner is located at the Institute of Heat and Mass Transfer at RWTH Aachen University, where O 2 /CO 2 combustion environment was adopted to study pulverized coal combustion experimentally (Toporov et al., 2008). A two-dimensional axisymmetric domain has been used in this work with a Lagrangian method to track coal particles. Performances of different Reynolds-Averaged-Navier-Stokes (RANS) turbulence models have been investigated. The radiative heat transfer using discrete ordinate (DO) model coupled with variants of weighted-sum-of-grey-gases (WSGGM) methods has been examined. The results obtained by these models have been compared with the experimental data. The DO radiation model with domain based WSGGM and SST k-omega turbulence model showed a very good match with the experimental data among other tested models. The accuracy of predicted results was comparable to LES results available in the literature. It is observed that to get preliminary results the current simplified model is good enough with accuracy comparable to LES modelling. By using this validated model, the influence of combustion environments such as air, oxy-steam (O 2 /H 2 O) and oxy-RFG (O 2 /CO 2) on temperature and NO concentration distribution has been investigated. NO x produced was least in the oxy-steam environment.

Oxy-coal combustion technology is one of the methods available to reduce emissions of greenhouse ... more Oxy-coal combustion technology is one of the methods available to reduce emissions of greenhouse gases. In order to retrofit existing coal-air combustion boilers with oxy-combustion boilers, detailed analysis of oxycoal combustion is necessary. Numerical modelling of oxycoal combustion provides important insight into different phenomenon occurring during coal combustion. This can also provide different ways to reduce pollutants formed during coal combustion by modification of burner geometry. RANS analysis of oxy-coal combustion of pulverised coal inside swirl combustor is done in this study. The results obtained are discussed in terms of axial velocity and temperature contours along with two dimensional plots. The numerical model is validated with experimental data available. These results show the presence of recirculation zone in the flow field and its effect on temperature field. It is inferred from the results that accurate prediction of recirculation zone is important for prediction of temperature field.

In electronic components, it is essential to provide for adequate cooling to ensure that overheat... more In electronic components, it is essential to provide for adequate cooling to ensure that overheating does not affect the performance. It has been observed that for short fins, (L/H ≤ 5) due to formation of stagnant zone, central portion of fin is ineffective. To overcome this problem central portion from plate fin is removed. By doing so average heat transfer coefficient of notched array was improved almost by 30percentage compared to normal plate fin array. In this study we present computational assessment of notched plate fin heat sink (NPFHS) & notched plate fin pin fin heat sink (NPFPFHS). Based on NPFHS, a NPFPFHS is constructed which is composed of a NPFHS and some columnar pins planted between notched plate fins. Limited experimentation is carried out for validation of numerical model. Numerical analysis is carried out to compare thermal performance of these two types of heat sinks under the condition of equal temperature difference between mean sink temperature and ambient temperature. The effects of fin spacing, fin height, pin fin diameter and temperature difference between fin and surroundings on the free convection heat transfer from horizontal fin arrays were studied. The analysis have been carried out for the two types of heat sinks with three different spacing, three different height, four temperature differences and three pin diameters.