Sergio Nardini | Università della Campania Luigi Vanvitelli (original) (raw)

Papers by Sergio Nardini

Volume 4: Fatigue and Fracture, Heat Transfer, Internal Combustion Engines, Manufacturing, and Technology and Society, 2006

In this paper an experimental investigation on natural convection in air in inclined channels wit... more In this paper an experimental investigation on natural convection in air in inclined channels with rectangular transversal section and lower wall heated at uniform heat flux is carried out. Wall temperature measurements and flow visualization are presented. The results allow investigating on the effect of the distance between the two principal parallel walls and of the inclination angle. The experiments are accomplished for two channel gap values: 20 and 40 mm. The inclination angle is equal to 80° and 88°. The flow development and the shape of ...

The home of the Transactions of the Wessex Institute collection, providing on-line access to pape... more The home of the Transactions of the Wessex Institute collection, providing on-line access to papers presented at the Institute's prestigious international conferences and from its State-of-the-Art in Science & Engineering publications. ... Abstract: A study on sensible thermal energy storage (TES) for high temperature solar systems is numerically accomplished. ... The high temperature TES is cylindrical, the fluid and the solid thermo-physical properties are temperature independent and the radiation heat transfer mechanism is neglected. ... The commercial CFD Fluent ...

The home of the Transactions of the Wessex Institute collection, providing on-line access to pape... more The home of the Transactions of the Wessex Institute collection, providing on-line access to papers presented at the Institute's prestigious international conferences and from its State-of-the-Art in Science & Engineering publications. ... Abstract: Natural and mixed convection in air in an inclined channel with the lower wall heated at uniform heat flux and in the presence of an obstacle either at the entrance or exit of the channel is investigated experimentally and numerically, respectively. ... The study is accomplished for several heat fluxes. ... In mixed convection ...

Ice formation on airplane wing profile is a very dangerous condition because of the change in the... more Ice formation on airplane wing profile is a very dangerous condition because of the change in the profile aerodynamic, so it's necessary to avoid ice formation on the wings. The hardest condition ice formation are at altitudes between 10.000 and 15.000 ft and at temperature between 0° C and− 15° C, because they are particularly suitable for ice formation. In this paper an anti-icing system based on hot air impinging jets on internal wing surface is analyzed in order to check the efficiency of the system. A numerical model is given in ...

Abstract Mixed convection in open cavities filled with a porous medium with one heated wall at un... more Abstract Mixed convection in open cavities filled with a porous medium with one heated wall at uniform heat flux is studied numerically. The investigated configurations are: a horizontal channel with a cavity at the lower wall (U-shaped cavity); a vertical channel with a cavity at a wall (C-Shaped cavity). A two dimensional steady state investigation is carried out in order to evaluate the main natural and basic behaviours of the assisting flows that arise employing the Brinkman-Forchheimerextended Darcy model.

Abstract: A two dimensional instationary analysis of the conjugate optical-thermal fields induced... more Abstract: A two dimensional instationary analysis of the conjugate optical-thermal fields induced in a multilayer thin film structure by a moving Gaussian laser source is carried out numerically in order to compare back and front laser treatment processes. The work-piece is considered semi-infinite along the motion direction and different thicknesses of the thin film are considered. Thermal and optical nonlinearity is induced during transient heating, since the response of weakly absorbing thin films depends on temperature.

Abstract. In this work transient mixed convection in a porous medium in a horizontal channel with... more Abstract. In this work transient mixed convection in a porous medium in a horizontal channel with a open cavity below is studied numerically. The cavity presents a heated wall at uniform heat flux and the other walls of the cavity and the channel are assumed adiabatic. Air flows through the horizontal channel. The heated wall of the cavity experiences a uniform heat flux in such a way that the forced flow is perpendicular to the motion due to natural convection.

Abstract Mixed convection in air in a horizontal channel with the lower wall heated at uniform he... more Abstract Mixed convection in air in a horizontal channel with the lower wall heated at uniform heat flux is investigated experimentally. The study is accomplished for several heat fluxes, forced air velocities and two distances between the horizontal plates, b= 20 mm and b= 40 mm. The Reynolds numbers investigated are between 5.0 and 250, these being in the laminar regime. The Richardson number, Ri= Gr/Re 2, holds values in the range 3.0–7.4 x10 4.

Abstract: A numerical analysis on transient three-dimensional temperature distribution in a semi-... more Abstract: A numerical analysis on transient three-dimensional temperature distribution in a semi-infinite solid, irradiated by a moving Gaussian laser beam, is carried out numerically by means of the code COMSOL Multiphysics 3.3.. The investigated work-piece is simply a solid. A laser source is considered moving with constant velocity along the motion direction. The convective heat transfer on the upper surface of the solid is taken into account to simulate an impinging jet.

begellhouse.com

... JETS AND AN ONCMOING CROSSFLOW ON THEIR RESULTING HEAT TRANSFER Amina Radhouane, Nejla Mahjou... more ... JETS AND AN ONCMOING CROSSFLOW ON THEIR RESULTING HEAT TRANSFER Amina Radhouane, Nejla Mahjoub, Hatem Mhiri ... EXPERIMENTAL INVESTIGATION OF SOLAR DRYING FOR ORANGE PEELS BY FORCED CONVECTION Romdhane Ben Slama, Fethi ...

ICHMT DIGITAL LIBRARY …, 2009

ABSTRACT Conventional sources of energy have been depleting at an alarming rate, which makes futu... more ABSTRACT Conventional sources of energy have been depleting at an alarming rate, which makes future sustainable development of energy use very difficult. Thus, heat transfer enhancement technology plays an important part and it has been developed and widely applied to many applications as heat exchangers for refrigeration, automotives, process industry, solar heater etc. Several techniques for heat transfer enhancement are available. Enhancement of heat transfer performance especially in shell and tube heat exchangers ...

In this paper transient natural convection in a vertical convergent channel with or without satur... more In this paper transient natural convection in a vertical convergent channel with or without saturated porous medium is studied numerically. The investigation is carried out in laminar, two dimensional regime and employing the Brinkman-Forchheimer-extended Darcy model. The physical domain consists of two non-parallel plates which form a convergent channel. Both plates are heated at uniform heat flux. The solutions are achieved using the commercial code FLUENT. A finite-extension computational domain is employed to ...

Applied Thermal Engineering, 2011

In this paper a numerical investigation on forced convection with nanofluids, composed by water a... more In this paper a numerical investigation on forced convection with nanofluids, composed by water and Al2O3 nanoparticles, in a two-dimensional channel is carried out. A uniform heat flux is applied on the external walls. A single-phase approach is employed to model nanofluids and the fluid properties are considered constant with temperature. The particle size is set equal to 38nm and nanoparticle volume fractions from 0% to 4% are considered. The flow regime is turbulent and Reynolds numbers are in the range 20,000–60,000. ...

Nowadays trends in natural convection heat transfer are oriented toward either the seeking of new... more Nowadays trends in natural convection heat transfer are oriented toward either the seeking of new configurations to enhance the heat transfer parameters or the optimization of standard configurations. An experimental investigation on air natural convection in divergent channels with uniform heat flux at both the principal walls is presented in this paper to analyze the effect of radiative heat transfer. Results in terms of wall temperature profiles as a function of the walls diverging angle, the interwall spacing, the heat flux are given for two ...

The laminar field and heat transfer enhancement of forced convection in various counterflow porou... more The laminar field and heat transfer enhancement of forced convection in various counterflow porous channels with a joint aluminum plate was studied, using control volume technique and SIMPLE procedure for the velocity-pressure Coupling. Hydrodynamic and heat transfer results are reported for three configurations: (1) nonporous channels (NPC) (2) both channels filled by porous structure (BPC), and (3) only the channel contains hot fluid, filled by porous structure and other one is nonporous (HPC). The effectiveness, pressure drop and temperature difference are evaluated for wide ranges of Darcy, Reynolds and Prandtl numbers, also effects of thermal conductivity ratio is considered. The results show that as the Darcy, Reynolds or Prandtl number decreases, an increase in effectiveness is obtained. Also increase of thermal conductivity ratio causes to different effects on effectiveness in each case.

Mixed convection in air in a horizontal channel with the lower wall heated at uniform heat flux i... more Mixed convection in air in a horizontal channel with the lower wall heated at uniform heat flux is investigated experimentally. The study is accomplished for several heat fluxes, forced air velocities and two distances between the horizontal plates, b=20 mm and b=40 mm. The Reynolds numbers investigated are between 5.0 and 250, these being in the laminar regime. The Richardson number, Ri=Gr/Re 2 , holds values in the range 3.0 -7.4x10 4 . The effect of the channel gap is investigated by flow visualization and wall temperature distribution. Secondary motions are detected and it is founded that increasing the Rayleigh number secondary motions increase whereas increasing the Reynolds number secondary motions decrease. Moreover correlations for Nusselt number and dimensionless separation point are proposed as function of Grashof, Richardson and Rayleigh numbers and aspect ratios.

Volume 4: Fatigue and Fracture, Heat Transfer, Internal Combustion Engines, Manufacturing, and Technology and Society, 2006

In this paper an experimental investigation on natural convection in air in inclined channels wit... more In this paper an experimental investigation on natural convection in air in inclined channels with rectangular transversal section and lower wall heated at uniform heat flux is carried out. Wall temperature measurements and flow visualization are presented. The results allow investigating on the effect of the distance between the two principal parallel walls and of the inclination angle. The experiments are accomplished for two channel gap values: 20 and 40 mm. The inclination angle is equal to 80° and 88°. The flow development and the shape of ...

The home of the Transactions of the Wessex Institute collection, providing on-line access to pape... more The home of the Transactions of the Wessex Institute collection, providing on-line access to papers presented at the Institute's prestigious international conferences and from its State-of-the-Art in Science & Engineering publications. ... Abstract: A study on sensible thermal energy storage (TES) for high temperature solar systems is numerically accomplished. ... The high temperature TES is cylindrical, the fluid and the solid thermo-physical properties are temperature independent and the radiation heat transfer mechanism is neglected. ... The commercial CFD Fluent ...

The home of the Transactions of the Wessex Institute collection, providing on-line access to pape... more The home of the Transactions of the Wessex Institute collection, providing on-line access to papers presented at the Institute's prestigious international conferences and from its State-of-the-Art in Science & Engineering publications. ... Abstract: Natural and mixed convection in air in an inclined channel with the lower wall heated at uniform heat flux and in the presence of an obstacle either at the entrance or exit of the channel is investigated experimentally and numerically, respectively. ... The study is accomplished for several heat fluxes. ... In mixed convection ...

Ice formation on airplane wing profile is a very dangerous condition because of the change in the... more Ice formation on airplane wing profile is a very dangerous condition because of the change in the profile aerodynamic, so it's necessary to avoid ice formation on the wings. The hardest condition ice formation are at altitudes between 10.000 and 15.000 ft and at temperature between 0° C and− 15° C, because they are particularly suitable for ice formation. In this paper an anti-icing system based on hot air impinging jets on internal wing surface is analyzed in order to check the efficiency of the system. A numerical model is given in ...

Abstract Mixed convection in open cavities filled with a porous medium with one heated wall at un... more Abstract Mixed convection in open cavities filled with a porous medium with one heated wall at uniform heat flux is studied numerically. The investigated configurations are: a horizontal channel with a cavity at the lower wall (U-shaped cavity); a vertical channel with a cavity at a wall (C-Shaped cavity). A two dimensional steady state investigation is carried out in order to evaluate the main natural and basic behaviours of the assisting flows that arise employing the Brinkman-Forchheimerextended Darcy model.

Abstract: A two dimensional instationary analysis of the conjugate optical-thermal fields induced... more Abstract: A two dimensional instationary analysis of the conjugate optical-thermal fields induced in a multilayer thin film structure by a moving Gaussian laser source is carried out numerically in order to compare back and front laser treatment processes. The work-piece is considered semi-infinite along the motion direction and different thicknesses of the thin film are considered. Thermal and optical nonlinearity is induced during transient heating, since the response of weakly absorbing thin films depends on temperature.

Abstract. In this work transient mixed convection in a porous medium in a horizontal channel with... more Abstract. In this work transient mixed convection in a porous medium in a horizontal channel with a open cavity below is studied numerically. The cavity presents a heated wall at uniform heat flux and the other walls of the cavity and the channel are assumed adiabatic. Air flows through the horizontal channel. The heated wall of the cavity experiences a uniform heat flux in such a way that the forced flow is perpendicular to the motion due to natural convection.

Abstract Mixed convection in air in a horizontal channel with the lower wall heated at uniform he... more Abstract Mixed convection in air in a horizontal channel with the lower wall heated at uniform heat flux is investigated experimentally. The study is accomplished for several heat fluxes, forced air velocities and two distances between the horizontal plates, b= 20 mm and b= 40 mm. The Reynolds numbers investigated are between 5.0 and 250, these being in the laminar regime. The Richardson number, Ri= Gr/Re 2, holds values in the range 3.0–7.4 x10 4.

Abstract: A numerical analysis on transient three-dimensional temperature distribution in a semi-... more Abstract: A numerical analysis on transient three-dimensional temperature distribution in a semi-infinite solid, irradiated by a moving Gaussian laser beam, is carried out numerically by means of the code COMSOL Multiphysics 3.3.. The investigated work-piece is simply a solid. A laser source is considered moving with constant velocity along the motion direction. The convective heat transfer on the upper surface of the solid is taken into account to simulate an impinging jet.

begellhouse.com

... JETS AND AN ONCMOING CROSSFLOW ON THEIR RESULTING HEAT TRANSFER Amina Radhouane, Nejla Mahjou... more ... JETS AND AN ONCMOING CROSSFLOW ON THEIR RESULTING HEAT TRANSFER Amina Radhouane, Nejla Mahjoub, Hatem Mhiri ... EXPERIMENTAL INVESTIGATION OF SOLAR DRYING FOR ORANGE PEELS BY FORCED CONVECTION Romdhane Ben Slama, Fethi ...

ICHMT DIGITAL LIBRARY …, 2009

ABSTRACT Conventional sources of energy have been depleting at an alarming rate, which makes futu... more ABSTRACT Conventional sources of energy have been depleting at an alarming rate, which makes future sustainable development of energy use very difficult. Thus, heat transfer enhancement technology plays an important part and it has been developed and widely applied to many applications as heat exchangers for refrigeration, automotives, process industry, solar heater etc. Several techniques for heat transfer enhancement are available. Enhancement of heat transfer performance especially in shell and tube heat exchangers ...

In this paper transient natural convection in a vertical convergent channel with or without satur... more In this paper transient natural convection in a vertical convergent channel with or without saturated porous medium is studied numerically. The investigation is carried out in laminar, two dimensional regime and employing the Brinkman-Forchheimer-extended Darcy model. The physical domain consists of two non-parallel plates which form a convergent channel. Both plates are heated at uniform heat flux. The solutions are achieved using the commercial code FLUENT. A finite-extension computational domain is employed to ...

Applied Thermal Engineering, 2011

In this paper a numerical investigation on forced convection with nanofluids, composed by water a... more In this paper a numerical investigation on forced convection with nanofluids, composed by water and Al2O3 nanoparticles, in a two-dimensional channel is carried out. A uniform heat flux is applied on the external walls. A single-phase approach is employed to model nanofluids and the fluid properties are considered constant with temperature. The particle size is set equal to 38nm and nanoparticle volume fractions from 0% to 4% are considered. The flow regime is turbulent and Reynolds numbers are in the range 20,000–60,000. ...

Nowadays trends in natural convection heat transfer are oriented toward either the seeking of new... more Nowadays trends in natural convection heat transfer are oriented toward either the seeking of new configurations to enhance the heat transfer parameters or the optimization of standard configurations. An experimental investigation on air natural convection in divergent channels with uniform heat flux at both the principal walls is presented in this paper to analyze the effect of radiative heat transfer. Results in terms of wall temperature profiles as a function of the walls diverging angle, the interwall spacing, the heat flux are given for two ...

The laminar field and heat transfer enhancement of forced convection in various counterflow porou... more The laminar field and heat transfer enhancement of forced convection in various counterflow porous channels with a joint aluminum plate was studied, using control volume technique and SIMPLE procedure for the velocity-pressure Coupling. Hydrodynamic and heat transfer results are reported for three configurations: (1) nonporous channels (NPC) (2) both channels filled by porous structure (BPC), and (3) only the channel contains hot fluid, filled by porous structure and other one is nonporous (HPC). The effectiveness, pressure drop and temperature difference are evaluated for wide ranges of Darcy, Reynolds and Prandtl numbers, also effects of thermal conductivity ratio is considered. The results show that as the Darcy, Reynolds or Prandtl number decreases, an increase in effectiveness is obtained. Also increase of thermal conductivity ratio causes to different effects on effectiveness in each case.

Mixed convection in air in a horizontal channel with the lower wall heated at uniform heat flux i... more Mixed convection in air in a horizontal channel with the lower wall heated at uniform heat flux is investigated experimentally. The study is accomplished for several heat fluxes, forced air velocities and two distances between the horizontal plates, b=20 mm and b=40 mm. The Reynolds numbers investigated are between 5.0 and 250, these being in the laminar regime. The Richardson number, Ri=Gr/Re 2 , holds values in the range 3.0 -7.4x10 4 . The effect of the channel gap is investigated by flow visualization and wall temperature distribution. Secondary motions are detected and it is founded that increasing the Rayleigh number secondary motions increase whereas increasing the Reynolds number secondary motions decrease. Moreover correlations for Nusselt number and dimensionless separation point are proposed as function of Grashof, Richardson and Rayleigh numbers and aspect ratios.