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Papers by Silvio Vigna

Research paper thumbnail of Investigation on Thermal and Fluid Dynamic Behaviors in Mixed Convection in Horizontal Channels with Aluminum Foam and Heated from Below

E3S Web of Conferences, 2020

In this paper, mixed convection in a horizontal channel partially filled with a porous medium and... more In this paper, mixed convection in a horizontal channel partially filled with a porous medium and the lower wall heated at uniform heat flux is studied experimentally and numerically. A simplified two-dimensional problem is modelled and solved numerically. The domain is made of a principal channel and two channels with adiabatic walls, one upstream and the other one downstream the principal channel. The heated wall temperature profiles as a function of the Ri values are presented. Average Nusselt numbers are evaluated. The experimental test section is made up of a horizontal wall and a parallel adiabatic wall. The distance between the horizontal walls is equal to 40 mm. The porous medium is an aluminium foam and it is placed over the heated lower wall. The porous plate has a thickness equal to 20 mm. The aluminium foam has 10, 20 and 40 PPI. The experiments are performed with working fluid air. The Reynolds numbers investigated are between 5.0 and 250, these being in the laminar reg...

Research paper thumbnail of Transient Simulation of a Whey Drying Plant Assisted by Solar Energy

TECNICA ITALIANA-Italian Journal of Engineering Science, Jul 30, 2021

Research paper thumbnail of Analysis of the Parameters Required to Properly Define Nanofluids for Heat Transfer Applications

Fluids, Feb 2, 2021

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

Research paper thumbnail of Transient Simulation of a Solar Cooling System for an Agro-Industrial Application

Energy Procedia, 2018

Abstract The advantage of a solar cooling system is the simultaneity of strong sunlight and cooli... more Abstract The advantage of a solar cooling system is the simultaneity of strong sunlight and cooling demand in the summer season. In fact, when the demand of electricity reaches extreme peaks for the excessive use of air conditioners, solar energy is available. In this study, simulation based on a performance analysis of a solar cooling system is carried out by means of TRNSYS for an agro-industrial application. The configuration is fully modelled in TRNSYS and dynamic simulations are run for the entire year. First, the analysis determines the peak energy demand for a low-temperature room for an agro-industrial application located in the Naples area. The room is 11 m long, 9.50 m wide and 3.20 m high and a set-point temperature is assigned equal to 10°C. Two different types of collector (ETC and PTC) with a double effect (H 2 O-BrLi) chiller (150 kW) are considered. The analysis is carried out considering the optimal solar field area, collector slope and hot storage tank. A supplementary conventional boiler of 50 kW and a cold storage tank with volume 5 m 3 are also present. The terminal part of the system is constituted by fan coils. Various performance factors such as solar fraction, collector efficiency and primary energy savings are evaluated to optimize the key system design variables which include collector tilt, storage volume, type and size of the solar collector. Besides, a financial analysis is carried out.

Research paper thumbnail of Numerical Investigation on a Solar Chimney in a Building Façade under Different Climatic Condition

TECNICA ITALIANA-Italian Journal of Engineering Science

Solar chimney is a technology used to regulate the heat flow between indoor and outdoor of a buil... more Solar chimney is a technology used to regulate the heat flow between indoor and outdoor of a building. It employs solar radiation to increase the temperature of the air for optimize its circulation and by improving its quality. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 4.0 m high, 1.5 m wide whereas the thickness at the inlet the channel has a gap equal to 0.34 m and at the outlet it is 0.20 m. The chimney consists of a converging channel with one vertical wall and one inclined of 2°. The analysis is carried out on a threedimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. The simulations are carried out considering the solar irradiance for assigned geographical location and for a daily distribution in four different days, one for each climatic season. Further, comparison between the different results obtained by operating in quasisteady state regimes is examined and discussed. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles in order to evaluate the differences between the different configurations and thermal and fluid dynamic behaviors.

Research paper thumbnail of Investigation on Thermal and Fluid Dynamic Behaviors in Mixed Convection in Horizontal Channels with Aluminum Foam and Heated from Below

E3S Web of Conferences, 2020

In this paper, mixed convection in a horizontal channel partially filled with a porous medium and... more In this paper, mixed convection in a horizontal channel partially filled with a porous medium and the lower wall heated at uniform heat flux is studied experimentally and numerically. A simplified two-dimensional problem is modelled and solved numerically. The domain is made of a principal channel and two channels with adiabatic walls, one upstream and the other one downstream the principal channel. The heated wall temperature profiles as a function of the Ri values are presented. Average Nusselt numbers are evaluated. The experimental test section is made up of a horizontal wall and a parallel adiabatic wall. The distance between the horizontal walls is equal to 40 mm. The porous medium is an aluminium foam and it is placed over the heated lower wall. The porous plate has a thickness equal to 20 mm. The aluminium foam has 10, 20 and 40 PPI. The experiments are performed with working fluid air. The Reynolds numbers investigated are between 5.0 and 250, these being in the laminar reg...

Research paper thumbnail of Transient Simulation of a Whey Drying Plant Assisted by Solar Energy

TECNICA ITALIANA-Italian Journal of Engineering Science, Jul 30, 2021

Research paper thumbnail of Analysis of the Parameters Required to Properly Define Nanofluids for Heat Transfer Applications

Fluids, Feb 2, 2021

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

Research paper thumbnail of Transient Simulation of a Solar Cooling System for an Agro-Industrial Application

Energy Procedia, 2018

Abstract The advantage of a solar cooling system is the simultaneity of strong sunlight and cooli... more Abstract The advantage of a solar cooling system is the simultaneity of strong sunlight and cooling demand in the summer season. In fact, when the demand of electricity reaches extreme peaks for the excessive use of air conditioners, solar energy is available. In this study, simulation based on a performance analysis of a solar cooling system is carried out by means of TRNSYS for an agro-industrial application. The configuration is fully modelled in TRNSYS and dynamic simulations are run for the entire year. First, the analysis determines the peak energy demand for a low-temperature room for an agro-industrial application located in the Naples area. The room is 11 m long, 9.50 m wide and 3.20 m high and a set-point temperature is assigned equal to 10°C. Two different types of collector (ETC and PTC) with a double effect (H 2 O-BrLi) chiller (150 kW) are considered. The analysis is carried out considering the optimal solar field area, collector slope and hot storage tank. A supplementary conventional boiler of 50 kW and a cold storage tank with volume 5 m 3 are also present. The terminal part of the system is constituted by fan coils. Various performance factors such as solar fraction, collector efficiency and primary energy savings are evaluated to optimize the key system design variables which include collector tilt, storage volume, type and size of the solar collector. Besides, a financial analysis is carried out.

Research paper thumbnail of Numerical Investigation on a Solar Chimney in a Building Façade under Different Climatic Condition

TECNICA ITALIANA-Italian Journal of Engineering Science

Solar chimney is a technology used to regulate the heat flow between indoor and outdoor of a buil... more Solar chimney is a technology used to regulate the heat flow between indoor and outdoor of a building. It employs solar radiation to increase the temperature of the air for optimize its circulation and by improving its quality. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 4.0 m high, 1.5 m wide whereas the thickness at the inlet the channel has a gap equal to 0.34 m and at the outlet it is 0.20 m. The chimney consists of a converging channel with one vertical wall and one inclined of 2°. The analysis is carried out on a threedimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. The simulations are carried out considering the solar irradiance for assigned geographical location and for a daily distribution in four different days, one for each climatic season. Further, comparison between the different results obtained by operating in quasisteady state regimes is examined and discussed. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles in order to evaluate the differences between the different configurations and thermal and fluid dynamic behaviors.

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