enrico sciubba - Academia.edu (original) (raw)
Papers by enrico sciubba
ABSTRACT Huge greenhouse gas (GHG) emission from fossil fuel combustion and unsatisfied energy re... more ABSTRACT Huge greenhouse gas (GHG) emission from fossil fuel combustion and unsatisfied energy requirement have forced China to inquire into and change to environmental friendly alternatives that are renewable to sustain the increasing energy demand. Therefore, renewable energy in China has experienced a prosperous development in the last decade and will continue to be the focus and key issue of future energy development planning. However, some environmentalists have long argued that whether renewable energy sources such as wind are preferable to fossil fuels (oil, natural gas and coal), and which kind of renewable energy are more clean and sustainable. Quantitative evaluation to answer these questions thereby should be conducted. As extended exergy accounting (EEA) is a systematic exergo-economic method that adopts a single quantifier to account for materials, energy, labor and capital and to compute a presumed environmental impact based on remediation costs, it is a powerful tool for handling sustainability issues. Thus, aiming at evaluating the sustainability of renewable energy, we employ EEA to monitor the sustainability level of a wind power plant in China from the aspects of economic and environmental performance, and exergy efficiency. The results may provide some useful suggestions to support the environmentally sound renewable energy development.
A GTHV (gas turbine hybrid vehicle) is an electric vehicle (traction entirely electric on 1 or 2 ... more A GTHV (gas turbine hybrid vehicle) is an electric vehicle (traction entirely electric on 1 or 2 axles) equipped with a small turbogas whose only function is that of recharging the battery pack (and possibly other energy storage devices present on board). After a brief review of the history of the GTHV technology, a complete feasibility assessment of a prototype configuration of a GTHV designed by the University of Roma 1 is presented. All issues related to the system and component design, packaging, identification of the “optimal” hybridization ratio, performance of the (gas turbine + batteries + electrical motor) conversion system, braking energy recovery systems (KERS), mechanical and electric storage devices (flywheels, capacitors, advanced batteries), monitoring and control logic, compliance with the European vehicular ECE emission regulations, have been already discussed in several papers of the Authors. The paper analyzes the feasibility to insert “onboard” an innovative and ...
Energy and Buildings, 2013
The space conditioning sector is one of the highest energy consumers and of the least efficient f... more The space conditioning sector is one of the highest energy consumers and of the least efficient from the point of view of primary-to-end-use matching. In spite of the emergence, in the last decade, of innovative technical solutions based on renewable energy converters, installation of "new" devices without considering the whole picture (building + air conditioning system + energy conversion and supply chain) will hardly remedy the current situation. This study proposes a systemic approach to the joint design-and-analysis of space conditioning that leads to the identification of the thermodynamically most convenient configurations by integrating thermal building dissipation modeling, thermal consumption simulation and exergy efficiency calculation. The first step is the modeling of thermal characteristics of the building: the obtained temperature maps within the room are then used to compute, for each type of heating element, the actual thermal power required to ensure comfortable indoor temperature. The second step is the simulation of the "external" plant providing the prescribed thermal power, and is carried out by means of a process simulator: such a "global" simulation enables designers and decision makers to compare several feasible different combinations of internal and external systems and to identify the most exergetically convenient pairings.
International Journal of Heat and Mass Transfer, 1992
This paper reports the optimal board-to-board spacing and maximum total heat transfer rate from a... more This paper reports the optimal board-to-board spacing and maximum total heat transfer rate from a stack of parallel boards cooled by laminar forced convection. The optimal spacing is proportional to the board length raised to the power l/2, the property group (~cx)"~, and (AP)-',4, where AP is the pressure head maintained across the stack. The maximum total heat transfer rate is proportional to (AP) ' ', the total thickness of the stack (H), and the maximum allowable temperature difference between the board and the coolant inlet. Board surfaces with uniform temperature and uniform heat flux are considered. It is shown that the surface thermal condition (uniform temperature vs uniform heat flux) has a minor effect on the optimal spacing and the maximum total heat transfer rate.
Engineering Analysis with Boundary Elements, 2002
Problems solved by using different steady-state solution techniques in adjacent subregions are di... more Problems solved by using different steady-state solution techniques in adjacent subregions are discussed. The computational domain typically consists of two subregions, with a linear boundary value problem in one of them. BEM or analytical methods are used to solve the problem in this subregion. Static condensation of the off-interfacial degrees of freedom in this subdomain produces a linear set of equations linking nodal potentials and fluxes on the interface. This set of equations is generated by solving a sequence of boundary value problems in the linear subregion. Access to the source version of the software used to solve these boundary value problems is not required. Thus, the condensation can be accomplished using any commercial BEM code. The resulting set of equation is then treated as a boundary condition attached to the second subregion. In the latter, any numerical technique can be used and both linear and nonlinear problems may be considered. The paper addresses coupling of BEM and FEM, BEM and BEM and analytical solutions with BEM and FEM. Numerical examples are included.
Volume 6: Energy, Parts A and B, 2012
ABSTRACT A GTHV (gas turbine hybrid vehicle) is an electric vehicle with traction entirely electr... more ABSTRACT A GTHV (gas turbine hybrid vehicle) is an electric vehicle with traction entirely electric on 1 or 2 axles, equipped with a small turbogas whose only function is that of recharging the battery pack and possibly other energy storage devices present on board. After a brief review of the history of the GTHV technology, a complete feasibility assessment of a prototype configuration of a GTHV designed by the University of Roma 1 is presented. All issues related to the system and component design, packaging, identification of the "optimal" hybridization ratio, performance of the (gas turbine + batteries + electrical motor) conversion system, braking energy recovery systems (KERS), mechanical and electric storage devices (flywheels, capacitors, advanced batteries), monitoring and control logic, compliance with the European vehicular ECE emission regulations, have been already discussed in previous papers. The present study analyzes the feasibility to insert "on-board" an innovative and patented ORC (Organic Rankine Cycle) recovery system. In fact, the thermal source on the LETHE© vehicle is a turbogas of suitable power (10 to 30 kW depending on the vehicle class). The sensible heat of the exhaust gases is an ideal thermal source for an ORC system that can feed the car conditioning system and other auxiliaries. BRIEF REVIEW OF EXISTING HYBRID VEHICLES In the last decade, governmental incentives and the ever stricter emissions regulations have prompted some of the largest world automakers to dedicate resources to the study,
Volume 4: Fatigue and Fracture, Heat Transfer, Internal Combustion Engines, Manufacturing, and Technology and Society, 2006
A 2-d rectangular slab, internally cooled by circular tubes of different diameters, is used as a ... more A 2-d rectangular slab, internally cooled by circular tubes of different diameters, is used as a benchmark to perform a numerical thermal optimization procedure on a heat transfer configuration obtained by “constructal” considerations. Three different geometric arrangements are investigated: in the first one, all cooling holes have the same diameter; in the second, there are two hierarchies of holes with two different diameters; in the third, yet another series of smaller holes is added. To assist the user in systematically assembling multiple configurations, a custom user interface utility for generating constructal geometries has been developed. Thermal boundary conditions are assigned as if the slab were the axial cross-section of an elongated prismatic body, and as if the ducts were internally cooled by forced convection. For each case (single diameter of the cooling holes, 2 and 3 different diameters) a series of numerical simulations has been run to assess and compare the perf...
It is commonly (but erroneously) assumed that the best way to treat upstream boundaries for hyper... more It is commonly (but erroneously) assumed that the best way to treat upstream boundaries for hyperbolic equations is to let the numerical value be equal to the imposed value. What is erroneous in this assumption is that it ignores the presence of spurious numerical solutions which may have originated inside of the computational domain and which may be present near the boundary. Such spurious solutions are characterized by short wavelength spatial oscillations, with a group velocity, which is opposed to the direction of flow and are therefore moving as "packets" toward the boundary. They are reflected by the "standard" treatment whereas a better numerical treatment of the boundary should attempt to absorb them. This paper describes two methods for the modified numerical treatment of upstream boundaries of hyperbolic equations, which are effective in absorbing those purious solutions with a remainder which decreases as O (r-~J) and 0~~VA"-) respectively, where ...
This paper presents a general design approach involving automatic, intelligent process simulation... more This paper presents a general design approach involving automatic, intelligent process simulation procedures. The aim is to derive a general set of design principles and methodologies that can be developed into computer-assisted procedures. This first part deals with numerical, quantitative calculations, i.e., with what commonly goes under the name of “Numerical Process Simulation.” It is argued that the existing design methods can result in computer codes or packages that perform exactly (and deterministically) the numerical operations an engineer would perform. It is also shown that modularity in these codes is dictated by the necessity of automatically implementing numerical procedures that depend on the structure of the process under examination, rather than by user’s convenience and ease of maintenance. An example of a modular, structure-oriented code (CAMEL) is given and discussed in detail, while numerical applications are discussed elsewhere [4]. The second part deals with the more complex qualitative approach to process design, i.e., with the possibility of implementing automatic “expert” procedures that perform the same conceptual tasks as human process engineers. It is shown that by means of Artificial Intelligence techniques it is possible to mimic (to an extent) the “thinking patterns” of a human expert, and to produce process schemes that are both acceptable and realistic. A general process synthesis package (COLOMBO) is described and some of its applications discussed. The main goal of the two parts of the paper is to show that the very complex activity of process design can be executed automatically, not only in principle, but in actual applications, and that both qualitative synthesis and quantitative calculations are possible with the present state of the art of our computational facilities.
This paper describes the conceptual development and the prototype implementation of an Expert Sys... more This paper describes the conceptual development and the prototype implementation of an Expert System that deals with the prognosis and diagnosis of a significant subset of the operative faults of a cogeneration power plant. The expert system receives both raw and organised real-time information on the “instantaneous ” (actually, averaged over 60seconds intervals) plant operating conditions from a non-intelligent “plant interface” consisting of a standard plant data acquisition system and of a specific plant simulation software. This solution was adopted in view of possible future applications to industrial plants, where a low number of intrusive sensors is desirable: in this case, the simulator provides the missing data. The Inference Engine operates on the basis of a set of pre-defined rules that seek possible “faults chains ” expressed as combinations of a pre-assigned number of continuously calculated performance indicators, like the air filter output pressure drop, the relative ...
ABSTRACT Huge greenhouse gas (GHG) emission from fossil fuel combustion and unsatisfied energy re... more ABSTRACT Huge greenhouse gas (GHG) emission from fossil fuel combustion and unsatisfied energy requirement have forced China to inquire into and change to environmental friendly alternatives that are renewable to sustain the increasing energy demand. Therefore, renewable energy in China has experienced a prosperous development in the last decade and will continue to be the focus and key issue of future energy development planning. However, some environmentalists have long argued that whether renewable energy sources such as wind are preferable to fossil fuels (oil, natural gas and coal), and which kind of renewable energy are more clean and sustainable. Quantitative evaluation to answer these questions thereby should be conducted. As extended exergy accounting (EEA) is a systematic exergo-economic method that adopts a single quantifier to account for materials, energy, labor and capital and to compute a presumed environmental impact based on remediation costs, it is a powerful tool for handling sustainability issues. Thus, aiming at evaluating the sustainability of renewable energy, we employ EEA to monitor the sustainability level of a wind power plant in China from the aspects of economic and environmental performance, and exergy efficiency. The results may provide some useful suggestions to support the environmentally sound renewable energy development.
A GTHV (gas turbine hybrid vehicle) is an electric vehicle (traction entirely electric on 1 or 2 ... more A GTHV (gas turbine hybrid vehicle) is an electric vehicle (traction entirely electric on 1 or 2 axles) equipped with a small turbogas whose only function is that of recharging the battery pack (and possibly other energy storage devices present on board). After a brief review of the history of the GTHV technology, a complete feasibility assessment of a prototype configuration of a GTHV designed by the University of Roma 1 is presented. All issues related to the system and component design, packaging, identification of the “optimal” hybridization ratio, performance of the (gas turbine + batteries + electrical motor) conversion system, braking energy recovery systems (KERS), mechanical and electric storage devices (flywheels, capacitors, advanced batteries), monitoring and control logic, compliance with the European vehicular ECE emission regulations, have been already discussed in several papers of the Authors. The paper analyzes the feasibility to insert “onboard” an innovative and ...
Energy and Buildings, 2013
The space conditioning sector is one of the highest energy consumers and of the least efficient f... more The space conditioning sector is one of the highest energy consumers and of the least efficient from the point of view of primary-to-end-use matching. In spite of the emergence, in the last decade, of innovative technical solutions based on renewable energy converters, installation of "new" devices without considering the whole picture (building + air conditioning system + energy conversion and supply chain) will hardly remedy the current situation. This study proposes a systemic approach to the joint design-and-analysis of space conditioning that leads to the identification of the thermodynamically most convenient configurations by integrating thermal building dissipation modeling, thermal consumption simulation and exergy efficiency calculation. The first step is the modeling of thermal characteristics of the building: the obtained temperature maps within the room are then used to compute, for each type of heating element, the actual thermal power required to ensure comfortable indoor temperature. The second step is the simulation of the "external" plant providing the prescribed thermal power, and is carried out by means of a process simulator: such a "global" simulation enables designers and decision makers to compare several feasible different combinations of internal and external systems and to identify the most exergetically convenient pairings.
International Journal of Heat and Mass Transfer, 1992
This paper reports the optimal board-to-board spacing and maximum total heat transfer rate from a... more This paper reports the optimal board-to-board spacing and maximum total heat transfer rate from a stack of parallel boards cooled by laminar forced convection. The optimal spacing is proportional to the board length raised to the power l/2, the property group (~cx)"~, and (AP)-',4, where AP is the pressure head maintained across the stack. The maximum total heat transfer rate is proportional to (AP) ' ', the total thickness of the stack (H), and the maximum allowable temperature difference between the board and the coolant inlet. Board surfaces with uniform temperature and uniform heat flux are considered. It is shown that the surface thermal condition (uniform temperature vs uniform heat flux) has a minor effect on the optimal spacing and the maximum total heat transfer rate.
Engineering Analysis with Boundary Elements, 2002
Problems solved by using different steady-state solution techniques in adjacent subregions are di... more Problems solved by using different steady-state solution techniques in adjacent subregions are discussed. The computational domain typically consists of two subregions, with a linear boundary value problem in one of them. BEM or analytical methods are used to solve the problem in this subregion. Static condensation of the off-interfacial degrees of freedom in this subdomain produces a linear set of equations linking nodal potentials and fluxes on the interface. This set of equations is generated by solving a sequence of boundary value problems in the linear subregion. Access to the source version of the software used to solve these boundary value problems is not required. Thus, the condensation can be accomplished using any commercial BEM code. The resulting set of equation is then treated as a boundary condition attached to the second subregion. In the latter, any numerical technique can be used and both linear and nonlinear problems may be considered. The paper addresses coupling of BEM and FEM, BEM and BEM and analytical solutions with BEM and FEM. Numerical examples are included.
Volume 6: Energy, Parts A and B, 2012
ABSTRACT A GTHV (gas turbine hybrid vehicle) is an electric vehicle with traction entirely electr... more ABSTRACT A GTHV (gas turbine hybrid vehicle) is an electric vehicle with traction entirely electric on 1 or 2 axles, equipped with a small turbogas whose only function is that of recharging the battery pack and possibly other energy storage devices present on board. After a brief review of the history of the GTHV technology, a complete feasibility assessment of a prototype configuration of a GTHV designed by the University of Roma 1 is presented. All issues related to the system and component design, packaging, identification of the "optimal" hybridization ratio, performance of the (gas turbine + batteries + electrical motor) conversion system, braking energy recovery systems (KERS), mechanical and electric storage devices (flywheels, capacitors, advanced batteries), monitoring and control logic, compliance with the European vehicular ECE emission regulations, have been already discussed in previous papers. The present study analyzes the feasibility to insert "on-board" an innovative and patented ORC (Organic Rankine Cycle) recovery system. In fact, the thermal source on the LETHE© vehicle is a turbogas of suitable power (10 to 30 kW depending on the vehicle class). The sensible heat of the exhaust gases is an ideal thermal source for an ORC system that can feed the car conditioning system and other auxiliaries. BRIEF REVIEW OF EXISTING HYBRID VEHICLES In the last decade, governmental incentives and the ever stricter emissions regulations have prompted some of the largest world automakers to dedicate resources to the study,
Volume 4: Fatigue and Fracture, Heat Transfer, Internal Combustion Engines, Manufacturing, and Technology and Society, 2006
A 2-d rectangular slab, internally cooled by circular tubes of different diameters, is used as a ... more A 2-d rectangular slab, internally cooled by circular tubes of different diameters, is used as a benchmark to perform a numerical thermal optimization procedure on a heat transfer configuration obtained by “constructal” considerations. Three different geometric arrangements are investigated: in the first one, all cooling holes have the same diameter; in the second, there are two hierarchies of holes with two different diameters; in the third, yet another series of smaller holes is added. To assist the user in systematically assembling multiple configurations, a custom user interface utility for generating constructal geometries has been developed. Thermal boundary conditions are assigned as if the slab were the axial cross-section of an elongated prismatic body, and as if the ducts were internally cooled by forced convection. For each case (single diameter of the cooling holes, 2 and 3 different diameters) a series of numerical simulations has been run to assess and compare the perf...
It is commonly (but erroneously) assumed that the best way to treat upstream boundaries for hyper... more It is commonly (but erroneously) assumed that the best way to treat upstream boundaries for hyperbolic equations is to let the numerical value be equal to the imposed value. What is erroneous in this assumption is that it ignores the presence of spurious numerical solutions which may have originated inside of the computational domain and which may be present near the boundary. Such spurious solutions are characterized by short wavelength spatial oscillations, with a group velocity, which is opposed to the direction of flow and are therefore moving as "packets" toward the boundary. They are reflected by the "standard" treatment whereas a better numerical treatment of the boundary should attempt to absorb them. This paper describes two methods for the modified numerical treatment of upstream boundaries of hyperbolic equations, which are effective in absorbing those purious solutions with a remainder which decreases as O (r-~J) and 0~~VA"-) respectively, where ...
This paper presents a general design approach involving automatic, intelligent process simulation... more This paper presents a general design approach involving automatic, intelligent process simulation procedures. The aim is to derive a general set of design principles and methodologies that can be developed into computer-assisted procedures. This first part deals with numerical, quantitative calculations, i.e., with what commonly goes under the name of “Numerical Process Simulation.” It is argued that the existing design methods can result in computer codes or packages that perform exactly (and deterministically) the numerical operations an engineer would perform. It is also shown that modularity in these codes is dictated by the necessity of automatically implementing numerical procedures that depend on the structure of the process under examination, rather than by user’s convenience and ease of maintenance. An example of a modular, structure-oriented code (CAMEL) is given and discussed in detail, while numerical applications are discussed elsewhere [4]. The second part deals with the more complex qualitative approach to process design, i.e., with the possibility of implementing automatic “expert” procedures that perform the same conceptual tasks as human process engineers. It is shown that by means of Artificial Intelligence techniques it is possible to mimic (to an extent) the “thinking patterns” of a human expert, and to produce process schemes that are both acceptable and realistic. A general process synthesis package (COLOMBO) is described and some of its applications discussed. The main goal of the two parts of the paper is to show that the very complex activity of process design can be executed automatically, not only in principle, but in actual applications, and that both qualitative synthesis and quantitative calculations are possible with the present state of the art of our computational facilities.
This paper describes the conceptual development and the prototype implementation of an Expert Sys... more This paper describes the conceptual development and the prototype implementation of an Expert System that deals with the prognosis and diagnosis of a significant subset of the operative faults of a cogeneration power plant. The expert system receives both raw and organised real-time information on the “instantaneous ” (actually, averaged over 60seconds intervals) plant operating conditions from a non-intelligent “plant interface” consisting of a standard plant data acquisition system and of a specific plant simulation software. This solution was adopted in view of possible future applications to industrial plants, where a low number of intrusive sensors is desirable: in this case, the simulator provides the missing data. The Inference Engine operates on the basis of a set of pre-defined rules that seek possible “faults chains ” expressed as combinations of a pre-assigned number of continuously calculated performance indicators, like the air filter output pressure drop, the relative ...