Roberto Capata - Academia.edu (original) (raw)
Papers by Roberto Capata
This work aims to analyze the various types of peristaltic pumps by studying, in particular, the ... more This work aims to analyze the various types of peristaltic pumps by studying, in particular, the use of the peristaltic roller pump to highlight its critical issues and propose new effective and innovative solutions. One possible application of this device is in hemodialysis, which is a physical therapy substitution of kidney function that allows, in almost all cases, recovery and maintenance of the main biological functions while remaining the uremic condition. As for the extracorporeal one, the equipment used to purify the blood from toxic substances that are no longer normally eliminated by kidney filtration is divided mainly into two types: rotary peristaltic pump and a linear peristaltic pump. Having to work with a very particular fluid such as blood and in direct contact with the patient, they need to be extremely accurate and must ensure a constant and continuous functioning. The rotary peristaltic pump is the most widely used for hemodialysis and having been extensively studied in literature it has since found extensive solutions in the application field. As is well known, peristaltic pump refers to a device that exploits the principle of peristalsis to function, i.e. the transit of a bottleneck on a tube, in this case, the catheter, to push the fluid contained outwards. In particular, a roundabout peristaltic pump consists of a rotating structure consisting of two or more rollers that in turn revolve around their axis. With their displacement, the rollers clog adjacent catheter sections at a time so that after the first roller has passed the tube returns to its initial size creating the vacuum and then sucking the fluid. In this way, the liquid is pushed from the tube towards the patient. The motion of all these components is powered by an electric motor connected directly to the main rotating structure. The pumping of fluids through hoses using the propagation of a peristaltic wave has been the subject of design and scientific studies for more than 4 decades. This is easily justifiable since the phenomenon of peristalsis is known to be an important responsible mechanism of fluid transport in many biological organs. The goal is (starting on studies on the blood, a variable density fluid) to analyze in detail the peristaltic roller pump and propose its parametric optimization, aimed at determining the critical speed, beyond which the machine damages any kind of fluid that needs special treatment (blood, food, special gel, medical ointments and so on).
Energies, May 4, 2023
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
Journal of modern mechanical engineering and technology, Apr 7, 2023
A CAES (Compressed Air Energy System) plant can be considered as a storage system. The purpose is... more A CAES (Compressed Air Energy System) plant can be considered as a storage system. The purpose is to store air under pressure and then use it, when required, to generate energy. The system is composed of a series of compressors and heat exchangers and the architecture of the plant aims to reduce compression work and improve storage efficiency. The storage tank can be different depending on the case and the final use, so a cave, a combustion chamber or an expander. Currently the plants that have been built are in Germany (plant built in 1978 with a rated power of 290 MW) and in the USA (built in 1991 with a rated power of 110 MW). In both configurations, the plants use saline caves as reservoirs. Lately, different types of plant are being studied, but they are still in the design phase. The objective of the present work is, through a steady-state and then a dynamic simulation, to analyze the positive aspects of this technology and its criticalities, trying to optimize its layout. In addition, through a comparison with the few data available on existing plants, create a database of great interest for researchers and experts in the field. Finally, evaluate, based on the data obtained, the possible developments of technology in the context of the "low carbon transition" through the possible use of renewable sources, such as solar photovoltaic, wind and so on.
This work aims to analyze the various types of peristaltic pumps by studying, in particular, the ... more This work aims to analyze the various types of peristaltic pumps by studying, in particular, the use of the peristaltic roller pump to highlight its critical issues and propose new effective and innovative solutions. One possible application of this device is in hemodialysis, which is a physical therapy substitution of kidney function that allows, in almost all cases, recovery and maintenance of the main biological functions while remaining the uremic condition. As for the extracorporeal one, the equipment used to purify the blood from toxic substances that are no longer normally eliminated by kidney filtration is divided mainly into two types: rotary peristaltic pump and a linear peristaltic pump. Having to work with a very particular fluid such as blood and in direct contact with the patient, they need to be extremely accurate and must ensure a constant and continuous functioning. The rotary peristaltic pump is the most widely used for hemodialysis and having been extensively studied in literature it has since found extensive solutions in the application field. As is well known, peristaltic pump refers to a device that exploits the principle of peristalsis to function, i.e. the transit of a bottleneck on a tube, in this case, the catheter, to push the fluid contained outwards. In particular, a roundabout peristaltic pump consists of a rotating structure consisting of two or more rollers that in turn revolve around their axis. With their displacement, the rollers clog adjacent catheter sections at a time so that after the first roller has passed the tube returns to its initial size creating the vacuum and then sucking the fluid. In this way, the liquid is pushed from the tube towards the patient. The motion of all these components is powered by an electric motor connected directly to the main rotating structure. The pumping of fluids through hoses using the propagation of a peristaltic wave has been the subject of design and scientific studies for more than 4 decades. This is easily justifiable since the phenomenon of peristalsis is known to be an important responsible mechanism of fluid transport in many biological organs. The goal is (starting on studies on the blood, a variable density fluid) to analyze in detail the peristaltic roller pump and propose its parametric optimization, aimed at determining the critical speed, beyond which the machine damages any kind of fluid that needs special treatment (blood, food, special gel, medical ointments and so on).
This paper deals with the comparison between an IFR microturbine and a scroll-type expander for t... more This paper deals with the comparison between an IFR microturbine and a scroll-type expander for the exploitation of an on board ORC energy recovery system. The sensible heat recovered from a common bus engine (typically 8000cc) feeds the energy recovery system that can generate sufficient extra power to sustain the air-conditioning system and part of the auxiliaries. The concept is suitable for all kind of thermally propelled vehicles, but the application considered here is specific for an urban bus. The ORC cycle performance is calculated by a Process Simulator (CAMEL Pro) and the results are discussed. A preliminary design of the considered expanders is proposed using ad-hoc made models implemented in MATLAB, the technical constraints inherent to each machine are listed and the expected performance is presented in order to perform the optimal choice of the expander.
Energies, Jul 31, 2015
With the increasing popularity enjoyed by ultra-micro scale turbomachinery, designers are often f... more With the increasing popularity enjoyed by ultra-micro scale turbomachinery, designers are often faced with severe challenges due to the substantial phenomenological difference between the low-Reynolds fluid-dynamics in rotating or strongly curved flows and the established knowledge acquired through decades of theoretical and experimental studies on medium and large-scale machines. The problem is complicated by the absence of an extended and reliable database that might be used for preliminary design and provide indications for scale-up or scale-down. As a result, custom-designed experimental campaigns are necessary that make the development of any new machine exceedingly costly. The situation has seen some improvement in recent years, after the publication of a sufficient number of experimental results and numerical simulations that pave the way towards a development of semi-empirical correlations. The purpose of this work is to present and discuss a preliminary and simple method to extend the currently available design maps into the small scale range (Re < 10 5) by introducing in the Balje charts an efficiency correction that depends on the specific speed ns. The method results in a Stodola-like formula which originates a lower-than-standard Cordier curve on the classical Balje charts. A validation with some experimental results is also presented and discussed. Though the agreement is more than satisfactory, it must be stressed that the method provides only approximate results, and thus it must be considered as an evolving temporary solution, that needs to be updated as long as larger series of (numerical or physical) experimental results become available.
The research aims to verify the feasibility of an on-the-road prototype of a power train for a hy... more The research aims to verify the feasibility of an on-the-road prototype of a power train for a hybrid-powered vehicle. The current propulsion systems are built to increase the power of internal combustion engines as much as possible. The aim is to achieve this by keeping the size of the engine contained, but the complexity is such that to increase the power of a powertrain, maintaining its original dimensions and geometries unchanged, therefore its displacement, it is necessary to increase its maximum speed of rotation (rpm) or to increase the thermal and volumetric efficiency of the engine itself. It has been seen that the increase in power can be achieved through supercharging, i.e. through the introduction of a greater amount of air inside the cylinder, improving, through this device, the filling coefficient and therefore the volumetric efficiency. In addition, the research status is focused on ensuring lower fuel consumption, with cleaner and more efficient engines, in line with stringent anti-pollution regulations. This need has generated technical solutions such as downsizing and down speeding, for which it has been possible to reduce the number of cylinders, displacements, and rotational regimes in favor of efficiency. It should not be forgotten in this context the efforts made to ensure the reduction of the phenomenon of turbo-lag, together with the need to improve the operation of the engine in transients, especially at low speeds where greater torque is required. In detail, the study focuses on decoupling the overfeeding group. The preliminary proposal is to mechanically disconnect the compressor/turbine complex, supporting the rotation of compressor C with a dedicated electric motor and creating a turbine T connected to a generator. Mechanical decoupling C/T allows both machines to be designed so that they operate near the maximum efficiency point for most of the expected real operating range. Thus, the turbine will presumably have a slightly lower rotational speed than the original group and will therefore be slightly larger. Since the turbine is now disconnected from the compressor, the surplus is recovered at the high speeds that are usually discharged through the waste-gate valve, providing further turbine expansion. The subsequent generation of additional electrical power, can, after being cut from that required by the electric motor + compressor complex, be used where required (for example to power auxiliaries or recharge batteries in hybrid configuration). The study concludes, at the moment, with the evaluation of mechanical and thermal stresses (through a FEM analysis) to evaluate the coupling with the high-speed electric generator.
Energies, Mar 15, 2022
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
The research and development of low temperature differential Stirling engine has a great potentia... more The research and development of low temperature differential Stirling engine has a great potential market since a lot of thermal energy at low temperature can supply it and the cost of this kind of engine is lower than general Stirling engine. The characteristics of low compression ratio and low differential temperature Stirling engine may be satisfied with working fluid compressed on critical conditions. By combining two phase heat transfer with forced convective flow in compression space and through the regenerator in the engine, a new heat transfer coefficient emerges capable of absorbing and releasing high heat fluxes without the corresponding low temperature increase. The current analysis focuses on the study of Stirling engines with working fluid compressed on critical conditions, thus at two-phase heat transfer in compression space and regenerator of the engine under forced convective flow conditions.
Journal of energy and power engineering, Apr 28, 2015
The aim of this work is to analyze the performance of a commercial micro gas turbine, focusing on... more The aim of this work is to analyze the performance of a commercial micro gas turbine, focusing on the analysis of the fuel consumption and the outlet compressor and turbine temperature at various rpm, and to evaluate and compare the efficiency of the device. A test bench has been assembled with the available equipment in the laboratory of the department of mechanical and aerospace engineering in Roma. By using the software supplied by the manufacturer, the evaluation of the operating performance of the device at different speeds has been performed, obtaining all the values of interest.
36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2023)
The goal of this paper is to evaluate, from a thermodynamic point of view first, and then constru... more The goal of this paper is to evaluate, from a thermodynamic point of view first, and then constructive one, the possibility of inserting a waste heat recovery system in a hybrid vehicle in mild-hybrid configuration. The vehicle considered is a standard 1000 cc gasoline turbocharged ICE. The characteristic and proposed configuration of the vehicle allows to mechanically separate the existing turbo-compressor unit and to couple them with the respective electrical devices: electric motor and generator. This new architecture enables an electrical generation that can be used to recharge the installed battery package. Moreover, thanks to the new configuration of the turbine of the group, i.e. without the wastegate valve, the turbomachinery provides a high gas flow rate at high temperature (about 380 °C). These exhaust gases can be used for a bottom ORC group, with additional electricity generation. All these considerations permit to have an extra on-board recharge of the batteries, to consequently increase the electric range of the vehicle (a sort of range extender) and to install a battery group of limited size and power, with consequent advantages of payload and vehicle efficiency. Besides, it allows to achieve the well know and inflated aspects (from a citation point of view) of the emissions reduction.
34th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2021), 2022
Energies, 2021
As part of a project for the realization of a hybrid vehicle with an innovative power train syste... more As part of a project for the realization of a hybrid vehicle with an innovative power train system, the proposal presented is to disconnect the turbocharger group and study the different behavior of the compressor and turbine, so decoupled. In an actual turbocharger, when the power of the turbine exceeds that required by the compressor, the wastegate valve opens. In this way, a part of the flue gases does not evolve into a turbine and limits the power generated. In the solution proposed here (the paper considers only “compressor side”) all the flow rate of the flue gases is processed by the turbine. In this way, for each rpms of the IC engine, the turbine generates more power than that required by the compressor. This makes it possible to use this surplus of power for the auxiliaries and/or to recharge the battery pack of the considered hybrid vehicle. An additional advantage is, thanks to this surplus generated, that the battery pack can be smaller and can be recharged while drivin...
International Journal of Heat and Mass Transfer, 2019
The aim of this work is to continue the experimental evaluation of three different compact branch... more The aim of this work is to continue the experimental evaluation of three different compact branched heat exchangers. To complete the previous study, additional experimental tests were carried out, using a commercial automotive refrigerant (Glycol) at different concentrations (50%, 100%). Finally, in order to have a deeper knowledge of this phenomenon and to identify the parameters regulating the heat transfer, an organic fluid has also been used and tested. The use of such a fluid has required a re-elaboration and design of the test bench. In fact, a vacuum circuit has been realized to properly use the organic fluid. As a result, the equipment used has been changed and inserting more sophisticated sensors. Finally, once all the tests have been completed, the various dimensionless parameters, characterizing the heat exchange, have been calculated and a comparative evaluation has been carried out, to determine and propose the optimal configuration of the branched heat exchanger.
International Journal of Heat and Mass Transfer, 2017
The aim of this work is to experimentally evaluate three different compact branched heat exchange... more The aim of this work is to experimentally evaluate three different compact branched heat exchangers, measuring, for every single device, the thermal efficiency and the pressure drop. The generality of the analysis of phenomena is enhanced by a comparison of the performance of different refrigerant fluids. In the first configuration, the channels have been designed, varying the inner diameter, to allow for an average constant flow speed throughout the exchanger. In the second one, the flow Reynolds number inside of the channels has been maintained constant. The last configuration is built according to the constructal diameter variation, as indicated in Bejan Constructal Theory. The exchanger manufacturing process is described in detail. The test bench has been assembled using a hot source (Heating Plate with a power of 500 W) and a submersible pump, needed for the fluid recirculation, coupled with flowmeters, to control the mass flow rate within a specific range. The data obtained from several comparative tests have been analyzed, to determine the optimal solution for each refrigerant among the different exchangers.
Micromachines, 2015
Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are... more Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are still many different ways to accomplish it, most of which are still not sufficiently general, inexpensive, accurate, efficient or effective. Several problems arise both for in vivo or in vitro analysis, such as the maximum overall size of the device and the gripper jaws (like in minimally-invasive open biopsy) or very limited manipulating capability, degrees of freedom or dexterity (like in tissues or cell-handling operations). This paper presents a new approach to tissue and cell manipulation, which employs a conceptually new conjugate surfaces flexure hinge (CSFH) silicon MEMS-based technology micro-gripper that solves most of the above-mentioned problems. The article describes all of the phases of the development, including topology conception, structural design, simulation, construction, actuation testing and in vitro observation. The latter phase deals with the assessment of the function capability, which consists of taking a series of in vitro images by optical microscopy. They offer a direct morphological comparison between the gripper and a variety of tissues.
2015 IEEE 15th International Conference on Environment and Electrical Engineering (EEEIC), 2015
ABSTRACT New energy scenarios see renewable energy is no longer as marginal sources, but as actre... more ABSTRACT New energy scenarios see renewable energy is no longer as marginal sources, but as actresses able to change the energy market. The past few years have seen the energy market more fluid than that of past decades, the constant growth of the renewable component of the global energy mix has changed the relationship between offer-demand and also because of the changing geopolitical conditions, there has been a constant reduced costs of fossil fuels. This article intends to put highlight, in Italian, as the market fossil fuels is influenced by the penetration of renewable energy. In addition, by relating the benefits (economic and externalities), obtained from the dissemination of renewable, with the costs for promoting the development of renewable energies.
36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2023)
2021 AEIT International Conference on Electrical and Electronic Technologies for Automotive (AEIT AUTOMOTIVE), 2021
The paper reports the preliminary results of a study to develop and prototype a novel compact hyb... more The paper reports the preliminary results of a study to develop and prototype a novel compact hybrid powertrain for a small/medium urban vehicle. The aim is to improve a standard turbocharged gasoline engine's performance by utilizing various energy recovery systems. Most notable is a novel turbocharger with mechanically decoupled compressor and turbine. During operation, the turbine and compressor, which are connected to two different electric machines, contribute a net energy input to the battery pack. The mechanical decoupling also enables both machines to operate close to their maximum efficiency over the expected real operating range. A properly designed engine control unit (ECU) monitors and controls the angular velocities of the two machines separately, eliminating the need for a wastegate valve enabling a net surplus of electrical energy generated by the turbine. The study focuses on the compressor and its electric motor, which are two essential components of the suggested design. The two components must be developed together and their performance curves closely matched due to the extremely high speed required by the design criteria that dictate high power density. The compressor used is a modified Garrett GT12, and the electric motor is a high-speed prototype brushless unit. The design parameters and their impact on the operating ranges of both the compressor and the electric motor are described. After a description of the conceptual and technological issues encountered during the design, the proposed solutions are discussed in detail, with preliminary results reported.
This work aims to analyze the various types of peristaltic pumps by studying, in particular, the ... more This work aims to analyze the various types of peristaltic pumps by studying, in particular, the use of the peristaltic roller pump to highlight its critical issues and propose new effective and innovative solutions. One possible application of this device is in hemodialysis, which is a physical therapy substitution of kidney function that allows, in almost all cases, recovery and maintenance of the main biological functions while remaining the uremic condition. As for the extracorporeal one, the equipment used to purify the blood from toxic substances that are no longer normally eliminated by kidney filtration is divided mainly into two types: rotary peristaltic pump and a linear peristaltic pump. Having to work with a very particular fluid such as blood and in direct contact with the patient, they need to be extremely accurate and must ensure a constant and continuous functioning. The rotary peristaltic pump is the most widely used for hemodialysis and having been extensively studied in literature it has since found extensive solutions in the application field. As is well known, peristaltic pump refers to a device that exploits the principle of peristalsis to function, i.e. the transit of a bottleneck on a tube, in this case, the catheter, to push the fluid contained outwards. In particular, a roundabout peristaltic pump consists of a rotating structure consisting of two or more rollers that in turn revolve around their axis. With their displacement, the rollers clog adjacent catheter sections at a time so that after the first roller has passed the tube returns to its initial size creating the vacuum and then sucking the fluid. In this way, the liquid is pushed from the tube towards the patient. The motion of all these components is powered by an electric motor connected directly to the main rotating structure. The pumping of fluids through hoses using the propagation of a peristaltic wave has been the subject of design and scientific studies for more than 4 decades. This is easily justifiable since the phenomenon of peristalsis is known to be an important responsible mechanism of fluid transport in many biological organs. The goal is (starting on studies on the blood, a variable density fluid) to analyze in detail the peristaltic roller pump and propose its parametric optimization, aimed at determining the critical speed, beyond which the machine damages any kind of fluid that needs special treatment (blood, food, special gel, medical ointments and so on).
Energies, May 4, 2023
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
Journal of modern mechanical engineering and technology, Apr 7, 2023
A CAES (Compressed Air Energy System) plant can be considered as a storage system. The purpose is... more A CAES (Compressed Air Energy System) plant can be considered as a storage system. The purpose is to store air under pressure and then use it, when required, to generate energy. The system is composed of a series of compressors and heat exchangers and the architecture of the plant aims to reduce compression work and improve storage efficiency. The storage tank can be different depending on the case and the final use, so a cave, a combustion chamber or an expander. Currently the plants that have been built are in Germany (plant built in 1978 with a rated power of 290 MW) and in the USA (built in 1991 with a rated power of 110 MW). In both configurations, the plants use saline caves as reservoirs. Lately, different types of plant are being studied, but they are still in the design phase. The objective of the present work is, through a steady-state and then a dynamic simulation, to analyze the positive aspects of this technology and its criticalities, trying to optimize its layout. In addition, through a comparison with the few data available on existing plants, create a database of great interest for researchers and experts in the field. Finally, evaluate, based on the data obtained, the possible developments of technology in the context of the "low carbon transition" through the possible use of renewable sources, such as solar photovoltaic, wind and so on.
This work aims to analyze the various types of peristaltic pumps by studying, in particular, the ... more This work aims to analyze the various types of peristaltic pumps by studying, in particular, the use of the peristaltic roller pump to highlight its critical issues and propose new effective and innovative solutions. One possible application of this device is in hemodialysis, which is a physical therapy substitution of kidney function that allows, in almost all cases, recovery and maintenance of the main biological functions while remaining the uremic condition. As for the extracorporeal one, the equipment used to purify the blood from toxic substances that are no longer normally eliminated by kidney filtration is divided mainly into two types: rotary peristaltic pump and a linear peristaltic pump. Having to work with a very particular fluid such as blood and in direct contact with the patient, they need to be extremely accurate and must ensure a constant and continuous functioning. The rotary peristaltic pump is the most widely used for hemodialysis and having been extensively studied in literature it has since found extensive solutions in the application field. As is well known, peristaltic pump refers to a device that exploits the principle of peristalsis to function, i.e. the transit of a bottleneck on a tube, in this case, the catheter, to push the fluid contained outwards. In particular, a roundabout peristaltic pump consists of a rotating structure consisting of two or more rollers that in turn revolve around their axis. With their displacement, the rollers clog adjacent catheter sections at a time so that after the first roller has passed the tube returns to its initial size creating the vacuum and then sucking the fluid. In this way, the liquid is pushed from the tube towards the patient. The motion of all these components is powered by an electric motor connected directly to the main rotating structure. The pumping of fluids through hoses using the propagation of a peristaltic wave has been the subject of design and scientific studies for more than 4 decades. This is easily justifiable since the phenomenon of peristalsis is known to be an important responsible mechanism of fluid transport in many biological organs. The goal is (starting on studies on the blood, a variable density fluid) to analyze in detail the peristaltic roller pump and propose its parametric optimization, aimed at determining the critical speed, beyond which the machine damages any kind of fluid that needs special treatment (blood, food, special gel, medical ointments and so on).
This paper deals with the comparison between an IFR microturbine and a scroll-type expander for t... more This paper deals with the comparison between an IFR microturbine and a scroll-type expander for the exploitation of an on board ORC energy recovery system. The sensible heat recovered from a common bus engine (typically 8000cc) feeds the energy recovery system that can generate sufficient extra power to sustain the air-conditioning system and part of the auxiliaries. The concept is suitable for all kind of thermally propelled vehicles, but the application considered here is specific for an urban bus. The ORC cycle performance is calculated by a Process Simulator (CAMEL Pro) and the results are discussed. A preliminary design of the considered expanders is proposed using ad-hoc made models implemented in MATLAB, the technical constraints inherent to each machine are listed and the expected performance is presented in order to perform the optimal choice of the expander.
Energies, Jul 31, 2015
With the increasing popularity enjoyed by ultra-micro scale turbomachinery, designers are often f... more With the increasing popularity enjoyed by ultra-micro scale turbomachinery, designers are often faced with severe challenges due to the substantial phenomenological difference between the low-Reynolds fluid-dynamics in rotating or strongly curved flows and the established knowledge acquired through decades of theoretical and experimental studies on medium and large-scale machines. The problem is complicated by the absence of an extended and reliable database that might be used for preliminary design and provide indications for scale-up or scale-down. As a result, custom-designed experimental campaigns are necessary that make the development of any new machine exceedingly costly. The situation has seen some improvement in recent years, after the publication of a sufficient number of experimental results and numerical simulations that pave the way towards a development of semi-empirical correlations. The purpose of this work is to present and discuss a preliminary and simple method to extend the currently available design maps into the small scale range (Re < 10 5) by introducing in the Balje charts an efficiency correction that depends on the specific speed ns. The method results in a Stodola-like formula which originates a lower-than-standard Cordier curve on the classical Balje charts. A validation with some experimental results is also presented and discussed. Though the agreement is more than satisfactory, it must be stressed that the method provides only approximate results, and thus it must be considered as an evolving temporary solution, that needs to be updated as long as larger series of (numerical or physical) experimental results become available.
The research aims to verify the feasibility of an on-the-road prototype of a power train for a hy... more The research aims to verify the feasibility of an on-the-road prototype of a power train for a hybrid-powered vehicle. The current propulsion systems are built to increase the power of internal combustion engines as much as possible. The aim is to achieve this by keeping the size of the engine contained, but the complexity is such that to increase the power of a powertrain, maintaining its original dimensions and geometries unchanged, therefore its displacement, it is necessary to increase its maximum speed of rotation (rpm) or to increase the thermal and volumetric efficiency of the engine itself. It has been seen that the increase in power can be achieved through supercharging, i.e. through the introduction of a greater amount of air inside the cylinder, improving, through this device, the filling coefficient and therefore the volumetric efficiency. In addition, the research status is focused on ensuring lower fuel consumption, with cleaner and more efficient engines, in line with stringent anti-pollution regulations. This need has generated technical solutions such as downsizing and down speeding, for which it has been possible to reduce the number of cylinders, displacements, and rotational regimes in favor of efficiency. It should not be forgotten in this context the efforts made to ensure the reduction of the phenomenon of turbo-lag, together with the need to improve the operation of the engine in transients, especially at low speeds where greater torque is required. In detail, the study focuses on decoupling the overfeeding group. The preliminary proposal is to mechanically disconnect the compressor/turbine complex, supporting the rotation of compressor C with a dedicated electric motor and creating a turbine T connected to a generator. Mechanical decoupling C/T allows both machines to be designed so that they operate near the maximum efficiency point for most of the expected real operating range. Thus, the turbine will presumably have a slightly lower rotational speed than the original group and will therefore be slightly larger. Since the turbine is now disconnected from the compressor, the surplus is recovered at the high speeds that are usually discharged through the waste-gate valve, providing further turbine expansion. The subsequent generation of additional electrical power, can, after being cut from that required by the electric motor + compressor complex, be used where required (for example to power auxiliaries or recharge batteries in hybrid configuration). The study concludes, at the moment, with the evaluation of mechanical and thermal stresses (through a FEM analysis) to evaluate the coupling with the high-speed electric generator.
Energies, Mar 15, 2022
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
The research and development of low temperature differential Stirling engine has a great potentia... more The research and development of low temperature differential Stirling engine has a great potential market since a lot of thermal energy at low temperature can supply it and the cost of this kind of engine is lower than general Stirling engine. The characteristics of low compression ratio and low differential temperature Stirling engine may be satisfied with working fluid compressed on critical conditions. By combining two phase heat transfer with forced convective flow in compression space and through the regenerator in the engine, a new heat transfer coefficient emerges capable of absorbing and releasing high heat fluxes without the corresponding low temperature increase. The current analysis focuses on the study of Stirling engines with working fluid compressed on critical conditions, thus at two-phase heat transfer in compression space and regenerator of the engine under forced convective flow conditions.
Journal of energy and power engineering, Apr 28, 2015
The aim of this work is to analyze the performance of a commercial micro gas turbine, focusing on... more The aim of this work is to analyze the performance of a commercial micro gas turbine, focusing on the analysis of the fuel consumption and the outlet compressor and turbine temperature at various rpm, and to evaluate and compare the efficiency of the device. A test bench has been assembled with the available equipment in the laboratory of the department of mechanical and aerospace engineering in Roma. By using the software supplied by the manufacturer, the evaluation of the operating performance of the device at different speeds has been performed, obtaining all the values of interest.
36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2023)
The goal of this paper is to evaluate, from a thermodynamic point of view first, and then constru... more The goal of this paper is to evaluate, from a thermodynamic point of view first, and then constructive one, the possibility of inserting a waste heat recovery system in a hybrid vehicle in mild-hybrid configuration. The vehicle considered is a standard 1000 cc gasoline turbocharged ICE. The characteristic and proposed configuration of the vehicle allows to mechanically separate the existing turbo-compressor unit and to couple them with the respective electrical devices: electric motor and generator. This new architecture enables an electrical generation that can be used to recharge the installed battery package. Moreover, thanks to the new configuration of the turbine of the group, i.e. without the wastegate valve, the turbomachinery provides a high gas flow rate at high temperature (about 380 °C). These exhaust gases can be used for a bottom ORC group, with additional electricity generation. All these considerations permit to have an extra on-board recharge of the batteries, to consequently increase the electric range of the vehicle (a sort of range extender) and to install a battery group of limited size and power, with consequent advantages of payload and vehicle efficiency. Besides, it allows to achieve the well know and inflated aspects (from a citation point of view) of the emissions reduction.
34th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2021), 2022
Energies, 2021
As part of a project for the realization of a hybrid vehicle with an innovative power train syste... more As part of a project for the realization of a hybrid vehicle with an innovative power train system, the proposal presented is to disconnect the turbocharger group and study the different behavior of the compressor and turbine, so decoupled. In an actual turbocharger, when the power of the turbine exceeds that required by the compressor, the wastegate valve opens. In this way, a part of the flue gases does not evolve into a turbine and limits the power generated. In the solution proposed here (the paper considers only “compressor side”) all the flow rate of the flue gases is processed by the turbine. In this way, for each rpms of the IC engine, the turbine generates more power than that required by the compressor. This makes it possible to use this surplus of power for the auxiliaries and/or to recharge the battery pack of the considered hybrid vehicle. An additional advantage is, thanks to this surplus generated, that the battery pack can be smaller and can be recharged while drivin...
International Journal of Heat and Mass Transfer, 2019
The aim of this work is to continue the experimental evaluation of three different compact branch... more The aim of this work is to continue the experimental evaluation of three different compact branched heat exchangers. To complete the previous study, additional experimental tests were carried out, using a commercial automotive refrigerant (Glycol) at different concentrations (50%, 100%). Finally, in order to have a deeper knowledge of this phenomenon and to identify the parameters regulating the heat transfer, an organic fluid has also been used and tested. The use of such a fluid has required a re-elaboration and design of the test bench. In fact, a vacuum circuit has been realized to properly use the organic fluid. As a result, the equipment used has been changed and inserting more sophisticated sensors. Finally, once all the tests have been completed, the various dimensionless parameters, characterizing the heat exchange, have been calculated and a comparative evaluation has been carried out, to determine and propose the optimal configuration of the branched heat exchanger.
International Journal of Heat and Mass Transfer, 2017
The aim of this work is to experimentally evaluate three different compact branched heat exchange... more The aim of this work is to experimentally evaluate three different compact branched heat exchangers, measuring, for every single device, the thermal efficiency and the pressure drop. The generality of the analysis of phenomena is enhanced by a comparison of the performance of different refrigerant fluids. In the first configuration, the channels have been designed, varying the inner diameter, to allow for an average constant flow speed throughout the exchanger. In the second one, the flow Reynolds number inside of the channels has been maintained constant. The last configuration is built according to the constructal diameter variation, as indicated in Bejan Constructal Theory. The exchanger manufacturing process is described in detail. The test bench has been assembled using a hot source (Heating Plate with a power of 500 W) and a submersible pump, needed for the fluid recirculation, coupled with flowmeters, to control the mass flow rate within a specific range. The data obtained from several comparative tests have been analyzed, to determine the optimal solution for each refrigerant among the different exchangers.
Micromachines, 2015
Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are... more Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are still many different ways to accomplish it, most of which are still not sufficiently general, inexpensive, accurate, efficient or effective. Several problems arise both for in vivo or in vitro analysis, such as the maximum overall size of the device and the gripper jaws (like in minimally-invasive open biopsy) or very limited manipulating capability, degrees of freedom or dexterity (like in tissues or cell-handling operations). This paper presents a new approach to tissue and cell manipulation, which employs a conceptually new conjugate surfaces flexure hinge (CSFH) silicon MEMS-based technology micro-gripper that solves most of the above-mentioned problems. The article describes all of the phases of the development, including topology conception, structural design, simulation, construction, actuation testing and in vitro observation. The latter phase deals with the assessment of the function capability, which consists of taking a series of in vitro images by optical microscopy. They offer a direct morphological comparison between the gripper and a variety of tissues.
2015 IEEE 15th International Conference on Environment and Electrical Engineering (EEEIC), 2015
ABSTRACT New energy scenarios see renewable energy is no longer as marginal sources, but as actre... more ABSTRACT New energy scenarios see renewable energy is no longer as marginal sources, but as actresses able to change the energy market. The past few years have seen the energy market more fluid than that of past decades, the constant growth of the renewable component of the global energy mix has changed the relationship between offer-demand and also because of the changing geopolitical conditions, there has been a constant reduced costs of fossil fuels. This article intends to put highlight, in Italian, as the market fossil fuels is influenced by the penetration of renewable energy. In addition, by relating the benefits (economic and externalities), obtained from the dissemination of renewable, with the costs for promoting the development of renewable energies.
36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2023)
2021 AEIT International Conference on Electrical and Electronic Technologies for Automotive (AEIT AUTOMOTIVE), 2021
The paper reports the preliminary results of a study to develop and prototype a novel compact hyb... more The paper reports the preliminary results of a study to develop and prototype a novel compact hybrid powertrain for a small/medium urban vehicle. The aim is to improve a standard turbocharged gasoline engine's performance by utilizing various energy recovery systems. Most notable is a novel turbocharger with mechanically decoupled compressor and turbine. During operation, the turbine and compressor, which are connected to two different electric machines, contribute a net energy input to the battery pack. The mechanical decoupling also enables both machines to operate close to their maximum efficiency over the expected real operating range. A properly designed engine control unit (ECU) monitors and controls the angular velocities of the two machines separately, eliminating the need for a wastegate valve enabling a net surplus of electrical energy generated by the turbine. The study focuses on the compressor and its electric motor, which are two essential components of the suggested design. The two components must be developed together and their performance curves closely matched due to the extremely high speed required by the design criteria that dictate high power density. The compressor used is a modified Garrett GT12, and the electric motor is a high-speed prototype brushless unit. The design parameters and their impact on the operating ranges of both the compressor and the electric motor are described. After a description of the conceptual and technological issues encountered during the design, the proposed solutions are discussed in detail, with preliminary results reported.