Marco Marengo | University of Brighton (original) (raw)
Papers by Marco Marengo
Energies, 2022
Owing to their simple construction, cost effectiveness, and high thermal efficiency, pulsating he... more Owing to their simple construction, cost effectiveness, and high thermal efficiency, pulsating heat pipes (PHPs) are growing in popularity as cooling devices for electronic equipment. While PHPs can be very resilient as passive cooling systems, their operation relies on the establishment and persistence of slug/plug flow as the dominant flow regime. It is, therefore, paramount to predict the flow regime accurately as a function of various operating parameters and design geometry. Flow pattern maps that capture flow regimes as a function of nondimensional numbers (e.g., Froude, Weber, and Bond numbers) have been proposed in the literature. However, the prediction of flow patterns based on deterministic models is a challenging task that relies on the ability of explaining the very complex underlying phenomena or the ability to measure parameters, such as the bubble acceleration, which are very difficult to know beforehand. In contrast, machine learning algorithms require limited a pri...
2017 IEEE SENSORS, 2017
Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced gr... more Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced graphene. The main benefits arise from peculiar electrical, thermal and mechanical performances of the material thus obtained, along with a cheap and simple fabrication process. The temperature sensor is a negative temperature coefficient thermistor with nonlinear response typical of semi-metals. The thermistor shows a 4% decrease of the resistance in a temperature range of 20-60 °C. The flow sensor exploits the piezoresistive properties of laserinduced graphene and can be used both in gaseous and liquid media thanks to a protective polydimethylsiloxane coating. Main characteristics are ultra-fast response and versatility in design offered by the laser technology.
Energies, 2020
In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the... more In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the concept of employing oscillating heat pipes (OHPs) in an abrasive-milling tool is proposed. A single-loop OHP (SLOHP) is positioned on the plane parallel to the rotational axis of the tool. In this case, centrifugal accelerations do not segregate the fluid between the evaporator and condenser. The experimental investigation is conducted to study the effects of centrifugal acceleration (0–738 m/s2), heat flux (9100–31,850 W/m2) and working fluids (methanol, acetone and water) on the thermal performance. Results show that the centrifugal acceleration has a positive influence on the thermal performance of the axial-rotating SLOHP when filled with acetone or methanol. As for water, with the increase of centrifugal acceleration, the heat transfer performance first increases and then decreases. The thermal performance enhances for higher heat flux rises for all the fluids. The flow inside the...
Journal of Heat Transfer, 2019
A low-cost, flexible pulsating heat pipe (PHP) was built in a composite polypropylene sheet consi... more A low-cost, flexible pulsating heat pipe (PHP) was built in a composite polypropylene sheet consisting of three layers joint together by selective laser welding, to address the demand of heat transfer devices characterized by low weight, small unit thickness, low cost, and high mechanical flexibility. A thin, flexible, and lightweight heat pipe is advantageous for various aerospace, aircraft, and portable electronic applications where the device weight, and its mechanical flexibility are essential. The concept is to sandwich a serpentine channel, cut out in a polypropylene sheet and containing a self-propelled mixture of a working fluid with its vapor, between two transparent sheets of the same material; this results into a thin, flat enclosure with parallel channels hence the name “pulsating heat stripes” (PHS). The transient and steady-state thermal response of the device was characterized for different heat input levels and different configurations, either straight or bent at dif...
Langmuir : the ACS journal of surfaces and colloids, Jun 26, 2016
It is well known that a superhydrophobic surface may not be able to repel impacting droplets due ... more It is well known that a superhydrophobic surface may not be able to repel impacting droplets due to the so-called Cassie-to-Wenzel transition. It has been proven that a critical value of the receding contact angle (θR) exists for the complete rebound of water, recently experimentally measured to be 100° for a large range of impact velocities. On the contrary, in the present work, no rebound was observed when low surface tension liquids such as hexadecane (σ = 27.5 mN/m at 25°C) are concerned, even for very low impact velocities and very high values of θR and low contact angle hysteresis. Therefore, the critical threshold of θR ≈ 100° does not sound acceptable for all liquids and for all the hydrophobic surfaces. For the same Weber numbers a Cassie-to-Wenzel state transition occurs after the impact due to the easier penetration of low surface tension fluids in the surface structure. Hence a criterion for drop rebound of low surface tension liquids must consider not only the contact a...
Advances in colloid and interface science, 2014
In this study,a novel numerical implementation for the adhesion of liquid droplets impacting norm... more In this study,a novel numerical implementation for the adhesion of liquid droplets impacting normally on solid dry surfaces is presented. The advantage of this new approach, compared to the majority of existing models, is that the dynamic contact angle forming during the surface wetting process is not inserted as a boundary condition, but is derived implicitly by the induced fluid flow characteristics (interface shape) and the adhesion physics of the gas-liquid-surface interface (triple line), starting only from the advancing and receding equilibrium contact angles. These angles are required in order to define the wetting properties of liquid phases when interacting with a solid surface. The physical model is implemented as a source term in the momentum equation of a Navier-Stokes CFD flow solver as an "adhesion-like" force which acts at the triple-phase contact line as a result of capillary interactions between the liquid drop and the solid substrate. The numerical simula...
Book of Abstractsinfo:eu-repo/semantics/publishe
This work defines a methodology aimed at the creation of a simplified energy model able to simula... more This work defines a methodology aimed at the creation of a simplified energy model able to simulate a residential building with a reasonable workload. The simulation results should have a sufficient accuracy at any stage of a building design, by exploiting the benefits of a modular approach with increasing detail rendition. The idea is to verify the accuracy of the simulations comparing different methodologies, from stationary simulations, using a Italian software called TERMUS, to more sophisticated, even if standard, dynamic simulations, using TRNSYS. Such comparisons have already been carried out in the past in different papers, but a thorough analysis of the envelope-plant system using progressive simplification steps has not yet been done, especially for a residential test case in an on-going retrofit process. The results indicate that with the proper simplification steps, shown in the analysis, the accuracy in terms of energy needs and power curves is very high (the difference...
A Pulsating Heat Pipe specifically designed to be hosted on board the Heat Transfer Host of the I... more A Pulsating Heat Pipe specifically designed to be hosted on board the Heat Transfer Host of the International Space Station is tested in hyper-gravity and microgravity during Parabolic Flights. The device is realized bending an annealed aluminium tube with an inner diameter of 3 mm. The geometry is a three-dimensional closed loop with 14 turns. The external temperatures of the device are measured in the adiabatic zone with a high-speed infrared camera, recording images at 50 frames per second and with a spatial resolution of 1280x1024 pixel. The images are thereafter post-processed and utilized to extrapolate space and time-varying local heat fluxes on the tube internal surface in contact with the fluid, solving the inverse heat conduction problem in the pipe wall. It is found that the local heat flux can reach values up to 10 kW/m during the start-up of the device in weightlessness. These results point out that in this dynamic thermofluidic system, the temperature difference betwee...
The paper stems from the benefits of the application of energy analysis in the early-stage buildi... more The paper stems from the benefits of the application of energy analysis in the early-stage building design combined with the difficulties that prevent this integration due to the complexity of the needed simulations. The most common solution to overtake this obstacle is to simplify the building energy model, but not enough attention is paid to understand or predict the consequences of this action. The paper focuses on discussing the difference in results evaluated comparing the simulation of a detailed building model, based on all information available on the building during operation, and a simplified one, suitable for the application in early stage design. This result is achieved by defining a methodology, which consists in developing a simplification protocol and applying it to a suitable number of case studies starting from a detailed model and ending in the simplified one after the application of said protocol. The protocol is based on the use of EnergyPlus software both to dev...
1 Università degli Studi di Bergamo, Dept. of Eng. and App. Science, Viale Marconi 5, 24044 Dalmi... more 1 Università degli Studi di Bergamo, Dept. of Eng. and App. Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of Brighton, School of Computing, Eng. and Maths, Lewes Road, BN2 4GJ, Brighton, UK, miriam.manzoni@unibg.it 2 Federal University of Santa Catarina, Mech. Eng. Dept., Bairro Trindade 88040-970 Florianópolis (SC), Brazil, tiago@labtucal.ufsc.br 3 Federal University of Santa Catarina, Mech. Eng. Dept., Bairro Trindade 88040-970 Florianópolis (SC), Brazil, marcia.mantelli@ufsc.br 4 Cleanergy, Theres Svenssons gata 15, 417 55 Göteborg, Sweden, per.eskilson@cleanergy.com 5 Università degli Studi di Bergamo, Dept. of Eng. and App. Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of Brighton, School of Computing, Eng. and Maths, Lewes Road, BN2 4GJ, Brighton, UK, m.marengo@brighton.ac.uk
This work presents the creation of a dynamic energy model able to simulate, with a reasonable wor... more This work presents the creation of a dynamic energy model able to simulate, with a reasonable workload, a very large number of integrated building-plant systems with different scales and resolutions, in order to have a design support for architects and designers, reducing their modeling effort and errors. The model includes the dynamic simulation of the building envelope, all the heating plant subsystems, and all the plant components relating to the production of domestic hot water, the latter with possible solar thermal integration. Starting from a detailed model created with the calculation engine Trnsys, the paper explores simplifications that can considerably reduce the number of necessary inputs for the simulations, thus minimizing the modeling, implementation and simulation runtime of the model, while still maintaining an acceptable degree of accuracy with respect to the computational results and real energy consumptions. The model is benchmarked by means of a case study compr...
The paper introduces a newly designed dynamic building energy simulation screening tool to help i... more The paper introduces a newly designed dynamic building energy simulation screening tool to help integrate the use of advanced simulation techniques to early stage building design and feasibility studies. The tool will help the design process to move toward an integrated design approach, including energy analyses and expertise from the first stages of design when time constraints and information requirements are still a hindrance for the use of other existing simulation tools. The paper focus on the integration of the user input and output interfaces and automatic model generation algorithms while referring to previously existing papers in term of model definition, case studies and validation. The tool is able to simulate building energy performances starting from a limited number of inputs received through a specifically designed user interface supported by databases and suggested values. Based on those inputs, a simplified building model is generated and simulated in EnergyPlus and...
1 Università di Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), ... more 1 Università di Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of Brighton, School of Computing, Eng. and Maths, Lewes Road, BN2 4GJ, Brighton, UK, miriam.manzoni@unibg.it 2 Università di Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), Italy, mauro.mameli@unibg.it 3 Technological Education Institute of Piraeus, Thivon 250, Egaleo 122 44, Greece, sotiris.andromidas@gmail.com 4 Politecnico di Milano, Maths Dept., Piazza Leonardo da Vinci 32, 20133 Milano, Italy, carlo.defalco@polimi.it 5 Politecnico di Milano, Energy Dept., Via Lambruschini 4A, 20158 Milano, Italy, lucio.araneo@polimi.it 6 Università di Pisa, DESTEC, Largo Lazzarino 2, 56122 Pisa, Italy, sauro.filippeschi@den.unipi.it Technological Education Institute of Piraeus, Thivon 250, Egaleo 122 44, Greece, ksnikas@teipir.gr 8 Università di of Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of ...
A Closed Loop Pulsating Heat Pipe made of a copper tube (1.1mm/2mm I.D./O.D.) and filled with FC-... more A Closed Loop Pulsating Heat Pipe made of a copper tube (1.1mm/2mm I.D./O.D.) and filled with FC-72 has been tested on the Large Diameter Centrifuge (LDC) of the European Space Agency in Noordwijk at different hypergravity levels up to 20g, different heat input levels and different orientations with respect to the gravity direction (vertical bottom heated and horizontal position). Results shows that both in the horizontal and vertical orientation the device operation depends on the combined effect of gravity and heat input level. For the horizontal orientation, fluid stratification and the consequent thermal crisis occur at different acceleration levels depending also on the heat input power level and on the heating/gravity history. During the vertical operation the PHP thermal performance is slightly enhanced by the lower hyper-gravity levels (up to 3g at 50W, up to 4g at 70W and up to 6g at 100W) while two different local thermal crisis affect the PHP thermal behavior with the higher acceleration levels.
Journal of Engineering and Architecture, 2015
The present paper stems from the benefits of the application of energy analysis in the early-stag... more The present paper stems from the benefits of the application of energy analysis in the early-stage building design combined with the difficulties that prevent this integration. The most common solution is to simplify the building energy model, although not enough attention is paid to understand the consequences of this action. The paper focuses on evaluating the impact of various building model simplifications on the outputs of the dynamic energy simulations. Three different case studies, featuring large non-residential buildings, are discussed in this paper. Differences in results are discussed in term of total heating and cooling energy loads for each simplification. Lastly the total differences between a fully simplified model and the corresponding detailed models are discussed more in detail.
World Congress on Momentum, Heat and Mass Transfer
A numerical investigation on the effect of wettability characteristics on a single bubble growth ... more A numerical investigation on the effect of wettability characteristics on a single bubble growth during saturated flow boiling conditions within a microchannel, is conducted in the present paper. The numerical simulations are conducted with the open-source toolbox OpenFOAM, utilising a user-enhanced Volume OF Fluid (VOF) solver. The proposed solver enhancements involve a treatment for spurious velocities dampening (a well-known defect of VOF methods), an improved dynamic contact angle treatment to accurately account for wettability effects as well as the implementation of a phase-change model in the fluid domain, accounting for conjugate heattransfer with a solid domain. The predictions of the simulations show that the local Nusselt number (Nu) is more depended on wettability characteristics for low heat fluxes, and less dependent on higher heat fluxes. In more detail, it seems that the local, instantaneous heat transfer coefficient is higher for super-hydrophilic cases in comparison to hydrophilic. However, as the applied heat flux increases, hydrophilic and super-hydrophilic cases show a similar heat transfer enhancement with respect to the single-phase heat transfer in the considered micro-channel. Finally, superhydrophobic cases, show lower heat transfer performance with respect to the single-phase case. This is due to the fact that a vapour blanket is rapidly formed immediately after the nucleation, acting as an insulator of the heated solid surface.
Energies, 2022
Owing to their simple construction, cost effectiveness, and high thermal efficiency, pulsating he... more Owing to their simple construction, cost effectiveness, and high thermal efficiency, pulsating heat pipes (PHPs) are growing in popularity as cooling devices for electronic equipment. While PHPs can be very resilient as passive cooling systems, their operation relies on the establishment and persistence of slug/plug flow as the dominant flow regime. It is, therefore, paramount to predict the flow regime accurately as a function of various operating parameters and design geometry. Flow pattern maps that capture flow regimes as a function of nondimensional numbers (e.g., Froude, Weber, and Bond numbers) have been proposed in the literature. However, the prediction of flow patterns based on deterministic models is a challenging task that relies on the ability of explaining the very complex underlying phenomena or the ability to measure parameters, such as the bubble acceleration, which are very difficult to know beforehand. In contrast, machine learning algorithms require limited a pri...
2017 IEEE SENSORS, 2017
Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced gr... more Herein we present a flexible temperature sensor and a flow speed sensor based on laser-induced graphene. The main benefits arise from peculiar electrical, thermal and mechanical performances of the material thus obtained, along with a cheap and simple fabrication process. The temperature sensor is a negative temperature coefficient thermistor with nonlinear response typical of semi-metals. The thermistor shows a 4% decrease of the resistance in a temperature range of 20-60 °C. The flow sensor exploits the piezoresistive properties of laserinduced graphene and can be used both in gaseous and liquid media thanks to a protective polydimethylsiloxane coating. Main characteristics are ultra-fast response and versatility in design offered by the laser technology.
Energies, 2020
In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the... more In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the concept of employing oscillating heat pipes (OHPs) in an abrasive-milling tool is proposed. A single-loop OHP (SLOHP) is positioned on the plane parallel to the rotational axis of the tool. In this case, centrifugal accelerations do not segregate the fluid between the evaporator and condenser. The experimental investigation is conducted to study the effects of centrifugal acceleration (0–738 m/s2), heat flux (9100–31,850 W/m2) and working fluids (methanol, acetone and water) on the thermal performance. Results show that the centrifugal acceleration has a positive influence on the thermal performance of the axial-rotating SLOHP when filled with acetone or methanol. As for water, with the increase of centrifugal acceleration, the heat transfer performance first increases and then decreases. The thermal performance enhances for higher heat flux rises for all the fluids. The flow inside the...
Journal of Heat Transfer, 2019
A low-cost, flexible pulsating heat pipe (PHP) was built in a composite polypropylene sheet consi... more A low-cost, flexible pulsating heat pipe (PHP) was built in a composite polypropylene sheet consisting of three layers joint together by selective laser welding, to address the demand of heat transfer devices characterized by low weight, small unit thickness, low cost, and high mechanical flexibility. A thin, flexible, and lightweight heat pipe is advantageous for various aerospace, aircraft, and portable electronic applications where the device weight, and its mechanical flexibility are essential. The concept is to sandwich a serpentine channel, cut out in a polypropylene sheet and containing a self-propelled mixture of a working fluid with its vapor, between two transparent sheets of the same material; this results into a thin, flat enclosure with parallel channels hence the name “pulsating heat stripes” (PHS). The transient and steady-state thermal response of the device was characterized for different heat input levels and different configurations, either straight or bent at dif...
Langmuir : the ACS journal of surfaces and colloids, Jun 26, 2016
It is well known that a superhydrophobic surface may not be able to repel impacting droplets due ... more It is well known that a superhydrophobic surface may not be able to repel impacting droplets due to the so-called Cassie-to-Wenzel transition. It has been proven that a critical value of the receding contact angle (θR) exists for the complete rebound of water, recently experimentally measured to be 100° for a large range of impact velocities. On the contrary, in the present work, no rebound was observed when low surface tension liquids such as hexadecane (σ = 27.5 mN/m at 25°C) are concerned, even for very low impact velocities and very high values of θR and low contact angle hysteresis. Therefore, the critical threshold of θR ≈ 100° does not sound acceptable for all liquids and for all the hydrophobic surfaces. For the same Weber numbers a Cassie-to-Wenzel state transition occurs after the impact due to the easier penetration of low surface tension fluids in the surface structure. Hence a criterion for drop rebound of low surface tension liquids must consider not only the contact a...
Advances in colloid and interface science, 2014
In this study,a novel numerical implementation for the adhesion of liquid droplets impacting norm... more In this study,a novel numerical implementation for the adhesion of liquid droplets impacting normally on solid dry surfaces is presented. The advantage of this new approach, compared to the majority of existing models, is that the dynamic contact angle forming during the surface wetting process is not inserted as a boundary condition, but is derived implicitly by the induced fluid flow characteristics (interface shape) and the adhesion physics of the gas-liquid-surface interface (triple line), starting only from the advancing and receding equilibrium contact angles. These angles are required in order to define the wetting properties of liquid phases when interacting with a solid surface. The physical model is implemented as a source term in the momentum equation of a Navier-Stokes CFD flow solver as an "adhesion-like" force which acts at the triple-phase contact line as a result of capillary interactions between the liquid drop and the solid substrate. The numerical simula...
Book of Abstractsinfo:eu-repo/semantics/publishe
This work defines a methodology aimed at the creation of a simplified energy model able to simula... more This work defines a methodology aimed at the creation of a simplified energy model able to simulate a residential building with a reasonable workload. The simulation results should have a sufficient accuracy at any stage of a building design, by exploiting the benefits of a modular approach with increasing detail rendition. The idea is to verify the accuracy of the simulations comparing different methodologies, from stationary simulations, using a Italian software called TERMUS, to more sophisticated, even if standard, dynamic simulations, using TRNSYS. Such comparisons have already been carried out in the past in different papers, but a thorough analysis of the envelope-plant system using progressive simplification steps has not yet been done, especially for a residential test case in an on-going retrofit process. The results indicate that with the proper simplification steps, shown in the analysis, the accuracy in terms of energy needs and power curves is very high (the difference...
A Pulsating Heat Pipe specifically designed to be hosted on board the Heat Transfer Host of the I... more A Pulsating Heat Pipe specifically designed to be hosted on board the Heat Transfer Host of the International Space Station is tested in hyper-gravity and microgravity during Parabolic Flights. The device is realized bending an annealed aluminium tube with an inner diameter of 3 mm. The geometry is a three-dimensional closed loop with 14 turns. The external temperatures of the device are measured in the adiabatic zone with a high-speed infrared camera, recording images at 50 frames per second and with a spatial resolution of 1280x1024 pixel. The images are thereafter post-processed and utilized to extrapolate space and time-varying local heat fluxes on the tube internal surface in contact with the fluid, solving the inverse heat conduction problem in the pipe wall. It is found that the local heat flux can reach values up to 10 kW/m during the start-up of the device in weightlessness. These results point out that in this dynamic thermofluidic system, the temperature difference betwee...
The paper stems from the benefits of the application of energy analysis in the early-stage buildi... more The paper stems from the benefits of the application of energy analysis in the early-stage building design combined with the difficulties that prevent this integration due to the complexity of the needed simulations. The most common solution to overtake this obstacle is to simplify the building energy model, but not enough attention is paid to understand or predict the consequences of this action. The paper focuses on discussing the difference in results evaluated comparing the simulation of a detailed building model, based on all information available on the building during operation, and a simplified one, suitable for the application in early stage design. This result is achieved by defining a methodology, which consists in developing a simplification protocol and applying it to a suitable number of case studies starting from a detailed model and ending in the simplified one after the application of said protocol. The protocol is based on the use of EnergyPlus software both to dev...
1 Università degli Studi di Bergamo, Dept. of Eng. and App. Science, Viale Marconi 5, 24044 Dalmi... more 1 Università degli Studi di Bergamo, Dept. of Eng. and App. Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of Brighton, School of Computing, Eng. and Maths, Lewes Road, BN2 4GJ, Brighton, UK, miriam.manzoni@unibg.it 2 Federal University of Santa Catarina, Mech. Eng. Dept., Bairro Trindade 88040-970 Florianópolis (SC), Brazil, tiago@labtucal.ufsc.br 3 Federal University of Santa Catarina, Mech. Eng. Dept., Bairro Trindade 88040-970 Florianópolis (SC), Brazil, marcia.mantelli@ufsc.br 4 Cleanergy, Theres Svenssons gata 15, 417 55 Göteborg, Sweden, per.eskilson@cleanergy.com 5 Università degli Studi di Bergamo, Dept. of Eng. and App. Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of Brighton, School of Computing, Eng. and Maths, Lewes Road, BN2 4GJ, Brighton, UK, m.marengo@brighton.ac.uk
This work presents the creation of a dynamic energy model able to simulate, with a reasonable wor... more This work presents the creation of a dynamic energy model able to simulate, with a reasonable workload, a very large number of integrated building-plant systems with different scales and resolutions, in order to have a design support for architects and designers, reducing their modeling effort and errors. The model includes the dynamic simulation of the building envelope, all the heating plant subsystems, and all the plant components relating to the production of domestic hot water, the latter with possible solar thermal integration. Starting from a detailed model created with the calculation engine Trnsys, the paper explores simplifications that can considerably reduce the number of necessary inputs for the simulations, thus minimizing the modeling, implementation and simulation runtime of the model, while still maintaining an acceptable degree of accuracy with respect to the computational results and real energy consumptions. The model is benchmarked by means of a case study compr...
The paper introduces a newly designed dynamic building energy simulation screening tool to help i... more The paper introduces a newly designed dynamic building energy simulation screening tool to help integrate the use of advanced simulation techniques to early stage building design and feasibility studies. The tool will help the design process to move toward an integrated design approach, including energy analyses and expertise from the first stages of design when time constraints and information requirements are still a hindrance for the use of other existing simulation tools. The paper focus on the integration of the user input and output interfaces and automatic model generation algorithms while referring to previously existing papers in term of model definition, case studies and validation. The tool is able to simulate building energy performances starting from a limited number of inputs received through a specifically designed user interface supported by databases and suggested values. Based on those inputs, a simplified building model is generated and simulated in EnergyPlus and...
1 Università di Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), ... more 1 Università di Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of Brighton, School of Computing, Eng. and Maths, Lewes Road, BN2 4GJ, Brighton, UK, miriam.manzoni@unibg.it 2 Università di Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), Italy, mauro.mameli@unibg.it 3 Technological Education Institute of Piraeus, Thivon 250, Egaleo 122 44, Greece, sotiris.andromidas@gmail.com 4 Politecnico di Milano, Maths Dept., Piazza Leonardo da Vinci 32, 20133 Milano, Italy, carlo.defalco@polimi.it 5 Politecnico di Milano, Energy Dept., Via Lambruschini 4A, 20158 Milano, Italy, lucio.araneo@polimi.it 6 Università di Pisa, DESTEC, Largo Lazzarino 2, 56122 Pisa, Italy, sauro.filippeschi@den.unipi.it Technological Education Institute of Piraeus, Thivon 250, Egaleo 122 44, Greece, ksnikas@teipir.gr 8 Università di of Bergamo, Dept. of Eng. and Applied Science, Viale Marconi 5, 24044 Dalmine (BG), Italy; University of ...
A Closed Loop Pulsating Heat Pipe made of a copper tube (1.1mm/2mm I.D./O.D.) and filled with FC-... more A Closed Loop Pulsating Heat Pipe made of a copper tube (1.1mm/2mm I.D./O.D.) and filled with FC-72 has been tested on the Large Diameter Centrifuge (LDC) of the European Space Agency in Noordwijk at different hypergravity levels up to 20g, different heat input levels and different orientations with respect to the gravity direction (vertical bottom heated and horizontal position). Results shows that both in the horizontal and vertical orientation the device operation depends on the combined effect of gravity and heat input level. For the horizontal orientation, fluid stratification and the consequent thermal crisis occur at different acceleration levels depending also on the heat input power level and on the heating/gravity history. During the vertical operation the PHP thermal performance is slightly enhanced by the lower hyper-gravity levels (up to 3g at 50W, up to 4g at 70W and up to 6g at 100W) while two different local thermal crisis affect the PHP thermal behavior with the higher acceleration levels.
Journal of Engineering and Architecture, 2015
The present paper stems from the benefits of the application of energy analysis in the early-stag... more The present paper stems from the benefits of the application of energy analysis in the early-stage building design combined with the difficulties that prevent this integration. The most common solution is to simplify the building energy model, although not enough attention is paid to understand the consequences of this action. The paper focuses on evaluating the impact of various building model simplifications on the outputs of the dynamic energy simulations. Three different case studies, featuring large non-residential buildings, are discussed in this paper. Differences in results are discussed in term of total heating and cooling energy loads for each simplification. Lastly the total differences between a fully simplified model and the corresponding detailed models are discussed more in detail.
World Congress on Momentum, Heat and Mass Transfer
A numerical investigation on the effect of wettability characteristics on a single bubble growth ... more A numerical investigation on the effect of wettability characteristics on a single bubble growth during saturated flow boiling conditions within a microchannel, is conducted in the present paper. The numerical simulations are conducted with the open-source toolbox OpenFOAM, utilising a user-enhanced Volume OF Fluid (VOF) solver. The proposed solver enhancements involve a treatment for spurious velocities dampening (a well-known defect of VOF methods), an improved dynamic contact angle treatment to accurately account for wettability effects as well as the implementation of a phase-change model in the fluid domain, accounting for conjugate heattransfer with a solid domain. The predictions of the simulations show that the local Nusselt number (Nu) is more depended on wettability characteristics for low heat fluxes, and less dependent on higher heat fluxes. In more detail, it seems that the local, instantaneous heat transfer coefficient is higher for super-hydrophilic cases in comparison to hydrophilic. However, as the applied heat flux increases, hydrophilic and super-hydrophilic cases show a similar heat transfer enhancement with respect to the single-phase heat transfer in the considered micro-channel. Finally, superhydrophobic cases, show lower heat transfer performance with respect to the single-phase case. This is due to the fact that a vapour blanket is rapidly formed immediately after the nucleation, acting as an insulator of the heated solid surface.