- Heat Transfer, Sprays, Heat Pipes, Pulsating Heat Pipe, Drop Impact, Spray Impact, and 19 moreBuidling Energy, Flow Boiling, Nanotechnology, superhydrophobic surfaces, SAMs, Thermodynamics, Internal Combustion Engines, Fuels, Fuel Cells, Injectors and Sprays, Hypothermia, Thermo-fluid, Close Circuit Water Loop, Mass, Fluid Dynamics, Computational Fluid Dynamics, Engineering, Mechanical Engineering, Fluid Mechanics, Aerospace Engineering, and Energy efficiency(Buidling Energy, Flow Boiling, Nanotechnology, superhydrophobic surfaces, SAMs, Thermodynamics, Internal Combustion Engines, Fuels, Fuel Cells, Injectors and Sprays, Hypothermia, Thermo-fluid, Close Circuit Water Loop, Mass, Fluid Dynamics, Computational Fluid Dynamics, Engineering, Mechanical Engineering, Fluid Mechanics, Aerospace Engineering, and Energy efficiency)edit
- Marco Marengo, Professor of Thermal Engineering at the University of Brighton, UK. Member of the Space Environment Ad... moreMarco Marengo, Professor of Thermal Engineering at the University of Brighton, UK. Member of the Space Environment Advisory Committee of the UK Space Agency. Visiting Professor at the Laboratoire de Physique des Surfaces et des Interfaces, University of Mons, Belgium, at the University of Toronto and York University in Toronto, Canada. UK permanent representative in the Committee of International Heat Pipe Conference and International Heat Pipe Symposium. Co-director of the International Advanced Course of Liquid Interfaces, Drop and Spray Systems. Member of the Center for Innovation, Technology and Policy Research - IN+, Instituto Superior Técnico, Lisbon, Portugal.(Marco Marengo, Professor of Thermal Engineering at the University of Brighton, UK. Member of the Space Environment Advisory Committee of the UK Space Agency. Visiting Professor at the Laboratoire de Physique des Surfaces et des Interfaces, University of Mons, Belgium, at the University of Toronto and York University in Toronto, Canada. UK permanent representative in the Committee of International Heat Pipe Conference and International Heat Pipe Symposium. Co-director of the International Advanced Course of Liquid Interfaces, Drop and Spray Systems. Member of the Center for Innovation, Technology and Policy Research - IN+, Instituto Superior Técnico, Lisbon, Portugal.)edit
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... 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...
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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... 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...
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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,... 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...
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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... 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...
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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... 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...
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Book of Abstractsinfo:eu-repo/semantics/publishe
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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... 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...
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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... 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...
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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... 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...
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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... 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
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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... 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...
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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... 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...
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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... 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 ...
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Encapsulation of solid particles and liquid agents in a liquid shell is of exceptional interest in biotechnological, chemical and pharmaceutical fields such as personalized medicine, fluidized catalytic cracking, wire fabrication,... more
Encapsulation of solid particles and liquid agents in a liquid shell is of exceptional interest in biotechnological, chemical and pharmaceutical fields such as personalized medicine, fluidized catalytic cracking, wire fabrication, catalytic reactions. Looking at the interaction between liquid drop and solid particles, we can study the special, ideal case of spherical drops impacting solid spheres, in order to understand the basic phenomena and the effect of the physical variables on the spreading behavior. Considering the importance of dynamics of drop-particle collision, which directly affects the quality of film deposition during encapsulation, various aspects of drop impact on dry solid spherical surfaces are still lacking in the existing literature. The cases are studied with a 3D level-set method implemented in a standard finite-element-based solver platform. The impact Weber number, the size ratio (ratio of spherical particle diameter to droplet diameter), and the surface cont...
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Phase change heat transfer within microchannels is considered one of the most promising cooling methods for the efficient cooling of high-performance electronic devices. However, there are still fundamental parameters, such as the effect... more
Phase change heat transfer within microchannels is considered one of the most promising cooling methods for the efficient cooling of high-performance electronic devices. However, there are still fundamental parameters, such as the effect of channel hydraulic diameter Dh whose effects on fluid flow and heat transfer characteristics are not clearly defined yet. The objective of the present work is to numerically investigate the first transient flow boiling characteristics from the bubble inception up to the first stages of the flow boiling regime development, in rectangular microchannels of varying hydraulic diameters, utilising an enhanced custom VOF-based solver. The solver accounts for conjugate heat transfer effects, implemented in OpenFOAM and validated in the literature through experimental results and analytical solutions. The numerical study was conducted through two different sets of simulations. In the first set, flow boiling characteristics in four single microchannels of D...
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Liquid penetration analysis in porous media is of great importance in a wide range of applications such as ink jet printing technology, painting and textile design. This article presents an investigation of droplet impingement onto... more
Liquid penetration analysis in porous media is of great importance in a wide range of applications such as ink jet printing technology, painting and textile design. This article presents an investigation of droplet impingement onto metallic meshes, aiming to provide insights by identifying and quantifying impact characteristics that are difficult to measure experimentally. For this purpose, an enhanced Volume-Of-Fluid (VOF) numerical simulation framework is utilised, previously developed in the general context of the OpenFOAM CFD Toolbox. Droplet impacts on metallic meshes are performed both experimentally and numerically with satisfactory degree of agreement. From the experimental investigation three main outcomes are observed—deposition, partial imbibition, and penetration. The penetration into suspended meshes leads to spectacular multiple jetting below the mesh. A higher amount of liquid penetration is linked to higher impact velocity, lower viscosity and larger pore size dimens...
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The spreading and rebound patterns of low-viscous droplets upon impacting spherical solid surfaces are investigated numerically. The studied cases consider a droplet impinging onto hydrophobic and superhydrophobic surfaces with various... more
The spreading and rebound patterns of low-viscous droplets upon impacting spherical solid surfaces are investigated numerically. The studied cases consider a droplet impinging onto hydrophobic and superhydrophobic surfaces with various parameters varied throughout the study, and their effects on the postimpingement behavior are discussed. These parameters include impact Weber number (through varying the surface tension and impingement velocity), the size ratio of the droplet to the solid surface, and the surface contact angle. According to the findings, the maximum spreading diameter increases with the impact velocity, with an increase of the sphere diameter, with a lower surface wettability, and with a lower surface tension. Typical outcomes of the impact include (1) complete rebound, (2) splash, and (3) a final deposition stage after a series of spreading and recoiling phases. Finally, a novel, practical model is proposed, which can reasonably predict the maximum deformation of lo...
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The present investigation aims to devise a thermal management system (TMS) for electric vehicles able to improve on limitations like charging time and all-electric range, together with the safety and environmental impact of the chosen... more
The present investigation aims to devise a thermal management system (TMS) for electric vehicles able to improve on limitations like charging time and all-electric range, together with the safety and environmental impact of the chosen thermal medium. A research gap is identified, as focus is often on addressing system thermal performance without considering that the thermal medium must not only provide suitable performances, but also must not add risks to both passengers and the environment. Thus, this work proposes an innovative cooling system including graphite sheets and a Loop Heat Pipe, filled with Novec™ 649 as working fluid, due to its exceptional environmental properties (GWP = 1 − ODP = 0) and safety features (non-flammable, non-toxic, dielectric). A three-cell module experimental demonstrator was built to compare temperatures when the proposed TMS is run with Novec™ 649 and ethanol. Results of testing over a bespoke fast charge driving cycle show that Novec™ 649 gave a fas...
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... Tel. +39 3315714238; stefano.zinna@uniheat.it Marco Marengo University of Bergamo, Microfluidic Lab viale Marconi 5, 24044 Dalmine (BG), Italy Marco Molina Carlo Gavazzi Space Via Gallarate 150, 20151 Milano, Italy Abstract ...
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ABSTRACT