Andrea VITRANO
About

A highly motivated, detail-oriented energy engineer with international experiences; expertise in computational heat transfer and fluid flow; seeking to bring a contribution to exciting research projects.

Currently working as a research engineer on the phenomena of heat transfer and phase transition of superfluid helium in micro-channels in order to predict the thermal behaviour of superconducting magnet coils for particle accelerators and other industrial applications. 

 

 

Experience
2018 - now
Research Engineer - Marie Skłodowska-Curie Action (MSCA) PhD Fellow
CEA, Paris France
  • Modelling and experimental validation of the helium thermo-fluid dynamics under different thermodynamic conditions in micro-channels
2017 - 2018
Research Intern
KTH Royal Institute of Technology, Stockholm, Sweden.
  • Analysis of lifetime consumption and thermo-mechanical conditions of Concentrating Solar Power steam turbines
  • Use of multi-objective optimization
Expertise
Computer skills
Computer skills
Critical thinking
Critical thinking
Network
Network
Presentation
Presentation
Problem solving
Problem solving
Software
Software
Education
2018 - present
PhD in Cryogenic Engineering
CEA, Paris, France.
  • Study of heat and mass transfer in superfluid helium in confined geometries
2016 - 2017
MSc International Thesis Programme
KTH Royal Institute of Technology, Stockholm, Sweden.
  • Validation and start-up optimization of a steam turbine in a Direct Steam Generation Tower Power plant
2015 - 2016
MSc Exchange Programme
Korea Advanced Institute of Science & Technology (KAIST), Daejeon, South Korea
2014 - 2017
Master of Science in Energy and Nuclear Engineering
Politecnico di Torino, Turin, Italy.
2010 - 2014
Bachelor of Science in Energy Engineering
Politecnico di Torino, Turin, Italy
Work on project

Understanding the thermal phenomena that arise in superfluid helium under different thermodynamic conditions in confined geometries and creating a computational model capable of simulating the thermo-fluid behavior of superfluid helium.

	Presentations at the FCC conferences in Amsterdam (2018) and Bruxelles (2019): during a session dedicated to cryogenics applied to particle accelerator technologies.

Photo: Presentations at the FCC conferences in Amsterdam (2018) and Bruxelles (2019): during a session dedicated to cryogenics applied to particle accelerator technologies.

 

 

 

 

 
What is the key question you try to address?

Key objective of my research is to understand the thermal phenomena that arise in superfluid helium in confined geometries. Superfluid helium is a particular state of liquid helium that has remarkable transport properties such as an unmatched ability to transmit heat. This unique state, which appears at a temperature lower than the outer space one, allows helium to be an incredibly efficient coolant. In particular, amongst the engineering applications of superfluid helium, the cooling of magnets plays an important role in the particle accelerators field. In the most advanced particle colliders, the magnets used to bend the particles trajectory are required to be in the superconductive state, at which their electrical resistance vanishes. In order to maintain this state, the magnets must be kept at a really low temperature. The unparalleled characteristics of superfluid helium ensure to meet this requirement.

Nevertheless, the geometrical configuration of superconducting magnets for accelerators creates geometrical confinements that reduce the cooling even with superfluid helium. The electrical insulation of the superconducting cables for example constitutes one of the highest thermal barriers for the cooling process by creating a network of micro-channels. My research aims at acquiring a better understanding of the heat transfer processes in superfluid helium under these conditions and being able to replicate them through a numerical model.

 

 

 

 

Which method tools are you using?

In order to be able to operate with superfluid helium, the experiments need to be performed at cryogenic conditions, namely at really low temperature. For this purpose, I utilize a cryostat, which is a device capable of cooling the helium down by regulating its pressure. The cryostat also maintains these conditions for long periods thanks to thermal insulation layers and vacuum that isolates the experimental environment. This environment allows me to test the thermal behavior of the fluid under different conditions in small channels with sizes from a few millimeters down to micrometers. The important parameter in these experiments is the temperature, which is measured by tiny sensors located along the channel. In particular, it is of great interest the reaction of the helium contained in the channel following heat pulses, which are regulated externally.

For what concerns the numerical work, I have been using a software for fluid dynamics simulations called OpenFOAM. It is an open source tool and, as such, allows me to modify freely the source code to satisfy the particular requirements of the physics of superfluid helium. The solver that I am developing is meant to be as versatile as possible in order to be used to simulate the behavior of helium at any condition for a large number of applications. For instance, in the case of my research topic, this solver will help to improve the cooling system of particle accelerators.

 

 

 

 

 
Can you summarize some of the results of your research?

I have recently performed experiments with superfluid helium in a 1 mm thick channel. Below a picture of the aforementioned cryostat utilized to create the desired environment for the experimental session. Once the conditions were achieved, a heat flux was provided to the helium and its temperature was recorded along the channel.

Image removed.

Moreover, I have developed the numerical model that simulates the behavior of superfluid helium. In order to make sure that this model works in the right way, it is necessary to compare the simulations to a real case. For this purpose, I validated the model against elaborated data from my experiment. In order to do this, the geometry of the channel has to be reproduced via a specific type of software and the conditions of the experiment have to be replicated in the simulation. The results of the comparison can be seen in the following plot, which shows the temperature evolution of the helium inside the channel at different times. The big dots represent the experimental data and the solid lines the simulations. In general, the more they match, the more the model is able to simulate the helium characteristics. In an experiment, there are several instrumental errors that must be taken into account, but the overall comparison is really satisfying and allows me to use this model as a starting point for further improvements. These results have recently been submitted as scientific paper in the proceedings of the 2019 edition of the international Cryogenic Engineering Conference under the title “Transient conjugate heat transfer numerical simulation in superfluid helium”.

In addition, I have developed a numerical model that simulates the behavior of superfluid helium. In order to make sure that this model works in the right way, it is necessary to compare the simulations to a real case. For this purpose, I validated the model against elaborated data from my experiment. In order to do this, the geometry of the channel has to be reproduced via a specific type of software and the conditions of the experiment have to be replicated in the simulation. The results of the comparison can be seen in the following plot, which shows the temperature evolution of the helium inside the channel at different times. The big dots represent the experimental data and the solid lines the simulations. In general, the more they match, the more the model is able to simulate the helium characteristics. In an experiment, there are several instrumental errors that must be taken into account, but the overall comparison is really satisfying and allows me to use this model as a starting point for further improvements. These results have recently been submitted as scientific paper in the proceedings of the 2019 edition of the international Cryogenic Engineering Conference under the title “Transient conjugate heat transfer numerical simulation in superfluid helium". 

Image removed.

 

 

 

 

 

 

 
What are the next steps?

I am going to carry out other experiments with thinner channels in order to understand the effect of the size of the geometry on the behavior of superfluid helium. In addition, new modules representing different states of helium can be implemented into the numerical model. For example, the phase change from superfluid to normal state that helium undergoes when its temperature increases till a certain value is of particular interest. This phase transition is associated to a significant variation in the helium properties. These variations are a big obstacle in the accuracy and stability of the simulations and, hence, they represent a considerable challenge in my project. The phase transition will also be studied experimentally in the next session of tests. The goal will be figuring out what happens to the helium contained inside a thin channel as a consequence of a sudden change of state.

 

 

 

 

 

 
Which can be the applications from your research?

Thermo-fluid dynamics simulations of helium are important in order to improve the performances of a wide variety of technologies. The numerical model I am developing will be particularly suited for cryogenics applications. For instance, one reason that drives my research is related to the improvement of the cryogenic design of particle accelerators such as the Large Hadron Collider at CERN, the European Organization for Nuclear Research. The enhancement of the magnet cooling process in such facilities will reduce the energy consumption and the risk of breakdown and consequent damage of the machines.

During operation of these particle accelerators, it could happen that the magnets exit the superconductive state due to a sudden increase in the magnetic field. When this happens, the electrical resistance of the magnets is restored and the current flowing through the cables generates a huge amount of energy that is released via heat. The extent of this heat is sufficient to vaporize instantly the liquid helium that surrounds the magnets. This boil-off is associated to a generated force that is able to break the magnets. My experiments will help to achieve a clearer view on this mechanism and to design novel configurations to avoid such unpleasant events. However, high-energy physics is not the only application field of my research. Liquid helium is in fact involved in the cooling system of fusion reactors and space-based instruments in satellites, thus in the energy production industry and astronomy.