


Politecnico di Torino  
Academic Year 2017/18  
01QHBND Energy storage and trasmission 

Master of sciencelevel of the Bologna process in Energy And Nuclear Engineering  Torino 





Subject fundamentals
Due to a continuous and inevitable depletion of fossil fuels, in addition to the great challenge of global warming, we nowadays witness an increasing interest towards renewable and sustainable energy sources. Among all others, solar energy is regarded to as one of the most promising for substituting traditional energy sources. However, the main problem with solar energy (and many other renewable energies) is its intermittent and unstable nature, which determines an undesired time mismatch between its availability and demand. Energy storage is a key technology to properly address this issue, thus enabling a much more extensive use and exploitation of natural and green energy resources.
In the introductory part of this course, we aim at providing an extensive and uptodate overview of the disparate technology solutions which have been developed so far (both those that are already on the market and the ones that are still under investigations) for storing energy under diverse forms. Afterwards, we will particularly focus on thermal energy storage with a special emphasis on lowtemperature thermal solar energy for civil applications. More precisely, this course, through a series of theoretical lectures, discussion of case studies, numerical exercises in the labs and experimental activities on heat storage aims at providing students with all necessary competencies for properly choosing the storage technology which maximizes the exploitation of a given intermittent energy source. We expect students to gain the essential knowhow and tools for designing, sizing and analyzing (from both energy and cost perspective) the main components of storage plants. 
Expected learning outcomes
First of all, this course aims at providing a wide overview on the different technologies so far developed for addressing the fundamental problem of energy storage, with a special focus on the most effective approaches for storing (lowtemperature) heat.
Thanks to a number of theoretical lectures, the student has the opportunity of learning the basic principles and notions underlying the main components utilized in the energy storage devices. Those lectures will also help students to have a coherent vision of the matter and make an aware use of design tools that are discussed during the course. In fact, we expect students to acquire the ability of a quantitative design of storage systems (mostly sensible, latent and sorption thermal energy storage). Such an ability is essential for helping student in strengthening their problemsolving attitude (a very desirable skill of engineers). All this will be pursued by: 1) Case study discussion; 2) handson sessions during the numerical labs; 3) experiments in the heat storage lab; 4) solution of storage problems suggested by the lecturer (not mandatory). 
Prerequisites / Assumed knowledge
Basic knowledge on heat transfer and applied thermodynamics.

Contents
The course can be subdivided as follows:
Brief overview of the course and a short review of the main heat transfer mechanisms, heat exchangers with and without fins. Brief review of some of the most important relationships in applied thermodynamics. The importance of energy storage. Storage of mechanical energy: Compressed air and pumped hydrostorage plants. Flywheels. Electrochemical batteries. The issue of deep cycling, battery capacity and other main figure of merit of storage systems. Magnetic storage. Supercapacitors. Hydrogen production as an energy storage strategy. Direct and indirect heat storage plants. Materials and plant layout for sensible heat storage. First and second law efficiencies. Optimal size and storage period. Sizing of small sensible systems with water as storage material for solar applications. Common storage tanks. The importance of the temperature stratification. Simple design approaches for rockbeds. Simplified energy and exergy analysis of stratified sensible heat storage. Solar ponds. Numerical examples of sensible storage systems. Classification of the most common materials for latent heat storage applications (organic, inorganic and eutectic). Short discussion on supercooling, segregation and cycling issues. Examples of phasechangematerials (PCM) available on the market. PCM for buildings: A brief discussion on the use of PCM for passive cooling applications. Some analytical and numerical modeling tools for PCM charging and discharging processes. The choice of the optimal PCM material. Numerical examples of latent storage systems. The notion of inversion temperature. Closed and open sorption TES. Main thermodynamic transformations and relations describing sorption phenomena. Isosteric heat and isosteric field for a sorbentsorbate pair. Adsorption isotherms. Discussion of ideal and real sorption heat storage cycles. Simplified models for describing sorption phenomena (DubininAstakhov and Langmuir). Numerical examples of sorption heat storage systems. Brief discussion on nanosuspensions for heat transfer enhancement. A few elements on the energy transfer at the nanoscale. A brief discussion on microencapsulated phasechange materials for heat capacity enhancement. Percolating networks of nanoparticles with high thermal conductivity for heat storage applications. Basic notions on classical molecular dynamics simulations. 
Delivery modes
This course also includes the following activities:

Texts, readings, handouts and other learning resources
All arguments discussed during this course will be covered by the material directly provided by the lecturer. In addition, the interested student can find below a list of References for possible further readings:
 I. Dincer, M.A. Rosen, "Thermal Energy Storage Systems and Applications", John Wiley & Sons, 2nd Edition, 2011.  P. Asinari, E. Chiavazzo, "An Introduction to Multiscale Modeling with Applications", Esculapio, Bologna, 2013.  A. Bejan, "Advanced Engineering Thermodynamic", John Wiley & Sons, 1997.  A. Bejan, A.D. Kraus (Editors), "Heat Transfer Handbook", John Wiley & Sons, 2003.  Matteo Fasano, Masoud Bozorg Bigdeli, Mohammad Rasool Vaziri Sereshk, Eliodoro Chiavazzo, Pietro Asinari, "Thermal transmittance of carbon nanotube networks: Guidelines for novel thermal storage systems and polymeric material of thermal interest", Ren. Sust. Energy Rev. 41, 2015.  Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari, Paolo Decuzzi, "Scaling behaviour for the water transport in nanoconfined geometries", Nature Comm. 4565, 2014.  Chiavazzo E., Asinari P., "Reconstruction and modeling of 3D percolation networks of carbon fillers in a polymer matrix" Int. J. Thermal. Sci. 49, 2010.  Chiavazzo E., Asinari P., "Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?" Nanosc. Res. Lett. 6, 2011. 
Assessment and grading criteria
The examination is oral, but students are also requested to produce a brief essay on one of the numerical activities carried out during the laboratory. In addition, students are free to produce a report on a heat storage plant design. The latter report is completely discretionary. However, only those who will present and discuss, during the oral examination, the report may gain extra 2 points (maximum) for the final mark. Extra mark will depend on the quality of the discretionary report. In the latter, a description of a heat storage plant (preferably freely chosen or suggested by the lecturer), its sizing along with energy, exergy and economic analysis should be included relying upon the notions learned during the course. The minimum score to pass the exam is 18/30. Regardless of the optional report, everyone can potentially get the maximum mark (possibly cum laude). In particular, the examination is intended to assess the achievement of the following objectives:
1. Understanding theoretical basis of the different energy storage and transport technologies. This is pursued through questions during the oral examination; 2. Developing the ability in choosing and designing a technology for energy storage and transport capable of coping with realistic constraints. This is pursued through both questions during the oral examination and the report; 3. Developing the ability in sizing accurately important ancillaries and components in heat storage technologies. This is pursued through the requested essay on the numerical activities. 
