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International Conference on Innovative Applied Energy    

E-Proceedings ISBN: 978-1-912532-05-6

St Cross College, University of Oxford, United Kingdom

  


 

Nanotechnology for thermal engineering: Challenges and perpectives of state-of-the-art solutions

 


 

Matteo Fasano, Annalisa Cardellini, Matteo Morciano, Matteo Alberghini, Pietro Asinari and Eliodoro Chiavazzo

Politecnico di Torino – Department of Energy, Corso Duca Degli Abruzzi, 2410129 Torino, Italy

 

Paper Abstract

In the last decades, the use of nanotechnology solutions has attracted a lot of attention, among others, in the field of Thermal Engineering - TE. Despite such an enthusiasm, it is fair to say that the potential of nanotechnology has not been fully exploited yet (as far as TE is concerned). The reasons for this untapped opportunity, we believe, should be carefully analized in order to answer the following question: Does nanotechnology really allow us to significantly outperform traditional or more established TE technology? If so, under which circumstances and at what cost? To this end, we discuss a couple of case studies of interest in applied energy (and TE).

First, we focus on nanofluids (i.e. suspensions of nanoparticles in liquids) which have been proposed for important applied energy problems. Nanofluids have been thoroughly investigated as they are expected to improve convective heat transfer and solar energy collection due to enhanced properties of typical base fluids.

In the published literature, the macroscopic properties of nanofluids and nanocomposites are predicted by semi-empirical correlations, that are unfit to describe complex phenomena such as particle aggregation. Unlike other related works, we here discuss a multi-scale model capable of comprehensively describing nanofluids using a novel bottom-up approach providing effective properties starting from fundamental principles (i.e. molecular and Brownian dynamics). Our approach paves the way to predictive models for nanofluids. However, it is not challenge free as it is computationally very intensive and future studies shall focus on improving the method efficiency.

Moreover, we present an experimental study where a novel biocompatible nanofluid for the volumetric solar energy collection is optically characterized and tested under operating condition of engineering relevance. We show some advantages in terms of efficiency as compared to both traditional solutions (i.e. optically selective adsorbing coatings) and more advanced nanofluids (e.g. based on carbon nanohorn suspensions). A lab scale prototype was designed to assess the properties of the nanofluid as volumetric solar receiver. The efficiency of the prototype is evaluated both under solar simulator and in-field, and a suitable comparison with a conventional set-up shows an enhancement of the energy performances of the nanofluid-based volumetric receiver up to 20%. Here, challenges are related to the stability of the biocompatible nanofluid and higher level of complexity.

As a second case study, we analize low-cost nanotech solutions for exploiting solar energy in steam generation (with efficiency of 85% or higher) and sustainable water treatment. Unlike many related work, here we show that the benefit of advanced nanotech solutions is still debatable and unclear.

Finally, we focus on titania (TiO2) based micro-suspensions for municipal water treatment. Here, the suspension exploits the UV part of sunlight spectrum to drastically reduce the bacteria content in the treated water. Performances of both conventional (homogeneously distributed particles) and unconventional (heterogeneously distributed particles) suspensions are presented and compared on the basis of treated water productivity and quality (bacteria content). We demonstrate that optimal configurations can deliver (partially) purified water at a cost of less than 3 Euro per cubic meter. 

Paper Keywords
Nanofluids, nano-composites, thermal solar energy, thermal engineering.
Corresponding author Biography
Dr. Eliodoro Chiavazzo is associate professor at the Energy Department of Politecnico di Torino, where he is co-founder and co-director (with P. Asinari) of the multi-Scale ModeLing Laboratory - SMaLL. Main research interest: heat and mass transfer phenomena, nanotechnology for thermal engineering. Since 2005, Dr. Chiavazzo is (co-)author of over 60 international publications and 5 international patents. Since 2009, he holds a PhD from ETH-Zurich (Switzerland), and in 2013 he received a Fulbright fellowship at the University of Princeton (USA), where he worked on innovative methodologies for accelerating engineering calculations. Dr. Chiavazzo serves as Editor of two international journals: i) Scientific Reports (Nature Springer); ii) Entropy (MDPI). He has been scientifically responsible for research projects on water purification and desalination through solar and / or thermal waste energy and has participated / participates in several European projects (FP7, H2020). He is the lecturer in charge of the undergraduate courses: "Energy Storage and Transport" (since 2014/2015) and "Advanced Engineering Thermodynamics" (since 2015/2016).

The International Conference on Innovative Applied Energy (IAPE’18)