Interdisciplinary Teaching in the Field of Resilient Energy Systems: Experiences with Expert Lecture Series Combined with Workshops

The increased complexity of renewable energy systems derives in uncertain and vulnerable systems behavior, making necessary for energy experts to understand and apply resilience studies with interdisciplinary approaches. With this aim, we have designed a postgraduate course on resilience of energy systems, pursuing an “exchange interdisciplinarity” level that enables students to (i) become aware of competing approaches in terms of methods and theories stemming from different disciplines, and (ii) to critically argue on the suitability of presented concepts for energy systems design and management. The course aimed at achieving a sound level of exchange interdisciplinarity as defined in relevant literature. We chose the following specific teaching methods and didactic items to facilitate this aim and address the different challenges of interdisciplinary education identified from the literature: fundamental introduction (FI), expert interviews and deepening workshops. The FI aimed at providing a sound common basis for understanding the perspectives and approaches from different disciplines. The expert lecture series exposed students to the broadness of state-of-the-art approaches existing in resilience research for energy systems, while the deepening workshops allowed students to develop a deep and critical appraisal of the disciplinary approaches and their relations. The course impact is evaluated through the standard questionnaire for teaching evaluation from the University of Oldenburg. The evaluation shows that the course fostered a critical and interdisciplinary thinking, with a high and interactive participation through the use of multiple didactic measures. This is supported by the high satisfaction of the students, the high level of engagement and academic performance and the qualitative perception from the lecturers. Topics of similar complexity or interdisciplinarity in energy higher education, such as sustainability, technology assessment or energy systems analysis could also benefit from such a course design

Bio-based nanofluids of extraordinary stability and enhanced thermal conductivity as sustainable green heat transfer media

Nanofluids (NFs) as a new generation of heat transfer media can be applied inter alia as engine coolants, in the microelectronic industry for the cooling of electronic components and systems, and in solar panels. In the present study, the extraordinarily, that is, more than 1 year, stable NFs composed of multi-walled carbon nanotubes (MWCNTs), biomass-derived 1,2- propanediol or 1,3-propanediol, and poly(N-vinylpyrrolidone) were created and studied. The thermal conductivity and density of NFs did not change over 8 months, and NFs did not sediment over 14 months. The real image of NFs determined using transmission electron cryo-microscopy allowed us to prove that the extraordinary stability and enhanced thermal conductivity were resulted by fully individualized MWCNTs in the continuous phase and MWCNTs stabilized in dispersions by shorter carbon nanoparticles and mostly homogenous poly(N-vinylpyrrolidone) coating. The maximum enhancement in thermal conductivity was 22 and 20% for NFs composed of 2 wt % MWCNTs in comparison with that of pure 1,2-propanediol and 1,3-propanediol, respectively. The improved thermal properties were accompanied by the practically Newtonian nature of all NFs. The cytotoxicity test on normal human dermal fibroblasts indicated that the use of diols diminished the toxicity of MWCNTs. Finally, the thermal conductivity and Prandtl number of bio-based NFsas compared with those of commercial heat transfer fluids DOWCAL 200 and DOWCAL Npredestine them as superb green heat transfer media in sustainable energy systems

Thermophysical properties of IoNanofluids composed of 1-ethyl-3- methylimidazolium thiocyanate and carboxyl-functionalized long multi-walled carbon nanotubes

The concept of IoNanofluids (INFs) as the stable dispersions of nanoparticles in ionic liquids was proposed in 2009 by Nieto de Castro’s group. INFs characterize exciting properties such as improved thermal conductivity, non-volatility, and non-flammability. This work is a continuation of our studies on the morphology and physicochemistry of carbon-based nanomaterials a ecting thermal conductivity, viscosity, and density of INFs. We focus on the characterization of dispersions composed of long carboxylic group-functionalized multi-walled carbon nanotubes and 1-ethyl-3-methylimidazolium thiocyanate. The thermal conductivity of INFs was measured using KD2 Pro Thermal Properties Analyzer (Decagon Devices Inc., Pullman, WA, USA). The viscosity was investigated using rotary viscometer LV DV-II+Pro (Brookfield Engineering, Middleboro, MA, USA). The density of INFs was measured using a vibrating tube densimeter Anton Paar DMA 5000 (Graz, Austria). The maximum thermal conductivity enhancement of 22% was observed for INF composed of 1 wt% long carboxylic group-functionalized multi-walled carbon nanotubes

Thermophysical properties of nanofluids composed of ethylene glycol and long multi-walled carbon nanotubes

In this work, thermal conductivity, viscosity, isobaric heat capacity, and density of stable carbon-based nanofluids are presented. The nanofluids under study are composed of 1,2-ethanediol (ethylene glycol, EG) and long multi-walled carbon nanotubes (MWCNTs), so-called ‘in-house 16h’ (synthesized in our laboratory via catalytic chemical vapor deposition during 16 h with a diameter of 60–80 nm and length of 770 m). Poly(N-vinylpyrrolidone) (PVP) was used to increase the stability of nanofluids. The nanofluids were prepared via an ultrasonication-assisted, three-step method while their key thermophysical characteristics were obtained using the hot-wire technique and rotary viscometer. As a result, the addition of MWCNTs significantly improved the thermal conductivity of nanofluids by 31.5% for the highest 1.0 wt% (0.498 vol%) long MWCNT content, leaving the Newtonian character of the nanofluids practically intact

Bio-Based Nanofluids of Extraordinary Stability and Enhanced Thermal Conductivity as Sustainable Green Heat Transfer Media

Nanofluids (NFs) as a new generation of heat transfer media can be applied inter alia as engine coolants, in the microelectronic industry for the cooling of electronic components and systems, and in solar panels. In the present study, the extraordinarily, that is, more than 1 year, stable NFs composed of multi-walled carbon nanotubes (MWCNTs), biomass-derived 1,2- propanediol or 1,3-propanediol, and poly(N-vinylpyrrolidone) were created and studied. The thermal conductivity and density of NFs did not change over 8 months, and NFs did not sediment over 14 months. The real image of NFs determined using transmission electron cryo-microscopy allowed us to prove that the extraordinary stability and enhanced thermal conductivity were resulted by fully individualized MWCNTs in the continuous phase and MWCNTs stabilized in dispersions by shorter carbon nanoparticles and mostly homogenous poly(N-vinylpyrrolidone) coating. The maximum enhancement in thermal conductivity was 22 and 20% for NFs composed of 2 wt % MWCNTs in comparison with that of pure 1,2-propanediol and 1,3-propanediol, respectively. The improved thermal properties were accompanied by the practically Newtonian nature of all NFs. The cytotoxicity test on normal human dermal fibroblasts indicated that the use of diols diminished the toxicity of MWCNTs. Finally, the thermal conductivity and Prandtl number of bio-based NFsas compared with those of commercial heat transfer fluids DOWCAL 200 and DOWCAL Npredestine them as superb green heat transfer media in sustainable energy systems