Sprayable, Thin & RobUst Carbon Nanofiber ComposiTe for JUmping DRopwisE ConDensation

Project Information

STRUCTURED

Grant agreement ID: 101034816

DOI

10.3030/101034816

Project closed

EC signature date 16 March 2021

Start date 1 October 2021

End date 31 March 2023

Funded under

• EXCELLENT SCIENCE - Future and Emerging Technologies (FET)

Total cost

No data

EU contribution

€ 100 000,00

Coordinated by

EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH
Switzerland

Periodic Reporting for period 1 - STRUCTURED (Sprayable, Thin & RobUst Carbon Nanofiber ComposiTe for JUmping DRopwisE ConDensation)

Reporting period: 2021-10-01 to 2023-03-31

Summary of the context and overall objectives of the project

Nearly 80% of the 23000 TWh global power generation is attained by thermal power based on closed-loop steam cycles. This includes coal and gas-fired power plants, thus making the power generation sector the largest contributor to greenhouse gas (GHG) emissions. As the world electricity demand grows, it is imperative that power generation transitions to a more ecologically sustainable developmental path. We propose that this can be achieved through a significant and sustained increase in the thermodynamic efficiency of the steam cycle. Specifically, we target a disruptive enhancement in the efficiency of steam condensers, an integral part of the steam cycle and a key component driving the thermal efficiency of the overall cycle. These condensers condense spent steam from turbines on cooled metallic surfaces in order to complete the full steam cycle. In commercial condensers, the condensed steam forms a continuous film of condensate, known as filmwise condensation (FWC) on the metallic surfaces which severely limits the overall thermodynamic efficiency of the condenser and as a result of the entire power plant. We have developed a nanocomposite material to remedy this situation which can lead to a hitherto unseen improvement in commercial condenser efficiency and consequently, unprecedented reduction in the fossil fuel consumption of the power generation sector thus saving input costs and reducing GHG emissions. We have demonstrated that this coating is able to spontaneously eject condensed droplets even smaller than 100 μm through a gravity-independent mechanism (coalescence-induced droplet jumping), thereby achieving a 9 times higher heat transfer performance as compared to conventional condensation. To go a step further, the primary three objectives of STRUCTURED consist of further development of the coating manufacturing, its scalability and implementation in industrial processes involving heterogeneous condensation, as well as establishing the foundation for product commercialization.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In terms of material development, we have identified 3 areas in that we directed our efforts toward improving the overall performance of our coating. These are: 1) optimize the spraying suspension composition and dispersion by testing different solvents and types of carbon-based nanomaterials, 2) improve the adhesion to various substrates by using surface primers, and 3) re-evaluate the condensation heat transfer of the new formulation. We indeed achieved improvement in the coating uniformity, and we enhanced the adhesion of the coating while maintaining high heat transfer performance.
After the fabrication protocol was established, we worked on how to make the process scalable. This required cost and time considerations. Since the application of our coating requires a spray-based process, appropriate considerations should be made for the coating application to industrial condensers, due to their shape. For this reason, we purchased an industrial HVLP spray gun and we demonstrated the spraying of our material through this apparatus at a larger surface compared to the prototypes that we have tested so far. We have also given a redesign of the process for fabrication based on commercial scaled-up systems. Finally, we constructed a new prototype copper tube coated with our material. Relevant to the longevity of our material, our goal was to perform additional durability tests relevant to industrial condensers. We performed a one-month test at the University College London under atmospheric conditions. The result that was most of the surface of the coating sustained dropwise condensation. However, some visual degradation was observed, but it could originate from the type of mounting that was selected to hold the sample in place.
On the business and management side, we created a website, designed a logo, and established an initial business plan. We also took several actions toward forming a spin-off company. These included discussions with the technology transfer department, attendance of workshops, preparation of a pitching deck, coaching sessions with entrepreneurs, etc. Finally, we have mitigated the risks caused by the lab closure periods during the pandemic and we believe that we have fulfilled all our goals in the original time framework.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

STRUCTURED aims to put previous research outcomes into industrial application. Our material is expected to provide significant enhancements in the performance of industrial condensers, applicable in various industrial settings such as power plants and separation facilities. As the nanocomposite coating is shown to be more durable that other state-of-the-art superhydrophobic materials, its real-world application presents strong promises towards long-term condensation heat transfer improvements. In industrial condensers and heat exchangers, surfaces are often designed very close to each other to maximize overall efficiency (in the form of packed tubes). This places significant constraints on various coating methods. In STRUCTURED we develop a scalable spray method to coat uniformly surfaces in a cylindrical shape, as in existing condensers. We expect a lasting impact in the industry in terms of coating methods, not only in condensers but also in areas where surface coating in tight spaces is favored.
Due to the enormous and growing capacity of power plants and the demand for energy, a tiny increase in efficiency translates to a significant reduction in energy consumption. In 2019, coal consumption for the electric power sector amounted to 490 million metric tons, the combustion of which generates GHG as well as air pollutants with a direct impact on human health. The possibility to increase energy production without the corresponding increase in the use of fossil fuels thus brings about a lasting impact on reducing our footprint towards adverse climate change, as well as indirect economic losses due to air pollution, notably in public health and tourism. A successful technological transfer of our developed coating from the research domain to the industry suggests a sustainable reduction in energy consumption in most condensing applications. The estimated cost of the nanocomposite coating, based on retail prices instead of lower wholesale prices, is ~ USD 45 per meter squared. The relatively low cost for its long operational timeframes before deterioration enables potential active use in industry, which in turn reduces emissions of greenhouse gases and promotes energy sustainability. We try to involve active manufacturers and users of condensers, to understand their demands and challenges to enable a productive co-design process with our knowledge in the area. Overall, STRUCTURED fills the gap of the current lack of exchange of expertise between industry and research in the area of materials for condensation heat transfer.

STRUCTURED logo