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CLIMIT-Forskning, utvikling og demo av CO2-håndtering

Superlyophobic surfaces for efficient separation and droplet condensation of CO2

Alternative title: Superlyofobe overflater for effektiv separasjon og dråpekondensering av CO2

Awarded: NOK 9.2 mill.

Project Number:


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Project Period:

2016 - 2021

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The realisation of full-scale implementation of carbon capture and storage (CCS) in the near future is of high importance in order to limit global warming. To realise large scale CCS, we need innovative solutions that can give substantial cost reductions for CO2 capture, transport and storage. The NanoDrop project answers to this challenge by addressing equipment for condensation and separation of CO2, which is frequently applied in technologies both for capture and transport. Through the use of nanotechnology for surface manipulation we sought to increase efficiency of the CO2 condensation process. Nanostructured surfaces may increase the heat transfer which will increase the efficiency of the liquefaction and reduce the costs of the process. The results will also be applicable for a number of other applications involving condensation and liquefaction. For pre-combustion CO2 capture, a low-temperature separation process has been developed by SINTEF ER during the last decade. When using existing equipment, the process will reduce the cost of CCS by 30% compared to current commercial capture systems in cases where transport of CO2 is performed in liquid state by ship. The application of more efficient heat exchangers and separators will further decrease the costs. Through multiscale modelling and experimental activity, the NanoDrop project will qualitatively and quantitatively explore the benefits of incorporating nanotechnology in CCS process equipment, with the ultimate goal to push for full-scale deployment of CCS in Norway and the world. In 2018, a review article to identify possible materials and surfaces structures to promote dropwise condensation of water and knowledge extension to CO2 was published in "Advances in Colloid Science and Interfaces". An experimental apparatus for testing the heat transfer during CO2 condensation on various surfaces was designed and constructed. Promising micro- and nanostructured surfaces have been fabricated at the NTNU Nanolab and were characterized and tested. Key features of the test facility include a chamber pressurized with high purity CO2 (up to 20 bar), a cooling block inside the chamber to control the nanostructured surface temperature down to -55°C, and a window to allow us to visualize the condensation phenomena with a high speed camera. The camera and pressure chamber are located in a cold box and the entire laboratory area is enclosed in a moisture controlled drying room to prevent condensation and icing, with all process controls (programmed in LabView) outside the dry room. During the project surfaces of copper, aluminum, stainless steel, as well as micro- and nanostructured structures have been tested in the facility. A journal article describing the methodology and the facility, and presenting the results from the investigation of the flat surfaces is currently under review in "Experimental Thermal and Fluid Science". A journal article presenting the results on the micro- and nanostructured surfaces is under review in "International Journal of Heat and Mass Transfer". We found that the heat transfer on a micro- and nanostructured surface increase with over 60%. Advanced molecular dynamics (MD) theory to understand and predict the condensation mechanisms is essential. In 2018, one journal publications on MD results was accepted. Using molecular dynamics simulations, we have determined the contact angle and condensation behavior of CO2 droplets on a smooth solid surface. A paper was published in 2020 in Environmental Science & Technology entitled "CO2 Wetting on Pillar-Nanostructured Substrates" where large-scale MD simulations have been utilized to investigate the contact angle and wetting behaviors of CO2 droplets on pillar-structured Cu-like surfaces. The findings will in the future inform the design of CO2-phobic solid surfaces for dropwise condensation of CO2, which can increase the heat transfer even further. In 2019, a poster from the project was presented at TCCS-10, and a poster presentation will be given at the GHGT-15 in March 2021. In January 2021, the PhD thesis "Mechanisms and enhancements of CO2 condensation heat transfer" was submitted. The thesis contains the main experimental results of the project.

During the project period, one PhD and one PostDoc have submitted and completed their work. The results of the academic work are published (or under review) in international peer reviewed journals, 3 published and 2 under review. The main outcome of the project has been the development of a surface that enhance the CO2 condensation heat transfer. If implemented in process equipment, the impact will be lower energy demand of CO2 liquefaction during processing for ship transport, or as a part of the capture process. The lower energy demand is reflected in lower process costs.

The ultimate goal of the researcher project is to accelerate the process necessary for reaching full-scale CO2-capture by reducing cost and increasing energy-efficiency. The concept of NanoDrop is to combine knowledge of gas liquefaction, surface properties and nanotechnology to develop the scientific fundament for heat exchangers and separators with increased efficiency. The project aims at fabricating superlyophobic surfaces (i.e. non-wetting) for induction of dropwise condensation of CO2 on the walls of the heat exchangers and in separators, instead of filmwise condensation. The surfaces will be fabricated using methods known from nanotechnology, and will create the necessary interface tension to induce dropwise condensation. Hence, significantly increase the efficiency of the liquefaction process. The results will also be applicable for a number of other applications involving condensation.

Publications from Cristin

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CLIMIT-Forskning, utvikling og demo av CO2-håndtering