Nicolaas started working at HySA Infrastructure in March 2017 as a research engineer after completing his M.Eng in Chemical Engineering in 2016, also at HySA Infrastructure. His main area of expertise is microchannel reactor technology for ammonia decomposition as well as power-to-gas (CO2 methanation) applications. He is enrolled part-time for his PhD.
M.Eng (Chemical), North-West University, Potchefstroom, 2016
B.Eng (Chemical), North-West University, Potchefstroom, 2014
Schumacher K, Engelbrecht N, Everson RC, Friedl M, Bessarabov DG. Steady-state and transient modelling of a microchannel reactor for coupled ammonia decomposition and oxidation. International Journal of Hydrogen Energy 2019;44(13):6415-6426.
Sekoai PT, Ouma CNM, du Preez SP, Modisha P, Engelbrecht N, Bessarabov DG, Ghimire A. Application of nanoparticles in biofuels: An overview. Fuel 2019;237:380-397.
Engelbrecht N, Chiuta S, Bessarabov DG. A highly efficient autothermal microchannel reactor for ammonia decomposition: Analysis of hydrogen production in transient and steady-state regimes. Journal of Power Sources 2018;386:47–55.
Ndlovu IM, Everson RC, Chiuta S, Neomagus HWJP, Langmi HW, Ren J, Engelbrecht N, Bessarabov DG. A performance evaluation of a microchannel reactor for the production of hydrogen from formic acid for electrochemical energy applications, International Journal of Electrochemical Science 2018;13:485–97.
Engelbrecht N, Chiuta S, Everson RC, Neomagus HWJP, Bessarabov DG. Experimentation and CFD modelling of a microchannel reactor for carbon dioxide methanation, Chemical Engineering Journal 2017;313:847–57.
Chiuta S, Engelbrecht N, Human G, Bessarabov DG. Techno-economic assessment of power-to-methane and power-to-syngas business models for sustainable carbon dioxide utilization in coal-to-liquid facilities. Journal of CO2 Utilization 2016;16:399-411.
In recent years, the production of environmentally-friendly hydrogen via water electrolysis has been one of the most promising technologies to convert and potentially store renewable energy in a chemical energy carrier. However, a few elements are lacking with regards to a hydrogen economy, as large scale and far reaching hydrogen infrastructure is not yet fully established. The inadequate volumetric energy density of hydrogen is also a contributing factor to this hindrance. In this work, microchannel reactor technology will be used to evaluate two catalytic reactions for the processing of hydrogen. The first reaction is the reforming of ammonia for hydrogen production, intended for hydrogen fuel cell use in off-grid applications. Ammonia is one of the most mass produced chemicals worldwide and is a carbon-free energy carrier. The second reaction is the hydrogenation (methanation) of carbon dioxide. The production of methane from clean hydrogen offers the ability to store, at large-scale, renewable energy in natural gas networks. In both these cases, a reactor is required with load following capabilities. For hydrogen production from ammonia, the demand-side power requirement governs the rate of hydrogen produced (reactor throughput). On the other hand, the process of converting hydrogen to methane is susceptible to the availability of excess renewable energy, whether it is solar- or wind-based.
Conventional reactors such as fixed-beds are well-known, but are generally intended for continuous operation. Also, conventional reactors have heat and mass transfer properties that will limit highly exothermic/endothermic reactions under demanding reactor conditions. Microchannel reactors however are designed as multifunctional reactor/heat exchanger devices that can sustain the dynamic operation required and provide the high heat transfer characteristics necessary for effective operation. There exists a necessity to demonstrate micro-engineered reactors which could supply increased gas throughput, as compared to what was done historically. In order to do so, the microchannel reactor will be operated autothermally; in essence being able to sustain its own heat requirement, and either being balanced with an endothermic (heat consuming) reaction, or a cooling fluid. In this thesis, significant focus will be shed on the thermal and heat transfer effects within the reactor. As a result, the advantages of microchannel reactor technology will be demonstrated for the two hydrogen-based processes through experimental work as well as comparative CFD modelling.
Supervisors: Prof Raymond C. Everson, Dr Dmitri G Bessarabov