Karne de Boer

Development and validation of a two phase CFD model for tubular biodiesel reactors

The use of biodiesel as an alternative to diesel has gained increasing momentum over the past 15 years. To meet this growing demand there is a need to optimise the transesterification reactor at the heart of the biodiesel production system. Assessing the performance of innovative reactors is difficult due to the liquid–liquid reaction mixture that is affected by mass transfer, reaction kinetics and component solubility. This paper presents a Computational Fluid Dynamic model of a tubular reactor developed in ANSYS CFX that can be used to predict the onset of mixing via turbulent flow. In developing the model an analysis of the reaction mixture is provided before the presentation of experimental data, which includes flow visualisation results and temperature dependant viscosity and density data for each phase. The detailed data and model development procedure represents an advancement in the modelling of the two phase transesterification reaction used in biodiesel production.

Economic and Energy Analysis of Large-Scale Microalgae Production for Biofuels

Microalgae biofuels have been under development for the last 40 years; however, in the last 6 years, this development has intensified due to higher oil prices and wider acceptance of anthropogenic climate change. Despite the excellent potential of algal biofuels, they are not yet commercially viable. The reason for this lack of progress is examined in this chapter by firstly reviewing the range of different technology options for biofuels from microalgae. Secondly, an analysis of the available techno-economic and energy assessments is performed highlighting the effect that each system element has on the overall viability.

Past, present and future of microalgae cultivation developments

Microalgae cultivation is a promising methodology for solving some of the future problems of biomass production (i.e. renewable food, feed and bioenergy production). There is no doubt that in conjunction with conventional growth systems, novel technologies must be developed in order to produce the large-scale sustainable microalgae products. Here, we review some of the most promising existing microalgae biomass growth technologies and summarise some of the novel methodologies for sustainable microalgae production.

Development of a model for identifying the optimal biogas system design in Sub-Saharan Africa

Biogas technology has been recognised as a suitable technology for improving energy access, waste management, and sanitation in Sub-Saharan Africa (SSA). Uptake of the technology in the region has been sporadic and currently dissemination programmes are limited to five countries. The main barriers hindering larger dissemination include high installation costs, inadequate user training, insufficient servicing, and inappropriate designs. Poor design choices, mainly due to overlooking the user energy needs and local conditions, contribute to the short lifespan of many installed biogas systems. This research aims to address the gap in appropriate designs of biogas systems through the development of a model that identifies optimal designs for particular applications in SSA based on user defined priorities of sustainability criteria. TOPSIS, a multi-criteria decision making method is used in the model to identify the optimal system based on the priority rating of the criteria and the designs that are feasible according to the main parameters. The model was applied to a typical Kenyan household where a 9 m3 modified CAMARTEC solid state digester was identified as the optimal biogas system.