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In this study, the influence of three operational parameters (agitation rate, gas flowrate and gas hold up) and their interactions on the overall volumetric mass transfer coefficient (k La) of carbon dioxide (CO2) for microalgae cultivation in stirred tank bioreactors were investigated using Response Surface Methodology (RSM). The three variables were modelled with overall mass transfer coefficient as the response using historical data design in the Design Expert 6.0.8. The response of the model developed was in line with data used for model development from the R² values of the developed model. The study revealed that the historical data RSM design is an efficient statistical technique for providing appropriate empirical model for relating the operational parameters and predicting the optimum operating conditions affecting the kLa of CO2 which is the major determinant of the amount of the same gas consumed by microalgae to achieve maximum growth in bioreactors. [ABSTRACT FROM AUTHOR]

This study investigated the influence of three operational parameters (liquid viscosity, pipe diameter and sand concentration) and their interactions on sand minimum transport condition (MTC) in multiphase pipelines using response surface methodology (RSM). Historical data: liquid viscosity (A) at 1, 7, 20, 105, 200, 340 cP; pipe diameter (B) at 0.0776 and 0.10 m; sand concentration (C) at 50 and 200 lb of sand per 1000 bbl of fluid, were correlated with the response (MTC). A two-factor interaction (2FI) regression model was developed and validated prior to optimization studies. The effects of the combination of these factors were also ascertained with 3D plots. The result showed that the predicted data had a reasonable agreement with the experimental data with the values of R2 (0.9941) and Adj-R2 (0.9869). The predicted optimum conditions of the operating parameters were observed at liquid viscosity (335.63 cP), pipe diameter (0.08 m) and sand concentration (115.61 lb/bbl) to achieve minimum sand MTC of 0.130242 m/s which were coherent with the experimental optimum conditions 340 cP liquid viscosity, 0.08 m pipe diameter, 125 lb/1000bbl sand concentrations and 0.130242 m/s MTC. Liquid viscosity and pipe diameter were the most significant operating parameters from the 3D plots. The study revealed that the response surface methodology (RSM) is an efficient statistical technique for providing appropriate empirical model for relating the operational parameters, and predicting the optimum operating conditions affecting sand MTC, a veritable parameter in evaluating sand transport in pipeline multiphase flow. [ABSTRACT FROM AUTHOR]

Carbon capture and storage (CCS) has been established as a viable technology for the mitigation of climate change caused mainly by anthropogenic greenhouse gas emissions into the atmosphere. Ever since the publication of the special report on CCS by the Intergovernmental Panel on Climate Change in 2005, there has been an increased research and development in all areas of CCS. Some of these research involves use of numerical methods and models for optimizing storage and ensuring effective long term containment. In this paper, we propose a workflow for building and calibrating 3D preinjection and 4D geomechanics modelling to assess caprock and fault integrity for geologic carbon dioxide storage. The workflow presented here describes a seamless end-to-end process which combines a transparent flow of data with an easy-to-use graphical user interface. The workflow can conduct 3D static and 4D flow-, pressure-, and temperature-coupled calculations for rock deformations, failure and stresses. In highly heterogeneous and complex models, the workflow is capable of modelling multiple hundred faults, and multiple thousand discrete fractures. It allows the geological model, despite its high degree of complexity to be maintained throughout the geomechanical analyses process. [ABSTRACT FROM AUTHOR]