Christopher Wayne Turner

Design and control of a two-stage electro-hydraulic valve actuation system

This paper discusses the design and control of a two-stage electro-hydraulic camless Variable Valve Actuation (VVA) system designed for gasoline engines that encompass a wide rpm range. The VVA portion of each engine valve assembly in the system consists of two miniature pilot valves, a proportional valve, a compound engine valve actuator and an engine valve return mechanism. The design and proper control of these devices allow for variable valve timing, lift, duration, seating velocity and flank velocity. This flexibility enables an array of combustion strategies. Many of these strategies (such as Miller cycle operation, cylinder and valve deactivation, etc.) have been tested on fired engines that have been redesigned to incorporate the VVA system. Test results for both bench and fired engines running in a dynamometer cell are presented. These results indicate the current level of controllability of the system and the power consumed by the system in a variety of test conditions.

Scale-Up of Flat Plate Photobioreactors Considering Diffuse and Direct Light Characteristics

This study investigates the scaling of photobioreactor productivity based on the growth of Nannochloropsis salina incorporating the effects of direct and diffuse light. The scaling and optimization of photobioreactor geometry was analyzed by determining the growth response of a small‐scale system designed to represent a core sample of a large‐scale photobioreactor. The small‐scale test apparatus was operated at a variety of light intensities on a batch time scale to generate a photosynthetic irradiance (PI) growth dataset, ultimately used to inform a PI growth model. The validation of the scalability of the PI growth model to predict productivity in large‐scale systems was done by comparison with experimental growth data collected from two geometrically different large‐scale photobioreactors operated at a variety of light intensities. For direct comparison, the small‐scale and large‐scale experimental systems presented were operated similarly and in such a way to incorporate cultivation relevant time scales, light intensities, mixing, and nutrient loads. Validation of the scalability of the PI growth model enables the critical evaluation of different photobioreactor geometries and design optimization incorporating growth effects from diffuse and direct light. Discussion focuses on the application of the PI growth model to assess the effect of diffuse light growth compared to direct light growth for the evaluation of photobioreactors followed by the use of the model for photobioreactor geometry optimization on the metric of areal productivity. Biotechnol. Bioeng. 2012; 109:363–370.