No abstract

Kinetics of the autoxidation of a Jet-A fuel (POSF-2827) were examined with a near-isothermal flowing test rig (NIFTR) using passivated heat-exchanger tubing over the range 438-478 K. Analysis of the O 2 dependence for autoxidation of fuel having an initial O 2 saturation of 2.5-100% resulted in a reaction order of 0.5. Analysis for air-saturated fuel data based on the expected chain mechanism for a half-order O 2 dependence and second-order termination yielded log(k ap / M -1/2 s -1 ) ) (12.9 ( 0.4) -(36.9 ( 0.8)/θ, where k ap is the apparent rate constant and θ ) 2.303RT kcal mol -1 (R is the ideal gas law constant, and T is absolute temperature). Inferences from the derived kinetic parameters suggest that initiation involves H-atom abstraction from either a vinyl or an aromatic fuel species.

A common barrier to achieving design intent is the absence of comprehensive information about operational performance during design development. This results in uninformed decision-making which impacts on actual building performance, in particular Whole Life Costs (WLC). It is proposed that Building Information Modelling (BIM) has the potential to facilitate a more comprehensive and accurate design approach from the initial stages if the model can utilize reliable and robust cost and performance data from buildings in use. This paper describes the initial findings of a research project that has investigated the integration of WLC estimation into BIM processes. The study focusses specifically on the rapidly emerging Private Rental Sector (PRS) as the build-to-rent market has repeatable tasks and similar workflow patterns, roles and responsibilities, but impacts of WLC can significantly influence the business model. The study adopted a mixed method approach for the development and validation of a structured standardized process for timely WLC estimation through BIM. The research identified a number of barriers. These included varying definitions of WLC calculation methodologies; the availability and standards of data sources, in particular, the misalignment of coding systems for identification and classification of components at various levels of development, proprietary ownership of data, lack of knowledge and skills in team members to produce and/or utilize data sources, and limitations of software. However, the research proposes that these may be addressed by a reverse-engineered systematic process that uses the Integrated DEFinition (IDEF) 3 structured diagramming modelling technique that can be incorporated into a software model and has developed a model for a systematic approach for BIM-enabled WLC assessment based on CE principles which would include access to live data streams from completed buildings. The paper describes this model development which has the potential to enhance BIM lifecycle management through an augmented decision-making approach that is integral to the natural design development process.

No abstract

Surface fouling in aircraft fuel lines that results from autoxidation of aviation fuel remains a serious and very complicated problem. This area has been studied using two Jet-A fuels, POSF-2827 and POSF-2980. The results of a series of dynamic experiments conducted in a single-pass, tubular heat exchanger operated at very slow flow rates under near-isothermal conditions are reported herein. Such studies, by minimizing complications resulting from fluid dynamics and heat flow, constitute a simpler global approach to the chemistry of fouling. The basis for the selection of experimental test conditions is discussed, and data from measurements of dissolved oxygen and surface deposition as a function of fuel stress duration are presented. The effects of parameters such as reaction temperature, tube diameter, experimental test time, and fuel dopants are considered.