A simulation model capable of performing the calculations involved in defining a crude preheat train

A simulation model has been developed for a system of ex changers to preheat the feed to a crude distillation unit. In conjunction, a Fortran program for the performance of the model calculations by digital computer was written. Two types of preheat system were simulated, a single train system and a split (or parallel) train system. A number of features were included in the program for flexibility and versatility. A particular effort was made to have the model represent as economical a preheat system as possible. The model program was used to obtain computer-calculated results for both single-train and split-train preheat systems. Computer runs were made to show the effect of using different temperature approach values. The computer output data as printed for several sample problems is presented. Results have been analyzed with regard both to type of preheat system and to temperature approach value

Gear Tooth Mesh Stiffness: A Comparison of Calculation Approaches

This work compares spur gear tooth mesh stiffness calculations using two approaches. The first is a common approach from the literature that calculates the mesh stiffness by dividing the mesh force by the mesh deflection, which we call the average slope method. The second approach calculates the local slope of the force-deflection curve about a nominal deflection. The two approaches result in meaningfully different mesh stiffness predictions that persist for wide ranges of applied torque and for gear teeth with tooth surface modifications. It is shown that each calculation approach has its own distinct use, broadly divided as average slope mesh stiffness for static analyses and local slope for dynamic analyses. Furthermore, the two stiffness calculation approaches lead to different vibration models. This means for vibration analyses the choice is not solely which of the two stiffnesses to use but also how to implement that stiffness appropriately in a model. Even though the mesh stiffnesses in this work are calculated using a finite element/contact mechanics approach, the findings are equally valid for mesh stiffnesses obtained from conventional finite element methods, analytical models, and experiments

Characterizing meteorological forecast impact on microgrid optimization performance and design

A microgrid consists of electrical generation sources, energy storage assets, loads, and the ability to function independently, or connect and share power with other electrical grids. Thefocus of this work is on the behavior of a microgrid, with both diesel generator and photovoltaic resources, whose heating or cooling loads are influenced by local meteorological conditions. Themicrogrid\u27s fuel consumption and energy storage requirement were then examined as a function of the atmospheric conditions used by its energy management strategy (EMS). A fuel-optimal EMS, able to exploit meteorological forecasts, was developed and evaluated using a hybrid microgrid simulation. Weather forecast update periods ranged from 15 min to 24 h. Four representative meteorological sky classifications (clear, partly cloudy, overcast, or monsoon) were considered. Forall four sky classifications, fuel consumption and energy storage requirements increased linearly with the increasing weather forecast interval. Larger forecast intervals lead to degraded weather forecasts, requiring more frequent charging/discharging of the energy storage, increasing both the fuel consumption and energy storage design requirements. The significant contributions of this work include the optimal EMS and an approach for quantifying the meteorological forecast effects on fuel consumption and energy storage requirements on microgrid performance. The findings of this study indicate that the forecast interval used by the EMS affected both fuel consumption and energy storage requirements, and that the sensitivity of these effects depended on the 24-hour sky conditions

Service-Learning in One State: Results of the North Carolina Service-Learning Inventory

Recent years have seen greatly expanded interest in service-learning among educators at both the K-12 and college levels. By most accounts, the initiation of service-learning programs and courses has come about in response to a recognized need to provide more effective citizenship education and to do a better job of preparing young people to be active members of their communities (see, for example, Barber). What is less clear, however, is the overall shape and substance of these programs. Because service-learning usually has a strong local component, not very much is known of the broader patterns and trends at the national and state levels

Plausible responses to the threat of rapid sea-level rise for the Thames Estuary

This paper considers the perceptions and responses of selected stakeholders to a scenarion of rapid rise in sea-level due to the collapse of the West Antarctic ice sheet, which could produce a global rise in sea-level of 5 to 6 metres. Through a process of dialogue involving one-to one interviews and a one-day policy exercise, we addressed influences on decision-making when information is uncertain and our ability to plan, prepare for and implement effective ways of coping with this extreme scenario. Through these interactions we hoped to uncover plausible responses to the scenario and identify potential weaknesses in our current flood management approaches to dealing with such an occurrence. By undertaking this exploratory exercise we hoped to find out whether this was a feasible way to deal with such a low probability but high consequence scenario. It was the process of finding a solution that interested us rather than the technical merits of one solution over another. We were not intending to produce definitive set of recommendations on how to respond but to gain insights into the process of making a decision, specifically what influences it and what assumptions are made.Sea level rise, London

Performance of an Evaporative Cooling System in a Gestation House

This field study was conducted to determine the effectiveness of an evaporative pad cooler for modifying the environment in a gestation house in Kentucky and to compare the measured results with the calculated performance of evaporative cooling systems. The building used in the study was a 68-crate gestation house, as described in Figure 1. The building was oriented east-west and was well insulated. There were no windows in the facility. It was fully occupied, throughout the study, with sows with an average weight of 350 lbs. A negative pressure system was used to ventilate the building with a 36 single-speed exhaust fan located in the east end wall (Figure 1). A 4\u27 x 12\u27 evaporative pad was located in the west end wall adjacent to the air intake. Shutters were mounted on the outside of the building to provide shade for the pads and to protect them during inclement weather