Employing Computer Optimization in Powerplant Design

As an undergraduate senior elective course, powerplant design is not commonly offered in most mechanical engineering curricula. Many aspects of poweplant design may be included in an advanced undergraduate thermodynamics course. Traditionally, assigned exercises involving powerplants have involved laborious interpolation from thermodynamic tables in order to obtain steam and condensate properties. With the advent of computerized thermodynamic functions, more advanced exercises can be formulated, with the time-intensive aspect of table interpolation no longer necessary. This paper presents a portfolio of exercises which have been incorporated into a powerplant design course involving plant efficiency optimization through the use of pressure and temperature design selections at various strategic points in the plant. Additionally, components such as cooling towers involving psychrometric calculations are handled using computerized property software and incorporated into the powerplant design course. The models for these problems are generated from scratch by the students with no special software beyond the commonly-used thermodynamic property packages that are available as part of Engineering Equation Solver (EES), Microsoft Excel, MATLAB or Mathcad. Using these tools, students can be exposed to the effects of powerplant component design features, such as re-heater pressure and feedwater heater pressure on overall plant performance. Additionally, students can explore the effects of outdoor relative humidity on the performance of cooling towers for various design parameters they might select. Generating plots from the results of their designs gives students insight into the sensitivity of the performance of various components to the design parameters they have been asked to vary. They can also observe the effects of the performance of individual components on the overall performance of the plant. By assembling components over the duration of the semester, the interrelationship of the segments of the plant can be seen. For example, an integrated plant exercise includes the effect of outdoor relative humidity on overall plant performance, taking into account the interrelation between outdoor humidity, cooling water temperature, condenser vacuum and turbine output. Fundamental computer-based exercises related to nuclear power generation are also included, allowing students to observe the influence of moderator atomic mass on the thermalization rate of neutrons, and the time-response of reactor thermal power to primary coolant loop sizing. Each of these exercises is generated by employing foundational principles using the generic software packages mentioned previously.