Conference Session

Thermodynamics, Fluids and Heat Transfer II

Collection

2014 ASEE Annual Conference & Exposition

Authors

Amir Karimi, University of Texas, San Antonio; Randall D. Manteufel, University of Texas, San Antonio

Tagged Divisions

Mechanical Engineering

. closed systems, evaluation of properties,state principle, internal energy vs. enthalpy, transient vs. steady state, realizing entropy is athermodynamic property, reversibility, and correct application of process equations vs. rateequations. A few examples are discussed here with specific strategies to promote studentlearning.Students often struggle to distinguish between isothermal and adiabatic processes. Students findit counter-intuitive that a system can absorb energy by a heat transfer, Q without a change intemperature during a process. In many cases the temperature increases with heating, but if thesystem undergoes a phase change at constant pressure the temperature remains constant. Aclassic example is boiling water trapped in a piston

Conference Session

Thermodynamics, Fluids and Heat Transfer II

Collection

2014 ASEE Annual Conference & Exposition

Authors

Jessica W. Clark, University of Maine; John R. Thompson, University of Maine; Donald B. Mountcastle, University of Maine

Tagged Divisions

Mechanical Engineering

semester. As a reminder, the heat transfer cannotbe directly determined from a P-V diagram. This part of the task requires students to use the FirstLaw, ∆U = Q − W , and knowledge of the work and internal energy comparisons from the othersections of the task. We have also created a one-dimensional work task (see Fig. 2) appropriate for students in ourintroductory courses. In this task, students compare the net work done in propelling a cart the samedistance using two different propulsion methods. We have also altered the phrasing from a questionto a statement. This task differs in two main ways from the P-V task. First, the variables aren’tstate variables. We would need to use tension and extension to get the equivalent one-dimensionaltask and

Conference Session

Thermodynamics, Fluids, and Heat Transfer I

Collection

2014 ASEE Annual Conference & Exposition

Authors

Natasha Smith P.E., University of Southern Indiana; Brandon S. Field, University of Southern Indiana

Tagged Divisions

Mechanical Engineering

special cases.As a case in point, the Fundamentals of Engineering Supplied-Reference Handbook includes 6first law equations for closed systems and 11 for control-volume systems. This often leads toconfusion and detracts from the students’ appreciation for the fundamental nature of the principle.The authors have typically modeled problem solutions using only two first law equations: one forclosed systems and one for control volumes. The form of the first law used for control volumes isprovided below. dEcv /dt = Q˙ cv − W ˙ cv + Σm ˙ i (hi + Vi2 /2 + gzi ) − Σm ˙ e (he + Ve2 /2 + gze ) (1)The left term

Conference Session

Programming, Simulation, and Dynamic Modeling

Collection

2014 ASEE Annual Conference & Exposition

Authors

Mark David Bedillion, South Dakota School of Mines and Technology; Raymond Jon Raisanen, South Dakota School of Mines and Technology; Mohamed Hakeem Mohamed Nizar, SDSM&T Mechanical Engineering

Tagged Divisions

Mechanical Engineering

mechanicsof the solutions. These graphs are then tied to the SolidWorks simulation results as shown in Figs.2 and 4.Introducing Lagrange’s EquationsIn addition to these standard difficulties, the authors have added the challenge of teach partialderivatives by teaching the equations of motion via Lagrange’s equations.5 Lagrange’s equations,particularly for conservative mechanical systems, are relatively easy to implement for sophomoredynamics students. The equation has the form d ∂T ∂T ∂V − + = 0, (1) dt ∂ q˙j ∂qj ∂qjwhere T is the kinetic energy of the system, V is the potential

Conference Session

Capstone Courses and Project Based-Learning

Collection

2014 ASEE Annual Conference & Exposition

Authors

David R. Sawyers Jr., Ohio Northern University

Tagged Divisions

Mechanical Engineering

between the vertical section and the first horizontal section of pipe. The pumpcurve is hp = (100 - 0.01Q2), where hp is the pump head in feet, Q is the flowrate in gpm, and is a dimensionless parameter that specifies the size of pump/motor combination chosen ( canhave any value between 0 and 10). The cost of the pump/motor is $700.If the flowrate at each exit is 10 gpm, determine the pipe diameter that minimizes the totalsystem cost. Also calculate the pump inlet pressure (in psig), and the power required (in hp) ifthe pump/motor has a combined efficiency of 70%.This problem can be solved using EES, but there are several numerical issues that must beconsidered.  Since EES is an iterative solver, it may or may not converge. In addition