Conference Session

Thermodynamics, Fluids, and Heat Transfer I

Collection

2009 Annual Conference & Exposition

Authors

Andrew Foley, United States Coast Guard Academy; Michael Plumley, United States Coast Guard Academy

Tagged Divisions

Mechanical Engineering

S1 =Entropy out. Ta = Ambient Temperature Figure 1. Simple pipe model for second law consideration. Application of the energy accounting equation as described by Foley [3], gives : Q& 1 / W& − ( m& e ) in / ( m& e ) out − E& gen ? E& CV . (1) Which for a steady flow, no work situation simplifies to : Q&1 ? m& .C p (T1 / T2 ) . (2) This is usually as far as we need to go in most practical problems, and hence any issues of entropy do not arise. However there is much to be learned by considering the entropy

Conference Session

Thermodynamics, Fluids, and Heat Transfer II

Collection

2009 Annual Conference & Exposition

Authors

Laura L. Pauley, Pennsylvania State University

Tagged Divisions

Mechanical Engineering

tolengthen the mask and a carriage return before and after to increase the height of the mask.Example 1 also used “explicit,ALL” for several calculations. In this case, the definingequation was used as a mask for the “explicit,ALL” words. Several problems can be seen inthe hf calculation. The numerical value for V was not substituted into the equation. Instead,the previous equation defining V in terms of Q and d was inserted and the numerical valuesfor Q and d displayed. In addition, the Darcy friction value previously calculated is notrounded in the “explicit,ALL” equation. Attempts to resolve these problems were notsuccessful.Solving Equations Analytically. Equations can be solved symbolically (analytically) using[cntl .]. (The two keystrokes in

Conference Session

Mechanical Engineering Poster Session

Collection

2009 Annual Conference & Exposition

Authors

Rogelio Luck, Mississippi State University; B.K. Hodge

Tagged Divisions

Mechanical Engineering

. Page 14.65.10 gal ( Flowrate : Start the flow after 100 min ) Q( t) 2∧ if t ≅ 100min min 0 otherwise Qgen1( T) 6600∧ W if T > KfromF( 130) ∧ K ( Heater ON if the temp. is below 130F ) 0 otherwise Qgen2( T) 4400∧ W if T > KfromF( 130) ∧ K 0 otherwiseUsing an energy balance to solve for the time rate of change (Slopes) of the temperatures :  1 s   τ∧ C ∧ V1∧ τ∧ Cp∧ ∗ Tin / Ta+ ∧ Q( t∧ s

Conference Session

Thermodynamics, Fluids, and Heat Transfer I

Collection

2009 Annual Conference & Exposition

Authors

Andrew Foley, United States Coast Guard Academy; Michael Plumley, United States Coast Guard Academy

Tagged Divisions

Mechanical Engineering

? ? Cv.TE − p E .v E ? u E − p E .v E (10) mReturning now to our control volume A,DU A ? ∑ Q A / ∑ W A − m I .(u I − p I .v I ) / m E .(u E − p E .v E ) (11)Again it is interesting to note that the convected terms comprise properties that arecompletely defined outside of the control volume A which we are ultimately analyzing.At this point convention is that there is ‘convenience’ to be had by grouping the terms in thebrackets into one term. i.e. the property enthalpy (h) is justified.Hence,DU A ? ∑ Q A / ∑ W A − m I .(hI ) / m E .(hE ) (12) This convenience however comes at a price. First, internal energy is a property that wasclosely related to pressure and temperature and fundamental in our

Conference Session

Thermodynamics, Fluids, and Heat Transfer II

Collection

2009 Annual Conference & Exposition

Authors

Michael Maixner, United States Air Force Academy; James Baughn, UC Davis

Tagged Divisions

Mechanical Engineering

) Page 14.103.11 m Fin parameter, ? hP kA c (1/m) M ? hPkA c θ b (W) P Fin perimeter (m) q Heat transfer rate (W) Rt,f Fin resistance, ? θ b q f (K/W) t Fin thickness (m) T Temperature (ºC, K) x Distance along fin, measured from base (m) Greek Θ Temperature difference between fin and ambient temperature, ? T - T♣ (ºC, K) ε Fin effectiveness, ? q f hA c θ b η Fin efficiency, ? q f q max Subscripts b Base of fin c Cross-section, or corrected length f Fin L Condition at fin tip max Maximum possible ∞ Condition

Conference Session

Thermodynamics, Fluids, and Heat Transfer II

Collection

2009 Annual Conference & Exposition

Authors

Gerald Recktenwald, Portland State University; Robert Edwards, Pennsylvania State University, Erie; Douglas Howe, Portland State University; Jenna Faulkner, Portland State University; Calvin Hsieh, Portland State University

Tagged Divisions

Mechanical Engineering

, not on the details of data acquisition. The laboratory exercise begins with warm-up problems on the rate form of the first law, andon possible choices of control volumes for the system. We found these warm-up problems to bevery helpful because qualitative reasoning is a new skill for students, and because (in ourapproach) the students have only recently been reintroduced to the first law of thermodynamics.See Appendix B, section 3.3. The first part of the blender exercise investigates the effect of varying the amount of waterin the blender. Qualitative analysis involves manipulating the rate form of the First Law ofthermodynamics dT ˙ ˙ mc = Q

Conference Session

Thermodynamics, Fluids, and Heat Transfer II

Collection

2009 Annual Conference & Exposition

Authors

Amir Karimi, University of Texas, San Antonio

Tagged Divisions

Mechanical Engineering

undergraduate heat transfertextbooks is usually limited to fins of uniform cross-sectional area. For more complex finconfigurations, only efficiency charts are provided in most heat transfer textbooks1-15. Analysisfor fins of variable cross-sectional areas or annular fins results in more complex differentialequations. The solutions for temperature distribution involve complex functions such as Besselfunctions. The analyses for these types of fins are not typically fully covered in an introductoryheat transfer course. Instead the results are shown in the form of fin efficiency charts.The fin efficiency is defined as q act q act ϕf ? ? (1

Conference Session

Outstanding Contributions to Mechanical Engineering Education

Collection

2009 Annual Conference & Exposition

Authors

Sivakumar Krishnan, Indiana University-Purdue University, Indianapolis; M. Razi Nalim, Indiana University-Purdue University, Indianapolis

Tagged Divisions

Mechanical Engineering

coolingsystems? What is the purpose of finding the mass flow rate of the air in the house?”A: “Mass flow rate is used only in the calculating air exchanges between the house and theambient as it happens due to closing and opening of doors, leakage through the windows anddoors etc. and this is given as 0.4.”Q: “Shouldn't the heat input for solar radiation be higher in the summer than in the winter,considering we are closer to the sun in the summer time? Would you please elaborate on thismatter?”A: “Good question! In winter, the angle made by the sun is more oblique at the earth. (see linkfor a picture depicting this). Therefore, more of it may reach the house through the windows.However, there are other factors such as which direction the windows are

Conference Session

Thermodynamics, Fluids, and Heat Transfer I

Collection

2009 Annual Conference & Exposition

Authors

B. Terry Beck, Kansas State University; Bill Whitson, Kansas State University; Greg Payne, Kansas State University; Trevor Heitman, Kansas State University

Tagged Divisions

Mechanical Engineering

visualization is the determination of the airspeed or flow rate in the ductmodel. The airspeeds are too small for the normal wind tunnel measurement system whichmakes use of the pressure drop in the wind tunnel converging section resulting from theBernoulli effect. An indirect method is possible, by measuring the volumetric flow rate supplied Page 14.208.7to the rake manifold from the smoke generation system. If the total volumetric flow rate of aircontaining smoke is Q, then the average discharge velocity from N identical rake tubes will be U= Q/(NA), where A is the internal cross-sectional area of a single typical rake tube. Since theexit tube flow

Conference Session

Student Learning and Assessment

Collection

2009 Annual Conference & Exposition

Authors

Raghu Echempati, Kettering University; Enayat Mahajerin, Saginaw Valley State University; Anca Sala, Baker College

Tagged Divisions

Mechanical Engineering

direct assessment in the course include weekly homework (H), weeklyquizzes (Q), midterm exam (M), final exam (F), and design project (P). The studentpopulation from the 2007-08 academic year consisted of 8 students. The Table belowshows the achievement of each student in each category, as well as the class average. Table 3: Individual student performance and class average in the five assessment categoriesStudent HW Q M F P Total %1 99 93 81 98 95 466 93.22 99 94 85 90 100 468 93.63 69 90 60 77 100 396

Conference Session

Design Projects in Mechanical Engineering II

Collection

2009 Annual Conference & Exposition

Authors

Brian Novoselich, United States Military Academy; Joel Dillon, United States Military Academy

Tagged Divisions

Mechanical Engineering

Page 14.1285.6of multiple teams for 2008:Q: How did having multiple Baja teams this year help or hurt your success? 1. It helped inspire an internal competition. 2. It helped by creating internal competition. It hurt by dividing people and assets. 3. Helped- competition kept us driven and let us see other alternatives to problems. Hurt- split up the members that really wanted to work on the vehicle and not choosing members hurt team dynamics. 4. Helped- teams were able to show the other difficulties and problems that would be applicable to both. Required increased insight to produce two separate products. 5. I think it helped because we fed ideas off one another, but a consolidated team with those that worked

Conference Session

Thermodynamics, Fluids, and Heat Transfer II

Collection

2009 Annual Conference & Exposition

Authors

Subrata Bhattacharjee, San Diego State University; Christopher Paolini, San Diego State University

Tagged Divisions

Mechanical Engineering

ignited. To analyze the resulting process, launch the premixed closed-process IGcombustion daemon located in the Daemons> Systems> UnsteadyProcess> Specific>Combustion> Premixed> IG Model page. Configure the reaction in the Reaction Panel fortheoretical combustion of octane. Evaluate the reactants state with p1 = 1 atm, T1 = 298 K, andpartially evaluate the products state with Vol2 = Vol1 (for a constant-volume process). In theProcess Panel, load state-1 as the beginning state (b-state) and state-2 as the final state (f-state),and enter Q = W = 0. Click Calculateand then Super-Calculate to obtain thefinal state. The final pressure andtemperature are found in state-2 as1065 kPa and 2911 K, respectively. Inprocesses where a