ITSE Things You Should Know
Contents
1. For thermodynamics applications you will find T especially helpful for retrieving thermodynamic property data while solving a problem that requires one numerical solution or for varying parameters to investigate their effects For heat transfer applications you will find HT especially helpful for solving problems associated with these topics transient conduction using the lumped capacitance method and one term series analytical solutions estimating convection coefficients using correlations requiring thermophysical properties of fluids as a function of temperature and blackbody radiation functions Things You Should Know Version1 05 31 02 Page 1 of 7 Getting Started with T and IHT When you first start up T and IHT you will be asked whether you want to run the Tutorial If you are new to the software you should go through the Tutorial so that you can build these basic skills e enter equations from the keyboard e solve equation sets with an understanding of Initial Guesses and solver behavior e perform Explore and Graph operations and e understand general features of the solver Intrinsic Functions For T the Tutorial is self contained and provides you with all that you need to learn the basic features of the software After working through the tutorial you will be able to solve basic thermodynamic problems vary parameters and make graphs Your skills with T will serve you as well with HT since their architecture solver2. of the capabilities of T IT capabilities tied to topics beyond the scope of ITSE e Exergy analysis e Reacting mixtures and combustion e Chemical and phase equilibrium IT Examples Fundamentals and ITSE equivalence guide Fundamentals ITSE Description 2 1 3 1 Evaluating expansion work 3 3 4 3 Stirring water at constant volume 3 5 4 5 Plotting thermodynamic data using software 4 5 5 5 Calculating compressor power 6 14 7 12 CD ROM Evaluating the isentropic compressor efficiency 8 5 8 4 Regenerative cycle with open feedwater heater 9 6 9 4 Brayton cycle with irreversibilities 9 14 12 8 CD ROM Effect of back pressure converging nozzle 12 14 10 4 Spray steam humidifier 13 8 Not included Determining the adiabatic flame temperature 14 6 Not included Determining the equilibrium flame temperature 14 7 Not included Determining the equilibrium flame temperature using software Things You Should Know Version1 05 31 02 Page 3 of 7 IHT Some Special Tips IHT was designed to accompany the text Fundamentals of Heat and Mass Transfer 4ed 2002 and Introduction to Heat Transfer 5ed Wiley 2002 and includes a number of features that will enhance your study of heat transfer However many other features are beyond the scope of coverage in TSE so it is not useful to track any equivalence between the two texts with respect to topics and examples for use of the software It is the p
3. Things You Should Know About Interactive Thermodynamics IT and Interactive Heat Transfer IHT What is the software all about IT and IHT provided on your CD ROM are Windows based general purpose nonlinear equation solvers with built in functions for solving thermodynamics and heat transfer problems The packages were designed for use with the texts Fundamentals of Engineering Thermodynamics Moran amp Shapiro 4 Ed 2000 Wiley and Introduction to Heat Transfer Incropera amp DeWitt 4 Ed 2002 Wiley respectively The equation numbering text section topic identification and content are specific to those texts However the software is also well suited for use with Introduction to Thermal Systems Engineering ITSE t is our purpose here to identify features of IT and IHT that will help you make good use of the software in solving thermodynamics and heat transfer problems Why use T and IHT You should consider T and HT as productivity tools to reduce the tediousness of calculations and as learning tools to permit building models and exploring influences of system parameters Use the software as you would a hand calculator to check solutions Solve systems of equations that otherwise would require iterative hand calculations Sweep across the value of a parameter to generate a graph But best of all use the special features of the packages identified below that will greatly facilitate your problem solving assignments
4. ence will return more accurate results than the one term solutions of the text The Sphere T_xt T_xt_trans Sphere rstar Fo Bi Ti Tinf Eq 16 112 QoverQo Q_over_Qo_trans Sphere Fo Bi Eq 16 114 Sphere with an initial uniform temperature Ti subjected to sudden convection conditions Tinf h as represented in Fig 16 26 These functions represent the multiple term series analytical solution and hence will return more accurate results than the one term solutions of the text These functions are used to solve the sphere transient conduction problem of Example 16 11 Things You Should Know Version1 05 31 02 Page 6 of 7 IHT Codes for ITSE Text Examples Six examples from TSE have been solved using IHT The examples were chosen to illustrate the use of the functions described in the previous sections The following table identifies the features illustrated in the example and the identity of the HT file that is located in the directory on your CD ROM labeled IHT Text Example Codes You can open one of these files while in IHT press the Solve button and examine the results in the Data Browser Text Example Content File name 16 9 Workpiece temperature time history during heat treatment E16 _09 msm Use of the derivative function DER T t for solving the transient energy balance including radiation exchange as treated in Comment 4 16 10 Plane wall experiencing sudden convective conditions E16_10A msm Use of transient co
5. engine and other key features are similar For IHT the Tutorial while labeled as Example 1 6 is based on ITSE Example 15 3 Curing a Coating with a Radiant Source Step by step instructions will lead you through the construction of the model solution for the unknown variables and graphical representation of a parametric study You should become familiar with the Help Index which serves as the User s Manual for the software You should read the first section IHT Environment so that you understand the structure of the software Later we ll introduce you to some special Intrinsic Functions To find out more about using the software you should go to the sections that follow entitled IT Some Special Tips or IHT Some Special Tips Things You Should Know Version1 05 31 02 Page 2 of 7 IT Some Special Tips IT was designed to accompany the text Fundamentals of Engineering Thermodynamics Fundamentals and it includes a number of features that enhance your study of thermodynamics Some of the features however are tied to topics that are beyond the scope of Introduction to Thermal Systems Engineering ITSE Also IT has a folder with a large number of examples from Fundamentals Most of these examples are in TSE as well and the table below shows the correspondence Some of the T examples are not relevant to the thermal systems text as noted in the table The entire selection of examples though provides a complete set of illustrations
6. es from your CD ROM to another drive on your computer Things You Should Know Version1 05 31 02 Page 7 of 7
7. nd the LMTD heat exchanger method The strategy for dealing with stiff equations sets involves making good initial guesses and specifying upper and lower bounds Also consider developing models of more complex systems by building on simplified models For more advice see the IHT Help Solution Strategies and Hints Things You Should Know Version1 05 31 02 Page 4 of 7 Using Functions that Provide Unique Computational Capability There are four heat transfer specific intrinsic functions that provide unique computation capability for the problems of ITSE A function is a subroutine that performs a calculation based upon values of the argument provided by the user Descriptions of the function and IHT Help references follow See the final section IHT Codes for Text Examples for the identity of the IHT files that illustrate use of these functions Function Description DER T t Used to solve differential equations in this case the derivative of temperature T with respect to time t Useful for solving the transient energy balance of the for the lumped capacitance method Eq 16 81 See Example 16 9 Comment 4 HT Help reference Solver Intrinsic Functions DER Function Properties Provides functions for the thermophysical properties of selected materials liquids and gases Click on the Properties button on the Tool Bar for the substance of choice highlight window contents and drag the functions into the Workspace Properties are ba
8. nduction functions T_xt_trans Plane Wall E16 _10B msm and Q_over_Qo_trans Plane Wall The files A and B correspond to solutions for parts a d and Comment 2 respectively 16 11 Quenching a spherical workpiece in an oil bath E16 11 msm Use of transient conduction functions T_xt_trans Cylinder and Q_over_Qo_trans Cylinder to calculate quench time 17 11 Turbulent flow Steam heated water supply line E17_10 msm Use of Tfluid_avg and Properties functions with an internal flow convection correlation to determine outlet temperature for constant temperature surface condition 17 12 Free convection Cooling an electronic equipment enclosure E17_12 msm Use of Tfluid_avg and Properties functions with a free convection correlation to estimate heat flux by convection and radiation 18 4 Total emissivity from the spectral emissivity distribution E18 04 msm Use of the blackbody band emission function F_lambda_T lambda T to evaluate total emissivity as a function of temperature These files are located in the directory IHT Text Example Codes on your CD ROM When opened from HT the files appear with the msm extension IHT searches for files based on this extension but the saved session includes three other files with the same name up to eight characters but different extensions dsk eqd and eqs Remember to include all four files if you perform a copy and paste sequence to relocate the fil
9. presents the functions that will allow you to calculate the temperature distribution T x t or T r t and energy transfer relation Q Qo for the plane wall and radial system geometries The functions are keyed to equations in your text You must provide appropriate equations for the function arguments xstar x L or rstar r ro Bi Fo and Qo The initial internal energy Qo follows from Eq 16 108 See the final section IHT Codes for Text Examples for the identity of the HT files that illustrate use of these functions The Plane Wall T_xt T_xt_trans Plane Wall xstar Fo Bi Ti Tinf Eq 16 104 QoverQo Q_over_Qo_trans Plane Wall Fo Bi Eq 16 110 Plane wall with an initial uniform temperature Ti subjected to sudden convection conditions Tinf h as represented in Fig 16 25 These functions represent the multiple term series analytical solution and hence will return more accurate results than the one term solutions of the text These functions are used to solve the plane wall transient conduction problem of Example 16 10 See the next section for the identity of the HT file The Infinite Cylinder T_xt T_xt_trans Cylinder rstar Fo Bi Ti Tinf Eq 16 111 QoverQo Q_over_Qo_trans Cylinder Fo Bi Eq 16 113 Infinite cylinder with an initial uniform temperature Ti subjected to sudden convection conditions Tinf h as represented in Fig 16 26 These functions represent the multiple term series analytical solution and h
10. sed on values from TSE Appendices HT 1 to 5 For example the function for the thermal conductivity of air at one atmosphere is k k_T Air T Thermal conductivity W m K Note the temperature T must be specified in kelvin units HT Help reference Tools Properties Tfluid_avg x y Calculates the film temperature or average mean temperature for internal flow written as Tf Tfluid_avg Ts Tinf or Tmbar Tfluid_avg Tmi Tmo This function is preferred to Tf Ts Tinf 2 when working with stiff equation sets IHT Help reference Solver Intrinsic Functions Tfluid_avg Function F_lambda_T lambda T Calculates the blackbody band emission factor according to Eq 18 10a and Table 18 2 This function is especially useful for calculating total or band properties from their spectral distributions See Example 18 4 Comment 2 for an illustration of its use IHT reference Tools Radiation Exchange Radiation Functions see also from the tool bar menu Tools Radiation Band Emission Factor Things You Should Know Version1 05 31 02 Page 5 of 7 Transient Conduction with Spatial Effects IHT models have been developed for solving the transient conduction problem for a Plane Wall with Convection Sec 16 5 2 and Radial Systems Sec 16 5 3 Evaluating the one term series analytical solution for these geometries is tedious work requiring use of tables for the coefficients C and or Bessel functions The following table
11. urpose of this section to identify specific features of IHT that will increase your productivity in problem solving In addition to having basic solver literacy and good skills in using T as earlier described you will find the following topics useful in solving the heat transfer problems of ITSE Entering Equations from Text Reference Tables and Figures It has been our practice in the ITSE heat transfer chapters to summarize key concepts and equations in table or figures to facilitate convenient reference during your problem solving sessions You should be able to enter the relevant equations into the IHT Workspace and affect solutions Table Figure Content T 15 5 Rate equations for conduction convection radiation T 16 3 One dimensional conduction HE solutions resistances T 16 4 Fin equations distribution heat rates F 16 27 Semi infinite media temperature distribution heat rate T 17 3 Correlations external flow T 17 5 Correlations internal flow also with Eq 17 56 T 17 6 Correlations free convection Understanding How to Handle Stiff Equation Sets The solver engine affects solutions to the equation set comprising your model by using initial guesses to converge on the values for the unknown variables With highly non linear equations the engine might not converge within the required limits for the allowed iterations Examples of such equations include the convection correlations property functions the radiation rate equation a
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