Fundamentals Of Engineering Heat And Mass Transfer_R. C. Sachdeva.pdf

Scilab Textbook Companion for Fundamentals Of Engineering Heat And Mass Transfer by R. C. Sachdeva1 Created by Nittala Venkata Krishna B.TECH Mechanical Engineering Sastra University College Teacher Dr. Anjan Kumar Dash Cross-Checked by Lavitha Pereira May 23, 2016

1

Funded by a grant from the National Mission on Education through ICT, http://spoken-tutorial.org/NMEICT-Intro. This Textbook Companion and Scilab codes written in it can be downloaded from the ”Textbook Companion Project” section at the website http://scilab.in

Book Description Title:  Fundamentals Of Engineering Heat And Mass Transfer Author:  R. C. Sachdeva Publisher:  New Age Science Ltd., New Delhi Edition: 4 Year:   2009 ISBN:   9781906574123

1

Book Description Title:  Fundamentals Of Engineering Heat And Mass Transfer Author:  R. C. Sachdeva Publisher:  New Age Science Ltd., New Delhi Edition: 4 Year:   2009 ISBN:   9781906574123

1

Scilab numbering policy used in this document and the relation to the above book. Exa  Example (Solved example) Eqn  Equation (Particular equation of the above book) AP  Appendix to Example(Scilab Code that is an Appednix to a particular

Example of the above book) For example, Exa 3.51 means solved example 3.51 of this book. Sec 2.3 means a scilab code whose theory is explained in Section 2.3 of the book.

2

Contents Listt of Scilab Codes Lis

4

1 Ba Basi sic c Co Conc ncept eptss

5

3 OneD OneDime imensi nsiona onall Steady State State Heat Conduct Conduction ion

11

5 Tran ransie sient nt Heat Heat Conduc Conductio tion n

46

6 Fundame undamenta ntals ls of convec convectiv tive e heat transfer transfer

72

7 Forc orced ed Conve Convecti ction on Systems Systems

77

8 Nat Natural ural Con Conve vecti ction on

106

9 The Therma rmall radiati radiation on basic basic relati relations ons

123

10 Radiative Heat exchange between surfaces

131

11 Boiling and Condensation

153

12 Heat Exchangers

164

13 Diffusion Mass Transfer

187

14 Convective Mass Transfer

197

3

List of Scilab Codes Exa 1.1 Exa 1.2 Exa 1.3 Exa 1.5 Exa 1.6 Exa 1.7 Exa 3.1 Exa 3.2 Exa 3.3 Exa 3.4 Exa 3.5 Exa 3.6 Exa 3.8 Exa 3.9 Exa 3.10 Exa 3.11 Exa 3.12 Exa 3.13 Exa 3.14 Exa 3.15 Exa 3.16 Exa 3.17 Exa 3.18 Exa 3.19 Exa 3.20 Exa 3.21 Exa 3.22

Rate of heat transfer . . . . . . . . . . . . . . . . . . . Rate of heat transfer . . . . . . . . . . . . . . . . . . . Rate of radiant heat   . . . . . . . . . . . . . . . . . . . Overall heat transfer coefficient   . . . . . . . . . . . . . Heat loss per unit length . . . . . . . . . . . . . . . . Surface temperature   . . . . . . . . . . . . . . . . . . . Rate of heat loss and interior temperature . . . . . . . Tempertaure and heat flow . . . . . . . . . . . . . . . Heat flow and teperature . . . . . . . . . . . . . . . . Heat loss per square meter surface area . . . . . . . . Rate of heat flow   . . . . . . . . . . . . . . . . . . . . . Heat loss per unit length . . . . . . . . . . . . . . . . Thickness of insulation . . . . . . . . . . . . . . . . . . Rate of heat leaking   . . . . . . . . . . . . . . . . . . . Heat transfer through the composite wall . . . . . . . Surface temperature and convective conductance   . . . Heat loss and thickness of insulation   . . . . . . . . . . Heat loss from the pipe . . . . . . . . . . . . . . . . . Heat loss per meter length of pipe . . . . . . . . . . . Change in heat loss . . . . . . . . . . . . . . . . . . . Mass of steam condensed . . . . . . . . . . . . . . . . Rate of heat flow   . . . . . . . . . . . . . . . . . . . . . Heat loss and surface temperature . . . . . . . . . . . Effect of insulation on the current carrying conductor Surface temperature and maximum temperature in the wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . Surface temperature   . . . . . . . . . . . . . . . . . . . Heat transfer coefficient and maximum temperature . 4

5 6 6 7 8 9 11 12 13 14 15 15 16 17 18 19 21 22 23 24 25 26 27 28 30 31 32

Exa 3.23 3.23 Exa 3.2 3.244 Exa 3.25 3.25 Exa 3.2 3.266 Exa 3.2 3.277 Exa 3.28 3.28 Exa 3.29 3.29 Exaa 3.3 Ex 3.311 Exa 3.3 3.322 Exa 3.3 3.333 Exaa 3.3 Ex 3.344 Exa 3.35 3.35 Exaa 5. Ex 5.11 Exaa 5. Ex 5.22 Exaa 5. Ex 5.33 Exaa 5.4 Ex 5.4 Exaa 5. Ex 5.55 Exaa 5. Ex 5.66 Exaa 5. Ex 5.88 Exaa 5. Ex 5.99 Exa 5.1 5.100 Exa 5.1 5.111 Exa 5.12 Exa 5.1 5.133 Exa 5.1 5.144 Exa 5.1 5.155 Exa 5.1 5.166 Exa 5.1 5.177 Exa 5.1 5.188 Exaa 5. Ex 5.19 19 Exa 5.2 5.200 Exa 5.21 5.21 Exaa 5.22 Ex 5.22 Exa 5.2 5.233 Exa 5.24 Exaa 6. Ex 6.22 Exa 6.6 Exaa 6.7 Ex 6.7

Diameter Diamet er of wire wire and and rate rate of curr curren entt flow flow . . . . Tempe emperat rature ure dro drop p . . . . . . . . . . . . . . . . . Tempe emperat rature ure at at the cen centre tre of of orange orange   . . . . . . . Tota otall heat heat dis dissip sipate ated d. . . . . . . . . . . . . . . . Therma The rmall con conduc ductiv tivit ity y . . . . . . . . . . . . . . . Temperat emperature ure distri distributio bution n and rate of heat heat flow flow   . Ratee of heat Rat heat trans transfer fer and and temper temperatu ature re   . . . . . . Rate Ra te of he heat at flo flow w  . . . . . . . . . . . . . . . . . . Efficien Effic iency cy of the pla plate te . . . . . . . . . . . . . . . Heatt tran Hea transfe sferr coeffic coefficien ientt   . . . . . . . . . . . . . . Insu In sula lati tion on of fin . . . . . . . . . . . . . . . . . . Measur Me asureme ement nt erro errorr in temper temperatu ature re   . . . . . . . . Heat He at tr tran ansf sfer er an and d te tempe mpera ratu ture re . . . . . . . . . . Tim imee ta tak ken . . . . . . . . . . . . . . . . . . . . Tim imee ta tak ken   . . . . . . . . . . . . . . . . . . . . . Time Ti me re requ quir ired ed to coo cooll al alum umin iniu ium m . . . . . . . . . Heat He at tr tran ansf sfer er coe coeffic fficie ien nt   . . . . . . . . . . . . . . Time Ti me co cons nsta tant nt an and d ti time me per period iod   . . . . . . . . . . Tem emper perat atur uree an and d to tota tall he heat at   . . . . . . . . . . . . Time Ti me ta tak ken to co cool ol   . . . . . . . . . . . . . . . . . Tempe emperat rature ure . . . . . . . . . . . . . . . . . . . . Timee requ Tim require ired d and and dep depth th . . . . . . . . . . . . . Temperat emperature ure and total ther thermal mal ener energy gy   . . . . . . Tempe emperat rature ure . . . . . . . . . . . . . . . . . . . . Timee requ Tim require ired d for for cool cooling ing . . . . . . . . . . . . . Tempe emperat rature ure . . . . . . . . . . . . . . . . . . . . Centre Cen trelin linee tem tempera peratur turee . . . . . . . . . . . . . . Tempe emperat rature ure . . . . . . . . . . . . . . . . . . . . Surfac Sur facee tem tempera peratur turee   . . . . . . . . . . . . . . . . Time Ti me el elap apse sed d . . . . . . . . . . . . . . . . . . . . Tempe emperat rature ure . . . . . . . . . . . . . . . . . . . . Amplit Amp litude ude of of temper temperatu ature re and and time time lag . . . . . Time Ti me lag an and d heat heat flo flow . . . . . . . . . . . . . . Depth Dep th of pene penetra tratio tion n. . . . . . . . . . . . . . . . Instantaneo Instan taneous us heat remo remov val rate . . . . . . . . . Typ ypee of flo flow w . . . . . . . . . . . . . . . . . . . . Maxim Max imum um tem tempera peratur turee ris risee and hea heatt flux . . . . Type of flo flow w an and d ent entry ry le leng ngth th . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33 34 35 35 36 37 38 39 41 42 43 44 46 47 48 50 51 52 52 54 55 55 56 58 59 60 61 62 64 65 66 67 68 69 70 72 73 74

Exa 6. Exa 6.88 Exaa 6. Ex 6.99 Exaa 7. Ex 7.11 Exa 7. Exa 7.22 Exa 7.3 Exaa 7. Ex 7.44 Exaa 7. Ex 7.55 Exa 7.6 Exa 7.7 Exa 7.8 Exa 7.9 Exa 7.10 7.10 Exa 7.1 7.111 Exa 7.12 7.12 Exa 7.1 7.133 Exa 7.14 Exa 7.1 7.155 Exa 7.16 7.16 Exa 7.17 7.17 Exa 7.18 7.18 Exaa 5. Ex 5.19 19 Exa 7.2 7.200 Exa 7.21 7.21 Exa 7.2 7.222 Exa 7.2 7.233 Exaa 7. Ex 7.24 24 Exa 7.2 7.255 Exa 7.2 7.266 Exaa 8. Ex 8.11 Exaa 8. Ex 8.22 Exa 8.3 Exaa 8. Ex 8.44 Exaa 8. Ex 8.55 Exaa 8. Ex 8.66 Exaa 8. Ex 8.77 Exaa 8. Ex 8.88 Exaa 8. Ex 8.99

Head lo Head loss ss an and d po pow wer re requ quir ired ed   . . . . . . . . . . . . . . Pres Pr essu sure re dr drop op . . . . . . . . . . . . . . . . . . . . . . . Thic Th ickn knes esss of hydrod hydrodyn ynam amic ic bounda boundary ry layer layer and skin friction coefficient . . . . . . . . . . . . . . . . . . . . Local Loc al he heat at tr tran ansf sfer er coe coeffic fficie ient nt   . . . . . . . . . . . . . . Bounda Bou ndary ry la laye yerr thic thickne kness ss and and tot total al drag drag for force ce . . . . . Rate Ra te of he heat at to be re remo mov ved   . . . . . . . . . . . . . . . Drag Dr ag for orcce . . . . . . . . . . . . . . . . . . . . . . . . Thickness Thic kness of boundary lay layer er and heat trans transfer fer coeffici coefficient ent Fric rictio tion n coeffici coefficien entt and and heat heat tran transfe sferr coeffici coefficien entt   . . . . Heat loss . . . . . . . . . . . . . . . . . . . . . . . . . Heatt tran Hea transfe sferr rate rate and perc percen entag tagee of of powe powerr lost lost . . . . Heat transf transfer er coefficien coefficientt and curren currentt intensi intensity ty   . . . . . Ratee of hea Rat heatt tra transf nsfer er . . . . . . . . . . . . . . . . . . . Heatt transfe Hea transferr coefficien coefficientt and press pressure ure drop drop . . . . . . . Conve Con vect ction ion coeffi coefficie cient nt . . . . . . . . . . . . . . . . . . Convec Con vectiv tivee heat heat transf transfer er coeffici coefficient ent   . . . . . . . . . . . Avera Av erage ge tempe temperat rature ure of the the fluid fluid   . . . . . . . . . . . . Length Len gth and and heat heat trans transfer fer coeffi coefficie cient nt . . . . . . . . . . Heatt transfe Hea transferr coefficien coefficientt and heat heat transfe transferr rate . . . . Heatt transfe Hea transferr coefficien coefficientt and lengt length h of the tube tube   . . . . Nuss Nu ssel eltt nu num mber . . . . . . . . . . . . . . . . . . . . . . Heatt tran Hea transfe sferr coeffic coefficien ientt   . . . . . . . . . . . . . . . . . Heatt transfe Hea transferr coefficien coefficientt and heat heat transfe transferr rate . . . . Heatt tran Hea transfe sferr coeffic coefficien ientt   . . . . . . . . . . . . . . . . . Heatt tran Hea transfe sferr coeffic coefficien ientt   . . . . . . . . . . . . . . . . . Heat He at le leak akag agee . . . . . . . . . . . . . . . . . . . . . . . Heatt tran Hea transfe sferr coeffic coefficien ientt   . . . . . . . . . . . . . . . . . Minim Min imum um len length gth of the tube . . . . . . . . . . . . . . Boun Bo unda dary ry la lay yer th thic ickn knes esss . . . . . . . . . . . . . . . . Heat He at tr tran ansf sfer er coe coeffic fficie ien nt   . . . . . . . . . . . . . . . . . Heatt trans Hea transfe ferr coeffici coefficien entt and and rate rate of heat heat tra transf nsfer er   . . . Con Co nvec ecti tive ve he heat at lo loss ss   . . . . . . . . . . . . . . . . . . . Rate Ra te of he heat at in inpu putt   . . . . . . . . . . . . . . . . . . . . Heat He at ga gain ined ed by th thee du duct ct   . . . . . . . . . . . . . . . . . Coeffic Coe fficie ien nt of he heat at tr tran ansf sfer er . . . . . . . . . . . . . . . Rate Ra te of he heat at lo loss ss   . . . . . . . . . . . . . . . . . . . . . Rate Ra te of he heat at lo loss ss   . . . . . . . . . . . . . . . . . . . . . 6

75 76 77 78 79 80 81 83 84 85 86 87 88 89 91 92 93 94 95 95 96 98 99 10 0 10 1 10 2 10 3 10 4 10 6 10 7 10 8 10 9 11 0 11 1 11 3 11 4 11 5

Exa 8.10 8.10 Exa 8.1 8.111 Exaa 8.1 Ex 8.122 Exa 8.13 8.13 Exa 8.14 Exa 8.15 Exaa 8. Ex 8.16 16 Exaa 9. Ex 9.11 Exa 9.2 Exa 9.3 Exa 9.4 Exa 9.5 Exaa 9. Ex 9.66 Exaa 9.7 Ex 9.7 Exaa 9.8 Ex 9.8 Exa 10. 10.11 Exa 10. 10.44 Exaa 10 Ex 10.5 .5 Exa 10. 10.88 Exa 10.14 Exa 10.15 10.15 Exa 10.16 10.16 Exa 10.17 10.17 Exa 10.1 10.188 Exa 10.19 10.19 Exa 10.20 10.20 Exa 10.2 10.211 Exa 10.22 10.22 Exa 10.23 Exa 10.24 10.24 Exa 10.25 10.25 Exa 10.26 10.26 Exa 10.27 10.27 Exa 10.28 10.28 Exa 10.29 Exa 10.30 10.30 Exa 10.31

Coefficient of heat Coefficient heat transfe transferr and curre current nt inte intensit nsity y . . . Ratee of con Rat conve vecti ctive ve hea heatt loss loss   . . . . . . . . . . . . . . . Rate Ra te of he heat at lo loss ss   . . . . . . . . . . . . . . . . . . . . . Therma The rmall conduc conductiv tivit ity y and heat heat flo flow w . . . . . . . . . . Free con convec vection tion heat trans transfer fer . . . . . . . . . . . . . . Convec Con vectiv tivee heat heat transf transfer er coeffici coefficient ent   . . . . . . . . . . . Heat He at tr tran ansf sfer er   . . . . . . . . . . . . . . . . . . . . . . . Rate Ra te of so sola larr ra radi diat ation ion   . . . . . . . . . . . . . . . . . . Frac ractio tion n of ther thermal mal radi radiati ation on emmi emmitte tted d by the sur surafc afcee Hemisp Hem ispher herica icall tra transm nsmitt ittivi ivity ty . . . . . . . . . . . . . . Surfac Sur facee tem tempera peratur turee and emm emmisi isive ve pow power er . . . . . . . Emmiss Emm issivi ivity ty and wa wave ve len length gth   . . . . . . . . . . . . . . Tru ruee te tempe mpera ratu ture re of th thee body . . . . . . . . . . . . . . Rate Ra te of ab abso sorb rbpt ptio ion n and and em emmi miss ssion ion . . . . . . . . . . . Ener En ergy gy ab abso sorbe rbed d and and tr tran ansm smit itte ted d. . . . . . . . . . . . Surfac Sur facee tem tempera peratur turee   . . . . . . . . . . . . . . . . . . . Net exc exchan hange ge of ene energy rgy . . . . . . . . . . . . . . . . . Shape Sh ape fa fact ctor or . . . . . . . . . . . . . . . . . . . . . . . Net hea heatt exc exchan hange ge   . . . . . . . . . . . . . . . . . . . . Net heat exchange exchange and equilibrium equilibrium temperatur temperaturee . . . . Radiantt heat excha Radian exchange nge . . . . . . . . . . . . . . . . . . Radiantt heat excha Radian exchange nge . . . . . . . . . . . . . . . . . . Reduct Red uction ion in heat heat loss   . . . . . . . . . . . . . . . . . . Losss of heat Los heat . . . . . . . . . . . . . . . . . . . . . . . . Radiation Radiat ion heat heat transfer transfer . . . . . . . . . . . . . . . . . Net radiant radiant heat heat exchange exchange . . . . . . . . . . . . . . . . Losss of heat Los heat . . . . . . . . . . . . . . . . . . . . . . . . Net heat heat transf transfer er   . . . . . . . . . . . . . . . . . . . . . Percen Per centage tage reduction reduction in heat transfer transfer and temper temperature ature of the shield . . . . . . . . . . . . . . . . . . . . . . . Number Num ber of screen screenss . . . . . . . . . . . . . . . . . . . . Losss of heat and reduct Los reduction ion in heat . . . . . . . . . . . Error in temperatur temperaturee . . . . . . . . . . . . . . . . . . . Ratee of heat Rat heat loss   . . . . . . . . . . . . . . . . . . . . . Heat transfe transferr coefficient coefficient   . . . . . . . . . . . . . . . . . Extinction Extin ction coefficien coefficientt for radiation radiation . . . . . . . . . . . Emmissivit Emmiss ivity y of the mixture mixture   . . . . . . . . . . . . . . . Net radiation radiation exchange exchange and coefficient coefficient of heat transfer transfer 7

11 6 11 7 11 8 11 8 11 9 12 0 12 1 12 3 124 12 5 12 5 12 6 12 7 12 8 12 9 13 1 13 2 13 3 13 3 13 4 13 5 13 6 13 7 13 8 13 9 14 0 14 1 14 2 14 3 14 4 14 5 14 6 14 7 14 8 14 9 15 0 151

Exa 11. 11.11 Exaa 11. Ex 11.22 Exa 11.3 11.3 Exa 11. 11.44 Exaa 11 Ex 11.5 .5 Exa 11. 11.66 Exa 11.7 11.7 Exa 11. 11.88 Exa 11. 11.99 Exa 11.10 11.10 Exa 12.1 12.1 Exa 12.2 12.2 Exa 12. 12.33 Exa 12. 12.44 Exa 12. 12.55 Exa 12.6 12.6 Exa 12.7 Exa 12. 12.88 Exa 12. 12.99 Exa 12.10 12.10 Exa 12.11 12.11 Exa 12.12 12.12 Exa 12.13 Exa 12.14 Exa 12.15 12.15 Exa 12.16 12.16 Exa 12.17 12.17 Exa 12.18 Exa 13. 13.11 Exa 13.2 13.2 Exaa 13 Ex 13.3 .3 Exa 13. 13.44 Exa 13. 13.55 Exaa 13. Ex 13.66 Exaa 13 Ex 13.7 .7 Exa 13. 13.88 Exaa 13 Ex 13.9 .9 Exa 14.1

Tempe emperat rature ure of the the surf surface ace . . . . . . . . . . . . . . . Burn Bu rnou outt he heat at flu flux x . . . . . . . . . . . . . . . . . . . . Heat trans transfer fer coeffici coefficient ent and powe powerr dissipati dissipation on . . . . Heatt tran Hea transfe sferr coeffic coefficien ientt   . . . . . . . . . . . . . . . . . Heat He at tr tran ansf sfer er   . . . . . . . . . . . . . . . . . . . . . . . Thick Thi cknes nesss of con conden densat satee film film . . . . . . . . . . . . . . Ratee of heat Rat heat transfe transferr and conden condensat satee mass flow flow rate rate   . Heatt tra Hea transf nsfer er rat ratee . . . . . . . . . . . . . . . . . . . . Ratee of for Rat format mation ion of cond condens ensate ate . . . . . . . . . . . . Condensati Conde nsation on rate rate . . . . . . . . . . . . . . . . . . . . Overa Ov erall ll heat heat trans transfer fer coeffi coefficie cient nt   . . . . . . . . . . . . . Overa Ov erall ll heat heat trans transfer fer coeffi coefficie cient nt   . . . . . . . . . . . . . Heatt ex Hea exch chang anger er are areaa   . . . . . . . . . . . . . . . . . . . Heatt ex Hea exch chang anger er are areaa   . . . . . . . . . . . . . . . . . . . Length Len gth of hea heatt exc exchan hanger ger . . . . . . . . . . . . . . . . Surfac Sur facee area and and rate of cond condens ensati ation on of steam steam   . . . . Effectiv Effec tivee log log mean mean temper temperature ature diffe differenc rencee . . . . . . . Areaa of Are of heat heat exc exchan hanger ger . . . . . . . . . . . . . . . . . Areaa of Are of heat heat exc exchan hanger ger . . . . . . . . . . . . . . . . . Surfac Sur facee area area . . . . . . . . . . . . . . . . . . . . . . . Number Num ber of tube passes passes and number number of tubes per pass . Surface Surfa ce area area and temperature temperature   . . . . . . . . . . . . . . Total heat transfer transfer and surface temperatur temperaturee   . . . . . . Paramete Par ameters rs of heat exchanger exchanger   . . . . . . . . . . . . . . Exit temper temperature ature . . . . . . . . . . . . . . . . . . . . . Outlett temperatur Outle temperaturee . . . . . . . . . . . . . . . . . . . Outlett temperatur Outle temperaturee . . . . . . . . . . . . . . . . . . . Diameter Diame ter and length length of heat exchange exchangerr . . . . . . . . . Avera Av erage ge mole molecul cular ar weig weight ht   . . . . . . . . . . . . . . . . Masss and molar Mas molar ave averag ragee veloci velocitie tiess and flux flux . . . . . . Diffu Di ffusi sion on flu flux x  . . . . . . . . . . . . . . . . . . . . . . . Initia Ini tiall rate rate of lea leak kage . . . . . . . . . . . . . . . . . . Losss of ox Los oxyge ygen n by by diffu diffusio sion n . . . . . . . . . . . . . . . Mass Ma ss tr tran ansf sfer er ra rate te . . . . . . . . . . . . . . . . . . . . Diffu Di ffusi sion on ra rate te . . . . . . . . . . . . . . . . . . . . . . Diffusi Diff usion on coeffi coefficie cient nt . . . . . . . . . . . . . . . . . . . Time Ti me re requ quir ired ed . . . . . . . . . . . . . . . . . . . . . . Convec Con vection tion mass trans transfer fer coefficie coefficient nt . . . . . . . . . . 8

15 3 15 4 15 5 15 6 15 7 15 8 15 9 16 0 16 1 16 2 16 4 16 5 16 6 16 7 16 9 17 0 17 1 17 2 17 3 17 4 17 6 17 7 17 9 18 0 18 2 18 3 18 4 18 5 18 7 18 8 18 9 19 0 19 1 19 2 19 3 19 4 19 5 19 7

Exa 14.2 Exa 14.3 Exa 14.4 Exa 14.5 Exa 14.6 Exa 14.7 Exa 14.8 Exa 14.9 Exa 14.10 Exa 14.11

Local Mass transfer coefficient . . Mass Transfer coefficient . . . . . . Mass transfer coefficient   . . . . . . Average mass transfer coefficient   . Mass transfer coefficient   . . . . . . Steady state temperature . . . . . True air temperature . . . . . . . . Relative humidity . . . . . . . . . Specific humidity . . . . . . . . . . Rate of evaporation . . . . . . . .

9

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

198 199 200 201 201 202 203 204 205 206

Chapter 1 Basic Concepts

Scilab code Exa 1.1  Rate of heat transfer

1   / / C h a p t e r −1 , Exa mpl e 1 . 1 , Pa ge 9 2 //

================================================================= 3 4 5 6 7 8

clc   clear

//INPUT DATA   L = 0 . 0 2 ; // T h ic ne s s o f s t a i n l e s s s t e e l p l a t e i n m   T = [ 5 5 0 , 5 0 ] ; // T em pe ra tu re s a t b ot h t he f a c e s i n degree C 9   k = 1 9 . 1 ; // Thermal C on d u ct iv it y o f s t a i n l e s s s t e e l a t 3 0 0 d e g r e e C i n W/m .K 10 11   //CALC9ULATIONS 12   q = ( ( k * ( T ( 1 ) - T ( 2 ) ) ) / ( L * 1 0 0 0 ) ) ; // H eat t r a n s f e r e d

p er

u n i a r e a i n kW/mˆ 2 13 14   //OUTPUT 15   mprintf ( ’ The h ea t t r a n s f e r e d t hr ou gh t he m a t e r i a l p e r u n i t a r e a i s %3 . 1 f kW/mˆ 2 ’ ,q )

10

16 17 //=================================END OF PROGRAM

==============================

Scilab code Exa 1.2  Rate of heat transfer

1   / / C h a p t e r −1 , Exa mpl e 1 . 2 , Pa ge 1 1 2 //

================================================================= 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

clc   clear

         

//INPUT DATA L = 1 ; // L en g th o f t h e f l a t p l a t e i n m w = 0 . 5 ; // Width o f t he f l a t p l a t e i n m T = 3 0 ; // A i r s tr ea m t em p er a tu re i n d e g re e C h = 3 0 ; / / C o n v e c t i v e h e a t t r a n s f e r c o e f f i c i e n t i n W/m ˆ2.K T s = 3 0 0 ; // T em pe ra tu re o f t he p l a t e i n d e gr e e C

  //CALCULATIONS   A = ( L * w ) ; // Area o f t he p l a t e i n mˆ2   Q = ( h * A * ( T s - T ) / ( 1 0 0 0 ) ) ; // H eat t r a n s f e r i n kW   //OUTPUT   mprintf ( ’ H eat t r a n s f e r

r a t e i s %3 . 2 f kW ’ ,Q )

//=================================END OF PROGRAM ==============================

Scilab code Exa 1.3  Rate of radiant heat

11

1   / / C h a p t e r −1 , Exa mpl e 1 . 3 , Pa ge 1 1 2 //

================================================================= 3 4 5 6 7 8 9 10

clc   clear

//INPUT DATA   T = 5 5 ; // S u r f a ce t em p er at u re i n d e g re e C   //CALCULATIONS   q = ( 5 . 6 6 9 7 * 1 0 ^ - 8 * ( 2 7 3 + T ) ^ 4 ) / 1 0 0 0 ; // The r a t e a t wh ic h

t h e r a d i a t o r e mi ts r a di a n t h ea t p er u n i t a re a i f   i t b e ha v es a s a b l a c k body i n kW/mˆ 2 11 12   //OUTPUT 13   mprintf ( ’ The r a t e a t wh ich t he r a d i a t o r e mi ts

r a d i a n t h e at p e r u n i t a r e a i s %3 . 2 f kW/mˆ 2 ’ ,q ) 14 15 //=================================END OF PROGRAM

==============================

Scilab code Exa 1.5  Overall heat transfer coefficient

1   / / C h a p t e r −1 , Exa mpl e 1 . 5 , Pa ge 2 0 2 //

================================================================= 3 4 5 6 7 8 9

clc   clear

//INPUT DATA   k = 0 . 1 4 5 ; / / Therma l c o n d u c t i v i t y o f F i r e b r i c k i n W/m. K   e=0.85; / / E m i s s i v i t y   L = 0 . 1 4 5 ; // T hi ck ne ss o f t he w a ll i n m 12

10 11 12 13 14 15 16 17

         

T g = 8 0 0 ; // Gas t e m pe r a tu r e i n d e g r e e C T w g = 7 9 8 ; // Wall t em pe ra tu re i o n g as s i d e i n d e g r ee C h g = 4 0 ; / / F il m c o n d u ct a n c e on g a s s i d e i n W/mˆ 2 . K h c = 1 0 ; / / Fi lm c o nd u ct a nc e on c o o l a n t s i d e i n W/mˆ 2 .K F = 1 ; // R a d i at i o n Sh ap e f a c t o r b et we en w a l l and g a s

  //CALCULATIONS

  R 1 = ( ( ( e * 5 . 6 7 * 1 0 ^ - 8 * F * ( ( T g + 2 7 3 ) ^ 4 - ( T w g + 2 7 3 ) ^ 4 ) ) / ( T gT w g ) ) + ( 1 / h g ) ) ; // Thermal r e s i s t a n c e i n v e r s e 18   R 2 = ( L / k ) ; // T herm al r e s i s t a n c e 19   R 3 = ( 1 / h c ) ; / / Th erma l r e s i s t a n c e 20   U = 1 / ( ( 1 / R 1 ) + R 2 + R 3 ) ; // O v er a l l h ea t t r a n s f e r

c o e f f i c i e n t i n W/mˆ 2 .K 21 22   //OUTPUT 23   mprintf (  ’ O v e r a l l h e a t t r a n s f e r W/mˆ2.K’ ,U )

coefficient

i s %3 . 3 f  

Scilab code Exa 1.6  Heat loss per unit length

1   / / C h a p t e r −1 , Exa mpl e 1 . 6 , Pa ge 2 1 2 //

================================================================= 3 4 5 6 7 8 9 10 11

clc   clear

         

//INPUT DATA D = 0 . 0 5 ; // O ut si de d i am et er o f t he p i pe i n m e=0.8; // Emmissi vity T = 3 0 ; / /Room T e mp e ra t ur e i n d e g r e e C T s = 2 5 0 ; // S u r f a ce t em p er at u re i n d e gr e e C h = 1 0 ; / / C o n v e c t i v e h e a t t r a n s f e r c o e f f i c i e n t i n W/m ˆ2.K

12

13

13   //CALCULATIONS 14   q = ( ( h * 3 . 1 4 * D * ( T s - T ) ) + ( e * 3 . 1 4 * D * 5 . 6 7 * 1 0 ^ - 8 * ( ( T s + 4 7 3) ^ 4 - ( T + 2 7 3 ) ^ 4 ) ) ) ; // Heat l o s s p er u n i t l e n g t h o f  

p i p e i n W/m 15 16   //OUTPUT 17   mprintf ( ’ H eat l o s s p er u n i t l e n g t h o f p ip e i s %3 . 1 f   W/m ’ ,q ) 18 19 //=================================END OF PROGRAM

==============================

Scilab code Exa 1.7   Surface temperature

1   / / C h a p t e r −1 , Exa mpl e 1 . 7 , Pa ge 2 1 2 //

================================================================= 3 4 5 6 7 8 9 10 11 12 13 14 15

clc   clear

           

//INPUT DATA A = 0 . 1 ; // S u r f ac e a r ea o f w at er h e a t er i n mˆ2 Q = 1 0 0 0 ; // Heat t r a n s f e r r a t e i n W T w a t e r = 4 0 ; // T em pe ra tu re o f w at er i n d e g re e C h 1 = 3 0 0 ; / / H e a t t r a n s f e r c o e f f i c i e n t i n W/m ˆ 2 . K T a i r = 4 0 ; // T em per at ure o f a i r i n d e gr e e C h 2 = 9 ; / / H e a t t r a n s f e r c o e f f i c i e n t i n W/m ˆ 2 . K

  //CALCULATIONS   T s w = ( Q / ( h 1 * A ) ) + T w a t e r ; / / T e m pe r at u re when u s e d i n

w at er i n d e g r ee C 16   T s a = ( Q / ( h 2 * A ) ) + T a i r ; / / T em pe ra tu re when u s ed i n

i n d eg re e C 17

14

ai r