Prediction of batch heat transfer coefficients for pseudoplastic fluids ...
Prediction of batch heat transfer coefficients for pseudoplastic fluids ... Prediction of batch heat transfer coefficients for pseudoplastic fluids ...
0 beeemes negligible fu~d agaim Newt~nianbehaviGr is ~redieted. ~e equation als~ preaiets a saear-th~ing phenomenon at intermea.iate shear rates (120). Thus this equatien is very gGod if a very wide shear-rate range must be aeeurately pertrayed er if existing data must be extra~olated. There are a few disadvantages to using the Pewell Eyring equation. 1. 'Three eORstants must be evaluated. 2. The equation eannet be selved explicitly fer shear rate. 3.. The eorrelations whieh have been aeveloped using this equatien ean only be solved using published graphs. These are based en two or three parameters in addition to ~e dimensionless groups represented by the eeordinates (42, 43) • The Ostwald-deWaele model, mere eommonly ealled the "p0wer lawlf is ancempirieal equa.tion whieh aceurately €l.eseribes the ~lew eurve of most pseudeplastie fluids ~ the shear rate range most commonly eneountered in industrial processes. (2-4 K is named the It~lu.id e0r:lsisteney i:ID.dex" and. is somewhat a.:m.alogous to the Newt@l!'lian viseesi ty in that it
va:ry withl. the slaear I'Rte.. 11.1. is ealled the n.rlw belilaTi(:!)J!' index" amd is a measure o.f the deTiatioE. from NewtoRiam belaavier. n is equal to the slo~e of the logaritkmie flow /I eurYe (Figure 2-l-e).. For Newtonian fluias E. equals 'UJ.'i\l.i ty aad the .fluid cONsistency index equals the Newt0ni~ Tis €esity. FOF pseuaeplastie .fluids n is bet"Y-lee1a zero and u-'l1li ty.. TJae ])0Wer law als® deseribes the .flow eurves of shear-taickening .fluids (dilat~t fluids), iN which case 11.1. is greater th~ unit~. Because of the aceuraey ~d simplicity of the power law, it is the most widely used rheological equation for pseudoplastie tluids. The eelasisteney index (]l0Wer law, K) is very slmilar to Newtonian viscosity in that there is ru~ appreCiable decrease for am increase in temperature amd an appreciable imerease for an increase iR concentration. For suspensions, the ratio o.f K to the viscosity o.f the suspending medium is often nearly c@E.stant. The decrease with inereasing temperature is ofte~ at the same rate as tke s@lvent or suspending medi~ (118). Tae flow wehavior index, n, is relatively constant with temperature, although there are slight changes. For water dispersible p@lymers, n :i.Jt'l.ereases slightly with tem.perature and approaches ~ity at high temperatures. As the concentration of solids or polymer imcreases, R decreases (118, 128). An~ther temperattlPe effect is that of initial ske~r stress
- Page 1 and 2: Copyright Warning & Restrictions Th
- Page 3 and 4: PREDICTION OF BATCH HEAT TRANSFER C
- Page 5 and 6: while the latter has five to seven
- Page 7 and 8: ACKNOWLEDGEMENTS The auther ex~ress
- Page 9 and 10: Chapter 1: Chapter 2: Introducticm
- Page 11 and 12: LIST OF FIGURES page 2-1 FlGW Behav
- Page 13 and 14: CHAPTER I INTRODUCTION BATCH HEAT T
- Page 15 and 16: 3 as pseudoplasticso Pseudoplastic
- Page 17 and 18: 5 ~n addition to studying the effec
- Page 19 and 20: 7 A B SLOPE = /'n- .( 10 ~y FIG 2-1
- Page 21: 15.5, 183, 185).. Most of their eff
- Page 25 and 26: 13 RHEOLOGIC_~ INVESTIGATION OFPO~~
- Page 27 and 28: IS In(s) (2-8 (2-9 where Re is the
- Page 29 and 30: '7 ft~ easier method of calibrating
- Page 31 and 32: 19 of' thixotropic breakdown l'Ji t
- Page 33 and 34: 21 complicated by a variable viscos
- Page 35 and 36: 2J Schultz-GrQnow (174) used a dime
- Page 37 and 38: 2S The results shm-red that equatio
- Page 39 and 40: Su.bstituti011 of equati 2-22 gives
- Page 41 and 42: 29 In both Newtonian and non-Newton
- Page 43 and 44: 31 for viscous pseudoplas tics at 1
- Page 45 and 46: 33 (2-29 when both the distances ar
- Page 47 and 48: JS Thermometers or thermocouples ar
- Page 49 and 50: .37 2: a in in heat cQ@tent of the
- Page 51 and 52: J9 cooling mediu..:m side, the heat
- Page 53 and 54: 41 ports a value of 3/4-.. He then
- Page 55 and 56: 43 find the effects of one or two o
- Page 57 and 58: 45 The group to the left of the equ
- Page 59 and 60: 47 the highest heat tra...nsfer coe
- Page 61 and 62: 49 A pitched blade turbine gave coe
- Page 63 and 64: SI done on the correlation of heat
- Page 65 and 66: 5J evaluated at the wall temperatur
- Page 67 and 68: ss to (2-46 where ill is the consis
- Page 69 and 70: CHAPTER .2 DEVELOPMENT OF CORRELATI
- Page 71 and 72: momentum" mass" and energy may be ~
0<br />
beeemes negligible fu~d<br />
agaim Newt~nianbehaviGr is ~redieted.<br />
~e equation als~ preaiets a saear-th~ing phenomenon at<br />
intermea.iate shear rates (120). Thus this equatien is very<br />
gGod if a very wide shear-rate range must be aeeurately<br />
pertrayed er if existing data must be extra~olated.<br />
There are a few disadvantages to using the Pewell<br />
Eyring equation.<br />
1. 'Three eORstants must be evaluated.<br />
2. The equation eannet be selved explicitly fer<br />
shear rate.<br />
3.. The eorrelations whieh have been aeveloped<br />
using this equatien ean only be solved using<br />
published graphs.<br />
These are based en two or<br />
three parameters in addition to ~e dimensionless<br />
groups represented by the eeordinates (42,<br />
43) •<br />
The Ostwald-deWaele model, mere eommonly ealled the<br />
"p0wer lawlf is ancempirieal equa.tion whieh aceurately €l.eseribes<br />
the ~lew eurve <strong>of</strong> most pseudeplastie <strong>fluids</strong> ~<br />
the shear rate range most commonly eneountered in industrial<br />
processes.<br />
(2-4<br />
K is named the It~lu.id e0r:lsisteney i:ID.dex" and. is somewhat<br />
a.:m.alogous to the Newt@l!'lian viseesi ty in that it
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