HTFS2001的问题

liuxin · 发表于 2005-3-23 21:25

HTFS2001（四模块解密）的TASC模块计算的再沸器面积与BJAC及PROII的结果差别较大，有谁知道是什么原因？

liuxin · 发表于 2005-3-24 06:32

HTFS2001-TASC计算结果的可信度如何？

tomlu · 发表于 2005-3-24 20:10

请把你的算例和结果传上来,我用正版给你核算.

liuxin · 发表于 2005-3-24 22:59

<

>一路next，只是Tube Pitch:25.4mm，结果见附件。
下面是warning
 TASC RUN ON 24-MAR-2005 14:37 BEGINNING OF RUN 1
INPUT: C:\LOCALS~1\Temp\HYSYS.TAI 
 *** NO PROPERTIES PACKAGE ERRORS OR WARNINGS 
 *******************************************************************************
*** WARNING *** Approximations are made for the tubeside temperature profile in
DESIGN mode. These approximations are reasonable for most cases, but sometimes
the results may be inaccurate for cases which are two phase on the tubeside,
especially if the tubeside heat transfer coefficient varies significantly.
Please check the design in CHECKING mode. 
 *******************************************************************************
*** WARNING *** For the specified shell type TASC uses averaging procedures for
the tubeside temperature profile when there are more than 4 tube passes. There
may be some loss of accuracy when these procedures are applied to two-phase
tubeside flows. 
 *******************************************************************************
*** WARNING *** At some point(s) the crossflow fraction in the shellside flow
model was less than 30% and the shell/baffle leakage fraction was greater than
35%. This condition is likely to give poor shellside heat transfer, and should
be avoided. There may also be an adverse effect on the mean temperature
difference at low shellside Reynolds numbers. 
 *******************************************************************************
*** WARNING ***
REASON: Boiling calculation - mixture correction parameter 1.135 is greater
than the maximum allowable value of 1.0.

PROGRAM ACTION: Parameter set to 1.0 and calculation continued.

USER ACTION: Check data and treat results with caution. 
 *******************************************************************************
*** WARNING ***
REASON: Liquid/vapour density ratio of 2433.5 in critical heat flux correlation
for tubeside boiling out of normal range (2.90 to 1623.2).

PROGRAM ACTION: Calculation continued using actual density ratio.

USER ACTION: Check data and treat results with caution. 
 *******************************************************************************
*** WARNING ***
REASON: The critical heat flux was exceeded in the calculation at qualities
between 0.000479 and 0.2530. At the point with a quality of 0.000479 the
calculated heat flux was 12230. W/m2 and the critical heat flux was 0.0 W/m2.

PROGRAM ACTION: Since you have requested a post-dryout heat transfer
calculation, the program limits the calculated heat flux to the critical heat f
lux.

USER ACTION: You should consider revising the design or the process conditions.
 
 *******************************************************************************
*** WARNING ***
REASON: The tubeside critical heat flux could not be calculated between
qualities of 0.000479 and 0.2530, probably because the program has predicted
fully stratified flow in a horizontal tube.

PROGRAM ACTION: It was therefore not possible to do a calculation of
post-dryout heat transfer (if requested) at these conditions, and the
program has used the normal boiling heat transfer coefficient.

USER ACTION: Note that the program has predicted fully stratified flow in a
horizontal tube. It may be desirable to increase the tubeside mass flux. 
 *******************************************************************************
*** WARNING *** Consider using a V type rear head (30?cone) to avoid excessive
nozzle/cylinder thickness due to having to reinforce a large opening. 
 *******************************************************************************
*** WARNING *** The shell-side design pressure is greater than that of the tube
side. You may wish to consider putting the high-pressure stream in the tubes to
reduce the thickness of the shell.

liuxin · 发表于 2005-3-25 00:18

<

>壳程压降5KPa，降膜蒸发器，立式，逆流。TAI文件见附件。
结果：
TASC Version 5.00 - DESIGN

Geometric details
Shell type / series / parallel AEL 1 1
Shell diam / tube length / total area 254 mm 1951 mm 8.52 m
No of passes / no of plain tubes 1 73
Tube id / od / pitch (pattern) 14.83 mm 19.05 mm 25.4(30) mm
No of baffles / pitch / cut 35 50.8 mm 15 %
Process details
Total mass flowrates shell / tube 138.1 kg/h 951.3 kg/h
Inlet temperature shell / tube 201.37 152.23
Outlet temperature shell / tube 201.22 187.03
Inlet / outlet quality shell / tube 1.0 / 0.0 0.0 / .2531
Results
Total pressure drop shell / tube 0.0036 bar 0.0059 bar
Velocity highest shell xflow / tube 1.78 m/s 14.97 m/s
Coefficients shell / tube / wall 10493 W/m 316 W/m 20391 W/m
Fouling coeff shell / tube W/m W/m
Overall coefficient clean / dirty / service 302.2 W/m 302.2 W/m 286.3 W/m
Heat load / eff wtd mtd 74.364 kW 31.31
Area ratio (act/req) 1.055 
warning:
 TASC RUN ON 24-MAR-2005 16:06 BEGINNING OF RUN 1
INPUT: C:\DOCUME~1\wyl\LOCALS~1\Temp\HYSYS.TAI 
 *** NO PROPERTIES PACKAGE ERRORS OR WARNINGS 
 *******************************************************************************
*** WARNING *** The falling film evaporator option is only available when the
cold stream is on the tubeside and there is one tube pass in a vertical
exchanger. The normal boiling calculations will be applied to this run. 
 *******************************************************************************
*** WARNING *** Approximations are made for the tubeside temperature profile in
DESIGN mode. These approximations are reasonable for most cases, but sometimes
the results may be inaccurate for cases which are two phase on the tubeside,
especially if the tubeside heat transfer coefficient varies significantly.
Please check the design in CHECKING mode. 
 *******************************************************************************
*** WARNING *** For the specified shell type TASC uses averaging procedures for
the tubeside temperature profile when there are more than 4 tube passes. There
may be some loss of accuracy when these procedures are applied to two-phase
tubeside flows. 
 *******************************************************************************
*** WARNING *** At some point(s) the crossflow fraction in the shellside flow
model was less than 30% and the shell/baffle leakage fraction was greater than
35%. This condition is likely to give poor shellside heat transfer, and should
be avoided. There may also be an adverse effect on the mean temperature
difference at low shellside Reynolds numbers. 
 *******************************************************************************
*** WARNING ***
REASON: Liquid/vapour density ratio of 2433.5 in critical heat flux correlation
for tubeside boiling out of normal range (2.90 to 1623.2).

PROGRAM ACTION: Calculation continued using actual density ratio.

USER ACTION: Check data and treat results with caution. 
 *******************************************************************************
*** WARNING *** Consider using a V type rear head (30?cone) to avoid excessive
nozzle/cylinder thickness due to having to reinforce a large opening. 
 *******************************************************************************
*** WARNING *** The shell-side design pressure is greater than that of the tube
side. You may wish to consider putting the high-pressure stream in the tubes to
reduce the thickness of the shell.

liuxin · 发表于 2005-3-25 00:21

同一换热器，两个结果相差较大。（前一个取缺省值，后一个如上，同样Tube Pitch:25.4mm）

liuxin · 发表于 2005-3-25 08:04

HTFS的计算很有意思，当设定最小管长时，计算出的管数不变，对同种物流情况就会得出不同的换热面积，为什么？

Arabicus · 发表于 2005-3-26 06:30

<DIV class=quote>以下是引用liuxin在2005-3-25 0:04:25的发言：
HTFS的计算很有意思，当设定最小管长时，计算出的管数不变，对同种物流情况就会得出不同的换热面积，为什么？</DIV>
<

>
这里不是说的很明白的吗？
*******************************************************************************
*** WARNING *** Approximations are made for the tubeside temperature profile in
DESIGN mode. These approximations are reasonable for most cases, but sometimes
the results may be inaccurate for cases which are two phase on the tubeside,
especially if the tubeside heat transfer coefficient varies significantly.
Please check the design in CHECKING mode. 
也就是说在有相变的情况下，DESIGN模式是做了一定的简化的，所以结果必须带入CHECKING模式下面做检测，因为CHECK和SIMU模式是严格的按照相平衡做热力计算的
您所遇到的问题可以归结为DESIGN模式的非精确计算问题 [em13]

liuxin · 发表于 2005-3-26 22:50

<

>谢谢！CHECKING模式下也会出现WARNING，在HYSYS模拟中有THEED组分，可能此组分库中物性不全，在HYSYS中的换热器核算模式也会不收敛，有时即使收敛压降也相当大。PRO/II和PLUS中没有此组分，在BJAC中用C12H12N2代替也会出现警告，可能是物性问题吧。有些换热器设计时还会出现管程和壳程热负荷不一致的情况，这可是HYSYS生成的数据呀。记得过去用PRO/II核算方式设计换热器，冷凝器、再沸器可以挂到塔上，能够给出TEMA形式的核算数据，很方便，给个系数用到实际中都没问题，现在软件多了，算来算去反而感到不踏实了，郁闷呢。

HTFS2001的问题

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