C i Af (Cexc Cpump,T ) Cpump,s )
min
max
c mt e
Af [(Ca Cb A ) (Ce Cf ( ΔPt ) ) (34)
t t t (40)
min max
t
(Ce Cf ( s ΔPs )e )]
s
where Cexc, Cpump,t and Cpump,s are the capital costs for the exchanger, tube side and shell side pumps, respectively。
1
s s s (41)
High velocities will give high heat transfer coef- ficients but also a high pressure drop。 The velocity must be high enough to prevent any suspended so- lids settling, but not so high as to cause erosion。 High velocities will reduce fouling。 Plastic inserts are some- timesused to reduce erosion at the tube inlet。 Typical
design velocities are given below [15]。
Cod
( mt ΔP ms ΔP )C H
(35)
Liquids。 Tube-side, process fluids: 1 to 2 m/s,
t s
Ctot Ci Cod (36) This new cost calculation is used in case study 3
to have a same basis for comparison of performance of SA approach and GA approach。
maximum 4 m/s if required to reduce fouling; water: 1。5 to 2。5 m/s; shell-side: 0。3 to 1 m/s。
Vapors。 For vapors, the velocity used will de- pend on the operating pressure and fluid density; the lower values in the ranges given below will apply to high molecular weight materials; vacuum: 50 to 70
m/s; atmospheric pressure: 10 to 30 m/s; high pres- sure: 5 to 10 m/s。
In this work, the following constraints were im- posed on objective function:
where x is the vector of optimization variables (Table 1)。 The set of constraints g(x) corresponds to the inequalities given by Eqs。 (37)–(43)。
For implementation of the SA algorithm, we
used a penalty function in the objective function, to
1 vt 2 m/s and 0。3 vs
Service constraints
1 m/s
provide the following objective function to be mini- mized [16]。
The hydraulic requirements of the service are represented by upper bounds on the pressure drop of both streams:
Obj (x ) Ctot (x ) penalty(x ) (44)
The penalty function accounts for the violation of the constraints such that:
ΔP ΔPmax (42) 模拟退火技术来设计英文文献和中文翻译(7):http://www.youerw.com/fanyi/lunwen_100221.html