Page 221 - Chemical Process Equipment - Selection and Design

8.6. TYPES OF HEAT EXCHANGERS 791

TABLE 8.lO-(coiltinued)
Across a bank of n tubes deep:

IN-LINE STAGGERED
+IdF
0000
Q5,9 000
0 0-
O0OQA 0 0 0-i

q1=1-z/4a ifbzl
yr=1-n/4ab ifb<l
NU^,^^^^ = df1. = Nu,,,,,/K, n 2 10
[I + (n - l)tl n < 10
Nu,,,,,lKn,
[Nu,,,ow from Eq. !I6)l
=
1
b,in.,ine + (O.7/q1%(b/a - 0.3)/(b/a + 0.7)’l
fn,stag = 1 + 2/36
K = (Pr/Pr,)0.Z5, for liquid heating
K = (Pr/Pr,)o.”, for liquid cooling
K = (T/T,)O.l2, for gases
Subscript w designates wall condition
Banks of radial high-fin tubes: E = (bare tube surface)/(total surface of finned tube)
!n line:
N~ = 0.30 ~~0.62’5~-0.375 r’ 333 , 5<&<12, 5000<Re<105 (29)
p
0
Staggered: a = s,jd, b = sJd, s =spacing of fins
Nu = 0.19(a/b)02(s/d)0.’8(h/d)-o~14 Reo 65Pr0.33 , 100 < Re < 20,000 (30)
Banks of radial low-fin tubes: D=diarneter of finned tube, s =distance between fins,
h = height of fin; following correlation for D = 22.2 mm, s = 1.25 mrn, and h = 1.4 rnm

Nu = 0.0729 , 5000 < Re < 35,000
Nu = 0.137 35,000 < Re < 235,000
Nu = 0.0511 , 235,000 < Re < 1 O6

B. Condensation of Pure Vapors
On vertical tubes and other surfaces; r = condensation rate per unit of periphery

On a single horizontal tube: r= condensation rate per unit length of tube

(continued)