## 管壳换热器英文文献和中文翻译

Multiple shell and tube heat exchangers in the series are employed to handle the temperature cross in the chemical process industries. Depending on the degree of temperature cross, certain number of heat exchangers (either E or F shell type)
Multiple shell and tube heat exchangers in the series are employed to handle the temperature cross in the chemical process industries. Depending on the degree of temperature cross, certain number of heat exchangers (either E or F shell type) need to be connected in series such that the temperature cross in each exchanger is within allow-able limit. Determination of the number of exchangers for the given terminal temperatures is essential during heat exchanger design phase. In this paper, using ﬁnite difference calculus, modeling has been done to calculate the number of shells required for both E and F shell cases. In addition, equations are developed to determine hot and cold ﬂuid temperature proﬁles across all heat exchangers. Design procedure is illustrated with the help of a case study and the capital cost of both cases is compared. Issues related to E shell and F shells are also discussed.17091
Keywords: Multiple shells in series; Heat exchanger design; Temperature cross; E shell; F shell; Finite difference
1. Introduction
There are several shell conﬁgurations designated as E, F, G, H,
J, K and X by the Tubular Exchanger Manufactures’ Associa-
tion Inc. These are described in detail in literature (Perry and
Green, 1997). E shell is a single-pass shell, and the number
of tube passes may be one or multiples of two (two is most
common). The shell side ﬂuid enters at one end and leaves
the other end of the opposite side. F shell is a two-pass shell
that has a longitudinal bafﬂe piding the shell into two com-
partments, shell ﬂuid enters at one compartment, travels the
entire length of the shell through that compartment, turns
around and ﬂows through the another compartment of the
shell and ﬁnally leaves at the same end of the other side.
The number of tube passes for F shell may be two or mul- 源自六"维%论:文*网!加7位QQ324'9114 www.lwfree.cn
tiples of four (four is most common). Considering ﬁrst the
1–2 heat exchanger in Fig. 1(a), the tube ﬂuid in the ﬁrst tube
pass is in parallel with the shell ﬂuid, and in the second tube
pass the tube ﬂuid is in the counter ﬂow with the shell ﬂuid.
Hence, the log mean temperature difference (LMTD), which
applies to either parallel or counter ﬂow but not to a mix-
ture of both types, cannot be used to calculate the true oreffective mean temperature difference (EMTD) without cor-
rection. Similarly for 2–4 heat exchanger, as may be seen in
Fig. 1(b), contact between shell ﬂuid and tube ﬂuid is a mix-
ture of both parallel and counter ﬂows and hence correction
factor is necessary to get the EMTD. This EMTD is generally
obtained by multiplying LMTD of true counter current ﬂow
by a ﬂow correction factor (FT). This factor is correlated in
terms of two dimensionless ratios, R and P by Nagle (1933)
and Underwood (1934). For instance, derivations can be found
in Kern (1997) and following assumptions were made dur-
ing the derivation: stream ﬂows are at steady state, overall
heat transfer coefﬁcient and speciﬁc heat remain constant
throughout the exchanger, there is no phase change and heat
losses are negligible. Eqs. (1) and (2), Kern (1997) are used
to calculate FT for 1–2 exchanger and FT for 2–4 exchanger,
respectively.
For 1–2 heat exchangerNomenclature
a, b, c cost law coefﬁcients
bc cost of base line exchanger
A heat transfer area (m2)
AT heat transfer area of total exchangers (m2)
B arbitrary constant
C capital cost of total heat exchangers
cp speciﬁc heat of cold ﬂuid (kJ/kgK)
Cp speciﬁc heat of hot ﬂuid (kJ/kgK)
Cpn average speciﬁc heat of hot ﬂuid for nth
exchanger (kJ/kgK)
Eb f.o.b. price of total heat exchangers on January 管壳换热器英文文献和中文翻译:http://www.lwfree.cn/fanyi/20180107/18633.html
------分隔线----------------------------