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# What are the calculation methods of the plate heat exchanger selection?

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Calculation method and formula of plate heat exchanger selection

1) Find the heat load Q

Q = G. ρ. CP. Δt

+ ~ + ~, X6 C% Y

(2) Find the inlet and outlet temperature of the hot and cold fluid 3 O% d (k; a4 ~ (J! Z

6 B1 O0 R # E (k% ^: _5 E4 H

t2 = t1 + Q / G. ρ.

(3) Flow of hot and cold fluid 4 c. M7 S \$ K5 @） D / v

% C5 I3 o8 j: b

(T2-t1 9 i5 x I,? 'N

9 i1 A7 ~ 2 R; z4 M0 J1 c "Q \$ w

(4) Find the average temperature difference Δtm

!! R6 S'c9? _% N / y (U6 f (B: F

Δtm = (T1-t2)-(T2-t1) / In (T1-t2) / (T2-t1) or Δtm = (T1-t2) + (T2-t1) / 2

(5) Select the plate type

4 k "V" ^ 'G \$ N & A K

If all the plate types are selected, the result analysis is performed.

9 t'W, _) t0 r- v # f + j) V6 V

(6) From the range of K values, calculate the range of plate number Nmin, Nmax

Nmin = Q / Kmax. Δtm. F P． β '^; u / K &? ＆ H8 M1 s

) @ （I0 s5 D; K） N4 K6 E + q V3 Q

Nmax = Q / Kmin. Δtm. F P． β

(7) Take the number of plates N (Nmin≤N≤Nmax)% i'x # n + Y0 C

If N has reached Nmax, do (5).

/ i \$ R, \ & m & [% j Y; Q & A

(8) Take the process combination form of N. If the combination form is taken, do (7).

(9) Find Re, Nu 8 ^% k & R: R8 Y (m (A, Q

Re = W. de / ν5 d0 W: v8 e / k + d &] \$ r

Nu = a1. Rea2. Pra3

* W'J4 V; v3 L! f) M8 X

(10) Find a, K heat transfer area F 9 d (s9 ?! z3 ~ 5 F

a = Nu. λ / de + W- G6] / y / n;?

: B "Y. H5 v.k * |: ^ 3 F

K = 1/1 / ah + 1 / ac + γc + γc + δ / λ0

'f7 | 3 e! l / R （O “m- N9 E & g

F = Q / K. Δtm. β ％ n4 Y # h \$ h) j Y + U9 Y) Q

3 U + ^ / [# s'E6 S

(11) Find the required number of plates NN from the heat transfer area F

!! G # Y) N; x6 d2 I (@

No = F / Fp + 2, A2 \ 'l% u *} \$ d5 p

# I- @ 9 e. years

(12) If N <NN, do (8).

(13) Find the pressure drop Δp

Eu = a4. Rea5

% Q! u \$ [5? 7 N1 K7 h2 R / v2 d

Δp = Eu. ρ. W2. ф

(14) If Δp> Δ allows, do (8); 1 h # ^ * A! u% n / M * E

& M + m5 @ & | 5 [#z ([! V

If Δp≤Δ is allowed, record the result and do (8). : L / R; j8 o (B & f% L

Note: 1. (1), (2), (3) Calculate according to known conditions. {"X, d,], C, @

2. When T1-t2 = T2-t1, Δtm = (T1-t2) + (T2-t1) / 2 8 Q. \ '`/ s'b

6 |; h4 T; x * h \$ \

3． The correction coefficient β is generally 0.7 to 0.9. 1 D: U m \$ n) a

4． Pressure drop correction coefficient ф, single process ф degree = 1 ~ 1.2, two processes, three processes ф = 1.8 to 2.0, and four processes ф = 2.6 to 2.8.

5．a1, a2, a3, a4, and a5 are constant coefficients.

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