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發(fā)表于 2008-2-15 14:08:16
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COOLER c8 `5 h8 J, D1 k5 }1 [# f
SELECTION
$ {4 c8 ?1 [2 r$ a5 P5 U1 {Designation:8 X. }0 l( R% u2 Z' ?
PV = Power loss [kW]
# J. b' p0 y- g& MP01 = Specific cooling capacity [kW/°C]
/ a7 s( U @8 d2 e: k- |0 z% D' S4 LV = Tank contents [l]
% V; d4 t; Y) J( } Mρoil = Density of the oil [kg/l]
/ e0 |4 K& B) `( z9 B' Z/ pfor mineral oil: 0.915 kg/l$ x' T- r5 b2 r: s3 J
Coil = Specific heat capacity [kJ/kgK]0 A( ^" o5 ~2 N1 @
for mineral oil 1.88 kJ/kgK
8 }1 g3 O1 r! i1 ^4 E∆T = Temperature increase in the1 F$ u. d0 `) D& }4 O
system [°C]
) J* F& S" |! A" J, u9 \7 w1 ut = Operating time [min]
3 K& g. W9 }" i2 U) ET1 = Desired oil temperature [°C]
/ }1 x8 v* S1 H$ ]! X2 {T3 = Ambient temperature [°C]
0 U t+ J3 n6 p- vExample 1:0 ]/ j; r; R$ Q( l$ R4 \8 F! Y
Measurement of the power loss# J- x# _4 D2 D0 V
on existing units and machinery.3 W! `! V0 o: {! y/ U2 `' n) t
For this method the temperature: P, b% @7 T: [4 F: ?, l' f
increase of the oil is measured
4 a* e6 e0 c, z: Y4 V8 dover a certain period. The power5 M& n q5 K' q- p# x
loss can be calculated from the) _1 W) h6 x; ~2 V# z5 R2 J
temperature increase.- O# P3 {6 M. g- ]1 m
Parameters:
& ~2 z7 {( I7 B7 eThe oil temperature increases% ~7 ^# K; O* C5 j2 R
from 20 °C to 45 °C over8 { m2 c0 B+ M( M
15 minutes.
0 c8 X- x h/ Z& V/ GThe tank contains 100 l.
5 u2 b1 f# Y0 ]Heat to be dissipated:4 F! n+ f( Y, W
PV =（∆T × C oil × ρoil × V）/t × 60 [kW]
/ `! g" C1 s8 A
* d# V4 e6 V9 x: }, VPV =25 × 1.88 × 0.915 × 100 / (15 × 60 )* b# J+ |+ J7 x, d
= 4.78 [kW], v9 n4 e' P% U4 m
Cooler selection:3 s" I# c- s( t3 t7 c" Z% ^& ^
– Desired oil temperature: 60 °C( }4 d% }$ N7 v# l5 k: @
– Ambient temperature air: 30 °C
2 C/ u4 H5 u, f, \: E$ r @& D+ h3 y$ U' n
P01 =PV / (T1 - T3 ) [kW/°C] =0.159, f6 U g Q* L* L
A 10% safety margin is
/ c/ V" n& `9 y" g7 N7 z! p0 yrecommended to allow for
$ K) A% f8 Q$ G6 telement contamination, and: f W; `' @# I
therefore the specific power is:
2 s0 R7 C* W8 D3 G( xP01 × 1.1 = 0.175 kW/°C.6 q7 X9 \' [' n1 t7 t$ x: m
The power loss 0.175 kW/°C must
/ l6 [) K2 i" {6 D5 obe dissipated by an oil cooler.
2 \! ~4 t" ~3 p% NSuggestion:6 z9 |% x: s/ Z4 @/ s) q
–Cooler OK-ELH2 - 3000 rpm,
2 `. }: z' b/ l8 e( u/ QP01 = 0.20 kW/°C at 80 l/min
0 I. L9 w% Q9 `$ `' y* k: |" o1 ~* Z; q4 q1 Z9 d
7 C7 D# Z; D! f5 j/ r, ~我發(fā)了一段在上面！ |
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