换热器的计算---请教
最近单位上新的项目,要选择换热器,但是如何计算?板式和管式有啥区别? 管式的不好,建议选用板式的。 管式的冷却面积没有板式冷却面积大 可以查阅化工版的机械设计手册第4册上面有详细的介绍换热面积的算法 板式的换热效率高,不过最好选择好一些的制造厂家.小的可以用管式的划算. 这得看你需要得散热功率是多大,一般大的用板式散热器 COOLERSELECTION
Designation:
PV = Power loss
P01 = Specific cooling capacity
V = Tank contents
ρoil = Density of the oil
for mineral oil: 0.915 kg/l
Coil = Specific heat capacity
for mineral oil 1.88 kJ/kgK
∆T = Temperature increase in the
system [°C]
t = Operating time
T1 = Desired oil temperature [°C]
T3 = Ambient temperature [°C]
Example 1:
Measurement of the power loss
on existing units and machinery.
For this method the temperature
increase of the oil is measured
over a certain period. The power
loss can be calculated from the
temperature increase.
Parameters:
The oil temperature increases
from 20 °C to 45 °C over
15 minutes.
The tank contains 100 l.
Heat to be dissipated:
PV =(∆T × C oil × ρoil × V)/t × 60
PV =25 × 1.88 × 0.915 × 100 / (15 × 60 )
= 4.78
Cooler selection:
– Desired oil temperature: 60 °C
– Ambient temperature air: 30 °C
P01 =PV /(T1 - T3) =0.159
A 10% safety margin is
recommended to allow for
element contamination, and
therefore the specific power is:
P01 × 1.1 = 0.175 kW/°C.
The power loss 0.175 kW/°C must
be dissipated by an oil cooler.
Suggestion:
–Cooler OK-ELH2 - 3000 rpm,
P01 = 0.20 kW/°C at 80 l/min
我发了一段在上面!
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