How To Calculate Plate Type Heat Exchanger
The plate heat exchanger is a new type of high-efficiency heat exchanger formed by stacking a series of metal plates with a certain corrugated shape. A thin rectangular channel is formed between the various plates to exchange heat through the plate. Compared with the conventional shell-and-tube heat exchanger, the heat transfer coefficient is much higher under the same flow resistance and pump power consumption, and there is a tendency to replace the shell-and-tube heat exchanger within the applicable range.
Application
Hot side- 65M3/H, Inlet :90 ℃,Outlet:45℃,Cold side-58.5M3/H Inlet:25℃,Outlet:75℃,Pressure:100Kpa
physical parameters
Hot fluid: Density(ρ1)=979.1kg/m3 Specific heat(cp1)=4.185KJ(kg. ℃)
Cold fluid: Density(ρ1)=988.1kg/m3 Specific heat(cp1)=4.174KJ(kg. ℃)
Design process
1. Heat load (Q)=qm1 .cp1(t1’- t1”)=(65/3600)x979.1x4.185x(90-45)=3329.25Kw
2. Logarithmic mean temperature difference
△Tm=（△T1-△T2）÷㏑（△T1/△T2)=(20-15) ÷㏑(20/15)=17.38℃
3.The K-Value(heat transfer coefficient)
water and water:2000-7000w/m2℃
water and oil:150-900w/m2℃
Steam and water:1000-2000w/m2℃
water and milk:1000-4000w/m2℃
4.Heat transfer area A Q=AK △Tm A=Q/ △Tm.K=3329250W/17.38.4100=46.72 ㎡
5.Confirm the model and the gasket
Following the flow rate ,we check it require the DN100 connection, Then our model is BR10MBL, The heat transfer area is 0.3㎡.so the model is : TL10M-10-157-E, with 157 pcs plate
The gasket is according to the temperature and the fluid
NBR design temperature 110 ℃
EPDM design temperature 150 ℃
6.Check the velocity in the connection and the two plate
Connection velocity W1 ≤ 3.5-4.5m/s
Velocity between two plate=Flow rate/Pass x(corrugation depth-plate thickness)x plate width=0.1-0.4m/s
Then for this application W1=4q/3600. π D2=4x65/(3600x3.14x0.12)=2.26m/s , it ok for this connection
Velocity between two plate=(65÷3600)/(39x0.0034x0.369)=0.37m/s, this is good.
So confirm the model is: TL10M-10-157-E
Pass: 2x39/2x39
Plate heat exchanger pressure drop
About the pressure, General, the customer advice less than 150Kpa. The pressure according the Velocity between two plate, if the velocity is quickly , the heat transfer coefficient is high, the pressure will so big. The designer will following the pressure drop requirement to adjust the heat transfer area.