How do you calculate fouling resistance?
How do you calculate fouling resistance?
Typical Fouling Factors
- Alcohol vapors : Rd = 0.00009 (m2K/W)
- Boiler feed water, treated above 325 K : Rd = 0.0002 (m2K/W)
- Fuel oil : Rd = 0.0009 (m2K/W)
- Industrial air : Rd = 0.0004 (m2K/W)
- Quenching oil : Rd = 0.0007 (m2K/W)
- Refrigerating liquid : Rd = 0.0002 (m2K/W)
- Seawater below 325 K : Rd = 0.00009 (m2K/W)
What does fouling factor depend on?
Fouling factor (or dirt factor) definition It is also often referred to as the ‘dirt factor’. It normally depends on the process fluid or service on any side (shell or tube) of the heat exchanger. Fouling or dirt factor is used for calculation of the overall heat transfer coefficient of a heat exchanger.
How does fouling factors affect the performance of heat exchanger?
Fouling increases the overall thermal resistance and lowers the overall heat transfer coefficient of heat exchangers. Fouling also impedes fluid flow, accelerates corrosion and increases pressure drop across heat exchangers.
What is the unit of fouling factor?
Hence the SI unit of fouling factor is m².°C/W. In FPS system: In the FPS system, the unit of the convective heat transfer coefficient is Btu/hr.ft².°F. Therefore unit of fouling factor is given by, Fouling factor=1h−1Btuhr.
What is fouling factor?
The fouling factor represents the theoretical resistance to heat flow due to the buildup of a fouling layer on the tube surfaces of the heat exchanger. In practice, fouling factors are often overstated by the end user in an attempt to minimize the frequency of cleaning.
What is the value of fouling factor for sea water?
Which one is having the highest value of fouling factor? Explanation: Fouling factor for liquid gasoline is 0.0008 while that of clean river, sea water and distilled water are 0.0002, 0.0001 and 0.0001 respectively. Fouling factor = 1/hS.
What does higher fouling factor mean?
The fouling factor represents the theoretical resistance to heat flow due to a build-up of a layer of dirt or other fouling substance on the tube surfaces of the heat exchanger, but they are often overstated by the end user in an attempt to minimise the frequency of cleaning.
How does fouling affect thermal resistance?
The buildup of fouling also reduces the cross-sectional area of the tubes or flow channels and increases the resistance of the fluid passing over the surface. These side effects combine to increase the pressure drop across the heat exchanger, reducing flow rates and aggravating the problem further.
How do you reduce fouling factor?
Tips for Reducing Fouling in Heat Exchangers
- Increase Energy Consumption.
- Control Materials Causing Buildup.
- Select Durable Materials.
- Apply Coatings.
- Perform Regular Cleanings.
- Set up a Treatment System.
What is the significance of NTU?
Basically NTU signifies number of transfer units of heat . high number of NTU shows the heat exchanger is efficient in its task .
What is the unit of fouling factor in SI system Mcq?
Q. | In SI units, fouling factor is expressed in |
---|---|
B. | W/m2°K |
C. | m2°K |
D. | m°K/W |
Answer» a. m2°K/W |