Table of Contents
- 1 What is the cleanliness factor?
- 2 What is meant by the fouling factor of a heat exchanger?
- 3 What is the condenser efficiency?
- 4 How does fouling factors affect the performance of heat exchanger?
- 5 Does fouling factor depend on temperature?
- 6 What is the fouling factor of a heat exchanger?
- 7 What are the variables of a heat exchanger?
What is the cleanliness factor?
The cleanliness factor is the factor applied to the clean heat transfer coefficient as an allowance for fouling. The common cleanliness factor used for turbine exhaust surface condensers is 85\% clean, which indicates 17.6\% excess surface area. Additional surface area increases the capital cost.
How do you calculate cleanliness factor?
The cleanliness factor (CF), is an alternate measurement of relative degradation in exchanger performance. CF=Ud/Uc ×100 CF is closed to 100 for a clean exchanger and decrease over time as the exchanger fouls.
What is meant by the fouling factor of a heat exchanger?
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 do you calculate fouling factor?
Heat exchanger fouling is caused by a variety of reasons such as corrosion, precipitation, accumulation of dirt or particles, accumulation of biological material etc….Typical fouling factor values.
Fluid | Fouling Factor [(h⋅ft2⋅°F)/Btu] |
---|---|
Light gas oil | 0.002 |
Heavy gas oil | 0.003 |
Heavy fuel oil | 0.005 |
What is the condenser efficiency?
The thermal efficiency of a condenser is defined as the ratio of actual rise in temperature of cooling water to the maximum possible rise.
How do you clean a fouling heat exchanger?
Mounting the heat exchanger vertically can also minimize the effect as gravity pulls any particles out of the heat exchanger away from the heat transfer surface even at low velocity levels. Deposition fouling is normally removed mechanically by brushing or scraping.
How does fouling factors affect the performance of heat exchanger?
Fouling may significantly impact the thermal and mechanical performance of heat exchangers. 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.
How does fouling factors affect heat transfer?
The deposition of any undesired material on heat transfer surfaces is called fouling. 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.
Does fouling factor depend on temperature?
Fouling factors for corrosion fouling show a peak value as temperature increases; at low temperature, the corrosion rate increases with temperature but the corrosion requires the presence of dissolved oxygen and this dissolved oxygen content is reduced at higher temperatures due to the decreasing solubility of oxygen …
How do you reduce fouling factor in heat exchanger?
The best way to avoid particulate fouling is to keep the cooling water clean and thereby prevent particles from entering the heat exchanger. However, in all cooling systems, and especially when using open cooling systems (with cooling towers), there will always be particles present in the cooling water.
What is the fouling factor of a heat exchanger?
It forms a very small coating that adds resistance to heat transfer. The fouling factor adds surface area to the heat exchanger so it can continue to meet the required capacity even though the tubes are coated or fouled. Why Are Fouling Factors Expressed in Thousandths or Ten Thousandths?
How do you clean a heat exchanger?
Dirty deposits on the heat exchanger walls can be cleaned by either mechanical or chemical methods. Chemical cleaning – Solid deposits which are weakly attached to the exchanger surface can be either washed with water or flushed with steam. Other dirt can be chemically cleaned using suitable solvents or weak acid solutions.
What are the variables of a heat exchanger?
The variables are the U value and the surface area of the heat exchanger. As the U value becomes smaller, the surface area required to do the job goes up. The U value is the inverse of the resistance in the heat exchanger to heat transfer. The U value is very dependent on the fluid type, the velocity, and the materials of construction.
What is the cleanliness factor in Hei?
This is not an official answer, but as I understand it, the cleanliness factor in HEI relates to a percentage of the surface area of a condenser considered to be out of service due to being fouled, and the performance is predicted on that basis. If the tubes never become dirty, then the condenser has X (the cleanliness factor) more surface area.