|
Significance of flow-rates |
|
Flow-rates and any change in flow-rates have different
effects on Q and U values. Following are the effects:
|
Changes |
Effects |
|
If hot fluid flow rate is increased |
The ΔP of hot
fluid across the heat exchanger will increase.
The inlet P
of hot fluid will increase
The ΔT of hot
fluid will decrease
The ΔT of
cold fluid will increase
The Q value
will increase |
|
If hot fluid flow rate is decreased |
Vice-versa of
the above effects |
|
If cold fluid flow rate is increased
If cold fluid flow rate is increased |
The ΔP of
cold fluid across the heat exchanger will increase.
The inlet P
of cold fluid will increase
The ΔT of
cold fluid will decrease
The ΔT of hot
fluid will increase
The Q value
will increase
The
fouling/scaling propensity of Cold fluid will decrease
The flow induced corrosion/erosion may increase |
|
If cold fluid flow rate is decreased |
The ΔP of
cold fluid across the heat exchanger will decrease.
The inlet P
of cold fluid will decrease
The ΔT of
cold fluid will increase
The Q value
will decrease
The fouling/scaling propensity of Cold fluid will increase Avoid such
situations |
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Introduction |
Combined heat transfer process |
Heat transfer in cooling tower |
Variables affecting performance of CT heat transfer |
Heat transfer within
cooling system (heat exchanger) |
Types of heat exchanger |
Basic design
procedure and theory |
Designing a test heat exchanger |
Log Mean Temperature
difference | L.M.T.D. Correction factors |
Overall heat transfer coefficient |
Elaborated method for calculating U values |
Effect of scale formation |
Condensation of steam |
Condenser, where the hot fluid temperature varies |
Significance of pressure |
Significance of flow rate |
Methods of checking steam
condenser performance |
Common conversion factors
|