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 |