Range of fluid flow velocity in the heat exchange tube
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The medium flowing inside the heat exchange tubes is water; what happens if the flow velocity is greater than 1.8 m/s or less than 1.0 m/s? What are the actual consequences in practical use? Some technical documents specify a range of 0.5–3.0 m/s – is this range too wide? I would appreciate guidance from those with experience
When the flow velocity is less than 1 m/s, the heat transfer coefficient decreases; increasing the heat exchange area raises the manufacturing costs. When the flow rate is greater than 1.8 m/s, the heat transfer coefficient increases, which reduces costs; however, the resistance also rises, increasing operating expenses. Therefore, an appropriate flow rate should be selected to make the heat exchanger more economical
I have been studying the process calculations for heat exchangers recently, and I found that the flow rate of water is generally taken to be between 1.0 and 1.3; this is based on empirical data, and sometimes the choice depends on the actual operating conditions
For light pipes, a value of 1.5–2 m/s is generally used
I remember that in previous textbooks on chemical engineering principles, it was said that the empirical value should be taken between 1 and 3 m/s! Depending on the flow velocity, the flow state within the pipe changes; to increase the heat transfer coefficient, turbulence is generally required inside the pipe! ————Personal advice!
The flow rate of water should be between 1.0 and 1.5; a low flow rate can lead to under-scale corrosion when the water is dirty, while a high flow rate is not economical.
The value range of 0.5~3 m/s is derived from past experience and the Reynolds number formula Re=duρ/μ; generally, turbulence occurs when Re>4000, and the heat transfer efficiency in turbulent media is better than that in laminar flow