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June 13, 2017, 10:31 |
Nu in CFX
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#1 |
New Member
Ali karimi
Join Date: May 2017
Posts: 12
Rep Power: 8 |
hey guys!
I wanna simulate a heat exchanger with internal and external flow, water flows inside pipe and air outside of it. my problem is I don't know how to calculate Nu number. My reference paper used functions that attached for calculating Nu number please someone help how to calculate Nu in CFX.
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June 13, 2017, 12:18 |
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#2 |
Senior Member
Join Date: Jun 2009
Posts: 1,804
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Your question is very general.
Which type of Nu number are you interested in ? What is the purpose/goal of computing the Nu number at all ? There are several variants of the Nu number, and each has a different formula. Are you interested in the local Nu number or the mean/average Nu to compute total heat transfer rates ? For example, an energy balance for inner flow implies (neglecting kinetic energy for now) Q_wall = Mass Flow * (Static Enthalpy_outlet - Static Enthalpy_inlet) For an average Heat Transfer Coefficient HTC_average * Area Pipes * Appropriate_Delta_T = Q_wall Then, Nu_average = Q_wall * Diameter/ (Area Pipes * Appropriate_Delta_T) Still unanswered questions; therefore, more information specific to your setup is required. Summary: it is not trivial to answer w/o specifics. Hope the above helps somehow |
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June 13, 2017, 13:48 |
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#3 | |
New Member
Ali karimi
Join Date: May 2017
Posts: 12
Rep Power: 8 |
Quote:
So I should enable HTC in expert parameters , my inlet temp is 40c , what value should I set for reference temp in HTC? IMG_20170613_190649.jpg Sent from my SM-N920C using CFD Online Forum mobile app
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June 13, 2017, 16:16 |
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#4 |
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Erik
Join Date: Feb 2011
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Check the FAQs
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