Calculating Nusselt No. for Natural Gas Pipeline

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Discussion Overview

The discussion revolves around calculating the Nusselt number for natural gas in a buried pipeline, specifically focusing on determining the convective heat transfer coefficient and the temperature distribution within the pipe. The context includes theoretical and practical aspects of heat transfer in fluid dynamics.

Discussion Character

  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant seeks to calculate the Nusselt number and convective heat transfer coefficient for natural gas in a buried pipeline, providing specific data.
  • Another participant questions whether the focus is on the convective coefficient for the outside of the pipeline or the temperature distribution inside the pipe.
  • A participant clarifies their intention to find the temperature distribution inside the pipe, suggesting that the Nusselt number relates to the flow of the fluid rather than the interaction between the wall and the fluid.
  • A later reply provides a general description of the Nusselt number and mentions methods for estimating thermal distribution, emphasizing the need to consider flow characteristics such as whether it is fully developed or in the hydrodynamic entrance region.
  • One participant expresses concern about the lack of differential equations provided in the problem statement.
  • Another participant inquires if this is a homework problem and whether a textbook is available that outlines relevant equations.

Areas of Agreement / Disagreement

Participants express differing views on the focus of the calculation, with some emphasizing the internal temperature distribution and others questioning the assumptions about the flow and heat transfer. The discussion remains unresolved regarding the specific approach to take.

Contextual Notes

Participants note the absence of differential equations in the provided data, which may limit the analysis. There are also assumptions about flow characteristics that have not been explicitly defined.

codicil
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Hello I need to calculate the nusselt number for natural gas in a buried pipeline. My question is how to calculate the convective heat transfer co efficient?
The data is 220000m3/h, pipe ID 35", gas temperature 100C and ground temperature is 4C, gas SG 0.65, k = 0.037 W/m-K, R= 441 J/kg-K, CP = 2016 J/Kg-K, gama = 1.28
 
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codicil said:
Hello I need to calculate the nusselt number for natural gas in a buried pipeline. My question is how to calculate the convective heat transfer co efficient?
The data is 220000m3/h, pipe ID 35", gas temperature 100C and ground temperature is 4C, gas SG 0.65, k = 0.037 W/m-K, R= 441 J/kg-K, CP = 2016 J/Kg-K, gama = 1.28

Do you mean the convective coefficient for the outside of the pipeline? Or are you trying to find a temperature distribution inside the pipe?
 
I am trying to find temperature distribution inside the pipe. I guess nusselt number associate with the flow of the liquid and it take convective heat transfer co-efficient within the fluid and not between wall and fluid, please correct me if I am wrong.
 
Nusselt number's general description: Dimensionless temperature gradient at the surface of a convection flow (not limited to internal flow).

There are several methods of dertermining or estimating the thermal distribution in a fluid traveling through a pipe of a different temperature. you will have to decide if the flow if fully developed or if you are within the hydrodynamic entrance region, and what sort of things you can assume about the flow such as incompressible, laminar/turbulent, constant pipe wall temperature, things like that.

One thing you might look into is the Momentum and Heat Transfer Analogy, a.k.a. the Reynolds Analogy. This analogy can give you an estimate of the fluid's temperature distribution based on its velocity distribution. Otherwise, The differential equation describing the heat flux in the fluid could get you to where you want to go.
 
well that is the problem I was not given any diffrential eq. all I was given is the above data
 
Is this a homework problem? Do you have a textbook of some kind that lays out such equations for you?
 

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