Mutual Thermal Resistances between Pipe Layers

In summary, the reference provides formulations for mutual thermal resistances between layers of a buried pre-insulated pipe, specifically between water-insulation, ground-surrounding, and insulation-ground. However, the question asks for thermal resistances between water-steel, steel-insulation, insulation-ground, and ground-surrounding. The suggested references do not directly address this question, but provide information on heat transfer analysis through multi-layered cylindrical geometries and heat transfer coefficients. It is suggested that the heat transfer coefficient at the wall can be found using empirical relations involving Reynolds and Prandtl numbers, such as the Dittus-Boelter equation. However, this may not be applicable if the water flowrate is high enough to cause conduction-l
  • #1
HumanistEngineer
18
2
TL;DR Summary
Mutual thermal resistances between layers of a cylinder (either a pipe or a storage tank) in order to obtain heat transfer between these sections (e.g. from water to steel, steel to insulation, insulation to the ground and vice versa).
Ref: Palsson, Halldor | Analysis of Numerical Methods for Simulating Temperature Dynamics in District Heating Pipes - please check pg. 62 at LINK (CLICK!)

INTRO: In this reference, the mutual thermal resistances between layers as water-insulation, ground-surrounding, and insulation-ground are defined for a buried pre-insulated pipe, figure and formulations given below:
FIGURE:
244535

FORMULATIONS:
244536


QUESTION: I want to improve the model given in this reference by studying the layers as water, steel, insulation, and ground so I need to obtain the mutual thermal resistances between water-steel, steel-insulation, insulation-ground, and ground-surrounding. I couldn't find a reference describing how to find the thermal resistances between layers of a cylinder such as between water and steel and others. Can any of you help me either by giving formulations or by guiding me to a reference?

More details (Ri and Rg as given in the formulation above (3c)):
244537
 
  • Like
Likes berkeman
Engineering news on Phys.org
  • #3
Mech_Engineer said:
Heat transfer analysis through a multi-layered cylindrical geometry is a common topic, you might just need to look for the right key words.

Here is one paper I found on the subject: https://web2.clarkson.edu/projects/subramanian/ch330/notes/Conduction in the Cylindrical Geometry.pdf

This topic is also covered in college-level heat transfer courses: https://www.sfu.ca/~mbahrami/ENSC 388/Notes/Staedy Conduction Heat Transfer.pdf

Thank you Mech_Engineer. But I don't think that such references are good as answer to my question. I want to find the temperature of (i.e.) insulation so I need this, as termed by the reference, the mutual thermal resistance between the layers (for example between water and insulation (as well as between insulation and the ground). Meanwhile, I need to find the temperature of sorrounding ground (its temperature gets affected by the water temperature as result).
 
  • #4
Usually the heat transfer coefficient at the wall (such as between the water and the steel tube) would be found from empirical relation involving Reynolds and Prandtl numbers (see for example, Dittus-Boelter). I'm not sure why that doesn't seem to appear in your referenced text. Maybe (?) the water flowrate is high enough that the heat transfer is conduction limited (so that the convection coefficient isn't significant)?
 
  • Like
Likes HumanistEngineer

1. What is the purpose of calculating mutual thermal resistances between pipe layers?

The purpose of calculating mutual thermal resistances between pipe layers is to determine the amount of heat transfer between different layers of pipes. This information is important for designing efficient and effective piping systems, as well as for predicting and controlling heat loss or gain.

2. How do you calculate mutual thermal resistances between pipe layers?

Mutual thermal resistances between pipe layers can be calculated using the thermal conductivity and thickness of each layer. The formula for calculating thermal resistance is R = d/k, where R is the thermal resistance, d is the thickness of the layer, and k is the thermal conductivity. The reciprocal of this value gives the mutual thermal resistance between two layers.

3. What factors affect mutual thermal resistances between pipe layers?

The main factors that affect mutual thermal resistances between pipe layers are the thermal conductivity and thickness of each layer, as well as the contact resistance between the layers. Other factors that may have an impact include the material properties of the pipes, the temperature difference between the layers, and any insulation or external heat sources.

4. How can mutual thermal resistances between pipe layers be reduced?

Mutual thermal resistances between pipe layers can be reduced by increasing the thermal conductivity of the layers, decreasing the thickness of the layers, or improving the contact between the layers. Additionally, using insulation materials can help to reduce heat transfer between the layers and improve overall thermal efficiency.

5. Why is it important to consider mutual thermal resistances between pipe layers in piping system design?

Considering mutual thermal resistances between pipe layers is important in piping system design because it affects the overall thermal performance of the system. Neglecting to account for these resistances can result in inefficient heat transfer, increased energy consumption, and potential system failures due to thermal stress. Properly accounting for mutual thermal resistances can help to optimize the design and ensure the system operates efficiently and reliably.

Similar threads

  • General Engineering
Replies
4
Views
938
  • Electromagnetism
Replies
16
Views
2K
  • Mechanical Engineering
Replies
13
Views
15K
  • Engineering and Comp Sci Homework Help
Replies
5
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
Replies
152
Views
5K
Replies
3
Views
12K
Replies
9
Views
8K
  • General Engineering
2
Replies
35
Views
90K
Replies
3
Views
12K
Back
Top