Water friction in pipes, hot vs cold?

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SUMMARY

The discussion focuses on the friction loss of tap water in pipes at different temperatures, specifically comparing 5 degrees Celsius and 80 degrees Celsius. The average friction loss is noted as 2 kPa, with a minimal change in density (3%) and a significant increase in viscosity (factor of 4) at higher temperatures. The friction factor for smooth pipes is calculated to be approximately 0.01 at 5 degrees Celsius and 0.012 at 80 degrees Celsius, indicating negligible differences in practical applications. Quick calculations adjusting for density and viscosity are recommended for precise assessments.

PREREQUISITES
  • Understanding of fluid dynamics principles
  • Knowledge of viscosity and density concepts
  • Familiarity with Reynolds number calculations
  • Experience with pipe flow analysis
NEXT STEPS
  • Research the impact of temperature on fluid viscosity using the Arrhenius equation
  • Explore advanced fluid dynamics simulations with software like ANSYS Fluent
  • Learn about the Darcy-Weisbach equation for calculating friction loss in pipes
  • Investigate the effects of pipe material and surface roughness on friction factors
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Engineers, fluid mechanics students, and professionals involved in plumbing design or hydraulic systems will benefit from this discussion on water friction in pipes at varying temperatures.

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I usually use an average number of 2 kPa friction loss for normal tap water in pipes. Does anyone know if this number changes significantly up or down for water which is around 80 degrees C instead of 5?
 
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Well, you're looking at only a 3% change in density but a factor of 4 change in the viscosity. Looking at Reynolds numbers (with a constant velocity and ID), this results in a very similar friction factor. I get about .01 vs. .012 for a smooth pipe. I didn't really go any further with the numbers. It looks though like you're not going to see anything noticible. You might do a couple of quick calcs adjusting your density and viscosity to match the two temps.
 

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