Calculating Grashof's Number for Natural Convection

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SUMMARY

The discussion focuses on calculating Grashof's number (Gr) for natural convection involving a heated plate at temperature Tp and surrounding air at temperature Ta. The film temperature (Tf) is defined as Tf = 0.5(Tp + Ta). The formula for Grashof's number is provided as Gr = (βgL³ΔT)/ν², where ΔT represents the temperature difference (Tp - Ta) and β is the coefficient of thermal expansion. The participant questions the appropriate values for ΔT and β, seeking clarification on their application in the formula.

PREREQUISITES
  • Understanding of natural convection principles
  • Familiarity with thermodynamic properties, specifically thermal expansion coefficient (β)
  • Knowledge of fluid dynamics, particularly the significance of Grashof's number
  • Basic grasp of heat transfer concepts
NEXT STEPS
  • Research the definition and calculation of the thermal expansion coefficient (β) for various fluids
  • Study the derivation and application of Grashof's number in natural convection scenarios
  • Explore the significance of film temperature (Tf) in heat transfer calculations
  • Investigate resources on natural convection, including textbooks and academic papers
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Engineers, physicists, and students involved in thermal analysis, fluid dynamics, and heat transfer applications will benefit from this discussion.

lazypast
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HI

when dealing with natural convection, we use grashof's number. suppose we have a heated plate of temperature Tp. and heat being transferred to surrounding air by convection, air of temp Ta.

So film temp is Tf = 0.5(Tp + Ta)

If grashofs numbers, Gr = \frac { \beta gL^3 \delta T}{\nu^2}

im wondering what \delta T and what \beta we use.

thanks
 
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