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The Length is the measurement of the distance along the flow direction in a laminar flow scenario within tubes, influencing flow characteristics and heat transfer efficiency. Check FAQs
L=0.04ReDDtPr
L - Length?ReD - Reynolds Number Dia?Dt - Diameter of Thermal Entry Tube?Pr - Prandtl Number?

Thermal entry length Example

With values
With units
Only example

Here is how the Thermal entry length equation looks like with Values.

Here is how the Thermal entry length equation looks like with Units.

Here is how the Thermal entry length equation looks like.

3Edit=0.041600Edit0.067Edit0.7Edit
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Thermal entry length Solution

Follow our step by step solution on how to calculate Thermal entry length?

FIRST Step Consider the formula
L=0.04ReDDtPr
Next Step Substitute values of Variables
L=0.0416000.067m0.7
Next Step Prepare to Evaluate
L=0.0416000.0670.7
Next Step Evaluate
L=2.9999872m
LAST Step Rounding Answer
L=3m

Thermal entry length Formula Elements

Variables
Length
The Length is the measurement of the distance along the flow direction in a laminar flow scenario within tubes, influencing flow characteristics and heat transfer efficiency.
Symbol: L
Measurement: LengthUnit: m
Note: Value should be greater than 0.
Reynolds Number Dia
The Reynolds Number Dia is a dimensionless quantity that helps predict flow patterns in fluid mechanics, specifically for laminar flow in tubes based on diameter.
Symbol: ReD
Measurement: NAUnit: Unitless
Note: Value should be greater than 0.
Diameter of Thermal Entry Tube
The Diameter of Thermal Entry Tube is the width of the tube through which fluid flows, impacting heat transfer efficiency in laminar flow conditions.
Symbol: Dt
Measurement: LengthUnit: m
Note: Value should be greater than 0.
Prandtl Number
The Prandtl Number is a dimensionless quantity that relates the rate of momentum diffusion to thermal diffusion in fluid flow, indicating the relative importance of convection and conduction.
Symbol: Pr
Measurement: NAUnit: Unitless
Note: Value should be greater than 0.

Other Formulas to find Length

​Go Hydrodynamic entry length
L=0.04DhdReD

Other formulas in Laminar Flow category

​Go Darcy friction factor
df=64ReD
​Go Reynolds Number given Darcy Friction Factor
ReD=64df
​Go Diameter of hydrodynamic entry tube
Dhd=L0.04ReD
​Go Diameter of thermal entry tube
Dt=L0.04ReDPr

How to Evaluate Thermal entry length?

Thermal entry length evaluator uses Length = 0.04*Reynolds Number Dia*Diameter of Thermal Entry Tube*Prandtl Number to evaluate the Length, Thermal entry length formula is defined as a measure of the distance required for a fluid to reach thermal equilibrium within a tube, influencing heat transfer efficiency in laminar flow conditions. Length is denoted by L symbol.

How to evaluate Thermal entry length using this online evaluator? To use this online evaluator for Thermal entry length, enter Reynolds Number Dia (ReD), Diameter of Thermal Entry Tube (Dt) & Prandtl Number (Pr) and hit the calculate button.

FAQs on Thermal entry length

What is the formula to find Thermal entry length?
The formula of Thermal entry length is expressed as Length = 0.04*Reynolds Number Dia*Diameter of Thermal Entry Tube*Prandtl Number. Here is an example- 448 = 0.04*1600*0.066964*0.7.
How to calculate Thermal entry length?
With Reynolds Number Dia (ReD), Diameter of Thermal Entry Tube (Dt) & Prandtl Number (Pr) we can find Thermal entry length using the formula - Length = 0.04*Reynolds Number Dia*Diameter of Thermal Entry Tube*Prandtl Number.
What are the other ways to Calculate Length?
Here are the different ways to Calculate Length-
  • Length=0.04*Diameter of Hydrodynamic Entry Tube*Reynolds Number DiaOpenImg
Can the Thermal entry length be negative?
No, the Thermal entry length, measured in Length cannot be negative.
Which unit is used to measure Thermal entry length?
Thermal entry length is usually measured using the Meter[m] for Length. Millimeter[m], Kilometer[m], Decimeter[m] are the few other units in which Thermal entry length can be measured.
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