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Calculation Coil Pressure Drop

Calculation Coil Pressure Drop

Calculation Coil Pressure Drop

(OP)
Trying to balance some hydronic coils.  I have the design gpm, actual gpm and design water pressure drop.  Is there a formula to calculate the actual pressure drop?

RE: Calculation Coil Pressure Drop

generally for a fixed system:

dp(q1)/dp(q2)=(Q1/Q2)^2

that is: pressure drop is proportinal to the flow rate (actually its velocity) squared

Best regrads

Morten

RE: Calculation Coil Pressure Drop

I have fonud this in a forum:

f(coil) = f (straight pipe) *[1+3.5×(d/D)]

f = Moody friction factor
d =inside diameter of the coil tubing
D= Diameter of the helical coil

Reference: Matthew J.Realff & Jde T sommerfield
Georgia insitute of technology)

In addition, if flow is laminar, dp(q1)/dp(q2)=(Q1/Q2)

"We don't believe things because they are true, things are true because we believe them."

RE: Calculation Coil Pressure Drop


Data for friction factors in coils depend on their geometry, e.g. helices, flat or cylindrical spirals, turbulent and laminar conditions, newtonian and non-newtonian fluids.

I found another formula for helices:

ƒ = 0.076 Re-1/4 + 0.0073(d/D)1/2   ± 10%
valid when:
0.34<Re(d/D)2<300

The friction factor, ƒ, can be used to estimate friction drop, Δpf, using:

Δpf ≈ 4 ƒ ρ (L/d) v2/2

Where:

d and D as above; ρ = density; v = velocity.

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