**DuctRoundFriction_CL**

Returns the pressure drop associated with a length of round duct given the fluid, its flow rate and state, the diameter and length of the duct. This function calls the PipeFlow function from the heat transfer library assuming a smooth wall.

DELTAP = **DuctRoundFriction_CL**(F$, m_dot, T, P, D, L)

**Inputs:**

F$: fluid string identifier

m_dot: mass flow rate (kg/s, lbm/hr)

T: inlet temperature (K, C, F, or R)

P: inlet pressure (bar, atm, Pa, kPa, or MPa)

D: duct diameter (m or ft)

L: duct length (m or ft)

**Output:**

DELTAP: pressure drop (bar, atm, Pa kPa, or MPa)

**Example: **

$UnitSystem SI Mass J C Pa

$Load Component Library

$VarInfo DP units=Pa

F$ = 'Air'

m_dot = 0.1 [kg/s]

T = 20 [C]

P = 100000 [Pa]

D = 0.1 [m]

L = 5 [m]

DP = **DuctRoundFriction_CL**(F$, m_dot, T, P, D, L)

{**Solution:**

DP = 70.52 [Pa]}