Mass Flow Rate

The mass flow rate (m˙ ) of a system is a measure of the mass of fluid passing a point in the system per unit time. The mass flow rate is related to the volumetric flow rate as shown in Equation 3-2 where r is the density of the fluid.

If the volumetric flow rate is in cubic feet per second and the density is in pounds-mass per cubic foot, Equation 3-2 results in mass flow rate measured in pounds-mass per second. Other common units for measurement of mass flow rate include kilograms per second and pounds-mass per hour.

Replacing in Equation 3-2 with the appropriate terms from Equation 3-1 allows the direct ˙V calculation of the mass flow rate.

Example:

The water in the pipe of the previous example had a density of 62.44 lbm/ft3. Calculate the mass flow rate.

Solution: