# Automobile Pump Power

Gasoline is pumped from the gas tank of an automobile to the carburetor through a 10 ft long, 1/4" diameter fuel line of steel tubing. The line has five 90 degree smooth bends with r/d of 6. The gasoline discharges through a 1/32" diameter jet in the carburetor to a pressure of 14 psia. The pressure in the tank is 14.7 psia. If the pump is 80% efficient, what power must be supplied by the pump if the automobile is accelerating and consuming fuel at the rate of 0.1 gal/min.?

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#### Solution Preview

The frictionless flow energy equation states the sum of energies at any point on the flow energy line should be constant.

Therefore

Pressure energy + kinetic energy + potential energy = constant

Pressure energy = static Pressure / density

Kinetic energy = half of Square of velocity

Potential energy = static head x gravitational acceleration

Then applying this to carburetor tube:

Pressure/density + V^2/2 + gZ = constant across any point on the gasoline feed line

Applying the energy equation between points 1 and 2 on the energy line yields:

P1/density1 + 1/2 (V1)^2 + gZ1 = P1/density1 + 1/2 (V1)^2 + gZ1 ----- (1)

If the flow experiences some pipe friction losses and energy added to the flow from the fuel pump the above equation could be written as:

P1/density + 1/2 (V1)^2 + gZ1 = P2/density1+ 1/2 (V2)^2 + gZ2 + pipe friction and secondary energy losses - fuel pump energy ------ ...

#### Solution Summary

The frictionless flow energy equation states the sum of energies at any point on the flow energy line should be constant. This solution provides calculations and is 575 words.