Performance of Pneumatic Capsule Pipeline Freight Transport System Driven by Linear Motor1

There is growing concern over the problems associated with excessive use of trucks to transport freight. Such problems include air and noise pollution, damage to road surfaces, excessive fuel consumption, traffic congestion, and accidents. Underground capsule freight pipelines promise to alleviate and solve these problems. This paper examines the steady-state performance of a pneumatic capsule pipeline (PCP) freight transport system based on the use of a nonintrusive linear electric motor (LEM) to propel the capsules. A PCP system consisting of a single LEM and a section of pipeline is described, and the equations that relate the various system variables are used in a MATLAB program to conduct a parametric performance study. The results suggest ways to optimize system performance without excessively increasing costs. For example, system mechanical efficiency greater than 90.0% can be obtained with a normalized motor length of the order of 2.0% if the pipe line fill rate is at least 20.0%, the pipe capsule speed is at least $15.0\mathrm{m}∕\mathrm{s}$ , the capsule length-to-diameter ratio is at most $2.0\mathrm{m}∕\mathrm{m}$ , the capsule mass per unit length is at most $250.0\mathrm{kg}∕\mathrm{m}$ , and the end disk to motor-diameter ratio is at least 0.99. When these conditions are satisfied, the thrust per capsule required of the motor and the capsule speed in the motor are relatively insensitive to slight changes in motor length, pipe line fill rate, pipe capsule speed, capsule length or mass, or the drag coefficient in the pipe, results that should simplify the design of the motor.