Home >> Science & Nature >> Science

How to Calculate Turbo Expander Performance

A turbo expander utilizes a high-pressure gas stream that expands into a centrifugal vane housing to rotate a shaft on a compressor. The heat energy in the high-pressure gas is converted into mechanical energy and cools the exiting gas dramatically. This conversion of energy is highly efficient and relies on the high-pressure gas composition, gas flow rate, gas inlet pressure and gas inlet temperature.

Things You'll Need

Pen
Paper
Calculator

Instructions

- 1
  Determine the flow rate and conditions of the inlet gas. This should be approximately 100,000 pounds of air per hour, at 150 pounds per square inch of pressure. The temperature should be 200 degrees Fahrenheit. At these conditions, the ideal change in energy would be 55 BTU/pound.
- 2
  Determine the expansion change in energy after the gas passes through the expanding vanes. The subsequent horsepower produced by the shaft on the compressor usually determines this. Assume this value is 38 BTU/pound.
- 3
  Determine the turbo expander performance by dividing the actual change in energy by the ideal change in energy. This is 38/55 (x 100) or 69 percent.

Science