The compressed air requirements of a textile factory are met by a large compressor that draws in 0.6 m³/s air at atmospheric conditions of 20°C and 1 bar (100 kPa) and consumes 300 kW electric power when operating. Air is compressed to a gage pressure of 8 bar (absolute pressure of 900 kPa), and compressed air is transported to the production area through a 30-cm-internal-diameter, 83- m-long, galvanized steel pipe with a surface roughness of 0.15 mm. The average temperature of compressed air in the pipe is 60°C. The compressed air line has 8 elbows with a loss coefficient of 0.6 each. If the compressor efficiency is 82 percent, determine the power wasted in the transportation line. The roughness of a galvanized steel pipe is given to be ε = 0.00015 m. The dynamic viscosity of air at 60°C is = 2.008 x 10-5 kg/m-s, and it is independent of pressure. The density of air listed in that table is for 1 atm. The density at 20°C, 100 kPa and 60°C, 900 kPa can be determined from the ideal gas relation to be P Pin RT 100 kPa (0.287 kPa-m³/kg-K)(20+273 K) Pine = 1.189 kg/m³ 900 kPa (0.287 kPa-m³/kg-K)(60+273 K) The power wasted in the transportation line is P= Pline=RTline = 9.417 kg/m³ kW.

The compressed air requirements of a textile factory are met by a large compressor that draws in 0.6 m³/s air at atmospheric conditions of 20°C and 1 bar (100 kPa) and consumes 300 kW electric power when operating. Air is compressed to a gage pressure of 8 bar (absolute pressure of 900 kPa), and compressed air is transported to the production area through a 30-cm-internal-diameter, 83- m-long, galvanized steel pipe with a surface roughness of 0.15 mm. The average temperature of compressed air in the pipe is 60°C. The compressed air line has 8 elbows with a loss coefficient of 0.6 each. If the compressor efficiency is 82 percent, determine the power wasted in the transportation line. The roughness of a galvanized steel pipe is given to be ε = 0.00015 m. The dynamic viscosity of air at 60°C is = 2.008 x 10-5 kg/m-s, and it is independent of pressure. The density of air listed in that table is for 1 atm. The density at 20°C, 100 kPa and 60°C, 900 kPa can be determined from the ideal gas relation to be P Pin RT 100 kPa (0.287 kPa-m³/kg-K)(20+273 K) Pine = 1.189 kg/m³ 900 kPa (0.287 kPa-m³/kg-K)(60+273 K) The power wasted in the transportation line is P= Pline=RTline = 9.417 kg/m³ kW.

Sustainable Energy

2nd Edition

ISBN:9781337551663

Author:DUNLAP, Richard A.

Publisher:DUNLAP, Richard A.

Chapter14: Ocean Thermal Energy Conversion And Ocean Salinity Gradient Energy

Section: Chapter Questions

Problem 9P

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