Question

Twenty pounds per minute of Refrigerant 12 is compressed from 100 psig to 220 psig at a constant temperature of 750oF in a steady flow device.

a/ Determine the amount of work required to compress the gas. Atmospheric pressure = 14.6 psia.

P ⋅ V = constantft⋅lbf T

Rfreon =12.8lbm⋅°R Recall that P⋅V = n⋅R⋅T = m⋅R⋅TR = 8.31 J ;

mol⋅K

4 b/ If the compressor is 94% efficient, what would it cost to run the compressor around the clock for 365 days if electricity costs $0.13/kWh? What would be the annual savings to replace the compressor with a 98% efficient unit?

Answer 1

GIVEN DATA

REFRIGERANT =12

P1=100

P2 =200