Question

A steam turbine receives steam at 600 psia and 600°F and exhausts it at 1 inch of mercury absolute to a condenser. The turbine develops 400 Btu of work from each pound of steam passing through. Calculate: (a) the ideal work of the turbine (b) the engine efficiency of the turbine.

Answer 1

(a)466.2 btu/lbm (b) 85.8%

Step-by-step explanation:

We have given that turbine receives steam at 600 psi and 600°F

So
`P_1=600psi` and
`T_1=600^(\circ)F`

From the standard steam table at 600 psi and 600°F

`h_1=1289.9btu/lbm\ and s_1=1.5325btu/lbm^(\circ)R`

Assuming the expansion is isotropic in nature so
`s_1=s_2`

At the exhausts
`P_2=1\ inch\ hg=0.491psi`

From the steam table at 0.491 psi and
`s_2=1.5325btu/lbm^(\circ)R`

`h_2=823.7btu/lbm`

(a)So work done
`w=h_1-h_2=1289.9-823.7=466.2btu/lbm`

(b) Efficiency
`\eta =(work\ done)/(w_(ideal))=(400)/(466)=0.858`=85.8%