Hot combustion gases, modeled as air behaving as an ideal gas, enter a steady-state turbine at 145 psi, 2700oR, and exit at 29 psi and 1974oR. The power output is 74.26 hp, and heat transfer from the turbine to the surroundings occurs at a rate of 14 BTU/s.
Required:
a)Determine the power output of the turbine, in hp.
b) The Flow rate
Answer:
a) [tex]w=74.26hp[/tex]
b) [tex]m=0.22[/tex]
Explanation:
From the question we are told that:
Initial Pressure [tex]p_1= 145 psi[/tex]
Initial Temperature [tex]T_1 =2700oR=>2240.33^oF[/tex]
Final Pressure [tex]p_2= 29 psi[/tex]
Final Temperature [tex]t_2=1974oR=>1514.33^oF[/tex]
Output Power [tex]w=74.26hp[/tex]
Heat transfer Rate [tex]Q=14BTU/s[/tex]
Generally the equation for Steady flow energy is mathematically given by
[tex]Q-w=m(h_2-h_1)[/tex]
Where
[tex]m=Flow\ rate[/tex]
From Steam table
[tex]h_1=704btu/ib (at\ p_1= 145\ psi,\ T_1 =2700oR=>2240.33^oF )[/tex]
[tex]h_2=401btu/ib (at\ p_2= 29psi\ t_2=1974oR=>1514.33^oF )[/tex]
Therefore
[tex]-14-74.26=m(401-704)[/tex]
[tex]m=\frac{-14-74.26}{(401-704)}[/tex]
[tex]m=0.22[/tex]
