QUESTION

Text
Image

# A low-humidity clean room receives some of its mechanical energy from a gas turbine. Gas flowing through the turbine is a mixture of carbon dioxide and nitrogen. The following data is available. \begin{tabular}{ll} turbine mechanical efficiency & $85 \%$ \\ turbine isentropic efficiency & $70 \%$ \\ turbine power output & $5.2 \mathrm{bhp}$ \\ gas mixture flow rate & $340 \mathrm{lbm} / \mathrm{hr}$ \\ turbine inlet gas temperature & $240{ }^{\circ} \mathrm{F}$ \\ turbine exit gas pressure & $16 \mathrm{psia}$ \\ gas mixture properties & \\ $\quad \begin{array}{l}\text { specific gas constant } \\ \text { specific heat at } \\ \text { constant pressure }\end{array}$ & $0.057 \mathrm{BTU} / \mathrm{lbm}-{ }^{\circ} \mathrm{R}$ \\ \multicolumn{1}{r}{ ratio of specific heats } & $0.218 \mathrm{BTU} / \mathrm{lbm}-{ }^{\circ} \mathrm{R}$ \\ & 1.355 \end{tabular} (a) What is the turbine inlet pressure? (b) What is the efficiency of the power generation process? (c) What is the entropy change of the gas mixture? (d) Sketch (and label) the $T$-s diagram for the expansion process. A waste heat boiler produces 700 psia (dry, saturated) steam from $220^{\circ} \mathrm{F}$ feedwater. The boiler receives energy from 40,000 lbm/hr of $1750^{\circ} \mathrm{F}$ (dry) air. After passing through the waste heat boiler, the temperature of the air has been reduced to $180^{\circ} \mathrm{F}$ above the steam temperature. (a) How much steam is produced per hour? (b) After expanding through a turbine, $80 \%$ of the condensate (saturated liquid at $190^{\circ} \mathrm{F}$ ) is returned to a deaerator-heater. What quantity of boiler do fast! both  