Page 98 - Handbook of Energy Engineering Calculations
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rate. To compute any of these values, use the equations given and insert the
applicable variables.
ENERGY PERFORMANCE OF REHEAT-STEAM CYCLE
2
A reheat-steam cycle has a 2000 lb/in (abs) (13,790-kPa) throttle pressure at
2
the turbine inlet and a 400-lb/in (abs) (2758-kPa) reheat pressure. The
throttle and reheat temperature of the steam is 1000°F (537.8°C); condenser
pressure is 1 inHg absolute (3.4 kPa); engine efficiency of the high-pressure
and low-pressure turbines is 80 percent. Find the cycle thermal efficiency.
Calculation Procedure:
1. Sketch the cycle layout and cycle T-S diagram
Figures 20 and 21 show the cycle layout and T-S diagram with each
important point numbered. Use a cycle layout and T-S diagram for every
calculation of this type because it reduces the possibility of errors.
FIGURE 20 Typical steam reheat cycle.
2. Determine the throttle-steam properties from the steam tables
2
Use the superheated steam tables, entering at 2000 lb/in (abs) (13,790 kPa)
