In contrast to conventional steam power plants, which employ high-pressure closed cycles, this study presents energy and exergy analyses of a non-conventional lab-scale steam power plant across different boiler pressures, with an emphasis on the effect of cycle openness. Energy loss
from the condenser, turbine work, and thermal efficiency of the cycle have been investigated at different boiler pressures, using energy analysis. Exergy analysis is performed at varying boiler pressures to examine the exergy destruction in the boiler and the condenser, and to evaluate the
cycle’s exergetic efficiency. Experimental results show that minimizing exergy loss in one component of the cycle by varying the boiler pressure may increase it in another component; therefore, an optimal boiler pressure was investigated. As boiler pressure increases, turbine work and efficiencies initially increase because of higher exergy input but subsequently decrease as exergy destruction rises. The optimum boiler pressure is around 2.6 bar, as it minimizes exergy destruction in the cycle and energy loss in the condenser. Because the exergy input is less than the
corresponding heat input, the energy efficiency (5-6.5 %) is found to be lower than the exergetic efficiency (15-21 %). In contrast to previous literature on conventional closed-cycle power plants, the current study finds condenser exergy destruction (542-564 kJ/kg) higher than that of
the boiler (20-98 kJ/kg); this is due to the lack of condensate recirculation and consequent exergy loss at the condenser’s open end.