Abstract
In this publication, we present an energy and exergy analysis of the Szewalski binary vapor cycle based on a model of a supercritical steam power plant. We used energy analysis to conduct a preliminary optimization of the cycle. Exergy loss analysis was employed to perform a comparison of heat-transfer processes, which are essential for hierarchical cycles. The Szewalski binary vapor cycle consists of a steam cycle bottomed with an organic Rankine cycle installation. This coupling has a negative influence on the thermal efficiency of the cycle. However, the primary aim of this modification is to reduce the size of the power unit by decreasing the low-pressure steam turbine cylinder and the steam condenser. The reduction of the “cold end” of the turbine is desirable from economic and technical standpoints. We present the Szewalski binary vapor cycle in addition to a mathematical model of the chosen power plant’s thermodynamic cycle. We elaborate on the procedure of the Szewalski cycle design and its optimization in order to attain an optimal size reduction of the power unit and limit exergy loss.
Highlights
In the 1960s, Robert Szewalski introduced a binary vapor cycle consisting of a supercritical steam cycle and an organic Rankine cycle (ORC) coupled in a hierarchical energy system
Our analysis has revealed that the Szewalski binary vapor cycle has a great potential in the field of reducing the size of power units
The binary cycle is associated with some energy losses and a slight decrease in energy efficiency relative to a single steam cycle
Summary
In the 1960s, Robert Szewalski introduced a binary vapor cycle consisting of a supercritical steam cycle and an organic Rankine cycle (ORC) coupled in a hierarchical energy system. The application of low-boiling point fluids in energy cycles is associated with advantages other than the utilization of low-temperature heat sources [11] One of these advantages is employed in the Szewalski binary vapor cycle. In the second part of the cycle, the ORC provides a working fluid with a low specific volume The objective of this concept is to significantly reduce the LP turbine sizes and make it possible to increase the output power attainable by a single turbine unit [1,2]. In the Szewalski binary vapor cycle, we considered four potential working fluids (propane, isobutene, ethanol and ammonia) to obtain the highest output and a First Law efficiency of the cycle Another supercritical steam cycle that utilizes an ORC cycle has been analyzed in the literature [13,14].
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