Comparing the thermodynamic performance of organic rankine and kalina cycles in solar energy systems

Abstract

This paper reports on a comparative study of the thermodynamic performance of the organic Rankine cycle (ORC) and Kalina cycle 11 (KCS11) using solar energy for application in residential or commercial sectors. The objective was to determine the amount of power that can be produced by solar energy systems using low-quality energy sources (hot water at temperatures above 60 oC), from the viewpoints of the first and second laws of thermodynamics. Moreover, the performance impact of coupling these cycles to hybrid solar photovoltaic-thermal collector systems (PV/T) to increase the total power generation for the same surface area was analyzed. In particular, the PV/T systems were employed to increase the production of solar energy systems, as the efficiency of photovoltaic cells reduces under hot climates, such as the climate in Brazil. The results indicated that the exergy efficiency of the KCS11 is higher than that for the ORC. Nevertheless, both cycles as the bottoming cycles to PV/T collector configurations increased the total theoretical electric power generation, for the design study, in approximately 0.4 kW per unit of area