Assessment of Working Fluid Mixtures for Solar Organic Rankine Cycles

Abstract

This work investigates the performance of binary working fluid mixtures in a low temperature solar Organic Rankine Cycle (ORC) system including heat storage. Conventional mixtures widely considered in published literature are compared with optimum mixtures previously obtained using a computer-aided molecular design method in Papadopoulos et al. (2013). The system performance is investigated for a real solar radiation profile for an entire year of operation. Inclusive, steady-state mathematical models are used for the simulation of both the solar collectors and the ORC. The effects of different mixtures on several important system operating parameters are investigated. Results indicate that mixtures at different compositions and concentrations may have a significantly different performance in terms of parameters such as generated work, required collector aperture area and so forth. Neopentane- based mixtures appear as promising candidates of high overall performance for solar ORCs.