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Properties of Working Fluids
Published in Reinhard Radermacher, Yunho Hwang, Vapor Compression Heat Pumps, 2005
Reinhard Radermacher, Yunho Hwang
The azeotropic point changes its mass fraction with the saturation pressure level and can disappear altogether for certain conditions. A zeotropic mixture may have an azeotropic point at other conditions and vice versa.
Thermodynamic and multi-objective optimisation of solar-driven Organic Rankine Cycle using zeotropic mixtures
Published in International Journal of Ambient Energy, 2019
Deepak Tiwari, Ahmad Faizan Sherwani, Akhilesh Arora
Tchache et al. (2009) compared the theoretical performance, thermodynamic and environmental properties of fluids for the use in ORC systems operated by low-temperature solar energy. The investigation showed that R134a is the best fluid for small-scale solar power generation in comparison to R152a and R600a. Wang, Zhao, and Wang (2010) developed an ORC-based prototype model, utilising R245fa, with the flat plate solar collector and evacuated solar collector as a low-temperature energy source and a rolling type piston expander for producing power. The efficiency of overall power generation was observed to be 4.2% with the evacuated solar collector and 3.2% for the flat plate collector. Wang et al. (2010) analysed a low-grade solar powered ORC considering pure fluid R245fa and a zeotropic mixture of R245fa/R152a (0.9/0.1, 0.7/0.3). It was reported that overall efficiency can be improved by using zeotropic mixture as compared with pure fluids.
Optimization and thermo-economic performance analysis of organic Rankine cycles using mixture working fluids driven by solar energy
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Deepak Tiwari, Ahmad Faizan Sherwani, Nishant Kumar
The issue while using zeotropic mixture is the lower value of heat transfer coefficient which results in higher heat exchanger area leading to more cost than pure working. The composition shift phenomenon of the zeotropic mixture during phase change occurs due to the difference in composition of the charged mixture, and circulating mixture results in lower network output of the ORC system. Furthermore, the existence of wider temperature glide of >15 K results in the phenomena of fractionating of zeotropic mixture.