Thermal matching performance of a geothermal ORC system using zeotropic working fluids

The thermal matching performance analysis is conducted for a geothermal organic Rankine cycle system using zeotropic mixtures as working fluids. The constant isentropic efficiency is replaced by internal efficiency of an axial flow turbine with given size for each condition, and the zeotropic mixtures of isobutane and isopentane is used as working fluids of the organic Rankine cycle, in order to improve thermal match in evaporator and condenser. The results showed the use of zeotropic mixtures leads to the prominent thermodynamic first law and second law efficiencies, especially at high minimum temperature difference in evaporator (Δt1), and there exists an optimal thermal performance at some certain mole fraction of isopentane in zeotropic mixtures (x) and Δt1. The geothermal organic Rankine cycle with x of 0.2 and Δt1 of 16 K shows the maximal thermodynamic first law and second law efficiency in this research. The geothermal organic Rankine cycle system using zeotropic mixtures shows the optimal overall thermal performance at some certain x, which is not necessary to be the point with the maximal temperature glide. The use of zeotropic mixtures is not always lead to a high thermal to electricity efficiency compared to the pure working fluid, and its overall net power output of PORC is even lower than the pure working fluids compositions at some certain x.

[1]  Bertrand F. Tchanche,et al.  Fluid selection for a low-temperature solar organic Rankine cycle , 2009 .

[2]  Hao Liu,et al.  Performance analysis of regenerative organic Rankine cycle (RORC) using the pure working fluid and the zeotropic mixture over the whole operating range of a diesel engine , 2014 .

[3]  Julián Blanco,et al.  Performance of a 5kWe Organic Rankine Cycle at part-load operation , 2014 .

[4]  Li Zhao,et al.  The influence of composition shift on organic Rankine cycle (ORC) with zeotropic mixtures , 2014 .

[5]  Stefano Clemente,et al.  Experimental tests and modelization of a domestic-scale ORC (Organic Rankine Cycle) , 2013 .

[6]  Ibrahim Dincer,et al.  Thermodynamic analysis of a novel ammonia-water trilateral Rankine cycle , 2008 .

[7]  Vincent Lemort,et al.  Testing and modeling a scroll expander integrated into an Organic Rankine Cycle , 2009 .

[8]  N. Lai,et al.  Working fluids for high-temperature organic Rankine cycles , 2007 .

[9]  Huijuan Chen,et al.  Energetic and exergetic analysis of CO2- and R32-based transcritical Rankine cycles for low-grade heat conversion , 2011 .

[10]  Daniele Fiaschi,et al.  Thermo-fluid dynamics preliminary design of turbo-expanders for ORC cycles , 2012 .

[11]  Vincent Lemort,et al.  Experimental study and modeling of an Organic Rankine Cycle using scroll expander , 2010 .

[12]  Tao Guo,et al.  Comparative analysis of CO2-based transcritical Rankine cycle and HFC245fa-based subcritical organic Rankine cycle using low-temperature geothermal source , 2010 .

[13]  Johann Fischer,et al.  Comparison of trilateral cycles and organic Rankine cycles , 2011 .

[14]  Lisheng Pan,et al.  Improved analysis of Organic Rankine Cycle based on radial flow turbine , 2013 .

[15]  Jin-Kuk Kim,et al.  Composition optimisation of working fluids for Organic Rankine Cycles and Kalina cycles , 2013 .

[16]  Jie Ji,et al.  Construction and dynamic test of a small-scale organic rankine cycle , 2011 .

[17]  Per Lundqvist,et al.  A comparative study of the carbon dioxide transcritical power cycle compared with an organic rankine cycle with R123 as working fluid in waste heat recovery , 2006 .

[18]  Hong Guang Zhang,et al.  Performance analysis of a novel system combining a dual loop organic Rankine cycle (ORC) with a gasoline engine , 2012 .

[19]  G. Shu,et al.  Theoretical research on working fluid selection for a high-temperature regenerative transcritical dual-loop engine organic Rankine cycle , 2014 .

[20]  Michele Bianchi,et al.  Bottoming cycles for electric energy generation: Parametric investigation of available and innovative solutions for the exploitation of low and medium temperature heat sources , 2011 .

[21]  Markus Preißinger,et al.  Zeotropic mixtures as working fluids in Organic Rankine Cycles for low-enthalpy geothermal resources , 2012 .