Experimental analysis of a micro-ORC driven by piston expander for low-grade heat recovery

Abstract In this paper, a full experimental characterization of a micro-scale ORC system is presented. The facility under investigation is driven by a piston expander prototype, made of three cylinders arranged radially around the drive shaft. The system is rated for a thermal input around 30 kW, being suitable for residential, tertiary sector or small industry applications. It is conceived for exploiting low temperature heat sources, such as solar collectors, biomass boilers, geothermal energy or waste heat streams. The facility was provided with an electric boiler as heat source, which warms water up to 90 °C, and cold water at ambient temperature as heat sink. A test campaign was performed varying the hot source temperature and the organic fluid feed pump velocity, in order to characterize the system behavior at different off-design working conditions. The electric consumption of the ORC feed pump was measured, in order to quantify the actual impact of the auxiliaries on the overall efficiency. Moreover, the number of electric loads connected to the generator was varied, changing the equivalent phase impedance value, for evaluating the effect on the expander rotating speed and power output. The experimental analysis demonstrated that small reciprocating expander is suitable for exploiting low enthalpy heat sources, with quite good performances compared to other architectures like scroll and screw expanders, more applied within low temperature sources. The results show that the gross electric power output varied between 250 W and 1150 W, depending on the expander speed and on the number of electric loads activated. The expander total efficiency showed a barely constant trend around 40%. The pump total efficiency varied between 10% and 20%, increasing with the pump rotational speed. The maximum ORC gross and net efficiency were 4.5% and 2.2% respectively, confirming that the auxiliaries impact cannot be considered negligible in such type of systems.

[1]  A. Pesyridis,et al.  Review of Organic Rankine Cycle experimental data trends , 2018, Energy Conversion and Management.

[2]  Eckhard A. Groll,et al.  Characterizing the performance of a single-screw expander in a small-scale organic Rankine cycle for waste heat recovery , 2016 .

[3]  R. E. Franklin,et al.  Absolute measurements of static-hole error using flush transducers , 1970, Journal of Fluid Mechanics.

[4]  R. P. Benedict,et al.  Fundamentals of temperature, pressure, and flow measurements , 1977 .

[5]  R. R. Rhinehart,et al.  An efficient method for on-line identification of steady state , 1995 .

[6]  Yi Liu,et al.  Experimental study on free piston linear generator (FPLG) used for waste heat recovery of vehicle engine , 2017 .

[7]  A. Grönman,et al.  Thermodynamic evaluation on the effect of working fluid type and fluids critical properties on design and performance of Organic Rankine Cycles , 2018, Journal of Cleaner Production.

[8]  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 .

[9]  Kyung Chun Kim,et al.  Experimental investigation of an organic Rankine cycle with multiple expanders used in parallel , 2015 .

[10]  Antonio J. Torregrosa,et al.  Dynamic tests and adaptive control of a bottoming organic Rankine cycle of IC engine using swash-plate expander , 2016 .

[11]  Saffa Riffat,et al.  Development of small-scale and micro-scale biomass-fuelled CHP systems – A literature review , 2009 .

[12]  Rémi Revellin,et al.  Organic Rankine cycle design and performance comparison based on experimental database , 2017 .

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

[14]  Assaad Zoughaib,et al.  Experimental investigation and modeling of a hermetic scroll expander , 2016 .

[15]  Vincent Lemort,et al.  Experimental performance of a piston expander in a small- scale organic Rankine cycle , 2015 .

[16]  Vincent Lemort,et al.  Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp , 2014, Industrial & engineering chemistry research.

[17]  Chen Shan Kao,et al.  Detecting changes of steady states using the mathematical theory of evidence , 1987 .

[18]  Xiaorong He,et al.  Application of steady-state detection method based on wavelet transform , 2003, Comput. Chem. Eng..

[19]  Peng Liu,et al.  Preliminary tests on dynamic characteristics of a CO2 transcritical power cycle using an expansion valve in engine waste heat recovery , 2017 .

[20]  R. Russell Rhinehart,et al.  Critical values for a steady-state identifier , 1997 .

[21]  Michele Pinelli,et al.  Experimental Performance of a Micro-ORC Energy System for Low Grade Heat Recovery , 2017 .

[22]  James E. Braun,et al.  Experimental and numerical analyses of a 5 kWe oil-free open-drive scroll expander for small-scale organic Rankine cycle (ORC) applications , 2018, Applied Energy.

[23]  Piotr A. Domanski,et al.  Design of a steady-state detector for fault detection and diagnosis of a residential air conditioner , 2008 .

[24]  Vincent Lemort,et al.  Techno-economic survey of Organic Rankine Cycle (ORC) systems , 2013 .

[25]  Vincent Lemort,et al.  Experimental study on an open-drive scroll expander integrated into an ORC (Organic Rankine Cycle) system with R245fa as working fluid , 2013 .

[26]  Eckhard A. Groll,et al.  Experimental Testing of an Organic Rankine Cycle with Scroll-type Expander , 2012 .

[27]  Noboru Yamada,et al.  Experiment on pumpless Rankine-type cycle with scroll expander , 2013 .

[28]  Anthony Paul Roskilly,et al.  Investigation on a small-scale pumpless Organic Rankine Cycle (ORC) system driven by the low temperature heat source , 2017 .

[29]  Zhaobin Qiu,et al.  Influence of Thermally Reduced Graphene Low-Loadings on the Crystallization Behavior and Morphology of Biodegradable Poly(ethylene succinate) , 2014 .

[30]  Vincent Lemort,et al.  Experimental investigation and optimal performance assessment of four volumetric expanders (scroll, screw, piston and roots) tested in a small-scale organic Rankine cycle system , 2018, Energy.

[31]  Rémi Revellin,et al.  Performance investigation of reciprocating pump running with organic fluid for organic Rankine cycle , 2017 .

[32]  V. Lemorta,et al.  A COMPARISON OF PISTON , SCREW AND SCROLL EXPANDERS FOR SMALL-SCALE RANKINE CYCLE SYSTEMS , 2013 .

[33]  Kyung Chun Kim,et al.  Experimental study of a 1 kw organic Rankine cycle with a zeotropic mixture of R245fa/R134a , 2015 .

[34]  Fubin Yang,et al.  Free piston expander-linear generator used for organic Rankine cycle waste heat recovery system , 2017 .