Optimization of cyclic parameters for ORC system using response surface methodology (RSM)

ABSTRACT

The present work focuses on response surface methodology-backed thermodynamic analysis of organic Rankine cycle (ORC) driven by low-temperature heat sources (temperatures less than 150°C). The zeotropic mixture of Butane and Pentane is employed as a working fluid. Both pure fluids have zero ozone depletion potential and lower global warming potential. The second order nonlinear polynomial mathematical model was developed by RSM methodology to get the relationship between thermal efficiency of ORC and decision variables. Furthermore, the analysis of variance (ANOVA) technique was applied to get apprehend of most significant decision variables in terms of p-values and F-values. In addition, contour plots were drawn to analyze a range of decision variables in which thermal efficiency of ORC is found to be higher. The results indicate that the thermal efficiency is mostly affected by heat sink temperature, followed by isentropic efficiency of the turbine and mass fraction of zeotropic mixture.

KEYWORDS:

• ORC
• low-temperature heat source
• zeotropic mixture
• RSM and internal heat exchanger

Nomenclature

$Q_e$	=	ORC evaporator heat input (KW)
${\eta }_p$	=	Isentropic efficiency of pump
${\eta }_t$	=	Isentropic efficiency of turbine
$W_p$	=	Pump Work (KW)
$W_t$	=	Turbine work (KW)
${m^{.}}_{orc}$	=	Mass flux of working fluid in ORC (kgs−1)
Qc	=	Cooling load on condenser (KW)
${\epsilon }_{ihe}$	=	Effectiveness of heat exchanger
MF	=	Mass fraction of zeotropic mixtures
${\eta }_{orc}$	=	Thermal efficiency of ORC

Abbreviation

ORC	=	Organic Rankine cycle
OA	=	Orthogonal Array
GWP	=	Global warming potential
ODP	=	Ozone depletion potential
ANOVA	=	Analysis of Variance
RSM	=	Response surface methodology

Additional information

Notes on contributors

Ashwni Goyal

Ashwni Goyal working as Assistant Professor in Mechanical and Automation Engineering Department of Maharaja Agrasen Institute of Technology, Delhi, India.His Research area includes low- grade heat source power generation.

Ahmad Faizan Sherwani

Ahmad Faizan Sherwani is working as an Associate Professor in Department of Mechanical Engineering of Jamia Millia Islamia University, Delhi. His research area includes Solar Energy, alternate refrigeration technologies, exergy analysis of thermal systems and renewable, sustainable energy and life cycle analysis. He has published  plenty of research paper in reputed  international  and national journals. He has worked as reviewer in several reputed general.

Deepak Tiwari

Deepak Tiwari working as Assistant Professor in Mechanical Engineering Department of Bhagwan Parshuram Institute of Technology,  Delhi, India. His research area includes low-grade solar thermal power generation.