Performance Evaluation of a Combined Heat and Power System with Stirling Engine for Residential Applications
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RESEARCH PAPER
Performance Evaluation of a Combined Heat and Power System with Stirling Engine for Residential Applications Mohammad Sheykhi1 · Mahmood Chahartaghi1 · Seyed Majid Hashemian1 Received: 31 January 2018 / Accepted: 2 July 2019 © Shiraz University 2019
Abstract A combined heating and power (CHP) system with a Stirling engine for building applications has been proposed in the present work. The use of these systems in building applications will be more common if they have significant advantages from the viewpoints of the pollution emission and operational cost in comparison with the other similar systems. The Stirling engine was modeled with consideration of different losses of its components. In addition, the effect of Stirling engine speed on efficiency, carbon dioxide emission, annual tax on carbon dioxide emissions and operational cost was analyzed. The results showed that the CHP system at low rotational speeds had better performance than other rotational speeds. Furthermore, the CHP system could achieve 900 $ reduction in annual costs of CO2 tax compared to the conventional system during operation. Keywords CHP · Stirling engine · Non-ideal adiabatic · Rotational speed List of Symbols General A Cross-sectional area (m2) Acond Conductive area (m2) a Coefficient for finite speed thermodynamic (−) CO2T Carbon dioxide tax ($) CR Operational cost reduction (−) c Average speed of molecules (m s−1) cp Specific heat at constant pressure (Jkg−1 K−1) cv Specific heat at constant volume (Jkg−1 K−1) D Hydraulic diameter (m) dd Diameter of displacer (m) f Friction factor fr Rotation frequency of engine (HZ) G Working gas mass flow h Convective heat transfer coefficient of gas J Gap between displacer and cylinder (m) kg Thermal conductivity of working gas (W m−1 K−1) kr Thermal conductivity of regenerator wall (W m−1 K−1) Ld Displacer length (m) * Mahmood Chahartaghi [email protected] 1
Faculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran
Lr Regenerator length (m) M Mass of the working fluid (kg) NTU Number of the transfer units (−) nr Engine rotational speed (rpm) P Power output (W) Pr Prandtl number (−) p Pressure (Pa) Q Heat transfer (W) R Gas constant (J kg−1 K−1) Re Reynolds number (−) S Displacer stroke (m) St Staunton number T Temperature (K) CO2ER CO2 emission reduction (−) V Volume (m3) W Work output (J) w Piston velocity (m s−1) Greek θ Crank angle (deg) μ Dynamic viscosity (kg m−1 s−1) ɛ Effectiveness (−) η Efficiency (−) γ Specific heat ratio (cp · c−1 v ) (−) Subscript ac Actual adi Ideal adiabatic c Compression space
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Vol.:(0123456789)
Iranian Journal of Science and Technology, Transactions of Mechanical Engineering
ck Cooler–compression space interface e Expansion space gen Generator gh Inside of heater gk Inside of cooler h Heater he Heater–expansion space interface k Cooler kr Cooler–regenerator interface r Regenerator rh Regenerator–heater interface sh Shuttle effect wh H
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