AKSHAY RAJEEVAN NAMBIAR (STM18ME006)

AMARNATH P (STM18ME007)

GOKUL GANGADHARAN (STM18ME012)

JOYAL TOM BABU (STM18ME014)

Stirling engines with Fresnel lens concentrator for thermal to electric conversion of solar energy is
one of the most promising solutions of renewable energy technologies in order to reduce the
dependency from fossil fuels in electricity generation. This paper addresses the modelling and
fabrication of a solar powered alpha Stirling engine system with parabolic dish and electric generator
aiming to determine its energy production and efficiency. The model includes the solar radiation
concentration system, the heat transfer in the thermal receiver, the thermal cycle and the mechanical
and electric energy conversion. The thermodynamic and energy transfer processes in the engine are
modelled in detail, including all the main processes occurring in the compression, expansion and
regenerator spaces. Starting from a particular configuration, an optimization of the concentration
factor is also carried out and the results for both the transient and steady state regimes are presented. It
was found that using a directly illuminated thermal receiver without cavity the engine efficiency is
close to 23.8% corresponding to a global efficiency of 10.4%. The components to be optimized are
identified in order to increase the global efficiency of the system and the trade-off between system
complexity and efficiency is discussed. A solar-driven Stirling engine is modelled as a combined
system which consists of a solar concentrator and a Stirling engine. The performance of the system is
investigated, based on the linearized heat loss model of the solar collector and the irreversible cycle
model of the Stirling engine affected by finite-rate heat transfer and regenerative losses. The
maximum efficiency of the system and the optimal operating temperature of the solar concentrator are
determined. Moreover, it is pointed out that the investigation method in the present paper is valid for
other heat loss models of the solar concentrator as well, and the results obtained are also valid for a
solar-driven Ericsson engine system using an ideal gas as its engine work substance.