| Summary: | This thesis research aims to develop an improved, efficient, low-capacity heat engine, running
on an Organic Rankine Cycle (ORC) to generate power. The ORC is driven by low or
moderate temperature heat sources, such as; renewable energy in the form of a hot gas derived
from biomass/biogas/biofuel combustion streams, waste heat recovery, process heat recovery,
etc. The ORC is more suitable and flexible than a conventional steam Rankine cycle,
especially when it is applied to low power range. In this research, an extended surface heat
exchanger is used to boil the pressurised working fluid, R134a, using a hot air as heat source.
The expander used is a scroll type, coupled to a generator, which is able to produce maximum
1.6 kW output. Experimental data of the heat engine are measured under different operating
conditions and utilized in the analysis and comparisons. Power generation under various
conditions is investigated in order to determine the optimum performance parameters for the
heat engine.
The isentropic efficiency of the expander is found to be over 40% and reaches 80% for
the improved expansion conditions. For the boiler, it is determined that the overall heat
transfer coefficient multiplied with the heat transfer area is around 150 W/K. The energy
efficiency of the experimental ORC is around 3% for hot air as the low temperature heat
source at about 105oC where exergy efficiency reaches 22%, respectively. === UOIT
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