Cogeneration and trigeneration systems have been broadly employed as part of
the strategies oriented toward rational energy use. The assessment of these
systems must include simultaneous considerations of costs, irreversibility,
energy losses, and their causes. This work presents a step-by-step
thermoeconomic analysis of a microcogeneration unit, composed of an internal
combustion engine and an ammonia-water single-effect absorption
refrigeration chiller. The research employed the Theory of Exergetic Cost
method to determine monetary and energy costs and the exergy efficiency of
equipment. It is therefore possible to identify which pieces of equipment
present the highest impact and focus on these to improve the overall
performance of the energy system. Although not part of the Theory of
Exergetic Cost, exergoeconomic parameters can be calculated to expand the
assessment further. The highest specific exergy cost is associated with the
endothermic reaction inside the absorber (282 $/GJ), while the lowest
specific exergy cost is due to electricity consumed by the pump of the
refrigeration system (2.16 $/GJ). The highest exergy efficiency was
identified at the condenser (almost 90%, while values under 40% were
obtained for the engine, pump, and absorber. The combined analysis of
exergoeconomic results indicates that the lowest performances are related to
the generator, the absorber, the evaporator, and the regenerator.