Study of Methods to Enhance Energy Utilization Efficiency of Micro Combined Heat and Power Generation Unit-Equipped with an Extended Expansion Linkage Engine and Reduction of Waste Energy 2011-32-0574
To increase energy utilization efficiency of a micro combined
heat and power generation unit, methods for simultaneously
enhancing efficiencies of power generation and of heat recovery,
which are normally in the trade-off relationship has been
studied.
To increase power generation efficiency, an extended expansion
linkage engine higher in thermal efficiency than conventional
engines has been adopted. The power generation efficiency was
enhanced by 3.8 points to 26.3% from 22.5% of a conventional
model.
However, since introducing an extended expansion engine
increases kinetic energy and lowers the temperature of exhaust gas
from the engine, it is difficult to enhance the heat recovery.
Focusing on the fact that most released heat energy is discharged
through ventilation from the unit, ventilation cooling system was
reexamined, and reduction of the released heat energy was
considered.
First, positioning of heat-generative electronic parts on the
inverter was changed, and the minimum airflow necessary for cooling
was determined. In order to cool the entire unit with this airflow,
an effective way to cool the alternator and the engine room was
examined, and a method in which the ventilation which previously
cooled the alternator is then delivered into the engine room was
adopted.
Consequently, it became possible to reduce the airflow rate from
35 m₃/h in a conventional model to 13 m₃/h, and the heat recovery
efficiency was enhanced by 2.7 points to 65.7%. The simultaneous
enhancement in efficiencies of power generation and heat recovery
was realized, and energy utilization efficiency reached 92%, a 6.5
point increase from 85.5% (the efficiency is based on the lower
heating value).
