Combined energetic and exergetic assessment of a biomass-based integrated power and refrigeration plant

Abstract

In this study, an integrated power and refrigeration plant, based on biomass gasification, has been modeled and analyzed. The producer gas generated by gasification of solid biomass undergoes full combustion in a combustor-heat exchanger (CHX) and heats up compressed air for an indirectly heated gas turbine (GT) cycle. The waste heat of the CHX exhaust is further recovered in a recovery boiler to produce steam for the generator of an absorption refrigeration (VAR) unit. Energetic and exergetic assessments have been performed for this integrated plant. Major plant parameters, viz. GT cycle pressure ratio and turbine inlet temperature were varied to find optimized plant configuration. The results show that at a GT cycle pressure ratio 10, the plant yields highest electrical efficiency of 27% when the GT inlet air temperature is 1100 °C. At this point, the plant has the lowest cooling-to–power ratio (CTPR, value being 1.18), although this point also gives best exergetic performance; with a combined exergetic efficiency of 27.6%. The plant also gives lowest exergetic specific biomass consumption of 0.7 kg/kWh and highest fuel energy savings ratio of about 45% at the same point.