A combined power cycle using refuse incineration and LNG cold energy

The objectives of this paper are to develop a combined power generation cycle using refuse incineration and LNG cold energy, and to conduct parametric analysis to investigate the effects of key parameters on the thermal and exergy efficiencies. The combined cycle consists of an ammonia-water Rankine cycle with refuse incinerator and a LNG cold energy cycle. The combined cycle is compared with the conventional steam Rankine cycle. It was found that the thermal and the exergy efficiencies of the combined cycle were 1.53 and 1.43 times higher than those of the conventional cycle, respectively. The ammonia condensing temperature, turbine inlet and outlet pressures and overall conductance (UA) of the condenser are considered as the key parameters. The thermal and the exergy efficiencies increase with increasing the turbine inlet pressure. As the turbine outlet pressure increases, the thermal efficiency of the combined cycle decreases while the exergy efficiency increases. The present model can be applied to obtain optimum conditions of the key parameters for performance improvement of the combined cycle.C_p specific heat (kJ/kgK)E exergy (kJ/kg)H enthalpy (kJ/kg)HX heat exchangerLHV lower heating value (kJ/kg)LMTD log mean temperature differenceṁ mass flow rate (kg/s)P pressure (kPa)Q heat transfer rate (kW)T temperature (K)UA overall heat conductance (kW/K)W work (kW)η efficiencySubscriptsA airCG city gasex exergyG garbageINC incineratorL LNG cycleN NH₃/H₂O cycleTN1 turbine 1TN2 turbine 2P1 pump 1P2 pump 2O reference (ambient)