Superstructures optimization of absorption chiller for WHR of ICE aiming power plant repowering and air conditioning

The present work aims to achieve the optimal solutions in synthesis and design levels for absorption chillers involving waste heat recovery (WHR) with repowering and cooling applications on reciprocating Wärtsilä diesel internal combustion engine (ICE) of 9 MW. The methodology is based on superstructure optimization approach, allowing to define the best configuration and finest parametric variables. This work presents separately three independent superstructures; single-effect powered by hot water or exhaust gases and double-effect powered by exhaust gases. In particular, absorption chillers can provide a chilled water system whose applications on Viana thermoelectric power plant might be performed through the installation of heat exchangers on radiator’s downstream, air conditioning systems and on the intake air of the engine. Therefore, allowing a reduction on electrical energy demand, brake specific fuel consumption and levering the brake shaft power output. A comparison is carried out between the three optimal configurations in terms of thermoeconomic parameters. The best optimal solution in means of highest profit is the hot water single-effect absorption chiller with solution heat exchanger in its structure. For instance, the profit of this optimal solution is US$ 4.75 per hour, which presents a total cost of investment of US$ 588,252.00 and a chilled water specific unit cost of US$ 2523.00 per ton. The benefit is calculated by using International Organization for Standardization documents which gives an amount of additional power output of 45.142 kW (0.517 % ) with a reduction on brake specific fuel consumption around 1.282 g kWh −1 (0.646 % ). The absorption chiller also reduces energy demand at radiator, resulting in 39.719 kW of savings.