Multi-objective optimization and integration of double effect absorption refrigeration system (DEARS) into Kamojang power plant (PP) to improve plant performance

Compared with the single effect, the double effect absorption refrigeration system can take advantage of the higher availability (exergy) of high-temperature heat sources to achieve the higher coefficient of performance (COP). This study proposed DEARS as integrated cooling system improve power plant performance. The heat used for ARS heat demand comes from abandoned well. Absorption will be employed to produce a lower temperature of cooling water from the cooling tower and then pass it on the power plant's condenser. A combined exergy and economic analysis of the modeled system is conducted to calculate exergy efficiency and total annual cost of the system. By linking MATLAB with EES properties database, a multi-objective optimization model is formulated using the genetic algorithm to maximize the first objective and minimize the second objective. The temperature of generator, absorber, condenser, evaporator, temperature delta of cooling water of absorption system and throttle valve pressure of power plant are used as decision variables. The results show that the by integration of DEARS, cooling water temperature reduced up to 20°C from 26°C which give an additional power output of 1.5MW. From the optimization, results show that exergy efficiency increases with total annual cost. Finally, the optimum value for each decision variables areare obtained, which is P-throttle valve = 824.38 kPa, dt-cooling water = 3.12°C, T-evaporator = 7.6°C, T-desorber = 120.08°C, T-condenser = 44.9°C, T-absorber = 33.79°C.