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This work presents a thermoeconomic analysis of a cogeneration system using the exhaust gas from a natural gas-fueled diesel power generator as heat source for an ammonia-water absorption refrigeration system. The purpose of the analysis is to obtain both unit exergetic and exergoeconomic costs of the cogeneration system at different load conditions and replacement rates of diesel oil by natural gas. A thermodynamic model of the absorption chiller was developed using the Engineering Equation Solver (EES) software to simulate the exergetic and exergoeconomic cogeneration costs. The data entry for the simulation model included available experimental data from a dual-fuel diesel power generator operating with replacement rates of diesel oil by natural gas of 25%, 50% and 75%, and varying engine load from 10 kW to 30 kW. Other required data was calculations using the GateCycle software, from the available experimental data. The results show that, in general, the cogeneration cold unit exergetic and exergoeconomic costs increases with increasing engine load and decreases with increasing replacement rate of diesel oil by natural gas under the conditions investigated. Operating with 3/4 of the rated engine power and replacing 50% of diesel oil by natural gas, the exergoeconomic cost of the produced power is increased by 75%, and the exergoeconomic cost of the produced cold is decreased by 17%. The electric power unit exergetic and exergoeconomic costs indicate that the replacement of diesel oil by natural gas is feasible in the present considerations for engine operation at medium and high loads. [ABSTRACT FROM AUTHOR]