Proposing a new method for waste heat recovery from the internal combustion engine for the double-effect direct-fired absorption chiller

•Introducing a new waste heat recovery system for use in the direct-fired absorption chiller cycle.•Designing a new generator for direct-fired absorption chiller.•Using the high-temperature water for heat transfer in new generator.•Saving the natural gas consumption of by an average of 90 m3/h.•Reducing NOX and CO2 emissions to 15216.79 and 2492251.2 ton/year by using the proposed system. The use of waste heat in absorption refrigeration cycles is always one of the effective methods of heat recovery that leads to efficiency improvement, energy consumption and pollutants emissions reduction. Accordingly, in this study, a new method is proposed to utilize the waste heat from the exhaust gas of the internal combustion engine (ICE) for a double-effect direct-fired absorption chiller cycle, numerically and experimentally. According to high distance of ICE with absorption chiller, should be used water as working fluid. In this paper, the main goal is to design a new generator for the absorption chiller which provides the required heat from high temperature water instead of combustion heat. In this regard, in the first step, a numerical model is developed to introduce the optimal generator inlet temperature based on energy, exergy, ecoexergy and environmental analysis. Then, the results obtained from modeling is compared with the experimental results. In addition, the inlet temperature of superheated water to the chiller is optimized with multi objective optimization (TOPSIS) method at different concentration of LiBr. Results show that a fuel consumption reduction of 467.7 m3/hr is obtained using the waste heat of the ICE which causes significant decrease 3461.832 kg/year and 1919743.2 kg/year in NOX and CO2 emissions, respectively. It is also concluded that the optimal inlet water temperature of chiller becomes equal to 138 ℃, 137 ℃ and 136 ℃ for of lithium bromide concentration of 0.62, 0.6 and 0.58, respectively.