4E analysis of novel waste heat-driven combined cooling and power (CCP) systems based on modified Kalina-ejector refrigeration cycles

Global warming and environmental pollution are becoming increasingly severe problems due to the excessive use of fossil fuels. Recovering and utilizing waste heat from different energy systems can considered a sustainable solution to this destructive trend. This study proposes two modified Kalina cycle structures that use ejector refrigeration for combined cooling and power (CCP) generation in low-temperature waste heat. While to recover energy from a lean ammonia solution uses a two-phase expander. Thermodynamic analysis shows that the modified Kalina cycles E and F operate with a thermal efficiency of 0.3066 and 0.2557, respectively, representing a significant improvement of more than 123 % and 86 %, respectively, compared to the base cycle. Also, the exergy efficiency of the improved configurations E and F has been calculated as 0.083 and 0.089, respectively, showing an improvement of 53.8 % and 64.8 %, respectively, compared to the base cycle. The exergoeconomic analysis also revealed that the total capital cost rate for improved cycles E and F is estimated at 2.62 and 2.76 $/h, respectively. In addition, from an environmental perspective, the improved Kalina cycle F has proven to have a more eco-friendly performance with a pollution index of 0.2281 mPts/s. Moreover, a parametric study is conducted to investigate and analyze the effect of changes in significant performance parameters such as ammonia concentration, evaporator temperature, turbine inlet temperature and pressure, and turbine back-pressure for both presented modified cycles.