• Cascading of Absorption refrigeration with Single Mixed refrigerant LNG process. • Using intercooler waste heat from SMR compressors to drive ARS generator input. • ARS provides further cooling effect using energy consumed by SMR compressors. • Improving COP and exergy efficiency by 14.47% and 2.51% respectively. • Thermodynamic and parametric analysis of the cascaded SMR–ARS system. Natural gas liquefaction relies heavily on Single Mixed Refrigerant (SMR) systems, which inherently suffer from substantial exergetic losses during multistage compression. The intercoolers reject significant quantities of low-grade heat to the ambient environment. This represents a major thermodynamic inefficiency. This study focuses on a hybrid process of harnessing of waste heat from the intercoolers of multistage compressors in the SMR process to drive an Absorption Refrigeration System (ARS). This cascading of ARS with SMR-LNG process using intercooler waste heat has not been explored in existing literature, representing a novel approach to enhance cryogenic process sustainability. The core novelty lies in this internal cascading of intercooler waste heat, which supplements the primary cryogenic cooling demand without requiring auxiliary fuel inputs. The mathematical framework of cascaded ARS with the SMR cycle was modeled using REFPROP library of Python and was validated against benchmark literature data. A detailed parametric analysis was subsequently conducted to quantify the system's dynamic response to five critical operational variables: mixed refrigerant flowrate, feed flowrate, cooling water inlet temperature, compression ratio, and specific interstage temperatures. Improvements in combined performance, cooling effect, and energy and exergy efficiencies were observed, the cascaded configuration successfully recovers approximately 30% of the available intercooler waste heat. This cascaded system elevates the total system cooling capacity from 738.7 W to 845.6 W, translating to a 14.47% enhancement in the overall Coefficient of Performance (COP), which improved from a baseline of 2.069 to 2.368. The results demonstrate that the proposed internal heat cascading framework provides a highly viable and sustainable pathway for controlling exergetic losses and boosting operational capacity in natural gas liquefaction networks.
Nasif et al. (Fri,) studied this question.