Parameter analysis and energy optimization of a four-bed, two-evaporator adsorption system

A four-bed two-evaporator adsorption chiller is a promising and environment-friendly technology that utilizes waste thermal/renewable energy to produce chilled water and high-grade potable water simultaneously. Unlike existing works that focus solely on improving chillers’ cooling performance under constant ambient conditions, this work develops optimal cycle time correlations, factoring varying external conditions, to maximize specific daily water production of a multi-bed adsorption chiller prototype. A poor selection of its operational parameters can negatively impact the chiller’s performance, particularly when the cooling and potable water demands vary. Accordingly, a dynamic-based model has been judiciously developed to study the operating characteristics of the chiller. Further, Monte Carlo simulations are employed to assess and rank the influencing strength of key operating parameters on the chiller’s performance. The parameter sensitivity on the chiller’s performance in terms of improving its cooling capacity, coefficient of performance, and specific daily water production are statistically analysed. Experiments have also been performed to validate the dynamic model. Comparisons showed good agreement between simulated specific daily water production results and experimental data with a maximum discrepancy of 4.1%. The developed correlation is able to estimate the chiller’s optimal cycle time with an R-square of 0.96. Key results revealed that the respective hot and cooling water mass flow rates entering the chiller are the most influencing parameters that quantify the chiller’s coefficient of performance. And chilled water mass flow rate and cycle time are critical parameters that impact the chiller’s cooling capacity, while the operational cycle time dictates its specific daily water production.