Aqueous lithium bromide absorption refrigeration systems have been studied in recent years and their advantages like environmental safety and utilization of low-grade energy have been proved. Research on improving their performance has been increasing lately. In this paper, single effect and parallel flow double-effect aqueous lithium bromide absorption refrigeration systems have been studied. Mass, energy, entropy and exergy balances have been used to model the absorption refrigeration systems. Parametric studies have been done to investigate effects of cooling load, evaporator exit temperature, condenser exit temperature, generator vapor exit temperature, absorber exit temperature, solution energy exchanger effectiveness on the performance of the system. The analyses show coefficient of performance and exergetic efficiency of double-effect absorption refrigeration is higher than those of a single-effect refrigeration. The effect of other parameters on performance of both single and double-effect systems have been described in detail in the article.