Modeling of a Double Effect Heat Transformer Operating with Water/Lithium Bromide

Abstract

Absorption heat transformers are effective systems for a wide variety of applications; however, their main purpose is to upgrade thermal energy from several sources at low-temperature up to a higher temperature level. In the literature, several advanced configurations for absorption heat transformers have been reported which are mainly focused on the improvement of the gross temperature lift by the use of a double absorption process; however, these systems usually offer a reduced coefficient of performance. The present study proposes a new advanced configuration of an absorption heat transformer that improves the coefficient of performance utilizing a double generation process. The operation of the new configuration was numerically modeled, and the main findings were discussed and presented emphasizing the effect of several parameters on the system performance. The highest coefficient of performance and gross temperature lift were 0.63 and 48 °C, respectively. From its comparison with a single-stage heat transformer, it is concluded that the proposed system may achieve coefficient of performance values up to 25.8% higher than those obtained with the single-stage system, although achieving lower gross temperature lifts.