Experimental Investigations on Falling-Film Absorbers with Horizontal Tubes – a Review

摘要

It is necessary to improve the energy efficiency of all technical processes due to the uncertainties associated withrnclimate change. One possibility to achieve higher energy efficiency is to utilize waste heat which occurs in manyrndifferent applications. This heat may be used to replace compression chillers by heat driven absorption chillersrnwhich leads to a lower consumption of primary energy. Thus, research on heat driven absorption chillers isrnimportant to gain higher energy efficiency.rnIn most cases the absorber is the limiting component of absorption chillers which is often designed as a falling-filmrnabsorber with horizontal tubes. This paper gives a brief overview on the latest experimental results of absorption onrnhorizontal tubes published in the literature. All important design parameters and their influence on the efficiency ofrnabsorbers are considered. This includes the different working fluids and their additives as well as the variousrngeometrical parameters. Thereby, a special focus is put on the different surface structures of the tubes that are usedrnin absorbers. Also recent trends in research as ionic fluids and nanoparticles are examined. As an important result itrncan be concluded that some design parameters and their effects on the efficiency of absorbers are still notrncompletely understood. Due to this, possibilities for further investigations are given.