Experimental study of ammonia-water absorption assessed in real conditions of operation of the refrigeration cycle

Abstract

Heat absorption refrigeration cycles have advantages when compared to conventional mechanical steam compression systems in several aspects. First, with regard to direct consumption of electricity, since they use considerably less electricity to operate. Second, they can operate with residual heat sources, such as cogeneration, or with solar thermal energy. In the latter case, it is part of the objectives of the ongoing thematic project, FAPESP No. 2016/09509-1 (Heat transfer processes with high-performance phase change applied to the use of solar energy) in which the supervisor is a main researcher. However, the technology of heat-absorbing refrigeration equipment is still dominated by a few international companies and none in the country. Nevertheless, efforts have been made at the SISEA Laboratory - (Alternative and Renewable Energy Systems Laboratory) to master this technology, especially the heat absorption cycles based on the ammonia and water fluid pair. This effort received support from FAPESP through projects already 2010/10858-4 (already closed) and FAPESP No. 2016/09509-1, in progress. In this sense, the present project has as a general objective to continue the experimental study of the ammonia-water absorption process under real conditions of operation of the refrigeration cycle, seeking to improve the heat and mass transfer coefficients, as well as to develop new technologies of absorption plates in order to make the equipment more compact and efficient. The refrigerated workbench already built will be used to study the behavior of the absorption process under the effects of the variation in the conditions of entry into the absorber such as temperature and mass flow rate of the weak and strong solution, absorption pressure, vapor mass conditions, and among others. Experimental results will allow to evaluate the performance of the absorption process for real cycle operating conditions, allowing to compare these results with the theoretical results. In addition, the project will employ heat transfer techniques to the absorber and the generator through technologies under development within the scope of the aforementioned thematic project underway. Such techniques may employ heat tubes and microchannels, as has been developed by other members of the thematic project. (AU)