Falling-film as natural cooling technique: Modelling and energy impact assessment

Abstract

Although the cooling energy consumption is expected to decrease with the use of natural cooling techniques, their incorporation into the building sector remains very limited in most countries of the European Union and non-existent in others. This is largely due to a lack of information about the techniques and tools that enable the different design options to be assessed quickly and without high computational costs. For this reason, this study develops a simplified characterization model of the falling water film system since there is a lack of available information about it. This makes it possible to assess the system’s potential in a variety of operating conditions or climate zones and to evaluate it as an alternative or complement to conventional air conditioning systems. This model has been obtained and validated with data provided by assessing an experimental prototype of the system. This simplified characterization model allows the Transient System Simulation Tool to assess the energy impact resulting from the use of falling water film technology to supply cold water to an air treatment unit through a thermal energy storage system. The energy impact was assessed for different kinds of single-family homes and in the two most extreme climate zones regarding cooling. The results show that this natural heat dissipation system is capable of satisfying up to approximately 90% of the demand for the different kinds of homes and climate zones studied. The maximum percentage of the demand satisfied can be obtained with different storage tank volumes and dissipation areas. Thus, when studying how to incorporate this natural cooling technique, it is necessary to analyse the optimal energy and financial cost of the range of design options according to the case in question. Finally, thanks to the set of simulations carried out, it has been possible to define the concept of the utilization factor, which will allow for the easy evaluation, without the need for detailed simulations, of how the system can be incorporated into buildings in future studies of climate applicability.