Modeling and dynamic simulation of a wet cooling tower

Abstract

Consulta en la Biblioteca ETSI Industriales (7806)

[EN] To everybody, it is well known that environment has changed dramatically during the last 25 years. One of the most important agents responsible of this fact is the atmospheric CO2 concentration. CO2 emissions have been growing constantly every year since the 1950s. As shown in the following graphic, power generation is the sector which sends the higher amounts of CO2 to the atmosphere. In summer, ones of the main contributors to increase the energy consumption are air conditioning systems, whose use has increased dramatically in the last 10 years. Nowadays, most of these systems are based on electrical compression chillers. This increase of electricity consumption is reflected on an important increase of CO2 emissions. At the same time, in summer the demand of hot water and heating decreases considerably. So solar thermal systems do not work at 100% in that season, despite the solar potential is the highest in all the year. That leads to the idea is to use hot water to be able to cool rooms and houses. This hot water can come from different sources such as solar thermal systems or water waste from electric plants. The first option is to take the solar potential to produce cold air. By using solar thermal systems as heat source, we can obtain hot water. Then, we can use that hot water to feed an absorption chiller with small cooling capacities. To make this system able to substitute the traditional electrical compressors, water and power consumption must be maintained at minimum levels. Other possibility we can find is tri-generation. PolySAMART is an EU funded project that consists of investigating the viability of using the system explained in the first option, but using hot water coming from an electric plant. The Institute for Energy Technology of the Technische Universität Berlin is involved in that project in two ways. On one hand, the department has an installation that includes hot water coming from a electric plant, a little absorption chiller, a dry cooling tower and several rooms where temperature is controlled. On the other hand, there is a model programmed on Modelica language, using Dymola program, that simulates the operation of the installation, where it is modeled the heat source, the absorption chiller, a dry cooling tower and the controlled rooms. As it will be seen in its own chapter, PolySMART is a study of trigeneration and the viability to implant this heat solution in the market. This thesis pretends to show the way followed to model and simulate a wet cooling tower using Modelica language and to valid the model. As it will be seen later, several models of this wet cooling tower can be implemented depending on the thermodynamics mathematics used in the study. It will be compared the results obtained with all the models implemented and it will be compared both, the dry and the wet cooling tower as well. It will be compared the results obtained with the virtual model with the measures obtained with the real system as well.