Simplified Models for Assessing Heat and Mass Transfer in Evaporative Towers

The aim of this book is to supply valid and reasonable parameters in order to guide the choice of the right model of industrial evaporative tower according to operating conditions which vary depending on the particular industrial context: power plants, chemical plants, food processing plants and other industrial facilities are characterized by specific assets and requirements that have to be satisfied. Evaporative cooling is increasingly employed each time a significant water flow at a temperature which does not greatly differ from ambient temperature is needed for removing a remarkable heat load; its aim is to refrigerate a water flow through the partial evaporation of the same. Often industrial processes require cooling machines or applications capable to remove the heat absorbed during working cycles. Evaporative cooling is the only transformation which is not directly implemented in conditioning systems and, facing high amounts of heat loads one needs to consider the presence of thermal sources which, in nature, act as best receptors for high energy fluxes: atmospheric air, rivers, lakes and sea water. Furthermore it is widely known that, given equivalent thermodynamic conditions, water-cooled exchangers prove more compact and less costly than air-cooled ones. Also, it is important to consider that the necessary quantity of natural water may not be always available for several reasons: physical absence of considerable amounts of water and presence of laws which safeguard the hydrologic environment are the most recurring circumstances that one has to face. In such cases the only solution is a system able to cool continuously re-circulating water. The evaporative tower is precisely the particularly efficient type of exchanger able to realize such a thermodynamic cycle. Table of Contents: List of Figures / List of Tables / Evaporative Cooling / Evaporative Towers Applications / Evaporative Towers Installation / Evaporative Towers Building Criteria / Operating Principle / Water Behavior and Treatment in Evaporative Towers / Zero-Dimensional Model / Zero-Dimensional Model Application / Numerical Analysis / Numerical Solution Methods / One-Dimensional Model Application / Conclusions