Novel Conceptual Models for Thermodynamic Analysis of Urban Water Systems

Li Luo, Xiaochang C. Wang, Wenshan Guo, Huu Hao Ngo


ABSTRACT: Urban water system (UWS) can be thermodynamically analysed by calculating the entropy budget based on the increase of entropy due to internal and/or external contributions. From different internal and external parts, two novel conceptual models of thermodynamic analysis for an UWS were proposed. For conceptual model 1, natural UWS as a pseudo-reversible process is internal contribution, while the external part of the UWS is artificial water cycle. When the entropy change of the natural UWS is equal to zero, the entropy change of the UWS is considered as the entropy change by the artificial water cycle. The calculations of entropy change for artificial water cycle are based on water balance and purification reactions of selected kinds of typical pollutants in the UWS. For conceptual model 2, the internal entropy change of the UWS is water body, and it is assumed to be zero due to dynamically equilibrium of the water body. The calculation of external entropy change caused by the natural water cycle was proposed to be dependent on meteorological and hydrological data whilst the external entropy change caused by the artificial water cycle could be obtained from mass balance and treatment process analysis.


Keywords: urban water system; thermodynamic analysis; entropy; conceptual model