Entropy Flow Analysis of Thermal Transmission Process in Integrated Energy System Part I: Theoretical Approach Study

• Published in: Processes 2022-09, Vol.10 (9), p.1717
• Main Authors: Chen, Changnian, Wang, Junjie, Zhao, Haoran, Yu, Zeting, Han, Jitian, Chen, Jian, Liu, Chunyang
• Format: Article
• Language: English
• Subjects: Analysis; Convection; Electric power transmission; Electricity; Energy transmission; Entropy; Finite element analysis; Force and energy; Heat loss; Heat transfer; Integrated energy systems; Mathematical models; Parameters; Partial differential equations; Pipes; Radiation; Thermal energy; Thermodynamics
• ISSN: 2227-9717; 2227-9717
• DOI: 10.3390/pr10091717

It is very important to accurately describe the dynamic processes of thermal energy transmission for coupling with Integrated Energy System (IES). In order to study the thermodynamic characteristics of heat supply, this paper theoretically suggested a generalized model of entropy flow by deducing the expression of entropy conduction and convection based on thermodynamic law and heat transfer analysis. Taking temperature and entropy as the intensity and extension properties, the equivalent distributed and lumped parameter models are established to describe the features of heat loss and transmission delay. The effectiveness of current models is verified by comparing with solutions of conventional Partial Differential Equations (PDE) of heat transfer. The numerical simulation and verification procedure were conducted by Matlab/simulink. The proposed models were applied to simulate the response of temperature and entropy flow of a pipe with length of 100 m under different discrete conditions. The results show that for a distributed parameter model the maximum relative error is 1.275% when the pipe is divided into 100 sections, and for a lumped parameter model, the overall relative error is in the order of 10−3, which can be ignored in practical applications. All these prove the correctness of proposed models in this paper.