Dynamic modeling of a coupled heat pump system – thermal storage by phase change materials. Systemic approach and experimental validation

Etudiant :Jing WU

Ecole doctorale :Array

Directeur ou Directrice :C. Jallut, E. Gagnière

Financement :ANR ACLIRSYS 2011-2015

Date de la soutenance :20151008

Abstract

In the area of buildings refrigeration, the use of thermal energy storage coupled with heat pump is a significant way for reducing the operating costs and optimizing the design of equipment. A prototype of refrigeration-PCM (Phase Change Material) energy storage system is built and implemented within the framework of the project ACLIRSYS (Advanced Control for Low Inertia Refrigeration Systems), funded by the French National Research Agency. The objective of my PhD thesis is to propose a dynamical physical model for the complete system.

Within the evaporator and condenser of the heat pump, the refrigerant can be liquid, vapor or mixture of both, while the storage media can be solid, liquid or a mixture of both. Therefore, it is necessary to consider the discrete events associated to phase changes in order to solve the energy and mass balances in different configurations. In this work, static models are used for the compressor and the expansion valve of the heat pump. The heat exchangers of the heat pump and the storage models are based on a representation of the fluid flows by a cascade of Continuous Stirred Tank Reactors (CSTRs). In order to assure the continuity of system evolution, the switching mechanism between different configurations is established. This switching is performed by matrix operations, which permit to achieve a global and very compact representation of the system. The thermodynamic properties of the refrigerant and their partial derivatives are analytically determined by using an equation of state. Two versions of the model for the storage are proposed. A simplified version where the supercooling is assumed to take place at a constant temperature and a more detailed version based on the population balance equations.

Experimental data from the prototype has been used to validate the developed model. Experiments in transient states were performed by varying the operating conditions. These date relate to the functioning of the heat pump alone, the storage alone and the coupled system. A very good agreement between the numerical results and experimental data was obtained.Le modèle qui sera développé permettra de connaître le comportement dynamique du dispositif complet et servira d’outil d’aide à la conception du système de commande de l’ensemble. Le modèle développé sera basé sur une approche thermodynamique et sur l’application des principes de conservation (matière, énergie, quantité de mouvement). Des expérimentations réalisées au CNAM et chez CIAT permettront de valider les résultats de simulation.

  • Auteur : Jing WU direction de thèse : C. Jallut, E. Gagnière
  • Soutenance :le jeudi 8 octobre 2015 à 10h dans l’Amphi Thémis 7
  • Financement : ANR ACLIRSYS 2011-2015