D. Haillot12*, V. Goetz1, X. Py1and M. Benabdelkarim2

1 PROMES CNRS UPR8521 : PRocess, Materials and Solar Energy Laboratory, Universite de Perpignan Via
Domitia, Rambla de la Thermodynamique Tecnosud 66100 Perpignan, France
2 Saunier Duval Eau Chaude Chauffage Industrie, 17 rue de la Petite Baratte, BP 44315 Nantes Cedex 03

Corresponding Author, didier. haillot@univ-perp. fr

Abstract

A new integrated collector storage (ICS) system is investigated in this paper. This innovative collector includes a composite, made of compressed expanded natural graphite (CENG) and phase change material (PCM), just behind a solar absorber. This composite thanks to its high storage capacity and thermal conductivity, allows storage and release of solar energy at high power level.

ICS, including CENG/PCM composite, has been realised and tested under charge and discharge processes. Comparison between experimental and numerical results allowed us to validate a mathematical model that describes thermal process in the ICS.

Keywords: Integrated Solar Collector, thermal modelling, phase change materials (PCM).

1. Introduction

Integrated solar collector-storage (ICS) system, compared to conventional domestic heating water systems, combines collection and storage of thermal energy in a single unit. Using PCM as storage medium, such system presents several advantages:

• reduction of collector temperature maximum,

• enhancement of the useful efficiency [1],

• reduction or even avoidance of storage tank volume,

• new storage functionality.

Few ICS-PCM have been already studied in several ways (as example, salt hydrate above the absorber[2], paraffin in tube). In this communication we propose a new type of ICS with a composite material based on phase change materials (PCM) and expanded natural graphite (CENG) as storage media. These composite materials are of particular interest in this study due to theirs enhanced properties. They present high storage capacities and high effective conductivity which increases thermal transfer between storage medium and fluid transfer [3]. An ICS prototype (figure 1) including PCM/CENG composites has been realised. The technical feasibility and the obtained thermal performance of the ICS are first described.

The corresponding numerical model describing the thermal process during the charge and discharge of the composite material is presented according to the particular geometry. Then, the obtained experimental results have been compared to the data from numerical model.