S. Brandmayr1*, M. Konrad1, W. Zorner1 and V. Hanby[2]

1 Ingolstadt University of Applied Sciences — KompetenzzentrumSolartechnik, Esplanade 10,

85049 Ingolstadt, Germany

2 De Monfort University, Institute of Energy and Sustainable Development, The Gateway,
Leicester LE1 9BH, United Kingdom
* Corresponding Author, sebastian. brandmayr@fh-ingolstadt. de

Abstract

This paper describes with the R&D activities at Ingolstadt University of Applied Sciences in terms of thermosiphon solar hot water systems. The simulation tool Matlab/Simulink and CARNOT was enhanced by a double mantle heat exchanger storage in order to be able to investigate the behaviour of all kinds of thermosiphon systems in theory. Taking data measured at the university’s thermosiphon testing rig into the simulation models, provides the possibility to improve systems by all relevant parameters without performing additional outdoor tests.

Keywords: simulation, Matlab/Simulink, thermosiphon system, storage, development

1. Introduction

Thermosiphon solar hot water systems have been a subject to R&D activities of the Kompetenzzentrum Solartechnik (Centre of Excellence for Solar Engineering) at Ingolstadt University of Applied Sciences since 2004. After building up a test rig, several thermosiphon systems were tested according to the specifications given in ISO 9459-2 [1]. In addition to that, tests according to methods and procedures developed at Ingolstadt University have been carried out in order to learn about the system’s behaviour under special conditions, e. g. its stagnation behaviour.

In the end of 2007, a R&D project was started which aims at the development of an optimised thermosiphon system based on scientific results. A market analysis carried out beforehand showed that most thermosiphon systems are still developed through trial and error [2]. This project, however, aims at demonstrating a closed development cycle. This cycle includes the analysis of thermosiphon systems in theory, the transfer of the mathematical model into simulation, the design of a prototype based on the simulation results and, eventually, the testing of the prototype in order to maximize the system performance and to achieve validation of the computer model. This validated system model is going to offer the project partner, a manufacturer of solar thermal applications, the possibility of adapting their thermosiphon systems to the customers’ and climatic conditions.

blockset (Conventional And Renewable eNergy systems Optimization Toolbox [4]), which is a tool for the calculation and simulation of the thermal components of heating systems with regard to conventional and regenerative elements, was used. It provides models for heat sources, storage systems, hydraulics and fundamental material calculation as well as the possibility of integrating further models. The models used, except the developed double mantle heat exchanger storage, were validated by Hafner et al [4].