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Stefan Heß

Stefan Heß


  • RLS-year 2008
  • Dissertation view

CV from Stefan Heß

Stefan Heß

Stefan Heß was born on April 5, 1983 in Kempten (Allgäu).

He studied environmental and process engineering at the University of Applied Sciences in Augsburg. During his studies he was spokesman of the students´ union executive committee and he acted as students´ representative within the Faculty of Mechanical Engineering. He also was a member of the universities Senat. Stefan Heß graduated in October 2007 with the diploma thesis „Investigations for the Development of a Process Heat Collector with external Reflectors", which he carried out at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg.

Stefan Heß works at the Fraunhofer ISE within the group „Thermal Collectors and Applications" on the development of solar thermal collectors and in the field of solar process heat generation. Within IEA-Task 33/IV „Solar Heat for Industrial Processes" (SHIP) he contributed to a brochure on existing solar thermal collectors for process heat generation ( He also contributed to the German Solar Thermal Technology Platform DSTTP within the working group „Collector Technology". For the Fraunhofer ISE he currently manages the national research project RefleC and the European research project SoPro. He also supervises diploma- and master students.

Short description of the doctoral thesis:

Motivation and abstract of the dissertation: „Generation of Process Heat by Improved Solar Thermal Collectors with Reflectors"

In the countries of EU 27, 28% of the whole final energy demand occurs within the industrial sector. A share of approx. 70% of this energy is heat. There is an especially high potential for the solar generation of heat for industrial processes in the food-, pulp and paper-, textile and chemical industry, since more than 50% of their necessary thermal energy can be provided at temperatures below 200 °C. Other areas of application with very high potential are solar cooling and district heating.

Regardless of this very high potential, up to now there are only approx. 100 plants for the generation of industrial process heat reported worldwide. One reason for this imbalance can be the higher effort to integrate the solar thermal systems into the existing, often very individual heat generation systems. Other reasons often are the short pay back times required by the industry and the lack of suitable, optimized collector technology for some temperature levels and load profiles.

Because of these limiting factors, a target of the proposed research work is the development of a structured approach for the development and optimization of process heat collectors for certain sites and load profiles at temperatures below 200 °C. For the characterization of different collector variants and their optimization for specific industrial processes, for solar cooling and for district heating, simulation calculations using the raytracing program OptiCAD and the transient system simulation program TRNSYS are performed. Special effort is made to model the collectors´ acceptance of diffuse irradiation sufficiently.

Parallel and as a basis of the theoretical work Fraunhofer ISE develops together with the company Wagner & Co. Solartechnik a new process heat flat-plate collector with external, non-imaging reflectors. The new collector is stationary, should be low maintenance and have a high acceptance of diffuse irradiation. Test samples are designed and characterized by measurements at the Test Center for Solar Thermal Systems at Fraunhofer ISE. A demonstration plant will be equipped with a first version of the collector. Therefore basic optimization calculations will be performed. The heat generation system of the demonstration plant will be monitored under working conditions. Considering the measurement data the developed approach for optimization will be further improved, expanded and finally validated.

The scientific supervision of the dissertation is provided by Prof. Dr. Victor Hanby, Institute for Sustainable Energy Development (ISED) at the De Montfort University of Leicester and by Prof. Dr. Ursula Eicker, Hochschule für Technik in Stuttgart.

Thematic areas

  • Naturwissenschaftlich-Technisch
  • Wärme / Kälte
  • Systeme
  • Modellierung / Simulation / Optimierung
  • Experiment / Feldtest

Subject areas

Solar thermal energy engineering


Low-Concentrating, Stationary Solar Thermal Collectors for Process Heat Generation




Low-Concentrating, Stationary Solar Thermal Collectors for Process Heat Generation

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