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The following books were written or co-written by members of the I.F.I. personnel and give information on our broad knowledge in different fields of fluid dynamics.

Handbook of Thermoprocessing Technologies

Fundamentals - Processes - Components - Safety Published 2005 by Vulkan Verlag, Essen German Edition of "Praxishandbuch Thermoprozesstechnik", Band 1 & 2

The Handbook of Thermoprocessing Technologies describes its topics in two parts (two volumes in the original German Edition) over 7 main topics that contain up to 88 main chapters each:

Part I   Fundamentals

A     Heating processes

• Some fundamentals of thermodynamics 
• Energy flux in the furnace
• Heat transfer 
• Heat conduction 
• Heating with small Biot number or Sparrow index 

B     Thermoprocesses with gas circulation

• Thermal processing with gas circulation
• Thermal processing plants with gas circulation considered as a flow circuit
• Some fundamentals of fluid mechanics 
• Design of flow ducts in thermal processing plants with gas circulation 
• Gas flow and heat transfer 
• Fans 
• Fast cooling systems by gas circulation 
• Fast cooling by water spray nozzles

C     Thermoprocesses with heat from electric energy

• Resistance and infrared heating 
• Induction heating and melting 
• Dielectric heating 
• Electric arc furnaces 
• Plasma processing for diffusion treatment and coating at low pressures
• Laser beam heating 
• Electron beam heating


Part II   Processes - Componentes - Safety

A     Melting and casting of metals

• Particular process fundamentals
• Melting procedures and casting processes for steel
• Melting processes for iron casting
• Melting processes for non-ferrous metals
• Melting processes for special alloys

B     Heating and heat treatment

• Particular process fundamentals
• Heating
• Heat treatment
• Thermoprocesses for surface technology

C     Construction elements and plant components

• Design principles for thermoprocessing equipment
• Refractory and heat insulation materials
• Refractory design
• Metallic alloys for high temperatures
• Electrical resistance heating elements and electrodes for arc furnaces
• Industrial burners
• Protective gas and reaction gas plants

D     Safety of thermoprocessing equipment

• Safety of equipment with the use of inflammable protective gases
• Explosions protection in thermal process equipment
• Standards adn statutory regulations


ISBN 3-8027-2933-1; 848 Seiten

Prof. Dr.-Ing. Carl Kramer is the predecessor of Prof. Gerhardt at the University of Applied Sciences, Aachen and both worked together with Prof. Grundmann at the I.F.I. Institute for Industry Aerodynamics and within the Ingenieurgemeinschaft WSP (Wärmetechnik – Strömungstechnik – Prozesstechnik; i.e. heat technology, fluid mechanics, process technology). This collaboration was also the origin of the Ingenieurgesellschaft WSP GmbH, who is a reknowned constructor for industrial thermoprocessing plants and specialised heating and heat treatment equipment, e.g. for the bending of glas panes or special metallurgic processes.

In this book Part I, Block B is a co-production of Professor Kramer and Professor Grundmann.

High-Rise Manual

"High-Rise Manual" edited by Johann Eisele and Ellen Kloft Typology and Design Construction and Technology Birkhäuser, Basel - Boston - Berlin, 2003 English Edition of "HochhausAtlas"

With the chapter on wind effects by Prof. Gerhardt and the chapter on facade technology by Lutz and Oesterle

ISBN 3-7643-0274-7; 240 pages, more than 600 pictures and drawings

Double-Skin Facades

"Double-Skin Facades" by Oesterle, Lieb, Lutz, Heusler Integrated Planning Prestel, Munich London New York, 2001 English Edition of "Doppelschalige Fassaden"

Here are the basics to all the aspects of designing a Double-Skin Facade that works:

• Types 
• Building Physics
• Aerophysics
• Construction
• Air-Conditioning and
• Economic Viability

ISBN 3-7913-2504-3; 208 Seiten, 187 pictures and drawings

Rolf-Dieter Lieb, PhD

Publications (English)

Here you will find English book editions and a selection of articles from journals of authors and co-authors from the circle of professors and staff of the I.F.I. Institute of Industrial Aerodynamics GmbH, Institute at the University of Applied Sciences Aachen.

Hoe bescherm je grote zonnedaken tegen hevige winterstormen? - Interview Thorsten Kray NL DEF

Norbert Cuiper


November 30, 2020

Original article at SOLAR365

Daniel Markus, M.Sc.
Available Downloads

Wind Effects on Single-Axis Trackers and possible Stow Strategies

Dr.-Ing. Thorsten Kray

June 9, 2020

Peak Wind Loads on Single-axis PV Tracking Systems

Thorsten Kray, Daniel Markus

The 15th International Conference on Wind Engineering, Beijing, China; September 1-6, 2019

Peak wind loads on a single-axis photovoltaic tracker system were determined based on boundary layer wind tunnel testing. Testing was conducted at two different row spacings, for five different tilt angles and with the model placed at different positions within an array of eight rows. The torque acting on the center chord axis and the normal force acting on typical tributary areas were calculated. Torque and normal force are highly dependent on the tilt angle and row position within the array. In general, loads are higher on the array perimeter. Torque is higher at low tilt angles. Normal force increases with tilt angle at the perimeter, but tends to remain constant from 10° tilt onwards for interior rows. Row spacing also plays a significant role and usually results in an increase of loads. Dynamic amplification factors reveal resonant response occurring at modified Strouhal numbers ranging from 0.06 to 0.14.

PV in need of a new chapter for wind



In part two of this feature on wind resilience in the PV industry, the lack of structural codes comes into focus. Weather events, and wind above all, are the most common causes of failure for PV plants. In the United States, the first steps have been taken to catch up with other industries and a dedicated chapter for PV is set to be included in the next update of the American Society of Civil Engineers code. In Europe, no such plans are in place.


Daniel Markus, M.Sc.
Available Downloads

Tracking in the wind



Extreme wind events are the biggest cause of failure and insurance claims for any PV plant, according to Thorsten Kray, Head of the Building Aerodynamics Department at Institut für Industrieaerodynamik GmbH, Aachen. For structural reasons, single-axis trackers are more prone to the issues than fixed-tilt structures. In this two-part series, pv magazine will examine the ways that wind impacts trackers and what EPCs and investors need to look out for, in addition to outlining a range of approaches from big tracker suppliers that were designed to mitigate wind-related damage.


Daniel Markus, M.Sc.
Available Downloads

Weighing the costs


Ascertaining whether ballast design calculations provided by mounting system manufacturers are performed correctly is not an easy task for the untrained eye. Thorsten Kray, Head of Building Aerodynamics at Institute for Industrial Aerodynamics Aachen (IFI) , has created a checklist for review of ballast calculations which can be used by owners, EPCs, and others involved in designing and realizing projects.


Daniel Markus, M.Sc.
Available Downloads


Thorsten KRAY, Jantje PAUL

EACWE 2017


Pressure coefficients corresponding to peak uplift on low-tilted solar panels mounted on flat-roofed buildings were determined based on boundary layer wind tunnel testing. The solar panels were arranged in arrays of 8 panels by 12 rows. A total of 9 array positions on a total of 11 buildings of different sizes with sharp roof edges were studied. The testing was conducted on a geometrical scale of 1:100 with parts of the testing being repeated at a larger scale of 1:50. Significant effects of array location on the roof, row and panel position within the array, tributary area and building size on peak negative pressure coefficients were found. A refined method for plotting pressure coefficients over normalized tributary area is proposed. In addition, it is shown that at a model scale of 1:50 peak negative pressure coefficients are higher for all array positions and building sizes. This finding may partly be associated with the effects of additional high-frequency turbulence which is not present at the smaller 1:100 scale.

Comparative study of effects on peak velocity pressure calculated by thirty-four European wind loading standards

Thorsten Kray, Jantje Paul

14th International Conference on Wind Engineering – Porto Alegre, Brazil – June 21-26, 2015

The current state of the adoption of National Annexes to EN 1991-1-4 [1] is reported. Moreover, the fundamental values of the basic wind velocity, vb,0, and of the basic velocity pressure, qb,0, for more than 30 countries in the EU and in the adjacent countries are compared. In the next step, peak velocity pressures qp are calculated using a unified fundamental value of the basic wind velocity of vb,0 = 25 m/s, two different terrain categories and building heights of 12 m and 50 m. Only few small countries limit themselves to defining the fundamental values of the basic wind velocity, vb,0. Most countries use the wide variety of opportunities to choose Nationally Determined Parameters (NDPs). Some countries such as Germany and the UK even alter the basic formulae given in the Eurocode which are not allowed for national choices.


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