Thermal Process Engineering Laboratory

Process engineering deals with the technical implementation of processes that specifically change substances according to type, property and composition. Thermal process engineering is about processes that have to do with heat, especially heat transfer. How can heat be applied to a product and thus, for example, separate components from a mixture? Thematically, the focus is on thermal separation processes such as drying, distillation / rectification, absorption, adsorption, extraction and crystallisation.

The students complete their practical training in the well-equipped facilities of the thermal process engineering department - a laboratory and a pilot plant. Thus, a wide range of drying apparatus is available for the training, with which (almost) any food can be dried. The spray dryers, which are very widespread in the food industry and are mainly used in the dairy industry for the production of milk powder, are available here on a smaller scale for teaching purposes. Two fluidised bed granulation plants enable, among other things, the granulation and coating of originally powdery products. To evaluate the raw materials used and the products produced, the technical centre has modern analytical equipment, such as a digital microscope or a laser diffractometer to determine particle size distributions in powders or granulates. The laboratory equipment can also be used for project work and research activities.

The topics of the practical courses from the compulsory as well as the compulsory elective area, with which the students apply and deepen their acquired knowledge from the lectures, are "Thermal Process Engineering", "Drying Technology", "Heating and Refrigeration Technology" and "Food Process Engineering". One focus is on drying technology. Within the scope of this subject area, the students determine characteristic drying processes of different products. In addition, they learn how to produce milk powder themselves, in particular how to influence the production process so that certain properties such as solubility or particle size - the powder must not dust, for example - are guaranteed. Furthermore, the students gain insights into the process of freeze-drying. This form of drying is used for temperature-sensitive products or products whose outer shape is to be preserved during drying, for example pieces of fruit. In regular student project work, aroma and alcohol-containing red wine granulates are also produced.

Research activities occupy a large area. This includes research work within the framework of doctorates as well as final theses (Bachelor and Master). Special equipment such as a levitator can be used for this. This can be used to keep individual droplets in suspension and observe their drying under various conditions. Another research topic is the encapsulation of microorganisms, which should make it possible to stabilise probiotic bacteria in such a way that they can reach their site of action, the human intestine, in sufficient numbers.

The equipment of the laboratory and the pilot plant is of high quality and extensive:

• Digital microscope to assess e.g. granulates (structure, surface, particle size).
• Fluidised bed granulation apparatus: This device can be used to produce granulates or encapsulate probiotic bacteria, for example.
• Heat exchanger experimental set-up: This experimental set-up can be used to experimentally teach the basics of heat transfer with different types of heat exchangers (e.g. plate, tube bundle or double tube heat exchangers).
• Spray dryer for producing e.g. milk powder
• Freeze dryer: This device can be used to dry products that have to be dried gently because they cannot tolerate temperature.
• Levitator for preliminary tests for spray drying, in which single drops are examined
• Hardness tester (analyser) for testing the hardness of small particles - measures the point - force and path - at which a particle breaks
• Laser diffractometer / Mastersizer 2000 (analyser): This apparatus can be used to measure particle size distributions in powders or granules, e.g. from a spray-dried product.
• Differential scanning calorimetry (DSC) device: This device can be used to determine the properties of substances, e.g. the melting or crystallisation behaviour of food or the raw materials used.
• Magnetic levitation balance for measuring sorption equilibria - how much moisture does a product absorb depending on the ambient humidity?
• Density meter: This device can be used to measure the density or specific gravity of liquid substances.
• Rotary evaporator: This device can be used to remove water from a liquid in a vacuum. For example, milk can be concentrated before it is put into the spray dryer.