hot gas generator - HGG

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The requested „Großgerät“ namely the hot gas generator (HGG) will provide the hot gas for three testing modules of the Institute of Power Plant Engineering and Heat Transfer (IKW). Two IKW working groups (WG) are involved in this proposal, the WG Rankine Cycle for Waste Heat Recovery Applications and the WG Heat Transfer. The WG heat transfer is divided into the research areas Packed Beds and Complex Tube Geometries. The research projects of both WGs are outlined below.The WG Rankine Cycle for Waste Heat Recovery Applications will develop a novel approach for a holistic optimal design process of Rankine cycles. The aim is to locate a combined optimum for the working fluid, the circuitry, the design and the size of the Rankine cycle components. Currently no such optimization method is specified in the literature which would allow conclusions to be drawn about the size of the components. The focus is on the modeling of the expander. This working engine when optimally designed offers great potential in dynamic systems. The existing Organic Rankine Cycle testing module at the institute should be operated with the HGG to provide a basis of data for this project.In the research area of Packed Beds, the precise influence of radiation on heat transfer in monodisperse packed beds will be investigated and modeled. Measurements at temperatures up to 800 °C will form a base for the models. The hot gas for these measurements will be provided by the HGG. With the help of a specially developed method for image recognition, it is intended to take the particle arrangement into account to serve as a basis for numerical models of heat transfer. This will ensure geometric similarity of simulation and experiment. The validation of the numerical models shall be carried out by means of using measurement data. The gained knowledge shall be extended to polydisperse packed beds.In the research area of Complex Tube Geometries passive and active measures are to be investigated with regard to the improvement of the heat transfer and their influence on the pressure loss. Passive measures are longitudinal twisted and surface deepened tubes. Active measures are surface vibrations and acoustic excitations. Heat transfer and pressure loss will be investigated in numerical models and compared with experimental data. The basis for the measurements is the hot gas flow provided by the requested device. The measurements will be carried out over the entire mass flow and temperature range. This leads to Reynolds numbers of 550 to 140.000 in the range of 20 - 800 °C and thus also covers high-temperature applications.