GERMANY: A new research unit looking at increasing the efficiency of heat pumps has been established at Germany’s Chemnitz University of Technology with €4m of funding from the German Research Foundation (DFG).
The new Archimedes research unit will initially seek to understand the behaviour of the typical oil-refrigerant mixtures in the compressor of a heat pump, something that is not currently fully understood thermodynamically.
“The behaviour of a mixture of lubricating oil and refrigerant – such as the natural refrigerants propane or CO2 – in the compressor of a heat pump or refrigeration machine is a particular challenge for thermo- and fluid dynamics,” said Professor Markus Richter, Chemnitz University of Technology’s head of the professorship of technical thermodynamics.
“Factors such as pressure and temperature change the thermophysical behaviour and thus the flow behaviour, which ultimately has an influence on the heating or cooling performance.”
The research aims to precisely determine the thermophysical properties for oil-refrigerant mixtures and, based on this, develop simple applicable equations of state as well as models for viscosity and thermal conductivity.
“To develop a comparatively simple calculation model for the flow behaviour of oil-refrigerant mixtures in gaps of compressors, we need precise information about how these fluid mixtures behave thermodynamically. The actual gap flow is then examined in a generic experiment of a rotating contour in a cylindrical glass housing. Here, we characterise the flow behaviour on a macroscopic level with laser-optical methods and on a microscopic level with high-resolution numerical simulations,” added Professor Andreas Brümmer, head of the chair of fluidics at TU Dortmund.
The research work is scheduled to begin in the first quarter of 2024. In addition to Chemnitz University of Technology and TU Dortmund, TU Dresden, Friedrich-Alexander-Universität Erlangen-Nürnberg, Karlsruhe Institute of Technology, Ruhr University Bochum, and RWTH Aachen University are also involved in the Archimedes research unit.