The CD-Laboratory for Thermodynamics of Reciprocating Engines deals with the analysis of two different types of reciprocating engines, which are build in large numbers. One of them is the hermetic piston compressor for household refrigeration, of which about 80 to 100 million units per year are produced. The other one is the high-speed 2-stroke engine with a production of several million units per year. Due to the enormous numbers even small reductions of energy consumption of the single product will influence the total consumption immensely. In the ongoing research projects the working processes of both machines will be examined using thermodynamic analysis. 0d-, 1d-, und 3d-simulation models will be applied, which are verified with measurement data.
The common basis of both machines is the gas exchange as the fresh gas is sucked into the machine through a suction muffler, and the discharge gas leaves the machine again through a muffler. There are many common physical processes but there are also important differences. Both reciprocating machines produce an instantaneous flow with strong pressure oscillations. Both machines accelerate and decelerate the flow during one cycle within a very short time. Different intake and exhaust respectively discharge mechanisms produce the geometrical boundary conditions for this gas flow. These physical processes influence the working process, the heat transfer, friction losses in the flows and with it the performance.