Efficiency of shock wave compression in a microchannel

The efficiency of compression processes tends to decrease dramatically when the overall dimensions are scaled down to micron level. Then it can be assumed that the compression is more efficient if no moving parts are involved in the process. This is achieved by replacing, at least partially, turbo-compressor stages with a wave rotor. The work starts with estimating wave rotor efficiency at microscale by extrapolation. Then, an analytical model is introduced from which the theoretical efficiency of compression process in a microchannel is deduced. Knowing the inlet conditions and the pressure gain across the shock, the overall efficiency of the compression can be calculated. The model assumes constant friction along the walls and no heat exchange with the surroundings. The results suggest that an efficiency of 70–80% can be achieved in the channels of an ultra-micro wave rotor. It is shown that if the inlet temperature is high enough (about 1500 K), the efficiency is even higher, up to 90%.

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