Session: 37-03 Radial Turbomachinery CFD

Paper Number: 151150

Liquid Injected Seal to Reduce Leakage Flow in a Refrigerant Compressor 

The leakage flow through a traditional labyrinth seal reduces the compressor efficiency of an oil-free magnetic bearing centrifugal compressor. Also, the leakage flow pollutes the downstream coolant flow reducing its motor cooling capacity. A novel design is introduced to utilize the pressure loss across the seal, by injecting liquid refrigerant near the seal inlet. The liquid injected seal also functions as an expansion valve, producing low temperature saturated liquid at the seal exit. The saturated liquid is projected to be utilized for motor cooling. A multiphase numerical simulation is performed to quantify the compressor performance of the liquid injection seal and traditional seal under adiabatic condition. The numerical simulation utilizes a Eulerian-Eulerian approach with equilibrium phase change model. In this study, the compressor performance is evaluated at three speed lines: 20,000, 30,000, and 38,000. The base case results are validated with the experimental findings, with a maximum error of 3% in compressor efficiency. The local distribution of pressure, mass fraction, and temperature are analyzed. The numerical results show the leakage flow in the liquid injection seal is reduced by 90%, and the efficiency of the compressor is increased by 2%. Also, the liquid injection seal cooling capacity is quantified at different operating conditions.

Presenting Author: Karthik Krishna Danfoss

Presenting Author Biography: Karthik Krishna, Ph.D., is a Senior Aero-Thermal Engineer at Danfoss LLC, based in Tallahassee, FL. He earned his Ph.D. in Aerospace Engineering from Embry-Riddle Aeronautical University, where he also served as a Visiting Assistant Professor. His research interest are turbomachinery, multi-phase simulation, and aero-acoustics modeling.

Authors:

Karthik Krishna Danfoss
Jin Yan Danfoss