Comparative study of the impact of the dummy port in a scroll compressor

A dummy port plays an important role in the porting process and the improvement of the performance of a scroll compressor. This paper documents an investigation on the working mechanism of the dummy port in a scroll compressor. To characterize the dummy port effects on the different parts of the scroll compressor, two scroll compressors, one with and the other without a dummy port, are studied comparatively. The flow through the dummy port is examined in the background of an integrated compressor working process. The assembly of the compressor under investigation includes the upper bearing housing, scrolls, check valve, and discharge plenum. The Navier–Stokes equations with a k–ɛ turbulence model are solved at the standard operating conditions of a scroll compressor. Refrigerant-22 is used as the working fluid. The thermodynamic and transport properties of the refrigerant gas are modeled by the Martin–Hou equation of state and power laws, respectively. Global flow physics is investigated first to lay a foundation to understand the working mechanisms that control the porting process before averaging techniques are applied. The behavior of the gas pockets in the porting process is characterized in both geometric and dynamic nature. The time-dependent variation of volume, mass, energy, and volume-averaged field quantities inside the gas pockets are studied throughout the porting process. The impact of the dummy port on the compressor performance is defined.