Investigating Alternative Rotor Materials to Increase Displacement and Efficiency of Screw Compressor While Considering Cost and Manufacturability

Screw compressor, a rotary positive displacement machine, has gained popularity and is one of the most commonly used types of compressors across the globe due to better efficiencies and high reliability. The most vital component on which the screw compressor functions are the screw rotors, enclosed inside the housing with minimal clearances. Hence, the design of the rotors plays a significant role in affecting the thermodynamic performance. Also, it is found that profiles with a greater depth deliver a larger flow with higher volumetric and adiabatic efficiencies than their counterparts of the same size with a smaller profile depth [1]. In this paper, structural analysis of the screw compressor block is carried out to examine the effect of stresses, thermal gradients and deformation for different rotor materials for a 4/5 lobe combination. This alternative material investigation further influences the rotor profile depth for the same main rotor outer diameter, enhancing displacement and efficiency by 5.01% and 1.1%, respectively. Factors such as manufacturability and production cost of screw rotors have also been considered to fairly evaluate the commercial feasibility of alternative materials. Besides enhancing performance, the selected materials improve other essential properties, such as corrosion, bio-compatibility and wear resistance. The future study proposes a 3/6 lobe combination screw rotors to be considered for a significant amount of improvement in performance with smaller root diameter for numerical analysis and to be validated experimentally.