Screw compressors are essential elements in various industrial sectors, such as manufacturing, energy, and construction, representing roughly 10%–20% of industrial electricity usage. Notwithstanding their prevalent application, the energy requirements of multi-stage screw compressors substantially contribute to carbon emissions. The global market for screw compressors is anticipated to expand at a compound yearly growth rate (CAGR) of 6.5%, achieving a market value of $19.37 billion by 2030. This highlights the increasing demand for more energy-efficient compressor systems. The utilisation of multi-stage screw compressors for applications surpassing 30 bar is constrained by issues including rotor bending deformation, diminished bearing longevity, inadequate oil cooling, and condensate separation in oil separators. Moreover, screw compressors encounter operational constraints in multi-staging, even at reduced pressure ranges, when compared to reciprocating compressors. This study seeks to examine the existing constraints of multi-stage screw compressors and investigates potential solutions for power levels of 22–315 kW and delivery pressures of 6–12 bar. A cost-effective compressor design was designed by utilising modern rotor profiles and optimising sealing and cooling systems. A prototype two-stage oil-flooded air screw compressor, intended for water-well applications, was fabricated and evaluated for performance and dependability. The efficacy of the two-stage compressor was evaluated against that of a single-stage air screw compressor of comparable capacity. An extensive economic evaluation, grounded in lifecycle costs, was performed over a decade. The results indicate that the two-stage compressor reduces operational expenses by roughly 20%–75%, leading to markedly lower lifecycle costs. These insights underscore the capability of multi-stage screw compressors to provide improved performance and economic advantages, promoting broader implementation in applications necessitating mid-range pressures.

High-pressure sectors like mining and construction require multi-stage screw compressors that can operate reliably at pressures over 16 bar. Single-stage compressors frequently encounter constraints such as elevated temperatures, rotor bending deformation, imperfect cooling effect of the injected oil, condensate, and diminished bearing longevity, rendering them inadequate for these specifications. This paper introduces a comprehensive modelling and optimisation approach for multi-stage screw compressors, integrating a physics-based chamber model with machine learning via Gaussian process regression. The framework employs Bayesian optimisation to methodically refine stage-specific parameters, enhancing performance and dependability while ensuring computing economy. The innovation is in its capacity to precisely forecast the performance of both individual and final stages, experimentally validated with a two-stage air screw compressor for water-well applications, attaining an error margin below 5%. A case study illustrated the framework’s efficacy by decreasing specific power usage by 2% via the optimisation of fluid injection parameters. This approach represents a significant advancement in compressor technology, providing a scalable and efficient solution for designing and optimising multi-stage screw compressors in high-pressure applications.

This research focuses on a comparative analysis of two commonly used heat exchanger designs for cooling of lubrication oil (VG32) in centrifugal compressors as shell-and-tube heat exchangers and double-pipe also known as pipe-in-pipe heat exchangers. Shell-and-tube heat exchangers are robust, handling large heat transfer areas and ideal for high-capacity applications. Conversely, double-pipe heat exchangers are simpler in design, easier to maintain, and suitable for moderate heat exchange requirements. Through detailed calculations and thermal analyses using Ansys fluent, the performance of both heat exchanger types was evaluated based on parameters such as heat transfer efficiency, pressure drop, space requirements. Additionally, an innovative approach involving the integration of a double-pipe heat exchanger directly into the centrifugal compressor system was explored, potentially eliminating the need for a separate heat exchanger (Plate type heat exchanger). The study concludes that shell-and-tube heat exchangers can effectively replace existing heat exchangers with improved efficiency, while further research is necessary to ensure the safe and seamless integration of double-pipe heat exchangers with respect to length criteria within the compressor system.

Screw compressors are vital in industrial and commercial applications because to their efficiency, reliability, and longevity. Nonetheless, obstacles persist in improving their energy efficiency and performance, particularly under fluctuating operational requirements. This study examines the influence of critical parameters—specifically, profile clearances, geometric design, and fluid injection strategies—on compressor efficiency and durability. This research presents a thorough investigation of the interdependencies among these parameters, emphasizing the enhancement of compressor performance, in contrast to prior studies. This work is innovative because of its twin approach: first, it experimentally validates the impact of oil and water injection on compressor performance, and second, it utilizes a chamber-based model to analyze the implications of various parameters in greater detail. The experimental results demonstrate that water injection reduces specific power consumption by 4.59% compared to conventional oil injection, highlighting its potential for enhancing energy efficiency. This study offers significant insights into compressor design and operation, identifying optimal designs for diverse applications and pressure ratios. The findings enhance the comprehension of parameter interactions and fluid injection impacts, aiding in the advancement of more sustainable, high-performance screw compressors.