Developing software for the superior efficiency of screw machines

In summary

Screw compressors, expanders and pumps are heavily used for industrial applications, including refrigeration, air conditioning and in oil and gas. The processes in these machines are complex and, before SCORG, the software available to assist with the design and modelling of such machines was rather simplistic. It could only provide limited information and wasn’t able to provide a full analysis or lead to significant improvements.

Professor Kovacevic initially started exploring this area during his PhD in 1999. He used computational fluid dynamics (CFD) to analyse the performance of positive displacement screw machines. It was pioneering work that led to the development of a design and modelling tool for efficient and reliable screw machines.

What did we explore and how?

Although CFD was designed for the analysis of flows in open flows, Professor Kovacevic believed it was also a good starting point for analysing positive displacement machines. This is because it gives a detailed representation of the complex processes happening inside the machine, which are difficult to evaluate experimentally.

The prerequisite for the successful use of CFD is the accurate representation of complex deforming internal flow domains by the numerical grid. This was achieved by applying analytical and numerical modelling to create a convenient numerical mesh for screw machines.

By 2005, the first version of SCORG was available to be tested by industry. It was first used by American company Trane to better understand the internal processes in their refrigeration screw compressors.

As well as assisting with the design of compressors, SCORG is also used to predict potential issues and find ways of correcting them before the machine is manufactured.

Following his PhD, Professor Kovacevic set up the group for CFD research in the Centre for Compressor Technology at City St George's. This has allowed the research to continue, with a number of researchers working in this field to develop the methods for using CFD in positive displacement machines.

Benefits and influence of this research

The main benefit of using SCORG for the design and development of compressors is that it improves the efficiency and reliability of the machines. It allows a variety of methods and software tools to be used holistically for their analysis and design.

Professor Kovacevic’s team gradually developed different aspects to the software, providing companies with an insight into different areas of positive displacement machines. In 2014, the employees at the Centre for Compressor Technology created a spin-off from the university, PDM Analysis Ltd.

This gave the team the chance to further develop and commercialise the SCORG software, as well as to partner with a variety of commercial organisations. Since launching in 2014, PDM Analysis has sold several hundred licences to companies around the world and sales of SCORG totalled over half a million pounds in this time.

However, it is screw compressor manufacturers that have seen the greatest benefits from SCORG. By being better informed during the product development process, they have been able to introduce new, superior screw machines. SCORG has also improved their productivity and profitability.

There is significant interest in SCORG from universities, research organisations and consultants because they can use it to optimise these machines, which, in turn, is highly beneficial for their businesses.

SCORG also has applications beyond screw compressors, expanders and motors. It is used for the analysis and design of gear pumps, vane machines and other devices that have two or more parallel rotors.

Oil-free screw machines are another area where SCORG is proving beneficial. These machines are used in pharmaceutical and food production, and their numbers set to grow exponentially in future. SCORG is an ideal tool to support this new trend, enabling the introduction of efficient and environmentally friendly oil-free screw machines that can be used in other applications.