Compressor Technology
  1. SCORPATH
  2. SCORG
  3. DISCO
    1. SCORPATH
    2. SCORG
    3. DISCO
Compressor Technology
Holroyd Precision Ltd

Centre for Compressor Technology

Research and developments of twin screw machines made at the centre have led to great improvements in their performance, reduced manufacturing costs and increased range of application. Consequently, we are internationally recognised as a centre of excellence.

Fundamental theoretical and experimental studies applied to twin screw machines have led to a greatly enhanced understanding of their mode of operation and the development of software to optimise their design, which is now widely in use by industry. The scope of this work is being continually extended beyond positive displacement machines to increase the range of operating conditions at which they are viable, improve their ability to contain two-phase flow processes and to investigate new and, as yet, untried configurations.

About the centre

Our vision

To extend the boundaries of understanding of machines for compression and expansion processes, thereby:

  1. enabling them to operate more efficiently over a wider range of conditions, with aim to reducing both environmental impact and manufacturing costs;
  2. utilising such machines in novel configurations for improved recovery of power from low grade heat; and
  3. serving as an aid to industry in the design, manufacture and operation of such machines, both in existing and novel forms.

Expertise and capabilities

Funded mainly by industrial contracts, but with some input from public funding, members of the centre have developed software for  improved analytical modelling of both compression and expansion processes, the use of computational fluid dynamics for more detailed studies, including solid-fluid interaction and noise reduction and test facilities for both air and refrigerant compressors and detailed internal flow measurements.

By this means, apart from its ongoing research activities, the centre is able to investigate and solve industrial problems, offer courses in machine design both to registered students and industrial engineers, license proprietary software and, if required, carry out the complete design, build and testing of prototype machines for industry.

Additionally, the centre organises and hosts a biennial International Conference on Compressors and their Systems, which is sponsored by the Institution of Mechanical Engineers (IMechE), the Institute of Refrigeration (IOR) and leading industrial manufacturers.  This has been functioning since 1999 and is a leading forum for academic, research and industrial organisations concerned with  the development of fluid machinery.

Centre members have been granted 12 patents, published three monographs,  85 journal papers, 166 conference publications and over 200 industrial reports, for which they have received 13 professional awards and prizes.

Key research activities

  • Rotor profiling and screw machine performance calculation
  • Utilisation of low temperature heat sources by using screw expanders
  • Research in multifunctional screw machines
  • Multistage screw compressors for high pressure difference applications
  • Computational fluid dynamics (CFD) in screw machines
  • Laboratory investigation of screw machine working processes
  • Investigation of multiphase and leakage flows in screw machines
  • The use of composite materials and additive manufacturing techniques
  • Noise in rotating machines
  • Multiphase flow modelling and experimentation

Services offered

  • Project evaluation
  • Software development
  • Fault investigation
  • Thermodynamic and fluid flow studies
  • Stress analysis
  • Instrumentation and control
  • Laboratory measurements
  • Noise suppression
  • Complete product design and development

Software program suites

  • SCORPATH – Screw Compressor Optimal Rotor Profiling and Thermodynamics
  • SCORG – Unique grid generation and analysis of screw machines
  • DISCO – Design integration interface for Screw Compressors

History

Following three years of collaborative work between Professor Ian Smith, who was attempting to develop screw expanders, for recovery of power from low grade heat, at City, University of London, and Professor Nikola Stosic of the University of Sarajevo, who had significant experience in the development of similar machines as compressors, the centre was established in 1995, when Nikola Stosic was awarded a Royal Academy Professorship, with industrial co-sponsorship by Holroyd, of Milnrow, Lancs.

Professor Ahmed Kovacevic, who had been working on screw compressors since 1986, joined them in 1996 and pioneered the application of Computational Fluid Dynamics to evaluate the screw machine performance.

Latterly, they were joined by Dr Elvedin Mujic, who made a significant contribution to noise reduction and who now holds a senior position in industry, and subsequently by Dr Ashvin Dhunput, who also now holds a senior industrial position. More recently, they have been joined by Dr Matthew Read, who is now a lecturer in the School of Mathematics, Computer Science and Engineering. He makes a significant contribution to integrating expanders into power recovery.

Portrait of Ian Smith

Professor Ian Smith

Research

Important contributions have been made in various aspects of application of compression and expansion technologies and educations such as:

  • Patents for the “N” rotor profile in 1996 and 2013.  The “N” rotor profile is now the industry standard and has generated significant income for City.
  • Trilateral Flash Cycle and Wet Steam Cycle for improving the efficiency and reducing the cost of power recovery from low grade heat sources.
  • Four fully equipped laboratory test rigs for compressors and expanders, built to meet highest industrial standards.
  • Holding a Royal Academy Chair in Positive Displacement Technology between 1995 and 2000.
  • Introduction of the Howden Chair in Engineering Design and Compressor Technology in 2008.
  • Supporting Electratherm, Reno, Nevada, USA since 2005 in their development and marketing of screw driven Organic Rankine Cycle (ORC) systems for waste heat utilisation.
  • Establishing Heliex Power Limited in 2009, as a spin out company from City, University of London for use of steam driven screw expanders for waste heat utilisation.
  • Establishing postgraduate courses in Mechanical Engineering at City, University of London, providing a Master of Science education to more than 300 young engineers in screw machine technology through the unique theory and laboratory courses.
  • PhD students have been supervised by centre members, leading to their successful doctoral grades in area of Thermodynamics, Fluid Mechanics, Computational Fluid Dynamics, Metrology and Tribology in positive displacement technology.

Recently the centre has been joined by a group with extensive expertise in materials, focusing on numerical and experimental research in composite materials and manufacturing processes.

Selected funded research projects

Principal investigatorCo-investigatorsProject titleFunderAmount awarded to City (excluding partners)Start dateEnd date (including no-cost extension)
Professor Ahmed KovacevicDr Sham RaneHowden Chair in Engineering Design and Compressor TechnologyHowden£100,000 per annum1 January 2008ongoing
Professor Ian SmithProfessor Nikola StosicOptimisation of low grade heat recovery systems with screw expandersHelix Power£50,000 per annum1 January 2012ongoing
Professor Ahmed KovacevicDr Nusa FainIntegration of Marketing and R&D in New Product DevelopmentHowden Compressors Ltd£170,7991 January 201131 December 2012
Professor Ahmed KovacevicDr Nusa FainBrief Encounters Network: Exploring New Forms of Online Collaborative DesignEngineering and Physical Sciences Research Council£3,5591 March 20121 July 2012
Professor Ahmed KovacevicDr Sham RaneNARIP: Networked Activities for Realisation of Innovative ProductsErasmus and Strategic partnerships€87,4201 October 201430 September 2017
Professor Ahmed KovacevicProfessor Nikola StosicGrid generation for variable screw rotor geometry - Funds for PhD research for Sham RaneMaya Engineering Works, India and City, University of London£15,000 (Maya)
£30,000 (City)
1 September 201130 September 2014
Professor Nikola StosicProfessor Ahmed KovacevicDynamic behaviour of compressor system in unsteady operation - Funds for PhD research for Ekaterina ChukanovaGreenleaves International LLC, Oregon, USA and City, University of London£15,000 (Greenleaves)
£30,000 (City)
1 September 201130 September 2014
Professor Ahmed KovacevicProfessor Manolis GavaisesMultiphase flow in the suction of screw compressorsCompressors Centre, Cavitation Centre, Overheads AK£78,0001 January 201231 December 2015
Professor Ahmed KovacevicProfessor Nikola StosicThermal management of clearances in screw compressorsHowden£5,000 fees
£28,000 through various projects
10 April 201030 September 2015
Professor Nikola StosicProfessor Jamshid NouriExperimental investigation of flow in screw compressors by LDVEPSRC£220,0001 May 200531 May 2005
Professor Ahmed Kovacevic Multiphase pumping systemsDASS Motors, Canada£55,0001 May 20071 May 2008

Projects

“N” rotor profile

The City “N” profile has been developed as a result of 30 years' research and development in screw compressor technology and world patents are held on it.  It confers the following advantages over other profiles:

  • Greater flow area for a given rotor diameter
  • Smaller leakage area
  • Stronger gate rotor lobes, which reduces lobe deflection both during manufacture and operation
  • Involute form on the contact band, leading to nearly pure rolling relative motion between rotors
  • Lower rotor contact forces without the risk of “rotor rattle” through local torque reversal
  • Avoiding seizure in the event of rotor direct contact.

Diagram showing the N rotor profile

"N" rotor profile diagram. View full-size image.

Expanders

Two phase process lubricated expander on test rig

Two-phase process lubricated screw expander on test rig. View full-size image.

Expanders have a variety of applications but for positive displacement machines, their biggest potential is for two-phase processes where they may be used to replace throttle valves and for large scale power recovery from low grade heat sources.

The centre holds vital patents on the use of any type of positive displacement machine for this purpose and has developed low cost, process lubricated twin-screw expanders with adiabatic efficiencies greater than 75%; the highest value ever attained in a two-phase expansion process.

Machine design

Given the required performance data, the centre offers full design services either for a complete compressor or expander, or for rotor and porting only, given the details of the machine.  The output is then delivered to the customer in the form of drawings, which are also accessible electronically from a secure site.

The centre is also able to arrange prototype manufacture and has test facilities complying with full international standards for the testing of air and refrigeration compressors.

Machine design diagram example

SCORPATH

The centre has developed an extensive range of software to aid the design of compressors, which is continually being upgraded.  The main package is known as SCORPATH (Screw Compressor Optimum Rotor Profile and THermodynamics).  Starting from the specified compressor duty and the minimum number of assumptions, this  program determines the optimum machine geometry and rotor profile to obtain the desired results.  The output includes full details of the rotors and their porting which can be imported directly into a CAD system, together with performance predictions, bearing loads and suggested choice and details of the tool profile required to manufacture the rotors.  User licences are available for this package.

Screenshot from the SCORPATH software

Screenshot from the SCORPATH software. View full-size image.

Download the software

Computational Fluid Dynamics and Analysis

Computational Fluid Dynamics (CFD) is widely used today as an aid for optimising the design of fluid machinery.  However, due to the complexity of the geometry and other associated problems, this analytical tool was not used for screw compressors.

The centre has developed SCORG (Screw Compressor Rotor Geometry), a grid generator, together with associated supporting functions, which enables screw compressor flow and performance to be estimated when attached to commercial CFD and CCM (Computational Continuum Mechanics) solvers.  In the latter case, solid-fluid interactions can be estimated so that component distortion and its effect on compressor or expander performance can be estimated.

As in the case of SCORPATH, user licences are available for this software package.

SCORG software screenshot

Screenshot from the SCORG software. View full-size image.

Download the software

Use within industry

Reference list of major industrial users of the centre's research, advisory and design services:

CompanyCity / StateCountry
AC CompressorsAppletonUnited States of America (USA)
AerzenerAerzenGermany
AgroholodmashIzhevskRussia
AirplusInchoonKorea
ArsenalSt PetersburyRussia
AtmosCharstCzech Republic
AvtovazTogliattiRussia
Azti TecnaliaSukarrietaSpain
BitzerSingelfingenGermany
CarrierSyracuse, New YorkUSA
CFXBerlinGermany
CMP CorpOklahoma City, OklahomaUSA
ComotiBucharestRomania
Dalian RefrigerationDalianChina
DassEdmontonCanada
Dresser-RandWakefieldUnited Kingdom (UK)
Drum InternationalBradfordUK
Dunham BushHavantUK
Duynie Holding BV The Netherlands
DV SystemsBarrie, OntarioCanada
Eaton CompressorsClayton, OklahomaUSA
ElectrathermRenoUSA
ElgiCoimbatoreIndia
ElthomNicosiaCyprus
Fairchild ControlsFrederick, MarylandUSA
FrascoldMilanItaly
Frick-IndiaNew DelhiIndia
Gardner DenverQuincy, IllinoisUSA
GE Global ResearchMunichGermany
GeodynamicsBrisbaneAustralia
GHH (IRCO)OberhausenGermany
GoodrichBirminghamUK
HelixEast KilbrideUK
HolroydMilnrowUK
HowdenGlasgowUK
Jaecklin Gebr GmbHAugsburgGermany
JYCSeoulSouth Korea
Knorr-BremseSirenFrance
KomsanIstanbulTurkey
Korea Inst Research South Korea
Magnum PowersOregonUSA
Mahle Powertrain UK
Mainstream EngineeringRockledge, FloridaUSA
Mayekawa (MYCOM)TokyoJapan
Measuring SpecialitiesHamptonUSA
Ormat TurbinesYavneIsrael
Pars Iran
Powertrain LtdShorehamUK
QinetiQFarnboroughUK
RefcompMilanItaly
Rolls RoyceIndianapolis, IndianaUSA
Rotary Compressor Systems Switzerland
RotorcompMunichGermany
ShellThorntonUK
Svenska Rotor Maskiner (SRM)StockholmSweden
Tamrotor (GD)TampereFinland
TDIAarhusDenmark
TermomeccaniaLa SpezziaItaly
Trane (IRCO)La Crosse, WisconsinUSA
TrudbenikDobojBosnia and Herzegovina
TutthillSpringfield, MontanaUSA
VmacNanaimoCanada
VMC ItaliaCreazzoItaly
WhippleSacramentoUSA
Wilksch AirmotiveBuckinghamUK
Wittig (GD)SchopfheimGermany
WuxiWuxiChina

Portrait of Nikola Stosic

Professor Nikola Stosic

People

Core members

Current PhD students

  • Nausheen Basha
  • Suraj Abdan
  • Mr Mohammad Arjeneh
  • Mr David Buckney
  • Ms Bhagya Lakshmi
  • Ms Israt Rumana Kabir
  • Mr Abdullah Qaban

Past PhD students

  • Ms Ekaterina Chukanova
  • Georges  Karagiorgios
  • Sasa Zagorac
  • Ahmed Kovacevic
  • Kupachi Venu Madhav
  • Elvedin Mujic
  • Diego Guerrato
  • Anegar Panesar
  • Chima Okezue
  • Sham Rane
  • Madhulika Kethidi
  • Evans Chikarakara
  • Syrifa Nur Aqida
  • Abdal Tamtam
  • Asnul Ahmed

Visiting scholars

  • I. McCimmie, Research Assistant
  • K. VenuMadhav, Elgi India, Visiting Research Fellow
  • Professor L Li, Xi’an Jaotang University, China, Visiting Research Fellow
  • Professor V. Supin, Xi’an Jaotang University, China, Visiting Research Fellow
  • Dr Xuyuan Peng, Xi’an Jaotang University, China, Visiting Research Fellow
  • Dr G. H. Lee, Doowon University, Korea, Visiting Research Fellow
  • Mr W M Zhang, Dalian Refrigeration China, Visiting Research Fellow
  • Mr J Liu, Dalian Refrigeration China, Visiting Research Fellow
  • Mr J Z Chen, Dalian Refrigeration China, Visiting Research Fellow
  • Mr J. M. Sun, Dalian Refrigeration China, Visiting Research Fellow
  • Mr A. D. Carlsson, KTH, Sweden, Research Student
  • Mr A Topcic, Research Engineer
  • Mr Ming, JYC, China, Compressor Engineer
  • Mr Xiajun Wu, Wuxi, China, Compressor Engineer
  • Mr G Greenough, DVSystems, Canada, Compressor Engineer
  • Dr Hyungki Shin, Senior Researcher, Korean Institute of Energy
  • Mr G Stupple, Jaecklin, Germany
  • Mr D Faksa, VSB – Technical University of Ostrava, Czech Republic
  • Mr Yan Di, State Key Laboratory of Mechanical Transmission, Chongqing University, China
  • Dr. Danqing Yin
  • Professor Fahmida Gulshan
  • Professor ASAW Kurney

Associate members of academic staff

Events

10th International Conference on Compressors and their Systems
11th-13th September 2017

Short Course on Computational Fluid Dynamics in Rotary Positive Displacement Machines
9th-10th September 2017, City, University of London

Tooth Profile Design and Numerical Modelling of Twin-screw Pumps Based on CFD
10th May 2016, 1.45pm, Northampton Suite C, Northampton Building, City, University of London

Recent events

Progress in Sliding Vane Rotary Technology
20th January 2016, 1.00pm, Room AG04, College Building, City, University of London

Theory of Hydrostatic Machines and Hydrostatic Power Drives
28th January 2016, 3.00pm, Room C316, Tait Building, City, University of London

9th International Conference on Compressors and their Systems
7th-9th September 2015, Mermaid Conference Centre

20th Anniversary of the Centre for Positive Displacement Compressors Technology
6th September 2015, City, University of London

Research seminars

18th May 2015, R202, Franklin Building – City, University of London

20th April 2015, Northampton Suite A, City, University of London

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Guerrato D, Nouri J M, Stosic N, Kovacevic A and Arcoumanis C, 2008: 'Flow Development through the Discharge Chamber of a Screw Compressor', Proc. IMechE, Part E: J. Process Mechanical Engineering, 2008, 222(E4), 211-223

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Kovacevic A, Stosic N. and Smith I.K, 2002: 'Numerical Simulation of Fluid Flow and Solid Structure in Screw Compressors', Proceedings of 2002 ASME Congress, Symposium on the Analysis and Applications of Heat Pump and Refrigeration Systems, New Orleans, LA, November 17-22, 2002. Download the paper (pdf)

Kovacevic A, Mujic E, Stosic N, Smith I.K, 2003: 'Advanced Design Tools for Screw Compressors', 2nd DAAAM International Conference on Advanced Technologies for Developing  Countries - ATDC'03 June 25-28, Tuzla, Bosnia and Herzegovina, 2003

Kovacevic A, Stosic N, Smith I.K, 2003: 'The Application of CFD Analysis to the Design of Bifunctional Machines', IMechE International Conference on Compressors and Their Systems, London, September 8-10, 2003

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McCreath P, Stosic N, Smith I.K, Kovacevic A, 2003: 'Proektirovanie effektivniih vintoviih kompressorov dlia podachi suhogo vazduha', Compressors and Pneumatics, Vol 1 pp 2-5, 2003

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Mujic E, Kovacevic A, Stosic N, Smith I.K, 2005: 'Analysis and Measurement of Discharge Port Influence upon Screw Compressor Noise', 9th International Research/Expert Conference Trends in the Development of Machinery and Associated Technology, TMT 2005, Antalya, September 2005

Mujic E, Stosic N, Kovacevic A, Smith I.K, 2007: 'The Influence of Port Shape on Gas Pulsations in a Screw Compressor Discharge Chamber', International Conference Compressors and Their Systems, London, 2007. Download the paper (pdf)

Mujic E, Kovacevic A, Stosic N, Smith I.K, 2007: 'The Influence of the Discharge Port Shape on Screw Compressor Performance and Gas Pulsations', 2008 International Compressor Engineering Conference at Purdue, 14-17 July 2008, Purdue, USA

Mujic E, Stosic N, Kovacevic A, Smith I.K, 2008: 'Reduction of Noise in Screw Compressors', Trends in the Development of Machinery and Associated Technology, TMT 2008, Istanbul, Turkey, 26-30 August, 2008. Download the paper (pdf)

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Peng N, Xing Z, 1990: 'New Rotor Profile and its Performance Prediction of Screw Compressor', International Compressor Engineering Conference At Purdue, 18

Rinder L, 1979: Schraubenverdichter (Screw Compressors), Springer Verlag, New York

Rinder L, 1984: 'Schraubenverdichterlaufer mit Evolventenflanken (Screw Compressor Rotor with Involute Lobes)', Proc. VDI Tagung "Schraubenmaschinen 84" VDI Berichte Nr. 521 Dusseldorf

Rinder L, 1987: US Patent 4,643,654

Sakun I.A, 1960: Vintovie kompresorii (Screw Compressors), Mashinostroenie Leningrad

Sauls J, 1998: 'An Analytical Study of the Effects of Manufacturing on Screw Rotor Profiles and Rotor Pair Clearances', Proc. VDI Tagung "Schraubenmaschinen 98", Dortmund VDI Berichte 1391

Shibbie, 1979: US Patent 4,140,445

Singh P.J, Onuschak A.D, 1984: 'A Comprehensive Computerized Method For Twin Screw Rotor Profile Generation and Analysis', Purdue Compressor Technology Conference 544

Singh P.J, Schwartz J.R, 1990: 'Exact Analytical Representation of Screw Compressor Rotor Geometry', International Compressor Engineering Conference At Purdue, 925

Smith I.K, Stosic N, 1995: 'The Expressor: An Efficiency Boost to Vapour Systes by Power recovery from the Throttlong Process', Proceedings of ASME Congress, Vol 34, November 1995 75. View the paper

Smith I.K, Stosic N, Aldis C.A, 1996: 'Development of the Trilateral Flash Cycle System: Part 1: Fundamental Considerations (doc), Part 2: Increasing Power Output with Working Fluid Mixtures (doc), Part 3: The Design of High-Efficiency Two-Phase Screw Expanders (doc)', Proceedings of IMechE, Journal of Power and Energy, London, Vol 210, Part A, 75

Smith I.K, 1999: 'Review of the Development of Two-Phase Screw Expanders', Proceedings of IMechE, Conference 'Compressors and Their Systems, London, September 1999 75. View the paper

Smith I.K, Stosic N, Aldis C.A, Kovacevic A, 1999: 'Twin Screw Two-Phase Expanders in large Chiller Units', Proceedings of IMechE, Conference 'Compressors and Their Systems, London, September 1999 75. View the paper

Smith I.K, Stosic N. and Kovacevic A, 2001: 'Power Recovery From Low Cost Two-Phase Expanders', Geothermal Research Council 2001 Annual Meeting, San Diego, CA, August 2001. Download the paper (pdf)

Smith I.K, Stosic N. and Kovacevic A, 2001: 'A Feasibility Study of Throttle Loss Power Recovery in Large Heat Pums with Two-Stage Compressors',
IMechE Conference on Compressors and Their Systems, London, September 2001.

Smith I.K. and Stosic N, 2001: 'Prospects for Energy Conversion Efficiency Improvements by the Use of Two-Phase Expanders', 2nd International Heat Powered Cycles Conference, Paris, September 2001

Smith I.K, Stosic N, Kovacevic A, 2002: 'Twin Screw Machines to replace Throttle Valve in Refrigeration Systems', Strojniški Vestnik, Journal of Mechanical Engineering, 8 p 484, 2002

Smith I.K, Stosic N, Kovacevic A, 2004: 'An Improved System for Power Recovery from High Enthalpy Liquid Dominated Flows', GRC Annual Meeting, Indian Wells, California, August 2004

Smith I.K, Stosic N and Kovacevic A, 2005: 'An Improved System for Power Recovery from High Enthalpy Liquid Dominated Fields', World Geothermal Congress, Antalya Turkey, May 2005

Smith I.K, Stosic N, Kovacevic A, 2005: 'Screw Expanders Increase Output and Decrease the Cost of Geothermal Binary Power Plant Systems', GRC Annual Meeting, Reno, Nevada, September 2005. Download the paper (pdf)

Smith I.K, Stosic N, Kovacevic A, 2007: 'Cost Effective Small Scale ORC Systems for Power Recovery from Low Enthalpy Resources', GRC Annual Meeting, Reno, Nevada, September 2007. Download the paper (pdf)

Stosic N, Hanjalic K, 1977: 'Contribution towards Modelling of Two-Stage Reciprocating Compressors', Int.J.Mech.Sci. 19, 439

Stosic N, Hanjalic K, Koprivica J, Lovren N, Ivanovic M, 1986: 'CAD of Screw Compressor Elements', Strojarstvo Journal Zagreb 28, 181

Stosic N, Milutinovic Lj, Kovacevic A, Hanjalic K, 1992: 'Investigation of the Influence of Oil Injection upon the Screw Compressor Working Process', Int. J Refrig, Vol 15, 206. View the paper

Stosic N, Smith I.K, Zagorac S, 1996: 'CFD Studies of Flow in Screw and Scroll Compressors', Proc. XVIII Conference on Compressor Engineering at Purdue, 181

Stosic N., Hanjalic K., 1996: 'A General Method for Screw Compressor Profile Generation', Proc. XVIII Conference on Compressor Engineering at Purdue, 157

Stosic N, 1996: Patent Application GB 9610289.2

Stosic N, Hanjalic K, 1997: 'Development and Optimization of Screw Machines with a Simulation Model, Part I: Profile Generation', ASME Transactions, Journal of Fluids Engineering, Vol 119, p 659. View the paper

Stosic N, Smith I.K, Kovacevic A, Aldis C. A, 1997: 'The Design of a Twin-screw Compressor Based on a New Profile', Journal of Engineering Design, Vol 8, 389. View the paper

Stosic N, Smith I.K, Brasz J, Sishtla V, 1998: 'The Performance of a Screw Compressor with Involute Contact Rotors in a Low Viscosity Gas-Liquid Mixture Environment', Schraubenmaschinen '98, Dortmund, VDI Berichte 1391

Stosic N, 1998: 'On Gearing of Helical Screw Compressor Rotors', Proceedings of IMechE, Journal of Mechanical Engineering Science, London, Vol 212, Part C, 587. View the paper

Stosic N, Kovacevic A, Smith I.K, 2000: 'The CFD Analysis of a Screw Compressor Suction Flow', Proc. 2000 International Conference on Compressor Engineering at Purdue, 909

Stosic N, Smith I.K, Kovacevic A, Venumadhav K, 2000: 'Retrofit 'N' Rotors for Efficient Oil-Flooded Screw Compressors', Proc. 2000 International Conference on Compressor Engineering at Purdue, 917. Download the paper (pdf)

Stosic N, Smith I.K, and Kovacevic A, 2001: 'Rotor Interference as a Criterion in a Screw Compressors Design', ICTC, International Compressor Technique Conference, Wuxi, China, August 2001. Download the paper (pdf)

Stosic N, Smith I.K, and Kovacevic A, 2001: 'The design of efficient Screw Air Compressors', 3rd Symposium 'Revitalization and Modernization of Metal Industry in B&H, Bihac, Bosnia and Herzegovina, October 2001

Stosic N, Smith I.K, and Kovacevic A, 2002: 'A Twin Screw Combined Compressor and Expander for CO2 Refrigeration Systems', XVI International Compressor Engineering Conference at Purdue, July 2002. Download the paper (pdf)

Stosic N, Smith I.K, and Kovacevic A, 2002: 'Optimization of Screw Compressor Design', XVI International Compressor Engineering Conference at Purdue, July 2002

Stosic N, Smith I.K, and Kovacevic A, 2002: 'Optimization of Screw Compressor Design', VIII European Congress on Fluid Machinery for the Oil, Gas and Petrochemical Industry, October 2002. Download the paper (pdf)

Stosic N, Smith I.K, and Kovacevic A, 2002: 'Screw Compressor: A Strong Link in the Development Chain', 1st International Conference on Advanced Technologies for Developing Countries September 12-14, 2002 Slavonski Brod, Croatia

Stosic N, Smith I.K, Kovacevic A, 2002: 'Screw Compressor: A Strong Link in The Development Chain', Technical Gazette, Slavonski Brod, Vol 9, No 3,4, pp 41-46, 2002. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2003: 'Rotor Interference as a Criterion for Screw Compressors Design', Journal of Engineering Design, Vol 14, No 2, pp 209-220, 2003

Stosic N, Smith I.K, Kovacevic A, 2003: 'The Design of Efficient Air Screw Compressors', Mašinstvo Journal, Zenica, 7(1) pp12-26, March 2003

Stosic N, Smith I.K, Kovacevic A, 2003: 'Optimisation of Screw Compressors', Journal of Applied Thermal Engineering, 23, pp 1177-1195, 2003. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2004: 'Multifunctional Screw Machines', Mašinstvo Journal, Zenica, 8(1) pp 3-16, March 2004

Stosic N, Smith I.K, Kovacevic A, 2004: 'Opportunities for Innovation with Screw Compressors', Proceedings of IMechE, Journal of Process Mechanical Engineering, Vol 217, pp 157-170, 2003. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2003: 'Improving Refrigeration Screw Compressor Performance with Optimised Rotors', IMechE International Conference on Compressors and Their Systems, London, September 8-10, 2003

Stosic N, Smith I.K, Kovacevic A, 2003: 'Combined Screw Compressor-Expander in Fuel Cell Application', IMechE International Conference on Compressors and Their Systems, London, September 8-10, 2003

Stosic N, Smith I.K, Kovacevic A, 2003: 'Multifunctional Screw Compressor Rotors', ICCR the 4th International Conference on Compressors and Refrigeration, Xi’an October 21-25, 2003. Download the paper (pdf)

Stosic N, 2004: 'Screw Compressors in Refrigeration and Air Conditioning', Int Journal of HVACR Research, 10(3) pp 233-263, July 2004. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2004: 'Combined Compressor-Expander in Fuel Cell Application', COBEM 2003, 17th International Congress of Mechanical Engineers, Sao Paulo, November 10-14, 2003. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2004: 'Identification of Heat Transfer on Screw Compressor Rotors as Tool for Their Design', HEFAT 2004, 3rd International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics 21-24 June 2004, Cape Town, South Africa

Stosic N, Smith I.K, Kovacevic A, 2004: 'Extension of Operating Range of Dry Screw Compressors by Cooling of Their Rotors', 17th International Compressor Engineering Conference at Purdue, July 2004

Stosic N, 2005: 'Tool Wear and Its Compensation in Screw Rotor Manufacturing', ACAM 2005, Australasian Congress on Applied Mechanics, 16-18 February 2005 Melbourne, Victoria, Australia. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2005: Screw Compressors: Mathematical Modeling and Performance Calculation, Monograph, Springer Verlag, Berlin, June 2005, ISBN: 3-540-24275-9. Purchase the monograph

Stosic N, 2005: 'Identification of Constraints in the Optimal Generation of Screw Compressor Rotors by the Pressure Angle Method', IMechE International Conference on Compressors and Their Systems, London, September 5-7, 2005. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, Jung-uk K, Park J, 2005: 'Improving screw compressor performance', IMechE International Conference on Compressors and Their Systems, London, September 5-7, 2005. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A, 2005: 'Numerical Investigation of Heat Transfer on Screw Compressor Rotors', 8th Argentinian Congress on Computational Mechanics, Buenos Aires, Argentina, November 2005. Download the paper (pdf)

Stosic N, Smith I.K, Kovacevic A and Zhang W M, 2005: 'An Investigation of Liquid Injection in Refrigeration Screw Compressors', ICCR the 5th International Conference on Compressors and Refrigeration, Dalian, July 2005

Stosic N, Mujic E, Kovacevic A, Smith I.K, 2006: 'The Influence of Discharge Ports on Rotor Contact in Screw Compressors', 18th International Compressor Engineering Conference at Purdue, July 2006. Download the paper (pdf)

Stosic N, 2006: 'Increasing the Reliability of Screw Compressors in the Gas and Process Industries', Oil & Gas Processing Review, London 2006. Download the paper (pdf)

Stosic N, 2006: 'A geometric approach to calculating tool wear in screw rotor machining', International Journal of Machine Tools & Manufacture 46, 1961–1965

Stosic N, 2006: 'Evaluating errors in screw rotor machining by tool to rotor transformation', Proc. IMechE Vol. 220, Part B: J. Engineering Manufacture, pp 1589-1596

Stosic N, Kovacevic A, Mujic E, Smith I.K, 2006: 'Vacuum and Multiphase Screw Pump Rotor Profiles and Their Calculation Models', Schraubencompressortagung, Dortmund, VDI Berichte 1932, September 2006

Stosic N, Broglia T and Iobbi M, 2006: 'Improving the Capacity and Performance of Air-Conditioning Screw Compressors', IMECE 2006, ASME Congress, Chicago, November 2006. Download the paper (pdf)

Stosic N, Kovacevic A, Mujic E, Smith I.K, 2007: 'Development of a Rotor Profile for Silent Screw Compressor Operation', International Conference Compressors and Their Systems, London, 2007. Download the paper (pdf)

Stosic N, Kovacevic A, Mujic E, Smith I.K, 2007: 'An Evaluation of Encapsulated Oil Flooded Screw Compressor Systems', IMECE2007, ASME Congress, Seattle, November 2007. Download the paper (pdf)

Stosic N, Mujic E, Kovacevic A, Smith I.K, 2008: 'Profiling of Screw Compressor Rotors by Use of Direct Digital Simulation', International Compressor Engineering Conference at Purdue, July 2008. Download the paper (pdf)

Stosic N, Smith I.K, Mujic E, Kovacevic A, 2008: 'Geometry of Screw Compressor Rotors and Their Tools', ICCR 2008, International Conference on Compressor and Refrigeration, Xian, September 2008. Download the paper (pdf)

Stosic N and Smith I.K, 2008: 'Utilization of Expansion Work in Transcritical CO2 Heat Pumps in Combined Heating and Cooling', Proceedings of IMECE2008, 2008 ASME International Mechanical Engineering Congress and Exposition, Boston, USA, November 2-6, 2008,

Venu Madhav K, Stosic N, Smith I.K, and Kovacevic A, 2001: 'The Design of a Family of Screw Compressors for Oil–Flooded Operation', IMechE Conference on Compressors and Their Systems, London, September 2001. Download the paper (pdf)

Venu Madhav K, Stosic N, Smith I.K, Kovacevic A, 2003: Proektirovanie semeistva maslozapolneniih vintoviih kompressorov Compressors and Pneumatics, Vol 1 pp 2-5, 2003

Tang Y, Fleming J.S, 1992: 'Obtaining the Optimum Geometrical Parameters of a Refrigeration Helical Screw Compressor', International Compressor Engineering Conference at Purdue 213

Tang Y, Fleming J. S, 1994: 'Clearances between the Rotors of Helical Screw Compressors: Their determination, Optimization and Thermodynamic Consequences', Proceedings of IMechE, Journal of Process Mechanical Engineering, Vol 208, 155

Tang Y. and Fleming J. S, 1994: 'Obtaining the Optimum Geometrical Parameters of a Refrigeration Helical Screw Compressor', XI International Compressor Engineering Conference at Purdue, July 1992, pp 221-227

Xion Z. Dagang X, 1986: 'Study on Actual Profile Surface and Engaging Clearance of Screw Compressor Rotors', Purdue Compressor Technology Conference 239

Xing Z. W, 2000: Screw Compressors, Machine Press, Beijing

Zhang L, Hamilton J.F, 1992: 'Main Geometric Characteristics of the Twin Screw Compressor', International Compressor Engineering Conference at Purdue 213

Zhang W, Wang Z, Stosic N, Mujic E, Kovacevic A, Smith I.K, 2006: 'New Design and Rotor Retrofit to Improve Capacity and Performance of Refrigeration Screw Compressors', 18th International Compressor Engineering Conference at Purdue, July 2006. Download the paper (pdf)

  • Professor Ahmed Kovacevic t: +44 (0)20 7040 8780
    Northampton Square London EC1V 0HB

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