Media flow analysis of single-channel pre-mixed liquid CO2 and MQL in sustainable machining

Grguraš, Damir (author), Sterle, Luka (author), Malneršič, Aleš (author), Kastelic, Luka (author), Courbon, Cedric (author), Pušavec, Franci (author)

Single-channel supply of pre-mixed liquid carbon dioxide (LCO2) and minimum quantity lubrication (MQL) represents a state-of-the-art LCO2 assisted machining. However, to fully understand and optimize cooling and lubrication provided by the LCO2 + MQL, a fundamental media flow analysis is essential, yet not researched enough. Therefore, in this paper, media flow velocity and oil droplet size were analysed in supplying line and at the nozzle outlet using high-speed camera and proprietary single-channel system. Results indicate that pre-mixed media flow velocity is mainly influenced by the LCO2 expansion rate upon the nozzle outlet, wherein oil droplet size is largely dependent on the solubility between oil and LCO2. Media flow velocity increases significantly from an average of 40 m/s in the supplying line to the excess of 90 m/s at the nozzle outlet due to the pressure drop and LCO2 expansion. Furthermore, this volume expansion causes the oil droplet to increase to the point of critical, unstable droplet size. Afterward, the unstable oil droplet breaks up into smaller oil droplets. It was found, that nonpolar oil, with greater solubility in LCO2, compared to the polar oil, provides droplets as small as 2 [micro]m in diameter. Smaller oil droplets positively reflect on tool wear and tool life in LCO2 assisted machining, as the longest tool life was achieved by using the nonpolar oil for pre-mixed LCO2 + MQL

• Language: English
• Keywords: flow analysis, flow velocity, droplet size, single-channel supply, liquid carbon dioxide - LCO2, minimum quantity lubrication - MQL, LCO2 assisted machining
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: Str. 3-10
• Numbering: Vol. 67, no. 1/2
• PID: 20.500.12556/RUL-125728
• UDC: 621.9(045)
• ISSN on article: 0039-2480
• DOI: 10.5545/sv-jme.2020.7076
• COBISS.SI-ID: 54067971
• Publication date in RUL: 06.04.2021

Record is a part of a journal

• Title: Strojniški vestnik
• Shortened title: Stroj. vestn.
• Publisher: Zveza strojnih inženirjev in tehnikov Slovenije [etc.], = Association of Mechanical Engineers and Technicians of Slovenia [etc.
• ISSN: 0039-2480
• COBISS.SI-ID: 762116

Secondary language

• Language: Slovenian
• Title: Analiza pretoka enokanalne mešanice kapljevitega CO2 in MQL pri trajnostnem odrezavanju
• Keywords: analiza pretoka, hitrsot pretoka, velikost kapljic, enokanalni dovod, kapljeviti ogljikov dioksid, oljna megla, LCO2 podprto odrezavanje

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: L2-8184
• Name: Razvoj in implementacija kriogenega odrezavanja v serijsko proizvodno za povečanje produktivnosti procesov vrtanja in frezanja

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0266
• Name: Napredne izdelovalne tehnologije za visoko kakovostno in trajnostno proizvodnjo