Heat transfer of flow boiling carbon dioxide in vertical upward direction. (1st November 2022)

• Record Type: Journal Article
• Authors: Schmid, David; Verlaat, Bart; Petagna, Paolo; Revellin, Rémi; Schiffmann, Jürg
• Is Part Of: International journal of heat and mass transfer. Volume 196(2022)
• Publication Date: 2022-11-01
• Subjects: Carbon dioxide (CO2) -- Heat transfer -- Vertical two-phase upflow -- Detector cooling in high energy physics -- Evaporative cooling -- Flow boiling -- R744; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2022.123246
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Heat transfer measurements of flow boiling CO2 in 8 mm tubes in vertical upward direction. A correlation to predict the dryout inception within the experimental domain is proposed. Comparison of more than 1900 experimental data points to existing prediction models. Heat transfer properties of CO2 are enhanced in vertical upflow compared to horizontal data. A vertical multiplier is suggested to capture the trends with two existing prediction models. Abstract: Heat transfer measurements of flow boiling Carbon Dioxide (CO2) in vertical upward direction have been carried out with a dedicated test facility at the European Organization for Nuclear Research (CERN). The investigation covers saturation temperatures within a range of − 25 ∘ C ≤ T sat ≤ + 5 ∘ C, mass velocities from 100 kg m − 2 s − 1 ≤ G ≤ 450 kg m − 2 s − 1 and heat fluxes of 5.3 kW m − 2 and 11.4 kW m − 2 . The experiments have been conducted in a vertical upward evaporator of 8 mm inner diameter and 8 m length and a database of more than 1900 measurements has been compiled within the present study. The heat transfer mechanism is dominated by the nucleate boiling contribution and dryout is observed as a function of saturation temperature, mass velocity and heat flux. A correlation is proposed to predict the dryout inception within the experimental range where the onset of dryout has been observed. The results suggest that most commonly used heat transfer prediction models underpredict the heat transfer mechanisms of CO2 . Moreover, the heat transfer coefficients of CO2 increase in vertical upward direction, compared to the data of horizontal studies. For that reason, a vertical multiplier is suggested to capture the trends of vertical upflow with two existing prediction models.