Significance of surface modification on nucleate pool boiling heat transfer characteristics of refrigerant R-141b. (May 2021)

• Record Type: Journal Article
• Authors: Deb, Sandipan; Das, Mantu; Das, Dipak Chandra; Pal, Sagnik; Das, Ajoy Kumar; Das, Ranjan
• Is Part Of: International journal of heat and mass transfer. Volume 170(2021)
• Publication Date: 2021-05
• Subjects: Surface modification -- Nanocoating -- Refrigerant R-141b -- Nucleate pool boiling -- Heat transfer coefficient; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2021.120994
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: The Sol-Gel method followed by spin coater was used to fabricate the copper heating surface with TF. Refrigerant R141b was used as a working fluid and heat transfer coefficient was investigated based on saturation temperature or pressure and heat flux. Experimental results were validated with established correlations and qualified with excellent agreement. A mathematical model was formulated, and it predicts the optimal heat transfer coefficient for various coating thicknesses under the nucleate pool boiling configuration. Abstract: Experimental investigations were conducted to study the significance of surface modification on the heat transport phenomena under nucleate pool boiling configuration of saturated R-141b at ambient condition over SiO2 thin film (TF) nanocoated surfaces. The experiments were conducted within the heat flux variation of 50 to 185 kW/m 2 at an interval of 15 kW/m 2 . The diameter of the heating surface was 9 mm, and the thickness was 3 mm. Five Cu heating surfaces of circular shape having zero (Emery polished surface (S1)), 125 (S2), 250 (S3), 375 (S4), and 500 (S5) nm coating thicknesses were fabricated employing the Sol-Gel approach accompanied by spin coater and characterized by surface profilometer and field emission scanning electron microscopy (FE-SEM). The current experimental results were verified with the existing correlations proposed in the literature. It was found that the heat transfer coefficient increased with an increase in the heat flux, and it is also witnessed here that modification in the surface significantly contribute towards the improvement in the heat transfer coefficient. The maximum and the minimum heat transfer were revealed at 375 (S4) and 500 (S5) nm coating thickness, respectively. Modification of the surface leads to an increase in the heat transfer coefficient due to the existence of a large number of dynamic nucleation sites. Finally, a mathematical model to predict the optimum nucleate pool boiling heat transfer coefficients for different coating thicknesses was proposed which reflects the effects of surface thickness, coating thickness, and the imposed heat flux. The model predicts good agreement with the experiment of R-141b and other existing findings within an accuracy of ± 5 %.