Fabrication of Cu@G composite coatings and their pool boiling performance with R-134a and R-1234yf

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ABSTRACT

The present work explores the pool-boiling performance of refrigerants (R-134 and R-1234yf) on the plain Cu and graphene nanoplatelets (G) reinforced Cu matrix (Cu@G) composite coated heating surface. A two-step electrodeposition technique was employed to prepare microporous Cu@G composite coatings. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) studies confirmed the successful fabrication of microporous structure of Cu@G composite coatings. Surface profilometer investigation was done to know the surface roughness of prepared Cu@G composite coatings. Pool boiling experiments were carried out with increasing heat flux from 8.80 kW/m² to 61.25 kW/m² at a saturation temperature of 10°C. Test results of R-134 and R-1234yf were compared. The experimental results revealed that the heat transfer coefficients (HTCs) of R-134a were higher than R-1234yf for plain Cu and Cu@G composite coated heating surfaces.

KEYWORDS:

• SEM
• EDS
• surface roughness
• heat transfer
• R-134a
• R-1234yf

Nomenclature

$A$Area, [m²]

$Q$Power input, [W]

$I$Current, [A]

$V$Voltage, [V]

$h$Heat transfer coefficient, [W/m².K]

$K$Thermal conductivity, [W/m.K]

$T$Temperature, [K]

$M$Molecular weight, [g/mol]

$q$Heat flux, [W/m²]

$P$Pressure, [kPa]

$h_l$Latent heat, [KJ/kg]

$C_p$Specific heat, [KJ/Kg.K]

$GWP$Global warming potential

Greek symbols

$\rho$Density, [Kg/m³]

$\mathrm{\Delta }$Difference

$\vartheta$Kinematic viscosity, [m²/s]

$\sigma$Surface tension, [N/m]

Subscripts

$s$Surface

$l$Liquid

$v$Vapor

$sat$Saturation

Acknowledgments

This work was conducted in the DST- FIST (SR/FST/ETI- 391/2015(c)) sponsored Phase Change Heat Transfer Laboratory under the Mechanical Engineering Department in the National Institute of Technology Agartala (NIT Agartala), India.

Disclosure statement

No potential conflict of interest was reported by the author(s).