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ABSTRACT
The present paper reports the experimental investigation of pool boiling heat transfer on multiscale functionalized copper surfaces. Multiscale functionalized surfaces are fabricated by employing the nano-second laser surface process (NLSP) technique. The heat transfer coefficients (HTCs) of functionalized surfaces are estimated experimentally by using water and acetone as pool liquid. Tests are performed at atmospheric pressure, and saturated pool boiling condition with heat flux varyies between 0 and 330 kW/m2. The maximum HTCs for functionalized surface and reference polished surface were found to be 41,500 W/m2K and 23,000 W/m2K, respectively, with water and 22,000 W/m2K and 14,000 W/m2K, respectively, with acetone.
Nomenclature
| Cpl | = | Specific heat of liquid, J/kg-K |
| Csf | = | Surface liquid parameter used in Rohsenow correlation |
| dcyl | = | Diameter of copper block, m |
| g | = | Acceleration due to gravity, m/s2 |
| h | = | Heat transfer coefficient, W/m2 -K |
| hlg | = | Latent heat of vaporization, J/Kg |
| I | = | Corresponding current value across heater terminals, Amp |
| k | = | Thermal conductivity of copper, W/m-K |
| kl | = | Thermal conductivity of liquid, W/m-K |
| m,n | = | Empirical constants used in Rohsenow correlation |
| q’’ | = | Heat flux, W/m2 |
| T | = | Temperature recorded by thermocouple in test surface, K |
| Ts | = | Surface temperature, K |
| Tsat | = | Saturation temperature |
| V | = | Voltage applied across heater terminals, Volt |
| ∆T | = | Wall superheat, K |
| ∆x | = | Distance of thermocouple hole in test surface from top, m |
Greek Symbols
| μl | = | Liquid dynamic viscosity, Pa-s |
| ρg | = | Density of vapor, kg/m3 |
| ρl | = | Density of liquid, kg/m3 |
| σ | = | Surface tension, N/m |
Acknowledgments
The authors would like to thank Dr. I. A. Palani and PhD student Mr. Akash K. of Mechatronics and Instrumentation Laboratory, Indian Institute of Technology, Indore, for their valuable support in the development of multiscale functionalized surfaces by using Nd:YAG laser. The authors are thankful to Sophisticated Instrument Centre of Indian Institute of Technology, Indore, for Field- Emission Scanning Electron Microscope (FE-SEM), Supra55 Zeiss. Also, the authors are thankful Dr. M. P. Joshi and Dr. Raj Mohan of RRCAT, Indore, for Holmarc contact angle meter.