![Sample our Economics, Finance,Business & Industry journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5931/TOC-Subject-Sample-2021-Economics-Finance-Business-Industry.jpg"})
ABSTRACT
Present study reports the nucleate pool boiling characteristics of micro structured copper surface developed by utilizing two different laser systems, namely, pulsed Nd:YAG laser and continuous wave laser. Tests are conducted at atmospheric pressure and saturation temperature by using water as pool liquid. Enhancement in heat transfer coefficients was observed over all laser processed surfaces. The maximum enhancement in heat transfer coefficient was found to be 136% and 93% for the micro structured surfaces developed by using continuous wave and pulsed laser, respectively, compared to the reference smooth surface. The enhancement in heat transfer performance of micro structured surfaces are due to the presence of surface pores, grooves and micro cavities generated due to laser melting process.
Acknowledgments
The authors would like to thank Dr I. A. Palani, Mr Akash K., Mr Mani, Mr Abhinav from Mechatronics and Instrumentation Laboratory, Indian Institute of Technology Indore, for their valuable support in the development test surfaces by using continuous wave and nanosecond pulsed lasers. Authors are thankful to Sophisticated Instrument Centre of Indian Institute of Technology Indore, for Field-Emission Scanning Electron Microscope (FE-SEM), Supra55 Zeiss.
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 |
| qʺ | = | 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 |