Mayank Modak

An experimental investigation on heat transfer enhancement in circular jet impingement on hot surfaces by using Al2O3/water nano-fluids and aqueous high-alcohol surfactant solution

ABSTRACT The present article reports the heat transfer characteristics of a vertical stainless steel foil of 0.15 mm thickness (SS304) by circular impinging jets of various fluids such as pure water, nano-fluids (Al2O3-water, ф = 0.15%, 0.6%), and aqueous high-alcohol surfactant (HAS, i.e., 2-ethyl-hexanol, 100–400 ppm) studied using an infrared thermal imaging camera (A655sc, FLIR System). The enhancement in the heat transfer rates for Al2O3-water nano-fluids with ф = 0.15%, ф = 0.60%, and aqueous surfactant solution (150ppm) is found to be 140%, 207%, and 117% higher compared to pure water results, respectively. The surface characteristics of the foil after jet impingement by various fluids are also studied using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and surface wettability.

Heat Transfer Characteristics of Hot Surface Using High Alcohol Surfactant by Impinging Liquid Jet

In the present study, an experimental investigation has been carried out to analyze the effect of surfactant on heat transfer characteristics of a circular impinging liquid jet. A rectangular stainless steel foil (AISI-304, 0.15 mm thick), used as the target surface, was electrically heated to obtain the required initial temperature. A single-phase circular water jet of diameter 1.38 mm is allowed to impinge on the hot surface. Thermal images of the target surface during liquid jet impingement were recorded by using an infrared camera (A655sc, FLIR System) positioned on the side of the target surface opposite to the impinging nozzle. The distribution of heat flux on the target surface is evaluated from the recorded thermal images during transient cooling. Tests were performed for an initial surface temperature of 500 °C, Reynolds number (8893 ≤ Re ≤ 12847) and nozzle to plate distance was l/d = 2.5. Experiments have been performed using 2-Ethyl Hexanol added water solution at different concentration (0–400 ppm). Surface heat flux distribution during transient cooling of hot surface is obtained. It was observed that the surface heat flux increases with the rise in the jet Reynolds number and achieves its maximum at surfactant concentration of 200 ppm at stagnation point (6.2 MW/m2 at Re = 8893 to 6.5 MW/m2 at Re = 12847; 200 ppm).

An Experimental Investigation to Analyse the Heat Transfer Characteristics of Hot Surface by Obliquely Impinging Liquid Jet

In the present study, an experimental investigation has been carried out to analyze the effect of jet inclination on the heat transfer characteristics of a vertical hot surface during circular free impinging liquid jet. A rectangular stainless steel foil (AISI-304, 0.15 mm thick), used as the target surface, was electrically heated to an initial temperature of 400 °C. A single-phase circular water jet of diameter 1.38 mm is allowed to impinge on the hot surface. Infrared thermal camera (A655sc, FLIR System) is used to record the thermal images of the target surface during liquid jet impingement. The distribution of heat flux on the target surface is evaluated from the thermal images, recorded during transient cooling experiments. Tests were performed for an initial surface temperature of 400 °C, Reynolds number \(\left( {8893 \le Re \le 12847} \right)\), and nozzle to plate distance \(\left( {2.5 \le l/d \le 4.5} \right)\) and jet inclination (0 ≤ α ≤ 45°). The heat flux is found to be maximum at stagnation point for the jet inclination of 30°. It is observed that the jet to plate spacing has minimal effect of stagnation point maximum heat flux.

Heat Transfer Characteristics of CuO-Water Nanofluids Jet Impingement on a Hot Surface

In present study, an experimental investigation has been carried out to analyze the heat transfer characteristics of CuO-water nanofluids jets on a hot surface. A rectangular stainless steel foil (AISI-304, 0.15 mm thick) is used as a test surface is electrically heated to obtain the required initial temperature. The distribution of heat flux on the target surface is evaluated from the recorded thermal images during transient cooling. The effect of nanoparticle concentration and Reynolds number of the nanofluids jet impingement heat transfer characteristics is studied. Tests were performed for an initial surface temperature of 500°C, Reynolds number (5000≤Re≤13000), CuO-water nanofluids concentration (Φ= 0.15%, 0.6%) and nozzle to plate distance was l/d= 4.Copyright

Experimental Study on Heat Transfer Characteristics of Circular Jet Impingement Boiling on the Variety of Structured Copper Surfaces in Stagnation Zone

In the present work an attempt has been made to study the heat transfer characteristics of single circular jet on a variety of enhanced surfaces. In the present investigation three different copper target surfaces of various surface modifications: bare copper surface, pin fin enhancement surface and a flat surface coated with alumina porous layer. The heat transfer performance of each surface is studied in two phase boiling operation at different flow rates (3959 < Re < 7900). The comparison indicates that both the surface modification have enhanced the boiling heat transfer rates.Copyright