Experimental Study on Influence of Nanoparticles and Nanobubbles in Heat Transfer Applications

Abstract

The current research focus is to understand that the heat transfer newlinemechanism with nanofluids not only depend on the nanoparticles characteristics newlinesuch as thermal conductivity, particle size, length to diameter ratio, purity, newlineshape and agglomeration issues. Then the main theme is to address that the newlinequality of heat transfer fluid is also equally important to improve the thermo newlinephysical properties of nanofluids. Here, de ionized water is subjected to newlinenanobubble generation by hydrodynamic cavitation process prior to heat newlinetransfer studies to remove the surface impurities below detection limit. The high newlineLaplace pressure developed due to injection of gas in liquid is sufficient enough newlineto break down the organic pollutants present in heat transfer fluid. The dynamic newlinelight scattering measurement on particle size distribution was performed for newlineevery 10 minutes of nanobubbles generation. newlineFurther, two different kinds of nanoparticles such as MWCNT and MgO newlinewere mixed with the nanobubbled water to examine the temperature and volume newlineconcentration influence on thermal conductivity of the water. In addition, the newlineCuO nanoparticles added with MWCNT/water and MgO/water also contributed newlinesignificant improvement in thermal conductivity. The experimental work was newlinecarried out at two different temperatures such as 30 ºC and 40 ºC. The hybrid newlinenanofluids such as MWCNT/water and MgO/water and the dihybrid nanofluids newlinenamely CuO- MWCNT/water and CuO-MgO/water were prepared at maximum newlinevolume concentration of 1%. Since three different nanoparticles are employed newlineto prepare all the nanofluid combination, the two-step process of nanofluid newlinegeneration was utilized. The isothermal condition was monitored periodically newlineby a thermostat to avoid heating of nanofluid during generation. newlineThe CuO- MWCNT/water nanofluid depicted 12.1% and 14.2% thermal newlineconductivity augmentation at 30 ºC and 40 ºC respectively. The CuOMgO/ newlinewater nanofluid outcome that 13.6% and 16.1% thermal conductivity newlinevi newlineaugmentation at 30 ºC and 40 ºC respectively.