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The structure and soot surface growth properties of round laminar jet diffusion flames were studied experimentally. Measurements were made along the axes of ethylene-, propylene- traversedthe flames when moving to-and-fromthe flame axeswasestablished in two ways: (1) sampling in the region prior to the onsetof soot formation along the axesof the flames (but where there was a well-developedannularsoot-containingregion nearthe edge of the region exhibiting yellow soot luminosity) properly indicatedthat no soot aggregates, that could have beendepositedas the samplerpassedthrough the annularsoot-containingregion, werepresent on the samplerfor the samplingconditionsusedduring the presentstudy, and (2) the sampled sootexhibitedonly nearly constant primary sootparticle diameters at eachflame conditionalong the axis (e.g., the standarddeviationsof primary particle diameterswere lessthan 10%)rather than the widely-varying primary soot particle diametersthat would be observedif off-axis soot particles were present in the sample. The experimental uncertainties(95% confidence) of primary particlediametersat a pointwereestimatedto be lessthan10%.Streamwisegas velocities were measuredusing laser velocimetry. The experimental uncertainties(95%confidence)of thesemeasurements werelessthan5%. Fig. 1 is that after an initial rapid increase of primary soot particle diameters, just after the onset of soot formation along the axis of the flames, mean primary soot particle diameters subsequently decrease with increasing distance from the burner exit in spite of effects of soot surface growth throughout the remainder of the soot formation region. This behavior has been observed for all the laminar jet diffusion 10 68 flames studiedin this laboratory, _3'7andwill be discussedmore fully when flame structure is discussed.The HRTEM imagesin Fig. 1 (Flame4) illustratedin Fig. 3 (atz=82 mm),however,the flame sheetlies beyondthe regionillustrated for the acetylene-nitrogen/airflame (Flame 2) illustrated in Fig. 2 (at z=106 ram) and for the acetylene-benzene-nitrogen/air flame (Flame9) illustrated in Fig. 4 (at z=110 ram) Concentrationsof 02 either progressively increasewith increasing distancefrom the burner exit (Figs. 2 and 3) or progressively increase as the flame sheet is approached after reaching a broad minimum near the burner exit (Fig. 4) Soot Surface Growth RatesPast and present measurements were used to find soot surface growth rates for laminar premixed and diffusion flames. Major assumptions were identical to earlier work, 1"7 as follows:soot mass production is dominated by soot surface growth rather than primary soot particle nucleation, effects of diffusion (Brownian motion) and thermophoresis on soot motion are small so that soot particles convect along the axes of the flames at the local gas velocity, the density of soot is constant (taken to be 1850 kg/m 3 from Ref. 1), and the surface area available for soot growth is equivalent to constant diameter spherical primary soot particles that meet at a point.The justif...

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Experimental investigation on forced convection heat transfer is applied to vehicles' radiator filled with AL 2 O 3 water nanofluid with different concentrations: 0.1%, 0.5%, 1%, 1.5%, and 2% by volume. The experiments are done for three cases, each case corresponds to different heat load, coolant flow rate, and air flow rate to simulate the vehicle engine cooling system at various loads relevant to the cooling system of Toyota Yaris 2007. The coolant and air heat transfer coefficients, Nusselt numbers, heat rate lost by the coolant and absorbed by the air, heat exchanger effectiveness, overall heat transfer coefficients, Reynolds number, and the pumping power are calculated. Log mean temperature difference (LMTD) and effectiveness-number of transfer units ( -NTU) are used to determine the outside air heat transfer coefficient. Results show gradual enhancement in the heat transfer with concentrations 0.1%, 0.5%, and 1% by volume (optimum at 1%); however deterioration occurs at concentrations 1.5% and 2%.