Zufei Huan

Bio: Zufei Huan is an academic researcher from University of Science and Technology of China. The author has contributed to research in topics: Methyl methacrylate & Poly(methyl methacrylate). The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Width effects on downward flame spread over poly(methyl methacrylate) sheets

Abstract: The experiments of downward flame spread over poly(methyl methacrylate) sheets with different dimensions were conducted in this study. In comparison with flame spread over samples under infinite wi...

Influence of vertical channel on downward flame spread over extruded polystyrene foam

Abstract: The influence of vertical channel with various structure factors (α) on downward flame spread over extruded polystyrene (XPS) foam is investigated. The flame shape, flame height (Hf), temperature in the channel (Tv) and on the curtain wall surface (Tc), flame spread rate (Vf), and induced air flow (Q) are obtained. Hf first drops and then increases as α rises, attributing to similar changing trends of induced airflow rate and Froude number. Concerning the temperature history, Tc > Tv at the initial stage while Tc T c ‾ (average value) and T v ‾ drop as α rises, and T v ‾ > T c ‾ under most conditions. A model is established to predict the total, convective and radiative heat fluxes transferred to preheating zone. The convective heat flux is more dominant than the radiative heat feedback from the curtain wall. Vf first rises and then drops as α increases. For α

Experimental and theoretical study on downward flame spread over uninhibited PMMA slabs under different pressure environments

Abstract: This paper presents an experimental and theoretical study of side-edge effects on downward flame spread over two parallel polymethyl methacrylate (PMMA) slabs under different pressure environments. Identical experiments of downward flame spread over thin PMMA slabs with side-edges unrestrained were conducted at different altitudes in Hefei (102 kPa), Geermu (73.2 kPa) and Lhasa (66.3 kPa). Experimental results show that the flame spread rate is controlled by ignition along the side-edge, rather than at the center of the samples, for experiments with both single and two parallel slabs. Based on these results, a thermal model is developed which describes flame spread along the edge and quantitatively agrees with experimental results. In the parallel-slab case, convective heating appears to influence the spread rate only when the separation distance is very small, with radiative heating playing a more important role as separation distance increases. The angle of the pyrolysis front, formed between the faster side-edge spread and slower center-region spread, hardly changes with pressure, but changes significantly with separation distance, due to differing modes of heat transfer between the side-edge and center region. In addition, variations of flame height with pressure and separation distance are reasonably interpreted from diffusion flame theory.

Macroscopic characteristics and prediction model of horizontal extension length for syngas jet flame under inclined conditions

Abstract: As an important industrial raw material, syngas can be used for hydrogen production, and its main components include hydrogen and carbon monoxide. Experiments were conducted on syngas (ratio of CO and H2 is 1:1) to study the effects of the nozzle inclined angle and diameter as well as the heat release rate on the characteristics of syngas jet flame. Three nozzles with different diameters, 5 mm, 10 mm, and 15 mm, were used in this study. Four different inclined angles of the nozzle corresponding to 0°, 30°, 60°, and 90° were employed. It was found that the normalized horizontal extension length of jet flame (L/D) varies with nozzle diameter and fuel flow rate, and increases exponentially as the dimensionless heat release rate ( Q ∗ ) increases for the nozzle with inclined angles of 0°–60°. By modifying the dimensionless heat release rate and fitting the experimental data, a unified empirical model, which is the first of its kind to date, is established. The model can be used to estimate the horizontal extension length of the syngas jet flame for nozzles with different diameters and inclined angles. For jet flame at an inclined angle of 90°, the normalized jet flame width was exponentially proportional to the modified Froud number with a power of 0.39.

Numerical study of horizontal flame spread over PMMA surface in still air

Abstract: Flame spread over the horizontal surface of polymethyl methacrylate (PMMA) has been studied numerically by a coupled model of heat and mass transfer describing the feedback between gas-phase flame and solid fuel Mathematical formulation has been defined by non-stationary two-dimensional elliptic equations applied both for gas phase and solid fuel The computational procedure is based on modification of the OpenFOAM open-source code Results of predictions have been compared with the data of comprehensive experimental investigation of the thermal and chemical structure of PMMA flame Good agreement has been obtained for the detailed gas-phase and the solid fuel temperature and species concentrations profiles, as well as for the macroscopic parameters: the flame spread rate, the total mass regression rate and the length of the pyrolysis zone Based on the analysis of thermal degradation of methylmethacrylate in inert surrounding, the concept of reduced molar weight for gaseous products of PMMA pyrolysis has been proposed, which provided better agreement for fuel distribution in the gas phase

Prediction of Three-Dimensional Downward Flame Spread Characteristics over Poly(methyl methacrylate) Slabs in Different Pressure Environments

Abstract: The present study is aimed at predicting downward flame spread characteristics over poly(methyl methacrylate) (PMMA) with different sample dimensions in different pressure environments. Three-dimensional (3-D) downward flame spread experiments on free PMMA slabs were conducted at five locations with different altitudes, which provide different pressures. Pressure effects on the flame spread rate, profile of pyrolysis front and flame height were analyzed at all altitudes. The flame spread rate in the steady-state stage was calculated based on the balance on the fuel surface and fuel properties. Results show that flame spread rate increases exponentially with pressure, and the exponent of pressure further shows an increasing trend with the thickness of the sample. The angle of the pyrolysis front emerged on sample residue in the width direction, which indicates a steady-burning stage, varies clearly with sample thicknesses and ambient pressures. A global non-dimensional equation was proposed to predict the variation tendency of the angle of the pyrolysis front with pressure and was found to fit well with the measured results. In addition, the dependence of average flame height on mass burning rate, sample dimension and pressure was proposed based on laminar diffusion flame theory. The fitted exponent of experimental data is 1.11, which is close to the theoretical value.