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Mustafa Seker - One of the best experts on this subject based on the ideXlab platform.

  • Residence Time distributions of starch with high moisture content in a single screw extruder
    Journal of Food Engineering, 2005
    Co-Authors: Mustafa Seker
    Abstract:

    Starch was extruded with sodium trimetaphosphate and sodium hydroxide in a single-screw extruder with a mixing element at 28.5%, 35.5%, and 41.2% moisture content (wet basis) and 90, 140 and 190 rpm screw speeds. The effects of moisture content of starch on Mean Residence Time, spread of Residence Time distribution curve, and flow pattern were determined at three screw speeds. Increasing the screw speed reduced Mean Residence Time at the moisture contents between 28.5% and 41.2%. Increasing the moisture content from 28.5% to 41.2% did not significantly affect the Mean Residence Time. The spread of Residence Time distribution curve was reduced as screw speed was increased, but was not affected as moisture content was increased from 28.5% to 41.2%. The flow pattern was between plug flow and mixed flow. Two flow models were used to represent the flow pattern in the extruder. The parameters of each model were determined by a nonlinear regression, and the fitness of experimental data to the flow models was examined.

  • Distribution of the Residence Time in a single-screw extruder with differing numbers of mixing elements
    International Journal of Food Science and Technology, 2004
    Co-Authors: Mustafa Seker
    Abstract:

    Summary Starch was extruded with sodium trimetaphosphate and sodium hydroxide in a single-screw extruder at 40% moisture content and screw speeds of 90 and 140 r.p.m. The effect of screw configurations, which included one and two mixing elements, on Mean Residence Time, spread of Residence Time distribution (RTD), and flow pattern were determined. Increasing the screw speed and reducing the number of mixing elements reduced Mean Residence Time. Higher RTD spread values were obtained at a screw speed of 90 r.p.m. when compared with 140 r.p.m. and increasing the number of mixing elements in the screw increased the RTD spread. The flow pattern was between plug and mixed flow, and increasing the number of a mixing element in the screw did not significantly affect the flow pattern in the single-screw extruder.

Yu Zhongbo - One of the best experts on this subject based on the ideXlab platform.

  • evaluating infiltration mechanisms using breakthrough curve and Mean Residence Time
    Water Resources Management, 2013
    Co-Authors: Qu Simin, Bao Weimin, Zhou Minmin, Yu Zhongbo, Shi Peng, Jiang Peng
    Abstract:

    Determination of infiltration mechanism is crucial for the calculation of infiltration flux in the soil which would influence the water balance computation. Two infiltration experiments with different isotopic compositions of rainfall were conducted to analyze the infiltration type by measuring isotopic concentrations (deuterium and oxygen 18) of collected outflow water samples. Models with three transfer functions were used to simulate the isotopic variation of outflows in a soil column. The model performance was evaluated with the comparison of computed and observed isotopic values of outflow. Breakthrough curve based on the isotopic composition of rainfall, initial soil water and outflow, and Mean Residence Time estimated on the best fitting transfer function model were applied to identify the infiltration type in the soil. The results show that infiltration type determination using the comparison between estimated and observed Mean Residence Time and breakthrough curve are similar. Furthermore, we found that soil structure and isotope measurement error affected the determination of Mean Residence Time. Results from this study may provide a framework for describing the infiltration processes in the soil column.

Kit L Yam - One of the best experts on this subject based on the ideXlab platform.

  • relationships between Residence Time and process variables in a corotating twin screw extruder
    Journal of Food Engineering, 1994
    Co-Authors: Binoy K Gogoi, Kit L Yam
    Abstract:

    Abstract Degerminated yellow corn meal was extruded with a Werner and Pfleiderer ZSK-30 corotating twin-screw extruder under a wide range of processing conditions. The effects of process variables on Mean Residence Time were examined by changing one variable at a Time, as well as by applying statistical models to analyze situations when two or more process variables were changing. The most significant process variables affecting Mean Residence Time were screw speed followed by throughput. Moisture content had only borderline effect, while die pressure and die temperature had no significant effect.

Titus U Nwabueze - One of the best experts on this subject based on the ideXlab platform.

  • Residence Time distribution rtd in a single screw extrusion of african breadfruit mixtures
    Food and Bioprocess Technology, 2010
    Co-Authors: Titus U Nwabueze
    Abstract:

    Mixtures of African breadfruit (Treculia africana Decne), corn, and defatted soybean were extruded in a single-screw Brabender laboratory extruder at process variables derived from a second-order central composite design. The variables consisted of feed composition (0–100% breadfruit, 0–55% soybean, and 0 or 5% corn); fed moisture (15–27%), and screw speed (100–180 rpm). Effects of these variables on Residence Time distribution were investigated using Congo red as tracer. The extrudate spent longer Time in the extruder as feed moisture or screw speed was decreased from 27% to 15% or 180 to 100 rpm, respectively, thereby increasing the Residence Time distribution characteristics. At 70% feed composition and screw speed of 140 rpm, Mean Residence Time (\(\overline t \)) increased from 40 to 50 s, whereas extrudate total collection Time (tc) increased from 65 to 70 s. At screw speed of 100–180 rpm, Mean Residence Time (\(\overline t \)) decreased from 55 to 35 s, whereas extrudate total collection Time (tc) decreased from 75 to 65 s. At 100% African breadfruit composition, these Time values decreased to 35 and 70 s, respectively, at the same screw speed, indicating the significant influence of feed composition and soybean addition to the mixture on Residence Time distribution. Residence Time distribution curves indicated an early breakthrough Time of 20 s at maximum screw speed (180 rpm), minimum tail of 65 s, and a plug flow pattern of the extrudates.

Xiaoyan Liu - One of the best experts on this subject based on the ideXlab platform.

  • Mean Residence Time and hold up of solids in rotary kilns
    Chemical Engineering Science, 2006
    Co-Authors: Xiaoyan Liu, Eckehard Specht
    Abstract:

    The influence of operational variables on the Mean Residence Time (MRT) and hold-up of the solids in rotary kilns has been investigated by many researchers. However, their reports on the influence of the feed rate on MRT, for example, are not consistent with one another. In this study, experiments are conducted on a 400 mm ID pilot kiln with a cylindrical discharge dam. Sand is used as the testing solids. MRT and the hold-up are measured under various feed rates and rotation speeds. Experimental results indicate that MRT increases slightly with the feed rate, and that the gradient is smaller at high rotation speeds. The hold-up shows a near-linear increase with the mass of feed per kiln rotation. The experimental data are then used to test equations provided by different researchers for the prediction of MRT. Comparisons show that, results of the empirical equation from Sullivan, J.D., Maier, C.G., Ralson, O.C. [1927. Passage of solid particles through rotary cylindrical kilns. U.S. Bureau of Mines Technical Paper No. 384.] agree well with measurements for the cases of low kiln loadings, while the numerical model of Saeman, W.C. [1951. Passage of solids through rotary kilns: factors affecting Time of passage. Chemical Engineering Progress 47, 508-514.] gives good predictions over the entire range of parameters considered.