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Shengqiang Shen - One of the best experts on this subject based on the ideXlab platform.

  • 3d numerical study of the liquid Film distribution on the surface of a horizontal tube falling Film Evaporator
    International Journal of Heat and Mass Transfer, 2018
    Co-Authors: Xiaocui Zhang, Shenglin Quan, Shengqiang Shen
    Abstract:

    Abstract In this paper, the volume-of-fluid (VOF) model is adopted to simulate the distribution and flow of a liquid Film on the outer surface of the horizontal tube of a falling-Film Evaporator. The plain tube diameter and the spray distance are 25.4 and 22 mm respectively. The temporal variation characteristics of inline jet flow, the adjacent liquid column, and the steady-state Film thickness distribution over the horizontal tubes are analyzed. To better compare with the experimental results, two kinds of numerical simulation medium, water and ethylene glycol, are chosen. The results of the 3-D numerical simulations and experiment are in good agreement. The results show that the jet flow can be divided into inline jet flow and staggered jet flow. Furthermore, a trough forms between the adjacent liquid columns under inline jet flow, whereas a crest forms between the adjacent liquid columns under staggered jet flow. In addition, the liquid viscosity is a crucial factor affecting the spreading of the liquid Film. The appearance of the crest between adjacent liquid columns results in staggered jet flow.

  • Analysis of heat transfer critical point in LT-MEE desalination plant
    Desalination, 2018
    Co-Authors: Shengqiang Shen, Luyuan Gong
    Abstract:

    Abstract Based on the internal relationship of thermodynamic and structure parameters of the low-temperature multi-effect evaporation (LT-MEE) desalination plant, calculation of the temperature difference distribution in a typical horizontal-tube falling Film Evaporator was carried out. Results show that the reduction of effective temperature difference caused by various thermodynamic losses occupies a large proportion of the apparent temperature difference in horizontal-tube falling Film Evaporator. The distribution of effective heat transfer temperature difference is extremely un-uniform in tube bundle. Under some conditions, the local effective temperature difference in the Evaporator could be zero, and reverse heat transfer might even appear. Through the analysis of the thermodynamic losses in a desalination plant, the heat transfer critical point and the effective heat transfer critical point are proposed for better guiding the thermal design of multi-effect evaporation desalination plant.

  • parametric distributions of a horizontal tube falling Film Evaporator for desalination
    Desalination and Water Treatment, 2016
    Co-Authors: Luyuan Gong, Shengqiang Shen, Xingsen Mu
    Abstract:

    AbstractThree independent experiments which correspond to the characteristic study on the performance of the horizontal-tube falling Film Evaporators were carried out, and each came out with a validated model for its performance prediction. A comprehensive distributed parameter model was developed based on the above three models to simulate a large tube bundle consisting of 160 rows and 80 columns aluminum-brass tubes in a horizontal-tube falling Film Evaporator. The simulation was conducted with the superficial evaporation temperature on the shell side of 60°C, the superficial overall temperature difference of 3.0°C, the inlet brine salinity of 30 g/kg, the inlet brine spray density of 0.06 kg/m s, and the maximum steam inlet velocity of 40 m/s. The non-uniform distributions of several thermal parameters are presented and discussed.

  • numerical study of falling Film thickness over fully wetted horizontal round tube
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Lin Mu, Shengqiang Shen
    Abstract:

    Abstract The numerical investigation was performed to analyze the Film thickness characteristics over fully wetted horizontal round tube in a falling Film Evaporator using commercial CFD code Fluent 6.3.26. A two-dimension multi-phase flow model for numerical simulation was developed under adiabatic condition. The temporal variation characteristics of Film flow process and the steady Film thickness distribution over horizontal tubes were analyzed in detail. It was found that the whole process of liquid Film flowing along the horizontal tube surface includes the transient sub-process and steady state sub-process, and the former can be divided into five stages to be analyzed. The obviously asymmetric distribution of Film thickness is captured by the simulation results. The Film thickness increases with the increase in Film Reynolds number. An obvious zone without liquid is formed very closely to the lower stagnation point, and the size of the zone is bigger when the Reynolds number is higher.

  • three dimensional heat transfer coefficient distributions in a large horizontal tube falling Film Evaporator
    Desalination, 2015
    Co-Authors: Luyuan Gong, Shengqiang Shen, Xingsen Mu, Xue Chen
    Abstract:

    Abstract The distributions of the heat transfer coefficient in a large horizontal-tube falling Film Evaporator under different operating conditions were investigated with numerical simulation in this paper based on the distributed parameter model (DPM). The heat transfer coefficient distributions along the tube row direction, tube length direction, and tube column direction were analyzed with the brine inlet spray density ranging from 0.05 kg/m s to 0.09 kg/m s and the brine inlet salinity from 30 g/kg to 50 g/kg. Results show that the heat transfer coefficient has higher values for the evaporating zone than the preheating zone. With the operating conditions included in this paper, the change of brine inlet salinity leads to a wider variation range of heat transfer coefficient along the tube length direction for the evaporating zone than the change of brine inlet spray density. The change of brine inlet spray density leads to a wider variation range of heat transfer coefficient along the tube row direction for the first tube pass and along the tube length direction for the preheating zone than the change of brine inlet salinity.

He Xiao-hua - One of the best experts on this subject based on the ideXlab platform.

  • 3D parametric design of thin Film Evaporator based on solidWorks
    Machinery Design and Manufacture, 2020
    Co-Authors: He Xiao-hua
    Abstract:

    By the development of 3D CAD technology,2D drawing can not be satisfied with the requirement of most customers.On the basic of self-developed 2D parametric design system of thin Film Evaporator,the 3D parametric design and virtual assembling design of thin Film Evaporator were realized by the development of SolidWorks based on Visual Basic.Through the application of 3D parametric technology,the design level of thin Film Evaporator can be improved and the exploiting period can be shortened,and the foundation can be established for subsequent structure optimization analysis.

  • Finite element analysis on rotor dynamics performance of thin-Film Evaporator
    Machinery Design and Manufacture, 2020
    Co-Authors: He Xiao-hua
    Abstract:

    The rotor is the key part of the Thin-Film Evaporator.Unbalance force of system will amplify the vibration amplitude of the rotor and aggravate the abrasion of the scraper,which results in the failure of the scraper.The 3D model of the rotor was made by using the software Solidworks and seamless link from Solidworks to ANSYS was realized.Modal analysis of the rotor of the Thin-Film Evaporator was made by using the software ANSYS Workbench and modal parameters of the rotor were deduced.Dynamic analysis of the rotor system of Thin-Film Evaporator was achieved by making unbalance response analysis of the unbalance mass in different scrapers.It provides the real-time monitoring for the security of service for the Thin-Film Evaporator and it is of great value.

  • Process calculation and aided design system of the wiped thin Film Evaporator based on CFD
    Food and Machinery, 2020
    Co-Authors: He Xiao-hua
    Abstract:

    The aided design system for thin Film Evaporator was developed by Visual Basic 6.0 exploiting technology. Four parts,that is design calculation, parametric drawing, results output and management system are included in the system. A calculation method of liquid Film thickness for high viscosity fluid was put forward by CFD analysis of fluids in thin Film Evaporator. Based on the results, the process calculation of thin Film Evaporator was realized by synthetically considering the optimum feed rate derived from CFD simulation. The status of manual calculation or engineering magnification estimation for process calculation was ended by the development of the aided design system for thin Film Evaporator. Also, the design cycle can be effectively shortened, the popularization and application of the equipment can be quickened and therefore the research level of the equipment can be improved.

M J Urbicain - One of the best experts on this subject based on the ideXlab platform.

  • determination and correlation of heat transfer coefficients in a falling Film Evaporator
    Journal of Food Engineering, 2006
    Co-Authors: J S Prost, M T Gonzalez, M J Urbicain
    Abstract:

    Abstract The aim of the work was to determine the heat transfer parameters of a single effect Evaporator under different operating conditions, in order to extrapolate them to a multiple effect unit. The falling Film Evaporator consisted of 12 stainless steel vertical tubes, 1″ OD and 3 m long, having an evaporation capacity of 240 kg/h. In this unit the conditions of each effect of a multiple effect Evaporator were simulated, varying the feed concentration and the pressure, setting in this way the saturation temperature and the transfer regime. Obtained values were correlated by means of an equation that links the heat transfer coefficient with the fluid properties, geometric parameters and flow conditions. Comparison with existing correlations was carried out.

Jean Vasseur - One of the best experts on this subject based on the ideXlab platform.

  • experimental results and modeling of boiling heat transfer coefficients in falling Film Evaporator usable for Evaporator design
    Chemical Engineering and Processing, 2009
    Co-Authors: Tarif Ali Adib, Bertrand Heyd, Jean Vasseur
    Abstract:

    Abstract The aim of this paper is to describe the variation laws of the boiling heat transfer coefficient (h) versus the main process parameters, using a pilot scale falling Film Evaporator as found in many food industries. Sugar solutions at different concentrations are used as a model of Newtonian liquid food. The studied parameters affecting boiling heat transfer coefficient (h) in the falling Film Evaporator are: the dry matter concentration XDM (or Brix for sugar solution), the evaporating temperature (θL) or pressure (P) taking into account the boiling point elevation (BPE), the heat flux ϕ or the temperature difference between the heated surface and boiling liquid temperature (Δθ) and the specific mass flow rate per unit of perimeter length (Γ). The nature of heated surface is kept constant (stainless steel) and the effect of the emitted vapor velocity is not taken into account in our study. The variations of h with ϕ or Δθ, are given for pure water and sugar solutions at different concentrations (10%, 30%, 50% and 70%), and interpreted in relation with the two boiling regimes (non-nucleate and nucleate). The transition between non-nucleate regime and nucleate regime has also been visually observed. The critical specific mass flow (Γcri) for water and sugar solution at dry matter concentration 50% has been studied. The variations of h in function of X and θL at Γ = 0.56 (kg m−1 s−1) at three different heat fluxes (2, 20 and 80 kW m−2) have been presented. Two models to correlate h in function of viscosity at Γ = 0.56 (kg m−1 s−1) at two different heat fluxes (20 and 80 kW m−2) have been established, and have been compared with a bibliographic model presented by Van der Poel et al. [P.W. Van der Poel, H. Schiwec, T. Schwartz, Sugar Technology Beet and Cane Sugar Manufacture, Verlag Dr. Albert Bartens KG, Berlin, 1998]. In this paper, experimental results and experimental models, for prediction h in sugar solutions in function of XDM, θL (°C), ϕ (kW m−2) and Γ (kg m−1 s−1) are presented.

Xingsen Mu - One of the best experts on this subject based on the ideXlab platform.

  • parametric distributions of a horizontal tube falling Film Evaporator for desalination
    Desalination and Water Treatment, 2016
    Co-Authors: Luyuan Gong, Shengqiang Shen, Xingsen Mu
    Abstract:

    AbstractThree independent experiments which correspond to the characteristic study on the performance of the horizontal-tube falling Film Evaporators were carried out, and each came out with a validated model for its performance prediction. A comprehensive distributed parameter model was developed based on the above three models to simulate a large tube bundle consisting of 160 rows and 80 columns aluminum-brass tubes in a horizontal-tube falling Film Evaporator. The simulation was conducted with the superficial evaporation temperature on the shell side of 60°C, the superficial overall temperature difference of 3.0°C, the inlet brine salinity of 30 g/kg, the inlet brine spray density of 0.06 kg/m s, and the maximum steam inlet velocity of 40 m/s. The non-uniform distributions of several thermal parameters are presented and discussed.

  • three dimensional heat transfer coefficient distributions in a large horizontal tube falling Film Evaporator
    Desalination, 2015
    Co-Authors: Luyuan Gong, Shengqiang Shen, Xingsen Mu, Xue Chen
    Abstract:

    Abstract The distributions of the heat transfer coefficient in a large horizontal-tube falling Film Evaporator under different operating conditions were investigated with numerical simulation in this paper based on the distributed parameter model (DPM). The heat transfer coefficient distributions along the tube row direction, tube length direction, and tube column direction were analyzed with the brine inlet spray density ranging from 0.05 kg/m s to 0.09 kg/m s and the brine inlet salinity from 30 g/kg to 50 g/kg. Results show that the heat transfer coefficient has higher values for the evaporating zone than the preheating zone. With the operating conditions included in this paper, the change of brine inlet salinity leads to a wider variation range of heat transfer coefficient along the tube length direction for the evaporating zone than the change of brine inlet spray density. The change of brine inlet spray density leads to a wider variation range of heat transfer coefficient along the tube row direction for the first tube pass and along the tube length direction for the preheating zone than the change of brine inlet salinity.

  • Numerical investigation on characteristics of falling Film in horizontal-tube falling Film Evaporator
    Desalination and Water Treatment, 2014
    Co-Authors: Wei-guo Jiang, Shengqiang Shen, Xingsen Mu
    Abstract:

    AbstractHorizontal-tube falling Film technology is widely used in multi-effect desalination plant. The Film characteristics of falling water Film outside the tubes in horizontal-tube falling Film Evaporator were simulated. The numerical result was compared with the experimental result and they were proven with good agreement. The Film thickness distribution at different Reynolds number and different circular angle had been investigated. Also, the effects of liquid flow rate and tube diameter on the Film thickness distribution were discussed in detail. Numerical simulation result shows that, with the increase in Reynolds number, the falling Film thickness at a certain circumferential angle increases with almost linear growth rate, and the thinnest Film at the surface of the tube appears at the angle of about 120°. The result also indicates that the local dry out spot on the surface of the tube would occur when the fluid flow rate decreases to a certain value. In addition, the Film thickness decreases with ...