• ### On the Calculation of Diffusion Coefficients in Confined

Mar 11 2004We compute the elements of the diffusion tensor of water as a function of distance from the liquid vapor interface of water Far from the interface the diffusion tensor is found to be isotropic as expected and the diffusion coefficient has the value D ≈ 0 22 2

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• ### Water Vapor Permeation in Plastics

for water vapor it is given in units of mass of water vapor Sometimes the amount of permeant is given in moles Sometimes the term "diffusion coefficient" is used incorrectly instead of permeability which are different properties leading to additional confusion Another complication involves the water vapor transmission rate (WVTR)

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• ### Determination of Mass Transfer Coefficient for Evaporation

Mass transfer coefficient = 4 410-3m/s Partial pressure of water vapour at water surface at 27⁰C P SAT at 27⁰C = 3531 N/m2 Saturation pressure of water vapour in air at 27⁰C and 40% RH P∞ = 0 46221 = 2488 4 N/m2 Total pressure of air = P w + P a = 101 325103 N/m2 C = 𝑃 ρ = MC = 𝑃 𝑅𝑇

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• ### CONDENSATION OF A PURE VAPOR

For a water-cooled condenser tube the coolant-side heat transfer coefficient might typically be around 5 000 W/m 2 K This is of similar magnitude to that found with film condensation of steam (5 000–15 000 W/m 2 K) For organic vapors condensing-side heat transfer coefficients are

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• ### Mass transfer coefficient correlations for volatilization

May 01 2002A numerical scheme to calculate temperature and salinity dependent air-water transfer velocities for any gas Ocean Science 2010 6 (4) 913-932 DOI: 10 5194/os-6-913-2010 M T Johnson A numerical scheme to calculate temperature and salinity dependent air-water transfer

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• ### Water vapor transfer coefficients for calculating the

Data are given on the computation of surface moisture transfer coefficients and vapor permeability coefficients for the diffusion of water vapor through walls The theoretical results are compared with the available experimental values

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• ### Heat Transfer during Spray Cooling of Flat Surfaces with

heat transfer coefficient (HTC) or the Nusselt number which is a measure of the cooling rate due to f orced co n-vection Characterization of the heat transfer coefficient is importa nt for determining the required cooling capa c-ity and corresponding internal properties of the product For this reason a vast amount of work has been devoted

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• ### Heat Transfer of Pipe Flows

Heat transfer of pipe flows On the last tab of the heat transfer resistance tool dialog in HTflux you will find a very versatile tool to calculate the heat transfers coefficients (resistances) of pipe flows for gases and liquids To get these actual transfer coefficients quite some fluid dynamical calculations are

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• ### Calculating the Oxygen Diffusion Coefficient in Water

Calculating the Oxygen Diffusion Coefficient in Water Tom Richard This discussion is part of a section on oxygen transport and oxygen diffusion in compost which provides background on the general concepts and equations Estimates of the diffusion coefficient in liquids often use a correlation developed by Wilke and Chang 1955 which is based on the Stokes-Einstein equation:

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• ### Heat Transfer Coefficient Calculator

Being able to efficiently add or remove heat is the primary function of a thermal fluid The heat transfer coefficient is the calculated amount of heat that passes between the thermal fluid to or from any given surface it comes in contact with by way of convection – with the driving force behind the transfer of heat being the temperature differential between the two

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• ### Water Vapor Migration and Condensation Control in

Equations 6 and 7 are the vapor diffusion equations used to calculate the amount of water vapor that passes through the wall or ceiling cavity The overall coefficient of vapor transmission M is determined by adding the resistances to vapor transmittence for the construction materials (and air films) and then taking the inverse of that summation

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• ### Calculating the Oxygen Diffusion Coefficient in Water

Calculating the Oxygen Diffusion Coefficient in Water Tom Richard This discussion is part of a section on oxygen transport and oxygen diffusion in compost which provides background on the general concepts and equations Estimates of the diffusion coefficient in liquids often use a correlation developed by Wilke and Chang 1955 which is based on the Stokes-Einstein equation:

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• ### What is Heat Exchanger

Consider a parallel-flow heat exchanger which is used to cool oil from 70C to 40C using water available at 30C The outlet temperature of the water is 36C The rate of flow of oil is 1 kg/s The specific heat of the oil is 2 2 kJ/kg K The overall heat transfer coefficient U = 200 W/m 2 K Calculate the logarithmic mean temperature difference

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• ### Solved: Saturated Water Vapor Has A Flow Rate Of 1 5 Kg/s

On the tube side city water is used as the cold fluid The city water enters the thin-walled tubes at 17C and leaves at 57C Assume an overall heat transfer coefficient of 2000 W/m2-K a Sketch b Assumptions c Obtain the steam properties: hfg and saturation temperature Obtain the city water properties: only Cp is needed d

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• ### NASA Technical Reports Server (NTRS)

Sep 02 2013Local heat-transfer coefficients for condensation of steam in vertical downflow within a 5/8-inch-diameter tube Heat transfer coefficients of steam condensation in vertical downflow with liquid-vapor interface inside small tube-type condenser Document ID 19660008881

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• ### Heat Transfer Calculator

Heat transfer takes place through conduction convection and radiation This easy-to-use series of calculators will quickly let you calculate basic heat transfer rates as well as rates for both conduction and convection Calculate free convection by entering surface area heat transfer coefficient and surface and fluid temperatures

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• ### Transfer coefficients of momentum heat and water vapour

transfer coefficients because any bias in them will propagate directly to the flux variables – Land-atmosphere interactions are driven by the fluxes of momentum sensible heat and water vapor between the earth's surface and the atmosphere – Even though frequently used in quantifying these fluxes in

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• ### Heat Transfer Calculator

Heat transfer takes place through conduction convection and radiation This easy-to-use series of calculators will quickly let you calculate basic heat transfer rates as well as rates for both conduction and convection Calculate free convection by entering surface area heat transfer coefficient and surface and fluid temperatures

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• ### Heat Transfer Coefficient of Liquid

Sep 20 2017In this calculation the percent of variation in between Uo ass Uo cal is less-than 30% So Uo cal value is correct Conclusion: In sugar industry the condensate heater (Duplex heater) heat transfer coefficient will be take around 1000100 Kcal/hr/m 2 / o C Some Related Articles

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• ### Water Is Boiled At 50 C For A Low Pressure Proces

Water is boiled at 50 C for a low pressure process Calculate the boiling heat transfer coefficient and the heat flux for boiling using a horizontal surface of 3 2 mm of flat glass with a thermal conductivity of 1 02 W/(m K) The other side of the glass consists of air at 56 C having a heat transfer coefficient

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• ### 1 0 GAS TRANSFER

1 Calculate it from published vapor pressure and solution data 2 Measure it in a system at equilibrium 3 Strip the dissolved gas into an absorber and measure the amount stripped kG = gas film mass transfer coefficient = DO 2 G H = Henry's coefficient for O2 in water [length]2 [time]2 C

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• ### Water Vapor Permeation in Plastics

for water vapor it is given in units of mass of water vapor Sometimes the amount of permeant is given in moles Sometimes the term "diffusion coefficient" is used incorrectly instead of permeability which are different properties leading to additional confusion Another complication involves the water vapor transmission rate (WVTR)

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• ### Super Heated Steam Water Heat Transfer Coefficients

Dec 26 2007Super Heated Steam Water Heat Transfer Coefficients - posted in Industrial Professionals: HiUsually we use saturated steam for heating purposes also the correlations for finding the condensing steam coefficients are commonly available What about Super heated steam- Water heat transfer Coefficients are there any different formulas to be used for this purpose or we should use

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• ### Calculating the Heat Transfer Coefficient for Flat and

Apr 10 2019Calculating the heat transfer coefficient in irregular/complex geometries (like a corrugated plate) Note that the flow regime is an important consideration because the heat transfer coefficient is dependent on the velocity In both cases a pragmatic condition such as a fast flow in a blower system or an electronic chip cooling device needs

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• ### Heat exchangers calculation and selection

The sodium hydroxide flow is 19000 kg/h Water vapor condensate with a flow rate of 16000 kg/h and initial temperature of 95C is used as a heating agent Assume that heat transfer coefficient is 1400 W/m 2 deg Please calculate basic parameters of the plate heat exchanger Solution: Let's find the amount of heat transferred

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• ### Answered: Bottom Top Water temperature F Water

Apr 28 2020Water vapor pressure at the top of the column P s Atop =1 995 psia Water mole fraction in the air at the bottom of the column y A b bottom = 0 001609 Water mole fraction in the air at the top of the column y A b top = 0 0882 'a' is the mass transfer area A per unit volume V of the tower

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• ### Chapter 3 Convective Mass Transfer

Air at 32 oC is humidified by flowing over a 1 2-m-long container filled with water The interfacial temperature is 20 oC If the initial humidity of the air is 25% and its velocity is 0 15 m/s calculate (a) the convective mass transfer coefficient and (b) the amount of water

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• ### Water Vapor Permeation in Plastics

for water vapor it is given in units of mass of water vapor Sometimes the amount of permeant is given in moles Sometimes the term "diffusion coefficient" is used incorrectly instead of permeability which are different properties leading to additional confusion Another complication involves the water vapor transmission rate (WVTR)

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