heat and mass transfer lecture notes ppt

... relative to q′′ conv and εEb and dT/dt is still significant PROBLEM 12 .92 KNOWN: Temperatures of furnace wall and top and bottom surfaces of a planar sample Dimensions and emissivity ... uniform temperature, (2) Surroundings are isothermal and large compared to the plate, and (3) Coatings are diffuse and gray so that ε = α and ρ = 1 - ε . ANALYSIS: (a) When viewing the ... and () 12s ,T F λλ − is the fraction of the spectral band between λ 1 and λ 2 in the spectrum for a blackbody at T s , ()()() 12s 2s 1s ,T 0 ,T 0 ,T FFF λλ λ λ −−− =− (2) where the band

Ngày tải lên: 08/08/2014, 17:20

... are accepted in Eq. (31): Heat and Mass Transfer – Modeling and Simulation 152 i. the external mass transfer resistance is negligible, but the internal mass transfer resistance is large ... 196 3) Natural Convection Mass- Transfer Measurements on Spheres and Horizontal Cylinders by an Electrochemical Method International Journal of Heat and Mass Transfer, Vol 6, No 10, ... (2000) Exergy and Energy Analysis of Food Drying... surface area of dried solid (m2) a,b constants (Eqs (35), (55), and (63)) 162 Heat and Mass Transfer – Modeling and Simulation

Ngày tải lên: 19/06/2014, 10:20

... 3 O 5 , and Ti 4 O 7 . Heat and Mass Transfer – Modeling and Simulation 176 Elements M g K Na Ca Si Al Fe Ti Chemical form MgO K 2 O Na 2 O CaO SiO 2 Al 2 O 3 FeO TiO 2 % in mass 10.2 ... temperatures between 1700 and 2000 K the mole numbers of Ru, RuO, and RuO 2 increase by an amount smaller that the amount of decrease of the Heat and Mass Transfer – Modeling and Simulation 178 ... Switzerland; Cambridge; New York: VCH, (1989) 188 Heat and Mass Transfer – Modeling and Simulation [19] Chase Malcolm, NIST-JANAF, Thermochemical Tables, Fourth Edition, J of Phys and

Ngày tải lên: 19/06/2014, 10:20

... 202 Heat and Mass Transfer – Modeling and Simulation  is the density, and Dm is the diffusion coefficient B0 is the magnetic flux density, L is the * electrode length, and ... between the bulk and surface Equations (31) and (34) are connected... initial amplitude, 0  0  s 2 s2 XY  cr = 2  kmax (41) 204 Heat and Mass Transfer – Modeling and Simulation ... asymmetrical fluctuations control the total electrode reaction, and the total electrolytic current increases. Heat and Mass Transfer – Modeling and Simulation 198 2.2 The second instability in 3D

Ngày tải lên: 19/06/2014, 10:20

... HEAT AND MASS TRANSFER – MODELING AND SIMULATION Edited by Md Monwar Hossain Heat and Mass Transfer – Modeling and Simulation Edited by ... Rodrigo and José J. Linares Chapter 3 Numerical Analysis of Heat and Mass Transfer in a Fin -and- Tube Air Heat Exchanger under Full and Partial Dehumidification Conditions 41 Riad Benelmir and ... 3 is concerned with the description and analysis of heat and mass transfer processes in a fin -and- tube air heater. Hydrogen production by steam reforming and the process intensification strategies

Ngày tải lên: 26/06/2014, 23:20

... and resistance of wire Wire diameter and emissivity Thickness, emissivity and thermal conductivity of coating Temperature of ambient air and surroundings Expression for heat transfer ... the optimal heater dimensions. PROBLEM 3.37 KNOWN: Inner and outer radii of a tube wall which is heated electrically at its outer surface and is exposed to a fluid of prescribed h and T ∞ . Thermal ... ∞ . Thermal contact resistance between heater and tube wall and wall inner surface temperature. FIND: Heater power per unit length required to maintain a heater temperature of 25 ° C. SCHEMATIC:

Ngày tải lên: 08/08/2014, 17:20

... fd_1d_int(Ta,Tb,T1,k,qdot,deltax) /* Node b: interior node; e and w labeled c and a. */ rho*cp*der(Tb,t) = fd_1d_int(Tb,Tc,Ta,k,qdot,deltax) /* Node c: interior node; e and w labeled 2 and b. */ rho*cp*der(Tc,t) = fd_1d_int(Tc,T2,Tb,k,qdot,deltax) ... is exposed to a constant heat flux o q ′′ = 2000 W/m 2 . See also Problem 2.43. FIND : (a) Using spatial and time increments of ∆ x = 5 mm and ∆ t = 20s, compute and plot the temperature ... Using spatial and time increments of ∆x = 4 mm and ∆t = 1s, compute and plot the temperature distributions in the wall for the initial condition, the steady-state condition, and two intermediate

Ngày tải lên: 08/08/2014, 17:20

... Although convection heat transfer substantially exceeds radiation heat transfer, radiation is not negligible and should be included in the analysis If...h_x(x) and Ts(x) 100 80 60 ... correspond to 56 2.4 K and 602.8... 602.8 K, with and without radiation, respectively The time required for the heater to reach 55 2.4 K (with radiation) is t ≈ 155 s (c) If the heater temperature ... the assumption of parallel flow over a flat plate is reasonable. (2) If a finned heat sink is not employed and heat transfer is simply by convection from the 22 ww × base surface, the corresponding

Ngày tải lên: 08/08/2014, 17:20

... prescribed diameter, length and surface temperature FIND: (a) Air outlet temperature and duct heat loss for the prescribed conditions and (b) Calculate and plot q and ∆p for the range ... the overall heat transfer coefficient increases due to increasing h i and the hot fluid maintains a higher temperature as it flows through the tube. Both effects enhance heat transfer to the ... tubing is soldered. Water inlet temperature and flow rate. FIND: (a) Water outlet temperature and heat rate, (b) Variation of outlet temperature and heat rate with flow rate. Variation of water

Ngày tải lên: 08/08/2014, 17:20

... diameter D and length L which satisfies the heat transfer and pressure drop requirements, and (b) Compute and plot the cold stream outlet temperature Tc,o, the heat rate q, and pressure ... (b) Heat rate, hot fluid outlet temperature, overall heat transfer coefficient, and fouling factor after three years. SCHEMATIC: ASSUMPTIONS: (1) Negligible heat loss to the surroundings and ... tube heat exchanger. Overall heat transfer coefficient (U = 500 W/m 2 ⋅ K) and desired heat rate (q = 3000 W). Cold fluid outlet temperature after three years of operation. FIND: (a) Required heat

Ngày tải lên: 08/08/2014, 17:20

... .. and becomes negative (heat transfer from the surface) when Td exceeds 1500 K at h = 540 W / m 2 ⋅ K Both the convection and radiation heat rates, and hence the conduction heat ... rad,o to heat transfer from the outer surface COMMENTS: (1) With no insulation or radiation shield and εi = 0.5, radiative and convective heat 2 fluxes from the ceiling are 18,370 and ... and the prescribed properties of air into the IHT workspace, the < parametric calculations were performed for D2 = 0.06 m and D2 = 0 .10 m For D2 = 1.0 m, Ra ∗ > 100 c and heat transfer

Ngày tải lên: 08/08/2014, 17:20

... (1990). Fundamentals of heat and mass transfer. New York, Wiley. [Hayakawa and Hwang, 1981] Hayakawa, K. and Hwang, P. (1981). Apparent thermophysical constants for thermal and mass exchanges of cookies ... heat undergo heat transfer due to convection and radiation and in the inner part of the dough, the heat. .. b2 where, asp and bsp are the length and width of the sample and L is the ... 1 + b2 where, asp and bsp are the... content and hV and hW are mass transfer coefficients of vapor and water at the surface hV depends on the temperature content and hW depends on

Ngày tải lên: 16/09/2015, 12:42

... Keywords: Biomass Gasification Fixed bed downdraft gasifier Modeling Kinetics Heat and mass transfer Introduction Biomass, including forestry and agricultural residues, industrial, human and animal ... process controlled by both chemical reactions and internal and external mass and heat transfer processes Indeed, interaction between the chemical and transport mechanisms during gasification is ... surface and form drag forces; heat transfer by conduction, radiation and convection between the solid and gas phases and heat losses through the reactor walls; convective and diffusive transport of

Ngày tải lên: 01/08/2016, 09:31

... Hartnett, and Cho, Handbook of Heat Transfer, 3d ed., McGraw-Hill, 1998 Siegel and Howell, Thermal Radiation Heat Transfer, 4th ed., Taylor and Francis, London, 2001 MODES OF HEAT TRANSFER Heat is ... Edwards, Radiation Heat Transfer Notes, Hemisphere Publishing, 1981 Hottel and Sarofim, Radiative Transfer, McGraw-Hill, 1967 Incropera and DeWitt, Fundamentals of Heat and Mass Transfer, 5th ed., ... Patankar, Numerical Heat Transfer and Fluid Flow, Taylor and Francis, London, 1980 Pletcher, Anderson, and Tannehill, Computational Fluid Mechanics and Heat Transfer, 2d ed., Taylor and Francis, London,

Ngày tải lên: 23/08/2017, 23:24

... convection heat transfer is expressed as Q& = hAs (Ts − T∞ ) Disregarding any heat transfer by radiation and thus assuming all the heat loss from the wire to occur by convection, the convection heat transfer ... Steady operating conditions exist Heat 55°C transfer by radiation is disregarded The convection heat transfer coefficient is constant and uniform over the surface Heat transfer from the base of the ... radiation heat transfer between a person and the surrounding surfaces at specified temperatures is to be determined in summer and in winter Assumptions Steady operating conditions exist Heat transfer

Ngày tải lên: 07/03/2018, 16:28

... result of the heat transfer from the ambient air is to be determined Assumptions Steady operating conditions exist Heat transfer by radiation is disregarded The convection heat transfer coefficient ... between W and Btu/h, m and ft, and °C and °F, the convection coefficient in SI units is to be expressed in Btu/h⋅ft2⋅°F Analysis The conversion factors for W and m are straightforward, and are ... warmer environment, and avoiding drafts 1-94C The fan increases the air motion around the body and thus the convection heat transfer coefficient, which increases the rate of heat transfer from the

Ngày tải lên: 07/03/2018, 16:28

... of thermal and mass transfer boundary conditions can be encoun- tered in practice. Standard thermal and mass transfer boundary condition types are often used in theoretical models and experiments, ... (m) l ent,ma Mass transfer entrance length (m) l ent,th Thermal (heat transfer) entrance length (m) l M Turbulence mixing length ( m) l M, ma Turbulence mixing length f or mass transfer (m) l heat Heated ... (m) l th Turbulence mixing length f or heat transfer (m) M Molar mass (kg/kmol) Ma Mach number m Mass fraction; dimensionless constant m Mass (kg); mass of a single molecule (kg) m  Mass flux (kg/m 2 s) N Ratio...

Ngày tải lên: 30/03/2014, 19:20

... Rodrigo and José J. Linares Chapter 3 Numerical Analysis of Heat and Mass Transfer in a Fin -and- Tube Air Heat Exchanger under Full and Partial Dehumidification Conditions 41 Riad Benelmir and ... 3 is concerned with the description and analysis of heat and mass transfer processes in a fin -and- tube air heater. Hydrogen production by steam reforming and the process intensification strategies ... calculations and the experimental data from Silva (2000), respectively. Fig. 11. Adsorption and desorption steps from simulation results (a) and experiments (b) HEAT AND MASS TRANSFER...

Ngày tải lên: 19/06/2014, 10:20

... resistance (R Ω ) Charge transfer CPE Charge transfer resistance (R ct ) Mass transfer resistance (R mt ) CHARGE TRANSFER CONTRIBUTION MASS TRANSFER CONTRIBUTION Mass transfer CPE (a) 0.0 ... Heat and Mass Transfer – Modeling and Simulation 26 circuit constant phase element and resistance, related to the charge transfer processes (kinetic), and another parallel ... access of the reactants, Heat and Mass Transfer – Modeling and Simulation 30 does not only have influence in terms of mass transfer limitations, but in kinetic and ohmic ones due to an excess...

Ngày tải lên: 19/06/2014, 10:20

... natural and forced convective heat and mass transfer regimes for nanofluids flowing in semi-infinite geometries, i.e. external boundary layer flows along Heat and Mass Transfer – Modeling and ... nanofluid. Heat and Mass Transfer – Modeling and Simulation 92 8. Nomenclature C molar concentration, kmol/m 3 P mixed gas pressure, Pa p C Isobaric specific heat capacity, J/(mol·K) ... velocity profiles, streamlines and boundary layer thickness. Heat transfer characteristics are then presented by means of wall temperature distribution and convective heat transfer coefficients. 2....

Ngày tải lên: 19/06/2014, 10:20