advanced heat and mass transfer lecture notes

... both nanofluids, traducing both heat and mass transfer in forced convection It clearly appears that the thermal flow rate is strongly dependent Trang 3Heat and Mass Transfer in External Boundary ... M., (2003) Buoyancy-driven heat transfer enhancement in a two-dimensional enclosure using nanofluids Int J Heat Mass Transf Vol 46 pp.3639-3653 Trang 5Heat and Mass Transfer in External Boundary ... Heat transfer enhancement of nanofluids Int J Heat Fluid Flow, Vol.21 (2000) pp.58-64 Xuan, Y & Roetzel, W 2000 Conceptions for heat transfer correlation of nanofluids Int J Heat Mass Transfer,

Ngày tải lên: 19/06/2014, 10:20

... (2005b) A critical investigation into the heat and mass transfer analysis of counterflow wet-cooling towers International Journal of Heat and Mass Transfer, Vol 48, No 3-4, (January 2005), pp ... California, USA Chengqin, R (2006) An analytical approach to the heat and mass transfer processes in counterflow cooling towers Journal of Heat Transfer, Vol 128, No 11, (November 2006), pp 1142-1148, ... M (2001) Fundamentals of heat and mass transfer in wet cooling towers All well known or are further development necessary Proceedings of 12 th IAHR Cooling Tower and Heat Exchangers, pp 100-107,

Ngày tải lên: 19/06/2014, 10:20

... material, moisture content and temperature Typically the specific heat increases with increasing moisture content and temperature and linear correlation between specific heat and moisture content in ... Poland) The samples of 100 g mass were dried Such a mass ensured final maximum relative error of evaluation of sample moisture content not exceeding 1 % The mass of samples during drying and ... dimensionless Biot number Bi for moisture transfer can be calculated using its definition as: h Rm Bi 2.4 Equation of heat balance of dried biological material heating Heat supplied to the particles of

Ngày tải lên: 19/06/2014, 10:20

... Trang 14 Transfer equation 4.1 Determination of the stoichiometric coefficient To simplify the writing and calculation of the mass transfer equation at the interface, ... oxygen and metals, and the combination of equations (16), (17), (18), (19) and (20), lead to the following equation 1 dX Trang 3The equation (25) is the oxygen matter conservation equation or the transfer ... w i p and x i p represent the interfacial partial pressure and the partial pressure in the carrier gas of species ‘i’ respectively; JT is the total mass flux density with 1 J  J J  and 

Ngày tải lên: 19/06/2014, 10:20

... t (3) where superscripts ‘a’ and ‘s’ imply the asymmetrical and symmetrical fluctuations, respectively C x y z t and m , , ,  C z t m* , are the concentration and the concentration in electrostatic ... the concentration overpotential decreases there, and mass transfer is enhanced As a result, the symmetrical fluctuations always turn unstable, and the 3D nucleus is self-organized (Fig 4a) However, ... same time, rate-determining step is changed from electron-transfer in the electric double layer to mass transfer in the diffusion layer, and expressed by the concentration overpotential; instability

Ngày tải lên: 19/06/2014, 10:20

... Electrical heater is perfectly insulated from dryer wall, (3) Heater and switch are isothermal at Tset, (4) Negligible heat transfer from sides of heater or switch, (5) Switch surface, As, loses heat ... W/m⋅K) and a patch heater could be applied to the back of the block and insulated from below If conduction to both the substrate and insulation could thereby be rendered negligible, heat would be transferred ... small, concurrent heat transfer by radiation and/or conduction must often be considered However, jet impingement is one of the more effective means of transferring heat by convection and convection

Ngày tải lên: 08/08/2014, 17:20

... Electric current 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 ... associated with a composite wall and a thin electric heater.FIND: (a) Equivalent thermal circuit, (b) Expression for heater temperature, (c) Ratio of outer and inner heat flows and conditions for which ... T∞ 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

... 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 times, and ... (c) The heat fluxes for the locations x = 0 and x = L, are plotted as a function of time At the x = 0surface, the heat flux is constant, q„„o = 2000 W/m2 At the x = L surface, the heat flux ... the other isexposed to a constant heat flux oq ′′ = 2000 W/m2 See also Problem 2.43.FIND: (a) Using spatial and time increments of ∆x = 5 mm and ∆t = 20s, compute and plot the temperature distributions

Ngày tải lên: 08/08/2014, 17:20

... times) and using a fittingroutine to determine values for C and m Trang 20 Cylinder diameter and surface temperature Temperature and velocity of fluids in cross flow (a) Rate of heat transfer ... m/s Forvelocities of 1 and 10 m/s, respectively, convection coefficients are 21.1 and 72.8 W/m2⋅K and filmtemperatures are 313.2 and 291.7 K The small values of q and ro and the large value of ... coolant. (a) Average pin convection coefficient, (b) Pin heat transfer rate, (c) Total heat rate, (d) Effect ofvelocity and pin diameter on total heat rate (1) Steady-state conditions, (2) One-dimensional

Ngày tải lên: 08/08/2014, 17:20

... rate and properties of hot fluid Initial temperature, volume andproperties of pharmaceutical Heat transfer coefficient at outer surface and dimensions of coil FIND: (a) Expressions for Tc(t) and ... of prescribed diameter, lengthand 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 of diameters, ... 15KNOWN: Flow rate and inlet temperature of water passing through a tube of prescribed length,diameter and surface temperature FIND: (a) Outlet water temperature and rate of heat transfer to water

Ngày tải lên: 08/08/2014, 17:20

... Tube 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, andpressure drop ... temperatures and overall heat transfer coefficient for a regenerator.Desired regenerator effectiveness Cost of natural gas FIND: (a) Heat transfer area required for regenerator and corresponding heat ... 0.02 m) and fluid inlet and outlet temperatures corresponding to design conditions for a concentric tube heat exchanger Overall heat transfer coefficient (U = 500 W/m2⋅K) and desired heat rate

Ngày tải lên: 08/08/2014, 17:20

... relative to qconv′′ and εEb and dT/dt is still significant Trang 23PROBLEM 12.92KNOWN: Temperatures of furnace wall and top and bottom surfaces of a planar sample.Dimensions and emissivity of sample ... the target, It,emit; and and radiation parameters SCHEMATIC: ASSUMPTIONS: (1) Furnace wall is isothermal and large compared to the billet, (2) Billet surface is diffuse gray, and (3) At, Ad << ... W/m^2.K^4 // Radiation Tool - Band Emission Factor, Total emissivity and absorptivity eps = FL1Ts * eps1 + (1 - FL1Ts) * eps2 /* The blackbody band emission factor, Figure 12.14 and Table 12.1, is */

Ngày tải lên: 08/08/2014, 17:20

... of heat transfer to tube without ash deposit, (b) Rate of heat transfer with an ash deposit of diameter Dd = 0.06 m, (c) Effect of deposit diameter and convection coefficient on heat rate andcontributions ... radiation decreases and becomes negative(heat transfer from the surface) when Td exceeds 1500 K at h=540 W / m2⋅K Both the convectionand radiation heat rates, and hence the conduction heat rate, increase ... entered into the IHT workspace and parametric calculations were performed to explore the effects of h and Dd on the heat rates For Dd = 0.06 m and 10≤ ≤h 1000 W / m2⋅K, the heat rate to the tube, qcond′

Ngày tải lên: 08/08/2014, 17:20

... simultaneous heat and mass transfer problem which transforms a roughdough in to a light, digestive and flavored bread In this process heat is transferredthrough the dough with the help of basic heat transfer ... dimensional heat and masstransfer can be considered to investigate the heat transfer in one direction (here,side with length 2cm) In this model, the surfaces that are exposed to oven heatundergo heat transfer ... Equations Equations for heat transfer and diffusion of liquid water and water vapor are proximated in the discretized computational domain ap-Heat Transfer Equation Equation for heat transfer is discretized

Ngày tải lên: 16/09/2015, 12:42

... process controlled by both chemical reactions and internal and external mass and heat transfer processes Indeed, interaction between the chemical and transport mechanisms dur-ing 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 ... Biomass Gasification Fixed bed downdraft gasifier Modeling Kinetics Heat and mass transfer a b s t r a c t A two dimensional modeling is developed in the reduction zone of afixed bed downdraft biomass

Ngày tải lên: 01/08/2016, 09:31

... Sarofim, Radiative Transfer, McGraw-Hill, 1967 Incropera and DeWitt, Fundamentals of Heat and Mass Transfer, 5th ed., Wiley, 2002 Kays and Crawford, Convective Heat and Mass Transfer, 3d ed., ... Conduction Heat Transfer, Addison-Wesley,1966 Arpaci, Convection Heat Transfer, Prentice-Hall, 1984 Arpaci, Introduction to Heat Transfer, Prentice-Hall, 1999 Baehr and Stephan, Heat and Mass Trans-fer, ... Conduction: Semi-infinite Plate 5-7 HEAT TRANSFER BY CONVECTION Convective Heat-Transfer Coefficient 5-7 Individual Heat-Transfer Coefficient 5-7 5-1 Heat and Mass Transfer* Hoyt C Hottel, S.M Deceased;

Ngày tải lên: 23/08/2017, 23:24

... radiation heat transfer between a person and the surrounding surfaces at specified temperatures is to be determined in summer and in winter Assumptions 1 Steady operating conditions exist 2 Heat transfer ... rate of heat transfer by convection is Q&conv=hA sΔT =(55W/m2⋅°C)(2×4m2)(80−30)°C=22,000 W Trang 101-68 EES Prob 1-67 is reconsidered The rate of heat transfer as a function of the heat transfer ... Analysis (a) Noting that the heat transfer through the wall is by conduction and the surface area of the wall is A=20ft×10ft=200ft2, the steady rate of heat transfer through the wall can be

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

... corresponds to that of heat conduction, whilst mass transfer in a flowing fluid, known for short as convective mass transfer corresponds to convective mass transfer. Mass transfer by diffusion and convection ... only sorts of mass transfer. Radiative heat transfer has no corresponding mass transfer process. 1.4.1 Diffusion The calculation of mass transfer by diffusion requires several definitions and rela- tionships ... time. Further important investigations included heat transfer in film condensation, cross current heat transfer and the analogy between heat and mass transfer in evaporation. 76 1 Introduction....

Ngày tải lên: 02/04/2014, 15:27

... The symbols dQ and dW represent differential heat transfer and work done, respectively. The differential operator, d, is used as both heat transfer and work are path functions and the evaluation ... Molecular Mass Transfer 399 24.2 The Diffusion Coefficient 407 24.3 Convective Mass Transfer 428 24.4 Closure 429 25. Differential Equations of Mass Transfer 433 25.1 The Differential Equation for Mass ... 380 23.10 Radiant Heat Transfer Between Gray Surfaces 381 23.11 Radiation from Gases 388 23.12 The Radiation Heat- Transfer Coefficient 392 23.13 Closure 393 24. Fundamentals of Mass Transfer 398 24.1...

Ngày tải lên: 02/04/2014, 15:51