international journal of heat and mass transfer pdf

... Dimensions and thermal conductivities of a heater and a finned sleeve Convectionconditions on the sleeve surface FIND: (a) Heat rate per unit length, (b) Generation rate and centerline temperature of heater, ... and we’d expect that grid size might influencethe accuracy of the results Convection heat transfer to the inner surface is and the agreement with results of the coarse grid is excellent The heat ... spacing and control volume length in the x direction are both ∆x The uniform cross-sectional area and fin perimeter are Ac and P, respectively The heat transfer process on the control surfaces, q1 and

Ngày tải lên: 08/08/2014, 17:20

... thickness and thermal conductivity of steel tubes Temperature of steamflowing through the tubes Thermal conductivity of insulation and emissivity of aluminum sheath.Temperature of ambient air and surroundings ... 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 ... thickness and diameter of stainless steel tube Inner and outer fluid temperaturesand convection coefficients FIND: (a) Heat gain per unit length of tube, (b) Effect of adding a 10 mm thick layer of

Ngày tải lên: 08/08/2014, 17:20

... 120 s) and T(0.15 m, 120s) using the finite-element software FEHT for a surface emissivity of 0.94 and (b) Plot the temperature histories for x = 0, 150 and 600 mm, andexplain key features of your ... 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 ... With a time increment of ∆t = 5 s, obtain values of Tm for the first 45s of elapsed time; determine the corresponding heat fluxes at theboundaries; and (d) Determine the effect of mesh size by repeating

Ngày tải lên: 08/08/2014, 17:20

... conductivity and emissivity of Nichrome wire Electricalcurrent Temperature of air flow and surroundings Velocity of air flow. (a) Surface and centerline temperatures of the wire, (b) Effect of flow ... diameter, and properties of heating element Velocityand temperature of air in cross flow. (a) Steady-state temperature, (b) Time to come within 10°C of steady-state temperature (1) Uniform heater ... Rate of heat transfer per unit length for the fluids: atmospheric air and saturated water, andengine oil, for velocity V = 5 m/s, using the Churchill-Bernstein correlation, and (b) Compute and

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 ... conductivity and inner and outer diameters of plastic pipe Volumetric flow rate and inlet and outlet temperatures of air flow through pipe Convection coefficient and temperature of water.FIND: ... 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

... Overall heat transfer coefficient, U, for the HXer, outlet temperature of cooling water, Tc,o,and condensation rate of the steam m h; and (b) Compute and plot Tc,o and m h as a function of thewater ... 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 ... Counterflow, concentric tube heat exchanger undergoing test after service for an extended period of time; surface area of 5 m2 and design value for the overall heat transfer coefficient of Ud = 38 W/m2⋅K

Ngày tải lên: 08/08/2014, 17:20

... 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 FIND: ... part (a) and found theseresults 2 Trang 21PROBLEM 12.91KNOWN: Diameter and initial temperature of copper rod Wall and gas temperature. FIND: (a) Expression for initial rate of change of rod temperature, ... sample of reflectivity, ρλ, and diameter, D, is irradiated with an isothermal enclosureat Tf FIND: (a) Absorptivity, α, of the sample with prescribed ρλ, (b) Emissivity, ε, of the sample, (c) Heatremoved

Ngày tải lên: 08/08/2014, 17:20

... Rate of heat transfer to tube without ash deposit, (b) Rate of heat transfer with an ash deposit of. .. cond,o = 10 C + 6.14 × 10 3 W × 1603 K / W = −0.2°C Using these values of ... system, (b) Temperature of outer surface Ts,o and heat loss q′′ for each system and prescribed conditions, (c) Effect of. .. and becomes negative (heat transfer from the surface) ... temperature and emissivity of boiler tube Thermal conductivity and emissivity of ash deposit Convection coefficient and temperature of gas flow over the tube Temperature of surroundings

Ngày tải lên: 08/08/2014, 17:20

... heat transfer with liquids and gases See Table 1.1 Trang 16KNOWN: Dimensions of a cartridge heater Heater power Convection coefficients in air and water at a prescribed temperature FIND: Heater ... 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 ... yield the Trang 37KNOWN: Blood inlet and outlet temperatures and flow rate Dimensions of tubing FIND: Required rate of heat addition and estimate of kinetic and potential energy changes ASSUMPTIONS:

Ngày tải lên: 13/09/2018, 13:35

... and heat rates at ends of shaft The difference in heat rates, qx(0) > qx(L), is due to heat losses qA from the side of the shaft COMMENTS: Heat loss from the side requires the existence of ... law and knowledge of the heat rate dependence upon the x-coordinate Give it a try! Trang 15KNOWN: Dimensions of and temperature difference across an aircraft window Window materials and cost of ... dimensional heat transfer in samples, (2) Constant properties, (3) egligible heat loss through insulation, (4) Negligible heater mass N ANALYSIS: Consider a control volume about the samples and heater,

Ngày tải lên: 13/09/2018, 13:35

... Stainless Steel SandwichLiquid layer 4SandwichLiquid layer 4SandwichLiquid layer 3SandwichLiquid layer 3SandwichLiquid layer 2SandwichLiquid layer 2 Liquid layer 5 SandwichLiquid layer 1SandwichLiquid ... Temperatures and convection coefficients associated with air at the inner and outer surfaces of a rear window FIND: (a) Inner and outer window surface temperatures, Ts,i and Ts,o, and (b) Ts,i and Ts,o ... analysis, Ts,i and Ts,o have been computed and plotted as a function of the outside air temperature, T∞,o, for outer convection coefficients of ho = 2, 65, and 100 W/m2⋅K As expected, Ts,i and Ts,o

Ngày tải lên: 13/09/2018, 13:36

... the amount of heat dissipated by radiation to space Trang 29KNOWN: Initial and final temperatures of a niobium sphere Diameter and properties of the sphere emperature of surroundings and/or gas ... Convection coefficient and freestream temperature of plasma gas Melting point and latent heat of fusion of Co F IND: Times required to reach melting and to achieve complete melting of Co SCHEMATIC: ... properties of chip, solder and ubstrate Temperature and convection coefficient of heating agent s FIND: (a) Time constants and temperature histories of chip, solder and substrate when heated by an air

Ngày tải lên: 13/09/2018, 13:36

... superior heat transfer fluid, while air is the least effective COMMENTS: The figure of merit indicates that heat transfer is enhanced by fluids of large k, large β and small values of α and ν Trang ... value of the heat transfer coefficient Trang 3PROBLEM 9.3 K NOWN: Form of the Nusselt number correlation for natural convection and fluid properties F IND: Expression for figure of merit FN and ... surfaces will coalesce and heat transfer will decrease If fins are too far apart, the surface area becomes too small and heat transfer decreases Sop≈δx=H From Fig 9.4, the edge of boundary layer

Ngày tải lên: 13/09/2018, 13:36

... 3 to 5 μm and 8 to 14 μm FIND: (a) Band-emission factors for each of the spectral regions, 3 to 5 μm and 8 to 14 μm, for temperatures of 300 and 900 K, (b) Calculate and plot the band-emission ... and emitted energy assuming blackbody behavior Trang 21K NOWN: Diameter and temperature of burner Temperature of ambient air Burner efficiency FIND: (a) Radiation and convection heat rates, and ... the sensitive spectral region of a solid-state (photoconductive type) heat-flux gage, and (c) Calculate and plot the heat fluxes for each of the gages as a function of the furnace temperature for

Ngày tải lên: 13/09/2018, 13:37

... water-ice mixture. Mass and specific heat of reference sphere. FIND: Specific heat of the test sphere of known mass. SCHEMATIC: ASSUMPTIONS: (1) Spheres are of equal diameter, ... Electrical heater is perfectly insulated from dryer wall, (3) Heater and switch are isothermal at T set , (4) Negligible heat transfer from sides of heater or switch, (5) Switch surface, A s , loses heat ... KNOWN: Power consumption, diameter, and inlet and discharge temperatures of a hair dryer. FIND: (a) Volumetric flow rate and discharge velocity of heated air, (b) Heat loss from case. SCHEMATIC:...

Ngày tải lên: 02/04/2014, 15:52

... COMBINED MODES OF HEAT TRANSFER Previous sections treated each mode of heat transfer separately. But in practice all the three modes of heat transfer can occur simultaneously. Additionally heat generation ... FUNDAMENTALS OF HEAT AND MASS TRANSFER In this chapter only simple cases will be dealt with and the determination of F will be taken up in the chapter on radiation. The concept of h r is convenient, ... blank type and true or false type questions are provided to test the understanding of the basic principles. Author PREFACE vii VED c-4\n-demo\damo2-3 74 FUNDAMENTALS OF HEAT AND MASS TRANSFER 0.1...

Ngày tải lên: 08/04/2014, 10:55

... value of the heat rate. PROBLEM 1.39 KNOWN: Power consumption, diameter, and inlet and discharge temperatures of a hair dryer. FIND: (a) Volumetric flow rate and discharge velocity of heated ... Electrical heater is perfectly insulated from dryer wall, (3) Heater and switch are isothermal at T set , (4) Negligible heat transfer from sides of heater or switch, (5) Switch surface, A s , loses heat ... KNOWN: Dimensions, thermal conductivity and surface temperatures of a concrete slab. Efficiency of gas furnace and cost of natural gas. FIND: Daily cost of heat loss. SCHEMATIC: ASSUMPTIONS: ...

Ngày tải lên: 08/08/2014, 17:20

... components Heat output Fig. 9 Micro heat pipe [54] Two-Phase Flow and Heat Transfer in Micro-Channels 57 17. In, S., Jeong, S.: Flow boiling heat transfer characteristics of R123 and R134a in ... knowledge of heat transfer mechanisms at different conditions. Investigations on flow boiling heat transfer in literature have revealed numbers of criteria of system classification, flow instabilities and ... Microchannel Heat Sinks. J. Heat Transf. 129(10), 1341–1351 (2007) 37. Brutin, D., Tadrist, L.: Pressure drop and heat transfer analysis of flow boiling in a minichannel: influence of the inlet...

Ngày tải lên: 31/03/2014, 16:20

... 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 of integrals ... 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 ... to Momentum Transfer Chapter 4 Conservation of Mass: Control-Volume Approach The initial application of the fundamental laws of fluid mechanics involves the law of conservation of mass. In this...

Ngày tải lên: 02/04/2014, 15:51