heat and mass transfer cengel 3rd edition book

... 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

... valves are to be heated in a heat treatment section The amount of heat transfer, the average rate of heat transfer, the average heat flux, and the number of valves that can be heat treated daily ... the person and the convection heat transfer coefficient is constant and uniform 3 Heat loss by radiation is negligible Analysis The heat transfer surface area of the person is To lose heat at ... 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

... surface area is called heat flux It is related to the rate of heat q& ∫ = A dA q Q& & 1-9C Energy can be transferred by heat, work, and mass An energy transfer is heat transfer when its ... INTRODUCTION AND BASIC CONCEPTS Thermodynamics and Heat Transfer 1-1C Thermodynamics deals with the amount of heat transfer as a system undergoes a process from one equilibrium state to another Heat transfer, ... is heated from 10°C to 22°C by an electric heater, and some air escapes through the cracks as the heated air in the house expands at constant pressure The amount of heat transfer to the air and

Ngày tải lên: 07/03/2018, 16:28

... Assumptions 1 Heat transfer is steady since there is no change with time 2 Heat transfer is one-dimensional since this two-layer heat transfer problem possesses symmetry about the center line and involves ... Thermal conductivity is constant 4 Heat generation is uniform Analysis (a) Noting that the heat flux and the heat generated will be transferred to the water, the heat transfer coefficient is determined ... for steady one-dimensional heat transfer Assumptions 1 Heat conduction is steady and one-dimensional 2 Thermal conductivity is constant 3 There is no heat generation 4 Heat loss through the upper

Ngày tải lên: 07/03/2018, 16:28

... differences (and thus heat transfer) will exist in the radial and axial directions (but there will be symmetry about the center line and no heat transfer in the azimuthal direction.) 2-9C Yes, the heat ... constant and noting that the heat transfer surface areas of the element for heat conduction in the x and y directions are A x=Δy×1andA y =Δx×1, respectively, and taking the limit as Δx Δy andΔt→0 ... the center of the egg 2-6C Heat transfer to a hot dog can be modeled as two-dimensional since temperature differences (and thus heat transfer) will exist in the radial and axial directions (but

Ngày tải lên: 07/03/2018, 16:28

... be determined for steady one-dimensional heat transfer Assumptions 1 Heat transfer is steady since there is no indication of any changes with time 2 Heat transfer is one-dimensional since there ... be determined for steady one-dimensional heat transfer Assumptions 1 Heat conduction is steady and one-dimensional since there is no change with time and there is thermal symmetry about the ... strip heater is transferred to the container, the heat flux through the outer surface is determined to be 2 2 2 2 2 W/m0.213m)(0.414 W50090.04 Q q s &s &s & Noting that heat transfer

Ngày tải lên: 07/03/2018, 16:28

... overall heat transfer coefficient and heat transfer to decrease 3-101C Effectiveness of a single fin is the ratio of the heat transfer rate from the entire exposed surface of the fin to the heat transfer ... enhance heat transfer from a surface by increasing heat transfer surface area for convection heat transfer However, adding too many fins on a surface can suffocate the fluid and retard convection, and ... solved using EES, and the solution is given below Trang 5Heat Transfer from Finned Surfaces 3-97C Increasing the rate of heat transfer from a surface by increasing the heat transfer surface area

Ngày tải lên: 07/03/2018, 16:28

... resistance to heat transfer through window, and thus the heat transfer rate will be smaller relative to the one which consists of a single 8 mm thick glass sheet 3-14C Convection heat transfer through ... wall is expressed as In steady heat transfer, heat transfer rate to the wall and from the wall are equal Therefore at the outer surface which has convection heat transfer coefficient three times ... the convection and radiation heat transfer coefficients are , the single equivalent heat transfer coefficient is h conv and h rad rad conv h = + when the medium and the surrounding surfaces

Ngày tải lên: 07/03/2018, 16:28

... resistance of the wall and the rate of heat transfer through the wall are to be determined Assumptions 1 Heat transfer is steady since there is no indication of change with time 2 Heat transfer through ... against each other 3-44C Heat transfer through the voids at an interface is by conduction and radiation Evacuating the interface eliminates heat transfer by conduction, and thus increases the ... four sides, and on both sides of the wall The rates of heat transfer through the wall constructed of solid bricks and of bricks with air holes are to be determined Assumptions 1 Heat transfer is

Ngày tải lên: 07/03/2018, 16:28

... subjected to convection and radiation heat transfer at its outer surface The rate of heat transfer and the amount of ice that melts per day are to be determined Assumptions 1 Heat transfer is steady ... kg/m3 and cp = 4180 J/kg.°C Analysis This is a transient heat conduction, and the rate of heat transfer will decrease as the drink warms up and the temperature difference between the drink and ... kg/m3 and cp = 4180 J/kg.°C Analysis This is a transient heat conduction, and the rate of heat transfer will decrease as the drink warms up and the temperature difference between the drink and

Ngày tải lên: 07/03/2018, 16:28

... heat lost from each person’s body by perspiration are to be determined Assumptions 1 Heat transfer is steady 2 Heat transfer is one-dimensional 3 Thermal conductivities are constant 4 Heat transfer ... rate of hat transfer through the wall and temperature drops across the plaster, brick, covering, and surface-ambient air are to be determined Assumptions 1 Heat transfer is steady 2 Heat transfer ... temperature, ρ = 62.2 lbm/ft3 and cp = 0.998 Btu/lbm⋅°F Analysis This is a transient heat conduction problem, and the rate of heat transfer will decrease as the potato cools down and the temperature difference

Ngày tải lên: 07/03/2018, 16:28

... operation with and without a heat sink Assumptions 1 The device and the heat sink are isothermal 2 The thermal properties of the device and of the sink are constant 3 The heat transfer coefficient ... heat conduction 4-7C The heat transfer is proportional to the surface area Two half pieces of the roast have a much larger surface area than the single piece and thus a higher rate of heat transfer ... Analysis The mass of the iron's base plate is kg4155.0)m03.0)( m005.0)( kg/m2770 Noting that only 85 percent of the heat generated is transferred to the plate, the rate of heat transfer to the

Ngày tải lên: 07/03/2018, 16:28

... into boiling water, and temperature measurements are taken at certain time intervals The thermal diffusivity and thermal conductivity of the hot dog and the convection heat transfer coefficient ... start of the cooking and the amount of heat transferred to the hot dog are to be determined Assumptions 1 Heat conduction in the hot dog is one-dimensional since it is long and it has thermal ... of the apples on the final center and surface temperatures and the amount of heat transfer is to be investigated Analysis The problem is solved using EES, and the solution is given below "GIVEN"

Ngày tải lên: 07/03/2018, 16:28

... specified temperatures and the maximum heat transfer are to be determined Assumptions 1 The thermal properties of the valves are constant 2 The heat transfer coefficient is constant and uniform over ... are constant Properties The density and heat of vaporization of the water are ρ = 1000 kg/m3 and hfg = 2490 kJ/kg (Table A-9) Analysis The initial and final masses of the raindrop are kg0000141 ... cooked in an oven The average heat transfer coefficient at the surface of the turkey, the temperature of the skin of the turkey in the oven and the total amount of heat transferred to the turkey

Ngày tải lên: 07/03/2018, 16:28

... cylinder and the top surface as well as the total heat transfer from the cylinder for 15 min of cooling are to be determined Assumptions 1 Heat conduction in the short cylinder is two-dimensional, and ... Assumptions 1 Heat conduction in the ice block is two-dimensional, and thus the temperature varies in both x- and y- directions 2 The thermal properties of the ice block are constant 3 The heat transfer ... h is to be determined Assumptions 1 Heat conduction in the ice block is two-dimensional, and thus the temperature varies in both x- and r- directions 2 Heat transfer from the base of the ice block

Ngày tải lên: 07/03/2018, 16:28

... two-dimensional heat transfer The unknown nodal temperatures and the rate of heat loss from the top surface are to be determined Assumptions 1 Heat transfer through the body is given to be steady and two-dimensional ... matrix equation is to be written and simplified and the rate of heat loss from the tube is to be determined Assumptions 1 Heat transfer from the tube is steady and two-dimensional 2 Thermal conductivity ... two-dimensional heat transfer The unknown nodal temperatures and the rate of heat loss from the bottom surface through a 1-m long section are to be determined Assumptions 1 Heat transfer through

Ngày tải lên: 07/03/2018, 16:28

... q& Assumptions 1 Heat transfer through the wall is given to be steady and one-dimensional, and the thermal conductivity and heat generation to be variable 2 Convection heat transfer at the right ... be steady and one-dimensional, and the thermal conductivity to be constant 2 Convection heat transfer coefficient is constant and uniform 3 Radiation heat transfer is negligible 4 Heat loss ... 1 Heat transfer through the pin fin is given to be steady and one-dimensional, and the thermal conductivity to be constant 2 Convection heat transfer coefficient is constant and uniform 3 Heat

Ngày tải lên: 07/03/2018, 16:28

... 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

... 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