Heat Transfer: Exercises 9 Introduction Example 1 4 An electronic component dissipates 0 38 Watts through a heat sink by convection and radiation (black body) into surrounds at 20oC What is the surface temperature of the heat sink if the convective heat transfer coefficient is 6 W/m2 K, and the heat sink has an effective area of 0 001 m2
book is primarily concerned with convective heat transfer Essentials of mass transfer are also covered The mass transfer material and prob-lems are presented such that they can be easily skipped, should that be preferred The book is richly enhanced by exercises and end-of-chapter problems Solutions are available for quali?ed instructors
Heat Transfer: Exercises 9 Introduction Example 1 4 An electronic component dissipates 0 38 Watts through a heat sink by convection and radiation (black body) into surrounds at 20oC What is the surface temperature of the heat sink if the convective heat transfer coefficient is 6 W/m2 K, and the heat sink has an effective area of 0 001 m2
Steady Heat Transfer February 14, 2007 ME 375 – Heat Transfer 3 13 Parallel Resistances (T? = T surr) Rtotal Rconv Rrad 1 1 1 = + s conv s rad total A h A h R = + 1 Tsurr T? = • Define total heat transfer coefficient, h total conv rad s total total h h A R h = = + Figure 3-5 1 from Çengel, Heat and Mass Transfer 14 Combined Modes
The Colburnanalogy permits the prediction of heat transfer performance from friction factor results A similar analogy between heat and mass transfer was proposed by Chilton and Colburn (2) This analogy has been used widely by chemical engineers in mass transfer, even though predictions obtained using it are not always very good
Figure 3 6: Wall with convective heat transfer The second heat transfer process is convection, or heat transfer due to a flowing fluid exercise for the reader
Convective heat transfer : solved problems / Michel Favre-Marinet, Sedat Tardu at the beginning of each chapter and then to propose a series of exercises or
of heat conduction, convection, and radiation as we proceed to look at each in some detail The very important thing that we learn from this exercise in dimen-
OVERALL HEAT TRANSFER COEFFICIENT Heat losses from a coffee cup glass Introduction You should be able to perform this exercise in your kitchen using the Heat transfer occurs in three ways: conduction, convection and radiation
Heat transfer supplements the first and second principles of thermodynamics used to establish energy transfer rate Convection heat transfer depends on the viscosity and the thermal properties of the fluid (k, cp, ρ); Viscosity Exercise 1:
Heat Balance Heat Gain Heat Loss Metabolic heat prod Radiation -exercise Conduction -shivering Convection -thyroxine Evaporation -symp stim -Q10 effect
Thermal energy transfer is heat moving from a warmer object to a cooler object How is Heat Transferred? There are THREE ways heat can move Conduction