PART 3 INTRODUCTION TO ENGINEERING HEAT TRANSFER
HT7 ∂ ∂−() −= f TT kA L 2 AB TA TB 0. () In equation (), k is a proportionality factor that is a function of the material and the temperature, A is the crosssectional area and L is the length of the bar. In the limit for any temperature difference ∆T across a length ∆x as both L, T A .