TITLE.PM5

778 15.1. Modes of Heat Transfer ‘‘Heat transfer’’ which is defined as the transmission of energy from one region to another as ...

HEAT TRANSFER 779 dharm \M-therm\Th15-1.pm5 In liquids, the mechanism of heat is nearer to that of gases. However, the molecules ...

780 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 Mathematically, it can be represented by the equation : Q ∝ A. dt dx wh ...

HEAT TRANSFER 781 dharm \M-therm\Th15-1.pm5 It follows from eqn. (15.1) that materials with high thermal conductivities are good ...

782 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 where, k 0 = Thermal conductivity at 0°C, and β= Temperature coefficien ...

HEAT TRANSFER 783 dharm \M-therm\Th15-1.pm5 By comparing eqns. (15.4) and (15.5), we find that I is analogus to, Q, dV is analog ...

784 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 If the directional characteristics of a material are equal/same, it is ...

HEAT TRANSFER 785 dharm \M-therm\Th15-1.pm5 = ∂ ∂ ∂ ∂ L NM O QP + ∂ ∂ ∂ ∂ L N M O Q P + ∂ ∂ ∂ ∂ L NM O x QP k t x dx dy dz d y k ...

786 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 conductivity k or a low value of heat capacity ρ.c. A low value of heat ...

HEAT TRANSFER 787 dharm \M-therm\Th15-1.pm5 15.2.5. Heat conduction through plane and composite walls 15.2.5.1. Heat conduction ...

788 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 But, dt dx d dx tt L xt tt L = F − HG I KJ + L N M O Q P= 21 − 1 21 ∴ Q ...

HEAT TRANSFER 789 dharm \M-therm\Th15-1.pm5 Since the quantity of heat transmitted per unit time through each slab/layer is same ...

790 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 In order to solve more complex problems involving both series and paral ...

HEAT TRANSFER 791 dharm \M-therm\Th15-1.pm5 t 1 t 2 hcf hhf Hot fluid film Q Q thf 1 Metal wall Cold fluid film tcf 2 L thf t 1 ...

792 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 A B Fire brick Insulation t = 1325 C 1 º t = 1200 C 2 º (^123) L = 320 ...

HEAT TRANSFER 793 dharm \M-therm\Th15-1.pm5 or 1300 1190 2 6 25 105 ..LLLAAA+− = or^1300 2506 105 − = . LLAA or 1300 LA = 105 (2 ...

794 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 or 0.1428 + 0.0833 = 0.2 [0.1428 + 0.0833 + 15.385 x] or 0.2261 = 0.2 ( ...

HEAT TRANSFER 795 dharm \M-therm\Th15-1.pm5 or 400 = 1110 L k L k L k L k A A B B C C D D +++ or 400 = 02 1110 152 1000 0138 0 0 ...

796 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 Q Q 1 2 3 4 A C D B 3 cm 8 cm 5 cm 3 cm 7 cm Q Q Rth–B Rth–C t 1 Rth–A ...

HEAT TRANSFER 797 dharm \M-therm\Th15-1.pm5 ∴ U =^1 01006. = 9.94 W/m^2 °C ∴ q = 9.94 × 1 × (95 – 15) = 795.2 W/m^2. (Ans.) (ii) ...