TITLE.PM5

798 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-1.pm5 (i)The rate of removal of heat, Q : Q = At t h L k L k L kh i o A A B B ...

HEAT TRANSFER 799 dharm \M-therm\Th15-1.pm5 The rate of heat transfer per unit area of the furnace wall, q = hhf (thf – t 1 ) = ...

800 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 Let r 1 , r 2 = Inner and outer radii ; t 1 , t 2 = Temperature of inne ...

HEAT TRANSFER 801 dharm \M-therm\Th15-2.pm5 kA = Thermal conductivity of the inside layer A, kB = Thermal conductivity of the ou ...

802 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 ∴ Q = 2 11 11 1 21 3 2 3 πLt t hr k rr k rr hr hf cf hf ABcf () . ln ( ...

HEAT TRANSFER 803 dharm \M-therm\Th15-2.pm5 Example 15.10. Hot air at a temperature of 65°C is flowing through a steel pipe of 1 ...

804 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 = 16964 6 0 2777 2 8881 0 7192 0 5208 . ....++ + = 3850.5 W i.e., Rate ...

HEAT TRANSFER 805 dharm \M-therm\Th15-2.pm5 0.989 L × 10^3 = 2 150 20 1 100 0 06 008 006 42 008 08 1 30 3 3 πL r r () . ln(. /. ...

806 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 15.2.8.2. Heat conduction through a composite sphere Considering Fig. 1 ...

HEAT TRANSFER 807 dharm \M-therm\Th15-2.pm5 If there are n concentric spheres then the above equation can be written as follows ...

808 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 15.2.9. Critical thickness of insulation 15.2.9.1. Insulation-General a ...

HEAT TRANSFER 809 dharm \M-therm\Th15-2.pm5 ho = Heat transfer coefficient at the outer surface of the insulation, and k = Therm ...

810 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 added, the heat loss rate is still greater for the solid cylinder. This ...

HEAT TRANSFER 811 dharm \M-therm\Th15-2.pm5 Solid sphere Insulation t hO 1 k r 1 r– r 21 r 2 tair Fig. 15.27 Example 15.13. A sm ...

812 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 Case II : The heat flow through an insulated wire when critical thickne ...

HEAT TRANSFER 813 dharm \M-therm\Th15-2.pm5 ( ) Physical configurationa Fluid flow tf ts t<tsf Q Surface ts tf () 1 hA Q ( ) ...

814 ENGINEERING THERMODYNAMICS dharm \M-therm\Th15-2.pm5 Solution. Diameter of the wire, d = 1.5 mm = 0.0015 m Length of the wir ...

HEAT TRANSFER 815 dharm \M-therm\Th15-2.pm5 Let us first determine the type of the flow m = ρAu = 983.2 × π 4 × (0.02)^2 × u = 0 ...

dharm \M-therm\Th15-3.pm5 816 ENGINEERING THERMODYNAMICS (i) Direct contact heat exchangers. In a direct contact or open heat ex ...

dharm \M-therm\Th15-3.pm5 HEAT TRANSFER 817 (b) Recuperators : ‘Recuperator’ is the most important type of heat exchanger in whi ...