Conduction-Rectangular Coordinates

CONDUCTION HEAT TRANSFER Heat Transfer Solution: Using Equation 2-4: Q k A � � � � � � DT Dx Solving for DT: DT Q^� � � � � � Dx k A � � � � � � 1000^Btu hr � � � � � � 1 12 ft � � � � � � 0.12 Btu hr ft °F 1 ft² DT 694°F Example: A concrete floor with a conductivity of 0.8 Btu/hr-ft-°F measures 30 ft by 40 ft with a thickness of 4 inches. The floor has a surface temperature of 70°F and the temperature beneath it is 60°F. What is the heat flux and the heat transfer rate through the floor? Solution: Using Equations 2-1 and 2-4: Q Q A k^� � � � � � DT Dx � � � � � � 0.8 Btu hr ft °F � � � � � � 10°F 0.333 ft 24 Btu hr ft² HT-02 Page 8 Rev. 0