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