# Heat Transfer by Conduction through a Plane Wall

## Heat Transfer by Conduction through a Plane Wall Formula |
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\(\large{ Q_c = \frac {- k \; A_c \; \left( T_2 \;-\; T_1 \right) } { l } }\) | ||

Symbol |
English |
Metric |

\(\large{ Q_c }\) = heat transfer by conduction | \(\large{\frac{Btu}{hr}}\) | \(\large{W}\) |

\(\large{ A_c }\) = area cross-section | \(\large{in^2}\) | \(\large{mm^2}\) |

\(\large{ T_1 }\) = temperature of one surface of the wall | \(\large{F}\) | \(\large{K}\) |

\(\large{ T_2 }\) = temperature of the other surface of the wall | \(\large{F}\) | \(\large{K}\) |

\(\large{ k }\) = thermal conductivity | \(\large{\frac{Btu-ft}{hr-ft^2-F}}\) | \(\large{\frac{W}{m-K}}\) |

\(\large{ l }\) = thickness of material | \(\large{in}\) | \(\large{mm}\) |

## Heat Transfer by Conduction through a Cylindrical Wall formula |
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\(\large{ Q_c = \frac { 2 \; \pi \; k \; l \; \left( T_1 \;-\; T_2 \right) } { ln \; \left( \frac {r_2 }{ r_1 } \right) } }\) | ||

Symbol |
English |
Metric |

\(\large{ Q_c }\) = heat transfer by conduction | \(\large{\frac{Btu}{hr}}\) | \(\large{W}\) |

\(\large{ A_c }\) = area cross-section | \(\large{in^2}\) | \(\large{mm^2}\) |

\(\large{ \pi }\) = Pi | \(\large{3.141 592 653 ...}\) | |

\(\large{ r_1 }\) = radius of one surface of the wall | \(\large{in}\) | \(\large{mm}\) |

\(\large{ r_2 }\) = radius of the other surface of the wall | \(\large{in}\) | \(\large{mm}\) |

\(\large{ T_1 }\) = temperature of one surface of the wall | \(\large{F}\) | \(\large{K}\) |

\(\large{ T_2 }\) = temperature of the other surface of the wall | \(\large{F}\) | \(\large{K}\) |

\(\large{ k }\) = thermal conductivity | \(\large{\frac{Btu-ft}{hr-ft^2-F}}\) | \(\large{\frac{W}{m-K}}\) |

\(\large{ l }\) = thickness of material | \(\large{in}\) | \(\large{mm}\) |

Tags: Heat Transfer Heat