BASIC HEAT TRANSFER RELATIONSHIPS

1. Conductive Heat Transfer

   1. Defining equation

      
      

   2. Temperature field equation in rectangular and cylindrical coordinates

      
      

   3. Thermal conductive resistance for one-dimensional heat flow in a rectangular slab, cylinder and a sphere.

      
      

2. Thermal Radiation

   1. Black body emission behavior

      1. Hemispherical radiation intensity-Stefan Boltzmann law

         
         

      2. Wave length intensity-Planck's distribution law

         
         

      3. Wave length of most intense radiation-Wein's displacement law

         
         

      4. Directional radiation intensity-Lambert's cosine law

         
         

      5. Radiation exchange between black, isothermal surfaces separated by a non-absorbing medium

         
         

   2. Grey body behavior

      1. Definition

         
         

      2. Fractional distribution of incident radiant energy

         
         

      3. Circuit network for grey body enclosure composed of isothermal surfaces

         

3. Convective Heat Transfer

   1. Defining equation

      
      

   2. Natural convection, t _fluid is defined as t _surrounding bath

      
      

      Resulting groups are

      
      

   3. Unestablished, forced convective heat transfer, t _fluid is defined as t _{free stream}

      
      

   4. Established forced convection in closed conduits, t _fluid is defined as

      
      

   5. Convective resistance for uniform convective coefficient

      
      

4. Heat flow rate for parallel or counter flow heat exchangers assuming uniform fluid properties and heat transfer coefficients and transverse heat transfer only

   
   

   where ?t _a and ?t _b are temperature differences at opposite ends of the exchanger.

   If ?t _a, ?t _b are not known for exchanger, use heat exchanger effectiveness concept

   
   

   (See reference for graphs of ? versus )