Q.

The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity)

• AQ = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁)
• BQ = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)]
• CQ = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁)
• DQ = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁)