Concerning the exchanger, Q kcal/h represents the quantity of heat for exchange

• W:The quantity of flow for low-temperature side fluid(kg/h)
• i1,i2:Quantity of heat for the entry and exit of low-temperature fluid(kcal/kg)
• W':The quantity of flow for high-temperature side fluid(kg/h)
• i'1, i'2:The quantity of heat for exit and entry of high-temperature side fluid(kcal/kg)
• A:Area of valid heat transfer(m²)
• θm=Logarithm average temperature difference(°C)
• θ1=Whatever direct current or reverse current, the part of large temperature difference(°C)
• θ2=Whatever direct current or reverse current, the part of little temperature difference(°C)
• K=The flow rate of thermos(kcal/m² h°C)

The general value of K is shown as follow

流體在水平管外部時

流體在垂直管外部時

• h=熱傳導係數 kcal/m² hr°C
• Cp=Constant-Pressure Specific Heat of Fluid kcal/kg°C
• λ=Thermal Conductivity of Fluid kcal/mhr°C
• ρ=Fluid Density kg/m³
• β=Coefficient of Expansion of Fluid 1/°C
• μ=Fluid Viscosity kg/mhr
• g=Acceleration of Gravity m/ hr²
• Δt=Temperature Difference between Fluid Itself and the Side of Conduction of Heat °C

Fluid flows out of the pipe

intricate Permutation

Square Permutation

• d=external diameter of pipe m
• h=Thermal Conductivity of Border Membrane kcal/m²hr°C
• υ=Average Speed of Fluid m/hr
• λ=Average Thermal Conductivity of Fluid kcal/mhr°C
• μ=Average Viscosity of Fluid kg/mhr
• ρ=Average Density of Fluid kg/m³

　　　　空氣流中之管群熱傳導係數，平均溫度60°C方格式排列之場合，適用於蒸氣、氧氣、氮氣、烟道氣體亦可得相當近似值