(a) Steam in a heating system flows through tubes whose outer diamete…

Question

(a) Steam in a heating system flows through tubes whose outer diameter is $D_1 = 3 \text{ cm}$ and whose walls are maintained at a temperature of $120^{\circ}\text{C}$. Circular aluminum fins ($k = 180 \text{ W/m }^{\circ}\text{C}$) of outer diameter $D_2 = 6 \text{ cm}$ and constant thickness $t = 2 \text{ mm}$ are attached to the tube. The space between the fins is $3 \text{ mm}$, and thus there are 200 fins per meter length of the tube. Heat is transferred to the surrounding air at $T_{\infty} = 25^{\circ}\text{C}$, with a combined heat transfer coefficient of $h = 60 \text{ W/m}^2\text{ }^{\circ}\text{C}$. Determine the increase in heat transfer from the tube per meter of its length as a result of adding fins. [10]

(b) Explain how fins can increase the rate of heat transfer. Mention the most common types of fins and sketch them. Give some practical examples of fins. [10]

Related pages

• Extended surface heat transfer in case of long fin, fin with insulated tip and short fin — topic
• HEAT TRANSFER syllabus