chimney guys

1
chimney guys

• flow rate, average heat transfer coefficient,
• and total heat transfer rate

andrew enke steve jensen
2
background

• residential chimneys have problems of smoke flow
  returning into the home
• 1/8 rule minimum cross-sectional area ratio of
  the chimney flue and fireplace opening
• chimney efficiency decreases if chimney height is
  too short or too tall

3
procedure

• grandmas chimney
• H 8.2 m
• D .152 m
• A .0182 m2
• Tm,i 17.8 C
• Tm,0 208 C
• u 1.6 m/s

steves chimney H 3.7 m D .203 m A .0324
m2 Tm,i 23 C Tm,0 223 C u 2.3 m/s
4
results
Grandma's Chimney Steve's Chimney
mdot (kg/s) 0.0264 0.0676
ReD 9860.2800 18898.8700
xfdt (m) 52.0688 133.0647
Xfdh (m) 75.1353 192.0125
Nu 7.8692 15.1344
hbar (W/m2-K) 1.6885 2.4355
q (W) 5088.3287 1368.7902
q" (W/m2) 11.0705 586.2287
Q (m3/s) measured 0.0301 0.0437
Q (m3/s) predicted 0.0292 0.0746
5
conclusion

• grandmas chimney
• hbar(W/m2-K) 1.6885
• q (W) 5088.3287
• q" (W/m2) 11.0705
• Q (m3/s) measured 0.0301
• Q (m3/s) predicted 0.0292

• steves chimney
• hbar(W/m2-K) 2.4355
• q (W) 1368.7902
• q" (W/m2) 586.2287
• Q (m3/s) measured 0.0437
• Q (m3/s) predicted 0.0746