1. EXTENDED SURFACE HEAT TRANSFER EXPERIMENT No. 8 CONVECTION HEAT TRANSFER by DOWEL S HEAT EXCHANGER (PIN FIN ) Part B: Forced Convection EXTENDED SURFACE HEAT TRANSFER EXPERIMENT No. 8 CONVECTION HEAT TRANSFER by DOWEL S HEAT EXCHANGER (PIN FIN ) Part B: Forced Convection

2. Procedure of the Experiment: Forced Convection The constant temperature bath is adjusted to 60° C and started up at least an hour before the start of the lab session. Measure the free convection temperature profile, i.e. with the wind tunnel switched off. Record this temperature profile. Start the blower and adjust the difference of level in the manometer with the help of gate valve (25 cm 3 /s). Allow the fin to reach steady state. Record the temperature profile at time interval of 300s. Repeat Steps 5- 6 for the wind tunnel counter settings of (50 - 250) cm 3 /s, in increments of 25 cm 3 /s.

3. OBSERVATION TABLE

4. Sample of Calculation 1. Specify the case of the Fin 2. T tip = 42.8 C T tip > T ∞ 3. T ∞ =24.94 C The case of the Fin is A TxTx X (mm) 56.96 0 50.12 12.5 44.26 62.5 42.3 112.5

5. Case of the fin in each stap Fin typeT tip T∞T∞ Step A42.824.961 2 3 4 5 6 7 8 9 10

6. Evaluate the Film Temperature Tw=( T3+T4+T5)/3 and Tf=(T∞+Tw)/2 TfTwT∞Step 35.2545.5624.961 2 3 4 5 6 7 8 9 10

7. Properties of air at 1atm. V m^2/secPrK W/m.C Temp. K 15.69 E-06 0.7080.02624300 20.76 E-060.6970.03003350 K(308.25) =K(300) +8.25/50(K(350) - K(300) = 0.026865W/m.C Pr(308.25) =Pr(300) +8.25/50(Pr(350) - Pr(300) = 0.70618 v(308.25) =v(300) +8.25/50(v(350) - v(300) = 16.526 E-06 m^2/sec Prw =Pr(300) +18.56/50(Pr(350) - Pr(300) = 0.70391 Where Tw= 318.56 C

8. Evaluate of h W/m^2.C Re= u.d/v u=Q/A = 20.08/(12*15)= 0.1115cm/s =.001115m/s Re=(.001115*.01)/16.525E-06 = 0.675 From Table 6-6 C= 0.9 and n= 0.4 Nu= 0.678 h= 0.678*0.026865/0.01 = 1.821 W/m^2.C m= (h.P/k A c )^0.5 = (1.821* 0.00397/(204* Ac=7.854×10^-5))^0.5 = 0.6681 h/mk = 1.821/(0.6681*204)= 0.013361 P= 0.003927 m Ac=7.854× 〖 10 〗 ^(-5) m^2 k= 204 W/m. C Δx= 0.0125 m

9. Temperature Dimensionless Calculation θ/θ o = θ/θoθ/θo x/L 11 0 0.87870.99920.1 0.60350.99680.5 0.54220.9950.9 0.5570.9951

10. Effectiveness Calculation Heat transfer by Fin = =.0126 W = 1.16 = 0.967