In the calculation of Reynold’s Number for the Friction factor of the annulus tube, which is the correct formula for equivalent diameter De?

\(\frac{4×(D_{oi}^2 – D_{io}^2)×\frac{π}{4}}{π(D_{io})}\)

\(\frac{4×(D_{io}^2 – D_{oi}^2)×\frac{π}{4}}{π(D_{io})}\)

\(\frac{4×(D_{oi}^2 – D_{io}^2)×\frac{π}{4}}{π(D_{io}+D_{oi})}\)

\(\frac{4×(D_{io}^2 – D_{oi}^2)×\frac{π}{4}}{π(D_{io}+D_{oi})}\)

Consider we have a Double Pipe Heat Exchanger, with the inner tube of Outer diameter 20mm (thickness 2mm) and outer tube of inner diameter 30mm. We have two fluids A & B, both of density 990 Kg/m3, we desire to have their flow rates as 15m/s and 21m/s respectively, friction factor of 0.0096 and 5 hairpins of length 0.4 metre. If the maximum pressure drop allowed is 10psi, is the setup suitable for industrial use?

No, since pressure drop is less than specified

Yes, since pressure drop is less than specified

No, since pressure drop is more than specified

Yes, since pressure drop is more than specified

1.	Consider we have a Double Pipe Heat Exchanger, with the inner tube of diameter 20mm (neglect thickness) and outer tube of diameter 30mm. We have two fluids A & B (both with viscosity 2.5×10-5Pa-s), we desire to have their flow rates as 15 Kg/s and 21 Kg/s respectively. What is the Friction Factor (F) for this setup for the annulus pipe?
A.	0.0086
B.	0.0103
C.	0.086
D.	0.00103
Answer» C. 0.086

2.	In the calculation of Reynold’s Number for the Friction factor of the annulus tube, which is the correct formula for equivalent diameter De?
A.	\(\frac{4×(D_{oi}^2 – D_{io}^2)×\frac{π}{4}}{π(D_{io})}\)
B.	\(\frac{4×(D_{io}^2 – D_{oi}^2)×\frac{π}{4}}{π(D_{io})}\)
C.	\(\frac{4×(D_{oi}^2 – D_{io}^2)×\frac{π}{4}}{π(D_{io}+D_{oi})}\)
D.	\(\frac{4×(D_{io}^2 – D_{oi}^2)×\frac{π}{4}}{π(D_{io}+D_{oi})}\)
Answer» D. \(\frac{4×(D_{io}^2 – D_{oi}^2)×\frac{π}{4}}{π(D_{io}+D_{oi})}\)

3.	Consider we have a Double Pipe Heat Exchanger, with the inner tube of Outer diameter 20mm (thickness 2mm) and outer tube of inner diameter 30mm. We have two fluids A & B, both of density 990 Kg/m3, we desire to have their flow rates as 15m/s and 21m/s respectively, friction factor of 0.0096 and 5 hairpins of length 0.4 metre. If the maximum pressure drop allowed is 10psi, is the setup suitable for industrial use?
A.	No, since pressure drop is less than specified
B.	Yes, since pressure drop is less than specified
C.	No, since pressure drop is more than specified
D.	Yes, since pressure drop is more than specified
Answer» D. Yes, since pressure drop is more than specified

4.	Consider we have a Double Pipe Heat Exchanger, with the inner tube of Outer diameter 20mm (thickness 2mm) and outer tube of inner diameter 30mm. We have two fluids A & B, both of density 990 Kg/m3, we desire to have their flow rates as 15m/s and 21m/s respectively, friction factor of 0.00096 and 5 hairpins of length 0.4 metre. What is the value of Pressure drop for the inner tube?
A.	6atm
B.	2atm
C.	5atm
D.	4atm
Answer» B. 2atm

5.	When we calculate the pressure drop ΔP = \(\frac{XFL}{D} \frac{v^2}{2g}\)×ϸ, what is the value X?
A.	2
B.	4
C.	5
D.	8
Answer» C. 5

6.	Consider we have a Double Pipe Heat Exchanger, with the inner tube of Outer diameter 20mm(thickness 2mm) and outer tube of inner diameter 30mm. We have two fluids A & B, both of density 990 Kg/m3, we desire to have their flow rates as 15m/s and 21 m/s respectively, friction factor of 0.00096 and length of the tube as 1metre. What is the value of Pressure drop for the inner tube?
A.	25 KPa
B.	20 KPa
C.	27 KPa
D.	35 KPa
Answer» D. 35 KPa

7.	Consider we have a Double Pipe Heat Exchanger, with the inner tube of Outer diameter 20mm (thickness 2mm) and outer tube of inner diameter 30mm. We have two fluids A & B, we desire to have their flow rates as 15 m/s and 21 m/s respectively, friction factor of 0.0096 and length of the tube as 1metre. What is the value of hfs for the inner tube?
A.	27.6m
B.	15m
C.	21.12m
D.	22m
Answer» B. 15m

8.	Consider we have a Double Pipe Heat Exchanger, with the inner tube of diameter 20mm (neglect thickness) and outer tube of diameter 30mm. We have two fluids A & B (both with viscosity 2.5×10-5Pa-s), we desire to have their flow rates as 15Kg/s and 21Kg/s respectively. What is the Friction Factor (F) for this setup for the inner pipe?
A.	0.0086
B.	0.086
C.	0.0068
D.	0.068
Answer» B. 0.086