¿Qué aspecto importante debemos conocer en el ámbito del

11–17 A long, thin-walled double-pipe heat exchanger with tube and shell diameters of 1.0 cm and 2.5 cm, respectively, is used t

lana [24]

Answer:

the overall heat transfer coefficient of this heat exchanger is 1855.8923 W/m²°C

Explanation:

Given:

d₁ = diameter of the tube = 1 cm = 0.01 m

d₂ = diameter of the shell = 2.5 cm = 0.025 m

Refrigerant-134a

20°C is the temperature of water

h₁ = convection heat transfer coefficient = 4100 W/m² K

Water flows at a rate of 0.3 kg/s

Question: Determine the overall heat transfer coefficient of this heat exchanger, Q = ?

First at all, you need to get the properties of water at 20°C in tables:

k = 0.598 W/m°C

v = 1.004x10⁻⁶m²/s

Pr = 7.01

ρ = 998 kg/m³

Now, you need to calculate the velocity of the water that flows through the shell:

$v_{w} =\frac{m}{\rho \pi (\frac{d_{2}^{2}-d_{1}^{2} }{4} )} =\frac{0.3}{998*\pi (\frac{0.025^{2}-0.01^{2} }{4}) } =0.729m/s$

It is necessary to get the Reynold's number:

$Re=\frac{v_{w}(d_{2}-d_{1}) }{v} =\frac{0.729*(0.025-0.01)}{1.004x10^{-6} } =10891.4343$

Like the Reynold's number is greater than 10000, the regime is turbulent. Now, the Nusselt's number:

$Nu=0.023Re^{0.8} Pr^{0.4} =0.023*(10891.4343)^{0.8} *(7.01)^{0.4} =85.0517$

The overall heat transfer coefficient:

$Q=\frac{1}{\frac{1}{h_{1} }+\frac{1}{h_{2} } }$

Here

$h_{2} =\frac{kNu}{d_{2}-d_{1}} =\frac{0.598*85.0517}{0.025-0.01} =3390.7278W/m^{2}C$

Substituting values:

$Q=\frac{1}{\frac{1}{4100}+\frac{1}{3390.7278} } =1855.8923W/m^{2} C$

5 0

4 years ago

When two or more simple machines are combined they form

Volgvan

Compound machine is the answer

8 0

3 years ago

A circular bar will be subjected to an axial force (P) of 2000 lbf. The bar will be made of material that has a strength (S) of

schepotkina [342]

Answer:

$n = 2.36$

Explanation:

The stress experimented by the circular bar is:

$\sigma = \left[\frac{2000\, lbf}{\frac{\pi}{4}\cdot (0.5\,in)^{2}}\right]\cdot \left(\frac{1\,kpsi}{1000\,psi} \right)$

$\sigma = 10.186\,kpsi$

The safety factor is:

$n = \frac{24\,kpsi}{10.186\,kpsi}$

$n = 2.36$

5 0

3 years ago

The largest class of errors in software engineering can be attributed to _______.

Ilya [14]

Answer:

improper imput validation

Explanation:

6 0

2 years ago

Casting is usually performed in • Industries • Furnaces • Foundries • Both 1" and 2nd

spayn [35]

Answer: Foundries

Explanation: Casting is the method of making the liquid material to be shaped into solid form by being poured in a mold and having a hollow cavity . The liquid then turns into a solid state and this is known as casting. the casting odd metal is usually carried out in different shapes by the help of furnaces ,gases, molds etc.This process is usually performed in the certain industries known as foundry.

4 0

3 years ago