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2 years ago

List 3 types of heat exchangers, and classify them?

Engineering

1 answer:

frez [133]2 years ago

3 0

Answer:

Concentric tubes or double tube.

Casing and tubes.

Plates.

Explanation:

There are two classify of heat exchange:

1) Direct contact heat exchanger: the exchange heat is produced by the mixture betweenn two fluids, for example refrigeration towers.

2) Indirect contact heat exchange: the fluids never mix, and exchange the heat across a surface.

For example:

Concentric tubes or double tube: the fluid travel trough the central tube, and in the extern tube (bigger diameter) have other fluir with a different tempreature which can give o became the heat of the central fluid.

Casing and tubes are used in Industries, which have a lot of tube inside tha casing.

Plates: the fluid travel throug the metal plates.

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Water at atmospheric pressure boils on the surface of a large horizontal copper tube. The heat flux is 90% of the critical value

masya89 [10]

Answer:

The tube surface temperature immediately after installation is 120.4°C and after prolonged service is 110.8°C

Explanation:

The properties of water at 100°C and 1 atm are:

pL = 957.9 kg/m³

pV = 0.596 kg/m³

ΔHL = 2257 kJ/kg

CpL = 4.217 kJ/kg K

uL = 279x10⁻⁶Ns/m²

KL = 0.68 W/m K

σ = 58.9x10³N/m

When the water boils on the surface its heat flux is:

$q=0.149h_{fg} \rho _{v} (\frac{\sigma (\rho _{L}-\rho _{v})}{\rho _{v}^{2} } )^{1/4} =0.149*2257*0.596*(\frac{58.9x10^{-3}*(957.9-0.596) }{0.596^{2} } )^{1/4} =18703.42W/m^{2}$

For copper-water, the properties are:

Cfg = 0.0128

The heat flux is:

qn = 0.9 * 18703.42 = 16833.078 W/m²

$q_{n} =uK(\frac{g(\rho_{L}-\rho _{v}) }{\sigma })^{1/2} (\frac{c_{pL}*deltaT }{c_{fg}h_{fg}Pr } \\16833.078=279x10^{-6} *2257x10^{3} (\frac{9.8*(957.9-0.596)}{0.596} )^{1/2} *(\frac{4.127x10^{3}*delta-T }{0.0128*2257x10^{3}*1.76 } )^{3} \\delta-T=20.4$

The tube surface temperature immediately after installation is:

Tinst = 100 + 20.4 = 120.4°C

For rough surfaces, Cfg = 0.0068. Using the same equation:

ΔT = 10.8°C

The tube surface temperature after prolonged service is:

Tprolo = 100 + 10.8 = 110.8°C

8 0

2 years ago

An excavation is at risk for cave-in and water accumulation because of the excess soil that has accumulated. What type of excava

s344n2d4d5 [400]

Answer:

Among the different types of excavation protection system, as a way of preventing accidents against cave-ins, the sloping involves cutting back the trench wall at an angle inclined away from the excavation. Shoring requires installing aluminum hydraulic or other types of supports to prevent soil movement and cave-ins. Shielding protects workers by using trench boxes or other types of supports to prevent soil cave-ins (OSHA). In addition, the regulations do not allow employees to work on excavations where there is an accumulation of water. If this occurs, water on the site must be constantly removed by suitable equipment preventing water from accumulating. The entry of surface water into the excavations must also be prevented by means of diversion ditches, dam, or other suitable means.

Explanation:

3 0

2 years ago

Roads in rural areas are _______.

Roman55 [17]

Answer:

Explanation:

Mountain roads often zigzag across a mountain with a series of sharp turns called. switchbacks.

6 0

2 years ago

Read 2 more answers

When your fixing a car, what is the first thing you want to do?

Shtirlitz [24]

Answer:

Changing oil.

Explanation:

You need to regularly check and change your car’s oil to ensure smooth running of the vehicle and to prolong the lifespan of its engine.

6 0

2 years ago

Tires can be recycled instead of thrown out.<br> True<br> False

Arisa [49]

Answer:

True :)

Explanation:

You can recycle it! Tire recycling is the most practical and environment-friendly way of disposing of old and worn-out tires. Due to their inherent durability, large volume and environment and health risks, tires are one of the most problematic sources of solid wastes.

Hope it helped have a nice day! :)

8 0

1 year ago