Example 3: Taking the shell and tube heat exchanger described in Example 1, how many tubes of 3 inch diameter and 10 ft length should be used? Solution: The surface area per tube will be:
Sa = πDL = π (3/12)
(10) ft2 = 7.854 ft2 – (D – tube diameter in ft).
How do I choose a heat exchanger?
A starting point for heat transfer solution sizing and selection is to compare models that fit the temperatures and pressures required for the process. The best type of heat exchanger depends on
design parameters, fluid characteristics, space, and budget
.
Why shell and tube heat exchanger is widely used?
Shell and tube Heat Exchangers have
the ability to transfer large amounts of heat in relatively low cost, servicable designs
. They can provide large amounts of effective tube surface while minimizing the requirements of floor space, liquid volume and weight.
What is the most efficient arrangement of shell and tube heat exchanger?
Counter current heat exchangers
are most efficient because they allow the highest log mean temperature difference between the hot and cold streams. Many companies however do not use two pass heat exchangers with a u-tube because they can break easily in addition to being more expensive to build.
How do you size a heat exchanger plate?
Many customers ask, “how do you know what size plate exchanger to install in your domestic hot water tank?” A simple rule of thumb is
2 to 3 people in one house will determine
a 10 plate. A 10 plate heat exchange is enough for 2 and 3 people.
How many tubes are in a tube and shell heat exchanger?
waste heat boiler in power plant gas turbine are shell & tube type heat exchanger are also larger size and having
5000-12000 number of tubes
.
Which type of heat exchanger is most efficient?
Plate exchanger
is the most efficient due to turbulent flow on both sides. High heat-transfer coefficient and high turbulence due to even flow distribution are important. However, a plate heat exchanger regenerator is restricted to low viscosities.
What are the different types of heat exchangers?
- 2.1 Shell and tube heat exchanger.
- 2.2 Plate heat exchangers.
- 2.3 Plate and shell heat exchanger.
- 2.4 Adiabatic wheel heat exchanger.
- 2.5 Plate fin heat exchanger.
- 2.6 Finned tube heat exchanger.
- 2.7 Pillow plate heat exchanger.
- 2.8 Waste heat recovery units.
How do you calculate tube pitch in heat exchanger?
TEMA standards recommends a minimum tube pitch of
1.25 * Tube outer diameter for triangular pitch
. For example, if we have a tube outer diameter of 12.7 mm (0.5 inch) then the recommended tube pitch for triangular pitch arrangement is: 1.25 * 12.7 mm = 16 mm (0.6 inch).
Where would you use shell and tube double pipe heat exchangers?
When to use double pipe heat exchanger and shell and tube heat exchanger? Double pipe heat exchangers are used
when the heat transfer area is small say up to 14 m2.
If we connect them in series to increase the heat transfer area it will require much space as well the pressure drop will be higher due to more fittings.
Where are shell and tube heat exchangers used?
Shell-and-tube heat exchangers are used in
the chemical, food, oil and gas and other fields
. They are used as evaporators and condensers.
Why shell and tube is better than double pipe?
One pipe is for hot fluid and another is for cold fluid. … Also in case of shell & tube(S&T)
the hot fluid will have more turbulence than in double pipe heat exchanger
(HE) since there are no of tubes within a shell the area for convective heat transfer is considerably increased. so these are much more preferred.
What are the different types of shell and tube heat exchanger?
The three flow types of shell and tube heat exchangers are
parallel, counter, and cross
. The design, operation, and applications necessitate the three flow types be used in combinations. Parallel flow is when the shell and tube sides enter the heat exchanger at the same end and flow directly to the opposite end.
How efficient are shell and tube heat exchangers?
| Overall Heat Transfer Coefficient – U – | Shell and Tube 150-1200 25-200 | Plate and Frame 1000-4000 150-700 |
|---|
How does a shell and tube heat exchanger works?
A shell and tube exchanger consists of a number of tubes mounted inside a cylindrical shell. …
Two fluids can exchange heat, one fluid flows over the outside of the tubes while
the second fluid flows through the tubes. The fluids can be single or two phase and can flow in a parallel or a cross/counter flow arrangement.
What brazed PHE?
Material The brazed plate heat exchanger (BHE) consists of
thin corrugated stainless steel plates vacuum brazed together using copper
as the brazing material. Design Brazing the stainless steel plates together eliminates the need for sealing gaskets and thick frame plates.
How efficient is a plate heat exchanger?
With those factors embedded into industry calculations, plate heat exchangers are still consistently found to be the most efficient of all heat exchangers. Typically, they can achieve
efficiency rates of approximately 90%
.
How many pipes are in a heat exchanger?
Heat Exchangers
It consists of
two concentrically arranged pipes
or tubes, with one fluid flowing in the inner pipe and the other in the annulus between the pipes.
What is pitch in shell and tube heat exchanger?
The distance between the centers of the tube hole is called the tube pitch; normally the tube pitch is
1.25 times the outside diameter of the tubes
. Other tube pitches are frequently used to reduce the shell side pressure drop and to control the velocity of the shell side fluid as it flows across the tube bundle.
How do you know how many passes in heat exchanger?
The number of passes in a heat exchanger is generally determined by the
total flow of tube side fluid
, the exchanger area requirement, allowable pressure drop and any limitations in tube length (location, access, bundle pulling requirements, etc).
How is a plate type he better than a shell-and-tube he one of the following is not correct?
7. How is a Plate-type HE better than a Shell and tube HE, one of the following is not correct. Explanation: All the statements
are correct except that the thermal stress in higher in Plate type
, which in reality is higher in shell and tube owing to its lesser surface area compared to plat type HE.
What are the 3 types of heat exchangers?
- Shell and tube heat exchangers.
- Double pipe heat exchangers.
- Plate heat exchangers.
- Condensers, evaporators, and boilers.
What is the ideal flow type in a heat exchanger?
“
The counter flow pattern in shell and tube heat exchangers
is the most efficient.” The counter flow pattern is the most common in shell and tube heat exchangers, primarily because it's the most efficient. This flow pattern allows for the greatest temperature change between fluids.
What is a tube in tube heat exchanger?
5.11.
A shell-and-tube heat exchanger is the most common type of heat exchanger. It consists of a number of tubes (often finned)
placed inside a volume
(shell). One of the fluids runs through the tubes while the second fluid runs across and along the tubes to be heated.
What is the best material for a heat exchanger?
Generally, the two most commonly selected materials for heat exchangers are
aluminium and copper
. Both metals have the optimum thermal properties and corrosion resistance to make them ideal choices, with most of the differences being application-specific.
What are the four 4 contact type of heat exchanges?
- Double Tube Heat Exchangers: Double tube heat exchangers use what is known as a tube within a tube structure. …
- Shell and Tube Heat Exchangers: …
- Tube in Tube Heat Exchangers: …
- Plate Heat Exchangers:
How do you calculate the overall heat transfer coefficient for shell and tube heat exchanger?
The convective heat transfer coefficient of the shell and tube heat exchanger is calculated based on the following correlation:
(4) U = Q A × L M T D
where, A is total heat transfer area, m
2
, Q is heat transfer from hot stream into cold stream, W, LMTD is logarithmic mean temperature difference, K.
Which flow option would you choose for a double pipe heat exchanger Why?
If using two different fluids, the more vicious of the two will work best in
the shellside flow
, as it has more space in which to flow. If utilizing steam, consider piping it through the tubeside flow, as it will flow better in a smaller volume.
What can we infer from the name 2/4 shell and tube heat exchanger?
Explanation: In the given plot,
we can observe the temperature has three elbows, that means it takes three turns(4 tubes) while its temperature increases in the tube side while its shell side observes only one turn(2 sections)
. Hence we can easily infer from this that it is a 2-4 shell and tube HE.
What is the minimum baffle spacing for a shell and tube heat exchanger?
Minimum baffle spacing according to firmly established rules is equal to 20% of the shell diameter D
s
,
but not less than approximately 50 mm
.
What is the maximum baffle spacing for a shell and tube heat exchanger?
Sinnott (1993) concluded that effective baffle spacing range is
between 0.2 to 1 from shell diameter
[10].
What are the disadvantages of double pipe heat exchanger?
Disadvantages of Double Pipe Heat Exchangers
It does not mean that they cannot be used in parallel flow. They
have limitations in heat transfer rather than complicated designs
and should be used in low heat duties. Leaking is more often in this type (paired with more units)
What is shell and tube evaporator?
The main function of Shell & Tube Type Evaporator is to
act as a heat exchanger in a vessel form
. This is mainly done to cool closed circuit for re-circulating fluid flow. … The refrigerants passed through the expansion device that passed into tubes and evaporates to produce a cooling effect.
What are baffles in heat exchanger?
Baffles are
flow-directing or obstructing vanes or panels used to direct a flow of liquid or gas
. … Baffles are an integral part of the shell and tube heat exchanger design. A baffle is designed to support tube bundles and direct the flow of fluids for maximum efficiency.
How does a shell and tube condenser work?
A shell and tube exchanger consists of a number of tubes mounted inside a cylindrical shell. …
Two fluids can exchange heat
, one fluid flows over the outside of the tubes while the second fluid flows through the tubes. The fluids can be single or two phase and can flow in a parallel or a cross/counter flow arrangement.
What are baffle spacers and tie rods?
Tie rods and spacers are
used to hold the tube bundle together and to locate the shell baffles in the correct position
. Tie rods are circular metal rods screwed into the stationary tubesheet and secured at the farthest baffle by lock nuts. The number of tie rods depends on shell diameter and is specified, by TEMA.
What is parallel and counter flow heat exchanger?
A counter-flow heat exchanger is one in which the direction of the flow of one of the working fluids is opposite to the direction to the flow of the other fluid. In a parallel flow exchanger,
both fluids in the heat exchanger flow in the same direction
.
