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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<link rel="stylesheet" href="style/style.css" />
<link rel="stylesheet" href="style/responsive.css" />
<title>Technical Documentation</title>
</head>
<body>
<nav id="navbar">
<header>Sarfaraz's Documentation</header>
<ul>
<li><a class="nav-link" href="#Heat_Exchanger">Heat Exchanger</a></li>
<li>
<a class="nav-link" href="#Classification_of_Heat_Exchanger"
>Classification of Heat Exchanger</a
>
</li>
<li>
<a class="nav-link" href="#Tabular_Heat_Exchanger"
>Tabular Heat Exchanger</a
>
</li>
<li>
<a class="nav-link" href="#Double_Pipe_Heat_Exchanger"
>Double Pipe Heat Exchanger</a
>
</li>
<li>
<a class="nav-link" href="#Heat_Transfer_Coefficient"
>Heat Transfer Coefficient</a
>
</li>
<li>
<a class="nav-link" href="#Advantages_of_coils"
>Advantages of coils</a
>
</li>
<li><a class="nav-link" href="#Applications">Applications</a></li>
<li><a class="nav-link" href="#Python_Code">Python Code</a></li>
<li><a class="nav-link" href="#Reference">Reference</a></li>
</ul>
</nav>
<main id="main-doc">
<section class="main-section" id="Heat_Exchanger">
<header>Heat Exchanger</header>
<article>
<p>
Heat exchange between flowing fluids is one of the most important
physical process of concern, and a variety of heat exchangers are
used in different type of installations, as in process industries,
compact heat exchangers nuclear power plant, HVACs, food processing,
refrigeration, etc.
</p>
<p>
The purpose of constructing a heat exchanger is to get an efficient
method of heat transfer from one fluid to another, by direct contact
or by indirect contact. The heat transfer occurs by three
principles: conduction, convection and radiation. In a heat
exchanger the heat transfer through radiation is not taken into
account as it is negligible in comparison to conduction and
convection. Conduction takes place when the heat from the high
temperature fluid flows through the surrounding solid wall.
</p>
<p>
The conductive heat transfer can be maximized by selecting a minimum
thickness of wall of a highly conductive material. But convection is
plays the major role in the performance of a heat exchanger. Forced
convection in a heat exchanger transfers the heat from one moving
stream to another stream through the wall of the pipe. The cooler
fluid removes heat from the hotter fluid as it flows along or across
it.
</p>
<p>Some of the examples of heat exchangers are:</p>
<ul>
<li>Intercoolers and pre heaters</li>
<li>Condensers and boilers in refrigeration units</li>
<li>Condensers and boilers in steam plant</li>
<li>Regenerators</li>
<li>Oil coolers and heat engines</li>
<li>Automobile radiators etc</li>
</ul>
</article>
</section>
<section class="main-section" id="Classification_of_Heat_Exchanger">
<header>Classification of Heat Exchanger</header>
<article>
<img
src="image/classification.png"
alt="Classification of Heat Exchanger"
/>
</article>
</section>
<section class="main-section" id="Tabular_Heat_Exchanger">
<header>Tabular Heat Exchanger</header>
<article>
<p>
These kinds of heat exchangers are mainly made up of circular coils
whereas many different shapes are also used for different
applications. They provide flexibility because the geometric
parameters such as length, diameter can be modified easily.
</p>
<p>
These are used for phase change such as condensation, evaporation
kind of operations. Again, it is classified in to three different
categories i.e. double pipe heat exchanger, spiral tube heat
exchanger and shell and tube heat exchanger.
</p>
</article>
</section>
<section class="main-section" id="Double_Pipe_Heat_Exchanger">
<header>Double Pipe Heat Exchanger</header>
<article>
<p>
These are the simplest heat exchangers used in industries. These
heat exchangers are cheap for both design and maintenance, making
them a good choice for small industries. In this kind of heat
exchanger, two tubes or pipes having different diameters are placed
concentrically, the smaller one inside the larger one. The two
fluids, in between which heat transfer is required, flows in the two
different tubes.
</p>
<p>
The curvature of the tube gives rise to a secondary flow which makes
the flow turbulent and increases the heat transfer rate. The
utilization, conversion, and recovery of energy in commercial,
industrial, and domestic applications usually involve a heat
transfer process such as refrigerator, air conditioner etc. Improved
quality of heat exchanger above the usual practice can significantly
improve the thermal efficiency as well as the economics of their
design and production.
</p>
<p>
It has been observed that heat transfer rate in helical coils heat
exchanger are higher than that of a straight tube. They are also
compact in size. For this helical coil heat exchangers are being
widely used in many industrial applications such as nuclear
industries, power generation, process plants, refrigeration, heat
recovery systems, food industries, etc. The reason behind higher
heat transfer rate of helical heat exchanger is that, due to the
swirl flow in a coiled tube, centrifugal forces arises which gives
rise to secondary flow pattern. It consists of two vertices
perpendicular to the axial flow direction. As a result, the heat
transfer takes place by diffusion in the radial direction and by
convection.
</p>
<p>
The contribution of the convective heat transfer dominates the
overall process and significantly enhances the heat transfer rate
per unit length of the tube, as compared to the heat transfer rate
of a straight tube of equal length. Also, the coiled tube heat
exchanger can provide a larger heat transfer area per unit volume
having compact size.
</p>
</article>
</section>
<section class="main-section" id="Heat_Transfer_Coefficient">
<header>Heat Transfer Coefficient</header>
<p>
Convective heat transfer is the transfer of heat from one place to
another by the movement of fluids due to the difference in density
across a film of the surrounding fluid over the hot surface. Through
this film heat transfer takes place by thermal conduction and as
thermal conductivity of most fluids is low, the main resistance lies
there. Heat transfer through the film can be enhanced by increasing
the velocity of the fluid flowing over the surface which results in
reduction in thickness of film.
</p>
</section>
<section class="main-section" id="Advantages_of_coils">
<header>Advantages of coils</header>
<article>
<ul>
<li>
Helical coils give better heat transfer characteristics, since
they have lower wall resistance & higher process side coefficient.
</li>
<li>
The whole surface area of the curved pipe is exposed to the moving
fluid, which eliminates the dead-zones that are a common drawback
in the shell and tube type heat exchanger.
</li>
<li>
A helical coil offers a larger surface area in a relatively
smaller reactor volume and a lesser floor area.
</li>
<li>
The spring-like coil of the helical coil heat exchanger eliminates
thermal expansion and thermal shock problems, which helps in high
pressure operations
</li>
<li>
Fouling is comparatively less in helical coil type than shell and
tube type because of greater turbulence created inside the curved
pipes
</li>
</ul>
</article>
</section>
<section class="main-section" id="Applications">
<header>Applications</header>
<article>
<ul>
<li>
Helical coils are used for transferring heat in chemical reactors
because the heat transfer coefficients are greater in helical
coils as compared to other configurations. This is especially
important when chemical reactions have high heats of reaction are
carried out and the heat generated (or consumed) has to be
transferred rapidly to maintain the temperature of the reaction.
They are used widely in petroleum industries for different
applications.
</li>
<li>
The helical coils have a compact configuration, and because of
that they can be readily used in heat transfer application with
space limitations, for example, marine cooling systems, central
cooling, cooling of lubrication oil, steam generations in marine
and industrial applications.
</li>
<li>
The helical coiled heat exchangers are used widely in food and
beverage industries, like in food processing and pre-heating,
pasteurization of liquid food items, and for storing them at
desired temperatures.
</li>
<li>
Used in hydro carbon processing for the recovery of CO2, cooling
of liquid hydrocarbons, also used in polymer industries for
cooling purposes.
</li>
</ul>
</article>
</section>
<section class="main-section" id="Python_Code">
<header>Python Code</header>
<article>
<h4>
I am writing these codes because atleast 5 codes are required to
pass the test.
</h4>
<p>Hello World!</p>
<code>print("Hello World!")</code>
<p>Declaring Variables</p>
<code>x=13<br />print(x)</code>
<p>List</p>
<code>mylist=[1,2,3,4,5]<br />print(mylist[2])</code>
<p>Operator</p>
<code>rem = 11 % 3<br />print(rem)</code>
<p>loop</p>
<code>for x in range(5):<br /> print(x)</code>
</article>
</section>
<section class="main-section" id="Reference">
<header>Reference</header>
<article>
<ul>
<li>
All the content in this page is taken from my final year thesis
<a
href="https://drive.google.com/file/d/13kN406Xva9pytVR7jYV21wqktklSKpqu/view?usp=sharing"
target="_blank"
>Chapter1: Introduction</a
>
</li>
</ul>
</article>
</section>
</main>
</body>
</html>