Heat exchanger pdf file

Original Title: Heat Exchanger. Related titles. Carousel Previous Carousel Next. Jump to Page. Search inside document. Documents Similar To Heat Exchanger. Mohammed Kabiruddin. Kashish Mehta. Prateek Mall. Nur Amanina. Munir Baig. Baher Elsheikh.

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Briefing No. Harilaos Vasiliadis. Cristine Quizano. Satyam Sen. Pritpal Singh. Ritesh Soorkia. Abdelrehim Siraj. Samnang Hang. The foregoing warranties are void if the heat exchanger has been damaged, misused, subjected to abnormal use or service, or if payment for the heat exchanger is in default.

Misuse and abnormal use or service includes, but is not limited to, misapplication, improper installation or operation at abnormal temperatures. Keep the compressor operating until suction pressure is below 20 PSI. Close vent opening. Close drain opening and resume normal operation. S-2 2-D another 3-D. S-3 2-D another 3-D.

S-4 2-D another 3-D. S5 2-D another 3-D. S-6 2-D another 3-D. S-2R 2-D another 3-D. A short summary of this paper. Sachchidanand J. Sachin K. Starts with the introduction of heat exchangers and is concerned with the detailed classification of heat exchangers according to contact types, surface compactness, number of fluids, flow arrangement and construction features including their applications.

The study of shell and tube heat exchanger along with the comprehensive description of all the components of shell and tube heat exchanger. The factors affecting the performance of shell and tube heat exchanger is studied and its detailed discussion is given. Some research papers are studied in details and then review from those papers and the conclusions are described in this paper.

Keywords: Shell, tube, nozzle, channel, baffle. Typically one medium is cooled while the other is heated. In most heat exchangers, the fluids are separated by a heat transfer surface and ideally they do not mix. They are widely used in petroleum refineries, chemical plants, petrochemical plants, natural gas processing, air conditioning, refrigeration and automotive applications.

A heat exchanger is a device that is used to transfer thermal energy enthalpy between two or more fluids, between a solid surface and a fluid, or between solid particulates and a fluid, at different temperatures and in thermal contact.

In heat exchangers, there are usually no external heat and work interactions. Typical applications involve heating or cooling of a fluid stream of concern and evaporation or condensation of single- or Multi component fluid streams. In other applications, the objective may be to recover or reject heat, or sterilize, pasteurize, fractionate, distill, concentrate, crystallize, or control a process fluid. In a few heat exchangers, the fluids exchanging heat are in direct contact.

In most heat exchangers, heat transfer between fluids takes place through a separating wall or into and out of a wall in a transient manner. In many heat exchangers, the fluids are separated by a heat transfer surface, and ideally they do not mix or leak.

Such exchangers are referred to as direct transfer type, or simply recuperators. In contrast, exchangers in which there is intermittent heat exchange between the hot and cold fluids—via thermal energy storage and release through the exchanger surface or matrix— are referred to as indirect transfer type, or simply regenerators.

Common examples of heat exchangers are shell-and tube exchangers, automobile radiators, condensers, evaporators, air preheaters, and cooling towers. If no phase change occurs in any of the fluids in the exchanger, it is sometimes referred to as a sensible heat exchanger. There could be internal thermal energy sources in the exchangers, such as in electric heaters and nuclear fuel elements. Combustion and chemical reaction may take place within the exchanger, such as in boilers, fired heaters, and fluidized-bed exchangers.

Mechanical devices may be used in some exchangers such as in scraped surface exchangers, agitated vessels, and stirred tank reactors. Heat transfer in the separating wall of a recuperator generally takes place by conduction.

However, in a heat pipe heat exchanger, the heat pipe not only acts as a separating wall, but also facilitates the transfer of heat by condensation, evaporation, and conduction of the working fluid inside the heat pipe. In general, if the fluids are immiscible, the separating wall may be eliminated, and the interface between the fluids replaces a heat transfer surface, as in a direct-contact heat exchanger.

A heat exchanger consists of heat transfer elements such as a core or matrix containing the heat transfer surface, and fluid distribution elements such as headers, manifolds, tanks, inlet and outlet nozzles or pipes, or seals.

Usually, there are no moving parts in a heat exchanger; however, there are exceptions, such as a rotary regenerative exchanger in which the matrix is mechanically driven to rotate at some design speed or a scraped surface heat exchanger.

Thus, ideally, there is no direct contact between thermally interacting fluids. This type of heat exchanger also referred to as a surface heat exchanger.

Common applications of a direct-contact exchanger involve mass transfer in addition to heat transfer, such as in evaporative cooling and rectification; applications involving only sensible heat transfer are rare. Compared to indirect contact recuperators and regenerators, in direct-contact heat exchangers, very high heat transfer rates are achievable, the exchanger construction is relatively inexpensive, and the fouling problem is generally nonexistent, due to the absence of a heat transfer surface wall between the two fluids.

Surface Compactness: Compared to shell-and-tube exchangers, compact heat exchangers are characterized by a large heat transfer surface area per unit volume of the exchanger, resulting in reduced space, weight, support structure and footprint, energy requirements and cost, as well as improved process design and plant layout and processing conditions, together with low fluid inventory.

Number of fluids: Most processes of heating, cooling, heat recovery, and heat rejection involve transfer of heat between two fluids. Hence, two-fluid heat exchangers are the most common. Three fluid heat exchangers are widely used in cryogenics and some chemical processes e. Heat exchangers with as many as 12 fluid streams have been used in some chemical process applications. Flow arrangement: The choice of a particular flow arrangement is dependent on the required exchanger effectiveness, available pressure drops, minimum and maximum velocities allowed, fluid flow paths, packaging envelope, allowable thermal stresses, temperature levels, piping and plumbing considerations, and other design criteria.

Basically there are two types of heat exchangers as Single passing and multi passing. In single passing there are four different subtypes as parallel flow, counter flow, cross flow and split flow.

In multi passing there are three different subtypes as cross flow, Shell and tube heat exchanger and plate heat exchanger.

Construction features: Heat exchangers are frequently characterized by construction features. Four major construction types are tubular, plate-type, extended surface, and regenerative exchangers. Heat exchangers with other constructions are also available, such as scraped surface exchanger, tank heater, cooler cartridge exchanger etc.

Tubular exchangers can be designed for high pressures relative to the environment and high-pressure differences between the fluids. Tubular exchangers are used primarily for liquid-to-liquid and liquid-to-phase change condensing or evaporating heat transfer applications.

The plates are either smooth or have some form of corrugation, and they are either flat or wound in an exchanger. Generally, these exchangers cannot accommodate very high pressures, temperatures, or pressure and temperature differences. Plate heat exchangers PHEs can be classified as gasketed, welded one or both fluid passages , or brazed, depending on the leak tightness required.

Addition of fins can increase the surface area by 5 to 12 times the primary surface area in general, depending on the design. The resulting exchanger is referred to as an extended surface exchanger.

The heat transfer coefficient on extended surfaces may be higher or lower than that on unfinned surfaces. Generally, increasing the fin density reduces the heat transfer coefficient associated with fins. The heat transfer surface or elements are usually referred to as a matrix in the regenerator. To have continuous operation, either the matrix must be moved periodically into and out of the fixed streams of gases, as in a rotary regenerator or the gas flows must be diverted through valves to and from the fixed matrices as in a fixed matrix regenerator.

The latter is also sometimes referred to as a periodic-flow regenerator, a swing regenerator, or a reversible heat accumulator. Usually, it is cylindrical in shape with a circular cross section, although shells of different shapes are used in specific applications and in nuclear heat exchangers to conform to the tube bundle shape.

The shell is made from a circular pipe if the shell diameter is less than about 0. The E shell is the most common, due to its low cost and simplicity, and has the highest log-mean temperature-difference correction factor F. Although the tubes may have single or multiple passes, there is one pass on the shell side. To increase the mean temperature difference and hence exchanger effectiveness, a pure counter flow arrangement is desirable for a two-tube-pass exchanger.

This is achieved by use of an F shell having a longitudinal baffle and resulting in two shell passes. Split- and divided-flow shells, such as G, H, and J , are used for specific applications, such as thermosiphon boiler, condenser, and shell-side low pressure drops.

The K shell is a kettle reboiler used for pool boiling applications. Fig:3 Standard shell types From TEMA, Nozzles: The entrance and exit ports for the shell and tube fluids, referred to as nozzles, are pipes of constant cross section welded to the shell and channels.

They are used to distribute or collect the fluid uniformly on the shell and tube sides. Note that they differ from the nozzle used as a fluid metering device or in jet engines, which has a variable flow area along the flow length. Most common are the tube bundles with straight and U-tubes used in process and power industry exchangers.

However, sine-wave bend, J-shape, L-shape or hockey sticks, and inverted hockey sticks are used in advanced nuclear exchangers to accommodate large thermal expansion of the tubes. In most applications, tubes have single walls, but when working with radioactive reactive, or toxic fluids and potable water, double-wall tubing is used. In most applications, tubes are bare, but when gas or low- heat-transfer coefficient liquid is used on the shell side, low-height fins low fins are used on the shell side.

Also, special high-fluxboiling surfaces employ modified low-fin tubing. These are usually integral fins made from a thick- walled tube, Tubes are drawn, extruded, or welded, and they are made from metals, plastics, and ceramics, depending on the applications. Front and Rear-End Heads: These are used for entrance and exit of the tube fluid; in many rear-end heads, a provision has been made to take care of tube thermal expansion.

The front-end head is stationary, while the rear-end head could be either stationary allowing for no tube thermal expansion or floating, depending on the thermal stresses between the tubes and shell. The major criteria for selection of the front-end head are cost, maintenance and inspection, hazard due to mixing of shell and tube fluids, and leakage to ambient and operating pressures.

The major criteria for selection of the rear-end head are the allowance for thermal stresses, a provision to remove the tube bundle for cleaning the shell side, prevention of mixing of tube and shell fluids, and sealing any leakage path for the shell fluid to ambient. The purpose of longitudinal baffles is to control the overall flow direction of the shell fluid such that a desired overall flow arrangement of the two fluid streams is achieved.

For example, F, G, and H shells have longitudinal baffles. Transverse baffles may be classified as plate baffles and grid rod, strip, and other axial-flow baffles. Plate baffles are used to support the tubes during assembly and operation and to direct the fluid in the tube bundle approximately at right angles to the tubes to achieve higher heat transfer coefficients.

Plate baffles increase the turbulence of the shell fluid and minimize tube-to-tube temperature differences and thermal stresses due to the cross flow. The choice of baffle type, spacing, and cut is determined largely by flow rate, desired heat transfer rate, allowable pressure drop, tube support, and flow-induced vibrations.

These baffles for nuclear exchangers have small perforations between tube holes to allow a combination of cross flow and longitudinal flow for lower shell-side pressure drop. The combined flow results in a slightly higher heat transfer coefficient than that for pure longitudinal flow and minimizes tube-to-tube temperature differences.