New heat exchangers have been designed for emerging thermal engineering. Kj05 heat exchanger effectiveness 2874 6 comparison of effectiveness for counterflow, crossflow, multipass, and parallel flow heat exchangers for c 1. The main difference is that the tubeside fluid enters the exchanger at the opposite end of the shellside fluid. Comparison of heat exchanger types parallel heat exchanger.
Heat exchanger transfer thermal energy from one medium to another. The materialprocess decision on a parallel flow heat exchanger design. The exchanger takes one inlet and one outlet for hot fluid stream, and one inlet and one outlet for cold fluid stream. The flow in a rod baffle heat exchanger is parallel to the tubes, and flowinduced vibrations are virtually eliminated by the baffle. Introduction heat exchanger airwater, applied to the current paper, due to the flow of fluids in the same direction is called the heat exchanger with the parallel flow. Heat exchangers have widespread industrial and domestic applications. Optimizing the performance of the heat exchanger results in efficient utilization of energy with reduction in total volume and the. The heat exchanger must be isolated from system vibrations using flexible piping connections and isolation pads on the mounting feet. Comparison of heat exchanger types each of the three types of heat exchangers parallel, cross and counter flow has advantages and disadvantages. The oil provides an average convection coefficient ho 400 wm2k on the outside of the tubes.
A shellandtube heat exchanger must be designed to heat 2. Design and development of parallel counter flow heat exchanger. Heat transfer l32 p2 temperatures for parallel and. A counter flow or countercurrent shell and tube heat exchangers construction is in many ways identical to that of a parallel flow shell and tube heat exchanger.
Other articles where parallelflow heat exchanger is discussed. Whats the difference between parallel flow, counter flow and. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants. The simplest heat exchanger is one for which the hot and cold fluids move in the same or opposite directions. Schaefer september 12, 2005 brief derivation of the lmtd to design or predict the performance of a heat. The heating is to be accomplished by passing hot engine oil, which is at 160c, through the shell side of the exchanger.
Experimental analysis of performance of heat exchanger with. Plate heat exchanger, how it works working principle hvac industrial engineering phx heat transfer duration. Counter flow heat exchangers are the most efficient of the three types. Integrated cleaning of the heat transfer surfaces therefore is of great importance to continuously maintain the maximum heat transfer capacity. Alfa laval spiral heat exchangers 5 waste heat recovery the secret is the true countercurrent. Asee 2014 zone i conference, april 35, 2014, university of bridgeport, bridgeport, ct, usa. A representative repeating unit cell of the multichanneled heat. That means that given an infinitely long heat exchanger and 0 and 100 fluids, the eventual temperature of both the hot and the cold will reach 50. Whats the difference between parallel flow, counter flow. Note that in a counterflow heat exchanger the outlet temperature of the cold fluid can exceed the outlet temperature of the hot fluid but this cannot happen in a parallel flow system. The present work is directed towards the modeling of shell and tube parallel flow heat exchanger in solid. Temperature profiles in a counterflow and b parallel flow single pass heat exchangers. Asee 2014 zone i conference, april 35, 2014, university. Mar 12, 2018 counter flow shell and tube heat exchangers.
This includes knowledge of precautions regarding media type, pressures, temperatures in the heat exchanger as well as specific precautions required by the process. However, there are applications where parallel flow has its benefits, such as when. A heat exchanger can have several different flow patterns. Heat exchanger and its types engineering solutions. In shellandtube heat exchangers the flow enters different tubes in parallel. 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.
This study was done by changing the parallel flow configuration into counter flow configuration under laminar flow regime. Several huber heat exchanger rowin units can be installed in parallel or in. The heat exchanger design equation can be used to calculate the required heat transfer surface area for a variety of specified fluids, inlet and outlet temperatures and types and configurations of heat exchangers, including counterflow or parallel flow. If the heat exchanger is located at the inlet or discharge of a blower with a pulsating flow, such as a roots type rotary lobe blower, the heat exchanger must be protected from the pulsation by a chambered silencer. Difference in counter and parallel flow heat exchanger. A heat exchanger can also be operated in counterflow, in which the two fluids flow in parallel but opposite directions. Effectiveness and efficiency analysis of parallel flow and. The design of parallel flow heat exchanger is advantageous when two fluids are required to be brought to nearly the same temperature. T between the two fluids over the length of the heat exchanger is maximized, therefore the log mean temperature for a counter flow heat exchanger is larger than the log mean temperature for a similar parallel or cross flow heat exchanger. Pdf material selection and fluid flow analysis of parallel flow.
Asee 2014 zone i conference, april 35, 2014, university of. The heat exchanger block is used when two process streams are to exchange heat based on equations 11 14. Pdf design of a parallel tube heat exchanger muhammad. A heat exchanger is a component that allows the transfer of heat from one fluid liquid or gas to another fluid. Combining each of these resistances in series gives. But of the three, the counter flow heat exchanger design is the most efficient when comparing heat transfer rate per unit surface area. To reduce the temperature of a hot fluid by means of a cooler fluid 3. The fluid velocity, reynolds number, overall heat transfer coefficient, baffle spacing, number of baffles, pressure drop, lmtd, helix angle of tubes plays very. This paper developed a numerical model to simulate a counter flow parallel heat exchanger. Pdf design and development of parallel counter flow heat. This heat exchanger consists of two concentric pipes of different diameters. Dec 01, 2015 plate heat exchanger, how it works working principle hvac industrial engineering phx heat transfer duration.
Derive the expression for log mean temperature difference. Effectiveness of parallelplate heat exchangers in thermoacoustic devices ray scott wakeland and robert m. Assuming the outer surface of the heat exchanger to be well insulated so that any heat transfer occurs between the two fluids, and disregarding any changes in kinetic and potential energy, an energy balance on each fluid. R sekulib university of kentucky introduction a heat exchanger is a device that is used for transfer of thermal energy enthalpy between two or more fluids, between a solid surface and a fluid, or between solid particulates and a.
Heat exchanger, heat transfer, fins surfaces, single phase, plate fins, performance 1. T2 represent the temperature difference at each end of the heat exchanger, whether parallel flow or counterflow. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. New heat exchangers have been designed for emerging thermal. The heat exchanger shall be operated by persons who have studied the instructions in this manual and have knowledge of the process. The main difference is that the tubeside fluid enters the exchanger at. A counterflow heat exchanger is the most efficient flow pattern of the three. Heat exchanger effectiveness ntu method if more than one of the inlet and outlet temperature of the heat exchanger is unknown, lmtd may be obtained by trial and errors solution. Optimal operation of parallel heat exchanger networks. A seriesparallel heat exchanger experiment karen a.
Experimental analysis of performance of heat exchanger. 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. Three basic types of heat exchanger the simple parallel or counter. M elbalsohi, department of mechanical engineering university of bridgeport, bridgeport, ct, usa. In general, parallel flow heat exchangers considered less efficient than counter flow heat exchangers in terms of transferring heat from one fluid to another. Whether parallel or counterflow, heat transfer within the heat exchanger involves both conduction and convection. The flow in a heat exchanger can be arranged as parallel flow, counter flow, and cross flow. A heat exchanger is a system used to transfer heat between two or more fluids.
The basic component of a heat exchanger can be viewed as a tube with one fluid running through it and another fluid flowing by on the outside. Heat exchangers are used in both cooling and heating processes. Design and development of parallelcounter flow heat exchanger. Parallel and counter flow designs heat exchangers engineers. A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. Keoliana the pennsylvania state university, graduate program in acoustics and applied research laboratory, p. Pdf design and development of parallel counter flow. Reason for heat exchangers a heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another hot and cold fluid. Pdf analysis of a parallelflow heat exchanger with a heat source. When tubes start to foul, the local crosssection decrease local velocity increase deposits removal. More details on heat exchanger design and application can be found in literature 47. Heat exchangers are typically classified according to flow arrangement and type of construction.
Moreover heat exchangers of any type can be connected in series for certain purposes. Pdf a seriesparallel heat exchanger experiment karen flack. The figure below show heat exchanger schematics and the temperature profiles for both cocurrent and countercurrent desig. A value is needed for the overall heat transfer coefficient for the given heat exchanger. The notes are intended to describe the three types of heat transfer and provide. There are probably heat exchanger in your office building which heat transfer from hot water to the ventilation system in the winter and from the indoor air to the. Optimizing the performance of the heat exchanger results in efficient utilization of energy with reduction in total volume and the weight of the heat exchanger. Experimental study on parallel and counter flow configuration. Flack to more open ended problems and physical experiments. A heat exchanger is a heat transfer device that exchanges heat between two or more process fluids. Heat exchangers 73 individual thermal resistances of the system.
In this work, heat transfer coefficients of shell and helically coiled tube heat exchanger using al 2 o 3 water nanofluid were studied. Lets take the case when we want to extract the maximum amount of heat from a given hot stream. In parallel flow, both the hot and cold fluids enter the heat exchanger at the same end and move in the same direction, as shown in figure 1. Which conditions will you select, parallel flow or counter. Heat exchangers are devices that facilitate the exchange of heat between two fluids with high effectiveness and low investment and low maintenance cost. In convection heat transfer, the heat is moved through bulk transfer of a nonuniform temperature fluid. The second heat transfer process is convection, or heat transfer due to a flowing fluid. To heat a cooler fluid by means of a hotter fluid 2. Analysis of a counter flow parallelplate heat exchanger asee. It is common knowledge amongst heat exchanger designers that a counter flow heat exchanger installation is more efficient than the parallel flow alternative, but for everyone else it can be a bit of a mystery.
Introduction to engineering heat transfer these notes provide an introduction to engineering heat transfer. Analysis of a counter flow parallelplate heat exchanger ruoxu jia, junling hu, and abubaker e. Schaefer september 12, 2005 brief derivation of the lmtd to design or predict the performance of a heat exchanger, the lmtd and the e. One fluid hot convectively transfers heat to the tube wall where conduction takes place across the tube to the opposite wall.
The heat exchanger development did by many researchers using softwares, design methods, changing the designs, changing shape of tubes. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the hottest coldfluid. John richard thome ltcm sgm epfl heat transfer heat exchanger design 1er mars 2008 4 41. The term heat exchanger applies to all equipment used to transfer heat between two streams. Therefore, it can not be classified as a compact heat exchanger. Heat exchangers are used widely in many industries for heat recovery or cooling purposes. What is parallelflow and counterflow heat exchanger. However, the term is commonly used to equipment in which two process streams exchange heat with each other. Since the fluid flows continuously in one single channel the force of the fluid acts against. Htepisode11effectiveness method for parallel flow heat exchanger duration.
This is fairly efficient at first but quickly runs out of steam pun intended. The temperature differential is nowhere near as high as at the start of the parallel heat exchanger. Another approach introduce the definition of heat exchanger effectiveness, which is a dimensionless with ranging between 0 to1. The major types of heat exchanger include double pipe, shelltube, plate and shell, plate fin, and phase change heat exchangers. Heat transfer processes set limits to the performance of aerospace components and systems and the subject is one of an enormous range of application. Chapter 52 heat exchangers, vaporizers, condensers joseph w. Heat is transferred from the warm fluid through the wall of the inner tube the socalled heating surface to the cold fluid. Why counter flow heat exchangers are more efficient. Difference in counter heat exchanger and parallel flow heat. It is active to some degree or another in everything.
Future scope the concept of entropy generation analysis can also be applied in the above analysis. Effectiveness of parallelplate heat exchangers in thermoacoustic devices. Parallel and counter flow heat exchanger lab experiment. The heat is then convectively transferred to the second fluid. Parallel and counter flow designs heat exchangers although ordinary heat exchangers may be extremely different in design and construction and may be of the single or twophase type, their modes of operation and effectiveness are largely determined by the direction of the fluid flow within the exchanger. Heat exchanger theory and the heat exchanger design equation. There are probably heat exchanger in your office building which heat transfer from hot water to the ventilation.
Effectiveness of parallel plate heat exchangers in thermoacoustic devices ray scott wakeland and robert m. Pdf in this work, a modified analysis of a parallelflow plate heat exchanger that takes into account a volumetrically uniform heat source in the hot. Aug 28, 2017 you can see that using linear flow, the most you can ever heat or cool to is the midpoint of the differential. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the hottest coldfluid temperature greater than the coldest hotfluid temperatue. Heat exchanger effectiveness 2774 5b common equations for effectiveness and ntu table. Parallel and counter flow designs heat exchangers although ordinary heat exchangers may be extremely different in design and construction and may be of the single or twophase type, their modes of operation and effectiveness are largely determined. Derive the expression for log mean temperature difference lmtd in parallel flow heat exchanger. Heat exchangers have wide applications in modern industries. Consider a parallelflow heat exchanger, which is used to cool oil from 70c to 40c using water available at 30c.
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