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