Asee 2014 zone i conference, april 35, 2014, university. This is fairly efficient at first but quickly runs out of steam pun intended. What is parallelflow and counterflow heat exchanger. In this method, a global heat exchanger is divided into several sub heat exchangers in seriesand parallel arrangement 14. The results are analyzed and summarized in terms of heat exchanger effectiveness, the ratio of the actual heat transfer rate to the maximum possible heat transfer rate. The area density for doublepipe heat exchanger can not be in the order of 700. The heat exchanger di three heat exchangers in series or parallel, or combinations incor mensions are 12. Unfortunately, the flow in most heat exchangers is so complicated that a simple solution to the differential equation is not possible and we are forced to take another approach. Calculate the required heat transfer rate, q, in btuhr from specified information about fluid flow rates and temperatures. The double pipe heat exchanger is one heat exchanger pipe inside another larger pipe for either counter flow or parallel flow pattern. Here, we will cite only those that are immediately useful for design in shell and tube heat exchangers with sensible heat transfer on the shellside. Pdf analysis of a parallelflow heat exchanger with a heat source. The model was simulated in comsol for an oil to water heat exchanger.
Optimal operation of parallel heat exchanger networks at ntnu. Pdf in this work, a modified analysis of a parallel flow plate heat exchanger that takes into account a volumetrically uniform heat source in the. This can sometimes require the heat transfer area to be divided between parallel heat exchangers separated with valves. The present work is directed towards the modeling of shell and tube parallel flow heat exchanger in solid works 2014 and setting.
The heat exchange duty a llows calculation of the log mean. The basic design equation and overall heat transfer coefficient the basic heat exchanger equations applicable to shell and tube exchangers were developed in chapter 1. In a parallel flow exchanger, the temperature difference between the hot and cold fluids keep on. They involve heat exchange between two fluids separated by a solid and encompass a wide range of flow configurations. Fluid engine oil sea water inlet temperature, c 65 20 outlet temperature, c 55 25 heat load, kw 117. The effect of fluid flow rate on the performance of parallel flow heat exchangers in an extended plate with regard to thermal efficiency,overall heat transfer coefficient, convective heat transfer coefficient, flow rate, and reynolds number. Laminar counterflow parallelplate heat exchangers archivo digital. The shell side heat transfer coefficient by this method is given by hshoc fn fw fb fl where, 0. It is referred to as a laminar flow heat exchanger if the surface area density is above about 3000 m2m 3 914 ft2ft3, and as a micro heat exchanger if the surface area density is above about 10,000 m2m 3 3050 ft2ft3. The flow in a heat exchanger can be arranged as parallel flow, counter flow, and cross flow. Make an initial estimate of the overall heat transfer coefficient, u, based on the fluids involved.
Fig 1 schematic layout of a heat exchanger network consisting of parallel branches. A counter flow or countercurrent shell and tube heat exchanger s construction is in many ways identical to that of a parallel flow shell and tube heat exchanger. The diagram shows the dimension of the heat exchanger in a cross section view figure 3 impact factor jcc. While as expected the fouled heat exchanger had a lower performance and therefore cooled the working fluid less, the performance of the counter heat exchanger unexpectedly of the parallel heat exchanger. Parallel flow heat exchanger in a parallel flow heat exchanger, the two fluid streams hot and cold flow through the heat exchanger in the same direction. Four different types of plate fins plain rectangular, offset strip, corrugated louvered and wavy fin are embodied within heat exchanger for both cocurrent and countercurrent flow arrangements have been selected for the study.
Whats the difference between parallel flow, counter flow. The heat exchange is performed between hot and cold water. Variation of the fluid temperatures in a parallel flow doublepipe heat exchanger. Heat is transferred from the warm fluid through the wall of the inner tube the socalled heating. It is the shell and tube heat exchanger temperature, considering normal operating conditions. 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. The schematic and the temperature profile of the fluid streams in parallel flow heat exchanger are. Under comparable conditions, more heat is transferred in a counterflow arrangement than in a parallel flow heat exchanger. Heat exchangers are typically classified according to flow arrangement and type of construction. To demonstrate the basic equations of heat exchanger operation. Ideally, if not in a required heat transfer course at least in an elective thermal systems course, one would also discuss the utube exchanger and at least one cross flow exchanger. Such an arrangement is shown schematically in figure 2a and b. To study the heat transfer phenomena in parallel counter flow arrangements.
Describe hot and cold fluid flow in parallel flow, counter flow, and cross flow heat exchangers. Heat is transferred from the warm fluid through the wall of the inner tube the socalled heating surface to the cold fluid. To calculate rate of heat transfer, lmtd and overall heat transfer coefficient for both type of heat exchanger. Modelling of a parallel and counter flow heat exchanger. Other articles where parallel flow heat exchanger is discussed. Asee 2014 zone i conference, april 35, 2014, university of. May 11, 2020 threefluid compact heat exchanger of platefin type with parallel flow configuration is optimised for the entropy generation. Modeling and design of plate heat exchanger intechopen. Heat transfer equation sheet heat conduction rate equations fouriers law. Design and development of parallel counter flow 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. The heat exchanger development did by many researchers using softwares, design methods, changing the designs, changing shape of tubes.
The simplest heat exchanger is one for which the hot and cold fluids move in the same or opposite directions. The circles indicate shell andtube heat exchangers. Parallel and counter flow designs heat exchangers engineers. Pdhonline course m371 2 pdh shell and tube heat exchangers. In parallel flow heat exchanger, the two fluids flow in same direction and parallel to each other. Analysis of a counter flow parallelplate heat exchanger. A liquid twophase fluid heat exchanger is referred to as a compact heat exchanger if the surface area density on any one fluid side is above about 400 m2m 3 122 ft2ft3. Fluid engine oil sea water inlet temperature, c 65 20 outlet temperature, c 55 25 heat. A representative repeating unit cell of the multichanneled heat exchanger was taken as the computational domain, which includes a cold channel and a hot channel separated by plates. Similar expressions may be obtained for a parallel flow heat exchanger. Optimal operation of parallel heat exchanger networks. The streams shown are connected to the tube side of the exchangers. To understand the basic operation of heat exchangers. In a parallel flow exchanger, both fluids in the heat exchanger flow in the same direction.
Make an initial estimate of the overall heat transfer coefficient, u, based on. Concentrictube heat exchangers parallel flow counterflow simplest configuration. Heat exchanger efficiency 4 has also been defined on the basis of efficiency of a fin of a constant area with its tip insulated, as a a f tanhf 3 where f a is the heat exchanger number and is expressed as, 2 ntu1 r f a for counter flow heat exchanger fand for parallel flow 2 ntu1 r a where ntu is the number of transfer units. In this paper, we analyze the flow of two constant property. The apparatus three identical, copper fintube, cross flow heat exchangers are can be set to test the performance of a solo heat exchanger, two or mounted on a board as shown in figure 1. Result of parallel flow heat exchanger type of shell inlet shell outlet total tal heat transfer configu iguration flow temperature temperature rate ate tube wall without ut baffles 300 k 376. If there is an additional resistance either in series or in parallel, then replace with in all the above lumped ca. A plate heat exchanger is a compact type of heat exchanger that uses a series of thin plates to transfer heat between two fluids. Effect of flow distribution in parallel heat exchanger networks. Sometimes determining sufficient excess heat transfer area or additional heat exchangers to take into account the effects of rapid fouling processes can make up a significant part of the whole heat exchanger design problem. Detailed design optimisation of threefluid parallelflow. Combining each of these resistances in series gives.
Although this configuration typically results in lower efficiencies than a. In a crossflow heat exchanger the direction of fluids are perpendicular to each other. Measurements are made of the heat transferred between two identical parallel plate heat exchangers under conditions of oscillating. In the cocurrent flow parallel flow heat exchanger the hot and cold fluids enter at the same end, flow in the same direction, and leave at the same end.
The main difference is that the tubeside fluid enters the exchanger at the opposite end of the shellside fluid. In parallel flow both the hot and cold streams enter the heat exchanger at the. The corrugations of the plates and the small hydraulic diameter enhance the formation of turbulent flow, so that high rates of heat transfer can be obtained for the fluids. The second heat transfer process is convection, or heat transfer due to a flowing fluid. Aim to determine the heat transfer coefficient of a tubular heat exchanger both experimentally and. New heat exchangers have been designed for emerging thermal. Effectiveness and efficiency analysis of parallel flow and. Cfd analysis and performance of parallel and counter flow in. The major types of heat exchanger include double pipe, shelltube, plate and shell, plate fin, and phase change heat exchangers. Parallel flow heat exchanger in this type of heat exchanger the hot and cold fluids flow in the same direction, hence the. Three basic types of heat exchanger the simple parallel or counter. Consequently, up to 90% of the heat can be recovered, compared to only 50% in the case of shellandtube heat exchangers.
Newtonian fluids through a multilayered counterflow parallel plate heat exchanger composed by a. Heat exchanger types heat exchangers are used to energy conversion and utilization. Design and performance study of shell and tube heat exchanger. Background a heat exchanger is a heat transfer device whose purpose is the transfer of energy from one moving fluid stream to another moving fluid stream. In another recent study of the optimization of the shell and tube heat exchanger, 2 proposed a method, motivated by constructed theory. Amjed ahmed example 1 in a counter flow heat exchanger, water is being chilled by a sodium chloride brine. Design and performance study of shell and tube heat. Pdf design and development of parallel counter flow heat.
Mar 12, 2018 counter flow shell and tube heat exchangers. The two fluid streams enter at one end of the heat exchanger and leave at the other end. Effectiveness and lmtd correction factor of the cross flow. Counter flow heat exchangers are the most efficient of the three types. Design a double pipe heat exchanger with bare inner multitubes that can be used to cool engine oil with cold sea water. Equation is used when simple counter or cocurrent flows exist. Same as with the design pressure, this value is defined by the thermal design. This heat exchanger consists of two concentric pipes of different diameters. The heat exchanger is a device which transferred the. In convection heat transfer, the heat is moved through bulk transfer of a nonuniform temperature fluid. In addition, the overall heat transfer equation for the exchanger must be solved simultaneously. In this new scenario, the plate heat exchanger can play an important role. Figure 9 represents the directions of fluid flow in the parallel and counterflow exchangers.
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. Review of experimental analysis of parallel and counter. Therefore, it can not be classified as a compact heat exchanger. The many types of heat exchangers can be characterized. Pdf a seriesparallel heat exchanger experiment karen. The dimensions and mass of the heat exchanger may be. 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. Cfd analysis and performance of parallel and counter flow.
John richard thome ltcm sgm epfl heat transfer heat exchanger design 1er mars 2008 4 41. Reason for heat exchangers a heat exchanger is a piece of equipment built for efficient heat transfer from one medium to. Heat exchangers 73 individual thermal resistances of the system. Twophase distribution of r4a in a header of a parallel.
To use the parallel flow heat exchanger as a refrigerant evaporator, it is very important to evenly distribute the twophase refrigerant especially the liquid into the. Pdf in this work, a modified analysis of a parallelflow plate heat exchanger that takes into account a volumetrically uniform heat source in the. Whats the difference between parallel flow, counter flow and. Heat transfer is negligible in radiation as compare to conduction and convection. Tubular heat exchanger, heat transfer coefficient, heat transfer area, heat transfer efficiency. Review of experimental analysis of parallel and counter flow. Although this configuration typically results in lower efficiencies than a counter flow. The temperature practices across the tube length are shown in the below figure. A heat exchanger can also be operated in counterflow, in which the two fluids flow in parallel but opposite directions. K at an initial temperature of 205c to heat water, flowing at 225kghr from 16c to 44c. In addition, for a heat exchanger network of two heat exchanger in series parallel to one heat exchanger, a comprehensive analysis is done for an extreme case where a decreasing hot stream temperature in one heat exchanger givesacoolinge.
In parallel flow, both the hot and cold fluids enter the heat exchanger at the. Some common examples are parallel low heat exchangers, in. Parallel flow heat exchanger in this type of heat exchanger the hot and cold fluids flow in the same direction, hence the name parallel flow. Heat exchanger is a device in which heat is transferred from one fluid to another. Double pipe heat exchanger can be divided into major classes depending on the direction of the flow of hot and cold streams on either side of the tube wall.
676 1561 808 27 691 165 1455 82 859 810 458 368 1681 1113 674 1538 23 920 1474 331 495 1555 344 1408 1653 1193 1206 658 123 1080 748 1852 143 68 442 1891 621 1629 821