Pdf design and development of parallel counter flow heat. The answer to this is rooted in experiment, but it can be motivated by considering heat flow along a bar between two heat reservoirs at t a, t b as shown in figure 2. For these designs a correction factor f is applied, using. Development of numerical simulation method for evaluation. Chapter 5 heat exchangers faculty of engineering and. Three basic types of heat exchanger the simple parallel or counter. In a parallel flow heat exchanger, the two fluid streams hot and cold flow through the heat exchanger in the. It is shown that for parallel flow, counter flow, and shell and tube heat exchanger the efficiency is only a function of a single nondimensional parameter called fin analogy number.
Heat exchanger analysis 3 the lmtd method for a singlepass counterflow heat exchanger the design value ua follows from ua q. Heat transferheat exchangers wikibooks, open books for an. 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 is transferred from the warm fluid through the wall of the inner tube the socalled heating surface to the cold fluid.
Heat transfer rate found more nearly by 30% in counter flow compared to parallel flow. Therefore, it can not be classified as a compact heat exchanger. Calculation of heat exchanger consider a parallelflow heat exchanger, which is used to cool oil from 70c to 40c using water available at 30c. It may be written for a parallel flow or counterflow. Equation is used when simple counter or cocurrent flows exist. Two types of flow arrangement are possible in a doublepipe heat exchanger. The fluid velocity, reynolds number, overall heat transfer coefficient, baffle spacing, number of baffles, pressure drop, lmtd, helix angle of tubes plays very.
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. There are probably heat exchanger in your office building which heat transfer from hot water to the ventilation. In this work, heat transfer coefficients of shell and helically coiled tube heat exchanger using al 2 o 3 water nanofluid were studied. Basic design methods of heat exchanger intechopen4. 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. John richard thome ltcm sgm epfl heat transfer heat exchanger design 1er mars 2008 4 41. Therefore the log mean temperature for a counter flow heat exchanger is larger than the log mean temperature for a similar parallel or. Pdhonline course m371 2 pdh shell and tube heat exchangers. Describes how counter flow is different from parallel flow. Nov 28, 2018 a heat exchanger is a device used to transfer heat between two or more fluids. Most likely you have knowledge that, people have look numerous times for their favorite books gone this solutions manual heat transfer, but stop occurring in harmful downloads.
Counter flow heat exchangers are the most efficient of the three types. It is therefore possible to heat or cool fluids or gases which have minimal energy levels. The simplest heat exchanger is one for which the hot and cold fluids move in the same or opposite directions. Heat exchangers jordan university of science and technology. Our main focus is to increase the efficiency of the parallel flow heat exchanger and on the basis of this, decide. Experimental study on parallel and counter flow configuration. With a plate type heat exchanger, the heat penetrates the surface, which separates the hot medium from the cold one very easily. A heat exchanger follows this principle in its endeavour to reach equalisation. A more detailed description of aircooled heat exchanger geometries is given refs. Pdf in this work, a modified analysis of a parallelflow plate heat exchanger that takes into. Parallel flow, counter flow, heat transfer coefficient, lmtd, effectiveness. Heattransfer characteristics of wet heat exchangers in. Counterflow has highest lmtd, for given ts therefore smallest.
In parallel flow heat exchangers, the two mediums enter the exchanger at the same. Aug 28, 2018 lets take the case when we want to extract the maximum amount of heat from a given hot stream. Pdf material selection and fluid flow analysis of parallel flow. Convective heat transfer from the outer tube wall to the outside fluid. Difference in counter heat exchanger and parallel flow heat.
The term heat exchanger applies to all equipment used to transfer heat between two streams. Jul 01, 2016 according to flow of fluids, the heat exchangers are classified into three categories. 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 calculations with the heat exchanger design equation require a value for the heat transfer rate, q, which can be calculated from the known flow rate of one of the fluids, its heat capacity, and the required temperature change. July 2016, volume 3, issue 7 jetir issn 2349 5162 numerical. Lets take the case when we want to extract the maximum amount of heat from a given hot stream.
Using this method, we will make efforts to improve the design of heat exchangers and optimize the shapes of distributors toward. Lmtd for parallel flow heat exchanger heat exchanger heat. Parallel, counter, or cross flow of hot and cold streams. We treat the heat exchanger as insulated around the outside so that the only heat transfer is between the two fluids. Lets assume we have a perfectly efficient, infinitely long heat exchanger with the same substance on each side, but one enters at 100 f and the other at 0 f.
However, the term is commonly used to equipment in which two process streams exchange heat with each other. Mar, 20 calculates the length of a concentric counter flow heat exchanger using the same parameters as in sizing a heat exchanger. Crossflow, parallel flow, and counterflow heat exchanger configurations are three examples. For a laminar flow in the channels, navierstokes equations are solved for the heat transfer and fluid flow in the channels. This study was done by changing the parallel flow configuration into counter flow configuration under laminar flow regime. Design and development of parallelcounter flow heat exchanger. Pdf performance charts for multipass parallel crossflow.
The figure below show heat exchanger schematics and the temperature profiles for both cocurrent and countercurrent desig. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the. This engineering calculator will determine a number of variables for the most common arrangements or flow paths within heat exchangers. For example, refrigerators use heat exchangers to heat transfer from your groceries to the surrounding air. If the flow pattern is more complex such as the case with most shell and tube heat. The materialprocess decision on a parallel flow heat exchanger. Pdf analysis of a parallelflow heat exchanger with a heat source. A maximum of up to ten heat exchanger passes were considered in. Heat exchanger is a device which provides a flow of thermal energy between two or more fluids at different temperatures.
The efficiency of a counter flow heat exchanger is due to the fact that the average t difference in temperature between the two fluids over the length of the heat exchanger is maximized, as shown in figure 4. Fire the boiler as per instructions in the boiler manual. Use to define total thermal resistance to heat transfer. The present work is directed towards the modeling of shell and tube parallel flow heat exchanger in solid works 2014 and setting up of flow simulation in solid works by inserting boundary. A heat exchanger can have several different flow patterns. Heat transfer l32 p2 temperatures for parallel and. Which conditions will you select, parallel flow or counter. Counter flow heat exchanger for cross flow and shellandtube heat exchangers. Why is a counter flow heat exchanger better than a parallel.
Heat transfer equation sheet heat conduction rate equations fouriers law. The simplest heat exchanger is one for which the hot and cold fluids move in the same or opposite directions in a concentric tube or doublepipe construction. Difference in counter and parallel flow heat exchanger. Note that in a counter flow 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. Design and fabrication of shell and tube heat exchanger. If there is an additional resistance either in series or in parallel, then replace with in all the above lumped ca. Heat exchanger theory and the heat exchanger design equation. The two most common heat exchanger design problems are those of rating and sizing. Heat exchangers are typically classified according to flow arrangement and type of construction.
Experimental investigation of parallel and counter flow heat. Temperature profiles in a counter flow and b parallel flow single pass heat exchangers. The results plotted on graph for lmtd vs discharge and lmtd vs efficiency. Parallel and counter flow designs heat exchangers engineers.
Cocurrent flow is rarely used in a singlepass heat exchanger, because, as inspection of figures 4. The log mean temperature difference lmtd is derived in all basic heat transfer texts. In this case, the two fluids enter the heat exchanger from the same end with a large temperature difference. Analysis of a counter flow parallelplate heat exchanger asee. Parallel flow heat exchanger the figure below shows a schematic of a parallel flow heat exchanger along with temperature distribution for the hot and cold fluids. Plate heat exchanger, how it works working principle hvac industrial engineering phx heat transfer duration. Counter flow heat exchangers are inherently more efficient than parallel flow heat exchangers because they create a more uniform temperature difference between the fluids, over the entire length of the fluid path. Tlm however, in process engineering practice most heat exchangers are not of this type, having several shell passes and tube passes. A heat exchanger can also be operated in counterflow, in which the two fluids flow in parallel but opposite directions. In other words, heat exchangers are used in both cooling and heating processes.
Reduction in air temperature happens in both parallel flow and counter flow arrangements, and increases the rate of heat transfer from the cooled water to the air. Pdf design and development of parallel counter flow. The second type is regenerative type, in which hot and cold fluids are in the same space which contain a matrix of materials which work alternately as source for heat flow. The first type of a heat exchanger is called the recuperative type, in which heat are exchanged on either side of a dividing wall by fluids.
Various types of fins and attachments are illustrated in fig. Previously developed matrix approach was employed to study the performance at each pass of the parallel cross flow heat exchanger. Access free solutions manual heat transfer solutions manual heat transfer thank you certainly much for downloading solutions manual heat transfer. We are intended to show the merits of spiral coiled heat exchanger to that of the conventional parallel type heat exchangers. In parallel flow heat exchangers, both the tube side fluid and the shell side fluid flow in same direction. Effectiveness, heat transfer, helical tube, turbulence, counter current i. Counter flow heat exchangers can allow the cold fluid to exit with a higher temperature than the exiting hot fluid. A counterflow heat exchanger will require less heat exchange surface area than a parallel flow heat exchanger for the same heat transfer rate and the same inlet and outlet temperatures for the fluids.
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