The flow in a rod baffle heat exchanger is parallel to the tubes, and flowinduced vibrations are virtually eliminated by the baffle support of the tubes. A counter flow heat exchanger is the most efficient flow pattern of the three. Experimental study on parallel and counter flow configuration of a. Parallel flow heat exchangers are rarely employed due to their requirement of large surface area for heat transfer. Effectiveness and efficiency analysis of parallel flow and. A counterflow heat exchanger is the most efficient flow pattern of the three.
The resulting temperature difference will be compared and be determined as a function of the inlet velocity and inlet temperatures. Comparative analysis of parallel and counter flow heat. Keoliana the pennsylvania state university, graduate program in acoustics and applied research laboratory, p. T2 represent the temperature difference at each end of the heat exchanger, whether parallel flow or counterflow. However, the nearly constant wall temperature is a characteristic of the parallel flow heat exchanger e. The simplest heat exchanger is one for which the hot and cold fluids move in the same or opposite directions. Heat exchangers are typically classified according to flow arrangement and type of construction. Heat exchangers are used widely in many industries for heat recovery or cooling purposes. The basic disturbance considered is a temperature step or a flow rate step on the disturbed fluid. 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.
The notes are intended to describe the three types of heat transfer and provide. The total heat transfer rate between the two fluids can be expressed. Parallel flow heat exchanger in parallel flow heat exchangers, the two mediums enter the exchanger at the same end, and travel in parallel to one. An expansion of this approach has been proposed hen 97 and successfully applied for responses in exchanged heat power, q. Flow arrangement parallel, counter, or cross flow of hot and cold streams mixed or unmixed ideal limiting cases of actual flow conditions with partial degrees of mixing type of construction ex. Comparison of heat exchanger types each of the three types of heat exchangers parallel, cross and counter flow has advantages and disadvantages.
Heat exchanger introduction use to transfer thermal energy from a hot fluid to a cold fluid classified according to. Author links open overlay panel chulin yu a haiqing zhang a min zeng b ruojin. A heat exchanger can also be operated in counterflow, in which the two fluids flow in parallel but opposite directions. Why counter flow heat exchangers are more efficient.
Numerical study on turbulent heat transfer performance of. Ntu method relates the effectiveness to the number of transfer units ntu of the heat transfer process and the ratio of the heat capacity rates c, defined as. For example, refrigerators use heat exchangers to heat transfer from your groceries to the surrounding air. The present work is directed towards the modeling of shell and tube parallel flow heat exchanger in solid.
Heat transfer equation sheet heat conduction rate equations fouriers law. Jarullah 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. If the flow pattern is more complex such as the case with most shell and tube heat exchangers, then a correction factor term is used and the. Two types of flow arrangement are possible in a doublepipe heat exchanger. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the. 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. 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. Introduction to engineering heat transfer these notes provide an introduction to engineering heat transfer. Equation is used when simple counter or cocurrent flows exist. Counter flow heat exchanger for cross flow and shellandtube heat exchangers. This study was done by changing the parallel flow configuration into counter flow configuration under laminar flow regime.
Effectiveness of parallel plate heat exchangers in thermoacoustic devices ray scott wakeland and robert m. 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. Lets take the case when we want to extract the maximum amount of heat from a given hot stream. It leads to the lowest required heat exchanger surface area because the log mean temperature drop is the highest for a counterflow. Therefore, the counterflow heat exchanger is usually preferable.
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. Tm is the log mean temperature difference given as t t. Three basic types of heat exchanger the simple parallel or counter. In this work, heat transfer coefficients of shell and helically coiled tube heat exchanger using al 2 o 3 water nanofluid were studied. Whats the difference between parallel flow, counter flow.
The flow in a heat exchanger can be arranged as parallel flow, counter flow, and cross flow. Design and development of parallel counter flow heat exchanger. Cfd analysis and performance of parallel and counter flow. 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. This paper developed a numerical model to simulate a counter flow parallel heat exchanger.
Counterflow, parallel flow, and crossflow are common heat exchanger types. The main difference is that the tubeside fluid enters the exchanger at. 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. The term exchanger applies to all equipment used to transfer heat between two. Heat exchanger transfer thermal energy from one medium to another. But of the three, the counter flow heat exchanger design is the most efficient when comparing heat transfer rate per unit surface area. It leads to the lowest required heat exchanger surface area because. 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. Temperature profiles in a counter flow and b parallel flow single pass heat exchangers. Pdf design and development of parallel counter flow. In this work, heat transfer coefficients of shell and helically coiled tube heat exchanger using al2o3 water nanofluid were studied. 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 materialprocess decision on a parallel flow heat exchanger design. Future scope the concept of entropy generation analysis can also be applied in the above analysis. John richard thome ltcm sgm epfl heat transfer heat exchanger design 1er mars 2008 4 41. Pdf design and development of parallel counter flow heat. Heat transfer processes set limits to the performance of aerospace components and systems and the subject is one of an enormous range of application. A heat exchanger can have several different flow patterns. Cross flow heat exchanger mixedunmixed solid curves. Experimental analysis of performance of heat exchanger. If there is an additional resistance either in series or in parallel, then replace with in all the above lumped ca. Counter flow heat exchangers are the most efficient of the three types. Therefore, the results of the heat transfer and the pressure drop characteristics in function of changing the flow of working fluids are presented below. Therefore, it can not be classified as a compact heat exchanger. 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. A test is conducted to determine the overall heat transfer coefficient in an automotive radiator that is a compact cross flow watertoair heat exchanger with both fluids air and water unmixed.
Pdf material selection and fluid flow analysis of parallel flow. However, there are applications where parallel flow has its benefits, such as when limiting the transfer of heat. Why is a counter flow heat exchanger better than a. E with combining the last three equations, we get two expressions for. 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. Difference in counter and parallel flow heat exchanger. Counter flow, parallel flow, and cross flow are common heat exchanger types. When the fluids enter and leave at the same end the arrangement is parallel flow, whereas in the counterflow configuration, the. The general function of a heat exchanger is to transfer heat from one fluid to another. Parallel flow to tubes platefin tubefin ordinary separating wall heat pipe wall rotary fixedmatrix. Thermal analysis of heat exchangers with parallel flow. Analysis of a counter flow parallelplate heat exchanger asee. Find, read and cite all the research you need on researchgate. Pdf analysis of a parallelflow heat exchanger with a heat source.
In the simplest heat exchanger, two fluids one cold and one hot move in the same or opposite directions in a concentric tube configuration. This heat exchanger consists of two concentric pipes of different diameters. In general, parallel flow heat exchangers considered less efficient than counter flow heat exchangers in terms of transferring heat from one fluid to another. Heat exchangers can be classified according to flow arrangement and the construction features.
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