Heat Exchange Between Air and a Liquid Film Flowing Down Along a Profiled Surface

The laws of heat exchange between air and a liquid film flowing down along a solid surface with spherical dimples were investigated experimentally. Three cases of heat transfer were considered: quiescent air, air – liquid counter flow, or their cross flow. In all cases, a significant growth of the heat exchange intensity, especially at air – liquid cross flow, was observed. This is caused by the substantial turbulization of flow and mixing of liquid layers in the film. As a result, it was established that surface profiling (manufacture of dimples) under the optimal conditions leads to an increase in heat exchange intensity by an unexpended factor of 2.5 – 2.8 as compared with a smooth surface, other conditions being equal. The obtained experimental data were generalized in the form of dimensionless dependences Nu vs. Re. The best heat transfer surface can be recommended for use in different heat exchangers.

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EXERGY TRANSFER CHARACTERISTICS ON LOW TEMPERATURE HEAT EXCHANGERS

International Journal of Modern Physics B ◽

10.1142/s0217979207044846 ◽

2007 ◽

Vol 21 (18n19) ◽

pp. 3503-3505 ◽

Cited By ~ 2

Author(s):

S. Y. WU ◽

X. F. YUAN ◽

Y. R. Li ◽

L. PENG

Keyword(s):

Heat Transfer ◽

Heat Capacity ◽

Low Temperature ◽

Transfer Coefficient ◽

Heat Exchangers ◽

Cross Flow ◽

Counter Flow ◽

Temperature Heat ◽

Relevant Variables ◽

Exergy Transfer

By analyzing exergy transfer process of the low temperature heat exchangers operating below the surrounding temperature, the concept of exergy transfer coefficient is put forward and the expressions which involving relevant variables for the exergy transfer coefficient, the heat transfer units number and the ratio of cold to hot fluids heat capacity rate, etc. are derived. Taking the parallel flow, counter flow and cross flow low temperature heat exchangers as examples, the numerical results of exergy transfer coefficient are given and the comparison of exergy transfer coefficient with heat transfer coefficient is analyzed.

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Thermal Efficiency of the Cross Flow Heat Exchangers

Heat Transfer, Volume 1 ◽

10.1115/imece2006-13575 ◽

2006 ◽

Cited By ~ 8

Author(s):

Ahmad Fakheri

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Heat Transfer Rate ◽

Heat Exchangers ◽

Transfer Rate ◽

Cross Flow ◽

Algebraic Expression ◽

Counter Flow ◽

Optimum Heat ◽

Flow Heat

The heat exchanger efficiency is defined as the ratio of the actual heat transfer in a heat exchanger to the optimum heat transfer rate. The optimum heat transfer rate, qopt, is given by the product of UA and the Arithmetic Mean Temperature Difference, which is the difference between the average temperatures of hot and cold fluids. The actual rate of heat transfer in a heat exchanger is always less than this optimum value, which takes place in an ideal balanced counter flow heat exchanger. It has been 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. The function defining the efficiency of these heat exchangers is identical to that of a constant area fin with an insulated tip. This paper presents exact expressions for the efficiencies of the different cross flow heat exchangers. It is shown that by generalizing the definition of Fa, very accurate results can be obtained by using the same algebraic expression, or a single algebraic expression can be used to assess the performance of a variety of commonly used heat exchangers.

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Exergy Transfer Effectiveness on Heat Exchanger

Advanced Energy Systems ◽

10.1115/imece2006-13502 ◽

2006 ◽

Author(s):

Shuang-Ying Wu ◽

Xiao-Feng Yuan ◽

You-Rong Li ◽

Wen-Zhi Cui ◽

Liao Quan

Keyword(s):

Heat Transfer ◽

Heat Capacity ◽

Heat Exchanger ◽

Heat Exchangers ◽

Cross Flow ◽

Counter Flow ◽

Temperature Heat ◽

Relevant Variables ◽

Flow Heat ◽

Exergy Transfer

In this paper, the concept of exergy transfer effectiveness is put forward firstly and the expressions involving relevant variables for the exergy transfer effectiveness, the heat transfer units number and the ratio of cold and hot fluids heat capacity rate have been derived for the high and low temperature heat exchangers. Taking the parallel flow, counter flow and cross flow heat exchangers as examples, the numerical results of exergy transfer effectiveness are given and the comparison of exergy transfer effectiveness with heat transfer effectiveness is analyzed.

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Analisis Perbandingan Jenis Material Penukar Kalor Plat Datar Aliran Silang Untuk Proses Pengeringan Kayu

Jurnal Teknologi ◽

10.31479/jtek.v9i1.117 ◽

2021 ◽

Vol 9 (1) ◽

pp. 60-71

Author(s):

Abeth Novria Sonjaya ◽

Marhaenanto Marhaenanto ◽

Mokhamad Eka Faiq ◽

La Ode M Firman

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Flat Plate ◽

Heat Exchangers ◽

Fluid Dynamic ◽

Cross Flow ◽

Plate Heat ◽

Dry Air ◽

Copper Material ◽

Plate Type

The processed wood industry urgently needs a dryer to improve the quality of its production. One of the important components in a dryer is a heat exchanger. To support a durable heat transfer process, a superior material is needed. The aim of the study was to analyze the effectiveness of the application of cross-flow flat plate heat exchangers to be used in wood dryers and compare the materials used and simulate heat transfer on cross-flow flat plate heat exchangers using Computational Fluid Dynamic simulations. The results showed that there was a variation in the temperature out of dry air and gas on the flat plate heat exchanger and copper material had a better heat delivery by reaching the temperature out of dry air and gas on the flat plate type heat exchanger of successive cross flow and. overall heat transfer coefficient value and the effectiveness value of the heat exchanger of the heat transfer characteristics that occur with the cross-flow flat plate type heat exchanger in copper material of 251.74725 W/K and 0.25.

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Heat exchange of dynamic powder beds with a heat-transfer surface. II. A dust-laden gas flow

Journal of Engineering Physics and Thermophysics ◽

10.1007/bf02699057 ◽

1999 ◽

Vol 72 (1) ◽

pp. 7-10

Author(s):

D. S. Pashkevich ◽

V. N. Krasnokutskii ◽

V. B. Petrov ◽

V. L. Korolev

Keyword(s):

Heat Transfer ◽

Heat Exchange ◽

Gas Flow ◽

Heat Transfer Surface

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Heat Transfer Between Liquid Film Formed on the Inclined Dimpled Surface and Ambient Air

Volume 10: Heat and Mass Transport Processes, Parts A and B ◽

10.1115/imece2011-65042 ◽

2011 ◽

Author(s):

Vitalii Dubrovskii ◽

Aleksei Podvysotskii ◽

Aleksandr Shraiber ◽

Yaroslav Chudnovsky ◽

Aleksandr Kozlov

Keyword(s):

Heat Transfer ◽

Liquid Film ◽

Ambient Air ◽

Engineering Practice ◽

Transfer Enhancement ◽

Design Modification ◽

Surface Profiling ◽

Minimal Design ◽

Flow Turbulence ◽

Surface Increase

Heat transfer enhancement area attracts the close attention of the researchers and engineers worldwide for the last decades. The most popular techniques nowadays to enhance heat transfer from the surface is to extend it with the fins, studs, etc. or to profile it with the elements of artificial roughness, winglets, dimples, etc. Those types of surface enhancement allow improving the thermal efficiency of the heat transfer equipment with minimal design modification and without significant capital expenses. One of the interesting and promising techniques of the surface profiling is the formation on the surface the arrangement of spherical dimples, which generate intensive vortex structure near the surface, increase flow turbulence and, as a result, enhance heat and mass transfer between a profiled surface and a liquid (or gas) flowing over it [1–3]. In this connection, it is interesting to establish whether surface profiling will also enhance the heat transfer intensity between a liquid film on such a surface and ambient air. Unfortunately, authors were not able to find any publications on this subject in the open domain. At the same time, the investigation of this process could be of great interest for the engineering practice, in particular, for the cooling towers advancement. In the present work, the authors discuss some experimental results obtained for the different profile parameters and flow regimes.

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CFD analysis for counter flow in concentric tube heat exchangers

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i2.20.14772 ◽

2018 ◽

Vol 7 (2.20) ◽

pp. 250

Author(s):

Banoth Mohan ◽

V Ashok Kumar

Keyword(s):

Heat Exchange ◽

Heat Exchangers ◽

Associate Degree ◽

Cfd Analysis ◽

Sensible Heat ◽

Counter Flow ◽

Cooling Medium ◽

In Transit ◽

Parallel Stream ◽

Coaxial Tube

A device may be a device worked for the sensible heat exchange beginning with one liquid then onto the attendant, paying very little reference to whether or not the liquids square measure isolates by a powerful divider in order that they ne'er mix, or the liquids square measure particularly in touch. reliably get some data concerning in device progression is creating to form productive, traditionalist and stinting heat exchangers, where for the duration of the planet. Strengthening the function for this alteration wants associate degree association. In most up-to-date 5 years coaxial tube heat exchangers use unnatural convection to cut down the temperature of a operating liquid whereas raising the temperature of the cooling medium. The motivation driving this paper is to utilize ANSYS FLUENT12.1 programming and hand counts to interrupt down the temperature drops as a neighborhood of each straight speed and delta temperature and the way each modification with the opposite. every gleam money dealer show was worked in steps and examined in transit till the purpose that the instant that each parallel stream and counter stream heat money dealer models were created. The outcomes were thought of between every model and among parallel and counter stream with fouled funneling. Turbulent stream was conjointly impecunious down amidst the distinction within the shine exchangers to choose its impact on heat exchange. whereas clearly the fouled heat money dealer had a lower execution and during this manner cooled the operating liquid less, the execution of the counter heat money dealer out of the blue of the parallel heat money dealer.

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Failure Analysis of Heat Exchangers

10.31399/asm.hb.v11a.a0006813 ◽

2021 ◽

pp. 3-19

Author(s):

Dusan P. Sekulic

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Failure Analysis ◽

Thermal Energy ◽

Solid Surface ◽

Heat Exchangers ◽

Heat Transfer Surface ◽

Tubular Heat Exchanger ◽

Erosion Corrosion ◽

Different Temperatures

Abstract Heat exchangers are devices used to transfer thermal energy between two or more fluids, between a solid surface and a fluid, or between a solid particulate and a fluid at different temperatures. This article first addresses the causes of failures in heat exchangers. It then provides a description of heat-transfer surface area, discussing the design of the tubular heat exchanger. Next, the article discusses the processes involved in the examination of failed parts. Finally, it describes the most important types of corrosion, including uniform, galvanic, pitting, stress, and erosion corrosion.

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