Heat Transfer and Pressure Drop of Typical Air Cooler Finned Tubes

1985 ◽  
Vol 107 (1) ◽  
pp. 198-204 ◽  
Author(s):  
P. W. Eckels ◽  
T. J. Rabas
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Finned Tube ◽  
Tip Clearance ◽  
Published Data ◽  
Air Cooling ◽  
Base Thickness ◽  
Finned Tubes ◽  
Air Cooler ◽  
The Heat Transfer Coefficient

The heat transfer and pressure drop performance of heat exchangers fabricated from helically wrapped finned tubes with an equilateral triangular pitch arrangement are reported for one through five rows. Two finned tube types were tested, one with a “T” foot and the other with an overlapped “L” foot. The dimensions of both finned tubes were similar and were typical of those used in air-cooling applications. The tube diameter was 25.4 mm; the fin height was 15.87 mm; the fin number was 0.41/mm; and the fin-tip clearance was 6.35 mm. The fin base thickness was 0.38 mm and was tapered to half the base thickness at the fin outside diameter. No difference in the thermal performance of the two finned tube types could be detected. Both the heat transfer coefficient and pressure drop were found to increase with the number of tube rows. These results were then compared to other published data.

Heat Transfer and Pressure Drop Performance of Finned Tube Bundles

1985 ◽  
Vol 107 (1) ◽  
pp. 205-213 ◽  
Author(s):  
P. W. Eckels ◽  
T. J. Rabas
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Air Conditioning ◽  
High Heat ◽  
Finned Tube ◽  
Tip Clearance ◽  
Finned Tubes ◽  
Pin Fin ◽  
High Heat Transfer ◽  
Air Cooled Heat Exchanger

The heat transfer and pressure drop performance of two types of finned tubes used in the air-conditioning industry are reported for 14 different bundle configurations. Twelve of these configurations contained a new type of finned tube called K-Y and two contained a more conventional pin fin. A unique characteristic of all these configurations is zero or negative fin-tip clearances. A comparison of the performance of these air-conditioning type finned tubes with negative fin-tip clearance is then made with the performance of typical air-cooled heat exchanger tubes used in the process and power industries. Both the heat transferred and the pressure drop are substantially higher with the air-conditioning configurations; the heat transfer coefficient is superior even to plain tubes. The very high heat transfer performance is more the result of the negative fin-tip clearance than the fin shape or type.

Tube Banks Heat Transfer Enhancement Using Conical Fins

2010 ◽  
Author(s):  
Ignacio Carvajal-Mariscal ◽  
Florencio Sanchez-Silva ◽  
Georgiy Polupan
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Finned Tube ◽  
Hot Water ◽  
Experimental Results ◽  
Tube Bank ◽  
Finned Tubes ◽  
Tube Banks ◽  
Annular Fins

In this work the heat transfer and pressure drop experimental results obtained in a two step finned tube bank with conical fins are presented. The tube bank had an equilateral triangle array composed of nine finned tubes with conical fins inclined 45 degrees in respect with the tube axis. The heat exchange external area of a single tube is approximately 0.07 m2. All necessary thermal parameters, inlet/outlet temperatures, mass flows, for the heat balance in the tube bank were determined for different air velocities, Re = 3400–18400, and one constant thermal charge provided by a hot water flow with a temperature of 80 °C. As a result, the correlations for the heat transfer and pressure drop calculation were obtained. The experimental results were compared against the analytical results for a tube bank with annular fins with the same heat exchange area. It was found that the proposed tube bank using finned tubes with conical fins shows an increment of heat transfer up to 58%.

Study on Free Convection Heat Transfer in a Finned Tube Array

2015 ◽  
Vol 23 (01) ◽  
pp. 1550007 ◽  
Author(s):  
Ryoji Katsuki ◽  
Tsutomu Shioyama ◽  
Chikako Iwaki ◽  
Tadamichi Yanazawa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Finned Tube ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Finned Tubes ◽  
Air Cooled Heat Exchanger ◽  
The Heat Transfer Coefficient

We have been developing a free convection air cooled heat exchanger without power supply to improve economic efficiency and mechanical reliability. However, this heat exchanger requires a larger installation area than the forced draft type air cooled heat exchanger since a large heating surface is needed to compensate for the small heat transfer by natural convection. Therefore, we have been investigating a heat exchanger consisting of an array of finned tubes and chimney to increase the heat transfer coefficient. Since the heat transfer characteristics of finned tube arrays have not been clarified, we conducted experiments with a finned tube array to determine the relation between the configuration of finned tubes and the heat transfer coefficient of a tube array. The results showed that the average heat transfer coefficient increased with pitch in the vertical direction, and became constant when the pitch was over five times the fin diameter. The average heat transfer coefficient was about 1.4 times higher than that of a single finned tube in free space. The ratio of the average heat transfer coefficient of the finned tube array with chimney to that of a single finned tube was found to be independent of the difference in temperature between the tube surface and air.

scholarly journals THE METHOD OF CALCULATION AND ANALYSIS OF HEAT TRANSFER COEFFICIENT OF BIMETALLIC FINNED TUBES OF AIR COOLING UNITS WITH IRREGULAR EXTERNAL CONTAMINATION

2017 ◽  
Vol 60 (3) ◽  
pp. 237-255
Author(s):  
V. V. Dudarev ◽  
S. O. Filatаu ◽  
T. B. Karlovich
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
New Method ◽  
Constant Thickness ◽  
Air Cooling ◽  
Term Operation ◽  
Finned Tubes ◽  
Annular Layer ◽  
The Heat Transfer Coefficient

The article focuses on a new method of calculating heat transfer coefficient of bimetallic finned tubes of air coolers taking into account external operational pollution. In contrast to wellknown methods that use the assumption of a uniform distribution of operational contamination layer with a constant thickness over the entire surface of the fins in the present method being introduced it is assumed that the thickness of the pollution layer during long-term operation is changed irregularly. Under such conditions the thickness of the pollution layer at the base of the fins becomes much greater than at the rest of the finned surface. The suggested method is based on a mathematical model developed with the use of the method of electrothermal analogy, whereby the heat flow through the wall of the finned tube is considered as divided into two components, viz. through the annular layer of outside contamination adjacent to the base of the ribs, and through the remaining part of the external ribbed surface covered with a thin layer of pollution. Within the framework of the developed methodology a new method for determining the thermal resistance of the pollution layer, which is based on analytical solution of two dimensional problem of heat conduction in the annular layer has been created. With the use of this technique the influence of the degree of contamination of the intercostal space of the industrially manufactured bimetallic finned tubes on the heat transfer coefficient has been studied taking into account the intensity of heat transfer of air and the properties and composition of the pollutant for industrial manufactured bimetallic finned tubes. It is established that a layer thickness of the pollutant at the base of the ribs has the greatest influence on the heat transfer coefficient. This is due primarily to the change of actual coefficient of the fins. It is demonstrated that the heat conductivity of the external pollutant has a significant impact on the heat transfer coefficient when the heat exchanger functions in the mode of forced convection of air.

An Investigation of Heat Transfer and Pressure Drop Enhancement of Various Perforated Circular Finned Tubes at Different Tube Tilt Angles

2021 ◽  
pp. 10295-10338
Author(s):  
Yahya Yaser Shanyour AL-Salman, Ali Sabri Abbas
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Tilt Angle ◽  
Transfer Rate ◽  
Performance Criterion ◽  
Finned Tube ◽  
Finned Tubes ◽  
Global Performance

The thermal and flow performance of the circular annular finned tube heat exchanger with perforated fins were investigated numerically using ANSYS Fluent 2020 software, RNG k-e model with enhanced wall treatment, global performance criterion was introduced as evaluation factor of the heat exchanger performance, the parameters to be investigated were the number of holes, size of hole, tilt angle of the finned tube, fin height and spacing between fins. Agreement was found with literature that the tilt angle causes increase in heat transfer rate and increase in the pressure drop as well, but the change the global performance criterion as function to tilt angle depends on the fin heights, for higher fin heights the effective change of the pressure drop become greater than the increase in the heat transfer rate and the contrast occur in the cases of smaller fin heights, we have found that the perforation in tilted annular circular finned tubes causes an increase in the heat transfer rate and an enhancement in the total heat exchanger performance, increasing the number of holes will enhance the performance of the heat exchanger and the spacing increase reduces the heat exchanger performance.

Heat Transfer and Pressure Drop Characteristics of Finned Tube Banks in Heat Exchanger for Gas Turbine

2004 ◽  
Author(s):  
K. Kawaguchi ◽  
K. Okui ◽  
Y. Hasegawa
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Thermal Power ◽  
Finned Tube ◽  
Finned Tubes ◽  
Thermal Power Generation ◽  
Reduction Of Energy Consumption ◽  
Tube Banks

In recent years the requirement for reduction of energy consumption has been increasing to solve the problems of the global warming and the shortage of petroleum resources. For example in the power generation field, as the thermal power generation occupied 60% of the power generation demand, the improvement of the thermal efficiency is required considerably. This paper described the heat transfer and pressure drop characteristics of the finned tube banks used for the heat exchanger in the thermal power generation. The characteristics were clarified by testing the serrated finned tubes banks for improvement of higher heat transfer and the conventional spiral finned tube banks under the same test conditions. The equations to predict heat transfer coefficient and pressure drop which are necessary on design of the heat exchanger were proposed.

scholarly journals Numerical Analysis of Heat Transfer and Pressure Drop in Helically Micro-Finned Tubes

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 754
Author(s):  
Muhammad Ammar Ali ◽  
Muhammad Sajid ◽  
Emad Uddin ◽  
Niaz Bahadur ◽  
Zaib Ali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Thermal Performance ◽  
Finned Tube ◽  
Smooth Tube ◽  
Working Fluid ◽  
Finned Tubes

In this study, the pressure drop and heat transfer characteristics of smooth tube and internal helically micro-finned tubes with two different fin-to-fin height ratios i.e., equal fin height and alternating fin height, are computationally analysed. The tube with alternating fin height is analysed for proof of concept of pressure drop reduction. A single phase steady turbulent flow model is used with a Reynolds number ranging from 12,000 to 54,000. Water is used as working fluid with inlet temperature of 55 °C and constant wall temperature of 20 °C is applied. Friction factor, heat transfer coefficient, Nusselt number, and Thermal Performance Index are evaluated and analysed. The numerical results are validated by comparison with the experimental and numerical data from literature. The results showed that the thermal performance is enhanced due to helically finned tube for a range of Reynolds numbers, but at the expense of increased pressure drop as compared to a smooth tube. The helically finned tube with alternating fin heights showed a 5% decrease in friction factor and <1% decrease in heat transfer coefficient when compared with the equal fin heights tube, making it a suitable choice for heat transfer applications.

Inspection Method of Finned Tube and Finned Heat Exchanger

2021 ◽  
Author(s):  
Ju Ding ◽  
Min Zhang ◽  
Shuhong Liu ◽  
Shenghui Wang ◽  
Jielu Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Eddy Current ◽  
Heat Exchangers ◽  
Finned Tube ◽  
Air Cooling ◽  
Finned Tubes ◽  
Detection Technology ◽  
Pressure Test ◽  
Current Detection

Abstract The finned tube heat exchanger is one of the earliest and most successful discoveries in the process of improving tube heat exchange. This method is still the most widely used of all kinds of tube heat transfer surface enhancement heat transfer methods. It is not only suitable for single-fin tube heat exchangers, which are widely used in power, chemical, petrochemical, air-conditioning engineering and refrigeration engineering. Conventional heat exchanger with smooth tubes can be inspected through the pressure test during the manufacturing process. Finned tubes and finned heat exchangers with inner thread structure have some difficult to pass the water pressure test. The same situation exists in regular inspections. Due to structural reasons, it is difficult to carry out regular surface inspections[1]. For these two situations, two different testing methods are required to ensure quality. This article introduces in detail the methods of inspecting finned tubes and finned heat exchangers. Hierarchical comparison of alternatives in hydrostatic testing project, and the eddy current detection technology of the finned tube under the condition of in-service air cooling. The far-field eddy current method is chosen for inspection. And by comparing the standard sample tube, it is mainly used to adjust the sensitivity of the eddy current detector and ensure the accuracy of the test results[2]. The results show that the eddy current detection technology can be more accurate and reliable. The corrosion of the finned tube under service air cooling is detected, and a reliable basis is provided for judging the use of the finned tube and finned heat exchanger[3].

Comparison Between Numerical and Experimental Gas Side Heat Transfer and Pressure Drop of a Tube Bank With Solid and Segmented Circular I-Fins

2012 ◽  
Author(s):  
Rene Hofmann ◽  
Heimo Walter
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Tube Bundle ◽  
Three Dimensional ◽  
Finned Tube ◽  
Three Dimensional Model ◽  
Finned Tubes ◽  
Numerical Predictions ◽  
Staggered Arrangement ◽  
Flow Experiments

In the present work, a comparison between numerical and experimental gas side heat transfer and pressure drop for a tube bundle with solid and segmented circular finned tubes in a staggered arrangement is investigated. For the numerical simulations a three dimensional model of the finned tube are applied. Renormalization group theory (RNG) based k–ε turbulence model was used to calculate the turbulent flow. Experiments have been carried out to validate the numerical predictions. The numerical results for the Nu-number and pressure drop coefficient show a good agreement with the data from measurement. A comparison between solid and segmented finned tubes from the global calculation of the Nu-numbers within the analyzed Re-range shows an enhancement by applying segmented finned tubes rather than finned tubes with solid fins.

Experimental and Numerical Investigation of the Gas Side Heat Transfer and Pressure Drop of Finned Tubes—Part II: Numerical Analysis

2012 ◽  
Vol 4 (4) ◽  
Author(s):  
Rene Hofmann ◽  
Heimo Walter
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Numerical Study ◽  
Three Dimensional ◽  
Finned Tube ◽  
Renormalization Group Theory ◽  
Tube Material ◽  
Finned Tubes ◽  
Steady State Temperature ◽  
Volume Method

The heat transfer and pressure drop behavior of segmented circular and helical as well as solid finned tubes are investigated in a three-dimensional numerical study. The simulation is carried out using a finite volume method for calculating the steady-state temperature and flow field of the fluid as well as the temperature distribution of the tube material. For modeling the turbulence, the k-ε turbulence model based on the renormalization group theory (RNG) is used to resolve the near-wall treatment between adjacent fins. All simulations are performed in the Re range between 3500 ≤ Re ≤ 50,000. The influence of Reynolds number and fin geometry (segmented or solid and circular or helical) on the local and global averaged heat transfer and pressure drop was studied. A comparison between solid and segmented finned tube has shown that the heat transfer and pressure drop for the segmented finned tubes is higher. The numerical results are compared with experimental data.

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