Crossflow and Heat Transfer Characteristics Across a Cam-Shaped Tube Bank: A Numerical Study (original) (raw)
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2020
One of the most common equipment that are used in all types of power plants and engines are heat exchangers. FTHEs are widely used in various applications, e.g. ventilating and air-conditioning systems, refrigeration, and car radiators etc. as they own high performance and low space requirement. In this study, the characteristics of the forced convective heat transfer and pressure drop in both inline and staggered arrangements of circular fin cross flow heat exchanger are Experimentally investigated and the effect of mass flow rate on parameters such as Nusselt number, overall heat transfer coefficient, and heat transfer is studied. The air was blown with the velocities 0.2m/s, 1m/s, and 2.3m/s and the corresponding changes in inlet and outlet temperature of hot and cold air was measured. It was found that the Heat transfer (Q), Heat transfer coefficient(h), and Nusselt number(Nu) all increase with the increase in mass flow rate for both the inline and staggered arrangement and inli...
Heat Transfer and Fluid Flow Characteristic in banks Flat Tubes, 2009
In this research a study effect of the length ratio (L/Da) and the height ratio (H/Da) for banks flat tube heat exchanger In-Line and staggered arrangement on force convection heat transfer and friction coefficient by (Fluent-CFD) numerical program. The governing equations (mass, momentum and energy) are solving by using Finite Volume (Fluent-CFD) software for considering steady state, two dimensional, at constant heat flux with Reynold’s number (100≤Re≤8000). The results show that increasing (H/Da), (L/Da) lead to decreasing friction coefficient and enhancement of (Nu) is at (H/Da=2) for all (L/Da) values Inline arrangement and at (H/Da =2, L/Da =5) for staggered arrangement.
Heat Transfer and Fluid Flow Characteristic in banks Flat Tubes
Tikrit Journal of Engineering Sciences
In this research a study effect of the length ratio (L/Da) and the height ratio (H/Da) for banks flat tube heat exchanger In-Line and staggered arrangement on force convection heat transfer and friction coefficient by (Fluent-CFD) numerical program.The governing equations (mass, momentum and energy) are solving by using Finite Volume (Fluent-CFD) software for considering steady state, two dimensional, at constant heat flux with Reynold’s number (100≤Re≤8000).The results show that increasing (H/Da), (L/Da) lead to decreasing friction coefficient and enhancement of (Nu) is at (H/Da=2) for all (L/Da) values In-line arrangement and at (H/Da =2, L/Da =5) for staggered arrangement.
Heat Transfer-Asian Research, 2019
Heat transfer coefficients and pressure drop are studied experimentally for airflow over aligned round and flattened tube configurations. The Reynolds number is based on the outer diameter of the round tube or the outside transverse diameter of the flattened tube, which is used for various flows, ranging from 133 to 800 with a constant input heat flux. In the present work, a total of 30 samples of round and flattened tubes heat exchangers with three transverse pitches, 2.0, 3.0, and 4.5, were studied to investigate their thermal performance. The results indicate that the relative gain in the overall Nusselt number is about 32.5 to 60.6% in flattened tubes, while the reduction range in the friction factor is about 11 to 30.6%. Correlations are proposed for the overall Nusselt number, friction factor, and Colburn j-factor for both round and flattened tube banks. A higher value means that a deviation error of 9.9% in the round tube banks and 10.1% in the flattened tube banks are expected. In addition, the best value for thermal performance for the flattened tube bundle was found to be coincident with a smaller Reynolds number.
Numerical Investigation of Thermal-Flow Characteristics in Heat Exchanger with Various Tube Shapes
Applied Sciences, 2021
In this study, eight configurations of oval and flat tubes in annular finned-tube thermal devices are examined and compared with the conventional circular tube. The objective is to assess the effect of tube flatness and axis ratio of the oval tube on thermal-flow characteristics of a three-row staggered bank for Re (2600 ≤ Re ≤ 10,200). It has been observed that the thermal exchange rate and Colburn factor increase according to the axis ratio and the flatness, where O1 and F1 provide the highest values. O1 produces the lowest friction factor values of all the oval tubes at all Re, and F4 gives 13.2–18.5% less friction than the other tube forms. In terms of performance evaluation criterion, all of the tested tubes outperformed the conventional circular tube (O5), with O1 and F1 obtaining the highest values. The global performance criterion of O1 has been found to be 9.6–45.9% higher as compared to the other oval tube geometries at lower values of Re, and the global performance criter...
Renewable and Sustainable Energy Reviews, 2015
ABSTRACT The heat exchangers have a widespread use in industrial, transportation as well as domestic applications such as thermal power plants, means of transport, air conditioning and heating systems, electronic equipment and space vehicles. The key objectives of this article are to provide an overview of the published works that are relevant to the tube banks heat exchangers. A review of available and display that the heat transfer and pressure drop characteristics of the heat exchanger rely on many parameters. Such parameters as follows: external fluid velocity, tube configuration (in-line/staggered, series), tubes rows, tube spacing, fin spacing, shape of tubes, etc. The review also shows the finned and un-finned tube configurations heat exchangers. The important correlations for thermofluids in tube banks heat exchangers also discussed. The optimum spacing of tube-to-tube and fin-to-fin with fixed size (i.e., area, volume) with the maximum overall heat conductance (heat transfer rate) were summarized in this review. In addition, the few studies show the effect of tube diameter in a circular shape compared with elliptic tube shape. Overall, the heat transfer coefficient and pressure drop increases with increasing fluid velocity regardless the arrangement and shape of the tube. In the meantime, the other shape of tubes (such as flat or flattened) for finned and un-finned with the optimum design needs more research and investigation due to have lesser air-side pressure drop and improved air-side heat transfer coefficients. They have putted some the significant conclusions from this review.KeywordsHeat exchangerFlat tubeIn-line/staggered configurationsOptimum spacingThermofluids characteristics
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/cfd-analysis-of-heat-exchanger-over-a-staggered-tube-bank-for-different-angle-arrangement-of-tube-bundles https://www.ijert.org/research/cfd-analysis-of-heat-exchanger-over-a-staggered-tube-bank-for-different-angle-arrangement-of-tube-bundles-IJERTV2IS1445.pdf The modelling and performance prediction of a cross flow over a tube bundle using computational fluid dynamics (CFD) is the emerging development. The present work report, the analysis of pressure drop and heat transfer characteristics over a staggered tube bank heat exchanger with different tube bundle arrangements by using Fluent Software. The model was set up for a different mass flow rate over a tube bank and hence different Reynolds numbers and friction factor were studied. To improve hydraulic and thermal performance of heat exchanger we have simulated for the different angle arrangements i.e. 30°, 45° and 60°. The pressure drop results from the CFD simulation are compared with that obtained from the correlation.
Heat Transfer Engineering, 2019
Three-dimensional numerical simulations are successfully carried out on thermo-hydraulic characteristics of a new plain fin-and-elliptical tube (PFET) heat exchanger with innovative types of tube-banks, namely-a slotted elliptical tube-bank (SETB) (Case B and Case C) and a slotted annular elliptical tube-bank (SAETB) (Case D and Case E). The new PFET heat exchanger contains elliptical cross-sectioned tubes that create narrow slots oriented in the streamwise or/and spanwise direction. The investigation on the effects of different shape tube-banks on the air-side heat transfer and fluid flow characteristics in the new PFET heat exchanger was performed using the ANSYS CFXV R package. The objectives of this investigation are to determine an optimal staggered tube-bank configuration for augmenting heat transfer rates with minimal pressure drop penalties, and compare the results against traditional non-slotted elliptical tube-bank heat exchangers. The averaged heat transfer rate of the SETB/SAETB heat exchanger is more than 15% greater than that of the traditional nonslotted elliptical tube heat exchanger. The overall performance evaluation criteria, estimated in terms of the area goodness factor and volume goodness factor for enhanced cases (SETBs/ SAETBs), were higher than there found by a non-slotted elliptical tube-bank case. Overall, the computational results showed that the Case D causes an appreciable increase of the heat transfer rate without a pressure drop penalty.
Numerical computation of flow and heat transfer in finned and unfinned tube banks
International Journal of Heat and Mass Transfer - INT J HEAT MASS TRANSFER, 1987
A finite volume numerical scheme is utilized to predict fluid flow and heat transfer characteristics in inline tube banks. The effect of equipping the tubes with longitudinal fins on the pressure drop and heat transfer is studied. The governing equations for t&rid Row and heat transfer are numerically solved, with the assumption of periodic, fully developed flow. The numerical methodology utilizes the stepped boundary technique to approximate the tube surface. The tubes are maintained at a constant temperature, and the calculations are carried out for laminar flow and for a large range of Reynolds and Prandtl numbers. The results for the unfinned tube case are compared with previously published experimental data. The numerical results agree well with the experimental measurements.
AN EXPERIMENTAL STUDY OF AIR FLOW AND HEAT TRANSFER OVER IN–LINE FLAT TUBE BANK
An experimental study was made to investigate heat transfer and air flow around the flat tubes of in-line flat tube banks with laminar forced convection. Measurements were conducted for sixteen tubes in the flow direction; four rows of four tubes, three air velocities (0.6, 0.8 and 1.0 m/s) and Reynolds numbers Re Dh = 527, 703 and 880, where D h is the hydraulic diameter of the tube. The total heat flux supplied in all the tubes was 968, 2259 and 3630 W/m 2 , respectively. The study results indicate that the average Nusselt number of all the flat tubes increased by 23.7%–36.7% with Reynolds numbers varying from 527 to 880 with fixed heat flux; also the average Nusselt number increased by 11.78%–23.75% at varying heat fluxes of 968, 2259 and 3630 W/m 2 , respectively at Reynolds number Re = 703. In addition, the pressure drop decreased with the increase of Reynolds number. The Nusselt number–Reynolds number correlation was found to be 2 1 C Nu C Re and the correlation yielded good predictions of the measured data with the mean error R 2 = 99.2%.