A Preliminary Method for Estimating the Effective Plume Chimney Height above a Forced-Draft Air-Cooled Heat Exchanger Operating under Natural Convection

2002 ◽  
Vol 23 (3) ◽  
pp. 3-12 ◽  
Author(s):  
C. M. Chu
Keyword(s):  
Natural Convection ◽  
Heat Exchanger ◽  
Forced Draft ◽  
Air Cooled Heat Exchanger

Simulation of Effective Plume-Chimney Above Natural Draft Air-Cooled Heat Exchangers

2017 ◽  
Author(s):  
Christopher Chi-Ming Chu ◽  
Robert Hieng Yik Tie ◽  
Md. Mizanur Rahman
Keyword(s):  
Natural Convection ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Industrial Scale ◽  
Test Rig ◽  
Face Area ◽  
Scale Test ◽  
Forced Draft ◽  
Air Cooled Heat Exchanger

Effective Plume-Chimney Height (EPCH) was a factor engineers used to design and analyse the performance of natural convection in air-cooled heat exchangers particularly in the event of power outage. To date the number of papers in the open literature presenting data on natural convection performance of air-cooled heat exchangers is scarce. The aim of this study is to corroborate the experimental results and theoretical predictions of Effective Plume-Chimney Height (EPCH) using Computational Fluid Dynamics (CFD) in a laboratory-scale air cooled heat exchanger of 457mm × 457mm face area and an industrial-scale test rig of 2.4m × 6.0m face area forced draft air-cooled heat exchanger comprising of a bundle with 4 rows of annular finned tubes in staggered formation operating under natural convection. The CFD software Phoenics 2015 was employed to simulate the electrically-heated air-cooled heat exchanger fitted with a top screen which was built to study the aerodynamics of natural convection of air-cooled heat exchangers. The CFD geometry arrangement and dimensions were schematic in nature, where errors introduced were considered reasonably negligible. The laboratory-scale exchanger model experimental pressure drop data was found to have an insignificant effective plume-chimney height, as predicted by a theoretical equation. It was found that EPCH values calculated from CFD results agree closely to within −0.11m and +0.06m with both experiments and the theoretical prediction, confirming the same conclusion reached in an earlier report. However, for an industrial-scale test rig (ITR) in forced draft mode of large face dimensions the EPCH had been found to be non-negligible in an earlier work. Significant values of theoretical effective plume-chimney height were inserted in the heat transfer and pressure drop simulation that appeared to yield results that agreed with the experimental heat loads. The CFD simulations on the ITR have confirmed the existence of significant effective plume-chimney heights at more than 100 percent of the bundle depth, or the chimney height. The implication is that a solid-walled chimney can appear to have an efficiency of more than 100 per cent, if cold inflow can be prevented or the penetration to the central core hindered. Since the validation of the existence of EPCH by CFD here has used only a set of data from a single source, it is worthwhile to produce more experimental data and analysis to establish the concept for better predictions of air-cooled heat exchanger natural convection performance.

scholarly journals Experimental Study for Counter to Cross Flow Air Cooled Heat Exchanger in Concentric Tube using Rectangular Copper Fins Spacing with Internal Spiral Grooving

2021 ◽  
pp. 203-208
Author(s):  
Rakesh Kumar Tiwari ◽  
Ajay Singh ◽  
Parag Mishra
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Forced Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cross Flow ◽  
Variable Number ◽  
Air Cooled Heat Exchanger

In this manuscript we have presented eight variation of Air-Cooled Heat Exchanger (ACHE) design with internal spiral grooving, all of them are having variable number of rectangular copper fins with different distances between the fins. In the proposed design we get the value of heat transfer rate of a counter to cross flow ACHE is 7833.77 watt, 4068.13 watt, 2736.95 watt, 2161.49 watt, 1802.89 watt, 1546.44 watt, 1336.51 watt and 1165.74 watt in natural convection (without fan) for 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm and 4.0 cm respectively. Then again, value of rate of heat transfer in forced convection (with fan) are 8007.46 watt, 4084.81 watt, 2754.69 watt, 2205.98 watt, 1809.24 watt, 1555.39 watt, 1352.88 watt and 1172.78 watt for 0.5 cm, 1.0 cm, 1.5cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm and 4.0 cm respectively.

Numerical Investigation of the Performance of a Forced Draft Air-Cooled Heat Exchanger

2017 ◽  
Author(s):  
Ruan A. Engelbrecht ◽  
Johan Van der Spuy ◽  
Chris J. Meyer ◽  
Albert Zapke
Keyword(s):  
Heat Exchanger ◽  
Axial Flow ◽  
Disk Model ◽  
Validation And Verification ◽  
Wind Speeds ◽  
Power Stations ◽  
Modelling Techniques ◽  
Computational Fluid Dynamics Cfd ◽  
Forced Draft ◽  
Air Cooled Heat Exchanger

This paper details the design, validation and verification of two implicit modelling techniques used to model an Air-Cooled Condenser (ACC) in the computational fluid dynamics (CFD) code environment of OpenFOAM (Open Source Field And Manipulation). The actuator disk model was chosen as the axial flow fan model and the heat exchanger model was implemented as an A-frame, or Delta frame, heat exchanger commonly found on power stations. Both models were validated and verified. A 30 fan ACC was verified against previous literature. The results for all validation and verification procedures showed good agreement with respective data. Three different fan configurations in an ACC were compared at different wind speeds namely the A-fan, B2a-fan and a Combined ACC. The study showed small differences between ACCs with regard to fan and thermal performance. However, the B2a-fan ACC consumed 20% less power than the A-fan ACC and 3–10% less power than the Combined ACC. This performance increase was most prominently show-cased by the increased heat-to-power ratio with the B2a-fan exhibiting heat-to-power ratios of 110 W/W compared to 96 W/W for the A-fan.

scholarly journals Experimental and Theoretical Investigation of the Natural Convection Heat Transfer Coefficient in Phase Change Material (PCM) Based Fin-and-Tube Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 716
Author(s):  
Saulius Pakalka ◽  
Kęstutis Valančius ◽  
Giedrė Streckienė
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Energy Storage ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

Latent heat thermal energy storage systems allow storing large amounts of energy in relatively small volumes. Phase change materials (PCMs) are used as a latent heat storage medium. However, low thermal conductivity of most PCMs results in long melting (charging) and solidification (discharging) processes. This study focuses on the PCM melting process in a fin-and-tube type copper heat exchanger. The aim of this study is to define analytically natural convection heat transfer coefficient and compare the results with experimental data. The study shows how the local heat transfer coefficient changes in different areas of the heat exchanger and how it is affected by the choice of characteristic length and boundary conditions. It has been determined that applying the calculation method of the natural convection occurring in the channel leads to results that are closer to the experiment. Using this method, the average values of the heat transfer coefficient (have) during the entire charging process was obtained 68 W/m2K, compared to the experimental result have = 61 W/m2K. This is beneficial in the predesign stage of PCM-based thermal energy storage units.

Air-cooled heat exchanger applied to external rotary kiln wall in forced and natural draft

2017 ◽  
Vol 154 ◽  
pp. 517-525 ◽  
Author(s):  
F. Huchet ◽  
M. Piton ◽  
A. Del Barrio ◽  
O. Le Corre ◽  
B. Cazacliu
Keyword(s):  
Heat Exchanger ◽  
Rotary Kiln ◽  
Natural Draft ◽  
Air Cooled Heat Exchanger

Optimization Design of Refuse-Incinerating Power Plant With Air-Cooled Heat Exchanger

2013 ◽  
Vol 35 (6-8) ◽  
pp. 711-720
Author(s):  
Dongjie Zhang ◽  
Qin Chen ◽  
Qiuwang Wang ◽  
Xiangyang Xu
Keyword(s):  
Heat Exchanger ◽  
Power Plant ◽  
Optimization Design ◽  
Air Cooled Heat Exchanger

scholarly journals Numerical Analysis on Natural Convection Heat Transfer in a Single Circular Fin-Tube Heat Exchanger (Part 1): Numerical Method

Entropy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 363 ◽  
Author(s):  
Jong Hwi Lee ◽  
Jong-Hyeon Shin ◽  
Se-Myong Chang ◽  
Taegee Min
Keyword(s):  
Natural Convection ◽  
Heat Exchanger ◽  
Rayleigh Number ◽  
Numerical Method ◽  
Stokes Equations ◽  
Convection Heat Transfer ◽  
Boussinesq Approximation ◽  
Tube Heat Exchanger ◽  
Fin Tube ◽  
Rayleigh Numbers

In this research, unsteady three-dimensional incompressible Navier–Stokes equations are solved to simulate experiments with the Boussinesq approximation and validate the proposed numerical model for the design of a circular fin-tube heat exchanger. Unsteady time marching is proposed for a time sweeping analysis of various Rayleigh numbers. The accuracy of the natural convection data of a single horizontal circular tube with the proposed numerical method can be guaranteed when the Rayleigh number based on the tube diameter exceeds 400, which is regarded as the limitation of numerical errors due to instability. Moreover, the effective limit for a circular fin-tube heat exchanger is reached when the Rayleigh number based on the fin gap size ( Ra s ) is equal to or exceeds 100. This is because at low Rayleigh numbers, the air gap between the fins is isolated and rarely affected by natural convection of the outer air, where the fluid provides heat resistance. Thus, the fin acts favorably when Ra s exceeds 100.

Water redistribution among various sectors to avoid freezing of air-cooled heat exchanger

2019 ◽  
Vol 141 ◽  
pp. 294-309 ◽  
Author(s):  
Yanqiang Kong ◽  
Weijia Wang ◽  
Lijun Yang ◽  
Xiaoze Du ◽  
Yongping Yang
Keyword(s):  
Heat Exchanger ◽  
Water Redistribution ◽  
Air Cooled Heat Exchanger
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