Optimal Design of Tube Banks in Crossflow Using Entropy Generation Minimization Method

Khan, Waqar Ahmed; Culham, Richard; Yovanovich, M. M.

doi:10.2514/6.2006-599

Cited by 10 publications

(8 citation statements)

References 24 publications

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“…This correlation was originally presented in graphical form, listing the Euler number for different configurations combined with a set of power-law fitted curves. Khan et al [51] digitized the graphical forms and performed a data reduction resulting in a single set of equations to determine the pressure drop of staggered and inline tube bundles. These equations (for an inline bundle with ) were used to evaluate the pressure drop.…”

Section: Test Set-up Benchmarkmentioning

confidence: 99%

Thermo-hydraulic study of a single row heat exchanger consisting of metal foam covered round tubes

T’Joen

Jaeger

Huisseune

et al. 2010

International Journal of Heat and Mass Transfer

114

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Open cell metal foam is a novel engineering material that offers an interesting combination of materials properties from a heat exchanger point of view such as a high specific surface area, tortuous flow paths for flow mixing and low weight. A new heat exchanger design with metal foams is studied in this work, aimed at low airside pressure drop. It consists of a single row of aluminum tubes covered with thin layers (4-8 mm) of metal foam. Through wind tunnel testing the impact of various parameters on the thermo-hydraulic performance was considered, including the Reynolds number, the tube spacing, the foam height and the type of foam. The results indicated that providing a good metallic bonding between the foam and the tubes can be achieved, metal foam covered tubes with a small tube spacing, small foam heights and made of foam with a high specific surface area potentially offer strong benefits at higher air velocities (> 4 m/s) compared to helically finned tubes. The bonding was done by conductive epoxy glue and was found to have a strong impact on the final results, showing a strong need for a cost-effective and efficient brazing process to connect metal foams to the tube surfaces.

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Section: Test Set-up Benchmarkmentioning

confidence: 99%

Thermo-hydraulic study of a single row heat exchanger consisting of metal foam covered round tubes

T’Joen

Jaeger

Huisseune

et al. 2010

International Journal of Heat and Mass Transfer

114

View full text Add to dashboard Cite

show abstract

“…where the entropy generation rate in the heat sink can be obtained by following Bejan [28] and Khan et. al [20][21][22] and applying the laws of conservation of mass and energy with the entropy balance and can be written aṡ…”

Section: Model Developmentmentioning

confidence: 99%

“…Culham and Muzychka [18], and Khan et. al [19][20][21][22] extended that use in optimizing fully shrouded heat sinks.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Pin-Fin Heat Sinks in Bypass Flow Using Entropy Generation Minimization Method

Khan

Yovanovich

2007

ASME 2007 InterPACK Conference, Volume 1

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An entropy generation minimization, EGM, method is applied to study the thermodynamic losses caused by heat transfer and pressure drop for the fluid in a cylindrical pin-fin heat sink and bypass flow regions. A general expression for the entropy generation rate is obtained by considering control volumes around heat sink and bypass regions. The conservation equations for mass and energy with the entropy balance are applied in both regions. Inside the heat sink, analytical/empirical correlations are used for heat transfer coefficients and friction factors, where the reference velocity used in Reynolds number and pressure drop is based on the minimum free area available for the fluid flow. In bypass regions theoretical models, based on laws of conservation of mass, momentum and energy, are used to predict flow velocity and pressure drop. Both in-line and staggered arrangements are studied and their relative performance is compared for the same thermal and hydraulic conditions. A parametric study is also performed to show the effects of bypass on the overall performance of heat sinks.

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“…Khan et al [18] used entropy generation minimization to examine flow losses in a cross-flow heat exchanger with tube banks. The performance of both inline and staggered tube arrangements was reported.…”

Section: Introductionmentioning

confidence: 99%

Time varying NTU method for heat exchanger analysis with mass discharge

2011

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Transient operation of a co-current heat exchanger is analyzed in this paper, using a new predictive formulation for laminar and turbulent flows with mass discharge from the heat exchanger. The model includes time-varying mass discharge due to pressure regulated gas outflow. The temperature variations of the working fluid, heating fluid and the wall are predicted and validated against past data. It is found that the temperature of the working fluid rises sharply to a peak and then gradually decreases over time, due to mass discharge effects. The wall temperature decreases exponentially, and the temperature of the heating fluid falls sharply, and then gradually decreases. A benchmark case of a step change in the mass flow rate of the incoming fluid is analyzed and compared against past data for validation, after which results are presented and discussed for transient step changes of the incoming mass flow rate. List of symbolsA Heat transfer area (m 2 ) C p Specific heat (kJ/kg K) f, g Functions h Heat transfer coefficient (W/m 2 K) L Length of the heat exchanger (m) m Mass (kg) m Á Mass flow rate (kg/s) N Dimensionless parameter NTU Number of transfer units Nu Nusselt number P Pressure (kPa) Pe Perimeter (m) Pr Prandtl number Re Reynolds number T Temperature (°C or K) t Time (s) t cycle Total time of the heat exchanger operation (s) x Length of a heat exchanger section (m)Greek symbols c Ratio of final and initial mass flow rates q Density (kg/m 3 ) D Difference k 1,2 Roots of characteristic equations eHeat exchanger effectiveness Superscripts * Dimensionless form 0Initial condition at t = t 0 ? Condition at t = t ?

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Optimal Design of Tube Banks in Crossflow Using Entropy Generation Minimization Method

Cited by 10 publications

References 24 publications

Thermo-hydraulic study of a single row heat exchanger consisting of metal foam covered round tubes

Thermo-hydraulic study of a single row heat exchanger consisting of metal foam covered round tubes

Optimization of Pin-Fin Heat Sinks in Bypass Flow Using Entropy Generation Minimization Method

Time varying NTU method for heat exchanger analysis with mass discharge

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