Development of new finned tube heat exchanger: Innovative tube-bank design and thermohydraulic performance

Lotfi, Babak; Sundén, Bengt

doi:10.1080/01457632.2019.1637112

Cited by 20 publications

(10 citation statements)

References 51 publications

(64 reference statements)

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“…Simulations of multiple streams in commercial CFD software can be performed only with the same set of governing equations, so in this investigation numerical simulations have been carried out using the Shear-Stress Transport (SST) k-ω turbulence model [26] for both air and water. Various studies of heat transfer and fluid flow in fin-and-tube heat exchangers [27][28][29][30] report that, even at low Reynolds numbers, results obtained using the SST k-ω turbulence model are in better agreement with experimental results in comparison with other available two-equations turbulence models.…”

Section: Governing Equationsmentioning

confidence: 90%

Heat Transfer Enhancement of Crossflow Air-to-Water Fin-and-Tube Heat Exchanger by Using Delta-Winglet Type Vortex Generators

2022

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The aim of this work is to numerically analyse fluid flow and heat transfer characteristics in a crossflow air-to-water fin-and-tube heat exchanger (FTHEX) by implementing two configurations of delta-winglet type vortex generators at the air side: delta-winglet upstream (DWU) and delta-winglet downstream (DWD). The vortex generators are mounted on a fin surface and deployed in a “common flow up” orientation. The effects of attack angles of 15°, 30° and 45° on air-side heat transfer and pressure drop were examined. Since the implementation of the full-size model would involve large numerical resources, the computational domain is simplified by considering a small segment in the direction of water flow. The fully developed temperature and velocity boundary conditions were set at the water inlets. To validate the defined mathematical model and numerical procedure, measurements have been performed on a plain FTHEX. The air side Reynolds number, based on hydraulic diameter, was in the range of 176 ≤ ReDh ≤ 400 and water side Reynolds number, based on inner tube diameter, was constant Redi = 17,065. The results have shown that the highest increase in the Colburn factor j (by 11–27%) and reduction in the air-side thermal resistance fraction (from 78.2–76.9% for ReDh = 176 to 76–72.4% for ReDh= 400) is achieved by using the DWD configuration with attack angle 45°. In addition, the overall heat transfer coefficient is improved by up to 15.7%. The DWD configuration with the attack angle 30° provides the greatest improvement in the heat transfer to pressure loss ratio, 5.2–15.4% over the range of ReDh studied.

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Section: Governing Equationsmentioning

confidence: 90%

Heat Transfer Enhancement of Crossflow Air-to-Water Fin-and-Tube Heat Exchanger by Using Delta-Winglet Type Vortex Generators

2022

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“…The hydraulic diameter approach is a simple dimensional parameter method to calculate the heat transfer and the pressure drop in the heat exchanger. The hydraulic diameter D h of the cold heat exchanger is defined [34]. The rate of entropy generation is represented as the dimensionless form N S [29]:…”

Section: The Quantityqmentioning

confidence: 99%

“…heat transfer and the pressure drop in the heat exchanger. The hydraulic diameter Dh of the cold heat exchanger is defined [34]. minimum flow area total volume frontal area total surface area…”

Section: The Quantityqmentioning

confidence: 99%

Second Law Analysis for the Experimental Performances of a Cold Heat Exchanger of a Stirling Refrigeration Machine

Djetel-Gothe

Lanzetta

Bégot

2020

Entropy

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The second law of thermodynamics is applied to evaluate the influence of entropy generation on the performances of a cold heat exchanger of an experimental Stirling refrigeration machine by means of three factors: the entropy generation rate N S , the irreversibility distribution ratio ϕ and the Bejan number B e | N S based on a dimensionless entropy ratio that we introduced. These factors are investigated as functions of characteristic dimensions of the heat exchanger (hydraulic diameter and length), coolant mass flow and cold gas temperature. We have demonstrated the role of these factors on the thermal and fluid friction irreversibilities. The conclusions are derived from the behavior of the entropy generation factors concerning the heat transfer and fluid friction characteristics of a double-pipe type heat exchanger crossed by a coolant liquid (55/45 by mass ethylene glycol/water mixture) in the temperature range 240 K < TC < 300 K. The mathematical model of entropy generation includes experimental measurements of pressures, temperatures and coolant mass flow, and the characteristic dimensions of the heat exchanger. A large characteristic length and small hydraulic diameter generate large entropy production, especially at a low mean temperature, because the high value of the coolant liquid viscosity increases the fluid frictions. The model and experiments showed the dominance of heat transfer over viscous friction in the cold heat exchanger and B e | N S → 1 and ϕ → 0 for mass flow rates m ˙ → 0.1 kg.s−1.

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“…In the wake region, recirculation zones typically appear with lower velocities and heat transfer rate. However, turbulent vortices improve the mixing and increase the heat transfer in the neighborhood regions too [26].…”

Section: Mesh Analysismentioning

confidence: 99%

Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits

Rogié

Markussen

Walther

et al. 2019

Fluids

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The present study investigated a new microchannel profile design encompassing condensate drainage slits for improved moisture removal with use of triangular shaped plain fins. Heat transfer and pressure drop correlations were developed using computational fluid dynamics (CFD) and defined in terms of Colburn j-factor and Fanning f-factor. The microchannels were square 2.00 × 2.00 mm and placed with 4.50 mm longitudinal tube pitch. The transverse tube pitch and the triangular fin pitch were varied from 9.00 to 21.00 mm and 2.50 to 10.00 mm, respectively. Frontal velocity ranged from 1.47 to 4.40 m·s −1 . The chosen evaporator geometry corresponds to evaporators for industrial refrigeration systems with long frosting periods. Furthermore, the CFD simulations covered the complete thermal entrance and developed regions, and made it possible to extract virtually infinite longitudinal heat transfer and pressure drop characteristics. The developed Colburn j-factor and Fanning f-factor correlations are able to predict the numerical results with 3.41% and 3.95% deviation, respectively.

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Development of new finned tube heat exchanger: Innovative tube-bank design and thermohydraulic performance

Cited by 20 publications

References 51 publications

Heat Transfer Enhancement of Crossflow Air-to-Water Fin-and-Tube Heat Exchanger by Using Delta-Winglet Type Vortex Generators

Heat Transfer Enhancement of Crossflow Air-to-Water Fin-and-Tube Heat Exchanger by Using Delta-Winglet Type Vortex Generators

Second Law Analysis for the Experimental Performances of a Cold Heat Exchanger of a Stirling Refrigeration Machine

Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits

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