Evolutionary Design of Novel Coolant Passages for Cooling a Square Substrate by Single Stream

2021 ◽  
Author(s):  
Ajit Kumar Sahoo ◽  
Ashok Kumar Barik ◽  
Prafulla Kumar Swain
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Dimensionless Temperature ◽  
Pipe Length ◽  
Rapid Fall ◽  
Uniform Wall ◽  
Temperature And Pressure ◽  
Single Pipe ◽  
Uniform Wall Heat Flux ◽  
Fluid Characteristics

Abstract Different designs of novel coolant (i.e., water) circuits have been proposed using a well-established constructal law to cool a square substrate made up of aluminum oxide, and subjected to a uniform wall heat flux. Five different flow-path topologies: Case-1 (umbrella-shaped), Case-2 (dumbbell-shaped), Case-3 (hexagonal-shaped), Case-4 (down-arrow-shaped), and Case-5 (up-arrow-shaped) are evolved from a single pipe embedded in the heated substrate. The best cooling pathway has been anticipated by comparing the thermo-fluid characteristics of designs. A numerical route, via Ansys R 16, has been implemented to solve the transport equations for continuity, momentum, and energy along with relevant boundary conditions. The non-dimensional temperature and pressure drop for these cases have been quantified and compared, by varying the length and Reynolds number in the range of 2-3, and 100-2,000, respectively. We observe a decrease in the dimensionless temperature and an increase in the pressure drop with Reynolds number for all the considered pathways. At Re<=500, a rapid fall in the non-dimensional temperature has been noticed; and thereafter, it looks like a plateau for all cases. For Case-4, a minimum temperature is obtained at the non-dimensional pipe length of 2.5. At Lc/L=2.5, we observe that the Case-4 provides better cooling to the substrate among all other designs. Also, the pressure drop for case 4 is not too high as compared to other designs.

Effects of transversely twisted-turbulators on heat transfer and pressure drop of a channel with uniform wall heat flux

2020 ◽  
Vol 154 ◽  
pp. 108027
Author(s):  
Ashkan Alimoradi ◽  
M. Fatahi ◽  
Shafiqur Rehman ◽  
Morteza Khoshvaght-Aliabadi ◽  
S.M. Hassani
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Wall Heat Flux ◽  
Uniform Wall ◽  
Uniform Wall Heat Flux

Simultaneous Heat Transfer and Pressure Drop Measurements for a Horizontal Micro-Tube

2011 ◽  
Author(s):  
Lap Mou Tam ◽  
Hou Kuan Tam ◽  
Afshin J. Ghajar
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Pressure Drop ◽  
Heating Condition ◽  
Flux Boundary Condition ◽  
Number Range ◽  
Uniform Wall ◽  
Heat Flux Boundary Condition ◽  
Uniform Wall Heat Flux

Heat transfer and pressure drop measurements for horizontal macro-tubes under uniform wall heat flux boundary condition have been conducted by various researchers in recent years. From their studies, it was shown that good agreements were observed in the laminar and turbulent regions. However, for the transition region, the heat transfer and pressure drop characteristics depended on various factors, such as inlet configuration, buoyancy effect, and surface roughness. In a recent study by Tam et al. (2010), they measured the heat transfer and pressure drop simultaneously for a horizontal macro-tube with and without internally micro-fins and concluded that under the heating condition, the transition Reynolds number range for heat transfer and pressure drop were completely different. The transition Reynolds number range was documented in their research in great detail. However, for horizontal micro-tubes, there is no information in the literature on the simultaneous behavior of the heat transfer and pressure drop, especially in the transition region. In order to fill in this gap, an experimental setup was built to measure the heat transfer and pressure drop simultaneously for a horizontal micro-tube under uniform wall heat flux boundary condition. Water was used as the test fluid and the test section was a stainless steel micro-tube with 1000μm diameter. For heat transfer, the results indicated that the micro-tube had an earlier start and end of transition compared to the macro-tube and, in the turbulent region, an increase in heat transfer due to the surface roughness was observed. For friction factor under isothermal condition, the micro-tube had a narrower transition range due to the roughness compared to the macro-tube. For friction factor under heating condition, the laminar data and the start of transition were different from the isothermal case, and the effect of heating was not seen on the end of transition.

scholarly journals Parametric optimization of a stamped longitudinal vortex generator inside a circular tube of a solar water heater at low Reynolds numbers

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
Felipe A. S. Silva ◽  
Luis Júnior ◽  
José Silva ◽  
Sandilya Kambampati ◽  
Leandro Salviano
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Reynolds Numbers ◽  
Geometric Parameters ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

AbstractSolar Water Heater (SWH) has low efficiency and the performance of this type of device needs to be improved to provide useful and ecological sources of energy. The passive techniques of augmentation heat transfer are an effective strategy to increase the convective heat transfer coefficient without external equipment. In this way, recent investigations have been done to study the potential applications of different inserts including wire coils, vortex generators, and twisted tapes for several solar thermal applications. However, few researchers have investigated inserts in SWH which is useful in many sectors where the working fluid operates at moderate temperatures. The longitudinal vortex generators (LVG) have been applied to promote heat transfer enhancement with a low/moderate pressure drop penalty. Therefore, the present work investigated optimal geometric parameters of LVG to enhance the heat transfer for a SWH at low Reynolds number and laminar flow, using a 3D periodical numerical simulation based on the Finite Volume Method coupled to the Genetic Algorithm optimization method (NSGA-II). The LVG was stamped over a flat plate inserted inside a smooth tube operating under a typical residential application corresponding to Reynolds numbers of 300, 600, and 900. The geometric parameters of LGV were submitted to the optimization procedure which can find traditional LVG such as rectangular-winglet and delta-winglet or a mix of them. The results showed that the application of LGVs to enhance heat transfer is an effective passive technique. The different optimal shapes of the LVG for all Reynolds numbers evaluated improved more than 50% of heat transfer. The highest augmentation heat transfer of 62% is found for the Reynolds number 900. However, the best thermo-hydraulic efficiency value is found for the Reynolds number of 600 in which the heat transfer intensification represents 55% of the pressure drop penalty.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

Monitoring of the fluidized bed particle drying process by temperature and pressure drop measurements

2021 ◽  
pp. 1-13
Author(s):  
Gabriela Saldanha Soares ◽  
Scarlet Neves Tuchtenhagen ◽  
Luiz Antonio de Almeida Pinto ◽  
Carlos Alberto Severo Felipe
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Drying Process ◽  
Temperature And Pressure

scholarly journals Simulation approach on turbulent thermal performance factor of Al2O3-Cu/water hybrid nanofluid in circular and non-circular ducts

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ing Jiat Kendrick Wong ◽  
Ngieng Tze Angnes Tiong
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Hybrid Nanofluid ◽  
Performance Factor ◽  
Thermal Performance Factor ◽  
The Heat Transfer Coefficient

AbstractThis paper presents the numerical study of thermal performance factor of Al2O3-Cu/water hybrid nanofluid in circular and non-circular ducts (square and rectangular). Turbulent regime is studied with the Reynolds number ranges from 10000 to 100000. The heat transfer performance and flow behaviour of hybrid nanofluid are investigated, considering the nanofluid volume concentration between 0.1 and 2%. The thermal performance factor of hybrid nanofluid is evaluated in terms of performance evaluation criteria (PEC). This present numerical results are successfully validated with the data from the literature. The results indicate that the heat transfer coefficient and Nusselt number of Al2O3-Cu/water hybrid nanofluid are higher than those of Al2O3/water nanofluid and pure water. However, this heat transfer enhancement is achieved at the expense of an increased pressure drop. The heat transfer coefficient of 2% hybrid nanofluid is approximately 58.6% larger than the value of pure water at the Reynolds number of 10000. For the same concentration and Reynolds number, the pressure drop of hybrid nanofluid is 4.79 times higher than the pressure drop of water. The heat transfer performance is the best in the circular pipe compared to the non-circular ducts, but its pressure drop increment is also the largest. The hybrid nanofluid helps to improve the problem of low heat transfer characteristic in the non-circular ducts. In overall, the hybrid nanofluid flow in circular and non-circular ducts are reported to possess better thermal performance factor than that of water. The maximum attainable PEC is obtained by 2% hybrid nanofluid in the square duct at the Reynolds Number of 60000. This study can help to determine which geometry is efficient for the heat transfer application of hybrid nanofluid.

Numerical and Experimental Analysis of Turbulent Flow in Corrugated Pipes

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Henrique Stel ◽  
Rigoberto E. M. Morales ◽  
Admilson T. Franco ◽  
Silvio L. M. Junqueira ◽  
Raul H. Erthal ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Velocity Magnitude ◽  
Geometric Configurations ◽  
Corrugated Surfaces ◽  
Friction Factors

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

Enhancement of Heat Transfer of Rectangular Saw Tooth Shaped Micro Channel Heat Sink with Water Nano Fluid/Aluminium Oxide

2015 ◽  
Vol 813-814 ◽  
pp. 685-689
Author(s):  
M. Vijay Anand Marimuthu ◽  
B. Venkatraman ◽  
S. Kandhasamy
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Heat Sink ◽  
Micro Channel ◽  
Performance Curve ◽  
Theoretical Level ◽  
Enhancement Of Heat Transfer ◽  
Nano Fluid

This paper investigates the performance and characteristics of saw tooth shape micro channel in the theoretical level. If the conduct area of the nano fluid increases the heat transfer also increases. The performance curve has drawn Reynolds number against nusselt number, heat transfer co efficient. Pressure drop plays an important role in this device. If pressure drop is high the heat transfer increases. The result in this experiment shows clearly that the heat transfer is optimized.

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