Effect of the leakage on pressure drop and local heat transfer in shell-and-tube heat exchangers for staggered tube arrangement

The objective of this study was to investigate, through experiments, the combined effects of a sharp 180 deg turn and rib patterns on the pressure drop performance and distributions of the local heat transfer coefficient in an entire two-pass rib-roughened channel with a 180 deg turn. The rib pitch-to-equivalent diameter ratio P/de was 1.0, the rib-height-to-equivalent diameter ratio e/de was 0.09, and the rib angle relative to the main flow direction was varied from 30 ∼ 90 deg with an interval of 15 deg. Experiments were conducted for Reynolds numbers in the range 4000 ∼ 30,000. It was disclosed that, due to the interactions between the bend-induced secondary flow and the rib-induced secondary flow, the combination of rib patterns in the channel before and after the turn causes considerable differences in the pressure drop and heat transfer performance of the entire channel.

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Optimization of heat transfer in shell-and-tube heat exchangers using MOGA algorithm: adding nanofluid and changing the tube arrangement

Chemical Engineering Communications ◽

10.1080/00986445.2021.1983548 ◽

2021 ◽

pp. 1-15

Author(s):

Yacine Khetib ◽

Hala M. Abo-Dief ◽

Abdullah K. Alanazi ◽

S. Mohammad Sajadi ◽

Suvanjan Bhattacharyya ◽

...

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Tube Arrangement ◽

Shell And Tube

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Comparison of Pressure Drop and Endwall Heat Transfer Measurements to Flow Visualization Testing of Solid and Porous Pin Fin Arrays

Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C ◽

10.1115/imece2009-10271 ◽

2009 ◽

Cited By ~ 1

Author(s):

Jared M. Pent ◽

Jay S. Kapat ◽

Mark Ricklick

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Flow Visualization ◽

Local Heat Transfer ◽

Ccd Camera ◽

Local Heat ◽

Transfer Coefficients ◽

Porous Aluminum ◽

Pin Fins ◽

A Charge

This paper examines the local and averaged endwall heat transfer effects of a staggered array of porous aluminum pin fins with a channel blockage ratio (blocked channel area divided by open channel area) of 50%. Two sets of pins were used with pore densities of 0 (solid) and 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates using each set of pins. Local heat transfer coefficients on the endwall were measured using Thermochromatic Liquid Crystal (TLC) sheets recorded with a charge-coupled device (CCD) camera. Static and total pressure measurements were taken at the entrance and exit of the test section to determine the overall pressure drop through the channel and explain the heat transfer trends through the channel. The heat transfer and pressure data was then compared to flow visualization tests that were run using a fog generator. Results are presented for the two sets of pins with Reynolds numbers between 25000 and 130000. Local HTC (heat transfer coefficient) profiles as well as spanwise and streamwise averaged HTC plots are displayed for both pin arrays. The thermal performance was calculated for each pin set and Reynolds number. All experiments were carried out in a channel with an X/D of 1.72, a Y/D of 2.0, and a Z/D of 1.72.

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Numerical Flow Simulation of Spacer Grids With Mixing Vanes in a 5 × 5 PWR Rod Bundle

Volume 5: Fuel Cycle and High and Low Level Waste Management and Decommissioning; Computational Fluid Dynamics (CFD), Neutronics Methods and Coupled Codes; Instrumentation and Control ◽

10.1115/icone17-75354 ◽

2009 ◽

Cited By ~ 1

Author(s):

Moyse´s Alberto Navarro ◽

Andre´ Augusto Campagnole dos Santos

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Pressure Loss ◽

Considerable Increase ◽

Local Heat Transfer ◽

Local Heat ◽

Spacer Grid ◽

Spacer Grids ◽

Rod Bundle ◽

Vane Angle

The spacer grids exert great influence on the thermal hydraulic performance of the PWR fuel assembly. The presence of the spacers has two antagonistic effects on the core: an increase of pressure drop due to constriction on the coolant flow area and increase of the local heat transfer downstream the grids caused by enhanced coolant mixing. The mixing vanes, present in most of the spacer grid designs, cause a cross and swirl flow between and in the subchannels, enhancing even more the local heat transfer at the cost of more pressure loss. Due to this important hydrodynamic feature the spacer grids are often improved aiming to obtain an optimal commitment between pressure drop and enhanced heat transfer. In the present work, the fluid dynamic performance downstream a 5 × 5 rod bundle with spacer grids is analyzed with a commercial CFD code (CFX 11.0). Eleven different split vane spacer grids with angles from 16° to 36° and a spacer without vanes were evaluated. The computational domain extends from ∼10 Dh upstream to ∼50 Dh downstream the spacer grids. The standard k-ε turbulence model with scalable wall functions and the total energy model were used in the simulations. The results show a considerable increase of the average Nusselt number and secondary mixing with the angle of the vane up to ∼20 Dh downstream the spacer, reducing greatly the influence of the vane angle beyond this region. As expected, the pressure loss through the spacer grid also showed considerable increase with the vane angle.

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