Numerical Study of Heat Transfer and Pressure Drop of Integral Pin-Fin Tubes

Author(s):  
Shuai Shi ◽  
Chang-qi Yan ◽  
Guang-lin Niu
Author(s):  
Jian Yang ◽  
Min Zeng ◽  
Qiuwang Wang

Pin fin heat exchanges are often used in cooling of high thermal loaded electronic components due to their excellent heat transfer performance. However, the pressure drop in such heat exchanges is usually much higher than that in others, so their overall heat transfer performance is seriously reduced. In order to reduce the pressure drop and improve the overall heat transfer performance for pin fin heat exchangers, porous metal pin arrays are used and the performance of fluid flow and heat transfer in heat exchanger unit cells are numerically studied. The Forchheimer-Brinkman extended Darcy model and two-equation heat transfer model for porous media are employed and the effects of Reynolds number (Re), permeability (K) and pin fin cross-section forms are studied in detail. The results show that, with proper selection of governing parameters, the overall heat transfer performance of porous pin fin heat exchanger is much better than that of traditional solid pin fin heat exchanger; the overall heat transfer performance of long elliptic porous pin fin heat exchanger is the best, that is, the heat transfer per unit pressure drop of such heat exchanger is the highest and the maximum value of the heat transfer over pressure drop is obtained at K = 2×10−7 m2.


Author(s):  
N. Kulasekharan ◽  
B. V. S. S. S. Prasad

A numerical investigation is carried out for estimating the influence of rib turbulators on heat transfer and pressure drop of staggered non-uniform pin-fin arrays of different shapes, in a simulated cambered vane trailing region. Pin-fins of square, circular and the diamond shapes, each of two sizes (d) were chosen. The ratio of span-wise pitch to longitudinal pitch is 1.06 and that to the pin size are 4.25 and 3.03, for all pin shapes. A constant heat flux boundary condition is assumed over the coolant channel walls, rib surfaces and circumferential faces of the pin-fins. Reynolds number is varied (20,000<ReD<40,000) by changing the coolant outlet to inlet pressure ratio. Pin end-wall and pin surface averaged heat transfer coefficients and Nusselt numbers are estimated and detailed contours of heat transfer coefficient on both the pressure and suction surfaces are presented. Whilst there is an enhancement in heat transfer and pressure drop with ribs for all the pin shapes, diamond pins have shown the highest enhancement values for both ribbed and non-ribbed configuration.


Author(s):  
Lv Ye ◽  
Zhao Liu ◽  
Chun Gao ◽  
Xing Yang ◽  
Zhenping Feng

This paper numerically investigated the flow and heat transfer characteristics in a rectangular channel with pin-fin arrays. The channel simulates a wide aspect ratio (W/E = 3) internal cooling passage of gas turbine blade. The pin-fin applied in the simulation is a new-proposed geometry which consists of a cylinder body with a fixed ratio of diameter to channel height, D0/E = 1/4, and a rounded tip. Each case corresponds to a specific pin-fin array geometry of detachment spacing C between the pin-tip and endwall. In the rig studied, 18 rows of pin-fins are in staggered arrangement along the streamwise direction. The investigation on pin-fin performance has been made mainly into two aspects. One is the effect of diameter of the rounded tip Dh on heat transfer performance and pressure loss in the system, while the other is the effect of detachment C. All the cases have been performed with the range of the Reynolds numbers from 15,000 to 25,000. The SST k–w turbulence model is employed for all the computational analysis. Results reveal that the presence of rounded-tip pin-fin with a detachment effectively promotes the wall-flow interactions and enhances heat transfer on endwalls. The rounded tip diameter has a slight effect on heat transfer and pressure drop in the channel. In the study range, relatively higher detachment promotes higher heat transfer coefficient. In general, the new-proposed pin-fin geometry induces greater heat transfer enhancement and yields relatively lower pressure drop.


Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4417
Author(s):  
Tingting Xu ◽  
Hongxia Zhao ◽  
Miao Wang ◽  
Jianhui Qi

Printed circuit heat exchangers (PCHEs) have the characteristics of high temperature and high pressure resistance, as well as compact structure, so they are widely used in the supercritical carbon dioxide (S-CO2) Brayton cycle. In order to fully study the heat transfer process of the Z-type PCHE, a numerical model of traditional Z-type PCHE was established and the accuracy of the model was verified. On this basis, a new type of spiral PCHE (S-ZPCHE) is proposed in this paper. The segmental design method was used to compare the pressure changes under 5 different spiral angles, and it was found that increasing the spiral angle θ of the spiral structure will reduce the pressure drop of the fluid. The effects of different spiral angles on the thermal-hydraulic performance of S-ZPCHE were compared. The results show that the pressure loss of fluid is greatly reduced, while the heat transfer performance is slightly reduced, and it was concluded that the spiral angle of 20° is optimal. The local fluid flow states of the original structure and the optimal structure were compared to analyze the reason for the pressure drop reduction effect of the optimal structure. Finally, the performance of the optimal structure was analyzed under variable working conditions. The results show that the effect of reducing pressure loss of the new S-ZPCHE is more obvious in the low Reynolds number region.


2021 ◽  
Vol 170 ◽  
pp. 107109
Author(s):  
Mohanad A. Alfellag ◽  
Hamdi E. Ahmed ◽  
Mohammed Gh. Jehad ◽  
Marwan Hameed

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