scholarly journals Numerical study for heat transfer enhancement using CuO water nanofluids through mini-channel heat sinks for microprocessor cooling

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2965-2976 ◽  
Author(s):  
Muhammad Anwar ◽  
Hussain Tariq ◽  
Ahmad Shoukat ◽  
Hafiz Ali ◽  
Hassan Ali

Water cooled heat sinks are becoming popular due to increased heat generation inside the microprocessor. Timely heat removal from microprocessor is the key factor for better performance and long life. Heat transfer enhancement is reached either by increasing the surface area density and/or by altering the base fluid properties. Nanoparticles emerge as a strong candidate to increase the thermal conductivity of base fluids. In this research, the thermal performance of mini-channel heat sinks for different fin spacing (0.2 mm, 0.5 mm, 1 mm, and 1.5 mm) was investigated numerically using CuO-water nanofluids with volumetric concentration of 1.5%. The numerical values computed were than compared with the literature and a close agreement is achieved. We recorded the minimum base temperature of chip to be 36.8?C for 0.2 mm fin spacing heat sink. A reduction of 9.1% in base temperature was noticed using CuO-water nanofluids for 0.2 mm fin spacing as compared to previously experimental estimated value using water [1]. The drop percentage difference in pressure between water and CuO-water nanofluids was 2.2-13.1% for various fin spacing heat sinks. The percentage difference in thermal resistance between water and CuO-water nanofluids was computed 12.1% at maximum flow rate. We also observed uniform temperature distribution for all heat sinks.

Author(s):  
D. Sahray ◽  
R. Magril ◽  
V. Dubovsky ◽  
G. Ziskind ◽  
R. Letan

The present paper deals with horizontal-base pin fin heat sinks in free convection. The sinks have the same base dimensions and variable fin pitch. They are made of aluminum, and there is no contact resistance between the base and the fins. The fins have a constant square cross-section. The effect of fin pitch on the performance of the sink is studied experimentally and numerically. In the experiments, the heat sinks are heated using foil electrical heaters. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks are modeled using the Fluent 6 software. The results show that heat transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are analyzed. Also analyzed are the effects of the sink edges on the total heat transfer. A relative contribution of outer and inner fin rows in the sink is assessed, together with the effect of fin location in the array on the heat transfer rate from an individual fin. Dimensional analysis of the results is attempted, and a correlation presenting the Nusselt number vs. the Rayleigh number is suggested, where the inter-fin spacing serves as the characteristic length.


2013 ◽  
Vol 860-863 ◽  
pp. 649-655
Author(s):  
Wei Ping Hu ◽  
Wei Jun Liu ◽  
Cheng Long Xu

The paper presents a numerical simulation to investigate the heat transfer enhancement of a rectangular pipe with longitudinal fins for the automobile thermoelectric generator. The fins were inserted near the pipe wall. The effects of flow rate (wi=10m/s-50m/s), fin length ( l=100, 133, 200, 400), fin spacing (d=20, 30, 40, 50), fin height (h=20, 30, 40, 50) on Nusselt number (Nu), friction factor (f) and overall enhancement ratios (ƞ) are investigated under constant wall temperature , using air as woking fluid. Number calculations were performed with FLUENT code. The obtained results reveal that all geometric parameters have important effect on the thermal performance of pipe, and the finned pipe show better thermal performance than smooth pipe. It is also found that the overall enhancement ratios increase with increasing fin length and fin height, also the overall enhancement ratios decrease with increasing fin spacing. All finned pipes have good heat performance with ƞ greater than 1. The best overall enhancement of 1.25 was achieved for wi=10m/s for which the fin dimensions is l = 400mm, d = 20mm, h = 50mm.


Author(s):  
Michael Maurer ◽  
Jens von Wolfersdorf ◽  
Michael Gritsch

An experimental and numerical study was conducted to determine the thermal performance of V-shaped ribs in a rectangular channel with an aspect ratio of 2:1. Local heat transfer coefficients were measured using the steady state thermochromic liquid crystal technique. Periodic pressure losses were obtained with pressure taps along the smooth channel sidewall. Reynolds numbers from 95,000 to 500,000 were investigated with V-shaped ribs located on one side or on both sides of the test channel. The rib height-to-hydraulic diameter ratios (e/Dh) were 0.0625 and 0.02, and the rib pitch-to-height ratio (P/e) was 10. In addition, all test cases were investigated numerically. The commercial software FLUENT™ was used with a two-layer k-ε turbulence model. Numerically and experimentally obtained data were compared. It was determined that the heat transfer enhancement based on the heat transfer of a smooth wall levels off for Reynolds numbers over 200,000. The introduction of a second ribbed sidewall slightly increased the heat transfer enhancement whereas the pressure penalty was approximately doubled. Diminishing the rib height at high Reynolds numbers had the disadvantage of a slightly decreased heat transfer enhancement, but benefits in a significantly reduced pressure loss. At high Reynolds numbers small-scale ribs in a one-sided ribbed channel were shown to have the best thermal performance.


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