Study of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection

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.

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
G. Ziskind ◽  
R. Letan

This paper aims at deeper understanding of heat transfer from horizontal-base pin-fin heat sinks with exposed edges in free convection of air. The effects of fin height and fin population density are studied experimentally and numerically. The sinks are made of aluminum, and there is no contact resistance between the base and the fins. All the sinks studied have the same base dimensions and are heated using foil electrical heaters. The fins have a constant square cross section, whereas the fin height and pitch vary. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks and their environment are modeled using the FLUENT 6.3 software. The results show that heat-transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are assessed quantitatively and analyzed for various fin heights. Also analyzed is the heat flux distribution at the edges and center of the sink. 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. By decoupling convection from radiation, a dimensional analysis of the results for natural convection is attempted. A correlation presenting the Nusselt number versus the Rayleigh number is suggested, where the “clear” spacing between fins serves as the characteristic length.


2010 ◽  
Vol 132 (11) ◽  
Author(s):  
D. Sahray ◽  
G. Ziskind ◽  
R. Letan

This paper provides further insight in heat transfer from horizontal-base pin fin heat-sinks in free convection of air. The main objective is to assess the effect of base size, and this with regard to the effects of fin height and fin population density studied in a previous work (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13). To this end, experimental and numerical investigations are performed with sinks of different base sizes. The sinks are made of aluminum, with no contact resistance between the base and the fins, and are heated using foil electrical heaters. In the corresponding numerical study, the sinks and their environment are modeled using the FLUENT 6.3 software. In the experiments, sink bases of 100×100 mm2 and 200×200 mm2 are used, while in the numerical study sinks of 50×50 mm2 are investigated, too. In addition to the sinks with exposed, free edges (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13), the same sinks are explored also with their edges blocked. This is done in order to exclude the edge effect, thus making it possible to estimate heat transfer from a sink of an “infinite” base size. Heat-transfer enhancement due to the fins is assessed quantitatively and analyzed for various base sizes and fin heights. The effect of fin location in the array on its contribution to the heat-transfer rate from the sink is analyzed. By decoupling convection from radiation, a dimensional analysis of the results for natural convection is attempted. Interdependence of the base size and fin height effects on the heat transfer is demonstrated. A correlation that encompasses all the cases studied herein is obtained, in which the Nusselt number depends on the Rayleigh number, which uses the “clear” spacing between fins as the characteristic length, and on the dimensions of the fins and the base.


Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. For the same base dimensions the fin height and pitch vary. The fins have a constant square cross-section. The edges of the sink are blocked: the surrounding insulation is flush with the fin tips. The effect of fin height and 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 and their environment 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 for various fin heights. Also assessed are effects of the blocked edges as compared to the previously studied cases where the sink edges were exposed to the surroundings.


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 ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. The sinks have the same base dimensions whereas the fin height and pitch vary. The fins have a constant square cross-section. The effect of fin height and 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 and their environment are modeled using the Fluent 6.3 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 for various fin heights.


2013 ◽  
Vol 479-480 ◽  
pp. 274-278
Author(s):  
Tzer Ming Jeng ◽  
Sheng Chung Tzeng ◽  
Chi Huang Liu ◽  
Yu Xiang Huang

This work experimentally investigated the effect of the oscillation move on the heat transfer enhancement of the pin-fin heat sinks with circular impinging jets. The forced convective cooling system usually applies the steady flow to pass through a stationary object. This work mounted the pin-fin heat sinks onto an oscillating platform with the impinging air jets. The experimental results indicate that strokes of the platform moving up and down as well as left and right are too long to enhance the overall heat transfer of the pin-fin heat sinks.


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