To amplify the rate of heat transfer and thermal performance the powerful tool is used in the enhancement of heat transfer. The urge to increase the heat transfer rate is found more in electronic components/devices as the working of the components/device at designed efficiency is required. This in turn leads to the invention of a greater number of different types of heat sinks and out of which the performances of few works are as stated- that the average heat transfer coefficient, heat transfer rate increase with the reduction of weight in discrete fins and perforated fins compared to the solid fins block. The Nusselt number rises with an increase in heat input for all types

Experimental Setup consists of mild steel Tube table which has top frame cover and panel which consists of Digital Ammeter, Voltmeter, Blower, Flow control valve, Heater control, Manometer, Selector Knob, and gate valve. The test duct is chosen with the dimension of 70mm*100mm*190mm. Air is the fluid used for convection and the type of flow chosen is turbulence. Further the entrance ledge is not considered into account.

The heat sinks are made from brass with a heater. Along with the brass plate, there is a bottom insulation plate. The extended surfaces with a perforated design which is similar to the honeycomb structure has six thermocouples placed on it.

The location of the first two thermocouples is on the base source plate, the next two thermocouples are on the extended fins, the fifth thermocouple is at the air inlet point and the sixth thermocouple at the air exit point.

Three different shaped heat sinks made up of brass material is tested in the test rig as shown in Figure A for knowing its heat dissipation capacity. Each sample plate has dimensions of 38mm width, 68mm length and 1mm thickness. For Forced condition, the blower is kept in ON condition, set manometer by adjusting the valve slowly as the mains gets switched ON, the heater control knob is rotated to set the required voltage, after reaching steady-state readings of voltage, current and all temperatures are noted. The experiment is repeated for different heat inputs.

The heat transfer coefficient is calculated using the Newton’s law of cooling i.e.

Where h is heat transfer coefficient in W/m^{2o}C

A is the area of heat transfer surface in m^{2}

Q is the rate of heat transfer in W

dT is the Temperature difference between the surface and the surroundings.

The Nusselt number is calculated using

Where Nu is Nusselt number

Re is Reynolds number

Pr is Prandtl number

Pr_{f} is Prandtl number at film temperature

Pr_{w} is Prandtl number at wall temperature.

The values of C and m are chosen based on Reynolds number and value of n is based on Prandtl number.

Voltage(A) |
Shape of Heat sink (B) |
Heat transfer coefficient |
Nusselt number |
Thermal resistance |
SNRA1 |
SNRA2 |
SNRA3 |

80 |
Honey Comb |
27.33 |
100.56 |
0.5664 |
28.7328 |
40.0485 |
4.93754 |

80 |
Radial |
22.02 |
91.32 |
0.7031 |
26.8563 |
39.2113 |
3.05966 |

80 |
Flared |
24.77 |
91.77 |
0.6250 |
27.8785 |
39.2540 |
4.08240 |

100 |
Honey Comb |
27.19 |
98.27 |
0.5693 |
28.6882 |
39.8484 |
4.89318 |

100 |
Radial |
21.73 |
88.74 |
0.7125 |
26.7412 |
38.9624 |
2.94430 |

100 |
Flared |
21.01 |
89.53 |
0.7368 |
26.4485 |
39.0394 |
2.65301 |

120 |
Honey Comb |
21.12 |
97.01 |
0.5903 |
26.4939 |
39.7363 |
4.57854 |

120 |
Radial |
20.35 |
86.34 |
0.7609 |
26.1713 |
38.7242 |
2.37345 |

120 |
Flared |
19.20 |
87.67 |
0.8062 |
25.6660 |
38.8570 |
1.87114 |

Table1.indicates L9 orthogonal array which is designed for the optimization of different parameters like coefficient of heat transfer, Nusselt number and thermal resistance.

Heat Transfer Coefficient |
Nusselt Number |
Thermal Resistance |
||||||

Level |
A |
B |
Level |
A |
B |
Level |
A |
B |

1 |
27.82 |
27.97 |
1 |
39.50 |
39.88 |
1 |
4.027 |
4.803 |

2 |
27.29 |
26.59 |
2 |
39.28 |
38.97 |
2 |
3.497 |
2.792 |

3 |
26.11 |
26.66 |
3 |
39.11 |
39.07 |
3 |
2.941 |
2.869 |

Delta |
1.71 |
1.38 |
Delta |
0.40 |
0.91 |
Delta |
1.085 |
2.011 |

Rank |
1 |
2 |
Rank |
2 |
1 |
Rank |
2 |
1 |

Table 2. indicates the analysis for coefficient of heat transfer, Nusselt number and thermal resistance for optimization using Taguchi method. From this analysis it is clear that voltage input parameter is more important for heat transfer coefficient. Where as in case of Nusselt number and Thermal resistance shape of heat sink is more important parameter compared to voltage Input.

Sl.No |
Authors |
Title of the work |
Study/ Description |
Observations |

1. |
Alhassan Salami Tijania, Nursyameera Binti Jaffria |
Thermal analysis of perforated pin-fins heat sink under forced convection condition |
This research experimentation aims at studying the effect of perforated pin fins on heat sinks thermal performance under forced convection. Results of perforated pin fins and flat plate heat sink is compared to solid pin fins and solid flat plate heat sink. |
In this study, the experimental analysis shows that with the increase in Reynolds number, increases the Nusselt number and heat transfer coefficient. Figure 13 and 14 from the experimental analysis exhibits the same trend. |

2. |
Nabeel Abdulhadi Ghyadh, Sahib Shihab Ahmed, Maher A.R. Sadiq Al-Baghdadi |
Enhancement of Forced Convection Heat Transfer from Cylindrical Perforated Fins Heat Sink-CFD Study |
Three-dimensional, non-isothermal CFD model is studied to notice the thermal performance of heat sink having perforated fins. The arrangement of fins is also studied. Results obtained from CFD are compared with available experimental results. |
In this study, CFD analysis shows that the Nusselt number and thermal transmittance increases with increase in Reynolds number for all the samples. Figure 1 and 14 from the experimental analysis exhibits the same trend. |

3. |
Emad M.S. El-Said , Gamal B. Abdelaziz , Swellam W. Sharshir , Ammar H. Elsheikh, Ashraf Mimi Elsaid |
Experimental investigation of the twist angle effects on thermo-hydraulic performance of a square and hexagonal pin fin array in forced convection |
Experimentations were conducted on two pin fin section on a square and hexagonal shaped with four twist angles of 0o, 30o, 60o, and 90o with air as working medium at constant heat flux and Reynolds number (Re) ranging from 3182 to 9971. The thermo-hydraulic performance of the heat sink under forced convection at various operating conditions and design factors are found. |
From this experimental investigation of pin fin array under forced convection, it is observed that the increase in Reynolds number increases the Nusselt number and decreases the thermal resistance. Figure 5 and 14 from the experimental analysis exhibits the same trend. |

4. |
Ayush Gupta, Vishwjeet Choudhary, Varun Singh, Rahul Chamola |
Heat Transfer Characteristics through Plate-Pin Heat Sink with Dimples |
Plate fins having dimples are placed in between the pin fins. Experimental investigation is carried out under forced convection by varying pin-pitch ratio and plate-pitch ratio. The experiment is carried out at constant heat flux and by varying the Reynolds number from 6500 to 15000. |
The trend of increase in Nusselt number and decrease in friction factor are observed with the increase in Reynolds number for all the samples. Figure 14 from the experimental analysis exhibits the same trend. |

5. |
Osot Khonsue |
Enhancement of the forced convective heat transfer on mini pin fin heat sinks with micro spiral fins |
Experimental investigation on aluminium pin fins of rectangular, cylindrical and spiral shaped using air as working medium under constant heat flux and by varying Reynolds number from 322 to 1982. This experimental study is done to find the characteristics of heat transfer and pressure drop-in mini heat sinks. |
The average heat transfer coefficient and Nusselt number increases with increase in Reynolds number for all the variations of rectangular, cylindrical and Spiral pin fins. Figure 13 and 14 from the experimental analysis exhibits the same trend. |

6. |
Ambarish Maji, Dipankar Bhanja, Promod Kumar Patowari, and BalaramKundu |
Thermal Analysis for Heat Transfer Enhancement in Perforated Pin Fins of Various Shapes with Staggered Arrays |
This work finds the heat dissipation through staggered different shaped pin fins with varying perforated geometries. To examine the effects on the fin geometry and perforated dimension along the shape of fin, 3 dimensional CFD simulation has been carried out. Also, enhancement of heat transfer rate against pressure loss is studied. |
Fin geometry of perforated fin influences the pressure drop. It is also noted that Nusselt number, Heat transfer and pressure drop grows with the rise in Reynolds number. Figure 6,13 and 14 from the experimental analysis exhibits the same trend. |

Table 3. compares the previous related works. Heat sinks with different shapes and by varying conditions are studied through different methods like experimentation, CFD analysis to find the enhancement of heat transfer. From the studies it is observed that the coefficient of heat transfer and Nusselt number grows with the rise in Reynolds number for most of all the samples.

From Figure. 8 and 3, it is clear that the Reynolds number and the coefficient of heat transfer decreases with the increase in voltage input. From this it is clear that the heat transfer coefficient and Nusselt number grows with rise in Reynolds number.

The results obtained from the experiment are inline when compared with the literature survey results obtained by analytical and numerical methods. The above results are obtained from the actual experimentation. This experiment has led the way to find different parameters like coefficient of heat transfer, Nusselt number, Reynolds number, pressure drop and effectiveness of fins. Further the results of this work can be compared with the results obtained from either analytical or numerical method.

Experimentation and Taguchi analysis shows that the Honey comb shaped heat sink is better to enhance heat transfer in electronic devices compared to radial and flared heat sink as the heat transfer coefficient of honey comb shaped heat sink for 100V of voltage input is more by 20.01% and 22.73%, also shows higher Nusselt number by 9.7% and 8.9% along with decrease in thermal resistance by 20.1% and 22.73% with respect to radial and flared heat sinks respectively. Designing of new heat sink to reduce the pressure drop and thermal resistance can be considered as a suggestion for future studies. Studies can also be extended by varying the fin design parameters like number of fins, fin spacing and thickness of fins. This experimental study manifest that the heat dissipation is more in honey comb shaped heat sink when compared with radial and flared heat sink.