**3. Effective parameters on the efficiency of heat sinks**

The thermal/hydraulic performance of the heat sink is affected by geometrical parameters (such as the shape of the cross-section, pattern, inlet/outlet arrangement) and flow parameters (such as working fluids and boiling flow) [35]. In this section, the effective parameters on the heat sink's thermal–hydraulic performance are presented.

#### **3.1 Geometrical parameters**

#### *3.1.1 Patterns*

first time. Several parameters have also been considered to improve microchannel heat sinks efficiency, such as changing the cross-sections, patterns, manifolds, and

metrical parameters and fluid flow structures in a microchannel.

of heat sink research are presented.

**2. Microchannel and micro pin-fin heat sinks**

the channel dimensions shown in **Table 1**.

**Table 1.**

**156**

*Channel classification [8].*

Some technical issues have been reported, like generating hotspots and pressure drop through the microchannel for different applications. For instance, Copeland et al. [5] illustrated the impact of pressure drop and temperature gradient on system functionality. Moreover, they reported high-pressure drops (2 bars) for reaching minimal thermal resistance due to the small size of channels. Although utilizing a pump could compensate, the generated pressure drop which is used in conventional applications, using these pumps on a micro-scale is almost impossible [6]. The thermal boundary layer in convectional channels is maintained in a fully-developed state; thus, the thermal resistance increases and caused non-uniform heat transfer performance, leading to an unreliable platform and system failure. A large number of researches have been carried out to address these limitations by changing geo-

In the current study, all previously reported parameters relating to enhancing the heat sink efficiency are considered. The efficient parameters on the performance of micro heat sinks are divided into two main parts, i.e., (i) Geometrical and (ii) Flow parameters. Geometrical parameters include patterns, cross-sections, and

The difference between macro-, mini-, and microchannels remains a lack of complete definition. However, it is fair to say that these differences can be classified into two groups; phenomenology and dimensions. Forces and phenomena play an essential role in micro-scale rather than macro-, mini scales [7]. Channel classification is based on hydraulic diameter as a simple guide to examine the desired dimensional range. Kandlikar and Grande [8] presented a general scheme based on

In **Table 1**, D is the hydraulic diameter of the channel. In non-circular channels,

it is recommended to use the smallest channel dimension in place of hydraulic diameter (e.g., the short side of a rectangular cross-section) [8]. Also, multiple microfluidic fabrication techniques have been developed, such as photolithography

Macrochannels **D > 3mm** Minichannels **3mm ≥ D ≥ 200 μm** Microchannels **200 μm ≥ D ≥ 10 μm** Transitional microchannels **10 μm ≥ D ≥ 1 μm** Transitional nanochannels **1μm ≥ D ≥ 0***:***1 μm** Nanochannels **D ≥ 0***:***1 μm**

manifolds of heat sinks that the prior studies in this area are sorted and are explained in detail, and a comprehensive table is presented for each section. Also, working fluids (nano-fluids, phase change materials (PCMs) slurries, and boiling flows) are investigated as subsections of flow parameters. Besides, almost all micro heat sink applications in real life are characterized and the most significant of them, such as PCs and laptops, PCRs, gaming consoles, and data servers, are explained in detail, and other applications are listed. Finally, the suggestions and future direction

working fluids [4].

*Advances in Microfluidics and Nanofluids*

Previous research indicates that changing pattern plays a fundamental role in enhancing the heat transfer rate [4]. The concept of periodic renewal of thermal boundary layers is a useful technique for enhancing heat transfer. Besides, secondary flows and fluid mixing are considered other factors for heat transfer enhancement that can be formed in pattern design.

Furthermore, research has shown that increasing heat transfer will reduce the pressure drop penalty [2, 3, 36]. Therefore, setting a balance between the heat transfer enhancement and the pressure drop penalty is required for discovering the optimum pattern design. Some relations, such as efficiency index (ɳ) and Performance Evaluation Criteria (PEC), could help to identify these crucial parameters [37].

Several works studied the impact of pattern designs on heat transfer including, periodic (wavy, zigzag, etc.) [38–42], serpentine [43, 44], pin-fin [45, 46], and oblique [47–50] and most efficient pattern designs are summarized in **Table 2**.

The impact of the microchannel heat sink's pattern on thermal performance was investigated numerically by Lin et al. [51]. They reported that due to dean vortices formation in the channel's cross-section, the fluid mixing enhanced, and the thermal boundary layers' thickness decreased. Therefore, wavy heat sinks had better thermal performance compared to conventional straight heat sink due to higher Nusselt number and lower thermal resistance. After Lin et al. [51], another research group, Sui et al. [38] investigated the effect of wave amplitudes in wavy microchannel shown in **Figure 1**. Results illustrated that with increasing the amplitude to wavelength ratio (relative waviness), the thermal performance increased compared to the straight microchannel.


Mohammed et al. [60] numerically investigated the effect of different geometric patterns (zigzag, curvy, and step) on the heat transfer characteristics. The hydraulic- thermal characteristics (temperature profile, heat transfer coefficient, pressure drop, friction factor, and wall shear stress) were compared between considered patterns. They found that the highest heat transfer coefficient and the pressure drop belong to the zigzag, wavy, and curvy pattern, respectively. The step pattern obtains the lowest heat transfer coefficient and pressure drop; however, it was still higher than the conventional straight pattern. The main reason for the heat transfer enhancement is the periodic renewal of boundary layers. These boundary layers disturb by the formation of recirculation flow around the corners in the zigzag pattern and dean vortices' formation in the wavy and curvy patterns. Thus, the zigzag and the step were the best patterns for achieving the optimum hydraulic-

*Top view of wavy microchannels with (a) constant wavelength, (b) decreasing wavelength, and (c) shorter*

**Pattern Size of heat sink Re/Flow**

W = 13 mm L = 21 mm

*Note. MCHS: microchannel heat sink, PFHS: pin-fin heat sink, L: Length, W: Width, N.A: Not Applicable/Not Available, SPSM: Single path serpentine microchannel, DPSM: Double path serpentine microchannel,TPSM: Triple path serpentine microchannel, SMHS: Smooth straight mini-channel heat sink, SMHS-SP: SMHS with straight pinfins, SMHS-WP: SMHS with wavy pin-fins, WMHS: Smooth wavy mini-channel heat sink, WMHS-SP: WMHS*

*Effective Parameters on Increasing Efficiency of Microscale Heat Sinks and Application…*

**rate**

500 to 10,000

**Heat flux/ Power input**

> <sup>q</sup>″ =2 (kW/m<sup>2</sup> )

Junye and Hugh Wang [61] numerically investigated the effect of different layout configurations on the flow distribution and pressure drop. They simulated six configurations, including single serpentine, multiple serpentines with two channels, multiple serpentines with three channels, multiple serpentines with six channels, straight parallel and interdigitated configurations with U-type arrangement for inlet/outlet position. They reported that less pressure drop and higher flow maldistribution (MLD) belong to a straight parallel configuration. Single serpentine had the best uniform flow distribution with a higher pressure drop, while multiple serpentine configurations had the medium pressure drop and flow MLD. Moreover, the flow MLD had decreased with the decreasing channel number. Similarly,

thermal performance, respectively [42, 60].

**Author Type**

Mir Waqas Alam et al. [59]

**Table 2.**

**Figure 1.**

**159**

*wavelength [38].*

**of heat sink**

*DOI: http://dx.doi.org/10.5772/intechopen.96467*

*Summary of studies in different types of patterns.*

PFHS triangular shape micro-pin-fin

*with straight pin-fins, WMHS-WP: WMHS with wavy pin-fins.*

*Effective Parameters on Increasing Efficiency of Microscale Heat Sinks and Application… DOI: http://dx.doi.org/10.5772/intechopen.96467*


*Note. MCHS: microchannel heat sink, PFHS: pin-fin heat sink, L: Length, W: Width, N.A: Not Applicable/Not Available, SPSM: Single path serpentine microchannel, DPSM: Double path serpentine microchannel,TPSM: Triple path serpentine microchannel, SMHS: Smooth straight mini-channel heat sink, SMHS-SP: SMHS with straight pinfins, SMHS-WP: SMHS with wavy pin-fins, WMHS: Smooth wavy mini-channel heat sink, WMHS-SP: WMHS with straight pin-fins, WMHS-WP: WMHS with wavy pin-fins.*

#### **Table 2.**

**Author Type**

Lin Lin et al. [51]

Ahmad F. Al-Neama et al.

Yogesh K. Prajapati [52]

Mushtaq Ismael Hasan [53]

Zohreh Chamanroy and Morteza Khoshvaght-Aliabadi [54]

Lei Chai and Liang Wang [55]

Dawei Yang et al. [56]

Zekeriya Parlak

Fatima Zohra Bakhti and Mohammad Si-Ameur [57]

Pahlevaninejad et al. [58]

[42]

N.

**158**

[43]

M. Khoshvaght-Aliabadi et al. [41]

**of heat sink**

*Advances in Microfluidics and Nanofluids*

Y.Sui et al. [38] MCHS Wavy & Straight

pattern

MCHS Zigzag pattern with rectangular, triangular, and circular nook

MCHS Serpentine (SPSM, DPSM, TPSM) & Straight rectangular pattern

MCHS rectangular

MCHS Interrupted

MCHS Five different

PFHS Triangle, square, pentagon, hexagon and circle geometries

MCHS Zigzag, straight and wavy pattern

PFHS circular perforated pin fin

MCHS wavy pattern with rectangular obstacles

PFHS Square, triangular and circular

plate-fin

straight and wavy: SMHS, SMHS-SP, SMHS-WP 1, SMHS-WP 2, WMHS, WMHS-SP, WMHS-WP 1, and WMHS-WP 2

configurations of ribs: rectangular, backward triangular, diamond, forward triangular and ellipsoidal

MCHS Wavy W = 10 mm

**Pattern Size of heat sink Re/Flow**

L = 14 mm

W = 45 mm L = 41 mm

W = 3.7 mm L = 15 mm

W = 6 mm L = 16 mm

W = 1 mm L = 100 mm

W = 0.25 mm L = 10 mm

W = 10 mm L = 10 mm

N.A. Inlet

N.A. 5, 50, 150

**rate**

N.A. <sup>100</sup>–<sup>800</sup> <sup>q</sup><sup>00</sup> <sup>¼</sup> <sup>1</sup>*:*<sup>5</sup> � 106

Flow Rate= 0.1, 0.2 to 1 L/min

> 100– 1000

W = 20 mm L = 100 mm 10–900 N.A.

**Heat flux/ Power input**

And 1*:*5 � 10<sup>6</sup> W*=*m<sup>2</sup>

Heat power = 100 W

N.A.

)

<sup>300</sup>–<sup>800</sup> <sup>q</sup><sup>00</sup> <sup>¼</sup> 100 W*=*cm2

<sup>100</sup>–800 q″ = 100 to 500 (kW/m<sup>2</sup> )

<sup>100</sup>–700 q″ = 106 (W/m<sup>2</sup>

Re = 2122 N.A.

<sup>q</sup>″ =2 �<sup>106</sup> (W/m<sup>2</sup> )

= 300 W

<sup>q</sup>″ =50000 (W/m<sup>2</sup> )

velocity = 0.5 to 5 m/s

N.A. 100–400 Heat power

and 300

100–900 N.A.

*Summary of studies in different types of patterns.*

**Figure 1.**

*Top view of wavy microchannels with (a) constant wavelength, (b) decreasing wavelength, and (c) shorter wavelength [38].*

Mohammed et al. [60] numerically investigated the effect of different geometric patterns (zigzag, curvy, and step) on the heat transfer characteristics. The hydraulic- thermal characteristics (temperature profile, heat transfer coefficient, pressure drop, friction factor, and wall shear stress) were compared between considered patterns. They found that the highest heat transfer coefficient and the pressure drop belong to the zigzag, wavy, and curvy pattern, respectively. The step pattern obtains the lowest heat transfer coefficient and pressure drop; however, it was still higher than the conventional straight pattern. The main reason for the heat transfer enhancement is the periodic renewal of boundary layers. These boundary layers disturb by the formation of recirculation flow around the corners in the zigzag pattern and dean vortices' formation in the wavy and curvy patterns. Thus, the zigzag and the step were the best patterns for achieving the optimum hydraulicthermal performance, respectively [42, 60].

Junye and Hugh Wang [61] numerically investigated the effect of different layout configurations on the flow distribution and pressure drop. They simulated six configurations, including single serpentine, multiple serpentines with two channels, multiple serpentines with three channels, multiple serpentines with six channels, straight parallel and interdigitated configurations with U-type arrangement for inlet/outlet position. They reported that less pressure drop and higher flow maldistribution (MLD) belong to a straight parallel configuration. Single serpentine had the best uniform flow distribution with a higher pressure drop, while multiple serpentine configurations had the medium pressure drop and flow MLD. Moreover, the flow MLD had decreased with the decreasing channel number. Similarly,

Al-Neama et al. [43] experimentally and numerically investigated the thermal performance of different serpentine patterns with straight rectangular microchannels (**Figure 2**). Results showed that the highest heat transfer belonged to Single path serpentine microchannel, followed by Double path serpentine microchannel and Triple path serpentine microchannel.

Many researchers in recent years studied the impact of different pin-fin patterns in heat sinks. A heat sink's performance can be enhanced by using different pin-fin patterns in which secondary flows and fluid mixing can be formed. The effects of using oblique fin pattern on the thermo-hydraulic performance of microchannel heat sink were studied by Yong-Jiun Le [45]. They reported that the oblique fin pattern gained a higher heat transfer performance enhancement of about 47% compared to the conventional microchannel due to the secondary flow generation and redevelopment of boundary layers.

Evaluation of thermal performance in hexagonal pin-fin heat sink was studied by S. Subramanian et al. [45]. The results revealed that the hexagonal fins achieved a higher heat transfer rate compared to the conventional straight microchannel. The significant reason for heat transfer enhancement is the formation of recirculation flow zone around the pin-fins, increasing the fluid mixing and disturbs the thermal boundary layer.

The effect of several aspect ratios on microchannel heat sinks' performance was studied numerically by Alfaryjat et al. [64]. They found that the highest heat transfer coefficient and the lowest pressure drop belong to the hexagonal and

*Effective Parameters on Increasing Efficiency of Microscale Heat Sinks and Application…*

*(a) Shape of microchannel cross-section and (b) shape of micro pin-fin cross-section.*

Evaluation of thermal performance in the micro-pin heat sink with various cross-section shapes was studied by Hasan [53]. The results revealed that the circular fins present a higher heat transfer rate compared to other fins. The square has the highest pressure drop, while it is the lowest for circular cross-section. Besides, in another research, Tehmina Ambreen et al. [65] numerically investigated the effect of different cross-section shapes (circular, square, and hexagonal) on the micro pinfin heat sink thermal performance. Their results showed that the upstream fins row considerably influences the heat sink flow distribution and thermal performance. Moreover, circular fins showed the highest thermal performance (Nuave = 10), followed by hexagon and square fins, whereas square fins showed the smallest

Dawei Yang et al. [56] illustrated that pin-fins with triangular cross-sections create the maximum blocking region in the fins back-side area, reducing the heat transfer rate of the heat sink increases the pressure drop. The circular cross-section had the minimum blocking region and pressure drop. Furthermore, the hexagonal shape has a flow-guided effect, which conducts the coolant into the back area;

Another evaluation of the pin-fin thermal–hydraulic performance of heat sinks belongs to Yang et al. [66], and their results showed that the sine shape's presented better heat transfer than hydrofoil and rhombus due to high fluid mixing. Besides, the rhombus has a maximum pressure drop because the flow path was smaller than other cases, while the pressure drop is minimum in the sine shape. Furthermore, due to the minimum stagnation area around the sine pin-fin heat sink, this one obtains the highest thermal performance. In a similar study, Ambreen et al. [67] investigated the effect of different micro-pin shapes on the heat sink's thermal performance. Results showed that the highest heat transfer rate belonged to circular pin-fin, followed by square and triangular shape. They demonstrated that the largest separation area happens behind the square and triangular pin-fins, and the circular had the least separation region, which contributes to the optimized thermal performance of the circular pin-fins (**Figure 4**). **Table 3** summarized the different

circular cross-section, respectively.

*DOI: http://dx.doi.org/10.5772/intechopen.96467*

**Figure 3.**

thermal performance values (Nuave = 7).

types of cross-sections.

**161**

consequently, it has the best heat transfer performance.

#### *3.1.2 Cross-sections*

The shape of the cross-section plays a vital role in heat sink performance. The micro pin-fin/channel cross-section can affect the flow characteristics like flow distribution, thermal resistance, secondary flow generation, maximum wall temperature, and thermal resistance, which can influence the heat transfer and pressure drop [8].

Generally, the cross-section shape is divided into two parts, (i) shape of microchannel cross-section (ii) shape of micro pin-fin cross-section; **Figure 3** shows different microchannel and micro pin-fins cross-sectional shape.

Gunnasegaran et al. [62] numerically investigated the effect of rectangular, triangular, and trapezoidal cross-section shapes on the microchannel heat transfer characteristics. The results showed that the rectangular cross-section gains the best maximum heat transfer coefficient of about 9.65 at the maximum Reynolds number (Re = 1000); while, the triangular shape showed the lowest heat transfer coefficient (9.38). In another study, Wang et al. [63] reported that the rectangular shape had the maximum, and the triangular shape had the minimum pressure drops.

#### **Figure 2.**

*Actual views of a serpentine microchannel with different layout configurations: (a) single, (b) double and (c) triple path multi-serpentine [43].*

*Effective Parameters on Increasing Efficiency of Microscale Heat Sinks and Application… DOI: http://dx.doi.org/10.5772/intechopen.96467*

**Figure 3.** *(a) Shape of microchannel cross-section and (b) shape of micro pin-fin cross-section.*

The effect of several aspect ratios on microchannel heat sinks' performance was studied numerically by Alfaryjat et al. [64]. They found that the highest heat transfer coefficient and the lowest pressure drop belong to the hexagonal and circular cross-section, respectively.

Evaluation of thermal performance in the micro-pin heat sink with various cross-section shapes was studied by Hasan [53]. The results revealed that the circular fins present a higher heat transfer rate compared to other fins. The square has the highest pressure drop, while it is the lowest for circular cross-section. Besides, in another research, Tehmina Ambreen et al. [65] numerically investigated the effect of different cross-section shapes (circular, square, and hexagonal) on the micro pinfin heat sink thermal performance. Their results showed that the upstream fins row considerably influences the heat sink flow distribution and thermal performance. Moreover, circular fins showed the highest thermal performance (Nuave = 10), followed by hexagon and square fins, whereas square fins showed the smallest thermal performance values (Nuave = 7).

Dawei Yang et al. [56] illustrated that pin-fins with triangular cross-sections create the maximum blocking region in the fins back-side area, reducing the heat transfer rate of the heat sink increases the pressure drop. The circular cross-section had the minimum blocking region and pressure drop. Furthermore, the hexagonal shape has a flow-guided effect, which conducts the coolant into the back area; consequently, it has the best heat transfer performance.

Another evaluation of the pin-fin thermal–hydraulic performance of heat sinks belongs to Yang et al. [66], and their results showed that the sine shape's presented better heat transfer than hydrofoil and rhombus due to high fluid mixing. Besides, the rhombus has a maximum pressure drop because the flow path was smaller than other cases, while the pressure drop is minimum in the sine shape. Furthermore, due to the minimum stagnation area around the sine pin-fin heat sink, this one obtains the highest thermal performance. In a similar study, Ambreen et al. [67] investigated the effect of different micro-pin shapes on the heat sink's thermal performance. Results showed that the highest heat transfer rate belonged to circular pin-fin, followed by square and triangular shape. They demonstrated that the largest separation area happens behind the square and triangular pin-fins, and the circular had the least separation region, which contributes to the optimized thermal performance of the circular pin-fins (**Figure 4**). **Table 3** summarized the different types of cross-sections.

Al-Neama et al. [43] experimentally and numerically investigated the thermal performance of different serpentine patterns with straight rectangular microchannels (**Figure 2**). Results showed that the highest heat transfer belonged to Single path serpentine microchannel, followed by Double path serpentine microchannel and

Many researchers in recent years studied the impact of different pin-fin patterns in heat sinks. A heat sink's performance can be enhanced by using different pin-fin patterns in which secondary flows and fluid mixing can be formed. The effects of using oblique fin pattern on the thermo-hydraulic performance of microchannel heat sink were studied by Yong-Jiun Le [45]. They reported that the oblique fin pattern gained a higher heat transfer performance enhancement of about 47% compared to the conventional microchannel due to the secondary flow generation

Evaluation of thermal performance in hexagonal pin-fin heat sink was studied by S. Subramanian et al. [45]. The results revealed that the hexagonal fins achieved a higher heat transfer rate compared to the conventional straight microchannel. The significant reason for heat transfer enhancement is the formation of recirculation flow zone around the pin-fins, increasing the fluid mixing and disturbs the thermal

The shape of the cross-section plays a vital role in heat sink performance. The micro pin-fin/channel cross-section can affect the flow characteristics like flow distribution, thermal resistance, secondary flow generation, maximum wall temperature, and thermal resistance, which can influence the heat transfer and pressure drop [8]. Generally, the cross-section shape is divided into two parts, (i) shape of microchannel cross-section (ii) shape of micro pin-fin cross-section; **Figure 3** shows

Gunnasegaran et al. [62] numerically investigated the effect of rectangular, triangular, and trapezoidal cross-section shapes on the microchannel heat transfer characteristics. The results showed that the rectangular cross-section gains the best maximum heat transfer coefficient of about 9.65 at the maximum Reynolds number (Re = 1000); while, the triangular shape showed the lowest heat transfer coefficient (9.38). In another study, Wang et al. [63] reported that the rectangular shape had

the maximum, and the triangular shape had the minimum pressure drops.

*Actual views of a serpentine microchannel with different layout configurations: (a) single, (b) double and*

different microchannel and micro pin-fins cross-sectional shape.

Triple path serpentine microchannel.

*Advances in Microfluidics and Nanofluids*

and redevelopment of boundary layers.

boundary layer.

*3.1.2 Cross-sections*

**Figure 2.**

**160**

*(c) triple path multi-serpentine [43].*

*3.1.3 Manifolds*

optimal performance.

Applicable/Not Available.

**Figure 5.**

A.B. Datta et al.

S.S. Sehgal et al.

Chi-Chuan wang et al. [80]

[78]

[79]

**163**

improved flow MLD at high flow rates.

*DOI: http://dx.doi.org/10.5772/intechopen.96467*

Designing the manifolds is another primary geometrical parameter that researchers focus on to achieve a high-performance heat sink. Studying manifolds can be classified into three categories, including (a) location of inlet and outlet, (b) fluid inlet and outlet configuration (horizontal or vertical), and (c) header shape types. Some differences between experimental and theoretical results have been reported due to the maldistribution (MLD) in microchannel's branches and forming non-uniform temperature distribution in the edges of multiple microchannels. On the other hand, no difference was observed in single microchannels' results [72–75]. So, it can be concluded that an essential goal of studying manifolds is to achieve uniform flow and temperature distribution and remove hot spots for obtaining

*Effective Parameters on Increasing Efficiency of Microscale Heat Sinks and Application…*

Anbumeenakshi and Thansekhar [76] experimentally examined the effect of header shapes and inlet configurations in flow MLD in a rectangular microchannel heat sink (**Figure 5**). Results illustrated that trapezoidal and triangular types showed better flow uniformity at low flow rates. Also, the rectangular header

Xia et al. [77] analyzed the effects of three inlet and outlet flow arrangements (I, C, and Z-type), as well as header shapes (triangular, trapezoidal, and rectangular). The results illustrate that the I-type arrangement generated a uniform flow distribution compared to other configurations. Similarly, the rectangular header shape produced better flow uniformity than other headers. Critical parameters for

Note. H: Horizontal, V: Vertical, Min: Minimum, Max: Maximum, Rec: Rectan-

gular, Trp: Trapezoidal, Tri: Triangular, MLD: Maldistribution, and N.A: Not

*Different header shape and inlet configurations. (a) Trapezoidal-inline. (b) Rectangular-inline. (c) Triangular-inline. (d) Trapezoidal-vertical. (e) Rectangular-vertical. (f) Triangular-vertical [76].*

**type**

**Outlet type**

U/Z/Mixed-type H/H/H H/H/H N.A. Mixed

P/U/S-type V/H/H V/H/H N.A. S-type

U/Z-type H/H H/H Z-type U-type

**Max MLD Min MLD**

**Author Parameters Inlet**

flow distribution in the manifold are summarized in **Table 4**.

**Figure 4.**

*Flow streamline of (a) square, (b) circular, and (c) triangular micro pin-fin [67].*


#### **Table 3.**

*Summary of some studies in a different type of cross-sections.*

According to results, a microchannel with a rectangular cross-section presented maximum performance compared to other microchannel cross-sections. The shape with no sharp corners obtains higher performance in micro pin-fins. It is hard to conclude precisely the best cross-section because the applied conditions play a significant role in micro pin-fin/channels heat sink performance.

*Effective Parameters on Increasing Efficiency of Microscale Heat Sinks and Application… DOI: http://dx.doi.org/10.5772/intechopen.96467*
