As more and more components are placed on a single integrated circuit (chip), the amount of heat that is dissipated continues to increase. However, this increase is limited by the maximum allowable chip operating temperature. Consider a 15 mm x 15 mm square chip. In order to improve the heat dissipation, a five by five aray of copper pin fins are to be joined to the outer surface of the chip. The fins have a diameter of 1.5 mm and a length of 15 mm. Cooling air can be supplied at To = 25°C, and the maximum allowable chip base temperature is To = 75°C. The convective heat transfer coefficient is h = 250 W/m²-K, and the copper has a thermal conductivity of k = 401 W/m-K. Consider two cases: Case A: Convecting Tip, and Case B: Adiabatic Tip And for each calculate the following at steady state: (a) Heat transfer rate from a single fin. (b) Efficiency of a single fin. (c) Total heat transfer rate of the array.

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Chapter2: Steady Heat Conduction
Section: Chapter Questions
Problem 2.33P
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1. As more and more components are placed on a single integrated circuit (chip), the amount of heat that is dissipated continues to increase. However, this increase is limited by the maximum allowable chip operating temperature. Consider a 15 mm x 15 mm square chip. In order to improve the heat dissipation, a five by five array of copper pin fins are to be joined to the outer surface of the chip. The fins have a diameter of 1.5 mm and a length of 15 mm. Cooling air can be supplied at T∞ = 25°C, and the maximum allowable chip base temperature is T₀ = 75°C. The convective heat transfer coefficient is h = 250 W/m²·K, and the copper has a thermal conductivity of k = 401 W/m·K.

Consider two cases: Case A: Convecting Tip, and Case B: Adiabatic Tip

And for each calculate the following at steady state:

(a) Heat transfer rate from a single fin.
(b) Efficiency of a single fin.
(c) Total heat transfer rate of the array.
Transcribed Image Text:1. As more and more components are placed on a single integrated circuit (chip), the amount of heat that is dissipated continues to increase. However, this increase is limited by the maximum allowable chip operating temperature. Consider a 15 mm x 15 mm square chip. In order to improve the heat dissipation, a five by five array of copper pin fins are to be joined to the outer surface of the chip. The fins have a diameter of 1.5 mm and a length of 15 mm. Cooling air can be supplied at T∞ = 25°C, and the maximum allowable chip base temperature is T₀ = 75°C. The convective heat transfer coefficient is h = 250 W/m²·K, and the copper has a thermal conductivity of k = 401 W/m·K. Consider two cases: Case A: Convecting Tip, and Case B: Adiabatic Tip And for each calculate the following at steady state: (a) Heat transfer rate from a single fin. (b) Efficiency of a single fin. (c) Total heat transfer rate of the array.
### Heat Transfer from Extended Surfaces

#### Equation for Temperature Distribution:
\[ \theta = c_1 e^{mx} + c_2 e^{-mx} \]

#### Case B Boundary Conditions – Adiabatic Tip
- **At \( x = 0 \)**:  
  \[ T = T_0 \]
- **At \( x = L \)**:  
  \[ \left( \frac{dT}{dx} \right)_{x=L} = 0 \]

#### Temperature Profile Solution
\[ \frac{\theta}{\theta_0} = \frac{T - T_{\infty}}{T_0 - T_{\infty}} = \frac{e^{mx} + e^{-mx}}{1 + e^{-2mL}} \quad \text{(17-38)} \]

**or**

\[ \frac{\theta}{\theta_0} = \frac{T - T_{\infty}}{T_0 - T_{\infty}} = \frac{\cosh[m(L - x)]}{\cosh mL} \quad \text{(17-39)} \]

#### Heat Transfer Rate
\[ q = kAm\theta_0 \tanh mL \quad \text{(17-45)} \]

#### Diagram Explanation
The diagram depicts a cylindrical rod extended from a surface, illustrating the heat transfer scenario. An adiabatic tip is shown, indicating no heat flow at the tip, which relates to the boundary conditions described above. The solution equations provide the temperature distribution and heat transfer rate for this type of setup.
Transcribed Image Text:### Heat Transfer from Extended Surfaces #### Equation for Temperature Distribution: \[ \theta = c_1 e^{mx} + c_2 e^{-mx} \] #### Case B Boundary Conditions – Adiabatic Tip - **At \( x = 0 \)**: \[ T = T_0 \] - **At \( x = L \)**: \[ \left( \frac{dT}{dx} \right)_{x=L} = 0 \] #### Temperature Profile Solution \[ \frac{\theta}{\theta_0} = \frac{T - T_{\infty}}{T_0 - T_{\infty}} = \frac{e^{mx} + e^{-mx}}{1 + e^{-2mL}} \quad \text{(17-38)} \] **or** \[ \frac{\theta}{\theta_0} = \frac{T - T_{\infty}}{T_0 - T_{\infty}} = \frac{\cosh[m(L - x)]}{\cosh mL} \quad \text{(17-39)} \] #### Heat Transfer Rate \[ q = kAm\theta_0 \tanh mL \quad \text{(17-45)} \] #### Diagram Explanation The diagram depicts a cylindrical rod extended from a surface, illustrating the heat transfer scenario. An adiabatic tip is shown, indicating no heat flow at the tip, which relates to the boundary conditions described above. The solution equations provide the temperature distribution and heat transfer rate for this type of setup.
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