6.81 An industrial process involves evaporation of a thin water film from a contoured surface by heating it from below and forcing air across it. Laboratory measure- ments for this surface have provided the following heat transfer correlation: 0.58 NuL=0.43 Re P,04 The air flowing over the surface has a temperature of 290 K, a velocity of 10 m/s, and is completely dry (6 = 0). The surface has a length of 1 m and a surface area of 1 m². Just enough energy is supplied to maintain its steady-state temperature at 310 K. (a) Determine the heat transfer coefficient and the rate at which the surface loses heat by convection. (b) Determine the mass transfer coefficient and the evaporation rate (kg/h) of the water on the surface. (c) Determine the rate at which heat must be supplied to the surface for these conditions.
6.81 An industrial process involves evaporation of a thin water film from a contoured surface by heating it from below and forcing air across it. Laboratory measure- ments for this surface have provided the following heat transfer correlation: 0.58 NuL=0.43 Re P,04 The air flowing over the surface has a temperature of 290 K, a velocity of 10 m/s, and is completely dry (6 = 0). The surface has a length of 1 m and a surface area of 1 m². Just enough energy is supplied to maintain its steady-state temperature at 310 K. (a) Determine the heat transfer coefficient and the rate at which the surface loses heat by convection. (b) Determine the mass transfer coefficient and the evaporation rate (kg/h) of the water on the surface. (c) Determine the rate at which heat must be supplied to the surface for these conditions.
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
Problem 1.1MA
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![**Problem 6.81**
An industrial process involves the evaporation of a thin water film from a contoured surface by heating it from below and forcing air across it. Laboratory measurements for this surface have provided the following heat transfer correlation:
\[
\overline{Nu}_L = 0.43 \, \text{Re}_L^{0.58} \, \text{Pr}^{0.4}
\]
The air flowing over the surface has a temperature of 290 K, a velocity of 10 m/s, and is completely dry (\(\phi_\infty = 0\)). The surface has a length of 1 m and a surface area of 1 m². Just enough energy is supplied to maintain its steady-state temperature at 310 K.
**Tasks:**
(a) **Determine the heat transfer coefficient and the rate at which the surface loses heat by convection.**
(b) **Determine the mass transfer coefficient and the evaporation rate (kg/h) of the water on the surface.**
(c) **Determine the rate at which heat must be supplied to the surface for these conditions.**
**Explanation of Concepts:**
- **Heat Transfer Coefficient:** Represents the efficiency of heat transfer through the convective process.
- **Mass Transfer Coefficient:** Defines how mass transfer occurs in systems involving a concentration difference.
- **Evaporation Rate:** The rate at which the water is transformed from liquid to vapor due to the applied heat.
**Analyses:**
- To solve for the heat transfer coefficient, employ the Nu number correlation, which links the factors impacting the convective heat transfer to physical properties and flow conditions.
- For mass transfer considerations, understand that the evaporation forms part of the heat and mass transfer phenomena at the surface.
This problem involves fluid mechanics and thermodynamics principles. Calculations will typically involve the determination of dimensionless numbers (Nu, Re, Pr) and apply them using the given correlations to solve for the desired quantities.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F03d76321-edc8-490b-8422-6ca99780ffcd%2F70dc74b3-6913-4062-a5ab-27a3b733def4%2F5e7jfrp_processed.jpeg&w=3840&q=75)
Transcribed Image Text:**Problem 6.81**
An industrial process involves the evaporation of a thin water film from a contoured surface by heating it from below and forcing air across it. Laboratory measurements for this surface have provided the following heat transfer correlation:
\[
\overline{Nu}_L = 0.43 \, \text{Re}_L^{0.58} \, \text{Pr}^{0.4}
\]
The air flowing over the surface has a temperature of 290 K, a velocity of 10 m/s, and is completely dry (\(\phi_\infty = 0\)). The surface has a length of 1 m and a surface area of 1 m². Just enough energy is supplied to maintain its steady-state temperature at 310 K.
**Tasks:**
(a) **Determine the heat transfer coefficient and the rate at which the surface loses heat by convection.**
(b) **Determine the mass transfer coefficient and the evaporation rate (kg/h) of the water on the surface.**
(c) **Determine the rate at which heat must be supplied to the surface for these conditions.**
**Explanation of Concepts:**
- **Heat Transfer Coefficient:** Represents the efficiency of heat transfer through the convective process.
- **Mass Transfer Coefficient:** Defines how mass transfer occurs in systems involving a concentration difference.
- **Evaporation Rate:** The rate at which the water is transformed from liquid to vapor due to the applied heat.
**Analyses:**
- To solve for the heat transfer coefficient, employ the Nu number correlation, which links the factors impacting the convective heat transfer to physical properties and flow conditions.
- For mass transfer considerations, understand that the evaporation forms part of the heat and mass transfer phenomena at the surface.
This problem involves fluid mechanics and thermodynamics principles. Calculations will typically involve the determination of dimensionless numbers (Nu, Re, Pr) and apply them using the given correlations to solve for the desired quantities.
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