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 Nut = 0.43 Re8 P,04 The air flowing over the surface has a temperature of 290 K, a velocity of 10 m/s, and is completely dry ( = 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
icon
Related questions
Question

Include a free body diagram and assumptions before solving 

### 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 the following properties:
- Temperature: 290 K
- Velocity: 10 m/s
- Humidity: Completely dry (\(\phi = 0\))

The specifications of the surface are:
- Length: 1 m
- Surface area: 1 m²

Enough energy is supplied to maintain a steady-state temperature of 310 K on the surface.

#### Questions:

(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:

To solve this problem, consider the following:

- **Heat Transfer Coefficient**: Use the Nusselt number correlation to find the heat transfer coefficient.
- **Convection Rate**: Evaluate the rate of heat loss using the heat transfer coefficient and the temperature difference.
- **Mass Transfer Coefficient**: Use appropriate relations to find the mass transfer coefficient.
- **Evaporation Rate**: Calculate based on the mass transfer coefficient and the given conditions.
- **Required Heat Supply**: Determine the energy input needed to maintain the steady-state temperature.
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 the following properties: - Temperature: 290 K - Velocity: 10 m/s - Humidity: Completely dry (\(\phi = 0\)) The specifications of the surface are: - Length: 1 m - Surface area: 1 m² Enough energy is supplied to maintain a steady-state temperature of 310 K on the surface. #### Questions: (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: To solve this problem, consider the following: - **Heat Transfer Coefficient**: Use the Nusselt number correlation to find the heat transfer coefficient. - **Convection Rate**: Evaluate the rate of heat loss using the heat transfer coefficient and the temperature difference. - **Mass Transfer Coefficient**: Use appropriate relations to find the mass transfer coefficient. - **Evaporation Rate**: Calculate based on the mass transfer coefficient and the given conditions. - **Required Heat Supply**: Determine the energy input needed to maintain the steady-state temperature.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps with 2 images

Blurred answer
Knowledge Booster
Convection
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.
Similar questions
Recommended textbooks for you
Elements Of Electromagnetics
Elements Of Electromagnetics
Mechanical Engineering
ISBN:
9780190698614
Author:
Sadiku, Matthew N. O.
Publisher:
Oxford University Press
Mechanics of Materials (10th Edition)
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:
9780134319650
Author:
Russell C. Hibbeler
Publisher:
PEARSON
Thermodynamics: An Engineering Approach
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:
9781259822674
Author:
Yunus A. Cengel Dr., Michael A. Boles
Publisher:
McGraw-Hill Education
Control Systems Engineering
Control Systems Engineering
Mechanical Engineering
ISBN:
9781118170519
Author:
Norman S. Nise
Publisher:
WILEY
Mechanics of Materials (MindTap Course List)
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:
9781337093347
Author:
Barry J. Goodno, James M. Gere
Publisher:
Cengage Learning
Engineering Mechanics: Statics
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:
9781118807330
Author:
James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:
WILEY