5.72 A cold air chamber is proposed for quenching steel ball bearings of diameter D = 0.2 m and initial temperature T₁ = 400°C. Air in the chamber is maintained at -15°C by a refrigeration system, and the steel balls pass through the chamber on a conveyor belt. Optimum bearing production requires that 70% of the initial ther- mal energy content of the ball above -15°C be removed. Radiation effects may be neglected, and the convection heat transfer coefficient within the chamber is 1000 W/m².K. Estimate the residence time of the balls within the chamber, and recommend a drive veloc- ity of the conveyor. The following properties may be used for the steel: k = 50 W/m K, a = 2 × 105 m²/s, and c = 450 J/kg. K. Ball bearing -5m- Cold air Belt V Chamber housing

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
100%
### Problem 5.72: Cold Air Chamber for Quenching Steel Ball Bearings

A cold air chamber is proposed for quenching steel ball bearings with a diameter of \( D = 0.2 \, \text{m} \) and an initial temperature of \( T_i = 400^\circ \text{C} \). The air in the chamber is maintained at \(-15^\circ \text{C}\) by a refrigeration system. The steel balls pass through the chamber on a conveyor belt. Optimum production of the bearings requires that 70% of the initial thermal energy content of the ball above \(-15^\circ \text{C}\) be removed. Radiation effects can be neglected, and the convection heat transfer coefficient within the chamber is \( 1000 \, \text{W/m}^2 \cdot \text{K} \).

**Objectives:**
- Estimate the residence time of the balls within the chamber.
- Recommend a drive velocity for the conveyor.

**Properties for Steel:**
- Thermal conductivity (\( k \)): \( 50 \, \text{W/m} \cdot \text{K} \)
- Thermal diffusivity (\( \alpha \)): \( 2 \times 10^{-5} \, \text{m}^2/\text{s} \)
- Specific heat capacity (\( c \)): \( 450 \, \text{J/kg} \cdot \text{K} \)

**Diagram Explanation:**

The diagram illustrates the setup for cooling the steel ball bearings. The key elements are:
- **Conveyor Belt**: Transports the ball bearings through the chamber.
- **Ball Bearings**: Move from left to right on the conveyor.
- **Cold Air**: Circulates within the chamber housing to cool the bearings.
- **Chamber Length**: The chamber extends 5 meters.
- **Velocity (\( v \))**: Represents the speed of the conveyor belt.

This setup is designed to efficiently transfer heat from the bearings to the cold air, ensuring optimal cooling performance as required for production.
Transcribed Image Text:### Problem 5.72: Cold Air Chamber for Quenching Steel Ball Bearings A cold air chamber is proposed for quenching steel ball bearings with a diameter of \( D = 0.2 \, \text{m} \) and an initial temperature of \( T_i = 400^\circ \text{C} \). The air in the chamber is maintained at \(-15^\circ \text{C}\) by a refrigeration system. The steel balls pass through the chamber on a conveyor belt. Optimum production of the bearings requires that 70% of the initial thermal energy content of the ball above \(-15^\circ \text{C}\) be removed. Radiation effects can be neglected, and the convection heat transfer coefficient within the chamber is \( 1000 \, \text{W/m}^2 \cdot \text{K} \). **Objectives:** - Estimate the residence time of the balls within the chamber. - Recommend a drive velocity for the conveyor. **Properties for Steel:** - Thermal conductivity (\( k \)): \( 50 \, \text{W/m} \cdot \text{K} \) - Thermal diffusivity (\( \alpha \)): \( 2 \times 10^{-5} \, \text{m}^2/\text{s} \) - Specific heat capacity (\( c \)): \( 450 \, \text{J/kg} \cdot \text{K} \) **Diagram Explanation:** The diagram illustrates the setup for cooling the steel ball bearings. The key elements are: - **Conveyor Belt**: Transports the ball bearings through the chamber. - **Ball Bearings**: Move from left to right on the conveyor. - **Cold Air**: Circulates within the chamber housing to cool the bearings. - **Chamber Length**: The chamber extends 5 meters. - **Velocity (\( v \))**: Represents the speed of the conveyor belt. This setup is designed to efficiently transfer heat from the bearings to the cold air, ensuring optimal cooling performance as required for production.
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.
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