Over-all Heat Transfer Coefficients in Agitated Vessels

John F. Pietranski, P.E., Ph.D.

Course Outline

This four hour course will focus on deriving the general Application Equation used for calculating the over-all heat transfer coefficient in agitated vessels. Several assumptions allow for development of a shortened simplified Application Equation. The over-all coefficient is based on a relationship of the individual heat transfer coefficients within the system.

Following the Application Equation derivations, correlations are presented from the open literature which define the methodology for calculating the individual heat transfer coefficients. Jacket side heat transfer coefficient correlations for condensing vapors and for flowing liquids are included. A correlation for the agitated liquid is presented along with a table of typical fouling factors for selected fluids.

Two industrial examples are given in order to demonstrate the calculation techniques for the individual heat transfer coefficients, along with the over-all coefficient determination. The first example cools an agitated batch of hot water by utilizing chilled water in the vessel jacket. The second example heats an agitated batch of cold water by using condensing steam in the vessel jacket.

This course includes a True-False quiz at the end.

Learning Objective

It is the intention of this course to enable process engineers or other plant operations personnel to be able to calculate the over-all heat transfer coefficient in an agitated vessel being used to heat or cool a liquid. The course will explain the derivation of the Application Equation, along with assumptions that allow development of a simplified Application Equation.

Several correlations are presented from the open literature which can be utilized to determine the individual heat transfer coefficients. Other correlations are available in the literature for process situations not covered by this course. The student is encouraged to investigate these. A good starting point is reference 3.

Two examples are given: heating and cooling in a jacketed agitated vessel. The calculation techniques required by the examples will utilize all of the background covered in the Application Equation and correlation development. At the conclusion of the course the student will:

• Have an understanding of heat transfer mechanisms in a jacketed agitated vessel system used for heating or cooling.
• Be knowledgeable in the assumptions used to develop over-all heat transfer coefficients.
• Calculate individual heat transfer coefficients for condensing vapors, flowing liquids, and agitated liquids.
• Be able to calculate over-all heat transfer coefficients by using values determined from the individual heat transfer coefficients.

Course Introduction

This course provides a step-by-step development of the over-all heat transfer coefficient for agitated vessels used to heat or cool liquid batches. The course relates each of the individual heat transfer resistances found in this process into a single equation.

Several of the open literature heat transfer coefficient correlations are presented so that individual coefficients could be determined based on specified process conditions.

Two industrial examples follow the Application Equation development and the correlation review. The examples demonstrate how the over-all heat transfer coefficient is calculated from the individual coefficients.

Course Content

The course content is in a PDF file (80 KB) Over-all Heat Transfer Coefficients in Agitated Vessels. You need to open or download this document to study this course.

Course Summary

The course developed the general over-all heat transfer coefficient relationship by relating each of the individual heat transfer resistances in equation (19). This Application Equation was simplified using reasonable assumptions to equation (23) which is shown below:

1/UOver-all = 1/hA + 1/hB + 1/hDM (23)

Individual heat transfer coefficient correlations were presented so that the values of hA , hB , and hDM could be determined based on process conditions.

Two examples using a jacketed agitated vessel were given and worked through so that each individual heat transfer coefficient was calculated and used to determine the over-all heat transfer coefficient.

Related References

1. McCabe, Warren L. and Julian C. Smith, Unit Operations of Chemical Engineering, McGraw-Hill Book Company, New York, 3rd ed., 1976, p. 295.
2. McCabe, Warren L. and Julian C. Smith, Unit Operations of Chemical Engineering, McGraw-Hill Book Company, New York, 3rd ed., 1976, p. 354.
3. Don W. Green, Editor, Perry's Chemical Engineers' Handbook, McGraw-Hill Book Company, New York, 7th ed., 1997, p. 5-16.
4. Perry, Robert H. and Cecil H. Chilton, Chemical Engineer's Handbook, McGraw-Hill Book Company, New York, 5th ed., 1973, p. 10-16.
5. Kern, Donald Q., Process Heat Transfer, McGraw-Hill Book Company, New York, 1950, p. 845, and Table 12.
6. Perry, Robert H. and Cecil H. Chilton, Chemical Engineer's Handbook, McGraw-Hill Book Company, New York, 5th ed., 1973, p. 10-16 and Table 10-6.
7. Yaws, Carl L., Chemical Properties Handbook, McGraw-Hill Book Company, New York, 1999, pp. 56, 185, 472, and 531.
8. Foust, Alan S. et. al., Principles of Unit Operations, John Wiley & Sons, New York, 1960, p. 159-160.
9. Himmelblau, David M., Basic Principles and Calculations in Chemical Engineering, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1967, Appendix C: Steam Tables.

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.com or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.