DIRECT -CONTACT HEAT TRANSFER

DIRECT -CONTACT HEAT TRANSFER

DIRECT -CONTACT HEAT TRANSFER Edited by Frank Kreith Solar Energy Research Institute Golden, Colorado and University of Colorado, Boulder R. F. Boehm University of Utah Salt Lake City Springer-Verlag Berlin Heidelberg GmbH

DIRECT-CONTACT HEAT TRANSFER Springer-Verlag Berlin Heidelberg 1988 Originally published by Hemisphere Publishing Corporation. New York in 1988 All rights reserved. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publisher. 1234567890 BRBR 898 Library of Congress Cataloging-in-Publication Data Direct contact heat transfer. Presentations made at a workshop on direct contact heat transfer at the Solar Energy Research Institute, Golden, Colorado, in the summer of 1985. Bibliography: p. Includes indexes. 1. Heat exchangers Congresses. 2. Heat- Transmission Congresses. 3. Two-phase flow Congresses. I. Kreith, Frank, n. Boehm, R. F. TJ263.D55 1987 621.402'2 87-12058 ISBN 978-3-662-30184-5 ISBN 978-3-662-30182-1 (ebook) DOI 10.1007/978-3-662-30182-1

CONTENTS Contributors Preface ix xi 1 DIRECT-CONTACT HEAT TRANSFER PROCESSES R. F. Boehm and Frank Kreith Introduction 2 Direct-Contact Devices and Application 3 Classifications of Direct-Contact Heat Transfer Processes 4 Heat Transfer Mechanisms 5 Organization and Overview 1 3 9 19 22 24 2 INDUSTRIAL PRACTICES AND NEEDS James R. Fair 1 Computational Approach 2 Transfer Models 3 Performance Characteristics of Equipment 4 Research Needs Nomenclature 25 27 30 33 36 37 39 3 COMPUTATIONAL TECHNIQUES FOR TWO-PHASE FLOW AND HEAT TRANSFER C. T. Crowe 2 Numerical Model Classification 41 41 43 v

vi CONTENTS 3 Grouping According to Physical Models 4 Basic Equations for Multiphase Momentum and Energy Transport 5 Computational Models 6 Conclusion 44 47 51 58 58 4 INDUSTRIAL PRACTICES AND TWO-PHASE TRANSPORT James G. Knudson 1 Session 1. Industrial Practices and Needs 2 Session 2. Computational Techniques for Two-Phase Flow and Heat Transfer 61 61 63 5 MASS TRANSFER EFFECTS IN HEAT TRANSFER PROCESSES J. J. Perona 2 Example I-Geothermal Power Cycle 3 Example 2-Fischer-Tropsch Synthesis in a Fluidized Bed 4 Formulation of Rate Equations 5 Analogies 6 Interfacial Area 7 Gas-Liquid Systems 8 Liquid-Liquid Systems 9 Fluid-Particle Systems Nomenclature 67 67 67 70 71 73 74 76 77 78 79 81 6 LIQUID-LIQUID PROCESSES R. Letan I Contactors in Liquid-Liquid Processes 2 Mechanisms of Vertical Moving Systems 3 Heat and Mass Transfer 4 Design Relations and Applications Nomenclature 83 83 85 98 104 115 116 7 DISCUSSION OF MASS TRANSFER EFFECTS AND LIQUID-LIQUID TRANSPORT E. Marschall 2 Recommendations for Basic Research 3 Recommendations for Design and Operation of Direct-Contact Equipment 4 Conclusion 119 119 120 124 125 125

CONTENTS vii 8 SOLIDS MOTION AND HEAT TRANSFER IN GAS FLUIDIZED BEDS Michael M. Chen 2 Solids Motion in the Fluidized Bed 3 Results and Discussion 4 Mixing Process in the Bed 5 Heat Transfer to Immersed Surfaces 6 Concluding Remarks Acknowledgement 127 127 131 138 146 148 162 163 163 9 HIGH TEMPERATURE SOLIDS-GAS INTERACTIONS M. Q. Brewster 1 Scope 2 Overview 3 Review of Recent Experimental Studies 4 Pertinent Radiative Modeling Techniques 5 Effect of Important Variables on Radiative Transport 6 Summary and Recommendations 167 168 168 169 175 189 191 198 10 DIRECT -CONTACT HEAT TRANSFER IN SOLID-GAS SYSTEMS James R. ~ l t y Fluid Flow Mechanistic Considerations 2 Theoretical Models 3 Experimental Programs 4 Conclusions and Challenges 197 198 199 200 201 11 DIRECT -CONTACT EVAPORATION D. Bharathan 2 Interfacial Processes 3 Simultaneous Heat and Mass Transfer 4 Evaporation Applications 5 Concluding Remarks 12 DIRECT -CONTACT CONDENSATION Harold R. Jacobs 2 Drop-Type Condensers 3 Jet- and Sheet-Type Condensers 4 Film-Type Condensers 5 Bubble-Type Condensers 203 203 204 206 208 221 221 223 223 224 228 230 232 234

viii CONTENTS 13 DISCUSSION OF DIRECT-CONTACT CONDENSATION AND EVAPORATION A. F. Mills Introduction 2 Summary of the Discussion 3 Further Comments on the Contributed Papers 4 Research and Development Needs 5 Conclusions 237 237 237 238 240 242 242 14 RESEARCH NEEDS IN DIRECT -CONTACT HEAT EXCHANGE R. F. Boehm and Frank Kreith 2 Areas Where Research Is Needed 3 Conclusion 245 245 246 251 APPENDIXES 1 Example Calculations for Mass Transfer Effects J. J. Perona 2 Air/Molten Salt Direct-Contact Heat Transfer Analysis Mark S. Bohn 3 Design of Direct-Contact Preheater/Boilers for Solar Pond Power Plants John D. Wright 4 Design of a Direct-Contact Liquid-Liquid Heat Exchanger R. Letan 5 Thermal and Hydraulic Design of Direct-Contact Spray Columns for Use in Extracting Heat from Geothermal Brines Harold R. Jacobs 6 Thermal Design of Water Cooling Towers J. C. Campbell Author Index Subject Index 253 257 299 335 343 371 391 397

CONTRIBUTORS D. BHARATHAN Solar Energy Research Institute 1617 Cole Boulevarde Golden, CO 80401 R. F. BOEHM Department of Mechanical Engineering University of Utah Salt Lake City, UT 84112 MARKS. BOHN Solar Energy Research Institute 1617 Cole Boulevarde Golden, CO 8040 1 M. Q. BREWSTER Department of Mechanical Engineering University of lllinois at Urbana-Champaign 1206 West Green Street Urbana, IL 61801 JOHN C. CAMPBELL Professional Engineer 1217 Derbyshire Drive Ballwin, MO 63021 MICHAEL M. CHEN Department of Mechanical Engineering University of lllinois at Urbana-Champaign 1206 West Green Street Urbana, IL 61801 C. T. CROWE Engineering International Suite 200 301-116 Avenue, S.E. Bellevue, WA 99004; and Mechanical Engineering Department Washington State University Pullman, WA 99164 JAMES R. FAIR Department of Chemical Engineering The University of Texas Austin, TX 78712 ix

xii PREFACE to increase the use of direct contact processes, the National Science Foundation supported a workshop on direct contact heat transfer at the Solar Energy Research Institute in the summer of 1985. We served as organizers for this workshop, which emphasized an area of thermal engineering that, in our opinion, has great promise for the future, but has not yet reached the point of wide-spread commercial application. Hence, a summary of the state of knowledge at this point is timely. The workshop had a dual objective: 1. To summarize the current state of knowledge in such a form that industrial practitioners can make use of the available information. 2. To indicate the research and development needed to advance the state-of-the-art, indicating not only what kind of research is needed, but also the industrial potential that could be realized if the information to be obtained through the proposed research activities were available. In order to achieve these objectives, we invited some of the leading researchers, engineers and practitioners in the field of direct-contact heat transfer for a two-day workshop to discuss the key issues in the field. The workshop consisted of 8 lectures and 4 discussion sessions. Each discussion session dealt with two related lecture topics. The lectures were tutorial in nature, thus presenting the best available correlation of data and summaries of techniques in the field and also showing how this information could be used for practical applications in industry. We have attempted to summarize all the information on research needs from this workshop as the final chapter in this book for the use of the engineering research community and funding agencies. After completing the workshop, we decided that it would be helpful if in addition to the technical summaries, there would also be appendixes that would illustrate the manner in which direct-contact heat transfer devices can be designed and evaluated. Searching for readily available information, we found that a majority of applications of direct-contact processes have been made in areas in which energy use and efficiency of utilization is at a premium. These areas are in the evolving fields of energy conservation and renewable energy conversion, where often low grade energy sources must be utilized and high second law thermodynamic efficiencies are required in order to make these processes viable. Hence, the examples in the appendixes are chosen from energy production in a geothermal installation, energy conversion in a solar pond application, energy conversation in open cycle OTEC, and in a cooling tower. However, these illustrative examples are not intended to be exhaustive, but rather to provide a background for other applications that imaginative engineers and designers can utilize. We hope that the presentations from eminent authorities in the field that we have collected here will serve the engineering community and that the appendix material will help in generating more applications of direct-contact heat transfer processes. Frank Kreith R. F. Boehm

DIRECT -CONTACT HEAT TRANSFER