Static Mixing Spacers for Spiral Wound Modules
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Desalination and Water Purification Research and Development Program Report No. 161 Static Mixing Spacers for Spiral Wound Modules U.S. Department of the Interior Bureau of Reclamation Technical Service Center Denver, Colorado November 2012 Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) November 2012 Final 2010-2012 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Static Mixing Spacers for Spiral Wound Modules Agreement No.R10AP81213 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Glenn Lipscomb 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Chemical Engineering Task Identification Number University of Toledo Task IV: Expanding Scientific 3048 Nitschke Hall (MS 305) Understanding of Desalination Processes 1610 N Westwood Ave Subtask: Increase of rates of mass transfer Toledo, OH 43607 to membrane or to heat transfer surfaces. +1 419 530-8088 [email protected] 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) Bureau of Reclamation Reclamation U.S. Department of the Interior Denver Federal Center 11. SPONSOR/MONITOR'S REPORT NUMBER(S) PO Box 25007, Denver, CO 80225-0007 DWPR Report No. 161 12. DISTRIBUTION/AVAILABILITY STATEMENT Online at https://www.usbr.gov/research/dwpr/DWPR_Reports.html 13. SUPPLEMENTARY NOTES 14. ABSTRACT A novel static mixing spacer for planar flow channels has been evaluated experimentally and theoretically. The spacer moves fluid adjacent to the surfaces of the flow channel to the middle of the channel. Such mixing should help reduce concentration polarization and mitigate fouling due to precipitation or gelation of rejected species. The mixing is fundamentally different from that produced by conventional spacers that rely upon fluid vorticity or turbulence for mixing. The results show fluid motion within the flow channel consistent with expectations. Flow visualization experiments using Computed Tomography further confirm the theoretical and experimental results. 15. SUBJECT TERMS Desalination, static mixing spacer, ultrafiltration 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF ABSTRACT OF PAGES Yuliana Porras-Mendoza a. REPORT b. ABSTRACT THIS PAGE 19b. TELEPHONE NUMBER (Include area code) U U U 303-445-2265 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 Mission Statements The U.S. Department of the Interior protects America’s natural resources and heritage, honors our cultures and tribal communities, and supplies the energy to power our future. The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. Disclaimer The views, analysis, recommendations, and conclusions in this report are those of the authors and do not represent official or unofficial policies or opinions of the United States Government, and the United States takes no position with regard to any findings, conclusions, or recommendations made. As such, mention of trade names or commercial products does not constitute their endorsement by the United States Government. Please note that this version of the report is directly from the original author. Acknowledgments [The Desalination and Water Purification Research and Development Program, Bureau of Reclamation is the sponsor of the research. Table of Contents List of Figures ................................................................................................................................ iii List of Tables ................................................................................................................................. vi Nomenclature ................................................................................................................................ vii Executive Summary ........................................................................................................................ 1 Literature Review............................................................................................................................ 5 Static Mixing Spacer Design .......................................................................................................... 8 Simulation of Spacer Performance ............................................................................................... 11 Creation of Solution Domain .................................................................................................... 12 Simulation Boundary Conditions. ............................................................................................. 16 Discretization and Solution of the Conservation Equations ..................................................... 18 Simulation Validation ............................................................................................................... 23 Simulation Results .................................................................................................................... 25 Experimental Evaluation of Spacer Performance ......................................................................... 39 Spacer Manufacture .................................................................................................................. 39 Mass Transfer Coefficient Measurements ................................................................................ 41 Pressure Drop Measurements ................................................................................................... 50 Flow Visualization .................................................................................................................... 52 Conclusions ................................................................................................................................... 56 References ..................................................................................................................................... 58 ii List of Figures Fig. 1. Illustration of typical spiral wound reverse osmosis membrane module. ........................... 2 Fig. 2. Ladder and diamond feed spacer designs. ........................................................................... 4 Fig. 3. Woven and layered spacer cross-sections. .......................................................................... 4 Fig. 4. Perspective view of proposed static mixing spacer design.................................................. 8 Fig. 5. Illustration of a partial spacer sheet created by replicating and translating the section shown in Figure 4.......................................................................................................... 9 Fig. 6. Top and bottom views of the section shown in Figure 4. .................................................... 9 Fig. 7. Cross-section A-A’ and B-B’ of Figure 6. ........................................................................ 10 Fig. 8. Top and bottom view of the fluid streamlines through the section illustrated in Fig. 4. ... 10 Fig. 9. Streamlines in sections A-A’ and B-B’. Flow is from left to right. .................................. 11 Fig. 10. Typical SolidWorks model of a spacer element. ............................................................. 13 Fig. 11. 2D projection of spacer element with design dimensions. .............................................. 13 Fig. 12. Typical solution domain used in the simulations. ........................................................... 14 Fig. 13. Typical subdivided flow domain used for meshing......................................................... 15 Fig. 14. Typical final meshed solution domain............................................................................. 16 Fig. 15. Empty channel solution domain and boundary conditions. ............................................. 23 Fig. 16. Two-dimensional solution domain for mass transfer of a dilute solute in an infinite slit. ..................................................................................................................................... 24 Fig. 17. Comparison of simulation results to analytical solutions for mass transfer in an infinite slit. ............................................................................................................................... 25 iii Fig. 18. Sherwood number dependence on Graetz number for spacers 2 and 8 as well as an empty slit. ...................................................................................................................