STUDY THE RELEASE OF NITROGEN FROM COATED UREA GRANULE: MODELLING AND SIMULATION TRINH HOAI THANH DOCTOR OF PHILOSOPHY CHEMICAL ENGINEERING UNIVERSITI TEKNOLOGI PETRONAS AUGUST 2016 STATUS OF THESIS Title of thesis Study the release of nitrogen from coated urea granule: Modelling and simulation TRINH HOAI THANH I _ hereby allow my thesis to be placed at the Information Resource Center (IRC) of Universiti Teknologi PETRONAS (UTP) with the following conditions: The thesis becomes the property of UTP The IRC of UTP may make copies of the thesis for academic purposes only This thesis is classified as Confidential Ö Non-confidential If this thesis is confidential, please state the reason: _ _ _ The contents of the thesis will remain confidential for _ years Remarks on disclosure: _ _ _ Endorsed by Signature of Author Signature of Supervisor 94 A1 Hung Permanent address: Name of Supervisor Vuong, ward 9, district 5, HCMC, Assoc Prof Dr Ku Zilati Ku Shaari Vietnam Date : _ Date : UNIVERSITI TEKNOLOGI PETRONAS STUDY THE RELEASE OF NITROGEN FROM COATED UREA GRANULE: MODELLING AND SIMULATION by TRINH HOAI THANH The undersigned certify that they have read, and recommend to the Postgraduate Studies Programme for acceptance this thesis for the fulfillment of the requirements for the degree stated Signature: Main Supervisor: Assoc Prof Dr Ku Zilati Ku Shaari Signature: Co-Supervisor: "[Click Here to Enter Name]" Signature: Head of Department: Assoc Prof Dr Suriati Binti Sufian Date: STUDY THE RELEASE OF NITROGEN FROM COATED UREA GRANULE: MODELLING AND SIMULATION by TRINH HOAI THANH A Thesis Submitted to the Postgraduate Studies Programme as a Requirement for the Degree of DOCTOR OF PHILOSOPHY CHEMICAL ENGINEERING UNIVERSITI TEKNOLOGI PETRONAS BANDAR SERI ISKANDAR, PERAK AUGUST 2016 DECLARATION OF THESIS Title of thesis Study the release of nitrogen from coated urea granule: Modelling and simulation TRINH HOAI THANH I _ hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged I also declare that it has not been previously or concurrently submitted for any other degree at UTP or other institutions Witnessed by Signature of Author Signature of Supervisor 94 A1 Hung Permanent address: Name of Supervisor Vuong, ward 9, district 5, HCMC, Assoc Prof Dr Ku Zilati Ku Shaari Vietnam 09-08-2016 Date : _ 09-08-2016 Date : DEDICATION To my parent, Hoai Nam and Ha Anh, and my family for their support and patience during my research To my children for their understanding and all my love with them To my supervisor who always be the inspiration for this thesis v ACKNOWLEDGEMENTS I would like to express my deepest gratitude and appreciation to my supervisor, Dr Ku Zilati Ku Shaari, for her excellent and constant guidance, patience, generous support, and valuable advice She introduces me to the world of qualitative research and shows me how to become a good researcher Moreover, I would like to offer my most profound gratitude to OneBAJA, Centre for Biofuel and Biochemical Research, and Universiti Teknologi PETRONAS, Malaysia for providing a congenial work environment and state-of-the-art research facilities The research grant extended to us by the Ministry of Education, Malaysia (MOE) (LRGS Fasa 1/2011) for ongoing research projects and the technical support from National Institute of Forensic Medicine, Vietnam is also highly acknowledged I would like to thanks to my parent who always encourage and supporting me during my research, and also Ms Dao Nhat Quyen, the mother of my children, for her constant supporting to nurture and educate my children so that I can keep working on the research In addition, the thank also goes to Ms Tran Thi To Nga, my current wife, for being by my side through joys and pains all the time The writing suggestions shared by Dr Noridah Osman, Mr Babar Azeem, Universiti Teknologi PETRONAS, Malaysia, is highly appreciated vi ABSTRACT Urea, when applied to crops is vulnerable to losses from volatilization and leaching Controlled-release fertilizer (CRF) enhances nitrogen use efficiency by plants which not only increases the crop yields but also contributes towards environmental pollution control in terms of the alleviation of hazardous gaseous emissions and water eutrophication This study thoroughly investigates the release of nitrogen from CRF both in modeling and experimental aspects The experiments are conducted to provide useful information for the model and validation process Modeling and simulation section includes several models for each stage of the release including lag period, constant release, and decay release stages Initially, a model for water penetration into CRF that related to the lag period was proposed and developed It is successfully simulated and experimentally validated Second, a multi diffusion model was developed and simulated nitrogen release from coated urea particles for both the constant and decay release stages of urea This model was developed for multilayer included the coating and water zone, and it also integrated a finite-element method (FEM) that employed 2D geometry to enhance the accuracy of by introducing urea diffusivity in water domain as a function of urea concentration Simulation results agreed with preliminary experimental data to a standard error of estimate (SEE) that ranged from 0.0159 to 0.0567, indicating the model successfully simulated and predicted nitrogen release from hours to days and from small to large particles A more thorough investigation was then conducted for which the model not only predicted nitrogen release from coated urea but also described the internal release mechanism of urea from the core to urea-coated interface and into the aqueous environment Afterward, the model was modified and developed as a “porous” model to predict and simulate the release of nitrogen from either soils or water Imperfection of coating thickness also is taken into account in the latest model Finally, an approach has been proposed to predict/estimate the effective diffusivity of a coating vii material and to design geometric parameters for CRFs of which the release can match the nutrient uptake needs for a specific plant (i.e., Sj rice variety planting in Selangor) viii ABSTRAK Menggunakan urea untuk tanaman akan menyebabkan kerugian akibat daripada pengewapan dan larut lesap Kawalan pelepasan urea (CRF) akan meningkatkan kecekapan penggunaan nitrogen oleh tumbuh-tumbuhan yang bukan sahaja meningkatkan hasil tanaman tetapi juga menyumbang kepada kawalan pencemaran alam sekitar dari segi usaha mengurangkan pelepasan gas berbahaya dan eutrofikasi air Kajian ini dengan teliti menyiasat pelepasan nitrogen dari CRF dalam kedua-dua aspek iaitu model dan eksperimen Eksperimen dijalankan untuk menyediakan maklumat yang berguna untuk model dan pengesahan proses Bahagian pemodelan dan simulasi meliputi beberapa model untuk setiap peringkat pelepasan termasuk masa senggang, pelepasan berterusan dan peringkat penyusutan pelepasan Pada mulanya , model untuk penembusan air ke dalam CRF yang berkaitan dengan masa senggang telah dicadangkan dan dibangunkan Ia turut berjaya disimulasikan dan disahkan oleh eksperimen Kedua, model pelbagai penyebaran telah dibangunkan dan simulasikan pelepasan nitrogen dari butir urea bersalut untuk kedua-dua iaitu peringkat pelepasan berterusan dan penyusuatan urea Model ini telah dibangunkan untuk berbilang lapisan termasuk zon salutan dan air, dan mengintegrasikan Kaedah Unsur Terhingga (FEM) dengan geometri 2D untuk meningkatkan ketepatan simulasi dengan memperkenalkan kemeresapan urea dalam domain air sebagai fungsi kepekatannya Hasil keputusan simulasi selaras dengan data eksperimen awal dengan ralat piawai anggaran ( SEE ) antara 0.0159-0.0567 dan ianya menunjukkan model telah berjaya disimulasikan dan menjangkakan pelepasan nitrogen samada jam atau hari dan samada kecil atau butir besar Siasatan lebih menyeluruh kemudiannya dijalankan yang mana model bukan sahaja dapat menjangkakan pelepasan nitrogen dari urea bersalut tetapi juga menerangkan mekanisme pelepasan dalaman urea dari teras kepada antara muka urea bersalut dan ke dalam persikitaran berair Selepas itu, model diubahsuai dan dibangunkan sebagai model " berliang " untuk menjangkakan ix Trinh, T H., Ku Shaari, K Z., Basit, A., & Azeem, B (2013) Effect of Particle Size and Coating Thickness on the Release of Urea using Multi-diffusion Model 2013 2nd International Conference on Chemical Science and Engineering (ICCSE 2013) 29-30 December 2013, Kuala Lumpur, Malaysia Trinh, T H., KuShaari, K., Basit, A., Azeem, B., & Shuib, A (2013) Use of multi-diffusion model to study the release of urea from urea fertilizer coated with Polyureathane-like coating (PULC) 2013 4th International Conference on Agriculture and Animal Science (CAAS 2013) 23-24 November 2013, Phuket, Thailand A comparison between experimental and prediction simulator for controlled release fertilizer 3rd OneBAJA Students Colloquium 2014 22 May 2013, Kuala Lumpur, Malaysia Modeling the release of urea from poly-urethane-like coating urea fertilizer OneBAJA Students Colloquium 2013 12-13 September 2013, Selangor, Malaysia Modeling of Urea Release from Coated Urea for Prediction of Coating Material Diffusivity The 6th International Conference on Process Systems Engineering (PSE ASIA 2013) 25-27 June 2013, Kuala Lumpur, Malaysia 151 APPENDIX A DETERMINE APPROPRIATE FLUID SIZE FOR WATER DOMAIN USING IN THE MODEL 152 For simple cases, the analytical (mathematical) solution can be solved for the diffusion of urea to the environment However, in the case where more complex consideration factors are involved, the FEM is used instead In order to build up geometry for the release model, it is required to specify the fluid zone (water domain area) so that the accuracy of numerical solution is increased and close to the analytical solution This appendix describes how to choose an appropriate geometry for water domain by comparing results between numerical method and mathematical method under steady state condition A.1 Analytical Solution Assume that the urea particle is spherical shape, and the dissolution rate is under steady state condition Urea is quickly dissolved in the solvent and the sphere’s surface (solid urea) is saturated with the solute (dissolved urea) Since the urea particle is immersed in a large volume of fluid, its concentration away from the sphere can be considered as zero [118] The mathematical solution for urea diffusion of non-coating particle is calculated as: jD = Durea c1 (sat ) mol = 5.3910 -4 R0 m s (5.1) where Durea is the “free” diffusivity of urea in water, R0, urea radius, c1(sat), saturated urea concentration A Numerical Solution for Urea Diffusion Figure A.1 illustrates the dissolving model of a spherical urea When urea particle is immersed in water, it begins to dissolve by mean of diffusion Based on mass transport equation of urea in water, the steady state equation for urea diffusion can be written as: 153 Figure A.1: Dissolution model of a spherical urea and geometry and mesh generation for noncoated urea 154 Table A.1: Diffusive fluxes and standard deviations with analytical results of different fluid sizes for non-coated urea granule when immersed in water Fluid size 2R0 10R0 20R0 22R0 Diffusive flux, mol m-2 s-1 0.001069 6.03E-04 5.76E-04 5.61E-04 Standard deviation, % 98.16 11.84 6.74 3.91 The diffusion of non-coating urea particles are simulated with different fluid sizes: 2, 10, 20, 22 R0 where R0 is urea radius As fluid size increases, memory usage and calculation time increase From the result shown in Table A.1 and Figure 3, fluid size 22R0 had a standard deviation (STD) of 3.91% In technical term, a STD less than 5% is acceptable, the fluid size 22R0 therefore was chosen in all simulations which are used to predict the effective diffusivity coefficient of materials 155 APPENDIX B GUI PROGRAM TO PREDICT THE RELEASE OF NITROGEN FROM COATED UREA GRANULE 156 From the developed model presented, a GUI program/app is built based on COMSOL Multiphysic Apps 5.0 to assist the researchers to predict/estimate the release from coated urea granule together with instruction manual The advantages of GUI app are: i) it is easy to access and use by other researchers; One click to get results Key in parameters and click ii) Optimum parameters are automatically estimated; Results Results Determine effective diffusivity (Deff) Estimate nutrient release profile iii) The results can be exported to other software such as excel 157 0.14 0.12 Standar error estimate SEE2 0.1 0.08 0.06 Optimization chart to determine Deff and t0 0.04 0.02 0.00E+00 5.00E-14 1.00E-13 1.50E-13 2.00E-13 2.50E-13 Effective difusivity (Deff), m2/s A detailed instruction on using the program/app is demonstrated below B.1 Estimate Nitrogen Release Profile After the program is launched, it should appear as picture below 158 3.00E-13 3.50E-13 Provide an experimental data file named by browsing experiment.txt file This file contains two column are release time (in day) and nitrogen released For more detail information, kindly please refer to the example file going together with this program Enter fertilizer information regarding to geometry, lag time (t0) and estimate diffusivity (Deff) Other information should be provided as reference and plotting purpose Required parameters R0 - urea core radius in mm (through experiment or estimation) l - Coating thickness in mm (through experiment or estimation) Deff - Effective diffusivity in cm2/s (provided through experiment or analyzed) Other parameters t0 - lag time (through experiment and related to water penetration of coating material) t1 - constant release time (calculated by this program) t2 - decay release time (this parameter only affects plotting process and usually chose by estimation or through the experiments data) Accuracy index - this parameter relates to the accuracy of predicted results The higher the index, the more accurate simulation (User can choose from to 12) Click compute to analyze your case and wait until calculation progress finished Click on Release Profile or Release Rate button in Graphical illustration zone to get the relevant graphics 159 Simulation results plot Simulation results plot B.2 Estimate coating parameters Chose Parameters Estimation tab on the right side of the program as in the picture 160 Enter Lower bound, Upper bound of the parameters need to estimate, and also number of needed investigations Other parameters follow Estimate coating parameters section Click Analyze to begin calculation and obtain optimum parameters After finished, estimated coating parameters and details optimization data can be obtained from the table 161 To transfer those estimated parameters, click Transfer Data, program will transfer the data to main program for other purpose such as Estimate Nitrogen Release Profile that have been mentioned in the previous section 162 APPENDIX C GRAPHICAL IMAGES OF APPRATUS AND EQUPMENTS FOR EXPERIMENTAL VALIDATION 163 This appendix illustrates the apparatus and equipments that were used during the water penetration and release experiments Figure C.1: Water purification system, Elga® PURELAB Flex Figure C.2: Analytical balance, AUW 120, Shimadzu 164 Figure C.3: UV-Vis spectrometer for nitrogen determination (U-2010, Hitachi) 165 ... DECLARATION OF THESIS Title of thesis Study the release of nitrogen from coated urea granule: Modelling and simulation TRINH HOAI THANH I _ hereby declare that the thesis...STATUS OF THESIS Title of thesis Study the release of nitrogen from coated urea granule: Modelling and simulation TRINH HOAI THANH I _ hereby allow my thesis... TEKNOLOGI PETRONAS STUDY THE RELEASE OF NITROGEN FROM COATED UREA GRANULE: MODELLING AND SIMULATION by TRINH HOAI THANH The undersigned certify that they have read, and recommend to the Postgraduate