{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T15:00:32Z","timestamp":1785250832173,"version":"3.55.0"},"reference-count":27,"publisher":"American Chemical Society (ACS)","issue":"29","license":[{"start":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T00:00:00Z","timestamp":1784246400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,7,28]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>In the SCR systems of heavy-duty diesel engines, urea deposits formed under real operating conditions differ significantly from laboratory-prepared samples in morphology, composition, and structure. Under real operating conditions, the urea solution undergoes multiple dynamic deposition cycles, forming dense and compositionally complex stubborn deposits. Conventional laboratory methods\u2500such as single evaporation or single-layer liquid film models\u2500fail to replicate this process. To address this limitation, this study proposes a multilayer liquid-film heating crystallization method. The method is used to investigate the fundamental differences between crystallization on pre-existing crystal layers and static single-layer crystallization. Crystals derived from single-layer and multilayer liquid films of equivalent total thickness were analyzed using thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that (1) the first urea crystal layer in multilayer crystallization impedes heat transfer to the second liquid film, promoting the formation of lower-temperature crystal components; (2) multilayer urea crystals require higher temperatures for thermal decomposition compared to single-layer crystals; (3) when the temperature decreases (with the first layer\u2019s crystallization temperature being not lower than the heating temperature of the second layer), the crystal mass from multilayer crystallization exceeds that from single-layer crystallization of equivalent liquid film thickness; (4) multilayer crystallization, involving secondary deposition and a superimposed thermal history, facilitates the development of ordered columnar or layered microstructures with relatively clean surfaces.<\/jats:p>","DOI":"10.1021\/acsomega.6c02814","type":"journal-article","created":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T11:09:58Z","timestamp":1784286598000},"page":"43723-43734","source":"Crossref","is-referenced-by-count":0,"title":["Layer-by-Layer\nCrystallization Phenomena in Urea Solution:\nAn Experimental Study"],"prefix":"10.1021","volume":"11","author":[{"given":"Liwei","family":"Mao","sequence":"first","affiliation":[{"name":"Shanghai Dianji University , , ,","place":["shanghai, China, 201306"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-4245-2829","authenticated-orcid":true,"given":"Jialong","family":"Jiang","sequence":"additional","affiliation":[{"name":"Shanghai Dianji University , , ,","place":["shanghai, China, 201306"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bingqi","family":"Tian","sequence":"additional","affiliation":[{"name":"Shanghai Dianji University , , ,","place":["shanghai, China, 201306"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,7,17]]},"reference":[{"key":"2026072810115070000_cit1","doi-asserted-by":"publisher","first-page":"114025","DOI":"10.1088\/1748-9326\/aa8c84","article-title":"Potential\nreductions in ambient NO2 concentrations from meeting diesel vehicle\nemissions standards","volume":"12","author":"von Schneidemesser","year":"2017","journal-title":"Environ. 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Cent.\nSouth Univ."},{"key":"2026072810115070000_cit5","doi-asserted-by":"publisher","first-page":"1211","DOI":"10.1016\/j.applthermaleng.2016.09.134","article-title":"An experimental\nand numerical study on effects of exhaust gas temperature and flow\nrate on deposit formation in Urea-Selective Catalytic Reduction (SCR)\nsystem of modern automobiles","volume":"111","author":"Prabhu","year":"2017","journal-title":"Appl. Therm. Eng."},{"key":"2026072810115070000_cit6","doi-asserted-by":"publisher","first-page":"452","DOI":"10.3390\/catal9050452","article-title":"Research on Optimization\nDesign of SCR Nozzle for National VI Heavy Duty Diesel Engine","volume":"9","author":"Qian","year":"2019","journal-title":"Catalysts"},{"key":"2026072810115070000_cit7","doi-asserted-by":"publisher","first-page":"360","DOI":"10.1016\/j.jes.2024.06.022","article-title":"Development\nof the two-stage SCR control strategy to satisfy ultra-low NOx emission\nregulation for heavy-duty diesel engine","volume":"156","author":"Li","year":"2025","journal-title":"J.\nEnviron. Sci."},{"key":"2026072810115070000_cit8","doi-asserted-by":"publisher","first-page":"119855","DOI":"10.1016\/j.cej.2018.09.016","article-title":"Characterization of solid deposits\nfrom urea water\nsolution injected into a hot gas test rig","volume":"377","author":"Bo\u0308rnhorst","year":"2019","journal-title":"Chem.\nEng. J."},{"key":"2026072810115070000_cit9","doi-asserted-by":"publisher","first-page":"56711","DOI":"10.1007\/s11356-021-14057-4","article-title":"Effects\nof thermal treatments on\ncharacteristics and morphological variations in the deposits of urea-SCR\nsystems","volume":"28","author":"Prabhu","year":"2021","journal-title":"Environ. Sci. Pollut. Res."},{"key":"2026072810115070000_cit10","doi-asserted-by":"publisher","first-page":"144176","DOI":"10.1016\/j.cej.2023.144176","article-title":"Newly developed\ndetailed urea decomposition mechanism by marine engine\nurea-SCR system crystallization test and DFT calculations","volume":"470","author":"Xia","year":"2023","journal-title":"Chem. Eng. J."},{"key":"2026072810115070000_cit11","doi-asserted-by":"publisher","first-page":"128230","DOI":"10.1016\/j.cej.2020.128230","article-title":"Morphological characterization of urea derived deposits\nin SCR systems","volume":"409","author":"Ates","year":"2021","journal-title":"Chem. Eng. 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Sci."},{"key":"2026072810115070000_cit25","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1016\/j.ces.2013.11.013","article-title":"Kinetic modeling of urea decomposition\nbased on systematic thermogravimetric analyses of urea and its most\nimportant by-products","volume":"106","author":"Brack","year":"2014","journal-title":"Chem. Eng. 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