Matanki okhazikika okhala ndi nsanja yathyathyathya a ma BEV ndi ma FCEV amagwiritsa ntchito zinthu zopangidwa ndi thermoplastic ndi thermoset zokhala ndi kapangidwe ka mafupa komwe kamapereka 25% yowonjezera ya H2. #hydrogen #trends
Pambuyo poti mgwirizano ndi BMW wasonyeza kuti thanki ya cubic ingapereke mphamvu zambiri kuposa ma cylinders ang'onoang'ono angapo, Technical University of Munich inayamba ntchito yopanga kapangidwe ka composite ndi njira yopangira yowonjezereka yopangira ma serial. Chithunzi chojambulidwa ndi: TU Dresden (pamwamba) kumanzere), Technical University of Munich, Department of Carbon Composites (LCC)
Magalimoto amagetsi a fuel cell (FCEVs) omwe amayendetsedwa ndi hydrogen yopanda mpweya (H2) amapereka njira zina zopezera malo osungira zachilengedwe. Galimoto yonyamula anthu ya fuel cell yokhala ndi injini ya H2 imatha kudzazidwa mu mphindi 5-7 ndipo imakhala ndi mtunda wa makilomita 500, koma pakadali pano ndi yokwera mtengo chifukwa cha kuchuluka kochepa kwa zinthu zomwe zimapangidwa. Njira imodzi yochepetsera ndalama ndikugwiritsa ntchito nsanja yokhazikika ya mitundu ya BEV ndi FCEV. Izi sizingatheke pakadali pano chifukwa matanki a cylindrical a Type 4 omwe amagwiritsidwa ntchito kusungira mpweya wopanikizika wa H2 (CGH2) pa 700 bar mu FCEVs sali oyenera zipinda za batri zomwe zapangidwa mosamala zamagalimoto amagetsi. Komabe, zotengera zopanikizika monga mapilo ndi ma cubes zimatha kulowa m'malo osungiramo zinthu athyathyathya awa.
Patent US5577630A ya "Chombo Chokakamiza Chophatikizana", pempho lomwe linaperekedwa ndi Thiokol Corp. mu 1995 (kumanzere) ndi chombo chokakamiza chamakona anayi chomwe chinali ndi patent ya BMW mu 2009 (kumanja).
Dipatimenti ya Carbon Composites (LCC) ya Technical University of Munich (TUM, Munich, Germany) ikugwira ntchito ziwiri zopanga lingaliro ili. Yoyamba ndi Polymers4Hydrogen (P4H), yotsogozedwa ndi Leoben Polymer Competence Center (PCCL, Leoben, Austria). Phukusi la ntchito la LCC limatsogozedwa ndi Fellow Elizabeth Glace.
Pulojekiti yachiwiri ndi Hydrogen Demonstration and Development Environment (HyDDen), komwe LCC imatsogozedwa ndi Wofufuza Christian Jaeger. Cholinga cha zonsezi ndikupanga chiwonetsero chachikulu cha njira yopangira thanki yoyenera ya CGH2 pogwiritsa ntchito zinthu zopangidwa ndi ulusi wa kaboni.
Pali mphamvu yochepa ya volumetric pamene ma silinda ang'onoang'ono a mainchesi aikidwa m'ma cell a batri athyathyathya (kumanzere) ndi zotengera za cubic type 2 zopanikizika zopangidwa ndi zitsulo ndi chipolopolo chakunja cha carbon fiber/epoxy composite (kumanja). Chithunzi Chochokera: Zithunzi 3 ndi 6 zachokera ku “Njira Yopangira Manambala ya Chotengera cha Bokosi Lopanikizika la Mtundu Wachiwiri chokhala ndi Miyendo Yamkati Yopsinjika” ndi Ruf ndi Zaremba et al.
P4H yapanga thanki yoyesera ya cube yomwe imagwiritsa ntchito chimango cha thermoplastic chokhala ndi zingwe zolimbitsa thupi zomangiriridwa mu epoxy yolimbikitsidwa ndi ulusi wa kaboni. HyDDen idzagwiritsa ntchito kapangidwe kofanana, koma idzagwiritsa ntchito automatic fiber layup (AFP) popanga matanki onse a thermoplastic composite.
Kuchokera pa pempho la patent la Thiokol Corp. mpaka "Chombo Choponderezedwa Chopangidwa ndi Composite Conformal" mu 1995 mpaka ku German Patent DE19749950C2 mu 1997, zombo za mpweya zopanikizika "zikhoza kukhala ndi mawonekedwe aliwonse a geometric", koma makamaka mawonekedwe athyathyathya komanso osasinthasintha, m'bowo lolumikizidwa ndi chithandizo cha chipolopolo. Zinthu zimagwiritsidwa ntchito kuti zizitha kupirira mphamvu ya kufalikira kwa mpweya.
Pepala la Lawrence Livermore National Laboratory (LLNL) la 2006 limafotokoza njira zitatu: chotengera cha pressure chopangidwa ndi filament, chotengera cha pressure cha microlattice chokhala ndi kapangidwe ka mkati ka orthorhombic lattice (maselo ang'onoang'ono a 2 cm kapena kuchepera), chozunguliridwa ndi chidebe cha H2 chokhala ndi makoma owonda, ndi chidebe chojambulira, chokhala ndi kapangidwe ka mkati kokhala ndi zigawo zazing'ono zomatidwa (monga mphete za pulasitiki za hexagonal) ndi kapangidwe ka khungu lopyapyala lakunja. Zidebe zobwerezabwereza ndizoyenera kwambiri pazidebe zazikulu komwe njira zachikhalidwe zingakhale zovuta kugwiritsa ntchito.
Patent DE102009057170A yomwe idaperekedwa ndi Volkswagen mu 2009 imafotokoza za chotengera chopanikizika choyikidwa pagalimoto chomwe chimapereka mphamvu zambiri komanso kukonza malo ogwiritsira ntchito. Matanki amakona anayi amagwiritsa ntchito zolumikizira zolimba pakati pa makoma awiri ozungulira, ndipo ngodya zake ndi zozungulira.
Malingaliro omwe ali pamwambawa ndi ena atchulidwa ndi Gleiss mu pepala lakuti “Kupanga Njira kwa Zombo Zopondereza za Cubic ndi Ma Stretch Bars” lolembedwa ndi Gleiss et al. ku ECCM20 (June 26-30, 2022, Lausanne, Switzerland). Munkhaniyi, akutchula kafukufuku wa TUM wofalitsidwa ndi Michael Roof ndi Sven Zaremba, womwe adapeza kuti chotengera cha cubic pressure chokhala ndi ma struts okakamiza olumikiza mbali zamakona anayi ndi chothandiza kwambiri kuposa masilinda angapo ang'onoang'ono omwe amalowa m'malo mwa batri yosalala, zomwe zimapereka malo osungira okwana pafupifupi 25%.
Malinga ndi Gleiss, vuto lokhazikitsa masilinda ang'onoang'ono ambiri amtundu wa 4 mu bokosi lathyathyathya ndilakuti "kuchuluka kwa masilinda pakati pa masilinda kumachepa kwambiri ndipo dongosololi lilinso ndi malo akuluakulu olowera mpweya wa H2. Ponseponse, dongosololi limapereka mphamvu zochepa zosungira kuposa ma cubic bottles."
Komabe, pali mavuto ena ndi kapangidwe ka thanki ya cubic. "Mwachionekere, chifukwa cha mpweya wopanikizika, muyenera kuthana ndi mphamvu zopindika pa makoma athyathyathya," adatero Gleiss. "Pa izi, mukufunikira kapangidwe kolimba komwe kamalumikizana mkati ndi makoma a thanki. Koma zimenezo n'zovuta kuchita ndi zinthu zopangidwa ndi composites."
Glace ndi gulu lake anayesa kuyika zitsulo zolimbitsa mphamvu mu chotengera chopanikizika m'njira yoyenera njira yozungulira ulusi. "Izi ndizofunikira popanga zinthu zambiri," akufotokoza, "ndipo zimatithandizanso kupanga mawonekedwe ozungulira a makoma a chidebe kuti tiwongolere bwino mawonekedwe a ulusi pa katundu aliyense m'derali."
Masitepe anayi opangira thanki yoyesera ya cubic composite ya pulojekiti ya P4H. Chithunzi chojambulidwa: “Kupanga njira yopangira zombo zopopera za cubic zokhala ndi cholumikizira”, Technical University of Munich, Polymers4Hydrogen project, ECCM20, June 2022.
Kuti akwaniritse unyolo, gululi lapanga lingaliro latsopano lokhala ndi masitepe anayi akuluakulu, monga momwe tawonetsera pamwambapa. Zingwe zomangirira, zomwe zikuwonetsedwa mumdima pamasitepe, ndi kapangidwe ka chimango chopangidwa kale pogwiritsa ntchito njira zochokera ku pulojekiti ya MAI Skelett. Pa pulojekitiyi, BMW idapanga "chimango" cha chimango cha galasi pogwiritsa ntchito ndodo zinayi zolimbikitsidwa ndi ulusi, zomwe kenako zidapangidwa kukhala chimango cha pulasitiki.
Chimango cha thanki yoyesera ya cubic. Zigawo za mafupa a hexagonal zosindikizidwa mu 3D ndi TUM pogwiritsa ntchito ulusi wa PLA wosalimbikitsidwa (pamwamba), kuyika ndodo za CF/PA6 pultrusion ngati zolumikizira zolimba (pakati) kenako ndikukulunga ulusi kuzungulira zolumikizira (pansi). Chithunzi chojambulidwa ndi: Technical University of Munich LCC.
“Lingaliro ndilakuti mutha kupanga chimango cha thanki ya cubic ngati kapangidwe ka modular,” anatero Glace. “Ma module awa amayikidwa mu chida chopangira umba, ma strut okakamiza amayikidwa mu ma module a chimango, kenako njira ya MAI Skelett imagwiritsidwa ntchito mozungulira ma strut kuti awaphatikize ndi zigawo za chimango.” njira yopangira zinthu zambiri, zomwe zimapangitsa kuti pakhale kapangidwe kamene kamagwiritsidwa ntchito ngati mandrel kapena pakati pokulunga chipolopolo cha thanki yosungiramo zinthu.
TUM idapanga chimango cha thanki ngati "khushoni" ya kiyubiki yokhala ndi mbali zolimba, ngodya zozungulira ndi mawonekedwe a hexagonal pamwamba ndi pansi pomwe ma tayi amatha kulowetsedwa ndikulumikizidwa. Mabowo a ma racks awa adasindikizidwanso mu 3D. "Pa thanki yathu yoyamba yoyesera, tidasindikiza magawo a hexagonal pogwiritsa ntchito polylactic acid [PLA, thermoplastic yochokera ku bio] chifukwa inali yosavuta komanso yotsika mtengo," adatero Glace.
Gululo linagula ndodo 68 zolimbikitsidwa ndi ulusi wa kaboni wa polyamide 6 (PA6) kuchokera ku SGL Carbon (Meitingen, Germany) kuti zigwiritsidwe ntchito ngati zomangira. "Pofuna kuyesa lingaliroli, sitinapange chilichonse chomangira," akutero Gleiss, "koma tinangoyika ma spacers mu chimango chapakati cha uchi chosindikizidwa cha 3D ndikuchimata ndi guluu wa epoxy. Kenako izi zimapereka mandrel yomangira thankiyo." Iye akunena kuti ngakhale ndodozi ndizosavuta kuzizungulira, pali mavuto ena akuluakulu omwe adzafotokozedwa pambuyo pake.
"Pa gawo loyamba, cholinga chathu chinali kusonyeza momwe kapangidwe kake kamagwirira ntchito ndikupeza mavuto mu lingaliro lopanga," anafotokoza Gleiss. "Chifukwa chake ma struts amatuluka kuchokera pamwamba pa chigoba, ndipo timalumikiza ulusi wa kaboni ku pakatikati pa izi pogwiritsa ntchito ulusi wonyowa. Pambuyo pake, mu gawo lachitatu, timapinda mutu wa ndodo iliyonse yomangira. Timangogwiritsa ntchito kutentha kuti tisinthe mawonekedwe a mutuwo kuti ukhale wosalala ndikutseka mu gawo loyamba la kukulunga. Kenako timapitiriza kukulunganso kapangidwe kake kuti mutu wathyathyathya ukhale wotsekedwa mkati mwa thanki. Timayika laminate pamakoma.
Chipewa chotchingira chopindika. TUM imagwiritsa ntchito zipewa zapulasitiki kumapeto kwa ndodo zomangirira kuti ulusi usasokonekere panthawi yopindika ulusi. Chithunzi chochokera kwa: Technical University of Munich LCC.
Glace anabwerezanso kuti thanki yoyamba iyi inali umboni wa lingaliro. "Kugwiritsa ntchito kusindikiza kwa 3D ndi guluu kunali kokha poyesa koyamba ndipo kunatipatsa lingaliro la mavuto ochepa omwe tidakumana nawo. Mwachitsanzo, panthawi yopindika, ulusi unagwidwa ndi malekezero a ndodo zomangika, zomwe zinapangitsa kuti ulusi usweke, ulusi uwonongeke, komanso kuchepetsa kuchuluka kwa ulusi kuti tithane ndi izi. Tinagwiritsa ntchito zipewa zingapo zapulasitiki ngati zothandizira popanga zomwe zidayikidwa pamitengo isanafike sitepe yoyamba yopindika. Kenako, pamene ma laminate amkati adapangidwa, tinachotsa zipewa zotetezazi ndikusintha malekezero a mitengo isanaphimbidwe komaliza."
Gululo linayesa njira zosiyanasiyana zokonzanso. "Amene amayang'ana mozungulira amagwira ntchito bwino kwambiri," akutero Grace. "Komanso, panthawi yopangira zitsanzo, tinagwiritsa ntchito chida chosinthira chowotcherera kuti tiike kutentha ndikusintha malekezero a tie rod. Mu lingaliro lopanga zinthu zambiri, mungakhale ndi chida chimodzi chachikulu chomwe chingapange ndikupanga malekezero onse a struts kukhala laminate yamkati nthawi imodzi."
Mitu ya Drawbar inasinthidwa mawonekedwe. TUM inayesa malingaliro osiyanasiyana ndipo inasintha ma weld kuti agwirizane ndi malekezero a zomangira zophatikizika kuti zigwirizane ndi laminate ya pakhoma la thanki. Chithunzi chojambulidwa: "Kupanga njira yopangira zombo zopondereza za cubic ndi brace", Technical University of Munich, Polymers4Hydrogen project, ECCM20, June 2022.
Motero, laminate imakonzedwa pambuyo pa sitepe yoyamba yozungulira, nsanamira zimasinthidwa mawonekedwe, TUM imamaliza kuzunguliza kwachiwiri kwa ulusi, kenako laminate yakunja ya khoma la thanki imakonzedwanso kachiwiri. Dziwani kuti iyi ndi kapangidwe ka thanki ya mtundu wa 5, zomwe zikutanthauza kuti ilibe chotchingira pulasitiki ngati chotchingira mpweya. Onani zokambirana mu gawo la Zotsatira Zotsatira pansipa.
"Tinadula chiwonetsero choyamba m'magawo osiyanasiyana ndipo tinajambula malo olumikizidwa," anatero Glace. "Kufufuza kwapafupi kukuwonetsa kuti tinali ndi mavuto ena ndi laminate, chifukwa mitu ya strut sinali yosalala pa laminate yamkati."
Kuthetsa mavuto okhala ndi mipata pakati pa laminate ya makoma amkati ndi akunja a thanki. Mutu wosinthidwa wa tie rod umapanga mpata pakati pa kuzungulira koyamba ndi kwachiwiri kwa thanki yoyesera. Chithunzi chojambulidwa ndi: Technical University of Munich LCC.
Thanki yoyamba iyi ya 450 x 290 x 80mm idamalizidwa chilimwe chatha. "Tapita patsogolo kwambiri kuyambira pamenepo, koma tikadali ndi kusiyana pakati pa laminate yamkati ndi yakunja," adatero Glace. "Chifukwa chake tidayesa kudzaza mipatayo ndi utomoni woyera komanso wokhuthala kwambiri. Izi zimathandizira kulumikizana pakati pa ma stud ndi laminate, zomwe zimawonjezera kwambiri kupsinjika kwa makina."
Gululo linapitiriza kupanga kapangidwe ndi njira ya thanki, kuphatikizapo mayankho a kapangidwe kozungulira komwe kumafunika. "Mbali za thanki yoyesera sizinali zopindika kwathunthu chifukwa zinali zovuta kuti mawonekedwe awa apange njira yozungulira," Glace anafotokoza. "Ngodya yathu yoyamba yozungulira inali 75°, koma tinkadziwa kuti ma circuit angapo amafunika kuti akwaniritse katundu mu chotengera chopanikizika ichi. Tikufunabe yankho la vutoli, koma sizophweka ndi mapulogalamu omwe alipo pamsika pakadali pano. Ikhoza kukhala ntchito yotsatira.
“Tasonyeza kuthekera kwa lingaliro lopangali,” akutero Gleiss, “koma tifunika kugwira ntchito molimbika kuti tiwongolere kulumikizana pakati pa laminate ndikusintha mawonekedwe a tie rods. “Kuyesa kwakunja pamakina oyesera. Mumakoka ma spacer kuchokera mu laminate ndikuyesa katundu wamakina womwe ma connection amenewo amatha kupirira.”
Gawo ili la polojekiti ya Polymers4Hydrogen lidzamalizidwa kumapeto kwa chaka cha 2023, pomwe Gleis akuyembekeza kumaliza thanki yachiwiri yowonetsera. Chosangalatsa n'chakuti, mapangidwe masiku ano amagwiritsa ntchito ma thermoplastics olimbikitsidwa bwino mu chimango ndi ma thermoset composites m'makoma a thanki. Kodi njira yosakanikirana iyi idzagwiritsidwa ntchito mu thanki yowonetsera yomaliza? "Inde," adatero Grace. "Ogwirizana nafe mu polojekiti ya Polymers4Hydrogen akupanga ma epoxy resins ndi zinthu zina zophatikizika zokhala ndi mphamvu zabwino zotchingira hydrogen." Amalemba anzawo awiri omwe akugwira ntchito pa ntchitoyi, PCCL ndi University of Tampere (Tampere, Finland).
Gleiss ndi gulu lake adasinthananso chidziwitso ndikukambirana malingaliro ndi Jaeger pa pulojekiti yachiwiri ya HyDDen kuchokera ku thanki ya LCC conformal composite.
"Tipanga chombo chopondereza cha conformal composite cha ma drone ofufuza," akutero Jaeger. "Ichi ndi mgwirizano pakati pa madipatimenti awiri a Dipatimenti ya Aerospace ndi Geodetic ya TUM - LCC ndi Dipatimenti ya Helikopita Technology (HT). Ntchitoyi idzatha pofika kumapeto kwa chaka cha 2024 ndipo pakadali pano tikumaliza chombo chopondereza. kapangidwe kake kamene kali ngati njira yoyendera ndege ndi magalimoto. Pambuyo pa gawo loyamba la lingaliro ili, gawo lotsatira ndikuchita chitsanzo chatsatanetsatane cha kapangidwe kake ndikuneneratu momwe khoma lidzagwirira ntchito."
“Lingaliro lonse ndi kupanga drone yofufuza yokhala ndi hybrid fuel cell ndi batire propulsion system,” iye anapitiriza. Idzagwiritsa ntchito batire panthawi yamagetsi amphamvu kwambiri (monga kunyamuka ndi kutera) kenako idzasinthira ku fuel cell panthawi yamagetsi opepuka. “Gulu la HT linali kale ndi drone yofufuza ndipo linasinthanso powertrain kuti igwiritse ntchito mabatire ndi ma fuel cell onse,” anatero Yeager. “Anagulanso thanki ya CGH2 kuti ayesere transmission iyi.”
“Gulu langa linapatsidwa ntchito yomanga chitsanzo cha thanki yothamanga chomwe chingagwirizane, koma osati chifukwa cha mavuto omangirira omwe thanki yozungulira ingapange,” iye akufotokoza. “Thanki yosalala sipereka kukana kwa mphepo kofanana. Kotero mumapeza magwiridwe antchito abwino paulendo.” Miyeso ya thankiyo ndi pafupifupi 830 x 350 x 173 mm.
Thanki yogwirizana ndi thermoplastic AFP. Pa pulojekiti ya HyDDen, gulu la LCC ku TUM poyamba linafufuza njira yofanana ndi yomwe Glace ankagwiritsa ntchito (pamwambapa), koma kenako linasintha njira pogwiritsa ntchito kuphatikiza ma module angapo omangira, omwe kenako anagwiritsidwa ntchito mopitirira muyeso pogwiritsa ntchito AFP (pansipa). Chithunzi chojambulidwa ndi: Technical University of Munich LCC.
“Lingaliro limodzi likufanana ndi njira ya Elisabeth [Gleiss],” akutero Yager, “yogwiritsa ntchito zida zolimbitsa thupi pakhoma la chotengera kuti zigwirizane ndi mphamvu zopindika kwambiri. Komabe, m'malo mogwiritsa ntchito njira yozungulira kuti tipange thanki, timagwiritsa ntchito AFP. Chifukwa chake, tinaganiza zopanga gawo lina la chotengera chopanikizika, momwe ma racks amalumikizidwa kale. Njira imeneyi yandithandiza kuphatikiza ma module angapo ophatikizidwawa kenako ndikuyika chivundikiro chomaliza kuti nditseke chilichonse AFP isanazungulire.”
"Tikuyesera kumaliza lingaliro lotere," adapitiliza, "ndiponso tikuyamba kuyesa kusankha zipangizo, zomwe ndizofunikira kwambiri kuti zitsimikizire kukana kofunikira kulowa kwa mpweya wa H2. Pachifukwa ichi, timagwiritsa ntchito kwambiri zipangizo za thermoplastic ndipo tikugwira ntchito zosiyanasiyana momwe zinthuzo zingakhudzire khalidwe la kulowa ndi kukonza kwa makina a AFP. Ndikofunikira kumvetsetsa ngati chithandizocho chidzakhala ndi zotsatirapo zake komanso ngati pakufunika kukonza pambuyo pake. Tikufunanso kudziwa ngati mikwingwirima yosiyanasiyana idzakhudza kulowa kwa haidrojeni kudzera mu chotengera chopanikizika."
Thankiyo idzapangidwa ndi thermoplastic yokha ndipo mizereyo idzaperekedwa ndi Teijin Carbon Europe GmbH (Wuppertal, Germany). "Tidzagwiritsa ntchito zipangizo zawo za PPS [polyphenylene sulfide], PEEK [polyether ketone] ndi LM PAEK [low melting polyaryl ketone]," adatero Yager. "Kenako kufananizidwa kumapangidwa kuti kuone kuti ndi iti yabwino kwambiri yotetezera kulowa mkati ndikupanga ziwalo zomwe zimagwira ntchito bwino." Akuyembekeza kumaliza kuyesa, kapangidwe kake ndi njira zoyendetsera zinthu komanso kuwonetsa koyamba mkati mwa chaka chamawa.
Ntchito yofufuzayi idachitika mkati mwa gawo la COMET “Polymers4Hydrogen” (ID 21647053) mkati mwa pulogalamu ya COMET ya Unduna wa Zakusintha kwa Nyengo, Chilengedwe, Mphamvu, Kuyenda, Kupanga Zinthu Mwatsopano ndi Ukadaulo ndi Unduna wa Zaukadaulo wa Digito ndi Zachuma wa Federal. . Olembawo akuthokoza ogwirizana nawo omwe adatenga nawo mbali Polymer Competence Center Leoben GmbH (PCCL, Austria), Montanuniversitaet Leoben (Faculty of Polymer Engineering and Science, Department of Chemistry of Polymer Materials, Department of Materials Science and Polymer Testing), University of Tampere (Faculty of Engineering Materials). ) Sayansi), Peak Technology ndi Faurecia adathandizira pantchito yofufuzayi. COMET-Modul imathandizidwa ndi boma la Austria ndi boma la boma la Styria.
Mapepala olimbikitsidwa kale a nyumba zonyamula katundu amakhala ndi ulusi wopitilira - osati wochokera kugalasi lokha, komanso kuchokera ku kaboni ndi aramid.
Pali njira zambiri zopangira zigawo zophatikizika. Chifukwa chake, kusankha njira ya gawo linalake kudzadalira zinthu zomwe zagwiritsidwa ntchito, kapangidwe ka gawolo, ndi momwe lidzagwiritsidwire ntchito kapena momwe lidzagwiritsidwire ntchito. Nayi kalozera wosankha.
Mabungwe a Shocker Composites ndi R&M International akupanga njira yobwezeretsanso ulusi wa kaboni womwe supereka kuphedwa konse, mtengo wotsika kuposa ulusi wa virgin ndipo pamapeto pake upereka kutalika komwe kumafanana ndi ulusi wopitilira mu kapangidwe kake.
Nthawi yotumizira: Marichi-15-2023