Following　the　massive　consumption　of　traditional　fossil　fuels,　the　technology　of　concentrating　solar　power　embedded　with　energy　storage　is　becoming　more　and　more　attractive.　Within　this　new　trend,　ammonia-based　thermochemical　energy　storage　is　prospectively　promising.　The　aim　of　this　study　is　to　simulate　the　ammonia　decomposition　reaction　in　a　tubular　reactor　fully　packed　with　homogeneously　isotropic　catalyst　particles.　Ignoring　the　radial　heat　conduction　and　pressure　drop,　a　one-dimensional　thermodynamic　mathematical　model　is　established　to　simulate　ammonia　conversion　accounting　for　operating　pressure　and　temperature,　solar　flux　distribution,　and　geometric　structure.　It　is　concluded　from　the　simulation　results　that　the　effect　of　the　operating　temperature　on　ammonia　conversion　is　more　predominant　than　the　effect　of　the　operating　pressure.　Furthermore,　for　the　four　styles　of　solar　flux　distribution,　the　distribution　with　the　lowest　effective　deviation　is　the　most　suitable　style　for　ammonia　decomposition,　and　the　efficiency　is　improved　about　15%　compared　with　σ=0.5.　Regarding　the　geometric　structure,　the　conversion　rate　progressively　increases　with　diameter　and　length　of　the　tubular　reactor,　and　an　optimization　formula　is　subsequently　proposed　for　geometric　design.　Ultimately,　the　design　and　optimization　criterion　for　the　tubular　reactor　are　presented.　©　2020　American　Society　of　Civil　Engineers.