PERANCANGAN MESIN PENCETAK PELLET

Tujuan perancangan mesin pencetak pellet yaitu untuk mendapatkan desain dari mesin, mendapatkan gambar kerja kontruksi mesin, memperoleh data analisis teknik pada komponen transmisi mesin. Selain itu untuk menentukan hasil perhitungan harga pokok produk mesin pencetak pellet. Metode perancangan mesin ini mengacu pada konsep perancangan Pahl dan Beitz yaitu dengan beberapa tahapan, antara lain perencanaan dan penjelasan tugas, perencanaan konsep produk, pemberian bentuk pada produk, hingga menghasilkan detail desain berupa dokumen pembuatan produk (gambar kerja). Langkah yang dilakukan dalam proses perancangan mesin pencetak pellet ini adalah dengan perhitungan gaya yang terjadi pada mesin, daya motor yang dibutuhkan, pemilihan jenis transmisi, hingga menentukan bahan komponen yang dibutuhkan. Hasil perancangan adalah desain dan gambar kerja produk mesin pencetak pellet dengan dengan sumber penggerak motor listrik AC 0,25 HP. Diameter poros yang digunakan 25,4 mm dan 31,75 mm dari bahan ST-60. Mesin pencetak pellet ini memiliki konstruksi yang kuat dan ergonomis dengan spesifikasi mesin panjang 750 × lebar 550 × tinggi 890 mm. Taksiran harga jual mesin yang ditawarkan, yaitu senilai Rp 3.100.000,00

Calcium phosphate precipitation modeling in a pellet reactor

The calcium phosphate precipitation in a pellet reactor can be evaluated by two main parameters: the phosphate conversion ratio and the phosphate removal efficiency. The conversion ratio depends mainly on the pH. The pellet reactor efficiency depends not only on pH but also on the hydrodynamical conditions. An efficiency model based on a thermochemical precipitation approach and an orthokinetic aggregation model is presented. In this paper, the results show that optimal conditions for pellet reactor efficiency can be obtained

Contactless pellet fabrication

A small object is coated by holding it in the pressure well of an acoustic standing wave pattern, and then applying a mist of liquid coating material at low velocity into the pressure well. The pressure gradient within the well forces the mist particles to be pushed against the object. A lower frequency acoustic wave also can be applied to the coated object, to vibrate it so as to evenly distribute the coated material. The same lower frequency vibrations can be applied to an object in the shape of a hollow sphere, to center the inner and outer surfaces of the sphere while it remains suspended

Microstability analysis of pellet fuelled discharges in MAST

Reactor grade plasmas are likely to be fuelled by pellet injection. This technique transiently perturbs the profiles, driving the density profile hollow and flattening the edge temperature profile. After the pellet perturbation, the density and temperature profiles relax towards their quasi-steady-state shape. Microinstabilities influence plasma confinement and will play a role in determining the evolution of the profiles in pellet fuelled plasmas. In this paper we present the microstability analysis of pellet fuelled H-mode MAST plasmas. Taking advantage of the unique capabilities of the MAST Thomson scattering system and the possibility of synchronizing the eight lasers with the pellet injection, we were able to measure the evolution of the post-pellet electron density and temperature profiles with high temporal and spatial resolution. These profiles, together with ion temperature profiles measured using a charge exchange diagnostic, were used to produce equilibria suitable for microstability analysis of the equilibrium changes induced by pellet injection. This analysis, carried out using the local gyrokinetic code GS2, reveals that the microstability properties are extremely sensitive to the rapid and large transient excursions of the density and temperature profiles, which also change collisionality and beta e significantly in the region most strongly affected by the pellet ablation.Comment: 21 pages, 10 figures. This is an author-created, un-copyedited version of an article submitted for publication in Plasma Physics and Controlled Fusion. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

On the behavior of micro-spheres in a hydrogen pellet target

A pellet target produces micro-spheres of different materials, which are used as an internal target for nuclear and particle physics studies. We will describe the pellet hydrogen behavior by means of fluid dynamics and thermodynamics. In particular one aim is to theoretically understand the cooling effect in order to find an effective method to optimize the working conditions of a pellet target. During the droplet formation the evaporative cooling is best described by a multi-droplet diffusion-controlled model, while in vacuum, the evaporation follows the (revised) Hertz-Knudsen formula. Experimental observations compared with calculations clearly indicated the presence of supercooling, the effect of which is discussed as well.Comment: 22 pages, 8 figures (of which two are significantly compressed for easier download

The role of pellet thermal stability in reactor design for heterogeneously catalysed chemical reactions

For exothermic fluid-phase reactions, a reactor which is cooled at the wall can exhibit multiplicity or parametric sensitivity. Moreover, for heterogeneously catalysed exothermic fluid-phase reactions, each of the catalytically active pellets in the reactor can exhibit multiplicity. Both forms of multiplicity can lead to thermal instability and as such have to be taken into account in reactor design. Here the effect of both instabilities is quantified. To this end, simple first-order kinetics are assumed, and intraparticle resistances and reactor and particle dynamics are not considered. A one-dimensional model, consisting of microscale mass and heat balances, is chosen to describe the reactor. It is assumed that the fluid inlet temperature equals the coolant temperature. The pellet scale model is a combined mass and heat balance for the pellet and it assumes that the Chilton¿Colburn analogy holds. For its incorporation in the reactor model it is assumed that for every individual pellet heat removal to neighbouring pellets via the mutual contact spots is negligible as compared to the heat transferred to the surrounding fluid. Consequently every pellets is isolated from its neighbours. In the thermally most critical region, i.e. the hot-spot region, reactor stability is determined by three parameter groups: a dimensionless adiabatic temperature rise, an Arrhenius number or dimensionless activation temperature and the ratio of the number of heat transfer units to the number of reaction units. For pellet multiplicity, a fourth parameter group becomes significant in addition: the ratio of the reaction rate to the pellet mass transfer rate. This number depends on the pellet size. A general recipe is given which enables us to determine whether or not pellet thermal instability can become important in reactor operation. For the situation where it is significant, generalized diagrams are presented indicating which pellet sizes problems must be expected due to pellet multiplicity