RESUMO
The phenomenon of summer mortality in Pacific oysters cultures also occurs in Brazilian crops, with predominance in the adult phase, generating significant losses for local producers. In the search for a technological solution to mitigate its effects, the mechanical vapour compression and hydraulic refrigeration concepts are evaluated as two proposed cooling technologies. The comparative analysis carried out with numeric simulations indicated that the hydraulic cooling system presents disadvantages regarding both the size of the compression column and the energy efficiency, compared to the mechanical vapour compression cycle. By computing only the compression power, a COP value of 6.9 results for the MVCS at TCOND = 29.5 oC and TEVAP = 7.2 oC, while for HRS the COP value is around 3.1 for identical conditions. Results from the analysis contradict former publications, but are consistent with recent findings reported in literature.
Assuntos
Ostreidae , Refrigeração , Animais , Brasil , Temperatura Baixa , ÁguaRESUMO
The glow-to-arc transition phenomena (arcing) observed in plasma reactors used in materials processing was studied through the arcs characteristic current and voltage waveforms. In order to capture these arcs signals, a LABVIEW™ based automated instrumentation system (ARCVIEW) was developed, including the integration of an oscilloscope equipped with proper current and voltage probes. The system also allows capturing the process parameters at the arc occurrence moments, which were used to map the arcs events conditions. Experiments in H(2)-Ar DC pulsed plasma returned signals data from 215 arcs events, which were analyzed through software routines. According to the results, an anti-arcing system should react in the time order of few microseconds to prevent most of the damage caused by the undesired arcing phenomena.
