Abstract: This paper presents a small tube/wire type electrostatic precipitator (ESP). In the ESPs present form, particle charging and collecting voltages and airflow rates were individually varied throughout 200 ambient temperature test runs ranging from 10 to 30 kV in increments on 5 kV and 0.5 m/s to 1.5 m/s, respectively. It was repeatedly observed that, at input air velocities of between 0.5 and 0.9 m/s and voltage settings of 20 kV to 30 kV, the collection efficiency remained above 95%. The outcomes of preliminary tests at combustion flue temperatures are, at present, inconclusive although indications are that there is little or no drop in comparable performance during ideal test conditions. A limited set of similar tests was carried out during which the collecting electrode was grounded, having been disconnected from the static generator. The collecting efficiency fell significantly, and for that reason, this approach was not pursued further. The collecting efficiencies during ambient temperature tests were determined by mass balance between incoming and outgoing dry PM. The efficiencies of combustion temperature runs are determined by analysing the difference in opacity of the flue gas at inlet and outlet compared to a reference light source. In addition, an array of Leit tabs (carbon coated, electrically conductive adhesive discs) was placed at inlet and outlet for a number of four-day continuous ambient temperature runs. Analysis of the discs’ contamination was carried out using scanning electron microscopy and ImageJ computer software that confirmed collection efficiencies of over 99% which gave unequivocal support to all the previous tests. The average efficiency for these runs was 99.409%. Emissions collected from a woody biomass combustion unit, classified to a diameter of 100 µm, were used in all ambient temperature trials test runs apart from two which collected airborne dust from within the laboratory. Sawdust and wood pellets were chosen for laboratory and field combustion trials. Video recordings were made of three ambient temperature test runs in which the smoke from a wood smoke generator was drawn through the precipitator. Although these runs were visual indicators only, with no objective other than to display, they provided a strong argument for the device’s claimed efficiency, as no emissions were visible at exit when energised. The theoretical performance of ESPs, when applied to the geometry and configuration of the tested model, was compared to the actual performance and was shown to be in good agreement with it.
Abstract: The purpose of this project is to propose a quick and
environmentally friendly alternative to measure the quality of oils
used in food industry. There is evidence that repeated and
indiscriminate use of oils in food processing cause physicochemical
changes with formation of potentially toxic compounds that can
affect the health of consumers and cause organoleptic changes. In
order to assess the quality of oils, non-destructive optical techniques
such as Interferometry offer a rapid alternative to the use of reagents,
using only the interaction of light on the oil. Through this project, we
used interferograms of samples of oil placed under different heating
conditions to establish the changes in their quality. These
interferograms were obtained by means of a Mach-Zehnder
Interferometer using a beam of light from a HeNe laser of 10mW at
632.8nm. Each interferogram was captured, analyzed and measured
full width at half-maximum (FWHM) using the software from
Amcap and ImageJ. The total of FWHMs was organized in three
groups. It was observed that the average obtained from each of the
FWHMs of group A shows a behavior that is almost linear, therefore
it is probable that the exposure time is not relevant when the oil is
kept under constant temperature. Group B exhibits a slight
exponential model when temperature raises between 373 K and 393
K. Results of the t-Student show a probability of 95% (0.05) of the
existence of variation in the molecular composition of both samples.
Furthermore, we found a correlation between the Iodine Indexes
(Physicochemical Analysis) and the Interferograms (Optical
Analysis) of group C. Based on these results, this project highlights
the importance of the quality of the oils used in food industry and
shows how Interferometry can be a useful tool for this purpose.