Jet fuel refers to a form of aviation fuel, made up of a mixture of a great amount of various hydrocarbons, which is manufactured for use by aircrafts. It is crucial that the fuel used in a jet be of the required quality because contaminants can be detrimental not only to the engine, but also to people’s lives. Toxics in jet fuels include particulates or sediments, water, microbes, and surfactants. These contaminants can be infused into the fuel during manufacture and/or during handling at airports. Jet fuel quality control measures are carried out to ensure clean burning, high volumetric energy content and low temperature performance.
Data was obtained in order to examine the quality of jet fuel that was being used. The data collected included the jet fuel’s steam flow rate, the draw-off temperature, the top temperature, as well as the values for the flash point, the freezing point and the fuel’s density. The data was collected every day during the month of October 2010, at 0600 hours in the morning and then 1800 hours in the evening. Moreover, the daily production was recorded for all the days of the month. This provided the jet fuel’s specifications and production. The data was collected by use of random sampling, as random samples were obtained daily and used to determine and provide the needed values, that is, the jet fuel’s flash point, freezing point, density, steam flow rate, the draw off temperature and the top temperature. The total monthly count of data collected was sixty two because each day had two sets of data collected in the morning and in the evening for the whole month. The data was well recorded for analysis purposes.
The data was analyzed by use of Microsoft Excel software. This data that was collected and recorded was keyed into an excel spreadsheet so as to perform the required computations. First, graphs were drawn to show the behavior of the fuel. Using MS Excel, the graphs showing the variation of the flash points, the freeze points, the density and the daily productivity were produced. Since the data would be too long for the graphs, and to ease the complexity of the graphs, averages were obtained for daily values, and moreover, only odd numbered dates were used for the graphs.
Then statistical calculations were carried out. For the first three sets of data, that is, for the values of the freezing point, the flash point, and the fuel density, computations were performed to obtain the mean, the standard error, the median, the mode, the standard deviation, the minimum, the maximum, the sample variance, the skewness, the range, the kurtosis, and the sum. These computations were done for both the morning set of data, the evening set of data and for the all the samples combined. The standard deviation represents a measure of the distribution of numbers or values. The standard deviation was found out by calculating the square root of the variance. The standard deviation was significant in indicating how varying the data obtained was from the determined mean value.
Following the determination of these statistical values, the confidence interval was estimated for the samples of: a freeze point, a flash point and the density. Two methods were used in determining the confidence levels, the first involving the actual determination of the average and the standard deviation, and the second method requiring an assumption of the standard deviation using an approximate normal distribution of the population from which the data was drawn. Consequently, the hypotheses testing of the data was conducted to determine how probable the data collected was and if it was sufficient enough to make a conclusion. Two regression analyses were used to model and analyze the variables of flash point versus the stripping steam and the variables of the freezing point versus the draw off temperature.
Results and Conclusion
The graphs obtained showed the daily variation of the jet fuel’s flash point, freeze point and its density. The density was found to register the least daily variation, and this deduction is supported by the standard deviation which was found to be less than 0.0003. The jet fuel’s production was also rather consistent, except that there was a considerable drop towards the end of the month. The mean values for the all samples of the jet fuel’s flash point, freeze point and density were 40, -48 and 0.79 respectively. The collected data registered very high confidence levels of 98% and the rejection of the null hypothesis implied that the data obtained had enough statistical significance that could make the necessary conclusions.
The high flash point obtained showed that the jet fuel was of a high quality that could withstand the heat and stress during high speed flights. While the fuel has the required density, it is important that it remains well drained to avoid problems with freezing and microbial growth. However, the low freezing point of the jet fuel will ensure that at high altitudes, ice crystals would not be formed and clog system components or fuel lines, interfering with the fuel supply to the engine. Sufficient fuel velocity is also crucial in prevention of the accumulation of sediments or particulates.