New alternative jet fuels have provided many advantages in the aviation industry, especially in terms of economics and environment. However, fuel–seal compatibility is one of the major issues that restricts alternative fuel advancement into the market. Thus, to help understand and solve the problem, this study examines the swelling effect of prepared and non-prepared O-rings in different fuels and aromatic species. Stress relaxation experiments were carried out to evaluate seal compatibility under compression, which mimics engine operation conditions. Seals were compressed and immersed in a variety of fuels and their blends for about 90h while maintaining a constant temperature 30°C and constant compression force of 25% seal thickness. The two types of elastomers investigated were fluorosilicone and nitrile O-rings, which are predominantly used in the aviation industry. Meanwhile, three different fuels and aromatic species were utilised as the variables in the experiments. The fuels used were Jet-A1, SPK and SHJFCS, while the aromatic species added were propyl benzene, tetralin and p-xylene. The swelling effects were determined from the P/Po value. Results indicate that Jet-A1 has the highest swelling effect, followed by SHJFCS and SPK. It was observed that the higher the percentage of aromatics in fuel, the higher the rate of swelling. Furthermore, prepared seals had a lower swelling rate than did non-prepared seals. Meanwhile, the intensity of the swelling effect in the Jet-A1-SHJFCS blends was in the order of 60/40, 85/15 and 50/50 blend. The work done in this study will aid in the selection of suitable aromatic species in future fuels. The novelty of this research lies in the determination of the appropriate amount of aromatic content as well as the selection of type of aromatic and its mixture fuel. Moreover, the various proportions of fuel blends with aromatic are investigated. The primary aim of this study is to understand the behaviour of prepared and non-prepared seals, and their compatibility with alternative fuels.

The importance of fuel injection methods and their atomisation characteristics has been well described in literature. Also, there are a large number of studies in literature detailing the impact of bulk properties of conventional fuels on atomisation and spray characteristics. However, there is a lack of knowledge on how different alternative fuels, and specifically aromatic species, impact spray and atomisation characteristics. In this investigation, the impact of alternative fuels, selected aromatic species and their properties on spray atomisation was studied. Details of how different aromatic structures, bonds and other micro properties of aromatics species impact spray and atomisation characteristics were investigated. To achieve this objective, testing was conducted using a Rolls-Royce Tay engine fuel injector. It was found that the droplet sizes in the form of the Sauter Mean Diameter (SMD) correlate well with fuel properties including density, viscosity and surface tension, which is in line with other published literature. Moreover, it was found that there are several aromatic species (ethylbenzene, cumene and tert-butylbenzene) which display improved atomisation. This indicates that the size of the aliphatic groups attached to the benzene ring in the aromatic molecule impact on the drop size and thereby the combustion characteristics. The worst performers were polyaromatic naphthalene compounds. With the increasing push for fuels with selected aromatic species in the future, this study provides knowledge on the impact of their on the atomisation characteristics.

Peanuts are not often used as a true oilseed crop, especially for the production of fuel. However, peanut could be a feedstock for biodiesel, especially in on-farm or small cooperative businesses, where producers can dictate the cost of making their own fuel. Field studies were conducted in 2005 and 2006 to assess low-cost weed-control systems for peanuts that would facilitate the economic viability of peanut biodiesel. Four preselected herbicide costs ranging from $25 to $62/ha and two application timings were compared with nontreated ($0/ha) and typical ($115/ha) herbicide programs for weed control and peanut oil yield. A peanut oil yield goal of 930 L/ha was exceeded with multiple low-cost herbicide systems in 3 of 4 site–yr. The main effect of application timing was only significant for a single site–year in which oil yield increased linearly with cost of the PRE and POST weed-control system. An herbicide cost of $50/ha, using PRE and POST applications, was consistently among the highest in oil yield, regardless of site–year, exceeding the typical (high value) programs in 3 of 4 site–yr. Use of reduced rates of imazapic (0.5× or 0.035 kg ai/ha) was detrimental in 2 of 4 site–yr. Weed control, and thus oil yields, were most dependent on species present at each location and not on input price. Data from this series of studies will allow researchers and entrepreneurs to more accurately assess the viability and sustainability of peanut biodiesel.