Impingement heating in which the flame jet impinges directly on the heating object has wide industrial and domestic application. In the Chinese community, impingement heat is used for cooking at home and in the restaurants.

There are two basic types of flame jets: premixed and non-premixed (diffusion). The flame to be investigated in this project is called inverse diffusion flame (IDF), which comprised of a central air jet surrounded by fuel port(s). There are very few investigations on IDF and almost none on impingement heating. However, IDF has a wider range of stable operation than premixed flame and is less sooty than diffusion flame. It also has potential for low NOx emission. Hence, it has good potential for application in impingement heating for better thermal performance and lower emissions.

This project will provide information for the design of IDF burners for impingement heating. It will contribute to the scientific and technological development of burners.

Project 2: Development of diesel engine with diesel/methanol compound combustion

Methanol is an alternative clean fuel. It is easily available, has no fuelling problem and is at a lower cost than diesel fuel. If methanol can be burned on existing diesel engines, it will help to reduce reliance on fossil fuel, reduce operating cost of vehicle users, and reduce particulate and nitrogen oxides emissions.
This project is concerned with the application of a diesel/methanol compound combustion technology to in service diesel engines for simultaneous reduction of particulate and nitrogen oxides emissions. With the compound combustion technology, methanol will be injected into the manifold to form a homogeneous mixture with air for combustion, while the original diesel fuel injection system will be retained but slightly modified to limit diesel fuel injection. At engine start and light loads, the engine will operate on diesel alone. At medium to high loads, the engine will operate on a homogeneous air/methanol mixture ignited by pilot diesel. This project aims to investigate the diesel/methanol injections under different engine operating conditions to achieve ultra low emissions.

Project 3: Influence of biodiesel on physical and chemical properties of particulate matter emitted from a diesel engine

Biodiesel has been blended with diesel fuel for application to diesel vehicles for reducing diesel fuel consumption, CO2 emissions and air pollution. The amount of biodiesel that is allowed in the blended fuel has been increasing.

Particulate matter originating from vehicle emissions has been linked to a myriad of adverse health outcomes, ranging from cancer to cardiopulmonary disease, and an array of environmental problems, including global warming and acid rain. The physical and chemical properties of particulate emissions determine their potential influence on the environment and human health. It is known that the use of biodiesel as a blended fuel may lead to a change in both the physical and chemical properties of the particulate. However, there is lack of detailed investigations on these changes.

Experiments will be carried out on a 4-cylinder diesel engine which is commonly found on diesel trucks in Hong Kong and in the mainland China. The engine will be tested under different engine operating conditions. At each engine operating condition, the exhaust particulate and co-pollutants will be collected and measured to analyze their physical and chemical properties. The physical properties to be investigated include the size of the primary soot particles, the shape of the agglomerated particles and the nanostructure of the soot particles, as observed under the transmission electronic microscope. On the chemical side, the fraction of volatile substance adsorbed by the particulate, the black carbon content of the particulate, the organic and inorganic compounds in the particulate will be analyzed using different analytical instruments. The amount of particle bound black carbon in the atmosphere can effectively absorb solar radiation thus affecting the energy redistribution and global climate. The organic compounds include carcinogenic polycyclic aromatic hydrocarbons (PAHs) etc. To link engine exhaust with health effect, this investigation will also include analysis of the oxidative potential of the particulate through the generation of reactive oxygen species (ROS) on cellular level. It is known that ROS are essential intermediates in metabolism with powerful oxidative potential, and are known to be capable of resulting in the oxidative damages.

This project provides information and scientific knowledge on the potential impact of biodiesel on the physical, chemical and toxicological properties of the particulate emitted by a diesel engine using biodiesel/diesel blended fuel, which are important for assessing the subsequent influence on our environment and human health. mation is important but is currently not available.