Yaodong Wang

Experimental investigation of applying miller cycle to reduce NOx emission from diesel engine

Abstract An experimental investigation of nitrogen oxides (NOx) emission reduction from a diesel engine using the Miller cycle was carried out. A Lister-Petter diesel engine, type TS2, was used for the experiments. Three versions of Miller cycles were designed and realized on a diesel engine. A series of tests were carried out on the test rig to compare the performances and emissions of the original engine (standard dual cycle) with those of the three versions of Miller cycles. The test results from the standard dual cycle and from the three versions of Miller cycles showed that applying Miller cycle to the diesel engine could reduce the NOx emission from the diesel engine. The reduction ratios of NOx for the Miller cycles are from 4.4 to 17.5 per cent. The best reduction effect is Miller cycle 1 and the reduction rates of NOx are from 11.0 to 17.5 per cent.

An equivalent circuit grid model for no-insulation HTS pancake coils

An equivalent circuit grid (ECG) model is proposed to analyse the time-varying characteristics of no-insulation (NI) ReBCO pancake coils. In the model, each turn of the coil is subdivided into fine elements in the azimuthal direction, and each element is equivalent to a circuit parameter. Then, the coil is equivalent to a circuit grid. A math model based on Kirchhoffs law is proposed to solve the circuit grid model. The distribution of the electrical current inside the NI coil is analysed for the charging and discharging process. A finite element method (FEM) model is coupled to calculate the magnetic field induced by the coil. To validate the model, a double pancake (DP) coil is fabricated by coated conductor ReBCO tapes. Charging and discharging tests are performed on the coil at 77 K. The results from simulations and experiments exhibit a good agreement. Then, this model is used for more studies on the current distribution inside the NI coil in the charging and discharging process. The charging and discharging delay of NI coil is analysed and explained by the model. The model can also be applied to partial insulated (PI) coils and magnets consisting of NI coils.

Waste biomass from production process co-firing with coal in a steam boiler to reduce fossil fuel consumption: A case study

Abstract Waste biomass is always generated during the production process in industries. The ordinary way to get rid of the waste biomass is to send them to landfill or burn it in the open field. The waste may potentially be used for co-firing with coal to save fossil fuel consumption and also reduce net carbon emissions. In this case study, the bio-waste from a Nicotiana Tabacum (NT) pre-treatment plant is used as the biomass to co-fire with coal. The samples of NT wastes were analysed. It was found that the wastes were of the relatively high energy content which were suitable for co-firing with coal. To investigate the potential and benefits for adding NT wastes to a Fluidised Bed Combustion (FBC) boiler in the plant, detailed modelling and simulation are carried out using the European Coal Liquefaction Process Simulation and Evaluation (ECLIPSE) process simulation package. The feedstock blending ratios of NT waste to coal studied in this work are varied from 0% to 30%. The results show that the addition of NT wastes may decrease the emissions of CO 2 and SO x without reducing the boiler performance.

Study on a Numerical Method for Calculating the Heating Process of HTS DC Induction Heater

A commercial HTS dc induction heater for aluminium billets is going to be built in Shanghai Jiao Tong University, China. To achieve an optimal design, a numerical model is proposed to accurately calculate the heating process of the billets due to induced current. The model is based on two physics fields i.e. including thermodynamics and electromagnetism. The changes of relevant parameters with increase of billets temperature are taken into account. In the model, the billets rotate in a dc magnetic field generated by a HTS magnet with iron cores. The induction heating power and temperature distribution inside the billets can be calculated accurately. In order to validate the calculation, a small laboratory-scale prototype dc inductive heater for aluminium billets is built. The coils are immersed in liquid nitrogen to flow higher current, and the billet is rotated by a motor. Comparison is carried out on the results of numerical model and experiment and analysis is made for the discrepancy between them. The discrepancy is acceptable for engineering applications. Finally, some examples of using the numerical model to calculate the electromagnetic behaviour for a commercial industry-scale dc induction heater are given.

Fabrication and Characteristic Tests of a Novel Low-Resistance Joint Structure for YBCO Coated-Conductors

Joints play an important role in the application of YBaCuO-coated conductors. Given the limited length and various requirements of tapes, large numbers of joints are needed in some applications. Therefore, developing stable joints between tapes and achieving low joint resistance has become an important issue for the application of YBCO tapes. In this paper, we propose a novel superconducting joint production process and fabricate these joints with a lamination machine. A few meters or more than 10 m of joint overlapping length can be achieved, and the joint resistance can be as low as 2.25 nΩ when the overlapping length reaches 8 m. A series of experiments has been carried out to explore the joint resistance changing law, with overlap length increases, and the joint characteristics. The results show that joint resistance is inversely proportional to the overlap length. Although long bridge joints cost more, they have an incomparable advantage in that the joint resistance is distributed over the bridge joint, which allows for more stable operation and less liquid nitrogen boiloff. After joint lamination processing, the burnout current rises from 276 to 523 A. Critical current and joint resistance are not affected by the overcurrent before the joint burns out.

Characteristics of a diffusion absorption refrigerator driven by the waste heat from engine exhaust

Abstract The characteristics of a diffusion absorption refrigerator driven by the waste heat from a diesel engine exhaust were investigated. The heating unit of the diffusion absorption refrigerator was modified to be able to utilize the waste heat from engine exhaust. A series of tests were conducted including the original refrigerator driven by the alternating current (AC) power, direct current (DC) power, liquid petroleum gas (LPG), and the waste heat from a diesel engine exhaust gas. The performances of the modified refrigerator driven by the waste heat from engine exhaust were compared with that of original performances of the refrigerator driven by AC, DC, and LPG. The results showed that the performances of the refrigerator driven by engine exhaust were better than that of the original refrigerator driven by AC and DC power. The results showed that the exhaust heat from diesel engine is an applicable, attractive energy resource for diffusion absorption refrigerator.

An Experimental Investigation of NOx Emission Reduction From Automotive Engine Using the Miller Cycle

An experimental investigation of NOx emission reduction from automotive (petrol) engine using the Miller Cycle was carried out. Two versions of Miller Cycle were designed and realized on a petrol engine. The tests were carried out on the test rig. The test results showed that applying Miller Cycle could reduce the emission of nitrogen oxides from petrol engine.Copyright

A Theoretical and an Experimental Investigation of a Small Scale Trigeneration System: A Comparison Between Trigeneration and Separate Generation Systems

A theoretical and an experimental investigation of a small scale trigeneration based on a diesel engine generator set is conducted. Comparing with the separate generation system, trigeneration saves primary energy input; and it reduces CO2 gas emission to the environment. A conclusion can be drawn that trigeneration is an environment friendly method, and it is financially feasible.Copyright

Heating Characteristics of a HTS DC Induction Heater for Aluminum Billets

The heating process of aluminum billets requires controllable temperature distributions and high efficiency. Compared with conventional ac induction heaters, the high temperature superconductor (HTS) dc induction heater has advantages of energy saving and better heating quality. In this paper, a HTS magnet is designed to achieve controllable temperature distribution for dc induction heater. A C-shaped iron yoke is used to separate HTS coils and billets. An aluminum billet is rotated in the air gap of the C-shaped magnet. Magnetic field distribution can be changed through adjusting width of the air gap. Therefore, the temperature gradient in axial direction is controllable. A dc induction heater prototype using this design is fabricated and its heating characteristics are tested. A numerical model is built to simulate heating process and temperature distributions of aluminum billet. Various uniform and gradient temperature distributions of a billet are measured and compared with numerical results.

Insulation Characteristics of Polyimide as Insulation Material Used in Pancake Tape Coil Structure for Resistive-Type SFCL

Space utilization is very important for the application of a superconducting fault current limiter (SFCL) in a high-voltage power system. Accordingly, for efficient space utilization, a pancake structure in which superconducting tapes are wound into coils should be adopted. However, because neighboring windings are in direct contact with each other in a pancake structure, special measures must be taken to overcome high-voltage insulation safety problems. This paper proposes two methods: 1) lapping polyimide adhesive tapes on superconducting tapes; and 2) coating a very thin layer of polyimide on the surface of superconducting tapes. A comparison is made between the two methods. A special breakdown strength testing platform is manufactured. Using the platform, the breakdown strength and surface flashover voltage are tested. Considering that the edges of superconducting tapes are very sharp, the influence of pre-breakdown partial discharge on insulation is explored. The results will be used to design and optimize the geometrical structure of the SFCL pancake component.