Advanced Materials Research Vols. 383-390

Abstract: According to the analysis of heat balance, about 1/3 of the fuel combustion heat is taken away into the ambience by exhaust gas of diesel engine. Depending on the characteristics of the diesel, this paper uses a special system to recover this waste heat, in which the organic Rankine cycle is combined with a single screw expander. The economy should be improved by using this system in the diesel. The model of this system is designed in Matlab combined with REFPROP. Using this way, the thermodynamic parameters should be calculated and the thermodynamic properties of this system with different working fluids should be analyzed. At last, R245fa, R245ca, R123 and R141b are selected as the alternative refrigerants used in this system.

Abstract: An experimental study was conducted on a S.I. engine fueled by compressed natural gas and hydrogen blends (HCNG), in order to test different engine operating parameters that affect lean combustion limit (L.C.L) of HCNG engine. Firstly, constant ignition timing and ignition timing under maximum L.C.L (L.L.T) conditions were compared, then L.L.T conditions were adopted in this paper. The results indicated that for each condition, neither over-retarded nor over-advanced ignition timing are advised in order to achieve leaner combustion. L.C.L increases with hydrogen fraction in the blends, and slightly increases with throttle opening, while decreases when the engine speed is raised

Abstract: Heat sink does affect on the performance of thermoelectirc generator according to the studies of many authors. In this paper, an analytical model inculding the number of thermocouples and the thermal resistance of heat sink is derived. The match between the thermoelectric module and heat sink is discussed by numerical calculation also. The results show that the thermal resistance of thermoelectric module should be designed to match that of heat sink in order to get the highest output power for a given heat sink. But for a given thermoelectric module, the output power increases with the decrease of heat sink thermal resistance, and there is a suitable heat sink due to the limit of the temperature difference between the heat source and coolant.

Abstract: In this paper electronic control unit (ECU) used in vehicle-used compressed natural gas engine is developed independently. A series of start experiments are done with refitted JL465Q5 engine. Experimental monitoring system is developed as an interface connecting staff and single chip. Speed acquisition system is developed to record start process accurately in real time. The test results indicate that, more concentrated mixture is necessary when start speed is lower. Higher engine coolant temperature is conductive to cold start for natural gas engine. Multiple ignition control and ignition energy improvement is conductive to start successfully for natural gas engine. The results showed that electronic control unit (ECU) and speed acquisition system developed independently is practical and feasible.

Abstract: As the main heat exchanger for cooling tower, the performance of cooling tower packing will directly affect the cooling effect of the cooling tower. So it is important to develop the new cooling tower packing and test the performance. In this paper, the empirical formula of the new ramp-type packing was deduced based on an experimental study of packing performance. And the author analyse the factor affecting the number of transfer units(NTU) find that the NTU is not only related to gas-water ratio. According to the experimental study, the author deduced the new formula of the NTU and verified that the new formula of NTU is more accurate than the traditional formula Within a certain range of parameters.

Abstract: Based on the coal petrology character of Taixi anthracite, the selective flocculation-flotation preparation of super clean coal is studied. The influences factors of the type and dosage of dispersant, the type and dosage of flocculant, pulp density etc etc on its effect is analyzed, and, through the orthogonal experimental methods, the salience order, interaction, and the optimum combination of the main factors is revealed. The finally test results indicate that we can obtain an ash about 1.29% at a yield of 41.85%％ super clean coal, thus will provide basis for the future super clean coal industrialization.

Abstract: Bagasse alkali lignin is the primary constituent of pulping black liquor. The phenolic products such as phenol, 2,6-dimethoxy-phenol and 2-methoxy-phenol were obtained by catalytic liquefaction from bagasse alkali lignin, with the aim of enhancing its use value. In the investigation, under optimal conditions, using SiO2-Al2O3 or FeS as catalyst, the phenols yield reached 54.10% and 55.18%, respectively. HPLC spectrum showed that the phenolic products of them were different. FT-IR and H-NMR spectrums showed that, using SiO2-Al2O3 as the catalyst, the α-O-4 and β-O-4 ether bonds and C-Cα bonds of lignin units were prone to break, forming 2,6-dimethoxy-phenol, 2-methoxy-phenol and phenol. While FeS action was more difficult, the α-O-4 and β-O-4 ether bonds and Cα-Cβ bonds of lignin units broke down. Then, the introduction of additional hydroxyl groups from glycols consequently increased the final product solubility. At the same time, Cα–C bond of the phenylpropane linkage was broken to produce phenolic chemicals. Third, part of the phenylpropane linkage was prone to break Cα–Cβ bond and structural rearrangement occurred. So the content of 2-methoxy-4-methyl-phenol and the total yield of phenols were high.

Abstract: The purpose of the paper is to investigate propylene recovery by a new absorption system, namely water-in-oil emulsion absorbent. Water in oil emulsion, in which kerosene used as oil phase with dispersed water droplet, is prepared to be as absorbent to absorb propylene. The effect of volume fraction dispersed phase, dispersed droplet size, and the stirring rate on propylene absorption rate are researched. Experimental results indicate that the absorption rate of propylene can increase 20% compared with traditional absorption method. The volume fraction dispersed phase should be appropriate, otherwise the enhancement absorption can not be attained. The appropriate number is 0.05 for this dispersion. The smaller droplet size of dispersed phase as well as the faster stirring rate can increase the propylene absorption rate. The mechanism of enhancement propylene absorption is attributed to the intensive turbulence in boundary layer between gas and liquid due to the movement of dispersed water droplets.

Abstract: This paper presents a 3-phase, 7 kW, 3900 rpm, 4-pole, 12-slot interior permanent magnet (IPM) synchronous motor for machine tool applications. To reduce the torque pulsations of the initial designed motor, three small circular holes are drilled in the magnetic island, and the Taguchi parameter method coupled with the finite element method (FEM) analysis is employed to minimize the level of cogging torque, torque ripple and magnet volume of the motor. Results from the optimized motor demonstrate that the motor is favorable regarding cogging torque minimization, torque ripple minimization and magnet volume minimization

Abstract: Low-carbon plays an important role in world’s developments. More and more countries adopt clean energy to reach their emission reduction objectives. This article analyses China’s national photo-thermal application—based on present situation of solar water heater industry’s development in China, using growth model in curve estimation to predict national annual production and possessing capacity. It also compares China’s and other countries’ policies in supporting solar water heater industry, and puts forward advises about improving China’s national solar water heater industry’s policies.