Advanced Materials Research Vols. 953-954

Abstract: It presents a new idea of producing methane with solar heating. In order to improve the temperature and promote production of methane, providing the run situation of solar digesters on every stage with the heat-transfer content and the temperature of digesters is shown in this article. It indicates that in this experimental study, according to processing and analysis the experimental data, it’s beneficial to improve the rates of biogas production, and it solve the problem of digester and safe operation in winter in the northeast of China.

Abstract: In winter,Many families use air source heat pump because of the low evaporation temperature of the system, resulting in lower heating efficiency of system. To solve this problem, the low temperature solar assisted hot water was added to the project which is on the basis of air source heat pump, and the system has been tested. After analysis of the collection efficiency of solar collectors at low temperatures and comparative analysis of the temperature cycle, pressure, energy consumption of the low-temperature solar-assisted systems and air source heat pump system, the optimal collector temperature and law of heat pump refrigerant cycle changes of the system were obtained. Theoretically, comparative analysis of low temperature air source heat pumps and solar hot water secondary air source heat pump compression ratio and COP. It gives the key parameters affecting the compression ratio and COP, pointing out ways to improve the heat pump COP. Finally, a key measure to improve the thermal performance of the unit system is proposed, to provide a reference for future practical applications and research. Foreword Air source heat pump in ambient air contains rich low grade solar potential as a source of heat, it has inexhaustible characteristics [1] . The main reason for restricting the use of air source heat pump in northern area of our country is when the outdoor air temperature is low in winter, the outdoor coil frost severe heating efficiency air source heat pump is greatly reduced. Martinez suggested experimental study on the application of solar radiant floor heating systems , solar water temperature is 50-60°C, low efficiency, especially when overcast snow lower system efficiency [2] .In view of the outdoor coil frosting problem, direct expansion solar assisted heat pump water heater system using the proposed by Li Yuwu, from a certain extent alleviated the problem of heat in winter for coil winter fros, improving the heating coefficient and improved the operating characteristics of the unit. However, this system requires the direct absorption of heat in air tube, and the specific heat of air is small, difficult to heat storage, illumination by solar radiation impact, unstable system operation [3]. Based on the above issues, for the low-level office building , the new rural residential , this study presents low temperature solar auxiliary air source heat pump system , the device uses low-temperature solar hot water heat pump system as low , both full use of solar energy , but also eliminates the original system frost problems and improve the efficiency of solar collectors and heat set to improve the evaporation temperature of the evaporator , thereby increasing the compression ratio of the heat pump unit .

Abstract: A novel MPPT control strategy with only sampling the port voltage of the solar cell is presented in this paper. The principle of the MPPT system is analyzed and the criterion to reach the maximum power point is deduced. Based on the obtained criterion, a novel algorithm realizing MPPT is proposed. The feasibility of the proposed control strategy and the correctness of the theoretical analysis are verified by the experimental results.

Abstract: Biological fuels have triggered the heated controversy in recent years. This paper critically examined the potentials of biological fuels through the lens of Multi-Criteria Analysis (MCA) and Integrated Conservation and Development Projects (ICDP). Although MCA framework may possess the capability in making the right decision on land diversion to handle the intensifying competition for land between biofuels and food production, it is difficult to reach a balance among sufficient biofuels supply, biodiversity conservation and social equity from the perspective of ICDP. Despite biofuels could not totally displace fossil fuels in the near future, there might still be some possible policy designs that can help realizing the smooth transition to the biofuels era.

Abstract: Microbial fuel cell (MFC) represents a new method for simultaneously swine wastewater treatment and electricity generation. However, few studies revealed the high electricity generation and pollutant removal using a large-scale single-chambered MFC in treating swine wastewater. Results indicated optimal hydraulic retention time (HRT) of swine wastewater was 8 d considering the removal efficiency and the power density. Under this condition, this MFC system removed 85.62% TCOD and 73.6% NH₃ as well as achieved power density of 368 mW/m². Results also showed the maximum power density of the MFC was 382.5±10.6 mW/m² MFC at 350 Ω. TCOD concentration in the swine wastewater was limiting factor for power output. The maximum power density was P_max= 385 mW/m², with a half-saturation concentration of Ks=2,050 mg/l. To our knowledge, this is the first time to demonstrate the electricity characteristics of a large-scale single-chambered MFC in treating swine wastewater.

Abstract: The aim of this work was to investigate the acid inhibition during the anaerobic digestion of municipal solid waste. Four biodegradable substrates of soybean, fat meat, rice and celery cane were considered in this paper. A series of anaerobic co-digestion tests were performed on the four substrates at the load of 1.0gVS/(L•d) and anaerobic granular sludge. The method to calculate the lowest acidification points of the four substrates was provided by the least squares method, and it is verified by the measured data, and good agreements are achieved.

Abstract: The objective of this research was to determine the application effects of compost produced from tree pruning waste and cow dung amended with biomass fly ash on soil acidity neutralization and Chinese cabbage growth. The acid soils were mixed with six different composts and fly ash, namely, Run 16: soil+composts produced from tree pruning waste, cow dung amended with fly ash ranged from 0% (control) to 4%, 8%, and 12%; Run 5: soil+control compost+fresh fly ash; and Run 6: soil+fresh fly ash. Thereafter, they were cured and placed in ten replicated diameter pots for growing Chinese cabbage (Brassica chinensis var. parachinensis). The composite samples of soils during curing and planting were taken and analyzed for their pH, exchangeable hydrogen, and aluminum ions. The height and weight of each vegetable were determined. The results showed that both fly ash and compost can neutralize the acid soil and decrease the quantity of exchangeable hydrogen and aluminum ions. The maximum growth of the Chinese cabbage was found in the soil mixed with the compost produced from compost mixes amended with 8% fly ash.

Abstract: Enzymatic hydrolysis lignin was prepared and used to converse into aromatic aldehydes by catalytic wet oxidation with activation of Fenton reagent. The results demonstrated that the enzymatic hydrolysis lignin was a suitable raw material for the preparation of aromatic aldehydes. Orthogonal experiments were conducted to obtain the optimum preparation conditions. The effects of activation time, activation temperature, ratio of liquid to solid and pH of the reaction system on the yield of aromatic aldehydes were dealt with in this paper and optimal activation conditions were obtained as followed: the pH of activating reaction system was 4, activation temperature was 60°C, ratio of liquid to solid was 20:1 and activation time was 30 min. The highest yield of 13.74 % was obtained under the optimum conditions.

Abstract: Three kinds of carbon-based solid acid catalysts were prepared to hydrolyze cellulose with activated carbon (AC) and multi-walled carbon nanotubes (MWCNTs) as the carrier. The prepared solid acid catalysts were characterized by BET, SEM, XRD, FTIR and TG analysis. The catalytic activities of these prepared solid acid catalysts for heterogeneously catalyzed hydrolysis of microcrystalline cellulose were further investigated. The catalysts bearing hydroxyl, carboxyl and sulfonic groups is thermally stable. Due to the amorphous multi-layered structure and the large number of defected structure, AC-based solid acid bears more acid groups than the MWCNTs-based catalyst. which hence showing higher activity for the catalytic hydrolysis of cellulose. AC-based solid acid exihibited two-fold higher catalytic efficiency than that of the MWCNTs-based solid acid catalysts.

Abstract: The compositions and crystallization process at low temperature of palm-based biodiesel (PME) are investigated. In this work, we show that PME is mainly composed of fatty acid methyl esters of 14-24 even-numbered C atoms: C_14:0-C_24:0, C_16:1-C_22:1, C_18:2, and C_18:3. Palm-based biodiesel crystallization comprises three steps, viz., forming supersaturated solution, nucleation and ester crystal growth; the driving force for saturated fatty acid methyl esters nucleation is the degree of supersaturation. The rate equation of nucleation is put forward. The objective of this research is to provide theoretical support for hindering the ester crystal nucleation and growth, and improving the cold flow properties of PME.