Experimental investigation on the hybrid system of mechanical vapor recompression and hollow fiber vacuum membrane distillation applied for wastewater treatment.

In order to achieve zero discharge and resource utilization of industrial high salt wastewater, a hybrid system of mechanical vapor recompression (MVR) and hollow fiber vacuum membrane distillation (HFVMD) was constructed, and several experiments of air tightness, single working condition and multiple working conditions were carried out with ammonium chloride solution as feed, then thermal economic performance were evaluated via a single factor analysis method. The obtained results showed that the system had excellent airtightness to ensure normal evaporation experiment, and high separation efficiency of 99.9% and lower evaporation energy consumption to achieve high efficient separation by combining the advantages of the hydrophobic membrane evaporation and latent heat recovery in view of MVR and HFVMD technologies. Furthermore, increasing feed temperature and feed flow rate increased evaporation rate and decreased evaporation energy consumption, while increasing feed concentration decreased evaporation rate and increased evaporation energy consumption. Finally, the single factor analysis indicated that total investment cost, annual operation cost and annual evaporation capacity were the main factors while environmental cost and equipment service life were the secondary factors which affected the specific evaporation cost. The above research provides theoretical and experimental bases for the development of the proposed system in the future.

Cycle kurtosis entropy guided symplectic geometry mode decomposition for detecting faults in rotating machinery.

Strong noise interference or compound fault coupling phenomenon may lead to the failure of fault diagnosis technology. This paper focuses on weak feature extraction and compound faults detection for rotating machinery fault diagnosis and proposes adaptive symplectic geometric mode decomposition (SGMD) using cycle kurtosis entropy. Firstly, an index named cycle kurtosis entropy (CKE) is presented to measure the strength of periodic impulses in a signal. The CKE uses the entropy value of calculating all delay cycle kurtosis (CK) to overcome the shortcomings of the CK in adaptive ability and obtain more stable values. Thirdly, CKE is applied to construct an adaptive slip window with optimal length. This process is called the adaptive window segmentation method, which is mainly used to dig out weak fault features in signals. Finally, CKE is used as the component selection criterion to select the components decomposed by SGMD. The selected components are reconstructed to obtain a de-noised signal. Hilbert envelope analysis is applied to the denoised signal to demodulate the fault characteristic frequency. Numerical simulations and experimental investigations using bearings and gears are performed to testify the property of the presented method. The results indicate that the adaptive slip window can enhance the decomposing ability of SGMD under strong noise condition. Moreover, for the strong periodic impulse identification ability, the cycle kurtosis entropy is suitable to determine the optimal components of SGMD. It is expected that the presented method will be effectively used for fault feature extractions in rotating machinery under stationary running conditions.

Experimental Study on Productivity Performance of Household Combined Thermal Power and Biogas System in Northwest China.

Ample quantities of solar and local biomass energy are available in the rural regions of northwest China to satisfy the energy needs of farmers. In this work, low-temperature solar thermal collectors, photovoltaic solar power generators, and solar-powered thermostatic biogas digesters were combined to create a heat, electricity, and biogas cogeneration system and were experimentally studied through two buildings in a farming village in northwestern China. The results indicated that the floor heater had the best heating effect. And the fraction of the energy produced by the solar elements of the system was 60.3%. The photovoltaic power-generation system achieved photovoltaic (PV) conversion efficiencies of 8.3% and 8.1% during the first and second season, respectively. The intrinsic power consumption of the system was 143.4 kW·h, and 115.7 kW·h of electrical power was generated by the system in each season. The average volume of biogas produced daily was approximately 1.0 m3. Even though the ambient temperature reached -25°C, the temperature of the biogas digester was maintained at 27°C ± 2 for thermostatic fermentation. After optimization, the energy-saving rate improved from 66.2% to 85.5%. The installation reduced CO2 emissions by approximately 27.03 t, and the static payback period was 3.1 yr. Therefore, the system is highly economical, energy efficient, and beneficial for the environment.