Experimental study on vacuum membrane distillation system of hollow fiber coupled with mechanical vapor recompression

In order to solve the problems of low separation efficiency and high energy consumption in the industrial wastewater treatment, a combined system of mechanical vapor recompression and hollow fiber vacuum membrane distillation was constructed. The operational characteristics of the coupled system were investigated, and experimental studies were conducted on the evaporation of ammonium chloride solution under different feed conditions and long-term operation. The results indicated that as ammonium chloride mass concentration, feed temperature, feed flow rate and vacuum side pressure were 5%, 75 ℃, 10 m3/h and 24 kPa, the freshwater production ratio, freshwater conductivity, separation efficiency and specific heating energy consumption(SHEC) were obtained as 45.9 kg/h, 11.9 μS/cm, 99.9% and 118.5 kW·h/t. In addition, the increase of ammonium chloride mass concentration decreased the freshwater production ratio and increased the SHEC, while the increase of feed temperature and feed flow rate increased the freshwater production ratio and decreased the SHEC. After 240 h of long term operation, membrane fouling did not significantly affect the freshwater quality, but reduced the freshwater production ratio. The water production rate was restored to 96.1% of the original through membrane cleaning. The system can separate the ammonia chloride solution with high efficiency and has a broad application prospect

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