Metal-organic frameworks (MOFs) have recently garnered attention due to their intriguing physiochemical properties; however, their instability and unsatisfactory processability have limited them from achieving a wide range of applications. Therefore, structural new MOFs and MOF-based hydrogels have been developed to address associated drawbacks (such as inherent brittleness and instability in the crystalline state). The development of MOF-based hydrogels has been the focus of some recent attempts. Compared to the original MOFs, they have several better properties (such as improved mechanical strengths). This review will provide the latest overviews of current research developments on MOF-based hydrogels. We primarily focus on the classification of these hydrogels and their associated synergistic effects. We also emphasize microscale composite design, macroscale performance, and extended applications in catalysis, water treatment and biomedicine. Further, we anticipate that this review will be valuable for individuals seeking insights into the applications of MOFs-based hydrogels.

The heat-pipe solar water heating (HP-SWH) system and the heat-pipe photovoltaic/thermal (HP-PV/T) system are two practical solar systems, both of which use heat pipes to transfer heat. By selecting appropriate working fluid of the heat-pipes, these systems can be used in the cold region without being frozen. However, performances of these two solar systems are different because the HP-PV/T system can simultaneously provide electricity and heat, whereas the HP-SWH system provides heat only. In order to understand these two systems, this work presents a mathematical model for each system to study their one-day and annual performances. One-day simulation results showed that the HP-SWH system obtained more thermal energy and total energy than the HP-PV/T system while the HP-PV/T system achieved higher exergy efficiency than the HP-SWH system. Annual simulation results indicated that the HP-SWH system can heat the water to the available temperature (45°C) solely by solar energy for more than 121 days per year in typical climate regions of China, Hong Kong, Lhasa, and Beijing, while the HP-PV/T system can only work for not more than 102 days. The HP-PV/T system, however, can provide an additional electricity output of 73.019 kWh/m², 129.472 kWh/m², and 90.309 kWh/m² per unit collector area in the three regions, respectively.

As global photovoltaic (PV) installation capacity grows rapidly, the environmental pollution and resource waste from the large-scale end-of-life (EOL) wave have drawn increasing attention. Traditional disposal methods such as landfilling and incineration are no longer viable, making green recycling a logical path for the PV industry. This paper reviews recent progress in the disassembly and recycling of EOL crystalline silicon (c-Si) PV modules. It first describes the structural material composition of c-Si PV modules and summarizes global recycling policies and regulatory frameworks. It then analyzes the mechanisms and process parameters of major delamination technologies, including mechanical crushing, pyrolysis, thermal cutting, high-voltage pulse fragmentation, solvent-based approaches, and laser peeling. Methods for purifying silicon and recovering precious metals such as silver and copper are also covered. Finally, key challenges in the recycling field and future development trends are discussed, with the aim of supporting the advancement of c-Si PV recycling technologies and the sustainable development of related industrial chains.

To mitigate stress imposed on power grids by air source heat pumps (ASHP) during peak electricity demand periods, a time-phase operated heat pump heating system integrated with phase change heat storage was proposed and developed. A control strategy coupling the phase change temperature of the heat storage module (Tp) with indoor temperature (Ti) was implemented using a PLC-based control module. System performance, under heat storage, heat release, and heating-only modes was experimentally evaluated across multiple operating condition. Continuous dynamic experiments over several days were conducted to determine temperature thresholds of the heat storage module and analyze system dynamic behavior, energy efficiency, and temperature stability. Results demonstrate that the proposed system provides stable and continuous heating, maintaining indoor temperatures within 18.0-20.0°C. The heat storage module showed stable heat storage and release performance within 40.0-44.0°C. The actual operating temperature threshold was lower than the material phase change temperature due to thermal resistance. During peak electricity demand periods, household heating can be achieved exclusively by the heat storage module, resulting in near-zero electricity consumption. During mid-peak periods, the heat pump operates in heating-only mode for approximately 35% of the total operating time. The proposed system demonstrates strong robustness during 72 h of continuous operation, improving heating stability by 40% during peak periods and reducing the daily operating time of the heat pump by 25%. Economic analysis indicates that the proposed system achieves a cost reduction of 19% compared with conventional ASHP systems, highlighting its potential for practical application.

Advanced Sludge dewatering system is investigated by the approaches of physical and chemical pretreatment process to improve sludge dewatering performance, based on the degree of difficulty or ease together with the relationship analysis of the existing form of the sludge water. Systems of sludge pre-treatment, sludge filter press and auto-control are elucidated significantly, with the aim that accomplishing the sludge deep dewatering, and making the moisture content of sludge below 55%. This approach can suit to the manipulating locally of the sludge in the sewage treatment plant and save the investment of sludge storage storehouse as well as the cost of transportation.