1. Introduction to Achievements
The application of graphene aerogels prepared by reduction self-assembly method and ice template method is limited due to their difficult shape control and poor compression resistance. In this paper, researchers from Southwest University of Science and Technology, such as Fang Fang He, published a paper entitled "Shape stabilized phase change materials based on polyvinyl alcohol/graphene hybrid aerogels for efficient solar thermal energy conversion" in the journal Mat Sci Semiconductor Proc. They studied the preparation of a Series PVA/graphene aerogels (PGA).
The cross-linking effect and PVA enhancement effect realized the shape control of aerogel and enhanced its compression resistance. When the content of graphene oxide is 50 mg, the PGA5 mixed air gel obtained has better compressive properties, and the compressive strength when 50% compressed is 6.26 KPa. Then, PEG was added to PGA by vacuum impregnation method to prepare PGA@PEG Shape stable phase change materials (SSPCMs). Prepared with PGA5 PGA5@PEG The thermal conductivity is as high as 0.481 W m-1 K-1, with excellent energy storage performance (phase transition enthalpy of 178.6 J/g) and good thermal cycling stability. In addition, PGA5@PEG The photothermal conversion efficiency is as high as 86.9%.
Therefore, we have designed a solar hot water system to broaden the application of SSPCM in the field of solar thermal energy conversion. During the 2-hour heating process, PGA5@PEG- The water system can quickly reach a maximum temperature of 57.3 ℃, which is higher than the pure water system (40.4 ℃). PGA@PEG The application prospects of SSPCMs as latent heat storage/release units in the field of solar energy storage and conversion are very broad.
2. Text and Image Introduction
Figure 1. (a) PGAn and PGAn@PEG The preparation process of SSPCMs. (b) Schematic diagram of PGA synthesis route.
Figure 2. (a-d) Digital photos of PGA2, PGA3, PGA4, and PGA5, from left to right. SEM images of PGA2, PGA3, PGA4, and PGA5, from left to right.
Figure 3. (A-C) XPS measurement spectra of GO, PGA, and c-PGA. The C 1s spectra of GO (d), PGA5 (e), and c-PGA5 (f). The N 1s spectra of PGA (g) and c-PGA (h). (i) Fourier transform infrared spectra of GO, PVA, PGA, and PVA-APDEMS.
Figure 4. (a) PEG and PGA5@PEG The digital photos. (b) PEG and PGA5@PEG Digital image of 500g weight under isothermal heating at 65 ° C.
Figure 5. (a) PEG and PGA@PEG The thermal conductivity coefficient. (b) During heating and (c) cooling, PEG and PGA5@PEG Infrared thermal imaging.
Figure 6. Experimental setup for solar hot water (a) Heating process and (b) Cooling process; (c) Simulate a pure water system under sunlight and PGA5@PEG Time temperature curve of water system; (d) Schematic diagram of residential solar thermal water storage system.
3. Summary
In this study, a SSPCM material based on PGA hybrid aerogel and PEG was successfully prepared for efficient conversion and utilization of solar energy. A series of PGA hybrid aerogels with different GO contents were prepared by APDEMS chemical assisted crosslinking and freeze drying techniques. Then, PEG was injected into PGA hybrid gas gel through vacuum impregnation to prepare PGA@PEG SSPCM。 The prepared PGA has good compression resilience. When the GO concentration is 5 mg/mL, the compressive strength of PGA5 under 50% compression is as high as 6.26 KPa. PGA5@PEG It has good heat storage capacity, with a phase transition enthalpy of 178.6 J/g and a thermal conductivity of 0.481 W m − 1K − 1, which is 131.25% higher than pure PEG. PGA5@PEG The photothermal conversion efficiency is 86.9%. In a solar thermal water storage system, PGA5@PEG The water system heats up rapidly, reaching a maximum temperature of 57.3 ° C, higher than the pure water system (40.4 ° C). These results indicate that, PGA@PEG It has potential application prospects in solar energy collection and conversion systems.
