The rapid development of industry has emphasized the importance of phase change materials (PCMs) with a high latent-heat storage capacity and good thermal stability in promoting sustainable energy solutions. However, the inherent low thermal conductivity and poor thermal-cycling stability of PCMs limit their application. In this study, we constructed three-dimensional (3D) hybrid graphene aerogels (GBA) based on synergistic assembly and cross-linking between GO and modified hexagonal boron nitride (h-BN). Highly thermally conductive GBA was utilized as the supporting optimal matrix for encapsulating OD, and further implied that composite matrix n-octadecane (OD)/GBA composite PCMs were further prepared by encapsulating OD within the GBA structure. Due to the highly thermally conductive network of GBA, the latent heat of the composite PCMs improved to 208.3 J/g, with negligible changes after 100 thermal cycles. In addition, the thermal conductivity of the composite PCMs was significantly enhanced to 1.444 W/(m·k), increasing by 738% compared to OD. These results sufficiently confirmed that the novel GBA with a well-defined porous structure served as PCMs with excellent comprehensive performance offer great potential for thermal energy storage applications.
According to Surface Water Environment Quality Level, a surface water environment quality survey data management and analysis system which coincides with the situation in Heilongjiang had been built. It has improved our work efficiency and has practice meaning.
Abstract The development of China's coalbed methane (CBM) industry is restricted by the complex geological conditions, unmatched technology and lack of development experience. To solve this problem, a case library covering typical CBM fields at home and abroad is established. Through data analysis and mining, the differences between domestic and foreign CBM fields are compared and the influence factors of CBM single well production were analyzed. This study includes the data preparation of CBM fields, the establishment of the case library system, the establishment of data analysis model and the result analysis. The data of case library covers the geological conditions, development history, main technology and economy of CBM field. The case library is based on the MVC development idea and adopts the object-oriented method. The analysis of data includes correlation analysis of single well production and quantitative gap analysis. The case library contains a number of typical case data, such as San Juan, Black warrior, Bowen, Surat, Qinshui, Hancheng, etc. The relevant parameters of different CBM fields can be quickly compared by using the case library. By mining the data such as coal rank, permeability, thickness, depth, gas content and proved reserves, the influence factors of single well production of CBM well are analyzed quantitatively. It is found that the thickness and permeability of coal seam have the greatest influence on single well production. Quantitative gap analysis shows that there is a large gap between the coal seam thickness, permeability, the gas drainage technology and well production improvement technology of domestic CBM fields compared with the foreign fields with the best development effect. Through the application of CBM case library, data is analyzed and utilized effectively and data values are fully exploited. This study provides an effective way to analyze the gap of CBM in China and draw lessons from abroad.
Novel microencapsulated phase change materials (micro-PCMs) were synthesized via in-situ polymerization with modified carbon nanotubes(CNTs) reinforced melamine-formaldehyde resin as shell material and CNTs reinforced n-octadecane as PCMs core. DSC results confirm that the micro-PCMs possess good phase change behavior and excellent thermal cycling stability. Melting enthalpy of the micro-PCMs can achieve 133.1 J/g and has slight changes after 20 times of thermal cyclings. And the incorporation of CNTs supplies the micro-PCMs with fast thermal response rate which increases the crystallization temperature of the micro-PCMs. Moreover, the thermal conductivity of the micro-PCMs has been significantly enhanced by introducing CNTs into their shell and core materials. And the thermal conductivity of micro-PCMs with 1.67 wt.% CNTs can increase by 25%. These results exhibit that the obtained micro-PCMs have a good prospect in thermal energy storage applications.
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