Cost-Effective Biochar Produced from Agricultural Residues and Its Application for Preparation of High Performance Form-Stable Phase Change Material via Simple Method
Abstract:A new form-stable composite phase change material (PEG/ASB) composed of almond shell biochar (ASB) and polyethylene glycol (PEG) was produced via a simple and easy vacuum impregnation method. The supporting material ASB, which was cost effective, environmentally friendly, renewable and rich in appropriate pore structures, was produced from agricultural residues of almond shells by a simple pyrolysis method, and it was firstly used as the matrix of PEG. Different analysis techniques were applied to investigate … Show more
“…The composite of PEG/MPC-Cu began to melt at 54.8 °C and to freeze at 38.4 °C, and the peak temperatures in the melting and freezing process were 60.1 °C and 33.5 °C, respectively. Compared to pristine PEG, the peak temperature values of the prepared ss-PCM were lower, which could be explained by the fact that adding MPC-Cu could increase the thermal conductivity of PEG 54 . Figure 10 DSC curves for PEG, MPC-Cu and PEG/MPC-Cu.…”
Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.
“…The composite of PEG/MPC-Cu began to melt at 54.8 °C and to freeze at 38.4 °C, and the peak temperatures in the melting and freezing process were 60.1 °C and 33.5 °C, respectively. Compared to pristine PEG, the peak temperature values of the prepared ss-PCM were lower, which could be explained by the fact that adding MPC-Cu could increase the thermal conductivity of PEG 54 . Figure 10 DSC curves for PEG, MPC-Cu and PEG/MPC-Cu.…”
Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.
“…This result indicated that, the formation of copper microspheres on the surface of WBB did not change the superficial chemical functional groups of WBB. In the spectra of WBB and CMS-WBB, the characteristic absorption peak at 1631 cm −1 originated from the tensile vibration of C=C group, while the peak at 1383 cm -1 was caused by C–C 16 , 26 , 27 . In addition, there were wide peaks at 1010–1120 cm −1 , which were typical graphite properties 18 , 28 .…”
Section: Resultsmentioning
confidence: 99%
“…Among these carriers, biochar attracted much attention owing to its large specific surface and abundant functional groups, which was prepared by pyrolysing biomass, such as forestry and agricultural residues 15 . For example, Chen et al used almond shell biochar (ASB) as supporting material to load polyethylene glycol (PEG) for the synthesis of PEG/ASB ss-PCMs, and the experimental results showed that PEG/ASB had excellent thermal stability and phase transition properties 16 . Although the leakage problem of PCMs could be solved by using biochar as carrier, the thermal conductivity of ss-PCMs still needed to be further improved.…”
Metal microspheres doping porous carbon (MMPC), which was prepared using in-situ pyrolysis reduction strategy, could enhance the thermal conductivity of shape-stabilized phase change material (ss-PCM) prepared by MMPC as the matrix. However, in previous studies that were reported, the preparation of MMPC needed to synthesize porous carbon by pyrolysis firstly, and then porous carbon adsorbed metal ions was pyrolyzed again to obtain MMPC, which was tedious and energy-prodigal. In this study, a one-step pyrolysis strategy was developed for the synthesis of MMPC through the pyrolyzation of wheat bran adsorbed copper ions, and the copper microspheres doping wheat bran biochar (CMS-WBB) was prepared. The CMS-WBB was taken as the supporter of stearic acid (SA) to synthesize the ss-PCM of SA/CMS-WBB. The study results about the thermal properties of SA/CMS-WBB demonstrated that the introduction of copper microspheres could not only improve the thermal conductivity of SA/CMS-WBB, but also could increase the SA loading amount of wheat bran biochar. More importantly, the CMS-WBB could be obtained by only one-step pyrolysis, which greatly simplified the preparation process and saved energy consumption. Furthermore, the raw material of wheat bran is a kind of agricultural waste, which is abundant, cheap and easy to obtain. Hence, the SA/CMS-WBB synthesized in this study had huge potentialities in thermal management applications, and a simplified method for improving the thermal properties of ss-PCMs was provided.
“…The thermal conductivities of PA, PB and PA/PB-4 in this study were measured to be 0.2731, 0.3417 and 0.3926 W/(m∙K), respectively. The conductivity of PB was not very high, and however, it could improve the PA’s conductivity effectively for the reason that when PA was filled into the pores of PB, it could replace the air in the pores, and then the conductivity of PA/PB would be improved and higher than that of both PA and PB 42 . Additionally, the thermal conductivities of different form-stable phase change materials are listed in the Table 4.…”
A promising new form-stable phase change material (PA/PB) was fabricated using pinecone biochar (PB) as the supporting material of palmitic acid (PA). The biochar of PB with large surface area was produced by forest residue of pinecone, and it was cheap, environment friendly and easy to prepare. The PB was firstly utilized as the supporter of PA and the characterizations of PA/PB were analyzed by the BET, SEM, XRD, DSC, TGA, FT-IR and thermal conductivity tester. The results demonstrated that the PA was physically absorbed by the PB and the crystal structure of the PA was not destroyed. The results of DSC showed that the fusing and crystallization points of the form-stable phase change material with the maximum content of PA (PA/PB-4) were 59.25 °C and 59.13 °C, and its fusing and freezing latent heat were 84.74 kJ/kg and 83.81 kJ/kg, respectively. The results of TGA suggested that the thermal stability of the PA/PB-4 composite was excellent, which could be used for the applications of thermal energy storage. Furthermore, the thermal conductivity of PA/PB-4 was 0.3926 W/(m∙K), which was increased by 43.76% compared with that of the pure PA. Thus, the study results indicated that the PA/PB-4 had great potential for thermal energy storage applications.
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