Two kinds of bio-carbons were developed by carbonization/and chemical activation of walnut shell (WS) as lightweight, porous, low-cost and environmental friendly supporting matrix. The produced walnut shell carbon (WSC) and activated WSC (AWSC) were evaluated as novel shape stabilizer and thermal conductivity enhancer for methyl palmitate (MP) preferred as phase change materials (PCM) for thermal controlling applications in buildings. The surface area and pore volume of WS was increased by 1.47 and 1.44 times, respectively after its chemical activation process. WSC and activated AWSC significantly prevented the leakage of liquid MP through phase change due to their suitable adsorption capacities reaching 43 and 55%, respectively. The SEM investigation demonstrated that the MP was well confined into pores of CHW and ACHW carriers. The FTIR and XRD examinations proved the presence of well physicochemical compatibility between the components of the leak-free composites. The DSC measurements indicated that the melting temperatures of WSC/MP and AWSC/MP were 26.27 and 26.65°C, and corresponding fusion enthalpies were 108.3 and 138.1 J/g, respectively. The leak-free composite PCMs were showed remarkable chemical structural stability and thermal reliability after 1000 heating/cooling cycles. Both composites had considerably high thermal degradation stability. The thermal conductivity of leak-free WSC/MP and AWSC/MP was measured as about 1.9 and 1.58 times higher than that of MP. All findings revealed that the leak-free composite PCMs can be used as admixture in the manufacture of lightweight, cost-effective, eco-friendly and energy-saving construction elements utilized for solar thermal controlling of buildings.

通过核桃壳（WS）的碳化/化学活化，开发了两种生物碳，它们是轻质，多孔，低成本和环保的支撑基质。所生产的核桃壳碳（WSC）和活化的WSC（AWSC）被评估为新型棕榈酸酯（MP）的形状稳定剂和导热增强剂，优选用作建筑热控制应用中的相变材料（PCM）。经过化学活化处理后，WS的表面积和孔体积分别增加了1.47和1.44倍。WSC和活化的AWSC由于其合适的吸附能力分别达到43％和55％，因此可显着防止液体MP通过相变泄漏。SEM研究表明，MP被很好地限制在CHW和ACHW载体的孔中。FTIR和XRD检查证明了无泄漏复合材料各组分之间具有良好的物理化学相容性。DSC测量表明，WSC / MP和AWSC / MP的熔融温度为26.27和26.65℃，相应的熔融焓分别为108.3和138.1J / g。经过1000次加热/冷却循环后，无泄漏复合材料PCM具有出色的化学结构稳定性和热可靠性。两种复合材料均具有相当高的热降解稳定性。经测量，无泄漏WSC / MP和AWSC / MP的热导率分别是MP的1.9和1.58倍。所有发现都表明，无泄漏的复合材料PCM可以用作轻质，高性价比，