基于石墨混凝土的能源桩传热特性强化研究

Study on heat transfer enhancement of energy pile based on graphite concrete

能源桩能够充分利用混凝土良好导热性能,与周围土体进行换热。为了增强能源桩传热特性,向能源桩内添加高导热系数的石墨粉而制备出石墨混凝土桩体材料,并研究其导热及力学性能。结果表明,随着石墨体积比的增大,石墨混凝土试块导热系数呈加速上升趋势。当石墨体积比增至8%(占混凝土体积分数),其导热系数上升至2.73W/(m·K);抗压强度随着石墨体积比的增大而降低。与纯混凝土相比,添加5%石墨的混凝土,其导热系数增长近1倍,抗压强度下降23%,此添加率下的石墨添加方案为传热强化与强度下降的合理方案。COMSOL软件的有限元数值模拟结果也证明,添加5%石墨混凝土的能源桩的换热能力较普通能源桩更强。

Energy pile fully utilizes the good thermal conductivity of concrete and exchanges heat with the surrounding soil.In order to enhance the heat transfer characteristics of energy piles,graphite powder with high thermal conductivity was added into concrete,and its thermal conductivity and mechanical properties were studied.The results show that:as the volume ratio of graphite increases,the thermal conductivity of the graphite concrete has an accelerated upward trend.When the volume ratio of graphite increases to 8%(accounting for the volume fraction of concrete),its thermal conductivity rises to 2.73W/(m·K);The compressive strength decreases as the volume ratio of graphite increases.Compared to conventional concrete,5%graphite additive rate is the recommended solution considering the doubled thermal conductivity and 23%strength reduction.The finite element numerical simulation results of COMSOL software also proved that the heat transfer capacity of energy piles using 5%graphite concrete is stronger than that of ordinary energy piles.