超长重力热管传热性能实验研究

用于干热岩热能开采的增强型地热系统存在投资高、风险大、工质漏损、设备腐蚀、地面沉降等问题，利用超长重力热管进行地热开采可以有效规避这些问题。搭建了超长重力热管实验平台，实验研究了超长重力热管的适宜充液量、运行的稳定性和不同冷却水流量下的传热性能并分析了其可能的原因；研究表明在恒定加热功率下，热管的合适充液量为蒸发容积的40%左右，在运行期间，与传统短热管相比，超长热管展现出了强烈的振荡性，振荡频率与加热功率和充液量息息相关；在恒定加热功率下，随着冷却水流量的增加，热管采出功率先增加后逐渐趋于平缓。此外，特别探讨了热管在极端充液量下的传热性能，研究表明在极端充液量下，热管底部形成一定高度的气柱，由于气柱的持续存在导致热量无法传递到热管顶端。实验结果初步证实了超长重力热管在开采干热岩热能上的可行性，为下一步的实际应用提供了基础支持。

Experimental study on heat transfer performance of super long gravity heat pipe

There are many problems in the enhanced geothermal system used for dry hot rock thermal energy exploitation, such as high investment, high risk, working medium leakage, equipment corrosion, land subsidence,etc. Using super long gravity heat pipe to mine hot dry rock geothermal energy can effectively avoid these problems. In this paper, an experimental platform for super long gravity heat pipe is built. The suitable liquid filling capacity, stability of operation and heat transfer performance under different cooling water flow rates are studied experimentally. The possible causes are analyzed. The research shows that under the constant power, the suitable liquid filling amount of the heat pipe is about 40% of the total liquid filling amount of the evaporation section. During operation, compared with the conventional short heat pipe, the super long heat pipe exhibits strong oscillation, oscillation frequency and heating power and charging. The amount of liquid is closely related. At a constant heating power, as the flow rate of the cooling water increases, the power of the heat pipe increases first and then gradually becomes gentle. In addition, the heat transfer performance of the heat pipe under the extreme liquid filling amount is especially discussed. The research shows that under the extreme liquid filling amount, the gas column forms a certain height at the bottom of the heat pipe, and the heat cannot be transferred to the top of the heat pipe due to the continuous existence of the gas column. The experimental results preliminarily verify the feasibility about using the super long gravity heat pipe to mine hot dry rock geothermal energy and offer fundamental supports for the future practical applications.