مدلسازی عددی سه‌بعدی تونل‌های ژئوترمال و میزان انرژی دریافتی

امروزه با گسترش تونل‌های قطار شهری، تامین گرمایش و سرمایش ایستگاه‌ها، اهمیت بسیار زیادی دارد. انرژی زمین‌گرمایی کم‌عمق، به عنوان یک انرژی تجدیدپذیر توانسته است به مقدار قابل توجهی در کاهش انرژی موردنیاز برای تامین تهویه و گرمایش سرمایش ایستگاه‌های قطار شهری کمک کند. میزان انرژی دریافتی از سیستم نوین ذکر شده در ارزیابی اقتصادی طرح اهمیت بسزایی دارد. از این رو، در پژوهش حاضر سعی شده است با ارائه‌ی یک مدل‌سازی المان محدود، میزان انرژی دریافتی در تونل‌های مجهز به سیستم مبادله‌گر حرارتی در 16 روز بررسی شود. پس از صحت‌سنجی مدل‌سازی صورت گرفته، اثر پارامترهای مختلف مدل‌سازیدر دو حالت عایق و غیرعایق بررسی شده است. در شرایط غیرعایق، میزان توان انرژی خروجی وابسته به شرایط حاکم بر فضای داخلی تونل است.براساس نتایج به دست آمده در هر دو شرایط عایق و غیرعایق، تحت تاثیر عملیات مستمر استخراج انرژی، توان انرژی خروجی با گذشت زمان کاهش یافته است.

3d numerical modeling of geothermal tunnels and receivable energy

nowadays, with development of subway tunnels, heating and cooling stations are playing an important role. shallow geothermal energy as a renewable timeindependent energy source helped significantly to reduce energy consumption for supplying ventilation, heating, and cooling of subway stations. the amount of accessible energy from such modern systems is of great importance in their economic assessment. hence, this research aims to perform and present finite element modeling to evaluate the amount of exploited energy through ground heat exchangers (ghe) in tunnels. after validation of implemented modeling, the effect of various involved parameters in modeling was studied for a shortterm operation of heat exchange. additionally, the effect of lining isolation with respect to the inner environment of the tunnel was investigated. the results show that by increasing water velocity in the pipe, the total extracted power increased in both isolated and nonisolated conditions. the results can be classified into three main categories.1. by increasing (a) the spacing between the pipe and inner environment of the tunnel in isolated case, (b) the inner temperature of the tunnel in nonisolated case, and (c) thermal conductivity of soil in both isolate and noneisolate cases, the total extracted power could be improved. the pipe diameter has a fascinating effect on the total extracted power. firstly, it reduces the amount of extracted power. however, in the case of larger diameters, due to the capability of discharging more water, the amount of extracted power is increased. 2. by increasing (a) the spacing between the pipe and inner environment of the tunnel in nonisolated conditions and (b) pipe thickness in both nonisolated and isolated conditions, the total extracted power is reduced.3. by increasing the specific heat capacity, density, and porosity of the soil, the total extracted power slightly changes. indeed, these parameters have a negligible effect on extracted power.