مطالعه‌ي عددي و تجربي يك دستگاه ذخيره سازي انرژي گرمايي حاوي ماده تغيير فاز

Modeling and Simulation of a Latent Heat Thermal Energy Storage System (LHTES) containing Phase Change Materials

نياز روز افزون بشر به انرژي، محدوديت منابع انرژي، آلودگي هوا بر اثر انتشار گازهاي آلاينده ناشي از احتراق سوخت‌هاي فسيلي، و گرم شدن زمين همگي از مواردي هستند كه صرفه جويي و مصرف بهينه انرژي را اجتناب ناپذير مي‌كنند. يكي از راه هاي پيش رو ذخيره‌سازي انرژي در دسترس و استفاده از آن در مواقع مورد نياز است. ذخيره‌سازي سرماي شب و استفاده از آن براي تهويه‌ي هواي روز در مناطق كويري كه اختلاف دماي شب و روز قابل ملاحظه است، در كنار سيستم هاي تهويه‌ي متداول و پرمصرف يا به‌جاي آن، يكي از فرصت‌هاي صرفه‌جويي در مصرف انرژي است. در اين پژوهش يك مدل يك‌بعدي براي حل يك سامانه‌ي ريژنراتور با بستر ثابت حاوي مواد تغيير فاز پلي اتيلن گليكول 600 در پوشش هاي مكعب مستطيلي ارايه، و نتايج حاصل از حل آن با نتايج آزمايشگاهي مقايسه شده است.

The growing need for energy, considering limited energy resources, pollution and global warming, have forced people to be more sensitive about the rate of energy consumption. Despite this fact, because of rising living standards, there is an increasing demand for cooling systems in buildings around the world. This increasing demand has led to a peak in electrical power consumption during hot summer days. Finding a solution for this peak is a new challenge for scientists. A leading option is to save available energy for use when it is needed. Saving the coldness of the night air for air conditioning during the hot summer days of tropical regions, instead of using common cooling devices, could be a proper opportunity to save energy. This idea is not only a good option for solving the electrical power imbalance between supply and demand, but also shifts the cooling energy use to off-peak periods and avoids peak demand charges. Phase Change Materials (PCM), because of their unique specifications, such as their capability of melting and freezing at a selected temperature, and their promising ability to reduce the dimensions of storage systems compared with usual storage systems (because they use the latent heat of the storage medium for thermal energy storage), can be used for this purpose. Initially, deriving a mathematical model for describing a heat exchanger pached with phase change Materials is essential. For this propose, a Latent Heat Thermal Energy Storage system (LHTES), containing flat slabs of Phase Change Material (PEG 600), has been investigated numerically and experimentally. For the numerical investigation, a one-dimensional model considering axial conduction and using effective heat capacity has been proposed to describe the built LHTES. The results of the model and experiments were compared, and good agreements were achieved.