كليدواژه :
دودكش خورشيدي , ديوار جاذب مياني , ترموسيفون , المان‌بندي
چكيده فارسي :
در اين تحقيق عملكرد يك دودكش خورشيدي با شار حرارتي متفاوت خورشيد روي آن و استفاده از ديواره جاذب در ميان دودكش با استفاده از پديده‌ي ترموسيفون مورد بررسي قرار گرفته است. شدت و تمركز انتقال حرارت و پارامترهاي هندسي مربوط به دودكش خورشيدي از قبيل محل ورودي، ضخامت و طول ديوار جاذب و محل ديوار جاذب در ميزان دبي هواي جابه‌جا شده بررسي و مقادير بهينه براي دبي هواي بيشينه استخراج شده است. معادلات مربوط به جريان درون دودكش خورشيدي با استفاده از تقريب بوزينسك و در نظر گرفتن خواص فيزيكي ثابت و جريان پايدار، طي يك تحليل عددي با استفاده از روش حجم محدود حل شده است و صحت نتايج با نتايج عددي و تجربي ديگران بررسي شده است. همچنين در اين پژوهش المان‌بندي ديوار جاذب به عنوان راهكاري جديد براي افزايش پديده‌ي ترموسيفون و دبي هواي خروجي در دودكش خورشيدي ارائه شده است.
چكيده لاتين :
The design of air conditioning systems is one of the effective factors in optimizing energy consumption in residential and commercial buildings. In this study, the performance of a solar chimney with different solar thermal flux on it and the use of an absorbent wall in the chimney have been investigated. Increasing the air temperature adjacent to the absorbing wall has the effect of thermosyphon in the chimney that ultimately leads to continuous air movement inside the chimney. In most of the proposed designs for these chimneys, the absorbing wall is one of the sidewalls. With sunlight warming up the wall, the air flows into the chimney. By heating the absorbing wall and increasing the temperature gradient, some heat in this wall will be lost through the conduction phenomenon in the wall thickness to the outside or inside the building. In the proposed scheme, the absorbing wall is located in the middle of the chimney and since the optimum width for the chimney is between 0.2m and 0.3m, in the proposed scheme, the distance between each wall and the intermediate absorbing wall is equal to 0.25m. In order to simulate the flow field, the equations of mass, momentum, and energy conservation are solved in the two-dimensional form with constant, incompressible, and turbulent flow assumptions simultaneously. To solve the equations, an academic code based on Fortran's language and SIMPLE algorithm is used. Due to the nature of the turbulent flow of air within the solution field, the k−varepsilon turbulent model is used because of the good performance of this model in simulating boundary layer flows with high reciprocating gradients. The
intensity and concentration of heat transfer and geometric parameters related
to the solar chimney, such as the entrance area, the thickness and length of the absorbing wall, and the location of the absorbing wall in the amount of discharged air flow have been investigated and the optimal values for maximum air discharge have been extracted. Moreover the absorbent wall partitioning is presented as a novel solution to increase the thermosyphon phenomenon in the solar chimney.
