IJE TRANSACTIONS B: Applications Vol. 31, No. 5 (May 2018) 805-811    Article in Press

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G. V. Pradeep and K. Rama Narasimha
( Received: July 31, 2017 – Accepted in Revised Form: April 26, 2018 )

Abstract    This paper presents the experimental investigations conducted on a vertical closed loop pulsating heat pipe (VCLPHP) to evaluate the thermal performance. The values of thermal resistance and heat transfer coefficient obtained in the experimentation is used as evaluation parameters. The VCLPHP used has capillary tubes having an inner diameter of 2mm and outside diameter 3mm and bent into 5 turns. The lengths of the evaporator, adiabatic and condenser sections are 50, 90 and 70mm, respectively. The binary mixture of fluids used are acetone – ethanol and ethanol - methanol mixtures. The thermal performance of these binary mixtures were then compared with conventional working fluids such as acetone, ethanol and methanol. The fill ratios was changed from 50 to 80% in steps of 10% and the heat inputs were varied between 60 to 90W in steps of 10W. However, the mixing proportions for all mixtures was maintained as 1:1. All the experiments were conducted in the vertical position (90°). The experimental results showed that, the overall performance of acetone was the best with the lowest thermal resistance and highest heat transfer coefficient as compared to all pure fluids and among fluid mixtures the acetone-ethanol mixture showed the best thermal performance.


Keywords    Pulsating Heat Pipe; Binary Mixture of Fluids; Thermal Performance; Thermal Resistance


چکیده    در اين مقاله، مطالعات آزمايشگاهي انجام شده بر روي يك لوله گرماي پالستيك عمودي بسته با حلقه عمودي (VCLPHP) براي ارزيابي عملكرد حرارتي ارائه شده است. مقادیر مقاومت حرارتی و ضریب انتقال گرما به دست آمده در آزمایش به عنوان پارامترهای ارزیابی استفاده می شود. VCLPHP دارای لوله های مویرگی با قطر داخلی 2 میلی­متر و قطر خارجی 3 میلی متر و به 5 نوبت خم شده است. طول بخش های تبخرکننده، آدیاباتیک و کندانسور به ترتیب 50، 90 و 70 میلی متر است. مخلوط دوتایی از مایعات مورد استفاده استون - اتانول و اتانول - متانول مخلوط می باشند. عملکرد حرارتی این مخلوط های دوتایی سپس با مایعات کار مرسوم مانند استون، اتانول و متانول مقایسه شد. نسبت پر شدن از 50٪ تا 80٪ در مراحل 10٪ تغییر کرد و ورودی های گرما بین 60 تا 90 وات در 10 وات متغیر بود. با این حال، نسبت مخلوط برای تمام مخلوط به عنوان 1: 1 حفظ شد. تمام آزمایش ها در موقعیت عمودی (90 درجه) انجام گرفت. نتایج آزمایشی نشان داد که عملکرد کلی استون بهترین است با کمترین مقاومت حرارتی و بیشترین ضریب انتقال حرارت در مقایسه با تمام مایعات خالص و در میان مخلوط مایعات، مخلوط استن و اتانول بهترین عملکرد حرارتی را نشان می دهد.


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