ENHANCING STORAGE PERFORMANCE IN A TUBE-IN SHELL STORAGE UNIT BY ATTACHING A CONDUCTING FIN TO THE BOTTOM OF THE TUBE

Öz

In this experimental study, melting behavior of paraffin in a storage unit of the horizontal shell-and-tube type is investigated. In order to enhance melting rate, a conducting fin is attached to the bottom of the inner tube. At first, the tube without a fin is tested. Then, the tubes with fin of four different heights (h=10, 20, 30 and 40 mm) are examined. Experiments are conducted at constant values of the inlet temperature and the inlet mass flow rate of the heat transfer fluid (HTF). As phase change material (PCM), paraffin (solidification range of 56−58 C) is used. For each case tested, transient variations of the temperature at some specific radial points inside the phase change material (PCM) are obtained. For the case without a fin, natural convection recirculation is shown to be weak in the lower half region of the annulus when compared to that in the upper half region. Results show that attaching a conducting fin to the bottom of the inner tube intensifies the recirculation of liquid PCM in the lower half and, in follows, enhances the melting rate about 72.8% for the fin height of 40 mm when compared to without fin (h=0 mm)

Anahtar Kelimeler

• thermal energy storage
• tube-in-shell
• finned tube
• PCM
• melting enhancement

HALKASAL GEOMETRİYE SAHİP SİLİNDİRİK BİR DEPONUN ISI DEPOLAMA PERFORMANSININ İYİLEŞTİRİLMESİ: KANATÇIK İLAVESİ

Öz

Bu çalışmada, yatay olarak konumlandırılan silindirik halka aralık bir geometri içerisindeki faz değiştiren maddenin (FDM) erime (şarj) davranışı deneysel olarak incelenmiştir. Erime sürecinin iyileştirilmesi amacıyla ısı transfer borusuna kanatçık ilavesi yapılmıştır. Kanatçıksız durum (h=0 mm) ve dört farklı kanatçık yüksekliği (h=10, 20, 30 and 40 mm) için deneyler gerçekleştirilmiştir. Deneyler, sabit bir hacimsel debide ve tek bir akışkan giriş sıcaklığında yapılmıştır. FDM olarak katılaşma sıcaklığı 56−58 C olan parafin kullanılmıştır. Her bir durum (h) için FDM içerisinde tanımlanan radyal yerel noktalardan zaman bağımlı sıcaklık ölçümleri alınmıştır. Kanatçıksız duruma ait veriler incelendiğinde halka aralığın alt yarı bölgesindeki doğal taşınım mekanizmasının üst yarı bölgeye kıyasla daha zayıf olduğu görülmüştür. Sonuç olarak, ısı transfer borusunun (iç boru) alt kısmına yapılan kanatçık ilavesinin halka aralığın alt bölgesindeki sıvı FDM sirkülasyonunu kuvvetlendirdiği görülmüştür. Kanatçık yükseklikliğinin maksimum olduğu durum (h=40 mm) için erime hızında kanatçıksız duruma (h=0 mm) kıyasla %72.8 oranında iyileşme sağlandığı ortaya konmuştur. termal enerji depolama, ,, ,.

Anahtar Kelimeler

• termal enerji depolama
• halka aralık geometri
• kanatçıklı boru
• FDM
• erimenin iyileştirilmesi

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