Bünyesinde su bulunan sıkıştırılmış kar kürelerde ısı transferinin incelenmesi

Gemıcı, Zafer; Eğrƒcan, A. Nilüfer
April 2010
ITU Journal Series D: Engineering;Apr2010, Vol. 9 Issue 2, p71
Academic Journal
It is possible to use the natural snow accumulated on mountains for the aim of refrigeration when needed, especially in summer times. Making ice spheres from snow is suggested for transferring this accumulated snow from mountains to the places where refrigeration is needed. In this study, ice-sphere making process and heat and mass transfer mechanisms during this icing process are investigated experimentally. Today, transferring of ice for long distances is realized in the mixture form of snow and water. The most important disadvantage of transferring of snow mixture in pipe lines is the blockage of the flow because of accumulation of the snow in the elbows which is the place of flow direction changes. Another important disadvantage is large pressure losses. To overcome all these problems ice-spheres are being suggested. In this study, firstly making snow balls by compression, and then, saturating them with water and lastly, getting ice ball by cooling is aimed. To prevent the blockage of the balls in the pipeline's elbows, the diameter of the balls should be chosen bigger than the radius of the pipe. Otherwise, we will meet a flow characteristic called slush flow in the literature. In this study, the aimed flow is known as plug flow. In the literature, the plug flow of the plastic balls examined by Ulusarslan (2003) experimentally. In the mentioned study, the plug flow of the plastic balls was investigated and pressure losses of the flow determined experimentally. In addition, plug and slug flow are compared with each other. According to the study in the plug flow; - Pressure losses are less. - There is no blockage risk. - It is possible to carry more mass. - Less power is required to carry. During the transfer of the balls in the pipelines, icing of the snow balls has to be done to prevent breaking into pieces. The icing process is done by compression of the snow into the form of sphere and saturating it with water. Water can be used as a binder. The most important think here is how much water should be used in the penetration process. The excess water causes the balls breaking into pieces. On the other hand, the less water amount causes insufficient binding of the snow granules. By compression of the balls, the air gaps inside the snow balls are decreased. Thus the density of the snow increases depending on the compaction level. At the end, the bonds between snow granules will be stronger. Compaction level, compaction velocity and temperature are very important parameters affecting the process. It is very important to determine correctly which values of the parameters should be used to have enough strength of the snow ball during the transfer process. …


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