A tube of soda glass has an internal diameter of 18 mm and a wall thickness of 2 mm. The is to be used as a heat exchang

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A Tube Of Soda Glass Has An Internal Diameter Of 18 Mm And A Wall Thickness Of 2 Mm The Is To Be Used As A Heat Exchang 1 (394.82 KiB) Viewed 17 times

A tube of soda glass has an internal diameter of 18 mm and a wall thickness of 2 mm. The is to be used as a heat exchanger, with the outer surface immersed in agitated boiling water, and ice-cold fluid flowing through the bore. 1) Estimate the maximum value of temperature difference between the outer and inner surfaces of the tube that the glass can stand without fracturing. Use data from the Table, and assume a value for Poisson's ratio of 0.3. Assume that the tensile strength of the glass in this application is approximated by the modulus of rupture 2) Estimate the maximum heat flow rate (expressed per 100 mm length of tube) which the tube can stand. Explain how differences between the properties of soda glass and Pyrex borosilicate glass (see Table) would help to increase the maximum temperature difference if Pyrex were used instead. Why is Pyrex glass always used for chemistry experiments? PROPERTIES OF CERAMICS Melting (softening) Thermal expansion coefficient Cost (UK£ (US$) tonne ¹) Young's modulus (GPa) Fracture toughness (MPa m¹2) Specific heat Thermal conductivity temperature (K) Modulus of rupture (MPa) Ceramic (J kg ¹K¹) (Wm¹K¹) (X106 K-¹) 74 0.7 (1000) 990 8.5 50 700 (1000) 1000 (1400) 65 0.8 (1100) 800 4.0 55 70 1.0 (1400) 800 1 3 45 260-1000 (360-1400) 1050 510 1.2 4 × 108 (6 × 108) Expensive at 380 3-5 2323 (1470) 795 8.5 300-400 410 3110 1422 4.3 200-500 present. Potentially 310 4 2173 627 3.2 300-850 350-1000 200 2843 8 200-500 4-12 5 670 710 (490-1400) 300 3.2 500-830 52 (73) 26 (36) 20-30 30-50 0.2 0.2 10-14 10-14 7 Cost of mining 63 0.9 20 and transport 60-80 8 23 0.12 Glasses Soda glass Borosilicate glass Pottery, etc. Porcelain High-performance engineering ceramics Diamond Dense alumina Silicon carbide Silicon nitride Zirconia Sialons Cement, etc. Cement Concrete Rocks and ice Limestone Granite Ice 9.1 11 273 (250) 70 25.6 84 17 1.5 20-25 1.8 2 1.7