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If a certain amount of steam is produced at a pressure of 8 bar and dryness fraction 0.8. Calculate : (i) External work done during evaporation. (ii) Internal latent heat of steam. |
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Answer» Pressure of steam, p = 8 bar Dryness fraction, x = 0.8 At 8 bar. From steam tables, vg = 0.240 m3/kg, hfg = 2046.5 kJ/kg (i) External work done during evaporation = pxvg = 8 × 105 × 0.8 × 0.24 N-m = \(\cfrac{8\times10^5\times0.8\times0.24}{10^3}\) = 153.6 kJ. (ii) Internal latent heat = xhfg – external work done = 0.8 × 2046.5 – 153.6 = 1483.6 kJ. |
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