Interested to Buy Any Domain ? << Click Here >> for more details...
Question 73 - (a) A dryer reduces the moisture content of 100 kg of a potato product from 80 % to 10 % moisture. Find the mass of the water removed in such drying process. (b) During the drying process, the air is cooled from 80°C to 71°C in passing through the dryer. If the latent heat of vaporization corresponding to a saturation temperature of 71°C is 2331 kJ / kg for water, find the heat energy required to evaporate the water only. (c) Assume potato enters at 24°C, which is also the ambient air temperature, and leaves at the same temperature as the exit air. The specific heat of potato is 3.43 kJ / (kg °C). Find the minimum heat energy required to raise the temperature of the potatoes. (d) 250 kg of steam at 70 kPa gauge is used to heat 49,800 cubic metre of air to 80°C, and the air is cooled to 71°C in passing through the dryer. If the latent heat of steam at 70 kPa gauge is 2283 kJ / kg, find the heat energy in steam. (e) Calculate the efficiency of the dryer based heat input and output, in drying air. Use the formula (Ti - To)/(Ti - Ta) where Ti is the inlet (high) air temperature into the dryer, To is the outlet air temperature from the dryer, and Ta is the ambient air temperature.
- 1 Answers
- 6133 Views
- I also Faced
- E-Mail Answers
Answer Posted / kang chuen tat (malaysia - pen
Answer 73 - (a) The mass of dried material is constant throughout the drying process, or 100 kg x 0.2 = 20 kg. Mass of water = mass of dried material (% of water / % of dried material). Initial mass of water = 20 (80 / 20) = 80 kg. Final mass of water = 20 (10 / 90) = 2.222 kg. Mass of the water removed = Final mass - Initial mass = 80 - 2.222 = 77.778 kg. (b) Heat energy required to evaporate the water only = Mass of the water removed x Latent heat of vaporization = 77.778 kg x 2331 kJ / kg = 181300.518 kJ. (c) Minimum heat energy required to raise the temperature of the potatoes = Mass of potatoes of 80 % moisture x specific heat of potato x temperature changes = 100 kg x 3.43 kJ / (kg °C) x (71 - 24) °C = 16121 kJ. (d) Heat energy in steam = mass of steam x latent heat of steam = 250 kg x 2283 kJ / kg = 570750 kJ. (e) Efficiency of the dryer based heat input and output = (Ti - To) / (Ti - Ta) = (80 – 71)/ (80 – 24) = 0.1607. The answer is given by Kang Chuen Tat; PO Box 6263, Dandenong, Victoria VIC 3175, Australia; SMS +61405421706; chuentat@hotmail.com; http://kangchuentat.wordpress.com.
| Is This Answer Correct ? | 7 Yes | 0 No |
Post New Answer View All Answers
Explain how can one estimate how the friction factor changes in heat exchanger tubes with a change in temperature?
What are the methods involved to test helium leak testing in a vacuum system?
Explain the different ways in which solids can be blended?
Is there any way to repair a valve that is passing leaking internally without taking our process offline?
hi can u send me all d technical qus pepar of DRDO?my email id is palmzk@gmail.com
hello everyone do anyone have interview questions for any chemical industry please email me at
sir, kindly explain to me that how to calculate volume of torrispherical vessel which is used in pharma company ss reactor bottom dish volume. thank u.
Why is post-weld heat treatment sometimes necessary for welded vessels?
How can one estimate how the friction factor changes in heat exchanger tubes with a change in temperature?
Explain what are the affinity laws associated with dynamics pumps?
What is the wet bulb globe temperature (wbgt)?
What is difference between overall heat transfer coefficient & individual heat transfer coefficient?
How to size the cooling tower sump / basin for any given circulation rate? What is the guideline?
based on percentage problems
What's -74C, dew point is better the -70C dew point In draying unit .
