In a chemical plant, a certain chemical is heated by hot water supplied by a natural gas furnace. The hot water (Cp = 4180 J/kg.°C) is then discharged at 60 °C at a rate of 8 kg/min. The plant operates 8 h a day, 5 days a week, 52 weeks a year. The furnace has an efficiency of 78 percent, and the cost of the natural gas is $0.54 per therm (1 therm = 100,000 Btu = 105,500 kJ). The average temperature of the %3D %3D cold water entering the furnace throughout the year is 14 °C. In order to save energy, it is proposed to install a water-to-water heat exchanger to preheat the incoming cold water by the drained hot water. Assuming that the heat exchanger will re-cover 72 percent of the available heat in the hot water, deter- mine the heat transfer rating of the heat exchanger that needs to be purchased and suggest a suitable type. Also, determine the amount of money this heat exchanger will save the company per year from natural gas savings.

In a chemical plant, a certain chemical is heated by hot water supplied by a natural gas furnace. The hot water (Cp = 4180 J/kg.°C) is then discharged at 60 °C at a rate of 8 kg/min. The plant operates 8 h a day, 5 days a week, 52 weeks a year. The furnace has an efficiency of 78 percent, and the cost of the natural gas is $0.54 per therm (1 therm = 100,000 Btu = 105,500 kJ). The average temperature of the %3D %3D cold water entering the furnace throughout the year is 14 °C. In order to save energy, it is proposed to install a water-to-water heat exchanger to preheat the incoming cold water by the drained hot water. Assuming that the heat exchanger will re-cover 72 percent of the available heat in the hot water, deter- mine the heat transfer rating of the heat exchanger that needs to be purchased and suggest a suitable type. Also, determine the amount of money this heat exchanger will save the company per year from natural gas savings.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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