4. Given a system of five (5) 3500-lb, 700 feet per minute (fpm) elevator cars. Gearless...

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Mechanical Engineering

4. Given a system of five (5) 3500-lb, 700 feet per minute (fpm)elevator cars. Gearless traction motors are being used for thissystem. Each car operates approximately 65% of the time and whilein operation, each car draws 96% of the full load. Calculate

a. Heat generated in the machine room during peak periods.Assume solid-state control is used. (5 points)

b. Assume the following operation profile during a 24-hourday

5 hours peak use

3 hours of 70% peak

4 hours of 50% peak

12 hours of 10% peak

Calculate the approximate monthly energy cost using theelectricity rate of $0.10/kWh assuming 25 days of operation percalendar month (10 points)

Answer & Explanation Solved by verified expert
3.8 Ratings (513 Votes)

Given that,

    E = 3500 x 700 = 24500000 ft lb/min = 56350 W

   Heat generated = W / V

   V = 0.96

   Heat generation = 56350 / 0.96 = 58697.9 W/m3

b) Given that,

    The working hours daily = 12 hrs

Energy consumption daily = 5365

   rate = $0.1 / Kwh

   25 days per month

Then the cost calculation = $2.02 / month

                                       = $24.68 / year.


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