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Power requirement to drive a tumble dryer

02/26/2007 12:48 PM

I want to drive a tumble drum dryer @ 30 rpm with 60 kg of garments. What are the factors I need to take into consideration and how do we calculate the power requirement. The dryer would use a pulley mechanism to further reduce the speed from a gearbox connected to an electric motor.

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#1

Re: Power requirement to drive a tumble dryer

02/26/2007 12:57 PM

Well, we need a ton more information. Where are you, in the US most electric motors run 3600 rpm, (60Hz) and most anywhere else it's 3,000rpm, (50 Hz.) What size is your pully? What size in your drum?

My suggestion is to figure out what you need to acheive your 30 rpm, 120 to 1 reduction or 100 to 1? Then attack the problem of horsepower required for the 60 kg.

Good luck..

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#2
In reply to #1

Re: Power requirement to drive a tumble dryer

02/26/2007 1:53 PM

Thank you for the suggestion. The different parameters such as sizes of pulley, reduction ratio in the gear box, shaft diameter on drum, weight of drum can all be known and calculated. What other factors, besides the weight of the garments, we need to consider to rotate the drum in order to provide a torque on trhe drum.

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#3
In reply to #2

Re: Power requirement to drive a tumble dryer

02/27/2007 6:49 AM

I'd say that there's not too much except the weight of the load, the size of the drum, the resistance (atrict) of the drum, and the efficiency of your gearbox and transmission untill your motor shaft.

In the point of maximum load, you'd be dealing with your drum radius x 60 kg x 9.81 = "X" Nm of torque, at 30 rpm = Y power required at the device.

Multiply by the system losses coeficients, check some torque losses over time (bearing wear, ...) translate into a safety margin, and you got it.

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#4

Re: Power requirement to drive a tumble dryer

02/27/2007 7:23 AM
  1. Initially wet>- total load may be 90Kg
  2. Initially sticky>- might go uphill as a big packet and Drop and jerk and up and drop>>> time when you need maximum power. Design for this worst phase.
  3. Towards full dry, hardly any up>down>jerk>fall torque. No concern here -when #2 is already taken care of.

Worst Phase Power Requirement:

  • 30 rpm-- so, half turn=1second-- through which 90Kg rises 1 diameter high
  • We assume diameter 0.9m
  • Power=90x0.9Kg-m/second. Which will be almost 720 watt.=nearly 1HP
  • Most Induction Motors can take 2Xoverload torque.
  • You can get away with 1/2 HP.(Notify"Spin well before tumbling")
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