How do I calculate WORK for material I've mixed in a blender?
How do I calculate WORK for material I've mixed in a blender?
(OP)
I am mixing 500kg of a granola mix in a horizontal blender. I want to know how to calculate WORK in terms of kilowatts/kg or some units very close to that. I've collected kW of energy throughout the mixing cycle. I have the total cycle time and the total amount in kilograms that was mixed. Example: 7.19 total kW used over 14.33 minutes for a 500kg batch. How much WORK did I put into the 500kg batch? Thanks for your help.





RE: How do I calculate WORK for material I've mixed in a blender?
RE: How do I calculate WORK for material I've mixed in a blender?
You can calculate this answer by first determining the amount of electrical energy that was required for your process. You stated that you used 7.19 kW over a time period of 14.33 minutes. Since 1 kW = 1 kJ/s (where the J stands for Joules, an SI unit of energy), and 14.33 minutes = 859.8 seconds, you can determine the energy used by taking the ratyio of these two quantities.
Energy expended = Power*Time
= (7.19 kJ/s)*(859.8 s)
= 6182 kJ
Divide this result by the mass of the batch that was processed to get the final result.
Energy expended per unit mass = 6182 kJ/500 kg
= 12.4 kJ/kg
Maui
RE: How do I calculate WORK for material I've mixed in a blender?
RE: How do I calculate WORK for material I've mixed in a blender?
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How do I calculate WORK for material I've mixed in a blender?
If you try to extrapolate the work per kg of granola very far from the 500kg test point your data may get skewed. This would be due to the efficiency of the mixer drive and work required to spin the mixer empty.
For example if you were to mix 1kg of granola in a mixer capable of mixing 500kg batches it would take a very large amount of work per kg.
Barry1961
RE: How do I calculate WORK for material I've mixed in a blender?
However...
If there is no appreciable temperatuare increase of the granola durring the mixing process, I believe that the answer to the question you asked is zero.
Energy is the potential to do work, or conversely, if you do work on somthing, you increase its energy state.
It seems apparent that mixed granola has no more potential to do work than un-mixed granola components.
RE: How do I calculate WORK for material I've mixed in a blender?
RE: How do I calculate WORK for material I've mixed in a blender?
When I read a sentence "I collected KW of energy through the mixing cycle" I'm not certain what was collected. One can make some assumptions and do some math but it may be "garbage in, garbage out."
I pay for electricity in kilowatt-hours. It may be an unnecessary unit of energy but then so would another dozen or so units of work/energy if that is the rule.
Units base on names are usually capitalized as in Newton and Joule.
RE: How do I calculate WORK for material I've mixed in a blender?
RE: How do I calculate WORK for material I've mixed in a blender?
RE: How do I calculate WORK for material I've mixed in a blender?
sreid,
Your last post brings more confusion because K is for kelvin and j is nothing in SI. Kilojoules divided by kilograms is kJ/kg. More information regarding SI and its use can be found in the documents published by the National Institute for Science and Technology (NIST):
http://ts.nist.gov/ts/htdocs/200/202/mpo_pubs.htm
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How do I calculate WORK for material I've mixed in a blender?
Consequently, we have a problem to solve on where the energy is used.
The motor rating is no good since we dont know if it is partially or fully loaded. But we could measure the full load current during operation. The energy used would vary depending on the loading..(ie it would be a high initial load which would fall as the granola (whatever that is) was munched into pieces. So a graph could be produced.
However the mixer would generate noise and the granola would also rise in temperature (we are breaking molecular bonds which has an energy implication). Plus there would be friction generated by movement. At the same time, the mixer is not perfectly insulated so heat would be lost simultaneously.
So the answer is, yes you can measure it, but which bit are you interested in..the energy going into the food, the noise energy, the electrical energy used or what??
Friar Tuck of Sherwood
RE: How do I calculate WORK for material I've mixed in a blender?
Thank you for always being there to help elucidate the membership on SI. I for one appreciate it.
Best regards,
Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How do I calculate WORK for material I've mixed in a blender?
Is the granola the cinnamon brown sugar kind? 'cause I like that stuff.