Efficiency of heating up aluminum vs steel by induction

In summary: Haha, what I meant to write was: "The surprising thing about the result of the lab was that according to our measurements, the efficiency of aluminum was more than twice as high as the efficiency of...
  • #1
Karl Karlsson
104
12
Summary: In a heating by induction experiment performed, the idea was to determine the efficiency of heating up a small steel cylinder, an aluminum cylinder and then compare the two efficiencies. The cylinder was surrounded by a metall coil that alternating current was going through, alternating with the resonance frequency. The surprising thing about the result of the lab was that according to our measurements, the efficiency of aluminum was more than twice as high as the efficiency of aluminum.

In a heating by induction experiment performed, the idea was to determine the efficiency of heating up a small steel cylinder, an aluminum cylinder and then compare the two efficiencies. The cylinder was surrounded by a metall coil that was connected to a power supply which generated an alternating current, alternating with the resonance frequency for the materials. The surprising thing about the result of the lab was that according to our measurements, the heating efficiency for aluminum (about 20%) was more than twice as high as the heating efficiency for steel (about 10%). Due to the steel cylinder used being a ferromagnetic (higher permeability?) material, should not the heating efficiency for steel be higher than that of aluminum?
 
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  • #2
Karl Karlsson said:
The surprising thing about the result of the lab was that according to our measurements, the efficiency of aluminum was more than twice as high as the efficiency of aluminum.
Wow, that really is surprising! o0)
 
  • #3
Karl Karlsson said:
according to our measurements
Please explain what measurements were taken and how you calculated the efficiencies.
 
  • #4
berkeman said:
Wow, that really is surprising! o0)

Good that I am not the only one who thinks that! Do you know why? Of course there are sources of error, but that big of a difference in efficiency makes me doubt that it is the reason
 
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  • #5
haruspex said:
Please explain what measurements were taken and how you calculated the efficiencies.

The specific heat capacities for the volumes of the cylinders of the different materials were given and the power was set to be about 20W which i got by adjusting the voltage and current from the power supply. The efficiency is equal to: μ = c*V*ΔT/(Δt*I*U), the volume was exactly the same for all the cylinders, U*I is the avarage effect from the power supply, c is the specific heat capacities for the different materials (with the unit J/(K*m^3)). From steel I got the efficiency to about c*V*ΔT/(Δt*I*U)=0.1, using a power of almost U*I=20W, whereas for aluminum i got the efficiency to about 0.2 also using a power of almost 20W. What could be the reason fot this?
 
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  • #6
Karl Karlsson said:
Good that I am not the only one who thinks that! Do you know why? Of course there are sources of error, but that big of a difference in efficiency makes me doubt that it is the reason
You missed the sarcasm. Read carefully your text as quoted in post #2.
 
  • #7
Karl Karlsson said:
The specific heat capacities for the volumes of the cylinders of the different materials were given and the power was set to be about 20W which i got by adjusting the voltage and current from the power supply. The efficiency is equal to: μ = c*V*ΔT/(Δt*I*U), the volume was exactly the same for all the cylinders, U*I is the avarage effect from the power supply, c is the specific heat capacities for the different materials (with the unit J/(K*m^3)). From steel I got the efficiency to about c*V*ΔT/(Δt*I*U)=0.1, using a power of almost U*I=20W, whereas for aluminum i got the efficiency to about 0.2 also using a power of almost 20W. What could be the reason fot this?
Nothing jumps out, but take a look at https://en.m.wikipedia.org/wiki/Induction_heating#Details. Maybe the frequency was not high enough for the a/d ratio.
 
  • #8
haruspex said:
Nothing jumps out, but take a look at https://en.m.wikipedia.org/wiki/Induction_heating#Details. Maybe the frequency was not high enough for the a/d ratio.
They are calculating reference depth in centimetres in the linked wikipedia page so i will do that as well.I have already checked that but using that formula gives considering:Relative depth d = 5000*(ρ/(μ*f))^(1/2)
diameter, a=10^(-2)m

Steel:
Resistivity: 6.9*10^(-9)Ω*cm
Relative permeability: 100
Frequency: 118000Hz
a/d=8271

Aluminum:
Resistivity: 2.65*10^(-10)Ω*cm
Relative permeability: 5000
Frequency: 116000Hz
a/d=4184The ratio relative depth divide by diameter is higher for steel and should therefore have higher efficiency, right?
 
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  • #9
Karl Karlsson said:
Good that I am not the only one who thinks that!
Did you read the text of yours that I quoted...? :wink:
 
  • #10
berkeman said:
Did you read the text of yours that I quoted...? :wink:
Haha, what I meant to write was: "The surprising thing about the result of the lab was that according to our measurements, the efficiency of aluminum was more than twice as high as the efficiency of steel."
 
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1. What is the difference in efficiency between heating up aluminum and steel by induction?

The efficiency of heating up aluminum and steel by induction depends on several factors such as the type and thickness of the material, the induction heating equipment used, and the desired heating temperature. Generally, aluminum has a higher electrical resistance compared to steel, making it less efficient to heat up by induction. However, with the right equipment and settings, both aluminum and steel can achieve high levels of efficiency.

2. How does the type of induction heating equipment affect the efficiency of heating up aluminum and steel?

The type of induction heating equipment used can greatly impact the efficiency of heating up aluminum and steel. For example, solid-state induction heating equipment is more efficient compared to tube-style equipment. This is because solid-state equipment can provide more precise and uniform heating, resulting in less energy waste and higher efficiency. Additionally, equipment with advanced features such as automatic frequency tuning can further improve efficiency.

3. What is the role of material thickness in the efficiency of heating up aluminum and steel by induction?

The material thickness plays a crucial role in the efficiency of heating up aluminum and steel by induction. Thicker materials require more energy to heat up, resulting in lower efficiency. This is because the energy needs to penetrate through a larger mass of material. It is generally more efficient to heat up thinner materials as the energy can reach the desired temperature faster and with less energy waste.

4. Can the desired heating temperature affect the efficiency of induction heating for aluminum and steel?

Yes, the desired heating temperature can affect the efficiency of induction heating for aluminum and steel. The higher the heating temperature, the more energy is required to reach it. This can result in lower efficiency, especially for thicker materials. It is important to carefully consider the heating temperature needed for the application and use the appropriate equipment and settings to achieve the desired efficiency.

5. How can induction heating efficiency be improved for both aluminum and steel?

To improve induction heating efficiency for both aluminum and steel, it is important to use the right equipment and settings for the specific material and application. This includes selecting the appropriate frequency, power, and heating time. Additionally, proper insulation and temperature control can also contribute to higher efficiency. Regular maintenance and calibration of the equipment can also help ensure optimal efficiency in the long run.

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