Calculating the maximum temperature of a heating wire

In summary, the conversation is about a question regarding a hair dryer and the maximum temperature of its heating wire. The hair dryer is described as a cylinder with a fan inside and a nichrome wire that heats up at different power settings. The given information includes the temperature environment, voltage, and dimensions of the cylinder and wire. The participants of the conversation discuss different approaches to solve the question, including looking up the heat transfer coefficient for a cylinder with transverse flow. However, it is mentioned that the question may be too difficult to answer without further information or calculations.
  • #1
Komberly
<mod: moved from intro>

Hello all! This is my first post in this forum. I am struggling with the following question regarding a hair dryer. The hairdryer can be seen as a cilinder with a fan inside blowing air at speeds from the table below and 1 nichrome wire which heats up consuming different amounts of power per setting on the fan. The air is approximately blown from a perpendicular direction onto the wire.

Given information:

DcKa6sxHhRkJ50O_J1-jWABmZmxuvdJDReX390LQUuH0nKvad6BvvGg3fd6Jove_5dCodRAzfS5UprutuGrU-sh1HwjCoWLt.png

Fig. 1

Temperature environment = 20 degrees C
Ugrid = 230V
Dcilinder = 38mm
Lwire = 55mm
Dwire = 0,5mm

The question is: What is the maximum temperature of the heating wire?

Who can help me out? Many thanks in advance,

Komberly
 
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  • #2
Welcome to the PF. :smile:
Komberly said:
The question is: What is the maximum temperature of the heating wire?
You need to show us what the Relevant Equations are, and show us your Attempt at the Solution. We need to see your work before we can be of tutorial help.

Also, I'm not sure that enough information is presented to try to figure out the temperature of the wire, but maybe it is. Seeing the Relevant Equations that you will post should help in deciding that...
 
  • #3
Hello Komberly, :welcome:

Perhaps you can see the wire glow in setting III ? Then you know it is a lot hotter than the air coming out.

An approach could be that you look up the heat transfer coefficient for a cylinder with transverse (or cross-) flow like here, here or here, but I suspect you are asking a question that is way too difficult to answer for you ...
 
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Likes berkeman

1. What is the formula for calculating the maximum temperature of a heating wire?

The formula for calculating the maximum temperature of a heating wire is: T = (P x R) + T0, where T is the maximum temperature in Kelvin, P is the power input in watts, R is the resistance of the wire in ohms, and T0 is the initial temperature of the wire in Kelvin.

2. How does the length and thickness of the wire affect the maximum temperature?

The length and thickness of the wire can affect the maximum temperature by changing the resistance of the wire. A longer and thinner wire will have a higher resistance, leading to a lower maximum temperature. A shorter and thicker wire will have a lower resistance, resulting in a higher maximum temperature.

3. What is the relationship between the voltage and the maximum temperature of the heating wire?

The maximum temperature of a heating wire is directly proportional to the voltage. This means that as the voltage increases, the maximum temperature will also increase, and vice versa.

4. How does the type of material used for the heating wire impact the maximum temperature?

The type of material used for the heating wire can greatly impact the maximum temperature. Different materials have different resistivity values, which can affect the resistance of the wire. Materials with higher resistivity will have a lower maximum temperature, while materials with lower resistivity will have a higher maximum temperature.

5. Is there a limit to the maximum temperature that a heating wire can reach?

Yes, there is a limit to the maximum temperature that a heating wire can reach. This is determined by the melting point of the material used for the wire. If the temperature exceeds the melting point, the wire will melt and no longer function as a heating element.

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