# Calculating the maximum temperature of a heating wire

#### 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:

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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#### berkeman

Mentor
Welcome to the PF.
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...

#### BvU

Homework Helper
Hello Komberly,

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 ...

"Calculating the maximum temperature of a heating wire"

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