Please Help!!! 1

[adeezy14]

Hello everyone,

I was hoping I could get some help with a project I'm making. I was wondering what components I would need to create a circuit that could heat polyurethane glass to a temperature of about 200-250 degrees. Ideally I would like the power source to be a small battery and have a switch that makes the circuit hot. I was wondering what size battery, what type of wire and the wire size, and how to construct the switch. I'm sorry I don't have any knowledge on the subject but was hoping someone might be able to give me an idea on how to begin. Thank you all and I hope to get some positive feedback.

 

[Skogsgurra]

You need to supply a little more information: Dimensions of glass and how fast you need to heat it are the more important parameters. I seriously doubt that you can use a battery. Why not think about gas - or a mains connected device? If you really need batteries, you will probably have to use lead acid (car) batteries. All other types have very limited power and energy contents.

Gunnar Englund

http://www.gke.org

 

[itsmoked]

polyurethane glass??? What is that? Polyurathane with glass fibers in it?

 

[adeezy14]

Thank you for responding. A little more information, the glass would be approximately 2mm. Polyurathane glass is used in cooking if I'm not mistaken. How much Voltage do you think would be required to heat that glass? I'm sorry I'm not that knowledgable on the subject. I appreciate any and all help.

 

[IRstuff]

You are indeed mistaken. Polyurethane is essentially a plastic and has nothing whatsoever to do with glass.

Perhaps you were thinking of Pyrex? However, Pyrex is non-conductive, so it's completely unclear how you think your "circuit" is going to work.

TTFN

 

[itsmoked]

Glass used in cooking is usually Pyrex it has a melting point of 1,509.8F; 821C.

You need to give us a much bigger, clearer picture of what exactly you want to achieve.

 

[rjgoebel]

Adeezy,
My first concern first of all is using battery power. In general, heating things using a battery uses a lot of power and drains the battery exceptionally fast. I was looking into using batteries to simply power some resistive elements that would go in a jacket or boots, to make it so that you could be warm while you do work, and the batteries would not last long at all - a maximum lifetime no more than 3 hours for something like this.

Heat simply takes a ton of power. Tell us more about what you want to do, and why you can't use an AC power outlet to power whatever it is you want to build. An electric skillet/bowl? I'm intrigued.

Jim Goebel,
Electrical Engineer
Mid-West Forensics, Inc.

 

[jsolar]

Whatever it is you are heating, you will need to know its specific heat (you have already given the volume as 2mm, so is that a 8 cubic mm?). Then you will need to explain to us the method of conduction and efficiency into this material. With unfounded assumptions on the specific heat and on the ability to insulate your sample to heat from conducting I think you could indeed bring the temperature up to 250 degrees C once with a battery smaller than a car battery.

For example, a coffee maker can heat 1,750 cubic mm of water up by 40 degrees C with about a half a million Joules assuming an 85% efficiency. Assuming your material heats up 4X faster (easier from the specific heat) than water and your sample size is 220 times smaller and you need to go 5X as far (200 degree C change instead of only 40) you might assume it takes 3000 Joules to get there. If a C-cell can store 10 Watt-hours (36,000 Joules), you should be able to build a device that heats up a very small sample and maintains a temperature of 250 degrees C a few times before the battery is empty.

Best Regards,
John Solar

 

[nbucska]

IRSTUFF:
Glass is a container to drink a liquid from, may be made
of glass ( atransparent silicate ) or any number of plastic.


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[Skogsgurra]

Given the incompleteness of the OP, the lack of awareness of engineering methodology, the fact that it is "a project I'm making" and the overall naïvity shining through, I cannot help thinking that we are trying to help a student again.

Do we never learn...?

Gunnar Englund

http://www.gke.org

 

[adeezy14]

First of all I assure you I am no student. Secondarily my vague OP was meant more because I had some basic questions. Now, I know I am naive on all things electrical (Thanks Gunnar for pointing that one out) so I appreciate your help. So, the feasibility of making a small portable source of power to heat up a relatively small sample the size of say a nickel, is impossible or just impractical?

 

[tuned99]

Is the temperature requirement in Fahrenheit or Celsius & how long does the sample need to be heated for?

 

[itsmoked]

I just designed a product for terminating fiber optics. It is essentially an oven you could fit a pen 3/4" into. A cylinder. It heats the inside of this cylinder to 150C in 1 minute and keeps it at that temp for 4 minutes. This was not easy to do! A large Gelcell of the 7A-HR size about 10lbs did this cycle about 100 times in about eight hours.

Here we are talking about one thousand, five hundred degrees!

I would expect this task to take about 100AHrs for one cycle... That's a lead acid battery that takes two strong men to barely move.

 

[Skogsgurra]

Not to thank for. A natural observation only.


Now. Give us these facts:

1 Describe what you want to do. Is it to sterilize, analyze, process, or what?

2 Is it a piece of glass or polyurethane that we are talking about?

3 What are the dimensions? I think you said "a nickel" would that be a circular disk around ten millimetres and 1.5 mm thick?

4 What shall the end temperature be?

5 How fast do you need to reach that temperature?

6 For how long shall the temperature be maintained?

7 Surrounding temperature?

8 Will there be any winds or will it be in still air?

9 How many of these devices are you going to make?

10 Are batteries your only option? Or can gas, alcohol or a mains connection be considered?

11 How bulky may such a device be? Give acceptable dimensions and weight.

12 What about cost? Is it a ten dollar device? Or hundred or thousand dollars? Or more?

13 Shall it be used only once or shall it have a certain life-time? If so, how long? Number of uses?

14 Any other pertinent input?

If you take your time and answer these questions, and add information that I haven't thought about asking, then I'm sure that someone in here will help you. But starting the way you did will make many people (me for instance) question the maturity of the OP - or if you have a homework that you want someone else to do.

Student postings are a constant concern in here. For very obvious reasons.

Gunnar Englund

http://www.gke.org

 

[itsmoked]

HERE! HERE! skogsqurra!

Well put my man!