# heat transfer

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I have a 1x1x1 feet box.  I have a heating source in the box which produces "x" watts. How long will it take to increase the temperature of the box by 1 deg C?

thankyou.

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19 minutes ago, kartik said:

I have a 1x1x1 feet box.  I have a heating source in the box which produces "x" watts. How long will it take to increase the temperature of the box by 1 deg C?

thankyou.

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4 hours ago, kartik said:

I have a 1x1x1 feet box.  I have a heating source in the box which produces "x" watts. How long will it take to increase the temperature of the box by 1 deg C?

thankyou.

Assuming the box contains air and dimensions are the inside dimensions and ignoring losses the approximate energy required is...

Cv * Mass * temp = energy required

0.718 Kj/Kg-K * .034 kg * 1C = 0.024 kj or 0.00666 Wh

unless i made a math error

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8 hours ago, Bufofrog said:

Assuming the box contains air and dimensions are the inside dimensions and ignoring losses the approximate energy required is...

Cv * Mass * temp = energy required

0.718 Kj/Kg-K * .034 kg * 1C = 0.024 kj or 0.00666 Wh

unless i made a math error

okay, now how do we calculate the time required for this temperature rise if a constant energy of 0.024kj is produced?

thankyou.

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Is this going somewhere?  If so could you ask the final question so we can move along, or are just wondering about energy and heat transfer?

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Sounds like we are working our way through our homework questions.

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!

Moderator Note

Moved to Homework Help.

@kartik Please note that people may help you if you can show you have attempted to answer the question yourself. They are not here to do your homework for you.

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On 2/15/2020 at 8:17 PM, Bufofrog said:

Is this going somewhere?  If so could you ask the final question so we can move along, or are just wondering about energy and heat transfer?

I need to maintain the temperature in a small 1x1x1 ft chamber filled with just air at a certain value above the surrounding temperature of that chamber. what would be a suitable heating element and the insulating material for the chamber? how can i maintain a constant temperature? what are the factors i need to keep in mind for designing this chamber?

thankyou!

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Just a couple of questions, approximately what is this certain hold temperature and do you care about the heat up and cool down rate?

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21 hours ago, Bufofrog said:

Just a couple of questions, approximately what is this certain hold temperature and do you care about the heat up and cool down rate?

1.5 degree above the ambient temperature should be the temperature in the chamber at any given time with an error pf +- 5%.

since its a small box..if the temperature reaches the target value under a min, that woud be ideal. Please suggest a way.

Thankyou.

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The easiest way to do this is to go to Amazon and search for 'temperature controllers'.  There are many to choose from, you should be able to get one for about 30 dollars.  The heater can be a 10 watt heater or just a 10 watt light.  It will take a little trial and error to determine the best distance between the heater and sensor to maintain the temperature.  A well insulated box should decrease any temperature cycling.

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1 hour ago, Bufofrog said:

The easiest way to do this is to go to Amazon and search for 'temperature controllers'.  There are many to choose from, you should be able to get one for about 30 dollars.  The heater can be a 10 watt heater or just a 10 watt light.  It will take a little trial and error to determine the best distance between the heater and sensor to maintain the temperature.  A well insulated box should decrease any temperature cycling.

1. injecting heat into the system is easy. but if i have to somehow bring the temperature down, wont i need vents to do that? ( in scenarios where ambient temperature drops down drastically)

2. can i use nichrome wire as the heating element?

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