Jump to content
kartik

heat transfer

Recommended Posts

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.

Share this post


Link to post
Share on other sites
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.

Do you want to give us any more information?

Share this post


Link to post
Share on other sites
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

 

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
!

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.

 

Share this post


Link to post
Share on other sites
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? 

This is the final problem you were asking about. 

thankyou!

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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.

 

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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.

Thanks for your answer. Couple of questions though:

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?

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.