Heating Elements for Experiments

[delta720]

Hi,

As part of my final year project I have to heat air within an exclosed environment (i.e. a 1m x 1m x 1m insulated box) to test the effectiveness of using phase change materials to regulate ambient air temperature.

To do this I need to slowly heat the air inside the box at a rate that will allow the walls (plasterboard) to increase in temperature roughly at the same rate as the air.


A similar experimant was done in my college several years ago and that student used a 200W light bulb, however it took around 12 hours to increase the temperature by 8 degrees, so there was clearly massive heat loss.

I've thought of using a low power fan heater but I think the fan blowing the hot air will result in the thermometers picking up a higher temperature then what the walls actually are. If i just use the heating element from the fan and allow convection currents to form in the box to slowly heat all the walls would this result in the element overheating and pose a fire risk?

Cheers,

Dave

 

[vk6kro]

The fan heater seems like a good idea, however there has to be an actual air flow. You can't blow air into a sealed box, so you need an exit for the air. This should be well away from the input, though.

The element of a fan heater is designed to have air flowing across it or it will overheat, as you mention. Try blocking the air flow and watch the element go red hot.

You can measure the air temperature at a place in the box which is not directly in the path of the air flow. This would be better if you cut the air flow from the fan heater for a minute or so before you take the measurement.

You can get probe thermometers which have a digital thermometer attached to a rigid rod which you can poke through a hole to measure temperature.
You could have several holes and keep records for each hole.

You can buy replacement elements for ovens but these require mains voltage, so you would need to get it wired up safely.

Blankets or pieces of carpeting will help insulate the box if you attach them to the outside of the box.

 

[BilPrestonEsq]

How about FOUR 200w light bulbs!

 

[vk6kro]

How about FOUR 200w light bulbs!

Maybe, but you would need some fans in there as well.

Just a suggestion, but, how would it go if you put the fan heater inside the box.

Then it would get air that was already heated and heat it some more as well as spreading it around the inside of the box.

You would have to monitor the temperature or it could become a fan forced oven and melt the plastic of the heater.

 

[DeeNos]

Hello Dave,

Thank you for sharing your project with me. Heating air within an enclosed environment can be a challenging task, especially when trying to regulate the temperature using phase change materials. It seems like you have already done some research and have some concerns about the heating element you plan to use.

In terms of heating elements, there are a few options you can consider. First, you may want to look into using a ceramic heating element instead of a light bulb or fan heater. Ceramic heating elements are designed to heat up quickly and evenly, making them a good option for your experiment. Additionally, they are often more energy efficient and have a longer lifespan compared to traditional heating elements.

Another option to consider is using a heating mat or tape. These can be placed on the walls of your insulated box and provide a more even distribution of heat compared to a single heating element. They also have the added benefit of being able to regulate the temperature more precisely.

As for your concern about the fan heater causing inaccurate temperature readings, you could try using a separate thermometer to monitor the air temperature and compare it to the readings from the fan heater. This can help you determine if the fan is causing any significant discrepancies.

In terms of fire risk, it is always important to take precautions when conducting experiments involving heat. Make sure to closely monitor the temperature and have a fire extinguisher nearby, just in case. You can also consider using a temperature controller to regulate the heat output and prevent the heating element from overheating.

I hope this information helps you in your project. Good luck with your experiments!