Can I use peltier modules as a heater

[elahetal]

Hello everybody,
I am wondering how to use peltier module as a heater?
I have a Al block that I want to heat it up by putting the cod side of the peltier module on it. the other side is in floating in air(ambient). I am wondering which side is working as a reference for temperature. If I connect the peltier module to a power supply , by increasing the voltage, how the temperature varies in both sides? if I have temperature increase in one side and the floating side keeps the same temp as ambient temperature or both have increase and decrease in temperature?

Thanks for ur help

 

[crutschow]

Yes, you can use a peltier as a heater. It's similar to using a heat pump to heat a house. With a peltier, the cold side is just relative to the warm side. But note that the cold side may get cold enough to condense water or freeze. You likely will want to add a heat sink to the cold side to keep it from getting too cold. This also improves the efficiency of the hot side to generate more heat.

 

[elahetal]

Hello Carl,

Thanks a lot for your prompt response,

To make sure I got you correctly, could you please confirm my understanding?

I connect the peltier module to a power supply and place the one side on the AL block( that is supposed to be heated up) and then passing current through the modules makes that side warmer and the other side colder(than ambient temperature) relatively(temperature variation in both sides), and u suggest I use heatsink in cold side to avoid cold side becomes very cold, but I can not understand how a heatsink in cold side can avoid cold junction to become more colder?? could you please describe it for me.( I know heatsink is used to avoid going up of temperature in a component)

 

[Diver300]

A heatsink is almost always used to get rid of heat, or stopping something getting too hot. However, it is just as effective at getting rid of cold, or stopping something getting too cold.

A heatsink, or radiator, is just about increasing the amount of heat flowing, or reducing the temperature difference between something and the air around it.

On an air conditioning system, there are two heat exchangers, one inside the building, one outside. Each has lots of metal fins and a big fan. One heat exchanger increases the heat flowing into the air, the other increases the heat flowing out of the air.

Carl is absolutely right that a heatsink will keep the cold side of the peltier module warmer. It will always be colder than the air around it, but the difference will be less if there is a good heat exchanger.

If you want to try, find a big chunk of aluminium. Put an ice cube on it in a warm room. Put a similar size ice cube on a bit of wood. The one on the aluminium will melt first.

 

[elahetal]

Thanks Diver300, I got it what you and Carl mean.
Now, I am wondering if I do not care about the temperature difference between the two sides and just the produced power in warm side is of my interest,by adjusting the power supply voltage, can I estimate the amount of produced power in warm side using the peltier datasheet? Actually I want to control the power supply by my labview program and I need to know in the relation between applied voltage and dissipated power in warm side; sorry if my questions seems very trivial to you, I have never worked with peltier module and this is not my field.

 

[crutschow]

If you are interested in efficiency, then you need a heat sink on the cold side. The efficiency of a peltier junction depends upon the difference in temperature between the hot and cold sides (since the sides are not perfectly insulated from each other and heat will leak from the hot side to the cold side). If you look at the cooling curves for a peltier device you will see that it's efficiency is affected by the temperature difference.

You can use these curves of heat flow to determine how much additional heating the peltier will provide over just a resistive heater. (You add this heat flow to the heat already generated by the V x I of the peltier current).

 

[Sceadwian]

Sorry to bardge in, but heatsink issues aside is what's being said here than peltier modules don't actually have hot/cold sides it's only current direction that matters as far as which direction the heat goes, or is it generally more efficient one way than another because of the materials or construction?

 

[Oznog]

How hot do you want the hot side to be, and what temp should it operate in?

INITIALLY, with the "hot" side at room temp, the Peltier will pump heat out of the air through the cold sink and warm it up with substantially more wattage than the electrical power used. But, as the temp differential increases, the pumping efficiency declines. When the temp differential gets large enough, the thermal conduction through the Peltier itself will warm the cold sink and lose heat to the air, and it would have been more effective to simply use a resistor and place some insulation over it to keep it from losing any heat to the air.

And what actually determines the pumping efficiency is the temps at the hot and cold device faces. You need a big cold sink on the cold side to keep drawing in more heat from the air, if the plate gets cold (or freezes) then the pumping goes down to just about nothing.

 

[elahetal]

Thanks all for your response.

Dear Oznog,

I am going to heat up an AL block with a peltier module. In different part of my program, the temperature of the this block differs. For example once I need it goes up by 5 C and the other time 20 degree. According to the Block dimensions, my algorithm calculate the power needed for this issue and after that by adjusting the power supply across the peltier module, I want to apply this required power. I know that I have some power loss but I have a temperature controller loop that eventually will adjust the block temperature.

The maximum power I need goes high above the maximum power that is produced by the peltier module that I have chosen so probably it should works for about 3-5 minutes to provide the required watts for the block. The Qmax for peltier module is about 125W and the required watts in worst case is about 1000W.

what's your idea?

 

[Hero999]

I don't think the Peltier cooler is powerful enough.

A Peltier will reduce the power required to heat the block but you still need a powerful enough cooler to do it.

 

[elahetal]

I don't think the Peltier cooler is powerful enough.

A Peltier will reduce the power required to heat the block but you still need a powerful enough cooler to do it.

Thanks for your help.

Initially, I wanted to use power resistor for this issue but it doesn't work with instruments that I have in hand. so I went after peltier modules.

1) what do u mean from powerful enough cooler? u mean a peltier module with higher power?
2) if yes, what is your idea about using parallel peltier modules?

Thanks a lot

 

[Sceadwian]

Is anyone able to answer my question? Are commercially available peltier modules 100% bidirectional based on current, or is there a direction of heat flow that is more efficient?

 

[elahetal]

hey Guys,

Any idea about if peltier module works for my usage that I described above?

 

[Jerry O'Dell]

OK, question, What about using a peltier in a tank heater application for livestock water heater.
Idea I have in mind is a solar cell powering an inverter/battery combo which would then provide power to one or many Peltier modules mounted to stock tank used to water goats. Not the largest tank only about 10 goats however could you use the Peltiers to keep the water in the tank above freezing if the ambient temperature is 32 degrees F or below?

 

[Diver300]

A Peltier cell will provide somewhat more heat than a simple electric heater. How much more depends on how big the temperature difference is between the water and the source of heat.

**broken link removed**

That shows what you can expect. If the temperature difference is small, less than 20 °C difference, so above around 0 °F, and if you run the Peltier cells at low currents, you can probably get 2 - 3 times as much heat out as you would with a simple resistive heating element.

A downside is that you need a heat source, as described in post #2. At those temperatures, you run the risk of the heat source icing up. You might need to reverse the Peltier cell briefly every so often to warm the heat source above freezing to get any ice that has built up to fall off. Also the efficiency will reduce quite quickly as the outside temperature decreases.

The efficiency of a solar cell is very poor, and the coefficient of performance of a Peltier cell is not very good, so you will get far less heat than if you heated water directly from a solar panel, and stored the heat in a well insulated hot tank, something like this:-
https://www.apricus.com/html/solar_collector.htm#.VybiJiMrL-k

You can store far more energy in a water tank than in a lead-acid battery. A lead-acid battery is around 40 Wh/kg. Water at 70 °C has around 80 Wh/kg of heat compared to 0 °C, and a water tank that holds 250 kg of water is much cheaper than 250 kg of batteries.

If you store hot water you would need some thermostat and probably a pump to feed hot water to the tank that the goats drink from to keep their water at the right temperature without loosing all your heat quickly.

Whatever system you use, insulating what parts of the water tank that you can will reduce the heat loss that you need to make up.

 

[KeepItSimpleStupid]

No one really said what kind of temperature you need? Most Peltiers might be able to pull of a delta T between 40 and 60 C. Thats a given. There is a max T and and a max I. They are slow, inefficient devices. As pointed out, one side is better than the other.

If the surface goes below the dew point, you get condensation. In some applications, It's common to have one side at the temperature of ground water.

Modern Peltier controllers use PWM (Pulse Width Modulation).

You can also consider a water bath/circulator system that has both heating and cooling.

 

[ronv]

OK, question, What about using a peltier in a tank heater application for livestock water heater.
Idea I have in mind is a solar cell powering an inverter/battery combo which would then provide power to one or many Peltier modules mounted to stock tank used to water goats. Not the largest tank only about 10 goats however could you use the Peltiers to keep the water in the tank above freezing if the ambient temperature is 32 degrees F or below?

Hot is easy, it's cold that's hard.
Why don't you just use some immersion heaters?

 

[Anuj Prajapati]

Hello everyone,

I'm an intern at Indian Institute of Science, Bangalore and am currently developing a product which requires certain miniature heating devices that can evaporate a small drop of water.
The heating device has to be kept on continuously and should stay at a constant temperature of > 90 C.

Could you tell me about a commercially available or DIY heating device:
1) Which can stay at a temperature above 90 degree Celsius as long as it is powered.
2) Which is within the size of 4cm by 4 cm by 1 cm.
3) which can reach the max temperature in about 30-40 secs after being switched on.

I'm a little biased toward peltier devices, since I've plenty of them lying around in the lab.

Thanks, I'd be really grateful for your help.

 

[atferrari]

PWM driven ceramic resistor on a small aluminium plate. I used it as the plant in my first implementation of a PID control loop.

 

[PhysZe]

Hello!

I'm currently an intern at the Vilnius University Laser Research Center and I must develop a small dimension (aprox~40mmx60mmx5mm) sample heating/cooling system with a temperature range of -2ºC up to 150ºC for my setup. I was thinking of a single peltier element to achieve this temperature range, but, as I see from your answers, that might be a difficult and even impossible solution to my problem.

What made me think about a peltier device is the fact that I need something not too bulky and that can have a hole in its center (for sample backlighting purposes). Do you know any other solutions that may help me? (probably two different setups, one for heating - using resistors - and other for cooling?)

Thank you very much!