Is it possible to make a portable and compact
device which can cool the water (similar to the concept of immersion rod
which heats the water)? By: Shashi Poddar
Ya I think,based on peltier effect one can use it.There are some thermoelectric coolers I guess available too. But a simple experiment can be tried out. Take a glass of water.measure its temperature. As per knowledge I have , it works well if there are two dissimilar metals (preferable semiconductors) Then immerse one rod in glass of water and other outside and pass current. Lets see if temperature comes down.However its efficacy can be looked into.
Application wise But on smaller scale this can be used by poor people to cool water.Electricity can be used of solar cell. But in terms of price there may be a tradeoff. But still an experiment can be performed. I am ready for it :)
Peltier effect is a good option, but as far as i think, it can be used for bringing down the temperature of a object which is at a relatively higher temperature than the ambient temperature. In-order to bring down the temperature below the ambient, an extra work needs to be done, and the energy needs to be removed from the water. From what i understand, a physical process, which can absorb energy from the water is desired here.
I dont think that its has anything to do ambient temperature. You make a junction and one end will cool and other will heat up. And if one needs to absorb energy then we need to do some work.(simple thermodynamic law) and how to do that work is question or mystery. And ya peltiers will definitely be available in market but how to run them without battery or something or say use charge of human body to run. All these may be vague and their efficacy is definitely needs to tested, at least theoretically.
Why do you want to run them without battery..?? I believe that is not the problem... but to actually make it realizable... So keep the hot junction at room temperature.... And apply the voltage across the peltier with suitable polarity.... The heat will start flowing from cold to hot junction.... SO if we are able to cool down the hot junction via heat sink or air fan.... then the cold junction can be made freezingly cold.....:)
@Manjeet please explain a lil more. I am not able to get what exactly you are saying.
There is one more issue to this. Say as per peltier we get one hot and one cold junction. But if we are to cool water, then we will imerese one junction in water. But now its not only the peltier effect but also heat transfer that is playing a role. Now when a junction will be cooled down then water will give its heat to junction. similarly since at hot junction, temp is more than air it will lose heat. However, due to difference in heat transfer capacity of water and air (water being larger) there is possibility that the rate at which heat is given to cold junction may be far greater than rate at which heat is removed from hot junction. This may further cause reduction in temp. difference at junction and slowly reduce the cooling capacity. Or may be with time to maintain same cooling capacity the current needs to be increased as temp. at junctions is function of current/voltage (I suppose).
I agree to manjeet idea of providing heat sink and then fan etc which may increase heat transfer but this may make the system bulky. and also to run a fan is another issue.
But this seems to be a very good experiment which can be performed and tried out. What say??
Look Dude..... at any cost to low down the temp energy has to be removed.... lower the temp required... Larger is the energy required to be removed..... You have to do something to remove this heat.... A peltier can only transfer heat from one end to another.... that too via voltage application.. but the heat at other end has to be dissipated via any mean.... but heat has to be removed from hot junction... As keeping hot junction cooler will further Cool Down Cold Junction..thus drawing more energy from water.... So the only issue is how to remove this heat......Even ACs use fan motors uptill now to dissipate heat.. Other way is increasing the surface area..which you people are doing in HUD.. But that may not solve the problem...as We need to maintain HOt Junction at Average temp.. So as to make Cold Junction to Negative Range...
It is a Good Experimental Topic..... It will be good if we can have some material whose heat transfer coeffient towards air is very High... anything like that.....
Hey bigger dude, I did not clearly get what you are trying to say. Whatever I have understood is as follows. We need to remove/dissipate heat from hot junction so that more heat can be absorbed from water at cold junction. ryt?? If yes then I mentioned the same point few post ago. But here the problem of higher heat transfer coefficient came up. So it may be come that to remove heat from hot junction unnecessary work may have to be done.
And there is one conceptually wrong statement in your post. To remove certain amount of heat its not always you need to do higher amount of work. That is the basic principle of reverse carnot cycle or (refrigerators/heat pump). The work has to be done but needn't always be greater. However, in general what you said is true.(Though I have to look again from thermodynamics point of view. especially in terms of work done/heat gained/loss.)
Use this place to post your comments.
ReplyDeleteYa
ReplyDeleteI think,based on peltier effect one can use it.There are some thermoelectric coolers I guess available too.
But a simple experiment can be tried out.
Take a glass of water.measure its temperature.
As per knowledge I have , it works well if there are two dissimilar metals (preferable semiconductors)
Then immerse one rod in glass of water and other outside and pass current. Lets see if temperature comes down.However its efficacy can be looked into.
Application wise
But on smaller scale this can be used by poor people to cool water.Electricity can be used of solar cell. But in terms of price there may be a tradeoff.
But still an experiment can be performed. I am ready for it :)
Peltiers are available in the market...... but they are costly.... a single peltier cost around 1000 bucks...
ReplyDeletePeltier effect is a good option, but as far as i think, it can be used for bringing down the temperature of a object which is at a relatively higher temperature than the ambient temperature. In-order to bring down the temperature below the ambient, an extra work needs to be done, and the energy needs to be removed from the water. From what i understand, a physical process, which can absorb energy from the water is desired here.
ReplyDeleteI dont think that its has anything to do ambient temperature. You make a junction and one end will cool and other will heat up.
ReplyDeleteAnd if one needs to absorb energy then we need to do some work.(simple thermodynamic law) and how to do that work is question or mystery.
And ya peltiers will definitely be available in market but how to run them without battery or something or say use charge of human body to run.
All these may be vague and their efficacy is definitely needs to tested, at least theoretically.
Why do you want to run them without battery..??
ReplyDeleteI believe that is not the problem... but to actually make it realizable...
So keep the hot junction at room temperature.... And apply the voltage across the peltier with suitable polarity.... The heat will start flowing from cold to hot junction....
SO if we are able to cool down the hot junction via heat sink or air fan.... then the cold junction can be made freezingly cold.....:)
@Manjeet
ReplyDeleteplease explain a lil more. I am not able to get what exactly you are saying.
There is one more issue to this. Say as per peltier we get one hot and one cold junction. But if we are to cool water, then we will imerese one junction in water. But now its not only the peltier effect but also heat transfer that is playing a role.
Now when a junction will be cooled down then water will give its heat to junction. similarly since at hot junction, temp is more than air it will lose heat.
However, due to difference in heat transfer capacity of water and air (water being larger) there is possibility that the rate at which heat is given to cold junction may be far greater than rate at which heat is removed from hot junction.
This may further cause reduction in temp. difference at junction and slowly reduce the cooling capacity. Or may be with time to maintain same cooling capacity the current needs to be increased as temp. at junctions is function of current/voltage (I suppose).
I agree to manjeet idea of providing heat sink and then fan etc which may increase heat transfer but this may make the system bulky. and also to run a fan is another issue.
But this seems to be a very good experiment which can be performed and tried out.
What say??
Look Dude..... at any cost to low down the temp energy has to be removed.... lower the temp required... Larger is the energy required to be removed..... You have to do something to remove this heat.... A peltier can only transfer heat from one end to another.... that too via voltage application.. but the heat at other end has to be dissipated via any mean.... but heat has to be removed from hot junction... As keeping hot junction cooler will further Cool Down Cold Junction..thus drawing more energy from water....
ReplyDeleteSo the only issue is how to remove this heat......Even ACs use fan motors uptill now to dissipate heat.. Other way is increasing the surface area..which you people are doing in HUD.. But that may not solve the problem...as We need to maintain HOt Junction at Average temp.. So as to make Cold Junction to Negative Range...
It is a Good Experimental Topic.....
It will be good if we can have some material whose heat transfer coeffient towards air is very High... anything like that.....
Hey bigger dude,
ReplyDeleteI did not clearly get what you are trying to say. Whatever I have understood is as follows.
We need to remove/dissipate heat from hot junction so that more heat can be absorbed from water at cold junction. ryt??
If yes then I mentioned the same point few post ago.
But here the problem of higher heat transfer coefficient came up. So it may be come that to remove heat from hot junction unnecessary work may have to be done.
And there is one conceptually wrong statement in your post. To remove certain amount of heat its not always you need to do higher amount of work. That is the basic principle of reverse carnot cycle or (refrigerators/heat pump). The work has to be done but needn't always be greater.
However, in general what you said is true.(Though I have to look again from thermodynamics point of view. especially in terms of work done/heat gained/loss.)