WallaWalla
Bioengineer
- Oct 22, 2012
- 12
Hello everyone,
I'm carrying out a project which provides the cooling of a fluid inside a tube. In particular I should cool water or a glycolytic solution from a temperature of 25 °C to about 0 °C. I thought to do this through the use of the thermoelectric effect, then the Peltier cells.
I have two ideas. The first involves the use of a fluid reservoir and the cold face of the Peltier cells is in contact with the bottom of the container (figure). I thought I could get at the bottom not just one but multiple cells .
The second one is to use a system which is a kind of enclosure of the tube in which the fluid flows (figure).
I can give you some more information:
Case 1) deltaT = 25 °C -> 25 °C to about 0 °C
fluid volume / container -> 1 liter
container size -> might be 10 cm x 10 cm x10 cm
thick container -> 1mm steel
Calculating the heat subtracted from the volume of water: Q = 4186 * 1 * 25 = 104kJ. So if I want that the refrigeration is about 10 minutes I have to subtract cooling power of 104kJ/600s = 174W. Because of the dispersion may well need more than enough, say 200W (but it is a random number, I have not done any calculation).
With cells taken, for example, I run the following calculations: I took that model because one side is 47mm and the bottom of the container there are 4.
Their power is 72W and the maximum temperature difference of 74K, which means that for each kelvin of difference between the temperatures of the two faces is lost approximately 1W.
The thermal resistance of the steel wall is negligible.
4-cell 72W make 288W, 200W serve to us, means that we have 88W for the internal conduction of the cells, which means 22W per cell; then the maximum temperature difference between the two faces must be of approximately 22K.
Since the bottom of the container is at about 0C, the other face of the cells at the maximum can go to 22C. If the air is at 20C, I have a temperature difference of 2K to dissipate from the area to 1dm^2 a power equal to 4x (13.1Ax8.8V +50 W) = 660W.
Then I need a heatsink with thermal resistance of 2K/165W = 12mK / W for each cell. Or a single heatsink of 2K/660W = 3mK / W.
CALCULATION ARE RIGHT?
Case 2) flow -> 1l/min
deltaT = 25 ° C -> 25 ° C to about 0 ° C
wall thickness -> 0.1mm
In this case I would understand if it is possible and if the cooling depends on the length of the tube and such other factors.
I know that in the market there are some chillers that use the traditional refrigeration cycle but also the thermoelectric effect.
Also, if someone knew other methods to achieve my goal can tell me please.
Thank you to all, Emanuel
I'm carrying out a project which provides the cooling of a fluid inside a tube. In particular I should cool water or a glycolytic solution from a temperature of 25 °C to about 0 °C. I thought to do this through the use of the thermoelectric effect, then the Peltier cells.
I have two ideas. The first involves the use of a fluid reservoir and the cold face of the Peltier cells is in contact with the bottom of the container (figure). I thought I could get at the bottom not just one but multiple cells .
The second one is to use a system which is a kind of enclosure of the tube in which the fluid flows (figure).
I can give you some more information:
Case 1) deltaT = 25 °C -> 25 °C to about 0 °C
fluid volume / container -> 1 liter
container size -> might be 10 cm x 10 cm x10 cm
thick container -> 1mm steel
Calculating the heat subtracted from the volume of water: Q = 4186 * 1 * 25 = 104kJ. So if I want that the refrigeration is about 10 minutes I have to subtract cooling power of 104kJ/600s = 174W. Because of the dispersion may well need more than enough, say 200W (but it is a random number, I have not done any calculation).
With cells taken, for example, I run the following calculations: I took that model because one side is 47mm and the bottom of the container there are 4.
Their power is 72W and the maximum temperature difference of 74K, which means that for each kelvin of difference between the temperatures of the two faces is lost approximately 1W.
The thermal resistance of the steel wall is negligible.
4-cell 72W make 288W, 200W serve to us, means that we have 88W for the internal conduction of the cells, which means 22W per cell; then the maximum temperature difference between the two faces must be of approximately 22K.
Since the bottom of the container is at about 0C, the other face of the cells at the maximum can go to 22C. If the air is at 20C, I have a temperature difference of 2K to dissipate from the area to 1dm^2 a power equal to 4x (13.1Ax8.8V +50 W) = 660W.
Then I need a heatsink with thermal resistance of 2K/165W = 12mK / W for each cell. Or a single heatsink of 2K/660W = 3mK / W.
CALCULATION ARE RIGHT?
Case 2) flow -> 1l/min
deltaT = 25 ° C -> 25 ° C to about 0 ° C
wall thickness -> 0.1mm
In this case I would understand if it is possible and if the cooling depends on the length of the tube and such other factors.
I know that in the market there are some chillers that use the traditional refrigeration cycle but also the thermoelectric effect.
Also, if someone knew other methods to achieve my goal can tell me please.
Thank you to all, Emanuel
