Ice stick: is a new HP technology or what?

[davidk]

Hello. I found a new type of heat pump, "ICE-STICK" type. I didn't heared until today about this technology.
I tried to post a link but the RE forum didn't allowed.
Anywhay, Octopus Energy AB produces this kind of HP's.
It's a new technolgy?
I can't understand how ice melts in order to form new ice, keeping in mind that the HP only works when ice si building up around the "sticks"

[Josip]

Hi, Davidk

Hello. I found a new type of heat pump, "ICE-STICK" type. I didn't heared until today about this technology.
I tried to post a link but the RE forum didn't allowed.
Anywhay, Octopus Energy AB produces this kind of HP's.
It's a new technolgy?
I can't understand how ice melts in order to form new ice, keeping in mind that the HP only works when ice si building up around the "sticks"

You have distributor in Romania maybe you can ask them about

http://www.octopus.tm/eng/af_rumanien.htm

For RE members link is here:
http://www.octopus.tm/eng/index.htm

Someone will explain how it works maybe with some sketch.

Best regards, Josip

[NoNickName]

It absorbs latent heat of condensation from the air moisture, and ice forms on the stick. The absorbed heat is then released in the heated space.

[Josip]

Hi, NoNickName

It absorbs latent heat of condensation from the air moisture, and ice forms on the stick. The absorbed heat is then released in the heated space.

It is true in that moisture is the biggest portion of heat and that is reason why A/C is expensive.

Do you mean outside air or waste air from house/office or both?

They want to use a lot of rejected heat(seems this is a point), but it is obvious a bigger part of heat must be taken from mother nature

Some Daikin VAM system use air to air heat exchangers, is this one the same type?

But, what happen when ice on stick is very thick and became an insulator-no heat exchange any more.

Do you have some idea what then?

Wait until sun will defrost that stick, meanwhile to use electric heaters, oil/gas heaters, etc...

Best regards, Josip

[davidk]

I'm not sure right now, but as I remember, 1kg of freezing water release 60...75W. So, running a 4kW evaporator continuously lead to 300kg of ice. I think I didn't considered the latent heat of condensing the moisture before freezing, which can give a considerably larger amount of heat.
Anywhay, even 10times less ice per kW, in one day, if it runs continuously, it requires to gather a large amount of ice. If outside temperature is below 0*C for several days, what happens? If outside temperature is low, let's say -10*C, the evaporating tempreature would be also low (not mentioning the very low amount of humidity in the air at these temperatures) and ice wouldn't fall from stick by itself. Is the Octopus the only producer of this kind of heatpump?

[NoNickName]

But, what happen when ice on stick is very thick and became an insulator-no heat exchange any more.

Do you have some idea what then?

The performance will fall, as with any other type of reverse-cycle heat pump. Especially, with no air forced circulation (the system is based on natural convection) the area surrounding the sticks will be colder.

[davidk]

I was thinking at a different type of heat pump somewhat similar to "ice stick":
A standard heatpump in which evaporator is made as a flat heat exchanger; a sprinkle system sprays water onto this flat evaporator area, placed in an almost level position. When compressor runs, the water is icing and the ice layer gets thicker. When the ice layer is thick enough (let's say 5cm, or 2 inches; a thicker ice layer would be like an insulator) the heatpump is reversed (deicing) but a very short time, because it doesn't need to melt ALL the ice; because of the almost level position of the evaporator, the ice is gliding and eventualy falls.
I think this kind would be very efficient in the very cold winters, when air heat pumps wouldn't work; in my case, the HP extracts the latent heat of the water that is sprayed and icing onto the evaporator.
Of course, after a long running time, a stack of ice appears under the evaporator.
But this would be feasable? Does this kind of system exists?

[NoNickName]

1) you need huge amount of water to be wasted
2) the surface of a flat area is very small, and as such the heat that can be exchanged very little. That's why coil surfaces are finned

No, I don't think it's feasible

[US Iceman]

I worked on some prototype systems for this almost 30 years ago. On our system we used vertical plates. After the ice was 3/8" thick, the defrost cycle was initiated to warm up the evaporator plates.

During this harvest cycle the water pump remained running so when the plates reached about 32F (0C) the ice sheet simply released from the evaporator plate and dropped into a tank below. The tank which held the ice also contained the spray water.

For all practical purposes it was an ice-maker heat pump. Some were sold for homes, others for office buildings.

These were used for both AC and heating. The ice was stored for the summer AC. During the summer the cold water was circulated to an air-cooling coil. During the winter or other seasons the heating was for domestic water heating or space heating.

[ernestlin]

It sounds a good method to economize the energy cost, but if those ice/water mixture can be preserved after several months? Even if, what's the size of the tank, it may be very big, and how to design the thermal blanket insulation? It may cost too much...Aboved points are personally.

[Lc_shi]

I searched Octopus website but found no clear information about its product lines. How about the performance of the ice-stick heat pump in comparison to air source or ground source heat pump? thanks in advance!

regards
LC