Ice Bank Tank Coil Design

[kamilmohammed]

Hi all
I am new to RE and need your help.

For an ice bank tank, the refrigeration load is 23.68 kW at -2 Deg C evaporating temperature (and 40 Deg C condensing temperature):

1. Can someone tell me the ideal diameter and length of copper pipe coil to be used as the evaporator for the system? The compressor manual indicates suction line of size 1 1/8" (ie., 22 mm).

2. If the cold water flow rate required for the application is 3000 litres per hour, what is the ideal volume of the ice bank tank required?

3. It would also be helpful if someone can actually give the general formula for coil design based on refrigeration load, involving the diameter and length of copper pipe (or based on surface area).

Regards
Kamil Mohammed.

[RANGER1]

For an ice bank you might want to have a lower evap temp than -2 deg C .
Maybe -15 deg C would be more productive .
You would also have to allow for ice build up while also having good water flow .
Pires would have to be well supported .
Unless you are really inquiring about chilled water ?

[kamilmohammed]

Dear Ranger,
Thanks for your reply. As you have rightly said, I do mean chill water tank. That is why -2 evaporating temperature. In our place, we wrongly call it Ice Bank Tank and I have noticed it only now. Could you help further?

[RANGER1]

I can't advise on tube sizes or lenths , but an easy way is to buy a evaporator coil block with wide as you can get fin spacing and put it in the water to be chilled .
Make sure there is good water circulation and maybe instal a second circulating pump to circulate in tank as well .
Or a spa air pump and pipe it up to a header in bottom of tank with lots of holes for air to stir everything up .
A stainless fin evaporator would be perfect .

[Peter_1]

Hi all
I am new to RE and need your help.
For an ice bank tank, the refrigeration load is 23.68 kW at -2 Deg C evaporating temperature (and 40 Deg C condensing temperature):
1. Can someone tell me the ideal diameter and length of copper pipe coil to be used as the evaporator for the system? The compressor manual indicates suction line of size 1 1/8" (ie., 22 mm).
2. If the cold water flow rate required for the application is 3000 litres per hour, what is the ideal volume of the ice bank tank required?
3. It would also be helpful if someone can actually give the general formula for coil design based on refrigeration load, involving the diameter and length of copper pipe (or based on surface area).
..

Hello, welcome to this forum.
1. Ideal? You just must make that your speed is enough to return oil. Feed from top to bottom so that it drains automatically. The dimension of the compressor valve doesn't say anything about the right size of the suction.
What refrigerant will you use.
2. Ideal volume? You even don't need a volume if you install a PHE coupled to a cooling machine which can handle 24 kW. You only need a reservoir if your compressor is smaller than your load. It depends how much smaller yoy will choose your compressor. But the idea of an ice bank of Ranger is very good, especially if you need chilled water
3. There is no such a formula, this will be trial and error. I posted on this forum a very old (+/- 1950) sheet from Kelvinator with capacities versus length and diameter
A good moment and exercise to use the serach feature of this forum.

[K.R.Iyer]

Kamil,

Is this for milk cooling? Ice Bank Tanks (IBT) are very popular in India for milk cooling application.

Pay adequate attention to have enough space for water to circulate over "ice built on tubes". Allowing ice to melt is the key to have required outlet water temperature.

Many IBT end up with ice sheets which will be difficult to melt and the outlet water temperature won't be low as required.

[kamilmohammed]

Dear Mr Iyer
Thanks for your post. I am from India too. As I have mentioned before, I mean an application for chilling and circulation of water by immersing copper coil in a water tank. To my knowledge, ice is formed only as a thin layer on the copper pipes(since evaporating temperature is -2 Deg C), which gets melted upon slight increase in load.

It is for cooling of ice cream mix during pasteurisation and subsequently during ageing.

[Peter_1]

Dear Mr Iyer
Thanks for your post. I am from India too. As I have mentioned before, I mean an application for chilling and circulation of water by immersing copper coil in a water tank. To my knowledge, ice is formed only as a thin layer on the copper pipes(since evaporating temperature is -2 Deg C), which gets melted upon slight increase in load.

It is for cooling of ice cream mix during pasteurisation and subsequently during ageing.

Well, for this process it's ideal to build up some ice. I have at least 4 clients who use an ice accumulator for pasteurization.
From your country: http://www.indiamart.com/cosmicrefri...equipment.html

[amitsaxena]

Dear Mr. Kamil, Can you send me more details of your system, so that i can design evap for your system.

Thanks
Amit Saxena

[kamilmohammed]

Dear Mr Amit
Thanks for your reply. I get the feeling that you might have the answers that I am looking for.

Well to explain in detail, we need to cool 1000 litres of ice cream mix per hour(maximum 6000 litres per day) from about 75 Deg C to 4 Deg C using a double section PHE(not a brazed PHE but a PHE with cooling tower water / chill water on one side and ice cream mix on another side). The first section will bring down the mix temperature from 75 to about 40 Deg C using cooling tower water. The second section will bring down the temperature from 40 to 4 Deg C using chilled water. It is for the second section that I need the chill water tank. Please also note that the same chill water will be used to circulate inside the jacket of 3 ageing vats, in which the cooled mix would be stored (maintained at about 4 Deg C under slow agitation) for 8 to 10 hours before actual use(the heat load for this purpose as you would find out, is negligible).

As per my calculations the maximum heat load required is about 39.4 kW at -2 evaporation temperature. I have chosen 2 BOCK water cooled condensing units(Model number : HGX34P/380-4) that deliver 23.68 kW each at -2 Deg C evaporation temperature and 40 Deg C condensing temperature. Now I need a set of suitable evaporation coils for the same.

Hope the above is clear to you.

[amitsaxena]

Dear Kamil,

WHat i got from the above mail is as,

You are having two different chambers one which will cool the desired load from 75°C to 40°C with the help of water coming from Cooling tower.

The second will furthur cool the load from 40°C to 4°C with the help of water (which is cooled by the second unit).
Your EVa. temp will be -2°C and cond. temp will be 40°C.

i am unable to get what for you are using first unit if you have cooling tower which can supply water at 45°C.

Also the bare coil length for cooling water in the chambers is required to provide required cooling capa.
Means you will dip that coil in the form of rectangular spiral and will solve the pupose.

Please mention the Refrigerant???
Correct me if i m wrong

Thanks
Amit

[kamilmohammed]

Dear Amit

It is not actually 2 chambers but 2 PHEs. And I need to cool ice cream mix not water.

A PHE, as you might be aware, consists of plates in which a cooling media (in our case cooling tower water in the 1st stage and chilled water in the 2nd) flows on on side of the plate and the product to be cooled (Ice cream mix) flows on the other side of the plate.

The heat from the product is absorbed by the cooling media thus facilitating heat transfer. It is for this circulation purpose that cooling tower water is used in the 1st stage and water chilled in a separate tank is used in the second stage.

You have rightly said :
"Means you will dip that coil in the form of rectangular spiral and will solve the pupose."

Refrigerant is R404A.

Hope it is clear now?

[benny_bronko]

how big of condensing unit do u plan to use? and its 5/8 od copper that u will need to use

[Rayin]

Dear Mr. Kamil Mohammed,
I tried to post a word document in regrads to evaporator coil designing. But as it is 1.23 MB in size, I couldn't. I don't remember from which site I downloaded it. If you send me the email ID, I can send it to you.
You may find some useful articles at the following website also http://www.nzifst.org.nz/unitoperations/httrapps3.htm

Regards
Rayin

[Peter_1]

Rayin, can't you post it on an external server like www.megaupload.com. Others then also can use it.

[Rayin]

Dear Peter_1,
I am more than happy to share it with all. But I don't know if I can upload it there. As I said, I downloaded it from the web. Do I need permission from the author to upload it on www.megaupload.com ?
Regards
Rayin

[Peter_1]

As you found it on the web, you don't need a permission to post it there. It remains also hidden on Megaupload till someone downloads it.

[Rayin]

It is done!!
http://www.megaupload.com/?d=DERAIFW4