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Josip
05-04-2006, 10:33 PM
Hello,

please help me to find some more info regarding this article. Primary circuit will be with ammonia and secondary with glycol.

Any help is welcome,

Thanks,

Josip

US Iceman
05-04-2006, 11:19 PM
HI Josip,

Welcome back. We have not heard from you for some time. I hope all is well.

I looked for some information for you. I have provided several links below for each, onions and potatoes.

Onions
http://www.uga.edu/vegetable/onion.html

http://www.bae.ncsu.edu/programs/extension/publicat/postharv/ag-413-6/index.html

http://usna.usda.gov/hb66/099onion.pdf

Potatoes
http://vric.ucdavis.edu/veginfo/commodity/potato/potato_storage.pdf

http://www.uidaho.edu/ag/plantdisease/pstore.htm

http://www.uaf.edu/coop-ext/publications/freepubs/HGA-01024.pdf

http://www.agr.gov.sk.ca/docs/crops/horticulture/PotatoManual_StorageMngmnt.pdf

A lot of reading material, but I think the last one provides the most information.

I hope this is useful to you.

Best Regards,
US Iceman

Josip
07-04-2006, 12:36 AM
Thanks US Iceman,

for links and attachments :)

I have to review all to get as much as possible information about.

In this moment I am in Saudi Arabia, traveling up and down occupied with lot of refrigeration inspection for one mixed Italian -Saudi company. We have to prepare very urgently one offer for one cold store. This is very specific request due to kind of goods to store. Later on if we succeed I will come back with some info about.

I was absent for some time because it is not very easy to come to internet here except for emails. Working all day in the evening I'm tired and still have to finish some reports and so on..:)

Also they have only a few DSL connections and almost allways I have to use modem with very high speed, sometimes with only 21 kbps,fast ha,:) ). You must agree with me that is not so attractive to come to RE and read posts. When I come back home I will find a time to review some articles :)

Here they have a lot of old refrigeration plants (*****s, and ammonia) to revamp but also a lot of new projects.

US Iceman
07-04-2006, 01:01 AM
...with very high speed, sometimes with only 21 kbps,fast ha :)

Morse code was faster than this. :p

I wondered where you were. Have a safe and prosperous trip.

Good luck with the projects!! Let me know how everything works out.

Peter_1
08-04-2006, 05:53 PM
We service a NH3 plant with glycol at -10C.
Glycol is used to cool cold stores and meat cutting rooms.
What's different compared to onion cold rooms?

We've also done over the years some potatoe cold storages (+/- 5 pieces and biggest was +/- 30 x 15 x 6 m)

What do you need for info because you know better the basics then I.

Josip
08-04-2006, 09:24 PM
Hello Peter_1

This will be the same system, primary circuit with ammonia and secondary with glycol for cooling, heating and defrosting.

There will be 4 circuits: cold and hot ammonia and cold and warm glycol

It sounds very simple but when you put all on paper...you are coming to about 2 MW of refrigeration

Due to a long time of onion and potato preservation there are some specific requests like:

- using outside air only if colder than the product temperature, this air could be used for cooling down the product with temperature control for automatic hatches (to save energy a lot of cooling will be only by ventilation, both for onion and potato)

- controlled room atmosphere

- humidity control

- to define complete equipment we have to know as much as possible about complete cooling procedure, then before delivery of goods to market reheating (for example potato to control sugar content) again, an so on...

-SCADA system

- for example potato must be kept above 0C (+4/5) depending on final use and on type of potato, in another hand onion must go down to 0C and for this there must be forced cooling

- we have to keep in mind, those kind of goods are still alive and with wrong procedure it is very easy to loose a lot of goods due to decaying

- let's say it is not a big problem to design cold store for ice cream, but to find out the latest (or just new) news in this field and to design refrigeration equipment I must know what about I have to take care

-links provided by US Iceman were of big help for better understanding how to do that design regarding food preservation process

US Iceman
08-04-2006, 10:57 PM
Josip,

I would expect the control of the humidity during the cold weather might be the most difficult. For example, when the hatches or louvers are being opened to the storage space in cold weather.

The low RH of the cold outside air will require humidity injection to reduce product drying. Would you use steam or ultrasonic humidifiers?

Will you use ceiling hung evaporators or large central station air handlers (like large HVAC systems)?

This sounds like a very interesting project.

Peter_1
09-04-2006, 01:00 AM
Josip,
Could guess immiediately your question was much more difficult.
Will re-read it tomorrow - it's 02:00 night and coming back from a late dinner with a friend - and look on what points I perhaps can help you.
Which will be very little I think compared to the experience you have.

Peter

Andy
09-04-2006, 09:46 AM
Hi:)

most stores of this nature over here would be smaller, using moist air coolers, An air cooler evaporator with a sump under it, with water being pumped over it and chilled, with the air leaving the top of the evaporator thru packing to keep water spray down.

The ventilation cooling is not normally used due to the low winter humidity, and I suppose the relativly small refrigeration loads anyway.

Kind Regards. Andy:)

US Iceman
09-04-2006, 06:01 PM
Andy,

Do you have any pictures or links you can post for this?


...An air cooler evaporator with a sump under it, with water being pumped over it and chilled, with the air leaving the top of the evaporator thru packing to keep water spray down.

This seems similar to what we would call an air washer, but has the evaporator coil inside.

Does the evaporator coil have only prime surface tubing or does it also fan secondary surface (fins)?

Thanks

Andy
09-04-2006, 07:11 PM
Andy,

Do you have any pictures or links you can post for this?



This seems similar to what we would call an air washer, but has the evaporator coil inside.

Does the evaporator coil have only prime surface tubing or does it also fan secondary surface (fins)?

Thanks

Sorry Iceman I can't find any links, but I will look up some manufacturers when in work Monday.

The evaporators are usually custom built and include fins on the coils, as they may be used for cooling without moist air, for short term storage or packaged goods.

Baltimore aircoil make a wet air cooler, it is simply water of an ice bank built up at night, pumped around and sprayed over a cooler that looks much like a cooling tower converted (uglyiest thing you ever seen)

kind Regards Andy:)

US Iceman
09-04-2006, 08:42 PM
Thanks Andy. I would appreciate reviewing any material you can post or direct me to.

What you describe sounds exactly like a hydro-cooling system.

Peter_1
10-04-2006, 09:34 AM
Is it something like this?
http://www.fujikoki.co.jp/en/product/ot/pr_ot_mat.html

or this
http://www.ecokool.com/adiabatic_expansion_cooling_of_gases.htm

US Iceman
10-04-2006, 02:36 PM
Peter,

The links you posted are similar to one part of the process Andy is describing. The evaporative coolers (sometimes called swamp coolers here in the US) simply cool the air by evaporating water. Since the ambient wet bulb temperature determines the evaporative process, the air temperature cannot be cooled any lower.

On the hydro-cooler approach it is similar except the water is cooled either by ice (using an ice bank as Andy described) or by refrigerating the water to the desired temperature.

I will look for some links and pictures to post.

US Iceman
10-04-2006, 04:05 PM
Here are some links for the evaporative coolers:

Residential
http://phoenix.gov/WATER/evapcool.html

hydrocooling
http://www.bae.ncsu.edu/programs/extension/publicat/postharv/ag-414-4/index.html

http://www.baltaircoil.com/english/info_center/pubs/evap_PRD48.pdf

http://b.staff.umkc.edu/beckerb/publications/journals/hydrocooling.pdf

For some reason I cannot find the large air washers that are used in textile mills. These systems were also used to in large air conditioning systems.

US Iceman
10-04-2006, 04:55 PM
OK guys, I finally found what I was looking for.

http://www.luwaamericas.com/mvaw.pdf

http://www.luwaamericas.com/cpahu.pdf

This may be one other way to solve the onion and potato storage issue Josip asked about.

The water in circulation through the air washer can be cooled by using an ammonia chiller. The cold water cools the air stream into the storage rooms.

The air could be ducted into the spaces and distributed by any methods. If the ventilation system is arranged for a closed circuit (recirculating the air) the outside air dampers could be used for make-up air and oxygen content when necessary. (To get the controlled atmosphere requirements, if necessary)

Since these are factory fabricated units any fan could be specified with any static pressure requirement for the air distribution system.

(As long as the walls on the packaged unit do not blow out :D )

The graphic below and the links are from Luwa Americas, which used to be the Bahnson air washers.

Andy
10-04-2006, 07:45 PM
Here are some links for the evaporative coolers:

Residential
http://phoenix.gov/WATER/evapcool.html

hydrocooling
http://www.bae.ncsu.edu/programs/extension/publicat/postharv/ag-414-4/index.html

http://www.baltaircoil.com/english/info_center/pubs/evap_PRD48.pdf

http://b.staff.umkc.edu/beckerb/publications/journals/hydrocooling.pdf

For some reason I cannot find the large air washers that are used in textile mills. These systems were also used to in large air conditioning systems.

Iceman the hydro cooling is one way of acheiving the desired room humidity. But the system I was thinking of is different.

A conventional dry air cooler is incorporated into the hydro cooler. The refrigeration is DX not water cooled the DX cooler is suspended above a water sump, with air being drawn thru it and water sprayed over it, just the same as an evaporative condenser, except the refrigerant is cooling the water and air passing over it not heating it. The system is an evaporative cooler and a DX cooler combined.

Kind Regards. Andy:)

US Iceman
10-04-2006, 08:33 PM
...just the same as an evaporative condenser, except the refrigerant is cooling the water and air passing over it not heating it.

OK, I understand now. Instead of using an evaporative condenser to reject heat, you use it for cooling.

Why DX on the coils? Do you use this so that the refrigerant charge is not too large, as with a flooded coil?

How were the cooling capacities developed or calculated for this type of application? This is interesting...

Thanks Andy. I continue to learn something new every day!:)

Andy
10-04-2006, 09:07 PM
OK, I understand now. Instead of using an evaporative condenser to reject heat, you use it for cooling.

Why DX on the coils? Do you use this so that the refrigerant charge is not too large, as with a flooded coil?

How were the cooling capacities developed or calculated for this type of application? This is interesting...

Thanks Andy. I continue to learn something new every day!:)

DX because of the small size, probably in the region of 70kW. The ones we have are mostly on dx R22.
No reason why Josip couldn't use an evaporative condenser with a pump circ coil as an evaporator, how you would ever get the duties of Baltimore I don't know:D
But I would love to hear the pause on the phone after asking:D
Capacities are exactly as per the DX capacity except the latent load comes from the water placed in the air by the moist air cooler, not from the air or the product directly.

Kind Regards Andy:)

US Iceman
10-04-2006, 09:15 PM
But I would love to hear the pause on the phone after asking :D .

Absolutely priceless...:eek:

I was thinking the same thing.

jhorn
26-04-2006, 11:22 PM
I just ran into this post and thought I would let you know that there is a delicate balance between humidity and temperature for the long term storage of onions. You may want to invest in a preconfigured controller for this project instead of starting from zero.

http://www.jmcvr.com/panels.htm

just a thought.

Josip
27-04-2006, 12:33 AM
I just ran into this post and thought I would let you know that there is a delicate balance between humidity and temperature for the long term storage of onions. You may want to invest in a preconfigured controller for this project instead of starting from zero.

http://www.jmcvr.com/panels.htm

just a thought.

Thanks jhorn,

site visited, looks interesting, we have to speak with our client about and then contact JMC company.

Best regards,

Josip

Gaafar
03-09-2009, 08:57 PM
Hello,

please help me to find some more info regarding this article. Primary circuit will be with ammonia and secondary with glycol.

Any help is welcome,

Thanks,

Josip
if you are in Saudi Arabia you can contact me , our company have good experience in such jobs (Gaafar Hamad:marcokhobar@eajb.com.sa)
however following company site can help:HORTAGRO

jwasir
09-09-2009, 05:40 PM
Andy,

What is the water temp v/s air/room temp?

nsien
13-09-2010, 11:39 AM
Hello,

I waould like to join continuously this toppic.

I am designing an air cooler what will use for the Onion processing roomssuch as cutting room... i heard that the onions can create sulfuric acid, is it right?
Can every one help to advise the suitable material for this case ( i am meaning about the fins and tubes)?

Thanks very much.
VS.