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iceway
11-04-2007, 07:51 PM
hi firends
i need your helps about a freezing tunnel
in this case our dimensions is 8m*4m*3m
l = 8 m
w=4 m
h=3 m
if i want to explain more i should say in this case we shoulde freeze 6 tone chize in every day and in 8 hours
parameters: ambiant tempreture : 40 c
freezing temputure : -30 c
the peroid of intering each chitz(time) is 180 kg in 30min
in first mounths and the begin of produce we have 3 tone of chitz for a day
in this case we use meat in a chitz or hotdogs.
my most needed parametrs is capacity of compressore (hp) and evapratore cooling capacity (kw) and condensing capacity(kw)?
if you can please tell me the way of callculating.
i am wait plz.

lana
11-04-2007, 08:25 PM
my most needed parametrs is capacity of compressore (hp) and evapratore cooling capacity (kw) and condensing capacity(kw)?


Hi iceway,

What you need is what consultants are paid to calculate:rolleyes: .
If you get your answer here come and see me for designing the evaporator:) .

Good Luck
LANA

Peter_1
11-04-2007, 08:29 PM
What's the entering temperature of the products?
Rough estimate for an entering of 2C, 6 ton over 8 hours to be frozen to -20C.
Let's take (2* 6000/8 * 1.16) + (6000/8*85) + (20*6000/8 * 1.16) = +/- 83 kW* 1,2 (for fans, defrost, air infiltration) gives +/- 100 kW.
This will need +/- 100 HP compressor power, evaporating at -30C and condensing at +/-40C

If you will have to condens at 50C (ambient 40C) then you must select a compressor at this higher condensing pressures.

If every30 minutes a load enters, then you will have to make sure that you work according the FIFO principle.

Try to use hot gas defrost and install an additional evaporator for the defrost.
BTW , what's chize?

This were some quick thoughts

lana
11-04-2007, 08:41 PM
What's the entering temperature of the products?
Rough estimate for an entering of 2C, 6 ton over 8 hours to be frozen to -20C.
Let's take (2* 6000/8 * 1.16) + (6000/8*85) + (20*6000/8 * 1.16) = +/- 83 kW* 1,2 (for fans, defrost, air infiltration) gives +/- 100 kW.


Hi Peter,

My first estimate was 85 kW (in 8 hours). BUT for -30C room temperature he has to use double stage compressors. The biggest available is 30HP Bitzer which gives 21kW (at -40C evaporating). So you see he needs almost 5 compressors:eek: :eek: :eek: .
For 5 compressors he has to use an evaporator which will be so huge that it will not fit in the room.

I hear this stories ten times in a week :eek: :eek: .
Sorry.

The only solution is to reduce the load.

Good Luck.

nh3wizard
11-04-2007, 09:06 PM
I think he means cheese

Peter_1
11-04-2007, 09:21 PM
He could also go for some screws.

2 Bitzers two stage S66F60.2Y can do the job when evaporating at -40C.

When the room can be held at -23C, evaporating at -30C, then 2 TandemOctagons of Bitzer can gives this capacity. (= +/- half the price of the first proposal at -40C)

I think the room is large enough, I just checked very quick Goedhart and Heatcraft and it is possible.

Iceway, you must warn/inform your client that there's a huge difference in a room of -20C and one at -30C and even -35C.
These differences are not high but very high.

What will you do with the narrow width of 4 m? At least that's my opinion.

Iceway, don't forget that blast freezers are one of the most difficult cooling jobs you can find. So be very careful when accepting this job.

lana
11-04-2007, 09:44 PM
Dear Peter,

Thats exactly my point. If this thread was for another country I would not reply in that way.
Because I know the situation here :confused: .
If you suggest a screw the client will absolutely die :D . If you suggest Tandem you will get : What did you say , sorry what was that :confused: . (Of course not all the clients :D ).

The dimensions mentioned is a typical freezing tunnel dimension here :eek: .
I dealt with these so called projects many times. Sometimes the evaporator doesn't go through the door :confused: . If I want to lower the height of the evaporator then, I can not get the capacity :D .
Sometimes I don't know I have to cry or I have to laugh.
At the end I would like to say that this is not iceway's fault at all and my comments are not to criticize him. The cold store owner is the problem. Because 99% of them have no idea what they are saying and demanding. I the designer says for this and that reason it is not possible then he is out of the game. Some other guy comes into the game who has no idea what he is doing. Only says : yes sir it is possible, I will do it for you. He gets the money, cold store doesn't work and Bye Bye.

Cheers

Peter_1
11-04-2007, 09:58 PM
I noticed just now that both of you are from Iran.
I understand your point of view and you're right.

Iceway, this doesn't change my last recommendation: blast freezers are very difficult to design and to build.

Peter_1
11-04-2007, 09:59 PM
Better pay some moeny for the consult and the calculation. I think - at least that's how it works in Belgium - if anything is wrong calculated, then it's their fault. They're responsible for the total concept.

lana
11-04-2007, 10:10 PM
Better pay some moeny for the consult and the calculation. I think - at least that's how it works in Belgium - if anything is wrong calculated, then it's their fault. They're responsible for the total concept.


Yes Sir. BUT BUT BUT.
Maybe you don't believe me but I add the consultation fees on my products if I design everything for them.
No body pays for consultation in cold stores specially "*****" ones.
This year I had a client who wanted to build cold stores for Kiwi. He did some research in his area and saw how the cold stores are working and always breaking the compressor and ... then he convinced that paying the consultation fee is more reasonable.
So he paid and we designed without any problem. Everybody happy.
Anyway it is depressing and also this thread is drifting away.
Good luck.
Cheers

Gonzalo Arias
14-04-2007, 04:29 AM
Dear friend:
Please tell me more about the product:
It is meat?
It is in boxes?
What size?
Does the door opens every 30min?
How is the product organized into de tunnel?
Can you use NH3?
Also try to find a book called "refrigeration principles by Dossat?
Best regards?
Gonzalo

Peter_1
14-04-2007, 07:55 AM
Iceway, are you still alive?:o

Magoo
29-06-2007, 11:21 PM
Cheese freezing tunnels vary from cheese to cheeses and packaging variations, blister packed in corrigated cartons or open stacked on trolleys, manually loaded as produced, or loaded in on pallets.
I have found that getting a sample of the finished product and carrying out actual trials works better that reading a thousand books. Get a freezer small chest type at a known temperature, put temps sensors in product (in the middle ) place in freezer and record everything possible. This will give a reasonable profile of cooling rate, then repeat with a fan blasting over product at given flow rate, say 3m^/sec. and compare results, add safety margin and then you have some accurate knowledge on your particular cheese.

hope this helps regards Magoo:)

Samarjit Sen
30-06-2007, 09:23 AM
Lana, what you have said is exactly what we have in our country. We go a little bit ahead. The clients visit a number of similar plants and on the basis of these he tries to have the same installed himself. There are some refrigeration contractors who accept such jobs, and when finally the entire system has gone haywire, the client blames the contractor. Then the contractor approached some consultants, but by that time it is too late and the client does not want to ay the legitimate fees to the consultant.

Only yesterday one so called consultant had contacted me and wanted to know how to construct and design a freezer tunnel. I told him that it costs money to give the details and he will not understand whatever I tell him. He took some of my projects photographs, which I told him has no value as with it he cannot design a system.

The state of affairs is very bad here as no one wants to understand that refrigeration is not that easy.

lana
30-06-2007, 01:19 PM
Hi Samarjit Sen,

I always say this to my clients :
If you want to build a building what would you do? Would you go to the office of an architect and pay for the design or would you employ a building contractor to build the building for you without any design?

All of them say that they would pay the architect to design the building. Then I say that the cold store is the same, you have to pay for the design.
The answer is : "come on there are four components to install, what design. You want to charge us for nothing.":eek:

This is really sad. They loose millions but don't want to pay a little for consultation.


Cheers

Samarjit Sen
30-06-2007, 02:25 PM
Hi Lana,

One thing I have seen. It is that these clients pay for the consultancy that too a heavy amount to those consultants who have no knowledge of refrigeration but are street smart characters. Then these so called consultants try to find ways out to get the system design from the contractors assuring them they shall be awarded the contract.

The outcome is that the project gets spoilt and by the time the client comes to us he is as good as a dead duck as he has not only spent a considerable amount, but has equipments in hand which are worthless and at times are from a ship cutting yard which is very well known in our country for the refigeration equipments.