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Phillip2009
03-10-2013, 01:22 PM
I've put my foot in a bear trap by purchasing a used freezer room. Problem is that they obviously grabbed random parts to slap my system together. My compressor runs most of the time, switching off just before defrost mode....drops temp...then battles to get to the required -20 deg C. Minus 25 would have been great. I now need to find out which units I can use, and which needs replacing. I need to know so that I can at least request the proper parts. Bear with me if the terminology is incorrect but details are:
Room size: 2m x 1.6 x 2.1 high, Standard Polystyrene 150mm panels, concrete floor over insulation panels, Compressor MANEUROP NTZ 096A4LR1A, Refrigerant R507, Condenser 5-1-916, inside double fan blower unit SU 101 H, Expansion valve Danfoss TES 2 068Z3403, No.2 orifice.

I'd be grateful to someone who could recommend something useful other than dumping everything!

Rob White
03-10-2013, 01:39 PM
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I would ask

Was the room working before you bought it?

If it was then why is it not working now?

Running 24/7 (except defrost) does indicate
a problem, but you have not established if
it is the equipment or the way the equipment
has been fitted together.

By the way no product I know of needs to be
stored at minus 25 degC. Minus 18 degC is OK
for all products except ice cream.

What are you going to put in the thing?

Regards

Rob

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Phillip2009
03-10-2013, 05:23 PM
Pomegranate juice....It takes more to keep it frozen than other juices or milk...it seems. The freezer does work and does get to -20 eventually, but will first bankrupt me before packing up as it gets pretty hot. I've had a reply from a professional who came to advise me, this afternoon. He reckons the blower inside is the problem. It's meant for a cold room not freezer and also says the orifice is too small. He's going to get prices on a bigger blower that compliments the compressor.....does this make sense?

nike123
03-10-2013, 06:02 PM
Are you talking here about keeping goods frozen or freezing the goods, since there is VERY BIG (IN RANGE OF 4-5 TIMES) difference in between.

Phillip2009
03-10-2013, 08:54 PM
Fruit gets kept in cold room at 5 degrees C. Removed at intervals and juiced, so temp would rise to probably 10 Degrees, bottled and added to already accumulated stock. Added amounts are small (+/- 20L of bottled product). Stocks then to be stored for a long time. Not sure of total capacity as haven't had a chance to get anywhere with this unit. I need help from someone who knows the specs to match a blower with the compressor, which is a overkill but acceptable, I'm told.

Rob White
04-10-2013, 08:56 AM
Pomegranate juice....It takes more to keep it frozen than other juices or milk...it seems. The freezer does work and does get to -20 eventually, but will first bankrupt me before packing up as it gets pretty hot. I've had a reply from a professional who came to advise me, this afternoon. He reckons the blower inside is the problem. It's meant for a cold room not freezer and also says the orifice is too small. He's going to get prices on a bigger blower that compliments the compressor.....does this make sense?

The evaporator and orifice being too small is possible.

But you seem to be confusing temperature and heat load.

All products have a specific heat load and it is that heat load,
that you will be moving from the fruit then temperature comes
in.

Food Specific Heat above Freezing Specific Heat below Freezing
(Btu/lboF) (KJ/kgoC) (Kcal/kgoC) (Btu/lboF) (KJ/kgoC) (Kcal/kgoC)
Apples 0.87 3.64 0.87 0.42 1.76 0.42
Pineapple, sliced or crushed 0.82 3.43 0.82 0.41 1.72 0.41
Pineapple, juice 0.9 3.77 0.9 0.43 1.8 0.43
Plums 0.89 3.73 0.89 0.43 1.8 0.43
Pomegranate 0.85 3.56 0.85 0.41 1.72 0.41
Pompano 0.77 3.22 0.77 0.39 1.63 0.39
Porgy 0.81 3.39 0.81 0.4 1.67 0.4

Because you have to move the heat from the fruit, from both above and
below freezing you have to calculate the size of the system accordingly.

Or you could just buy a second hand freezer box and hope it all works.

Oh hold on a min, you already have :p

Just bear in mind if you up the size of the evaporator you up the workload
and therefore you put more work on the compressor. If the compressor
"gets pretty hot" as you say then it will be even hotter after the modification.

Rob

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Phillip2009
04-10-2013, 11:06 AM
Thanks Rob.... only thought from my side is that if you enlarge the inside blower (or evaporator), it has more pipes for cold transfer and a bigger orifice for the gas to move through faster. Will this efficiency not shorten the compressor's running time and therefore prevent it heating up?

Rob White
04-10-2013, 01:16 PM
.

You are not "transferring cold"......

You are transferring heat.

Heat from your product (pomegranates) moves to the refrigerant
in the evaporator (blower) and is transferred outside in the refrigerant.

Any heat that goes into the system on the inside of the coldroom must
be rejected by the outside unit. If you increase the size of the evap then
there will be more heat added to the system and that will cause more work
for your condensing unit to deal with.

Its a very fine balance, but what goes in, must come out. If it does not the
system will fall over.

Regards

Rob

.

Phillip2009
04-10-2013, 07:39 PM
Thanks Rob...now that explanation emphasizes the importance of the condensing unit being outside in the wind and not inside the building on top of the freezer unit (as they placed it) where the ambient temp is between 25-40degrees C. The problem is that the system is struggling even when it's empty, i.e no hot product added and this with the outside temp moderate. Anyway, don't want to waste your time....hope the professional comes up with something that works. Quite a helpless feeling, being in someone else's hands.

Rob White
05-10-2013, 10:07 AM
Thanks Rob...now that explanation emphasizes the importance of the condensing unit being outside in the wind and not inside the building on top of the freezer unit (as they placed it) where the ambient temp is between 25-40degrees C. The problem is that the system is struggling even when it's empty, i.e no hot product added and this with the outside temp moderate. Anyway, don't want to waste your time....hope the professional comes up with something that works. Quite a helpless feeling, being in someone else's hands.

Your not wasting my time :)

But you are doing the right thing by letting someone look at it.

Regards

Rob

.

Gary
05-10-2013, 03:04 PM
Evap air in temp _____.
Evap air out temp _____.
Low side pressure converted to saturation temp _____.
Suction line temp near compressor inlet _____.

Cond air in temp _____.
Cond air out temp _____.
High side pressure converted to saturation temp _____.
Liquid line temp (outside box) _____.