Maneurop MT51HK4A - Freezer Room

Hi,

I have a low temp -18 freezer room approx 2m x 4m with a 3 fan evaporator. Compressor is a Maneurop MT51HK4A that appears to be a replacement from original (given the burnout drier still in place). Freezer running on 404A and this would have been also converted over given the cond set would be 10 year old.

I have recently replaced TX with 404 Danfoss and removed suction burn out and replaced liquid drier. Cleaned cond coils. Refrigerant levels OK with clear sight but has long 20m run. With SH at factory, I am getting approx -7C air off the evap coil with frosting on suction line about 5m from compressor. Room temp more like cool room. Suction arount 100kpa and discharge around the 1500kpa mark (ambient around 30C). Opened valve a one turn and suction now at 250kpa with frosting to compressor and room now slowly getting down.

Worried about refrig flood back. Wondering if this Maneurop MT51HK4A suited to low temp freezer room and whether it incorrect replacement from original. What pressures should I be getting for a 404 freezer room? Being mainly (99%) in the Air Con field I am struggling with this one.

Hope someone can shed some light on this one.

Regards

That is not low temp compressor, its operating envelope ends at -25°C evaporation temperature.

I will get those details when I return to site 2morrow.

Regards

Quote:

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Originally Posted by Hatchy

I will get those details when I return to site 2morrow.

Regards

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No need! Your compressor is not for low temperature application.

http://farm4.static.flickr.com/3134/...8190ab_o_d.png

Hi Hatchy
Nike123 is correct, the compressor fitted is a medium temp compressor the MT gives the duty. You will need to change with a LTZ series compressor. Get the details of the evap, load on room and calculate the size of the compressor needed. As you are in Aust Actrol will do it all for you and can supply the compressor.
When you install mak sure you have frost back to the compressor and the compressor is cool to touch. Maneurop compressors have an internal overload and if the trips because the compressor is running hot it can take 3 hours or longer to reset. Maneurops can run with frost on the compressor with no problems.
Paul

hey hatchy,

Couple of Questions

• What was the original complaint?
• Why was the tx-valve changed?
• Is there any form of compressor protection ie CPR valve or MOP element on tx valve?

I suspect the compressor is possibly the cause of your problem condsidering its not in its correct applications. Saying that it must have worked for some time the way it is?

Cheers

Hey Guys,

Thanks for advise so for. Still have not got up there to get evap/tx details but going from responses, compressor is the issue.

>What was the original complaint?<

During hot afternoons the freezer would struggle causing alarm activation. Fitted temp logger and discovered that after 6pm defrost cycle the freezer struggled to return below -7C within the 40min alarm delay causing callout. Checked refrigerant levels/sight glass and all appeared ok but pressures all over the place.

>Why was the tx-valve changed?<

I saw that it was a R502 valve and because I could not stabilize pressures I replaced valve in desperation thinking this may have been cause.

>Is there any form of compressor protection ie CPR valve or MOP element on tx valve?<

There is a CPR valve fitted on compressor.

I did suspect the compressor the problem and thank you for validating this. Freezer is currently working ok (going over temp logs) but I changed defrost cycle to 9pm from 6pm to get away from hot afternoon temps. Conditions have been mild last week also.

Once again, thanks

Hatch

You could check evaporator fins spacing. If it is 6 mm or lower, then original design is for medium temperature or high temperature application and someone wants that plant works something it was not designed for.

Also, that compressor will not live long if it continue to work at that evaporation temperatures.

Hey Hatchy,
Is it maneurop condensing unit? The condenser on these unit will only be 32C ambient. With hot summer days above 35C these things always struggle more so with the wrong compressor. The units trip out on h.p, our cycles on h.p if it auto reset. and recovery time is poor becaause the system is running on such a high head pressure.

I would reccommend that you put on a new condensing unit with a 46C ambient condenser. The l'unite hermetique units are pretty good. Just put a new one in today on a freezer room. It will be the best thing for the client in the long term. :)

Quote:

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Originally Posted by fridgey

Hey Hatchy,
Is it maneurop condensing unit? The condenser on these unit will only be 32C ambient. With hot summer days above 35C these things always struggle more so with the wrong compressor. The units trip out on h.p, our cycles on h.p if it auto reset. and recovery time is poor becaause the system is running on such a high head pressure.

I would reccommend that you put on a new condensing unit with a 46C ambient condenser. The l'unite hermetique units are pretty good. Just put a new one in today on a freezer room. It will be the best thing for the client in the long term. :)

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Isn't that approach from tale toward head?:eek:
He first need to find out what is room required capacity and evaporator TD,
then he need to find is this present evaporator of right size and kind for that application,
then he need to select correct compressor for that evaporator
and least, he need to size condenser according to used compressor, his refrigeration capacity at design conditions and outdoor conditions.
How are you going to do that from condenser as starting point?

Thanks guys,

Will keep you posted on outcome. With 36C+ temps expected 2morrow it will sure test the freezer room.

The freezer is used for livestock lab to keep samples. Lab techs in and out throughout the day. Any idea what heat load to expect on a (approx) 2m x 3m freezer used for this application?

I will traveling back up there 2morrow to do other site work, check freezer operation and gather further info as well as discuss incorrect compressor install couple years back with site manager.

You know! I should have realized that "MT" stood for the compressor duty in first instance. Makes sense now. Doh!

Guess the cheapest quote not always the best job.

Quote:

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Originally Posted by Hatchy

Thanks guys,

Will keep you posted on outcome. With 36C+ temps expected 2morrow it will sure test the freezer room.

The freezer is used for livestock lab to keep samples. Lab techs in and out throughout the day. Any idea what heat load to expect on a (approx) 2m x 3m freezer used for this application?

I will traveling back up there 2morrow to do other site work, check freezer operation and gather further info as well as discuss incorrect compressor install couple years back with site manager.

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What is isolation size and type?
What are outdoor maximum temperatures where cold room is located?
Does the floor insulated?
What is height?
What is power of fans and lights?
What is frequency of door opening (hrs open per day) or (min open per hour) and what is daily amount and entering temperature of samples? Make estimate.
What is door dimension?
Are there strip curtains mounted?
What is average temperature of air infiltrating thru doors

Right! back with more details.

Turns out that compressor is the correct one for this condenser. Maneurop GM50-4CT which is a medium temp extended unit that will do about 3200W @ -25Deg.C SST & 32 Deg.C ambient.

It hooked to a Coldwright LLM E 135 Evap that is 4200W.

No wonder it struggling with current conditions!

More info to consider:

1. Room measured @ 3m(L) x 1.4m(W) x 2.3m(H)

2. Insulation is 150mm (Not sure bout floor - concrete). sandwich poly.

3. 40 metre pipe run (all one level with one 3m vertical rise up wall to ceiling space). Bad guess from my original 20 metre estimate but I measured 2day at 40 metres.

4. 28.5mm Suction and 12.7mm Liquid between the two.

5. Danfoss TES2 R404A/R507 (can't remember orifice size but sized on condenser details)

>What are outdoor maximum temperatures where cold room is located?>

Max temps of 35Deg.C approx. Cond unit also located with 2 x A/C Cond units, 2 x coolroom cond units and one other low temp cond unit within a colourbond paneled off area.

>What is power of fans and lights?>

Single flouro (not sure watts). 3 x fans with 250mm 5 blades (again not sure on watts)

>What is frequency of door opening<

Length of piece of string? I would guess that they would open once every hour for maybe 2 min max as it is ordered ok. Entering temps would be 22Deg.C given the space is aircon.

>What is door dimension?<

Guessing 2m(H) x 1m(W)

>Are there strip curtains mounted?<

No

>What is average temperature of air infiltrating thru doors<

22Deg.C

I have been quoted a LTZ40-11.8/42 R404A Low Temp unit (Guess it a Maneurop) that has 3.3HP Comp. At 43Deg.C ambient: 1748w @ -35 SST > 4133w @ -20 SST.

My concern is if this quoted unit sufficient and 40 metre pipe run.

Regards

Check this calculation!
Attachment 2645

Quote:

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Originally Posted by Hatchy

Right! back with more details.

Turns out that compressor is the correct one for this condenser. Maneurop GM50-4CT which is a medium temp extended unit that will do about 3200W @ -25Deg.C SST & 32 Deg.C ambient.

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You said in your first post that compressor is:

Quote:

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Compressor is a Maneurop MT51HK4A

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Quote:

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Originally Posted by Hatchy

There is a CPR valve fitted on compressor.

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I'm betting the CPR is set too low.

The coil is oversized for the condensing unit. Without the CPR, this could overload the compressor under heavy load. If the CPR is set too high, the compressor will overload. If the CPR is set too low, the pulldown will be too slow.

Just when I was starting to understand bar, people start throwing kpa at me.

Psi, anyone? :confused:

Quote:

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Originally Posted by Gary

Just when I was starting to understand bar, people start throwing kpa at me.

Psi, anyone? :confused:

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1 Bar 100kPa
1 Bar 0,1MPa
:D

Thanks, Nike

Quote:

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Originally Posted by Hatchy

Suction arount 100kpa and discharge around the 1500kpa mark (ambient around 30C).

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If I'm converting correctly, this gives us a saturated condensing temp of about 36C, which means we have a cond TD of about 6K, which means very little heat load being picked up in the evap.

I'm wondering if those suction pressures were taken upstream or downstream from the CPR?

Nike123,
I think you misunderstood what I was trying to say.

Quote:

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Isn't that approach from tale toward head?:eek:
He first need to find out what is room required capacity and evaporator TD,
then he need to find is this present evaporator of right size and kind for that application,
then he need to select correct compressor for that evaporator
and least, he need to size condenser according to used compressor, his refrigeration capacity at design conditions and outdoor conditions.
How are you going to do that from condenser as starting point?

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I wasn't at all suggesting that he should just put in any old condensing unit. Of course it has to be sized to the room, evaporator, condition etc.

What I was alluding to was here in most parts of australia we have days that regularley exceed 40C ambient. In the past condensing unit capacity were based on a 32C ambient. The thinking being there is only a couple of day of the year exceeding this temp.
These days we seem to be getting more extreme temperature with some days even hitting 45C. Subsequently what I was suggesting was that if you are going to size a condensing unit make sure its on either a 43C or 46C ambient to cope with worst possible conditions.

Of course this can cause problems with over condensing in winter, thats were fan speed control on fan motor comes in. :D

Cheers

Quote:

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Originally Posted by fridgey

Nike123,
I think you misunderstood what I was trying to say.

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Could be, easily.

Gary, I think your on the money. Looking at the numbers 6k TD across the condenser in low.

Quote:

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With SH at factory, I am getting approx -7C air off the evap coil

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Considering the saturated vapour temperature of the refrigerant is -30C, This suggest that there is high superheat.


Is the orifice right?

Quote:

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Danfoss TES2 R404A/R507 (can't remember orifice size but sized on condenser details)

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Hatchy, You should have a No. 3 Orifice which does up to 4.2KW on R404a which should match your evap well.

Cheers

Quote:

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Originally Posted by fridgey

Considering the saturated vapour temperature of the refrigerant is -30C, This suggest that there is high superheat.

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This assumes the pressure reading is from the upstream side of the CPR. It ain't necessarily so.

Quote:

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Originally Posted by nike123

You said in your first post that compressor is:

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Sure did, Maneurop MT51HK4A compressor fitted to a Maneurop GM50-4CT Condenser unit. A GM50-4CT is classed as medium temp extended. Not sure why it fitted in first place.

I tried to use the "M-Quote" feature but had trouble working it out.

>I'm betting the CPR is set too low.<

Fully opened. SH too high but when TX opened 1/2 turn it flooded back with frost surrounding suction inlet to compressor. Thought this too be excessive.

>Is the orifice right?<

No3 fitted brand new with new valve.

I am going to upgrade condenser and have been quoted: LTZ40-11.8/42 R404A Low Temp unit.

Too much of a mismatch between current condenser and evap when ambient temps exceed the 32 Deg.C mark. Given the valuable contents I can't stuff around with this any more.

My concern now is will the LTZ40-11.8/42 R404A Low Temp unit quoted be OK. Thoughts?

Seems to be operating OK going over data log but it did trip HP after midday defrost when ambient about 34 Deg.C

Regards

Quote:

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Originally Posted by Hatchy

Sure did, Maneurop MT51HK4A compressor fitted to a Maneurop GM50-4CT Condenser unit. A GM50-4CT is classed as medium temp extended. Not sure why it fitted in first place.

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Medium temperature extended doesn't mean that it is suitable for operation with -25°C evaporation. It is still at the end of compressor operating envelope Except some additional mean of cooling of compressor is done at condensing unit assembly.
Do you have documentation of that condensing unit. I cannot find anything at Maneurop site or in RS+ software? Only what Google return is some obsolete Russian pages with no technical data.

Have to post at least 15 before I can add URL. Number 14

Have to post at least 15 before I can add URL. Number 15

http://www.airzone.com.au/files/uplo...202%20PT_1.pdf

Page 4, second last. Item code CU2053AL.

Will add Oil Separator and Suction Accum as well.

Quote:

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Originally Posted by Hatchy

http://www.airzone.com.au/files/uplo...202%20PT_1.pdf

Page 4, second last. Item code CU2053AL.

Will add Oil Separator and Suction Accum as well.

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I suppose this condensing unit is what you are going to install and that is OK (if evaporator matches).
I asked data about already installed condensing unit, the one that you are tried to fix and same one what has Maneurop MT51HK4A compressor to see what is his operating envelope in "extended medium temperature" and how is that achieved when compressor is not constructed to do that.
Are we having problem in understanding of each other here?

I have no data on the original condenser. Local Refrig wholesaler manager immediately informed me that it was a medium extended condenser and the Maneurop MT51HK4A was the right one for this unit. How he knew this "off the top of his head" I don't know but I will quiz him next time.

I tried to google it also and got no data.

When you changed the tx valve,did you check the tonage of the previous tx valve?

Hatchy,

before 2 week i installed mtz56 for freezer rooms with cooling load 5kW at -25 evap with R22 this was for Russian ship. My client wonts to use R22 becouse has large quantity in stock. Evaporator was without fans evap. battery. Maybe Yuo know this type wants very high SH 20K. I was put liq. inj. system to controlling compressor overheating and set them on 125C.
So when temp. in room was -18 degree Suction was about 0.6bar/-33C saturated.
It is incredible for me that You with normal evap - with fans that is greater than compressor power ( you say 4200wats) and with r404 has only -7C. I check compressor it gives at te=-25 3.0kw this is completely enough for your room.
I think something is wrong with TEV it must be TES2 with orifice 3. If you not sure about tev setting put it on 2.75 turns from closing. Your SH must be 5-7K. You say that pipe is with ice 5 meters before compressor when t in room is -7C and pipe length is 40 meters. Did you measure SH till now. Is You suction pipe with insulation - it too long. Are you sure about correct position of TEV bulb - 2o'clock on 28mm pipe before equalization. Position of evap is it correct and fans rotations. Measure delta T on evap.

dont always assume that ice on a freezer suction line is floodback!!!