Student question

[WebRam]

I have been a member of your website for 3weeks now in hope of being able to
chat to someone online regarding a small problem i have. Unfortunately, I am
always the only person in the chat room.
This is why I have decided to contact you, in hope that you can help me out.

I am a 3rd year Architecture student from University College London.
Currently I am designing a butchers shop.

The design of the building revolves around the concept of using the heat
created by a 12m high cooling 'tower', to heat the main living spaces. I
have proposed using individual condensers and coils of varying sizes to heat
the rooms, acting like oversized fireplaces.

Is this idea feasable ?
Is there any technical data you could send my way to help me out?

I have a end of term evaluation in 2 days, so would appreciate a quick
response.
Thank you for your time.

Nicholas Wood

PS: Approx vol. of fridge = 120m3

[Peter_1]

It should have been better not to wait 3 weeks and then post your question 2 days before you need an answer.
You could have seen that there are regular posts each day in the forum.
Not everyboduy has the time to sit before his computer untill someone has an urgent question.
If you post it, we can read it on the moments we have some spare time to help you.
Communication these days??? We have mobile phone, fax, email, SMS and we never talked that less since.

Using the heat of a cooling tower??
How hot is the water? Do you need to upgrade it with compressers, running with a high COP to a higher temperature level?

12 m high, is this relevant for your case?

What do you mean with condensers and coils?
Different condensers is not that easy,it's in fact almost impossible.

Better should be making hot water and distribute this to a central AHU or separate watercoils in the rooms.

I need a lot more info before I can help you perhaps.

[Abe]

Why is Dez posting this and not the student??

[chillin out]

Abe,

Student must be shy, and sent a PM to the boss.

Nicholas,

No need to be shy, post any question you want and somebody should be able to help.

Re: chat room,

Most members have been on this site for a long time and I bet none of us have ever caught anybody on it.


Chillin

[Dan]

I suppose your idea is feasible. Heat recovery is very commonly applied where heat gained by refrigeration is put to a better use where heat is needed. Your idea's effectiveness will hinge upon many things, including the availability of heat when heat is required.

[aeb200]

Currently I am designing a butchers shop.

The design of the building revolves around the concept of using the heat
created by a 12m high cooling 'tower', to heat the main living spaces. ...........individual condensers and coils of varying sizes to heat
the rooms, acting like oversized fireplaces.

Living space in butchers shop??
12m high cooling tower? - In a butchers shop
Condensers and coils acting like an oversized fireplace??- in a butchers shop??

where is the meat going to be stored??
Where are the fridge display cases going??

You could use waste heat from storage fridges and display cases to heat the room - not very reliable though. You'd be better off with standard heat pump a/c unit. The reason that no one has condsidered 12m high cooling tower to heat(??) a shop is that it probably wouldn't work!!
Leave air conditoning design to a/c engineers and stick to drawing buildings-
Is this where the thread BLOODY UNI GRADS COMES FROM

[Brian_UK]

Re: chat room,

Most members have been on this site for a long time and I bet none of us have ever caught anybody on it.


Chillin

Never been able to log into the new chat room.

Had a chat with an Australian friend one evening on the earlier version but that's about it.

[saud khan]

lot of thing is possible i use to work for a firm specialise in heat recovery for swimming pools using the heat lost on the discharge air to re heat the water. it is not as simple as you put it a lot has to be taken into account
rate of water flow
temperature of the water
and so fort

[nickwood99]

Firstly, thank you for your repsonse. I feel i should elaborate.

At present the fridge sits in the middle of the building. As if it were a chimney. Quarters of beef are lifted to the top of the 12m high fridge, and in an archimedean screw system, make their way down to the bottom where the shop is. This is a timed process to allow for sufficient 'dry hanging'.

The calculated volume includes the access stairs that sit with the fridge. In essence, it is just a large cold store.

I would be interested to know whether one could, in theory, run one large fridge off of a series of condenser/coil systems. Using the heat produced to heat highly insulated rooms, working on a basis of heat retention rather than creation.

I also do not appreciate the commments about just drawing buildings. It is actually quite easy just to do that... i am trying to incorporate more interesting themes into my work.

Would also still appreciate some advice on where to get decent fridge diagrams/equations.


NICK

I you want a technical drawing of the fridge in question.. e-mail me at nik0983@hotmail.com

[Peter_1]

I also do not appreciate the commments about just drawing buildings. It is actually quite easy just to do that... i am trying to incorporate more interesting themes into my work.

Would also still appreciate some advice on where to get decent fridge diagrams/equations.

One, I appreciate your attitude that you wants to go a Little bit further the crowd expects you to go.
This will give you in real life that Little bit more advantage when looking for a job, wining a project, even if you're a Little bit more expensive, ...

Two...doing this with multiple condensers from different size...don't do it, it's to difficult to regulate and the main purpose of the plant is still cooling the meat,...

You may not try to cool with the intention of heating.
It's the same as some do when installing heat reclaim: let the compressors run at a high HP so that they can provide very hot water.
It's no worth the extra electrical energy.
Better let the compressers run at their normal HP or even use a lower HP due to the added condenser and let the compressers run with a higher COP and reheat it afterwards with conventional methods.

You have to see the heat as a usable waste of energy.
The first thing you have to take care of is that the cooling plant keeps running safe without problems.

If the cooling unit is a pack or a central unit, install a plate HE refrigerant/water and use the water to heat the spaces.
It's cheaper, much more reliable, better to control, less needed refrigerant, additional heat can be added or the system can be switched to a common heating system (oil, gas..) when there is no sufficient heat available.

I see you're living in the UK, so when you need the heat the most in the offices, the less heat is available.

[nickwood99]

sorry if i seem stupid but i think you may have explain it to me as if i were an 8 year old....

...do u mean it would work if all condensir coil systems were regularised?
...surely it works on the same principle as an abitoir i went to - the whole building is kept to 8 degrees celsius... they use heat produced to help with their hot water system

nick

ps: if it was obvious.. i am proposing the use of condensor/coil systems as radiators in the rooms that sit flush to the fridge tower,

[Dan]

sorry if i seem stupid but i think you may have explain it to me as if i were an 8 year old....

Nick, a sketch would help me to see what you are envisioning. Perhaps you should let us fridge guys be the 8-year-old. You have a good question and some sound instincts. I must say that Peter has provided a wonderful response to your original question.

...do u mean it would work if all condensir coil systems were regularised?

I am not sure what the word "regularised" means. But I like the concept.

...surely it works on the same principle as an abitoir i went to - the whole building is kept to 8 degrees celsius... they use heat produced to help with their hot water system

The amount of heat required to produce hot water is a small fraction of the heat required to heat living spaces.

[Peter_1]

How hot is the water coming from the tower?
Haven't received your drawing yet.
There is for me a difference between a condenser and a coil in the room. Perhaps that's only a language problem.

You have to eave the idea of different condensers, too many piping, too expensive, too many refrigerant in the system, too difficult to regulate...it will create problems which doesn't excist now,...

With water coils in the rooms, it will work perfect and you can use the wast energy the same way you intended to do, for the same purpose,... So why not go for this solution, your idea is a good idea.

We once made a proposal for a storage space at Brussels Airfield, very nearby BESC5240 's place,
Adelantex more specific.

They build a new complex with several spaces (I think there were +/-12 spaces)
There were also 2 or 3 freezers at -25°C, some cold rooms at -1°C (+/- 4) and then a lot of rather big spaces (+/- 6 or so of 30 x 15 ft x 18 ft high) which has to be kept from -1°C to 20°C, determined by the stored goods (could be living birds to fresh meat)

The technical advisers of the client had made a set-up with Daikin Chillers, cooling glycol, even for the freezers 100 x
They bypassed some warm returning liquid for the coldrooms.
There were also oil burners for heating the spaces.
There was no telemonitoring foreseen.

So we made anew proposal with a VFD controlled pack, connected to internet so that the supervisor could see at home the whole plant.
All the rooms were 3 pipe connected with the possibility to heat the indoor coils with hotgas together with the fans (heating the spaces and defrosting without fans where necessary), where some fans were VFD controlled to avoid excessive drought ( we taught on the animals)
The condenser could work also as an evaporator in case we had not enough wast heat available and we had foreseen also electrical heaters in the evaporators in case of in case of

We didn't won the job because we had to much comments on the original chiller set-up.

Added some pictures of a VFD controlled pack my son and I made end 2004 with a heat reclaim plate HE.
It's that large rectangle stainless steel piece between the small vessel. We store it in a reservoir of 3000 l.
The picture of the 3 small HE is instaleld by the plumber according to our drawings. It's for making up hot rain water (we may clean the trucks with rain water but not inside the building) for the heating of water (to 37°C) for the handwashing units in the factory and the 3th is for heating a small office under the pack.

[Peter_1]

And this is from a pack we made 14 years ago.

You can see some progress - at least I hope you see it - we made through the years. This was then very exceptionally, especially because packs were not that common those days.

The boilers came all from the scrapyard, the 2 coils are for heating the offices and for the cleaning water in the boilers. They're mounted behind the switch-cupboard.

I had the occasion to buy these two coils at a very low price because my supplier then should make the change to plate HE.

We needed to add some lines in the PLC program to let run the condenser fans each day some minutes. The first time it had to run, the bearings were stuck: they never had to run before.

The pack is made in a mathematical row 1 HP, 2 HP, 4 Hp, 7,5 HP, and an old Bock they had of 10 HP.
Even the old Bock which is now +/- 22 to 25 years old is still in place.
The Bock is for the freezer as you can see the suction line is going a separate way.
VFD's were then very expensive and I had then also not enouh experience to try this as the first one.

Notice, no oil separator, no oil floats, no equalising line and still the original compressers in place.

The PLC is going up in steps of 1 HP till the preset LP is at the setted level.

As you can see, they use the compressers also to dry towels Forgot to remove them when taking the pictures

[Dan]

Peter, that's the damndest thing I have seen in years!

So, how is it you get oil to the compressors?

[Peter_1]

Sorry I have to asks but damnedest is not in my dictionary. What do you mean with it?

I have to add we install now oil floats, oil separator and all the other stuff but sometimes I ask myself he question: why?

We have 4 packs running this way and the youngest is 12 years old and there was a compressor changed and I was quite amused when it happened.
BESC5240 remembers this story perhaps (Lessines): there was a gas shortage and the gas-alarm triggered. But nobody called us and let it run till they had a circuit breaker going out.
The biggest compressor was broken inside.
It was a Frascold/Carrier of +/- 7 HP. The pack was then +/- 7 years old.
The tech who repaired it - not a tech of me - said: "we never install such a compresses, they're cheap, not good, they're nothing worth...It even has no OSD on it and that's the reason why it failed. I will replace it with THE compressor, a DWM/Copeland"
He welded new brackets on the chassis, and adjusted the discharge and suction header for this news compressor by adding a T-junction on it and mounted the new compressor.... with an OSD of course because this was THE reason of the failure.

2 days later, they had a call again and the same tech went to the site again and his beautifully compressor was for the scrapyard. 2 days!!!
No oil in the sump.

He then said to the client this was because there were no oil floats, no oil tank, no oil separator...

Client was then so wise to say "Well, why did it last then 7 years without any problem, without all that 'oil stuff', we had a gas shortage which we neglected, that was our fault, but you replaced it with the best compressor available and it held only 2 days. Something else is wrong"

So client insisted that I should come over to discuss this before replacing the broken DWM again.

The OSD wasn't wired because this was not foreseen in the schematics with the Frascold (this compressor hadn't a OSD), there were no additional wires to the compressor. Well, if this is n't a reason to connect an OSD .....
The tech wasn't aware that a header and especially a suction header are not just T-junctions.

I all did this because an old Dutch tech, working for a big Holland company told me once: "If you calculate your lines the proper way, if you install them the proper way, if you make a suction and a discharge header according the rules and if the electrical control system is according the rules, and if your compressors are selected the proper way, then you can use many times the most basic setup: no oil separators, no oil floats, no suction accumulators, not all that fancy electronics, ...

This is a good start for some of us http://www.bitzer.de/_doc/k/kt-602-1.pdf
I read it in the past (the older versions of it) when I just strated at least 10 times.

I've seen packs which injected the separated oil direct in the suction header of the compressors.

So, as you see, it can be done the other way, without all that fancy devices, without all those electronics, and for the younger techs amongst us, even without the ability of connecting a computer to it.

This is just applying the basic rules which so many even don't know.
And that's also one of the reasons why this forum is such a good base for our industry: the older techs amongst us can give their experience to the younger ones.
But also even the not so old techs but those with that specific knowledge in their field: automotive, cascade, airconditioning, supermarkets..
For someone not in the job, they're all the same if there's a compressor in it. But we know better, isn't it.

PS for Dan, I just noticed now that you're 'the ' Dan from Florida. But your avatar has changed, reason why I hadn't noticed it at first.

[lana]

I have been a member of your website for 3weeks now in hope of being able to
chat to someone online regarding a small problem i have. Unfortunately, I am
always the only person in the chat room.
This is why I have decided to contact you, in hope that you can help me out.

I am a 3rd year Architecture student from University College London.
Currently I am designing a butchers shop.

The design of the building revolves around the concept of using the heat
created by a 12m high cooling 'tower', to heat the main living spaces. I
have proposed using individual condensers and coils of varying sizes to heat
the rooms, acting like oversized fireplaces.

Is this idea feasable ?
Is there any technical data you could send my way to help me out?

I have a end of term evaluation in 2 days, so would appreciate a quick
response.
Thank you for your time.

Nicholas Wood

PS: Approx vol. of fridge = 120m3

Hi dear student,
I suggest you go to the mechanical engineering department at the UCL and ask for Dr. William Suen. He can help you. He is the MSc. Refrigeration and Airconditioning course director.
Tell him that one of the twins introduced you.
Cheers.

[US Iceman]

Hi Peter,

I all did this because an old Dutch tech, working for a big Holland company told me once: "If you calculate your lines the proper way, if you install them the proper way, if you make a suction and a discharge header according the rules and if the electrical control system is according the rules, and if your compressors are selected the proper way, then you can use many times the most basic setup: no oil separators, no oil floats, no suction accumulators, not all that fancy electronics, ...

I agree with the old Dutch tech. I have installed multiple compressors on a common suction & discharge line and it worked well. It does take some thought and consideration, but it does work.

[Dan]

Sorry I have to asks but damnedest is not in my dictionary. What do you mean with it?

Sorry for the slang. I meant:
Wildly original or creative. Unlikely. I am surprised that you are achieving oil return in the semi's on the right, and the mounting of the water heaters is striking... then drying out the towels. It made me smile, that's all.

[US Iceman]

The compressor heads also make nice glove warmers in the winter.

[chillin out]

I agree with the old Dutch tech. I have installed multiple compressors on a common suction & discharge line and it worked well. It does take some thought and consideration, but it does work.
Reply With Quote

Thats all very well untill something goes wrong with the system, like short of gas, undercondensing, .......

You then have a case, coldroom or whatever full of oil.

Chillin

[Peter_1]

Chillin out, do you think all this never happened in the past? And still the original compressors are in place as you can see on the picture.
As I said, the Bock is even half your age.

Another example: I'm now more then 20 years in the business and I never installed a suction accumulator on a freezer compressor.
Some install on a freezer with a single condensing unit always an oil separator. Why? Never installed one on a single unit. If you have tot do this, then there's something else wrong.

Saw many times a siphon on the outlet of a single condenser on the roof.
If I asked the techs why they did it, their answer then was: "We're doing it always this way"

Saw a discharge line on a pack +/- 60 ft high with at least 6 siphons in it. I asked them why and their answer was "if you go up, then you always need siphons"

One tech said and this one knows his job and know what he's talking about: "I'm doing it because it's drawn this way but it's as stupid as it can be. We only need one just, perhaps a bigger one after the compressor or install a check valve."

[Dan]

What are these siphons you refer to Peter? Traps with drains into suction?

[Peter_1]

I meant an oil trap.

So they installed allways an oil trap at the outlet of the condensor, and also on a site 6 oiltraps in the vertical discharge line going to the condensor, preventing oil falling down to the compressor again and to avoid liquid migration to the compressor valves.

[Dan]

And oil trap at the OUTLET of the condenser? I could use the word "damnedest" to describe an oil trap on a condenser outlet.

[chillin out]

Another example: I'm now more then 20 years in the business and I never installed a suction accumulator on a freezer compressor.

Neither do I.

Some install on a freezer with a single condensing unit always an oil separator.

I work on supermarket plant which have long pipe runs, when they go s.o.g. then it will leave you with the problem with getting the oil back to the cond unit.

I agree, if the pipe size is correct then it will come back itself, but not in the short space of time I am on site. I like to leave my systems working 100% before I depart, and not hope for the oil to come back in its own time.

It may seem pointless to many to fit oil seps, but when there is a problem with the system (which there will be at some time of its life) it will save a lot of problems.


Chillin

[Peter_1]

I work on supermarket plant which have long pipe runs, when they go s.o.g. then it will leave you with the problem with getting the oil back to the cond unit.

I agree, if the pipe size is correct then it will come back itself, but not in the short space of time I am on site. I like to leave my systems working 100% before I depart, and not hope for the oil to come back in its own time.

It may seem pointless to many to fit oil seps, but when there is a problem with the system (which there will be at some time of its life) it will save a lot of problems.
Chillin

I worked in the past together wit BESC5240 on several supermarket systems for Carrefour, Belgium largest supermarket chain.
We even installed the first VFD controlled screw (Bitzer) pack for Carrefour.

We calculated together a whole supermarket, from price to line section, electrical switch-cupboard, meetings afterwords (if it was in French, then BESC was at his best), ...
BESC5240 made the first PED statement for Carrefour (he's much more patient then I am for this sort of jobs)

BTW, what's s.o.g.?

It may seem not only pointless...no...it is pointless.
Why 6, why not 14, why not 2 proper sized?
Ever thought at the additional friction this gives.

When the system is proper designed and the oil is coming back the first weeks or months then the oil will come back as long the system is running. Perhaps when there is gas shortage there an be some problems but then the problem with counters cooling not that well any longer will arise much faster then oil problems on the compressors.

The pictures are the perfect prove that it can work also the other way, since +/- 14 years.

And what they also told me in the past: that a pack must consist always of compressors of the same size.

[chillin out]

BTW, what's s.o.g.?

Short Of Gas

Perhaps when there is gas shortage there an be some problems but then the problem with counters cooling not that well any longer will arise much faster then oil problems on the compressors.

I agree but when you put the gas back in it will take some time for the oil to come back.

And what they also told me in the past: that a pack must consist always of compressors of the same size.

I have many packs with differant sized comps inside. Its all to do with the control you have over them.

Why 6, why not 14, why not 2 proper sized?

What do you mean?

Chillin

[US Iceman]

This is a really interesting discussion. Some manufacturers offer "items" for sale, that are supposed to provide some protection, or cure some problem.

The main concern with using these, is that they become crutches for lack of proper system design. If these devices are so important, how did we design systems properly before the devices were "invented"?

There is too much of a tendency in refrigeration today to use a "cook book" method for designing system. Use this, use that, maybe size the pipes, but pay no attention to how the pipe is installed.

Most of these problems can be addressed by proper piping practices and well designed pipe sizes. The link Peter posted was a very good example of how to pipe the system correctly.

The use of the traps in the discharge line for every 10 ft of vertical elevation change is another valid point.

For a similar reason, this is why you need dual suction risers for a vertical suction line going up (when used with capacity unloading of compressors).

These are all required for oil return for different reasons.

The clearance tolerances on the semi-hermetic compressors are so good that excess oil carryover is not a big problem in my opinion.

Can someone explain what undercondensing means? Is this supposed to mean the condensing temperature is too low? I suppose overcondensing would be a higher than normal condensing temperature? Where did this type of description come from???

[US Iceman]

This from another thread discussing a similar problem.

http://www.refrigeration-engineer.co...ead.php?t=3526

[chillin out]

I use the term 'undercondensing' to mean that pressure in the liquid line will still be too high.

'Overcondensing' meaning pressure too low.


Chillin

[dogma]

Living space in butchers shop??
12m high cooling tower? - In a butchers shop
Condensers and coils acting like an oversized fireplace??- in a butchers shop??

where is the meat going to be stored??
Where are the fridge display cases going??

You could use waste heat from storage fridges and display cases to heat the room - not very reliable though. You'd be better off with standard heat pump a/c unit. The reason that no one has condsidered 12m high cooling tower to heat(??) a shop is that it probably wouldn't work!!
Leave air conditoning design to a/c engineers and stick to drawing buildings-
Is this where the thread BLOODY UNI GRADS COMES FROM

LOL. At least there are people out there that know where i'm comming from LOL

[dogma]

I don't know, but wouldn't you first design the building then incorporate your HVAC?? I was under the impression unless your designing a "green building" the building design would come first, then enlist the advice of a HVAC engineer to design the system.

No wonder there are so many dodgy systems.

[trustaircon]

hi this senthil

[trustaircon]

I have been a member of your website for 3weeks now in hope of being able to
chat to someone online regarding a small problem i have. Unfortunately, I am
always the only person in the chat room.
This is why I have decided to contact you, in hope that you can help me out.

I am a 3rd year Architecture student from University College London.
Currently I am designing a butchers shop.

The design of the building revolves around the concept of using the heat
created by a 12m high cooling 'tower', to heat the main living spaces. I
have proposed using individual condensers and coils of varying sizes to heat
the rooms, acting like oversized fireplaces.

Is this idea feasable ?
Is there any technical data you could send my way to help me out?

I have a end of term evaluation in 2 days, so would appreciate a quick
response.
Thank you for your time.

Nicholas Wood

PS: Approx vol. of fridge = 120m3

hi this senthil

[Peter_1]

Senthil, welcome, may i ask to introduce you in the special section 'NEw to Re' and mowe your posts to there.
Try also not to double-post.

[Elliza]

hihihi..
students question, oh wow...
does anyone have a thermodynamic properties for HC-12? n the HC-12 that i mean is hydrocarbon blossom have u ever hear that?? coz i really need it for my final project report, thx
nice to meet u guys