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Josip
12-01-2007, 11:09 PM
Hi, all :)

thank you, US Iceman, to open this sub-forum. It is very interesting.....

all this started here:

http://www.refrigeration-engineer.com/forums/showthread.php?p=57631#post57631



..... What started out as a discussion on lowering head pressure and itís implications has become a discussion on total system optimization! And it seems to be a topic that a lot of people are interested in. With the ever rising costs of energy and the push for a greener planet, I wonder if this would make a good topic for a forum or sub-forum.

What Sergei mentions about defrosts going from twice per day to once per week has become quite typical in plants that incorporate smarter controls and/or keener operators. Evaporators that require 2 defrosts per day during that one hot week in august can often get away with one or two defrosts during the winter months. This gets back to the problem of fixed setpoints often being the ďworst caseĒ setpoint. If two or three defrosts are needed in the summer, thatís where the pins are left in the time clock. If -25 suction kept the rooms cold in August, thatís where the suction is left all year. If one evaporator requires 145# for defrost, thatís where the pressure switches are set. Itís obvious that a lot of systems have a lot of room for energy usage improvements

Another great up-side to long durations between defrosts is you can float the head pressure lower for a longer period of time thus enhancing energy savings.

Yes, I have to agree there is a lot of room for energy savings by usage improvements, but....

we are witnesses to the war between companies to get the job (speaking here mainly about industrial installations of either HVAC or refrigeration plants) using methods with no scruples to gain profit. They are ready to reduce the price, quantity, quality, everything to get the job and to sell sh*t with words "we are selling the best energy savings technology, innovative energy savings system, fully automatic energy savings system no needs for operators, maintenance.......and so on.


On opposite side we have our customer, usually without any knowledge (except acceptable price) about quality energy savings system also often short in budget, but looking for a good plant.

Many times this "innovative" technology "innovators" sell with very high prices too:eek: yes, to the people with unlimited budget but with very limited brain.

Nice bait/snatch for sharks around.


How to win in that war? How to sell good designed, optimized plant, usually expensive to customer buying only cheap things.

We cannot win if we cannot stop global heating and climate changes with waste energy and very soon there will be only loosers on this planet.

What do you think where to start? What to do?

Best regards, Josip :)

Brian_UK
12-01-2007, 11:19 PM
I sometimes wonder whether in the coming years, will it be a requirement to fit an 'energy meter' to new installations so that the "energy saving" can be proven to the customer.

I used to work for a company that supplied a new -20įC cold store to an ice cream manufacturer. When during the commissioning tests he found out that the store could be taken down to -27įC then that was the temperature that he wanted it to run at.

We never could convince him of the energy wastage that he was performing, but you can't always win.

US Iceman
12-01-2007, 11:32 PM
Many times this "innovative" technology "innovators" sell with very high prices too:eek: yes, to the people with unlimited budget but with very limited brain.


yep, that happens a lot. Most of the owners do not understand refrigeration. So they depend on someone to do this for them.

A lot of consulting engineering firms are going into industrial refrigeration using the ASHRAE books to design systems. Some of these I have never heard of before, but the are selling designs.

That means the owner will probably get a system designed like an HVAC system; cheap and very little documentation.

At the same time, a lot of contractors are finding industrial refrigeration as a way to make a lot of money (or just something else to do:confused: ).

Somwhere, the combination of this wll make a lot of work for those who do understand how a system works and the requirements.

This does not have anything to do with system optimization, but rather selling optimization on someones part.

All too often the different methods of optimizing systems are negated by someone who says " that won't work". Unfortunately, that person doesn't understand but he can start a big mess with the owner.

Then you look like a crazy person with wild ideas, so the owner thinks you are experimenting with his money.:rolleyes:

The funny thing is though, the person who does not understand will have all sorts of reasons why he is right.

These reasons start out with; That won't work... to another one of my favorites; We tried that once before....

Try getting someone to lower their discharge pressure when they always run it like it is in summer.:p

US Iceman
12-01-2007, 11:39 PM
When during the commissioning tests he found out that the store could be taken down to -27įC then that was the temperature that he wanted it to run at.


A lot of people want to run their systems as cold as they can get them thinking this helps improve the food quality. Ice cream and fresh fish are the only two I know of that seem to fit this (also consistent low temperatures).

I like the idea of an energy meter and these are available.

All too often though, the owners are sold an energy saving design that never materializes.

There was a recently installed large ammonia system here in the US that was promised to be "state of the art". Well it was, if you used 1960's design as the comparison.:D

Latte
12-01-2007, 11:49 PM
Dont Think energy consumption comes into it unless its a large install (Supermarket Pack) for instance. Everything is price driven.

Lets take an example that we can relate to
probably 90% of people when choosing a van look at what they get for their money
£15,000 (example) for a standard transit or
£15,000 (example) for a vauxhall with a/c, elec windows, mirrors and a 6 speed box

how many people sit down and work out fuel consumption over the life of the vehicle

Regards

Fatboy

Brian_UK
12-01-2007, 11:49 PM
Well it was, if you used 1960's design as the comparison.:D
I never thought of ammonia as 'Art Deco' :D

US Iceman
12-01-2007, 11:56 PM
You would be surprised if you would have seen some of the old gauge boards that used to be installed in the older engine rooms.

Some of these old relics are actually quite fancy with gauges large enough to read from a long distance.

US Iceman
13-01-2007, 12:03 AM
I don't have any experience on the new supermarket packs. All of the supermarket work I used to do had single condensing units per case line-up.

From what I know, supermarkets are like gas stations. You have to sell a lot of groceries or gasoline to make even a small amount of money.

The one thing supermarkets have going for them though is, any energy savings adds a tremendous amount of net income. Saving a few dollars here and there is the same as selling an extra cart load of groceries.

Supermarkets are energy hogs just like a lot of larger systems. There is so much that can be done, if a lot of people will quit saying it can't be done.:D

Andy
13-01-2007, 11:33 AM
I don't have any experience on the new supermarket packs. All of the supermarket work I used to do had single condensing units per case line-up.

From what I know, supermarkets are like gas stations. You have to sell a lot of groceries or gasoline to make even a small amount of money.

The one thing supermarkets have going for them though is, any energy savings adds a tremendous amount of net income. Saving a few dollars here and there is the same as selling an extra cart load of groceries.

Supermarkets are energy hogs just like a lot of larger systems. There is so much that can be done, if a lot of people will quit saying it can't be done.:D


We have our own design for a supermarket pack. Use four Bitzer Octagon compressors of roughly even sizes, fit an inverter on the lead compressor and use the new Danfoss AK2 pack controller.
This we fit as standard on all our supermarkets, mostly with electronic valves and controllers from Danfoss.

We also give the option of heat recovery:)

Not everyone gets what we are trying to do, but word is getting around;)

Kind Regards Andy:)

laf100
13-01-2007, 01:57 PM
On the A/C side, I get frustrated with IT managers who insist that the servers will crash if the temp is not maintained at 18C! The aircon is there to stop heat build up, not to keep processors and drives cold. I am on a personal mission to encourage computer room operators to set the A/C for around 25C (when there is no personal occupancy). I have been to small comm's rooms where the A/C has failed, and the temp risen to 32C, and the servers have still not "fallen over"!

US Iceman
13-01-2007, 02:41 PM
I have only worked on one A/C system in a IT center. This center used under floor air distriution to allow the air to flow up through the servers. There have also been some recent publications I believe on IT center design to better calculate the heat loads and air distribution.

I suspect their concern is not that the system will quit, but to prolong the life exectency and reduce server crashes.

I would think electronics are heat sensitive, so cooler temperatures would help. Witness the trend in PC cooling systems to overclock the processors.

I have also seen some articles where the chip manufacturers are utilizing thermosiphons directly attached to the heat sink on the processors to aid cooling.

I wonder what will happen when high temperature super conductors become available???

US Iceman
13-01-2007, 02:43 PM
Not everyone gets what we are trying to do, but word is getting around;)


I think that is a big part of the problem Andy. People need to understand why we want to do something. It's a long education process to be sure...

autt
13-01-2007, 04:59 PM
Many of you are lucky to live in a good environment, but things around me is not so good, corrupt, pollution of air, water, food, and many many other, that will damage every body, and the next generations of whole country.

I always think about this, why things getting worse? My result is, that the bad is not punished, the good is not awarded. We have not build up the reasonable rule.

I mention this because it is the same with optimization, to punish the bad, and to award the good, let the system running(or finding calculation process) by itself, then we get the best, or to say near the best.

What we do in calculation is to tell the program what is bad, what is good, and build up the punish and award mechanism.

Although optimization includes many aspects as equipment cost, lifetime cost, scheme, arrangement, thermal and dynamic control performance etc, and these all can be converted to cost, as common of price.

Certainly many of these can not be converted in calculation, we need to do them in other way.

Also detailed process needed for discuss, but things are really possible.

This is my personal thoughts, please comments if interested.

joe magee
14-01-2007, 05:53 PM
Just reading about energy savings in markets. Here in southern cal saving energy is a big deal. The company I work for has a department just to do that. I will go into a market and do the recommishioning . On racks we float head and suction, put drives on condensers that didn't have them. Night setbacks on hvac,antisweat adjustments ,lighting etc.

I received info that we are going to install drives on the lead compressors. Any other ideas?:)

Regards,
Joe Magee from over the sea.

Paulajayne
15-01-2007, 01:55 PM
On the A/C side, I get frustrated with IT managers who insist that the servers will crash if the temp is not maintained at 18C! The aircon is there to stop heat build up, not to keep processors and drives cold. I am on a personal mission to encourage computer room operators to set the A/C for around 25C (when there is no personal occupancy). I have been to small comm's rooms where the A/C has failed, and the temp risen to 32C, and the servers have still not "fallen over"!

The 18C is a temp that is set for the machines not the pax. cooler = faster for processors.

Many large servers have temp sensors inbuild and will shut the machine down at a preset temp. HP mainframe servers are set at 30C.

So sorry your 25C is too high.

Paula

Sinke
13-07-2007, 09:53 PM
What do you think where to start? What to do?

Best regards, Josip :)[/QUOTE]

...nema tu pomoći Josipe,priroda će naći načina da nam vrati za sva sranja što smo napravili...
...I think is not possibile,the human nature is basic on destruction...
...God help us....

Josip
08-09-2007, 05:34 PM
Hi, Sinke :)


...nema tu pomoći Josipe,priroda će naći načina da nam vrati za sva sranja öto smo napravili...
...I think is not possibile,the human nature is basic on destruction...
...God help us....

Sorry for my late replay but I was absent for a very long time and somehow miss your post.

Of course the mighty mother nature should make her invoice for all wrong we did against her. God help to our children...


Best regards, Josip :)

Lowrider
08-09-2007, 05:57 PM
25 dgr C for a server room is indeed too high!

We always set them at 21 or 22 and have at least one complete machine as back-up if one should fail.

We commision a lot of server rooms, always with multiple downcooler CCU's, with humidification and de-humidification. Installation is done by a third party.

And yes, it's hard to get any one on board when saying an extra machine, an extra compressor (i.e. a swing in a rack), an inverter driven condensorfan or anything else that would improve reliability or energy consumption on any refrigeration aplication to a layman.

Samarjit Sen
08-09-2007, 06:48 PM
Josip,

It is nice to meet you after a long absnce.

Regards

Josip
09-09-2007, 08:35 AM
Hi, Samarjit :)

Yes, I've been absent for a long time. Many times without possibility even to read some posts on RE forum. Hope to be present more here now, but that depends on some other assignments....still must work and travel around a lot, the same as you;)

Best regards, Josip :)

The Viking
09-09-2007, 11:56 AM
25 dgr C for a server room is indeed too high!

We always set them at 21 or 22 and have at least one complete machine as back-up if one should fail.



First, I fully agree that there should always be backup.

But, where are your machines measuring the room temperature? In the return air?
If so, and assuming that the IT room/suite/hall is correctly designed, you are controlling on the warmest air in the room.
The IT equipment should have the coolest air supplied to their air intakes, then heat it up and recirculated back to the AHU, yes?
So your set-point of 21 would in fact supply air to the IT equipment at around 10-13 degrees+the mixup with the room air, say a resultant at around 16-18 degrees.

See the attachment for what the server manufacturers really are asking for..... quite interesting.

And all of it is specs for the supplied air, they don't give a toss about the air behind their machines, in fact most of them has temperature controlled fans and will not supply less than ~30 degrees out the back.

Lowrider
09-09-2007, 05:32 PM
Indeed the resulting room temperature will be somewhere around 17. And yes the temperature is measured in the return air.

Still the problem isn't the temperature, just the rate at which it increases that is causing the problems in the serverrooms.

And so we set them at 21 and if there's a problem, the room and the backup unit give some room for error and not cause the servers to go down.

Buckiesr
09-11-2007, 03:03 AM
Who sells these energy meters and what are they?
I just read an article showing the use of photohelic sensing for differential pressure across the evaporator coil to trigger a defrost cycle. I think he called it a demand defrost. When the frost builds up enough to create the set point delta "P" it triggers the defrost timer. he also discussed using the Delta "P" to end the hot gas as soon as the Delta"P" comes back into the proper pressures again. The defrost timer cycle runs through the pump out and then kicks in a Time delay relay along with the hot gas cycle, which will continue until it hits the low delta set point or in case it doesn't reset the TDR times out and moves on to equalize, and fan delay. I don't remember but it seems to me you need to keep a fan operating to measure the Delta "P" during the hot gas cycle. Maybe you could switch to a second photohelic ( I don't know for sure how to spell this word.),and measure natural draft through the coil.
wm

jose regueiro
10-11-2007, 11:30 PM
Until regulations impose to put what actually save energy, it will make whatever you want. If the customer wants to save energy, which spent installing lots of money. Each installation is particularly unique. Statistics in time will say what is the best system. It will be necessary to record all data on a daily basis of systems to generalize. In structural design is supposed what's going to happen. Using simulators for speculation and Technology safe

John Hunter
21-11-2007, 05:18 AM
Us Iceman you mention large pressure gauges , I remember the days when we had these large gauges, large valves with large handles, large compressors with equally large flywheels. One plant I was associated with years ago had one of the labourers go round just about every day to pollish every thing that would polish. Energy efficiency was not even a figment of imagination . Jees I must be getting old.

US Iceman
21-11-2007, 09:23 PM
Hi John,

Yep, I've seen several older plants where these console gauges were still in use. They did not have gauges/transmitters everywhere like we do today.

Some of these old systems were very impressive as you say. My grandfather told me the brewery back home had large glass windows on the main street (next to the sidewalks) so that the engine room could be seen by pedestrians.

Everything was nicely painted and polished for presentation.

Some still do this today, although they tend to hide the engine rooms at a location away from the general public now.

It's surprising, but even then I think they were concerned about energy conservation. They used to purge off non-condensables, keep the head pressure down, and used to use stills to keep water out of the ammonia.

I think a lot of these "new" discoveries are due to the training programs being cutback due to accountants trying to save money.:rolleyes:

TXiceman
22-11-2007, 04:30 AM
I think a lot of these "new" discoveries are due to the training programs being cutback due to accountants trying to save money.:rolleyes:


We are in trouble when the accountants and lawyers start designing th equipment.

I do not have a law degree and thus do not practice law. Lawyers should be so kind as to not practice engineering....

Ken

Josip
24-11-2007, 03:24 PM
Hi, all :)


We are in trouble when the accountants and lawyers start designing th equipment.

I do not have a law degree and thus do not practice law. Lawyers should be so kind as to not practice engineering....

Ken

Yes, Ken agree with you...maybe to contribute a little to this discussion...

...this thread is 10 months old so far..... I have changed, a little, my view about situation regarding controls, safety and running of refrigeration plants...

Thanks to modern age today we can utilize a lot of new technologies to reduce power consumption and to monitor complete state of our plant....but we forgot about operators-human beings......as you know I'm traveling around viewing different refrigeration plants and I can say the owners/managers does not invest enough into education of operators (fluctuation of manpower is huge, but mainly of non educated or at least not enough educated manpower - less to spent for salary:rolleyes:), just giving a complete trust into computers (machines observe machines) to run and take care about all,....but without a good operator taking care about everything there is no any plant which can run for a long time.....

This is my humble opinion, maybe not right, but there must be some truth within;)


Best regards, Josip :)

TXiceman
24-11-2007, 05:11 PM
Josip, I agree. You can put the fanciest and most costly computer controls on a plant, but you still need a very knowledgeable operator to keep an eye on things. The computer will not detect an oil leak, ammonia leak or that strange noise until it is too late.

Even with the computer data logging, I still insist that an operator makes a round and check the unit over physically on a regular basis.

Next issue is the use of all of the data logging. It means absolutely nothing if you do not have someone that knows how to interpret the data. He has to be able to determine if a rise in pressure or temperature is due to a change in operating conditions or is he seeing the beginnings of an equipment problem.

I see to many plants that file reams of paper and never look at it. Months later they are down with a problem and when you ask to see the logs....we have to find them is the answer. And you find the problem has been weeks in development...no one ever bothered to look at the data.

My Grandpa used to say that you never trusted bankers, lawyers and skunks....

Ken

US Iceman
24-11-2007, 05:50 PM
My Grandpa used to say that you never trusted bankers, lawyers and skunks....


And if I might add to your grandpas list...snakes and control systems.

Either one is fully capable of biting you when you least expect it, or when you just become comfortable with them.



...but without a good operator taking care about everything there is no any plant which can run for a long time...


There is not substitute for experience and a set of human eyes, ears, & nose.

And for accountants purchasing refrigeration systems I have nothing positive to say...

Core4 Guy
17-02-2008, 08:45 PM
On the A/C side, I get frustrated with IT managers who insist that the servers will crash if the temp is not maintained at 18C! The aircon is there to stop heat build up, not to keep processors and drives cold. I am on a personal mission to encourage computer room operators to set the A/C for around 25C (when there is no personal occupancy). I have been to small comm's rooms where the A/C has failed, and the temp risen to 32C, and the servers have still not "fallen over"!


Data Center Guys...

Here ya go I finally found a data center guy. The cooling on a typical data center unit work most cost effectly at 68F 50%RH (IT Industry Standards). If you raise the setpoint to 72F / 50%RH more latent heat is removed my the coil. Causing the humidifiers to operate more anding kW into the room. This is a visious cycle for data centers. Keep the room at 68F is possible of design the system to act only a a sensible cooling system only. Total Redesign and New Equipment. Can save a total of 30% of the compressor and humidifier energy.