I've been out if the refrigeration side of the business for a few years now. The other day someone asked me to look at their 160 ton rack unit which is about seven years old. I looked inside and there are three Copeland Semi-Hermetics'..."really." Why do refer manufacturers’ still use fifty year old inefficient technology. Why are A/C manufactures forced to come up with cutting edge technology and refrigeration manufactures not????
Why do refer companies still use Recip compressors???
basprofessional
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I've been out if the refrigeration side of the business for a few years now. The other day someone asked me to look at their 160 ton rack unit which is about seven years old. I looked inside and there are three Copeland Semi-Hermetics'..."really." Why do refer manufacturers’ still use fifty year old inefficient technology. Why are A/C manufactures forced to come up with cutting edge technology and refrigeration manufactures not????
Money.
Free market.
You can buy whatever you want. That guy wanted semi hermetics. Reliable and proven technology. Compressors that if properly maintained can run for decades.
Oh, and don't sell copeland short: the Copelametic has been around since the late '30s.
Free market.
You can buy whatever you want. That guy wanted semi hermetics. Reliable and proven technology. Compressors that if properly maintained can run for decades.
Oh, and don't sell copeland short: the Copelametic has been around since the late '30s.
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You can rebuild a semi-hermetic.
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Supermarkets have been opting for a number of different compressor types other than recips for many years now including screws and scrolls.
I saw one of the first stores to use screw compressor racks back in 1977, so that goes back a ways.
Shortly after scrolls were introduced for air conditioning application about 20 years ago, designs were produced for refrigeration, so by the mid-90s we started seeing stores with single and paralleled scrolls systems.
Also, recips design hasn't remained stagnant all this time. Copeland brought out their Discus compressor around 1982 or so...with a much improved top end which allowed for up to 25% increases in capacity for the same displacement and up to 16% energy efficiency gains.
Markets have always been sensitive to capital expenditures, operating costs and maintenance expenses. Heavy iron has always delivered a reasonable balance of all three. In the future however, I think scrolls will likely win out in spite of their lower life expectancy as manufacturing costs rise and our society's throwaway mentality grows.
I saw one of the first stores to use screw compressor racks back in 1977, so that goes back a ways.
Shortly after scrolls were introduced for air conditioning application about 20 years ago, designs were produced for refrigeration, so by the mid-90s we started seeing stores with single and paralleled scrolls systems.
Also, recips design hasn't remained stagnant all this time. Copeland brought out their Discus compressor around 1982 or so...with a much improved top end which allowed for up to 25% increases in capacity for the same displacement and up to 16% energy efficiency gains.
Markets have always been sensitive to capital expenditures, operating costs and maintenance expenses. Heavy iron has always delivered a reasonable balance of all three. In the future however, I think scrolls will likely win out in spite of their lower life expectancy as manufacturing costs rise and our society's throwaway mentality grows.
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Recips used in refrigeration
I've seen scrolls on some refrigeration systems and I've heard of screws on others. However, it seems that A/C companies are forced to go with the scrolls because of the higher efficiency standards. In addition, refrigeration must have higher operating cost because of their run time. I would think that customers would want to go with the systems that cost less to operate. It just seems that the same efficiencies standards do not apply to refrigeration?
I've seen scrolls on some refrigeration systems and I've heard of screws on others. However, it seems that A/C companies are forced to go with the scrolls because of the higher efficiency standards. In addition, refrigeration must have higher operating cost because of their run time. I would think that customers would want to go with the systems that cost less to operate. It just seems that the same efficiencies standards do not apply to refrigeration?
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Just for comparison, I extracted some performance data from the Emerson Website.
At the standard rating point for LT refrigeration is -25ºF SST/105ºF SCT and selecting various compressors in the 10-20,000 Btuh range, I found their EER (Btu/Watt).
*Scrolls are available with liquid injection resulting in significantly higher EERs.
At the standard rating point for LT refrigeration is -25ºF SST/105ºF SCT and selecting various compressors in the 10-20,000 Btuh range, I found their EER (Btu/Watt).
Copelaweld.....EER=4.1
Copelametic....EER=4.4
Scroll.............EER=4.6 *
Discus...........EER=5.2
Copelametic....EER=4.4
Scroll.............EER=4.6 *
Discus...........EER=5.2
*Scrolls are available with liquid injection resulting in significantly higher EERs.
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recips
Interesing, I wouldn't have guessed that about scrolls. Does that go for screws? I also assume water cooled is it more cost effictive to operate instead if air cooled?
Interesing, I wouldn't have guessed that about scrolls. Does that go for screws? I also assume water cooled is it more cost effictive to operate instead if air cooled?
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Water cooled is generally more efficient, solely because it allows you to operate at a lower saturated condensing temperature (SCT) at max summer design conditions. As for its cost effectiveness, that would depend on what you're using for a cooling water source and the cost of water in your area. Running straight city water is the most expensive (if not illegal).
Cooling towers and evap condensers require a lot more maintenance than an air-cooled condenser and they also use a significant amount of makeup water for the evaporative process and also need a strict water treatment program...so you'd have to sit down and figure all that into their cost of operation.
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And Copeland is not the only outfit breaking out the sliderules. Bitzer is making some fairly bold claims as well. I've mostly only seen them peppered through a few Costco's, and one mom-n-pop with an OEM Hussmann rack, but they seem to be holding their own.
I think as long as there is a demand, manufacturers will continue to be clever and creative.
I think as long as there is a demand, manufacturers will continue to be clever and creative.
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Recips
Thanks for the responses it clears up a few questions I had. One last question, I understand it's more efficient to run with one large rack instead of a bunch of smaller compressors. Does anyone know how to determine how much energy will be saved converting a number of smaller tonnage units to a large rack? For example, if a customer has a bunch of 1 to 5 ton units and their replaced with a larger rack how much would be saved? Is there a guide line to determine the savings?
Thanks for the responses it clears up a few questions I had. One last question, I understand it's more efficient to run with one large rack instead of a bunch of smaller compressors. Does anyone know how to determine how much energy will be saved converting a number of smaller tonnage units to a large rack? For example, if a customer has a bunch of 1 to 5 ton units and their replaced with a larger rack how much would be saved? Is there a guide line to determine the savings?
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When parallel rack systems were first being introduced back in the 1960s, I recall seeing operating cost savings claims of around 20%...but I have nothing to back that up except for my retreating memory.
Emerson's Product Selection Software has an energy analysis program which I believe one could use to do a comparison, but it would take a lot of input to define all the parameters involved.
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Here's a recent Copeland AE Bulletin which gives some very involved details regarding vapor injected low temperature scrolls: View attachment 211792
Note the 60+% capacity increase possible using VI. I'll have to use their Product Selection tool to get an idea of what the EERs might be.
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Re: Vapor Injected Scrolls
Looking at the performance data for a ZF18K4E-TF5 and its vapor injected version, the ZF18KVE-TF5, I found at -25ºF SST/105ºF SCT with R404A the capacity increase to be 60% with a resulting increase in power of only 20%. The EER went from 4.4 to 5.9 Btu/watt.
Not too shabby.
Looking at the performance data for a ZF18K4E-TF5 and its vapor injected version, the ZF18KVE-TF5, I found at -25ºF SST/105ºF SCT with R404A the capacity increase to be 60% with a resulting increase in power of only 20%. The EER went from 4.4 to 5.9 Btu/watt.
Not too shabby.
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Scrolls
I'm checking the information you sent me and thanks for sending it. However, looking it over briefly I would assume the condenser coil needs to be a little larger in this application? Also, I assume that regular scrolls are less efficient than reciprocating compressors on low and medium temperature applications? I assume that higher temperature systems like Air Conditioning the regular scroll is more efficient?
I'm checking the information you sent me and thanks for sending it. However, looking it over briefly I would assume the condenser coil needs to be a little larger in this application? Also, I assume that regular scrolls are less efficient than reciprocating compressors on low and medium temperature applications? I assume that higher temperature systems like Air Conditioning the regular scroll is more efficient?
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I'm using their 105ºF SCT rating points solely because that's the ARE standard. Certainly, for an air-cooled system with typical condensing temps of 115ºF-130ºF or so the numbers would change a bit, but the general relationships between types of compressor would basically remain the same.
I wouldn't assume that a current OEM, Resi A/C production scroll would beat out a Discus...as long as we were comparing apples to apples.
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That is reliable and very efficiently run on a large rack instead using smaller compressor.
That is reliable and very efficiently run on a large rack instead using smaller compressor.
Rack have better run time as well.
We put in a system with 2 5HP compressors on LT and 2 5HP compressor on MT. Only had one condenser. Engineer said it could be up to 60% more efficient than factional HPs. Plus piping was easier and no heat load in an already hot kitchen. PM was a breeze.
We put in a system with 2 5HP compressors on LT and 2 5HP compressor on MT. Only had one condenser. Engineer said it could be up to 60% more efficient than factional HPs. Plus piping was easier and no heat load in an already hot kitchen. PM was a breeze.
I have often wondered why some of these larger convenience stores don't run small racks for their refrigeration/ac. Could even use heat reclaim to heat in the winters.
I have seen several racks running scrolls and screws (Had one with a back-up screw that was powered by a natural gas V6 engine.) I'm not fond of a screw simply because I am not to familiar with them. I know the basics of how they operate and how they vary the capacity (I cannot remember when they call that..). The newer scrolls are somewhat quieter than some of the first racks I have seen. Seems compressor changes are a bit easier. But it is all in what the customer wants. Some people just don't like change.
I have seen several racks running scrolls and screws (Had one with a back-up screw that was powered by a natural gas V6 engine.) I'm not fond of a screw simply because I am not to familiar with them. I know the basics of how they operate and how they vary the capacity (I cannot remember when they call that..). The newer scrolls are somewhat quieter than some of the first racks I have seen. Seems compressor changes are a bit easier. But it is all in what the customer wants. Some people just don't like change.
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