Difference between chiller HE and STD.

[Jacek]

Could anyone explain to me the difference between chillers made in High Efficiency ans Standard versions? Have HE chillers bigger evaporators? Generally, what does HE mean?
To help you answer I'm showing the data for the Trane air-cooled RTAC 140 chiller (chilled water 12/7 deg. C; ambient temp. 35 deg. C):

RTAC 140 STANDARD :
- Cooling capacity = 493,3 kW
- Power Input = 159,3 kW

RTAC 140 HIGH EFFICIENCY:
- Cooling capacity = 515,1 kW
- Power Input = 151,7 kW

What is the difference?

Thanks in advance for your replies.

Regards.

[Grizzly]

The honest answer is I don't know!
But I would assume it has something to do with the Evap sizing.

As you suggest.

It could be as simple as more tube passes within the evap. (Assuming it's a shell and tube).

Grizzly

[Samarjit Sen]

From the datas provided, it appears that the High Efficiency Unit has more refrigeration capacity and less power input than the Standard one. It may be ( I am guessing ) that a bit oversized Condenser is beng used in the HE model, due to which the condensing temperature is lower and which has enhanced the capacity and reduced the power consumption in the HE model.

It is an interesting question and I would like to know if my guess is right or wrong.

[SteinarN]

3 degres C reduction in condensing temperature gives rughly 5% reduction in power consumtion and roughly 4% increased coling capasity. This is for resiprocating compressor and R22. R407C should give similar results. Screws should also give similar or slightly lower increase in cooling performance. It should give similar result in power consumtion also if it is equipped with variable compression ratio slide.

The standard version has a COP of 3,1 at stated conditions. This is actually a lousy COP. The HE version has a COP of 3,4. This isnt that impressive either.

Copeland scroll and Discus compressors running with R22 acheive COP in the range 3,5 to 4 with evaporation at 3C, 44C condensing and zero subcool which can be obtained at conditions specified in the first post in this thread.

It isnt any problem calculating a SWEP PHE with 3C evaporation and 7/12C water. 9K TD on the condenser isnt any problem either.

The problem is the company paying for the construction of buildings and systems often isnt the same company paying the electric bills to run the equipment. It is cheaper to size up the comp instead of sizing up the heat exchangers. And maybe to many in ours business isnt paying enough attention to the subject of optimisation and energy efficiency.
Thats much of the reason behind all this lousy efficience refrigeration equipment.

I dont want to be to harsh, but it is really frustrating to se all this seemingly quality equipment and realise it, more often than not, have huge improvment potential regarding the energy consumtion.

Do a comparision at identical operation condition of a Maneurop resip and a Discus for a smal chiller. You will be amazed at the percentage difference in power consumtion and COP for those to different compressor series.

Calculation software can be downloaded for free, and gives accurate results.

[Steve Wright]

Jacek

In the USA the main difference is the size of the Cond and the Evap.

I ask one of our sales reps here in the office and he said the main difference was the style, size, and configuation of the chiller barrel.

When compairing specs make sure you compare at the same design conditions they can make a big difference in the screw compressor line.

Steve

[Jacek]

From the datas provided, it appears that the High Efficiency Unit has more refrigeration capacity and less power input than the Standard one. It may be ( I am guessing ) that a bit oversized Condenser is beng used in the HE model, due to which the condensing temperature is lower and which has enhanced the capacity and reduced the power consumption in the HE model.

It is an interesting question and I would like to know if my guess is right or wrong.

Many thanks for your reply! I think you are right with the statement about oversizing a condenser. It means that subcooling is bigger (greater cooling capacity). Oversizing condenser (thus decreasing condensing pressure) allows to decrease compressor input power. That is the explanation of my problem:)

Thanks a lot.

Regards,

Jacek

[Lowrider]

a RTAC 140 HE has 24 inches longer condensors then a standard one and 5 instead of 4 condensorfans on each circuit and thus a larger area and a larger airflow over them. Only 4 kg of refrigirant exta needed per circuit!

[Jacek]

Thanks for the replies. To be precise, I mentioned Trane chillers only as an example (I had a Trane catalogue close at hand). Some manufacturers use STD and HE terminology. Therfore, I asked a question.

Regards from Poland.