Energy Management of Chiller

Hi guys,

Currently i'm maintaining several type and brand of chillers at the sites and i was thinking to do an energy management of centralized chiller plant.
One of my proposal is to regulate outgoing/supply chilled water temperature setting to the optimum set point which means the highest supply chilled water can goes with not affecting thermal comfort at the rooms. I've done to Trane chiller and the result is good.
But the question here, is there any side impact/effect to the chiller efficiency if the supply chilled water is set from design 44degF to 48degF (the 4degF increase is the maximum it can goes - not to compromise the comfort level)

thanx

Hi schiZ0prEni

the first thing to consider is power analasyse & power factor correction maybe an option

Systems that are not power optimised waste a lot of electricity

I have just emailed you an attachment with all the details

R's chillerman

Your email account has been shut down

what is your new email & I will resend you the document

R's chillerman

If you raise the chilled water temp, depending on the building system you could use more power on the fans as with VAVs will tend to open up and call for more motor speed. You may save power on EDHs by minimising over cooling zones. There is only one way to know and that is accurate measurement of power, ambient and a bunch of other things and working on a holistic approach. Saving power is best done with a team effort so try to get the client and tenants involved. Keep us updated on the results.

Dude, sorry for the late reply. I was away for the last 2 weeks.
u can email me at schiZ0prEni@yahoo.com

tq

Quote:

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Originally Posted by schiZ0prEni

Dude, sorry for the late reply. I was away for the last 2 weeks.
u can email me at schiZ0prEni@yahoo.com

tq

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Hi tq

seems to have sent ok this time

R's chillerman

Tq for the reply Tesla.

the main purpose of the project is to SAVE ENERGY (Electricity) and the biggest electricity consumer in a common building is Chiller Plant system or chiller itself. Hence, it is more practical and effective way to concentrate on chiller site. Furthermore, the ACMV system that i'm working on doesn't has VAV and the blowers/fans at AHUs are all installed without VSD wich means no matter how high the Supply Chilled Water temperature to the AHUs, it will stay running at the same speed.

i've completed the testing (raise the Supply Chilled Water Temperature) for a month, and the result of energy saving has been shown on the electricity bill.

Rule of thumb: 1degC increase in Supply Chilled Water temperature reduces the Compressor power consumption by 10% - 15%.

i've achieved my target to Save Energy, but i'm yet to convince myself whether the action of raising the temperature setpoint will affect chiller performance/efficiency or lifespan.

Dude,

Indeed PF correction can save energy but not much. Furthermore, the current system is running with PF=0.98, which is good enough.

i'm looking at the solution which can give high impact (reduction of energy) to the electricity bill as a whole.
Chiller Plant system's Efficiency will be my next project.

tq

Hi schiz,
There are lots of options, not sure about your location though, locally I have a lot of savings gained by night time full air purge of building using full outside air to effectively cool the structure of high rise buildings, the concrete structure is a heat sink/negative effect.
Buffer tanks for chilled water, for between season periods and short cycling chillers.
Enthalpy controllers for outside air make up.
Power factor correction from 0.98 to 0.99 is a huge saving considering inductive and resistive loadings, finally convinced a major power user to spend money, and was recovered in 3 months, savings were in region of $15000 per quarter payment period. Then I got bagged for not being more convincing, cheeeeez

Hi schiZOprEni
The effects of raising the chilled water set point will increase efficiency of the chiller (COP) and increase the life (reducing wear) of chiller. It will have a slight influence on the occupied space humidity. Ideally the chilled water should be reset with a chilled water reset function so as when high temp ambient the chilled water set point will be at it's lowest and when the ambient is low the chilled water set point is high. The settings and range will depend on the load U value and capacity of chiller. More complex are where there are multiple chillers of different types which can handle different load rages more efficiently. Chilled water set points can be changed but some older chillers will fully load at startup which can waste energy. There is also load shedding where the chilled water set point and building temps are dropped to precool a building before severely limiting the load of chiller when peak tariff happens. The fans speed or static pressure set point can be dropped too.
What control are you using to achieve the savings? are you manually changing the set points on the chillers or whiting to the chillers via BMS?

Tesla,

I agree with u.

I changed the setpoint by manually keyed in the new set point at chiller control panel and monitored by BMS

Magoo,

the building if totally OFF during night time.

Can you share with me the data of energy reduction by changing PF from 0.98 to 0.99?
Chillers and pumps set are definitely inductive load.

Quote:

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Originally Posted by schiZ0prEni

Dude,

Indeed PF correction can save energy but not much. Furthermore, the current system is running with PF=0.98, which is good enough.

i'm looking at the solution which can give high impact (reduction of energy) to the electricity bill as a whole.
Chiller Plant system's Efficiency will be my next project.

tq

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Hi Schiz,

you did not mention a 0.98 pf correction prior to giving new email for pdf, that is good, do the units have pfc built in to each unit... it is a massive saving correcting when pfc is low

R's chillerman

here the Electrical Power Provider will penalized any premises owner if PF is below than 0.85. Nowadays, major mechanical equipments (inductive load) will be installed with a set of capacitor banks next to their electrical board.

Quote:

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Originally Posted by schiZ0prEni

here the Electrical Power Provider will penalized any premises owner if PF is below than 0.85. Nowadays, major mechanical equipments (inductive load) will be installed with a set of capacitor banks next to their electrical board.

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Your ok schiz .. I am familiar with pfc & penalties, thats why I offered you the info that you wanted, then suddenly after recieving, you knew all about it....can only presume my pdf educated you !

R's chillerman

message for Chillerman2006, Magoo and Tesla:

Have you guys done anything similar project as mine? project which is to conserve energy by doing some engineering solution to the chiller plant system.

maybe u guys could share information with me/others.

Quote:

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Originally Posted by schiZ0prEni

message for Chillerman2006, Magoo and Tesla:

Have you guys done anything similar project as mine? project which is to conserve energy by doing some engineering solution to the chiller plant system.

maybe u guys could share information with me/others.

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Hi tq

looking back through all the posts, I think the info is all there for you mate,

all three have looked at savings for you from different angles, But can not tell you exact savings as per each post, savings vary per application,

You will need to carry out your own trial & error or employ a specialist to assess your energy consumption, which will result in a detailed break down of where energy can be saved ..... going over what the mixed posts are

Increasing set point (note tesla's things to check first)
pfc (note Magoo's knowledge that 0.01 increase can have substantial savings)
free cooling (note magoo's suggestion of useing abient air for night cooling/make sure mechanical cooling comes on & takes control of the building before sun up)
pfc (again, look into having the whole buildings supply corrected, not just chillers)
another option if not already in place, is radient heat repelling film for the windows, especially if you have many in constant sunlight

If still stuck maybe contact Tesla/Magoo direct & see if they can fit your company into their busy schedules, for a visit & assess your building for you...as its not something that can be done over the phone, for starters you need power analisyse carried out

R's chillerman