[AusNOG] Data Suburb

Thu Jan 5 16:27:39 EST 2012

I think I should refrain from starting ausnog PUE wars in future ;-p.

I visited Hoverdam during November 2010, visually the water supply looks
pretty low. hopefully the DC has reliable source of water that won't be hit
by the water shortages the water authority have predicted to happen in the
next 3 years in las vegas area.  Looks like these guys have multiple
cooling systems anyway (perhaps contributes to the higher "Projected" PUE
of 1.24) so they might be able to switch between evaporative cooling to
something less efficient.

2012/1/5 Bevan Slattery <Bevan.Slattery at nextdc.com>

>  Sorry - please note that the reason the COP is higher on B at lower
> temps is because unit "B" it has the capability of going free air
> (compressorless) and operate like a car radiator (love car analogies in
> data centres ;)).  Note that in cold conditions the COP is much, much
> higher at 100% capacity than at lower levels which would contradict Tony's
> previous statement.  So like I said before, it's complex story subject to
> over-simplification.
>
>
>
> Cheers
>
>
>
> [b]
>
>
>
> *From:* ausnog-bounces at lists.ausnog.net [mailto:
> ausnog-bounces at lists.ausnog.net] *On Behalf Of *Bevan Slattery
> *Sent:* Thursday, 5 January 2012 11:42 AM
> *To:* Tony de Francesco; 'Luke Smith'
>
> *Cc:* ausnog at ausnog.net
> *Subject:* Re: [AusNOG] Data Suburb
>
>
>
> Tony,
>
>
>
> *Coefficient of Performance @ Specified Load & Ambient Temperature*
>
> Capacity
>
> *10%*
>
> *25%*
>
> *50%*
>
> *75%*
>
> *100%*
>
>
>
>
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
>
>
>
>
> *A*
>
> *B*
>
> *A*
>
> *B*
>
> *A*
>
> *B*
>
> *A*
>
> *B*
>
> *A*
>
> *B*
>
>
>
>
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> * *
>
> Ambient Temperature °C
>
> 0
>
>
>
>
>
>
>
> 6.18
>
>
>
>
>
>
>
> 14.67
>
>
>
>
>
>
>
> 25.96
>
>
>
>
>
>
>
> 33.98
>
>
>
>
>
>
>
> 39.71
>
> 5
>
>
>
>
>
>
>
> 6.18
>
>
>
>
>
>
>
> 13.08
>
>
>
>
>
>
>
> 19.85
>
>
>
>
>
>
>
> 16.33
>
>
>
>
>
>
>
> 18.24
>
> 10
>
>
>
>
>
>
>
> 3.78
>
>
>
>
>
>
>
> 5.53
>
>
>
>
>
>
>
> 8.88
>
>
>
>
>
>
>
> 10.55
>
>
>
>
>
>
>
> 12.98
>
> 15
>
>
>
> 3.09
>
> 7.25
>
> 4.56
>
> 7.46
>
> 6.25
>
> 6.81
>
> 6.75
>
> 6.39
>
> 7.18
>
> 20
>
>
>
> 2.13
>
> 6.17
>
> 4.02
>
> 6.06
>
> 5.82
>
> 5.68
>
> 6.33
>
> 5.77
>
> 5.97
>
> 25
>
>
>
> 2.00
>
> 5.18
>
> 3.84
>
> 5.17
>
> 5.19
>
> 5.00
>
> 5.44
>
> 4.99
>
> 5.11
>
> 30
>
>
>
> 1.84
>
> 4.67
>
> 3.44
>
> 4.33
>
> 4.50
>
> 4.40
>
> 4.92
>
> 4.19
>
> 4.35
>
> 35
>
>
>
> 1.70
>
> 3.72
>
> 3.52
>
> 3.77
>
> 4.79
>
> 3.73
>
> 4.6
>
> 3.60
>
> 4.09
>
>
>
> I think it's more appropriate to provide a fuller picture than 1 example.
> Here's two (2) aircooled chillers (water coolant) and their COP's at
> different levels.
>
>
> It's not accurate to depict that they day "N" installation is that the
> units are at 100%.  Obviously, you know that's not true for various
> reasons.  Firstly, if you have an N+1 system then depending on the number
> of units you have you will be operating.  In fact at 100% in some
> facilities will have N+2 or even N+3 for efficiency, reliability and
> sometime acoustical reasons.  Units have variable speed drives, multiple
> staged compressors which make running at lower levels as efficient as
> operating at day "N".  However, no one in a serious DC space (that I know
> of) ever expects to run outdoor cooling plant at 100% load.  The sweet spot
> depending on the ambient conditions in between 20-75% capacity.  But this
> is capacity of a chiller, not utilisation of the DC floor.  Outdoor mech is
> a game of swings and roundabouts at each "stage jump" which get smoothed
> out more and more as the facility gets bigger (assuming it's common
> infrastructure).
>
>
>
> Cheers
>
>
>
> [b]
>
>
>
>
>
>
>
> *From:* ausnog-bounces at lists.ausnog.net
> [mailto:ausnog-bounces at lists.ausnog.net] *On Behalf Of *Tony de Francesco
> *Sent:* Thursday, 5 January 2012 10:48 AM
> *To:* 'Luke Smith'
> *Cc:* ausnog at ausnog.net
> *Subject:* Re: [AusNOG] Data Suburb
>
>
>
> Thanks very much for that analogy as it precisely highlights one of the
> reasons why the "reduced efficiency at part load" argument gets so much
> traction with people, i.e. people think they understand the technology and
> find over simplified examples to justify their position.
>
>
>
> If you will allow me, let me educate on how an air conditioning system
> (and not a V8 engine) responds to part load operation:
>
>
>
> Let's look at an air conditioning unit that is designed for 1000kW of
> cooling, but is delivering only 200kW of cooling:
>
>
>
> a)     Firstly when operating at a full 1000kWs of Load:
>
> a.     Refrigeration System Power Use:           EER of 3.5, equating to
> around 286kW of absorbed power
>
> b.    Air handling System Power Use:            (relates to 69,000m³/s of
> supply air based on an equipment ΔT of 12°C) equating to around 60kW of fan
> power
>
> TOTAL = 346kW of power use or a pPUE of 1.346
>
>
>
> b)    The same system at 200kW of Load:
>
> a.     Refrigeration System Power Use:           EER of 8 (as the
> refrigeration COP improves at part load), equating to around 25kW of
> absorbed power
>
> b.    Air handling System Power Use:            (relates to 14,000m³/s of
> supply air based on an equipment ΔT of 12°C) equating to around 1kW of fan
> power (as per the fan laws).
>
> TOTAL = 26kW of power use or a pPUE of 1.130
>
>
>
> So you can see in this example at 20% load utilisation, the pPUE (i.e.
> cooling system PUE) should be around 1.130 and increase to 1.346 as the
> load approaches 100%.
>
>
>
> This correlation is often not the case with electrical systems, such as
> static UPS and DRUPS units, which tend to have lower efficiency at part
> load and better efficiency at full load (as per your V8 analogy).
>
>
>
> However, the improvement in the cooling system PUE at part load generally
> offsets the reduction in electrical system PUE at part load and so the
> overall facility PUE remains static over the load utilisation range.
>
>
>
> Hope this helps your understanding although please feel free to email me
> on or off list if you would like me to explain any of this in further
> detail.
>
>
>
>
>
>
>
> Kind Regards
>
>
>
> Tony de Francesco
> Technical Director
>
> email: tonyd at pue.com.au
>
> mob: +61 (0) 457 701 179
>
> .....................................................
>
>
>   ------------------------------
>
> *From:* ausnog-bounces at lists.ausnog.net
> [mailto:ausnog-bounces at lists.ausnog.net] *On Behalf Of *Luke Smith
> *Sent:* Thursday, 5 January 2012 11:16 AM
> *To:* ausnog at ausnog.net
> *Subject:* Re: [AusNOG] Data Suburb
>
>
>
> >  This statement has permeated the industry and led to people accepting
> lower levels of efficiency at part load in the hope that their PUE will
> improve as the load increases.  There is no technical reason why PUE has to
> suffer at part utilization, other than people accepting a facility design
> that allows this.
>
> Applying an analogy... if this were the case then you should also expect
> the same economy from a 6.0l V8 as you get from a 2.0l four in the same
> car. But the world doesn't work like that.
>
>
>
> Unless its *very* modular and you can totally turn off the bits you are
> not using then you simply can't expect a half used facility to have the
> same efficiency as a fully utilised one half the size. Going back to the
> analogy modern V8s have cylinder deactivation that saves some of the
> overhead, but they still waste energy spinning a few extra cranks and
> pistons about that they don't need 99% of the time.
>
> --
> Cheers,
>
> Luke Smith
> 0419 671 006
>
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