sphenix-magnet-l AT lists.bnl.gov
Subject: sPHENIX discussion of the superconducting solenoid
List archive
[Sphenix-magnet-l] FW: power consumption estimation in water-cooled-bus ... and delta-T
- From: "Yip, Kin" <kinyip AT bnl.gov>
- To: "sphenix-magnet-l AT lists.bnl.gov" <sphenix-magnet-l AT lists.bnl.gov>
- Subject: [Sphenix-magnet-l] FW: power consumption estimation in water-cooled-bus ... and delta-T
- Date: Wed, 30 Sep 2020 21:53:07 +0000
|
Hi,
Roberto has just sent me his revised calculation for the delta-T (between bus and water flow) and the delta-T is reduced to 3.58 K (or C).
His main point is that it’s a “small” no. (not 30 K or C) I attach Roberto’s calculation below for future reference.
Kin
From: Than, Yatming (Roberto) <ythan AT bnl.gov>
Had some errors. R.
From: sPHENIX-magnet-l <sphenix-magnet-l-bounces AT lists.bnl.gov> on behalf of Yip, Kin <kinyip AT bnl.gov>
Hi,
Not quite right. Like what I said in my last email, +ve side would have 2 WCB’s in parallel and -ve side would have 2 WCB’s in parallel, so each carry half of the 4600 A.
So, for the 2 WCB’s, the total length is 268.66 ft, but it carries 2300 A, not 4600 A !!!
[ I think Dave assumed 200 ft and would arrive at 7.2 kW for each sign. ] Total WCB’s (4 of them) => 4.83*2 ~ 9.66 kW .
Kin
From: Streckenbach, Brian <bstreckenbach AT bnl.gov>
I measured the bus out, and used the cad model for what isn’t there. I have two section of bus, from:
See below, the bus is the red pipe with white jumper boxes
The lengths I measured for the main bus run and the platform bus run are as follows: Main bus : 1275 +- 90 inches (106.25 +- 7.5 ft) (1008B to IR deck) Platform bus: 337 +- 10 inches (28.08 +- .8) (deck to platform)
I added the deviation because some bus are longer than others, so it’s a rough average. (with a slight error) So that’s 134.33 ft of just copper bus, per run So double that is about 269, multiply by the 3.4 µΩ / ft is now 0.0009134 4600 amps, is 19.33 kW? (9.66 kW per side) I think this math works out.
From: Yip, Kin <kinyip AT bnl.gov>
Hi,
This is a follow-up to the previous email and I change the subject to represent the subject a bit better.
(1)
While chatting with Carl, he made me remember that the nature of using 2 WCB’s (sharing 4600 A) per sign (+/-) made the above estimation a factor of 2 wrong.
So, if I use the above assumption of 100 ft, each WCB is 0.00034 Ohm but each has only 4600/2 ~ 2300 A
Nevertheless, 100 ft is probably an underestimate of the total WCB length; but it should be <200 ft (last time Brian estimated when we bought cables). Brian is going to measure it again. If we use 200 ft, resistance is 6.8E-4 Ohm (for each WCB), total power = 7.194 kW again 😊
{ I guess Dave probably just used the 200 ft. }
Roberto Than talked to me about the temperature gradient in the WCB (between the inner diameter of the bus and the water flow). He made an estimation of the delta-T which I enclose below.
***************************************************** Roberto ****************************************************** Water flow Water temperature and Heat transfer gradient between water and water cooled bus sets the final operating temperature of the power bus. The final operating temperature sets the electrical resistance of bus, and thus the final Joule losses power dissipation. Not too bad as expected.
**************************************************************************************************************************************************
Kin
From: sPHENIX-magnet-l <sphenix-magnet-l-bounces AT lists.bnl.gov>
On Behalf Of Yip, Kin
Hi, Bob Lambiase gave me some ideas ... Modifying those ideas a bit, I plug in some nos. and apply them to various Ohm's laws:
(1) Water-cooled-bus ... Say, let's call the resistance 3.4 µΩ / ft. (near the higher end of Dave's range). R(100 ft) => 0.00034 Ohm ( for each sign) Power = I^2 * R where I ~ 4600 A ~ 7.194 kW ... close to Dave's 7.2 kW (each). { We probably shouldn't count the distance in the air between 1008B and 1008 ...as mother nature takes of those ?!}
(2) Say, our total resistance is like BaBar's ~1.25E-3 Ohm. Static Voltage across the dump resistor: V = 4600 A * 1.25E-3 Ohm ~ 5.75 V [ When it quenches, it's much larger .. but quench only last 38 sec < a minute ...]
Power in dump resistor (0.068 Ohm) ~ V^2/0.068 ~ 486 W close to Dave's 0.5 kW.
(3) Power Supply, this one we have to check with Pablo. There are 2 SCR's ? If each one is 1 V, total power (for two) = 2*1V*4600A ~ 9.2 kW, just a bit bigger than Dave's 8 kW.
I wrote this Kin On 9/29/20 3:57 PM, Streckenbach, Brian wrote:
|
Attachment:
sPHENIXwatercooledbis.mcdx
Description: sPHENIXwatercooledbis.mcdx
- [Sphenix-magnet-l] FW: power consumption estimation in water-cooled-bus ... and delta-T, Yip, Kin, 09/30/2020
Archive powered by MHonArc 2.6.24.