Post Reply 
 
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Engine Cooling Fans
04-10-2017, 20:05 (This post was last modified: 04-10-2017 20:11 by davidbrady.)
Post: #1
Engine Cooling Fans
Speaking with my mechanic at Burke Christian Tours I understand that in 2018 Prevost is transitioning to electric cooling fans. I think he said they were using eight small diameter fans in an array using brushless motors. I'm picturing continuously variable speed drives and a separate engine driven alternator for power. It'll be interesting to see how they work out the power requirements. It'd be great if this system can be retrofitted to our buses.
Find all posts by this user
Like Post Quote this message in a reply
04-10-2017, 21:36
Post: #2
RE: Engine Cooling Fans
İmage
(04-10-2017 20:05)davidbrady Wrote:  Speaking with my mechanic at Burke Christian Tours I understand that in 2018 Prevost is transitioning to electric cooling fans. I think he said they were using eight small diameter fans in an array using brushless motors. I'm picturing continuously variable speed drives and a separate engine driven alternator for power. It'll be interesting to see how they work out the power requirements. It'd be great if this system can be retrofitted to our buses.

I see this set up a lot here in Florida , mostly on local transit buses.
Mostly MAN diesels. Like the set up here.

William Jensen
2001 Liberty Non slide XLII
Deerfield Beach, Florida
Find all posts by this user
Like Post Quote this message in a reply
04-11-2017, 10:50 (This post was last modified: 04-11-2017 15:53 by davidbrady.)
Post: #3
Big Grin RE: Engine Cooling Fans
That's neat William. From what I can tell, the advantages of this setup are packaging and granularity of control. I don't see any improvement as far as efficiency. it's hard to beat a belt driven system. In a brushless fan set up we have alternator losses, variable frequency drive losses and brushless motor losses. The typical 40HP engine load is probably still around that number. 30kW at 24V is 1250A, and at 48V is 625A, for a per fan supply of 80A. Fan power is directly proportional to pressure and flow, and input power varies with the cube of fan speed. Maybe because the fans are close to the radiator they can be spun slower, maybe because the radiator has greater effective fan area the motors can be spun slower, all this contributes to less input power and less amperage.

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
Find all posts by this user
Like Post Quote this message in a reply
04-13-2017, 14:53
Post: #4
RE: Engine Cooling Fans
My '03 chassis year H3 uses three AX v-belts. At the rpm we're spinning the AX is good fo 20HP. That's 60HP total for three belts. This affirms the notion that the mechanical fan requires in the neighborhood if 40HP from the S60.

Ernie, does the XL use three v-belts or two?

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
Find all posts by this user
Like Post Quote this message in a reply
04-14-2017, 10:59 (This post was last modified: 04-14-2017 16:54 by davidbrady.)
Post: #5
RE: Engine Cooling Fans
Here's an interesting page which shows that:
http://www.engineeringtoolbox.com/fan-af...d_196.html

1) Fan flow rate is proportional to the cube of diameter,
2) Pressure is proportional to the square of diameter, and
3) Power is proportional to the fifth power of diameter.

So, moving to multiple 16" fans and retaining the same flow and pressure of one 32" fan we need 32 fans. Eight in parallel to get the flow and four in series to get the pressure. Of course each fan consumes 1/32 of the power of the 32" fan.

The challenge Prevost has is to select individual fans that operate optimally along their volume / pressure curves; that is, the fans in the array can all be different. This way, they may be able to reduce the number of fans used and the power required.

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
Find all posts by this user
Like Post Quote this message in a reply
Post Reply 




User(s) browsing this thread: 1 Guest(s)