Author: "enewton57" <enewton57@...> Time: Thu May 30, 2002 5:47 am PDT Link
Hi All,
Here is an update on my oil temp problems and solutions that may be
of some use for future builders.
The engine is a Lycoming O-320 H2AD mounted in an RV-6A. The oil
cooler was a Niagara 7 row cooler mounted on the firewall with a 3"
scat running to it. My oil temps were acceptable in the winter time
but as summer time came with it's 90 degree temps down here in the
south, I found that the oil cooling was inadequate.
During my trip to Sun N' Fun, I was at gross weight with my father-in-
law (250 lbs.) and myself (240 lbs.) and other stuff on board. The
Florida Temps were in the low 90's and fairly high humidity. On
climb out from Perry-Foley airport, my oil temp reached 245 degrees
Fahrenheit with a cruise climb of 160 mph. Cruise temps at 4500
feet were 230 degrees Fahrenheit.
Here is a list of some things I tried:
1. Installed a "Cool Collar" from JC Whitney on the oil filter and
ran a 1" blast tube to it.
2. Sealed up all baffles better.
3. Increased opening on bottom cowl by 30 square inches.
4. Sealed up the gaps around the oil cooler/scat tube adapter.
The above lowered the temps by 10 degrees but still inadequate. So
my next tactic was to relocate the oil cooler from the firewall to
the back of the baffle. I made the opening at the back of the baffle
exactly fit the opening in the oil cooler so there would be no
obstruction at all.
Results - Climb at gross weight on a 90 degree day was still 230
degrees and cruise was 210 degrees.
Better but still too hot for me, so I next replaced the 7 row Niagara
cooler with a 9 row Aero-Classics oil cooler from Pacific Oil Cooler
Service for $205. plus shipping.
Results - 90 degree day, gross weight climb to 8,000 at 130 mph = 210
degrees, cruise at 75% power at 8,000 ft = 185 degrees.
The above is based on my personal experience and your results may
differ. Also note the engine was just overhauled about 40 hours ago
and has just gotten broken in. The oil consumption has now
stabilized. Th cylinder head temps stay at around 375f for climb and
325f for cruise all the time.
Hope this helps someone else,
Regards,
Eric Newton - Long Beach, MS
RV-6A - N57ME (Flying and ready for Waco this weekend (if the
weather is good))
www.ericsrv6a.com
Author: L Farris <jaws48@...> Time: Fri May 31, 2002 7:23 pm PDT Link
Eric,
Did you take any photos of installation? If so, would
you share? I've purcahsed same cooler but haven't
installed it yet.
Thanks.
Larry Farris
--- enewton57 <enewton57@y...> wrote:
> Hi All,
> Here is an update on my oil temp problems and
> solutions that may be
> of some use for future builders.
>
> The engine is a Lycoming O-320 H2AD mounted in an
> RV-6A. The oil
> cooler was a Niagara 7 row cooler mounted on the
> firewall with a 3"
> scat running to it. My oil temps were acceptable in
> the winter time
> but as summer time came with it's 90 degree temps
> down here in the
> south, I found that the oil cooling was inadequate.
> During my trip to Sun N' Fun, I was at gross weight
> with my father-in-
> law (250 lbs.) and myself (240 lbs.) and other stuff
> on board. The
> Florida Temps were in the low 90's and fairly high
> humidity. On
> climb out from Perry-Foley airport, my oil temp
> reached 245 degrees
> Fahrenheit with a cruise climb of 160 mph. Cruise
> temps at 4500
> feet were 230 degrees Fahrenheit.
>
> Here is a list of some things I tried:
>
> 1. Installed a "Cool Collar" from JC Whitney on the
> oil filter and
> ran a 1" blast tube to it.
> 2. Sealed up all baffles better.
> 3. Increased opening on bottom cowl by 30 square
> inches.
> 4. Sealed up the gaps around the oil cooler/scat
> tube adapter.
>
> The above lowered the temps by 10 degrees but still
> inadequate. So
> my next tactic was to relocate the oil cooler from
> the firewall to
> the back of the baffle. I made the opening at the
> back of the baffle
> exactly fit the opening in the oil cooler so there
> would be no
> obstruction at all.
>
> Results - Climb at gross weight on a 90 degree day
> was still 230
> degrees and cruise was 210 degrees.
>
> Better but still too hot for me, so I next replaced
> the 7 row Niagara
> cooler with a 9 row Aero-Classics oil cooler from
> Pacific Oil Cooler
> Service for $205. plus shipping.
>
> Results - 90 degree day, gross weight climb to 8,000
> at 130 mph = 210
> degrees, cruise at 75% power at 8,000 ft = 185
> degrees.
>
> The above is based on my personal experience and
> your results may
> differ. Also note the engine was just overhauled
> about 40 hours ago
> and has just gotten broken in. The oil consumption
> has now
> stabilized. Th cylinder head temps stay at around
> 375f for climb and
> 325f for cruise all the time.
>
> Hope this helps someone else,
>
> Regards,
>
> Eric Newton - Long Beach, MS
> RV-6A - N57ME (Flying and ready for Waco this
> weekend (if the
> weather is good))
> www.ericsrv6a.com
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Author: "enewton57" <enewton57@...> Time: Sun Jun 2, 2002 1:22 pm PDT Link
There a couple of pics on my website at:
www.ericsrv6a.com
Go to the firewall forward (page 1) and see the addendum.
However, I must say, the way I mounted will probably not work for the
majority of Lycomings. I have the O-320 H2AD and was able to mount
it behind cylinder number 3. Most Lycomings have the oil dip stick
there and an oil cooler wouldn't fit. My engine has the oil dip
stick near the center of the engine so the area behind Number 3
cylinder was wide open. Unless you happen to have the H2AD engine,
you will probably need to mount it behind cylinder number 4.
Regards,
Eric Newton - Long Beach, Ms
RV-6A - N57ME (just back from the fly-in in Waco)
www.ericsrv6a.com
--- In vansairforce@y..., L Farris <jaws48@y...> wrote:
> Eric,
> Did you take any photos of installation? If so, would
> you share? I've purcahsed same cooler but haven't
> installed it yet.
> Thanks.
> Larry Farris
> --- enewton57 <enewton57@y...> wrote:
> > Hi All,
> > Here is an update on my oil temp problems and
> > solutions that may be
> > of some use for future builders.
> >
> > The engine is a Lycoming O-320 H2AD mounted in an
> > RV-6A. The oil
> > cooler was a Niagara 7 row cooler mounted on the
> > firewall with a 3"
> > scat running to it. My oil temps were acceptable in
> > the winter time
> > but as summer time came with it's 90 degree temps
> > down here in the
> > south, I found that the oil cooling was inadequate.
> > During my trip to Sun N' Fun, I was at gross weight
> > with my father-in-
> > law (250 lbs.) and myself (240 lbs.) and other stuff
> > on board. The
> > Florida Temps were in the low 90's and fairly high
> > humidity. On
> > climb out from Perry-Foley airport, my oil temp
> > reached 245 degrees
> > Fahrenheit with a cruise climb of 160 mph. Cruise
> > temps at 4500
> > feet were 230 degrees Fahrenheit.
> >
> > Here is a list of some things I tried:
> >
> > 1. Installed a "Cool Collar" from JC Whitney on the
> > oil filter and
> > ran a 1" blast tube to it.
> > 2. Sealed up all baffles better.
> > 3. Increased opening on bottom cowl by 30 square
> > inches.
> > 4. Sealed up the gaps around the oil cooler/scat
> > tube adapter.
> >
> > The above lowered the temps by 10 degrees but still
> > inadequate. So
> > my next tactic was to relocate the oil cooler from
> > the firewall to
> > the back of the baffle. I made the opening at the
> > back of the baffle
> > exactly fit the opening in the oil cooler so there
> > would be no
> > obstruction at all.
> >
> > Results - Climb at gross weight on a 90 degree day
> > was still 230
> > degrees and cruise was 210 degrees.
> >
> > Better but still too hot for me, so I next replaced
> > the 7 row Niagara
> > cooler with a 9 row Aero-Classics oil cooler from
> > Pacific Oil Cooler
> > Service for $205. plus shipping.
> >
> > Results - 90 degree day, gross weight climb to 8,000
> > at 130 mph = 210
> > degrees, cruise at 75% power at 8,000 ft = 185
> > degrees.
> >
> > The above is based on my personal experience and
> > your results may
> > differ. Also note the engine was just overhauled
> > about 40 hours ago
> > and has just gotten broken in. The oil consumption
> > has now
> > stabilized. Th cylinder head temps stay at around
> > 375f for climb and
> > 325f for cruise all the time.
> >
> > Hope this helps someone else,
> >
> > Regards,
> >
> > Eric Newton - Long Beach, MS
> > RV-6A - N57ME (Flying and ready for Waco this
> > weekend (if the
> > weather is good))
> > www.ericsrv6a.com
> __________________________________________________
> Do You Yahoo!?
> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.com
Author: L Farris <jaws48@...> Time: Mon Jun 3, 2002 5:26 am PDT Link
Eric,
Thanks. Looks similar to installation I have in
progress on opposite side of engine.
Larry
--- enewton57 <enewton57@y...> wrote:
> There a couple of pics on my website at:
>
> www.ericsrv6a.com
>
> Go to the firewall forward (page 1) and see the
> addendum.
>
> However, I must say, the way I mounted will probably
> not work for the
> majority of Lycomings. I have the O-320 H2AD and
> was able to mount
> it behind cylinder number 3. Most Lycomings have
> the oil dip stick
> there and an oil cooler wouldn't fit. My engine has
> the oil dip
> stick near the center of the engine so the area
> behind Number 3
> cylinder was wide open. Unless you happen to have
> the H2AD engine,
> you will probably need to mount it behind cylinder
> number 4.
>
> Regards,
>
> Eric Newton - Long Beach, Ms
> RV-6A - N57ME (just back from the fly-in in Waco)
> www.ericsrv6a.com
>
> --- In vansairforce@y..., L Farris <jaws48@y...>
> wrote:
> > Eric,
> > Did you take any photos of installation? If so,
> would
> > you share? I've purcahsed same cooler but haven't
> > installed it yet.
> > Thanks.
> > Larry Farris
> > --- enewton57 <enewton57@y...> wrote:
> > > Hi All,
> > > Here is an update on my oil temp problems and
> > > solutions that may be
> > > of some use for future builders.
> > >
> > > The engine is a Lycoming O-320 H2AD mounted in
> an
> > > RV-6A. The oil
> > > cooler was a Niagara 7 row cooler mounted on the
> > > firewall with a 3"
> > > scat running to it. My oil temps were
> acceptable in
> > > the winter time
> > > but as summer time came with it's 90 degree
> temps
> > > down here in the
> > > south, I found that the oil cooling was
> inadequate.
> > > During my trip to Sun N' Fun, I was at gross
> weight
> > > with my father-in-
> > > law (250 lbs.) and myself (240 lbs.) and other
> stuff
> > > on board. The
> > > Florida Temps were in the low 90's and fairly
> high
> > > humidity. On
> > > climb out from Perry-Foley airport, my oil temp
> > > reached 245 degrees
> > > Fahrenheit with a cruise climb of 160 mph.
> Cruise
> > > temps at 4500
> > > feet were 230 degrees Fahrenheit.
> > >
> > > Here is a list of some things I tried:
> > >
> > > 1. Installed a "Cool Collar" from JC Whitney on
> the
> > > oil filter and
> > > ran a 1" blast tube to it.
> > > 2. Sealed up all baffles better.
> > > 3. Increased opening on bottom cowl by 30
> square
> > > inches.
> > > 4. Sealed up the gaps around the oil
> cooler/scat
> > > tube adapter.
> > >
> > > The above lowered the temps by 10 degrees but
> still
> > > inadequate. So
> > > my next tactic was to relocate the oil cooler
> from
> > > the firewall to
> > > the back of the baffle. I made the opening at
> the
> > > back of the baffle
> > > exactly fit the opening in the oil cooler so
> there
> > > would be no
> > > obstruction at all.
> > >
> > > Results - Climb at gross weight on a 90 degree
> day
> > > was still 230
> > > degrees and cruise was 210 degrees.
> > >
> > > Better but still too hot for me, so I next
> replaced
> > > the 7 row Niagara
> > > cooler with a 9 row Aero-Classics oil cooler
> from
> > > Pacific Oil Cooler
> > > Service for $205. plus shipping.
> > >
> > > Results - 90 degree day, gross weight climb to
> 8,000
> > > at 130 mph = 210
> > > degrees, cruise at 75% power at 8,000 ft = 185
> > > degrees.
> > >
> > > The above is based on my personal experience and
> > > your results may
> > > differ. Also note the engine was just
> overhauled
> > > about 40 hours ago
> > > and has just gotten broken in. The oil
> consumption
> > > has now
> > > stabilized. Th cylinder head temps stay at
> around
> > > 375f for climb and
> > > 325f for cruise all the time.
> > >
> > > Hope this helps someone else,
> > >
> > > Regards,
> > >
> > > Eric Newton - Long Beach, MS
> > > RV-6A - N57ME (Flying and ready for Waco this
> > > weekend (if the
> > > weather is good))
> > > www.ericsrv6a.com
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! - Official partner of 2002 FIFA World Cup
> > http://fifaworldcup.yahoo.com
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Author: "davidawilks" <davidawilks@...> Time: Tue Jun 4, 2002 5:47 pm PDT Link
Has anyone tried using a dedicated exhaust duct from the back side
of the oil cooler to an external vent grafted to the engine
cowling? This would create a massive draw of airflow through the
cooler and positively reduce oil temps. The amount of airflow
through the cowl openings is so great without having adequate
exhaust opening to create a proper steady airflow through the cooler
specifically. This creates a stagnant pressure and uneven cooling.
Of course this is just opinion, but I would certainly believe a
change would make huge gains in cooling efficiency.
David Wilks
http://www.davidawilks.com
Evergreen Helicopters International
FBO/GLS
Author: Mark Harrison <rv7dreamer@...> Time: Tue Jun 4, 2002 7:25 pm PDT Link
You would need a damper valve to control the air flow.
If the air is too fast it will not provide efficient
cooling.
--- davidawilks <davidawilks@y...> wrote:
> Has anyone tried using a dedicated exhaust duct from
> the back side
> of the oil cooler to an external vent grafted to the
> engine
> cowling? This would create a massive draw of
> airflow through the
> cooler and positively reduce oil temps. The amount
> of airflow
> through the cowl openings is so great without having
> adequate
> exhaust opening to create a proper steady airflow
> through the cooler
> specifically. This creates a stagnant pressure and
> uneven cooling.
>
> Of course this is just opinion, but I would
> certainly believe a
> change would make huge gains in cooling efficiency.
>
> David Wilks
> http://www.davidawilks.com
>
> Evergreen Helicopters International
> FBO/GLS
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Author: "William Slaughter" <willslau@...> Time: Wed Jun 5, 2002 5:29 am PDT Link
For any given air-to-liquid heat exchanger and air temperature combination,
the three most important factors affecting performance are usually
considered to be airflow, airflow and airflow. The mechanism involved on the
air side of the cooler is identical to that involved in producing those
pesky wind chill factors in the winter. The faster the wind blows, the
colder it seems, due to more and more heat being lost to the air stream.
Another thing to remember is that all oil coolers are not created equal. I
spent a fair amount of time at the Pacific Oil Cooler booth at OSH last
year. They sell and service the Positech, the Niagara and the Stewart
Warner, and they indicate that for any given form factor the Stewart Warner
cools the most and the Positech the least, with the Niagara in the middle.
They would undoubtedly be able to offer good advice on this issue.
William Slaughter
-----Original Message-----
From: Mark Harrison [mailto:rv7dreamer@y...]
Sent: Tuesday, June 04, 2002 9:21 PM
To: vansairforce@yahoogroups.com
Subject: Re: [VAF Mailing List] Re: High Oil Temps
You would need a damper valve to control the air flow.
If the air is too fast it will not provide efficient
cooling.
--- davidawilks <davidawilks@y...> wrote:
> Has anyone tried using a dedicated exhaust duct from
> the back side
> of the oil cooler to an external vent grafted to the
> engine
> cowling? This would create a massive draw of
> airflow through the
> cooler and positively reduce oil temps. The amount
> of airflow
> through the cowl openings is so great without having
> adequate
> exhaust opening to create a proper steady airflow
> through the cooler
> specifically. This creates a stagnant pressure and
> uneven cooling.
>
> Of course this is just opinion, but I would
> certainly believe a
> change would make huge gains in cooling efficiency.
>
> David Wilks
> http://www.davidawilks.com
>
> Evergreen Helicopters International
> FBO/GLS
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Online help on this group at:
http://help.yahoo.com/help/groups/
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Author: "Randy Lervold" <randy@...> Time: Wed Jun 5, 2002 8:05 am PDT Link
William, my experience reinforces this exactly. I swapped out a Niagara for a Stewart Warner with no other changes and DID notice a reduction in temperature. If curious see the "Oil cooler" section on this page...
http://www.rv-8.com/FirewallForward.htm
Randy Lervold
RV-8, 164.8 hrs
They sell and service the Positech, the Niagara and the Stewart
Warner, and they indicate that for any given form factor the Stewart Warner
cools the most and the Positech the least, with the Niagara in the middle.
They would undoubtedly be able to offer good advice on this issue.
William Slaughter
-----Original Message-----
From: Mark Harrison [mailto:rv7dreamer@y...]
Sent: Tuesday, June 04, 2002 9:21 PM
To: vansairforce@yahoogroups.com
Subject: Re: [VAF Mailing List] Re: High Oil Temps
You would need a damper valve to control the air flow.
If the air is too fast it will not provide efficient
cooling.
--- davidawilks <davidawilks@y...> wrote:
> Has anyone tried using a dedicated exhaust duct from
> the back side
> of the oil cooler to an external vent grafted to the
> engine
> cowling? This would create a massive draw of
> airflow through the
> cooler and positively reduce oil temps. The amount
> of airflow
> through the cowl openings is so great without having
> adequate
> exhaust opening to create a proper steady airflow
> through the cooler
> specifically. This creates a stagnant pressure and
> uneven cooling.
>
> Of course this is just opinion, but I would
> certainly believe a
> change would make huge gains in cooling efficiency.
>
> David Wilks
> http://www.davidawilks.com
>
> Evergreen Helicopters International
> FBO/GLS
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Online help on this group at:
http://help.yahoo.com/help/groups/
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Online help on this group at:
http://help.yahoo.com/help/groups/
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Author: Mark Harrison <rv7dreamer@...> Time: Wed Jun 5, 2002 11:13 am PDT Link
Yes airflow is an important factor but only up to the
capacity of the cooler. The rate of heat transfer is
calculated using the change in temperature across the
heat exchanger. You can actually increase the mass
flow of air through the cooler enough so that the air
temp on either side will be the same. i.e. not have
removed any heat from the cooler. So my point is if
the air is too fast it will not provide adequate
cooling.
--- William Slaughter <willslau@a...>
wrote:
> For any given air-to-liquid heat exchanger and air
> temperature combination,
> the three most important factors affecting
> performance are usually
> considered to be airflow, airflow and airflow. The
> mechanism involved on the
> air side of the cooler is identical to that involved
> in producing those
> pesky wind chill factors in the winter. The faster
> the wind blows, the
> colder it seems, due to more and more heat being
> lost to the air stream.
> Another thing to remember is that all oil coolers
> are not created equal. I
> spent a fair amount of time at the Pacific Oil
> Cooler booth at OSH last
> year. They sell and service the Positech, the
> Niagara and the Stewart
> Warner, and they indicate that for any given form
> factor the Stewart Warner
> cools the most and the Positech the least, with the
> Niagara in the middle.
> They would undoubtedly be able to offer good advice
> on this issue.
>
> William Slaughter
>
> -----Original Message-----
> From: Mark Harrison [mailto:rv7dreamer@y...]
> Sent: Tuesday, June 04, 2002 9:21 PM
> To: vansairforce@yahoogroups.com
> Subject: Re: [VAF Mailing List] Re: High Oil Temps
> You would need a damper valve to control the air
> flow.
> If the air is too fast it will not provide
> efficient
> cooling.
> --- davidawilks <davidawilks@y...> wrote:
> > Has anyone tried using a dedicated exhaust duct
> from
> > the back side
> > of the oil cooler to an external vent grafted to
> the
> > engine
> > cowling? This would create a massive draw of
> > airflow through the
> > cooler and positively reduce oil temps. The
> amount
> > of airflow
> > through the cowl openings is so great without
> having
> > adequate
> > exhaust opening to create a proper steady
> airflow
> > through the cooler
> > specifically. This creates a stagnant pressure
> and
> > uneven cooling.
> >
> > Of course this is just opinion, but I would
> > certainly believe a
> > change would make huge gains in cooling
> efficiency.
> >
> > David Wilks
> > http://www.davidawilks.com
> >
> > Evergreen Helicopters International
> > FBO/GLS
> __________________________________________________
> Do You Yahoo!?
> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.com
> Online help on this group at:
> http://help.yahoo.com/help/groups/
> Your use of Yahoo! Groups is subject to the Yahoo!
> Terms of Service.
> [Non-text portions of this message have been
> removed]
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Author: Roger Embree <rembree@...> Time: Wed Jun 5, 2002 12:13 pm PDT Link
Mark Harrison wrote:
> Yes airflow is an important factor but only up to the
> capacity of the cooler. The rate of heat transfer is
> calculated using the change in temperature across the
> heat exchanger. You can actually increase the mass
> flow of air through the cooler enough so that the air
> temp on either side will be the same. i.e. not have
> removed any heat from the cooler. So my point is if
> the air is too fast it will not provide adequate
> cooling.
Sorry but this is not correct.
Heat added or removed from a system is
weight x specific gravity x change in temp.
There are two sides to a heat exchanger but the heat in one side is equal to
the heat out of the other, so,
weight (of air) x specific gravity (of air) x temp change (of air) =
weight (of oil) x specific gravity (of oil) x temp change (of oil)
if you pump lots and lots of air through the exchanger, the inlet and outlet
temps do not have to vary much to remove the same BTU's. Twice the volume of
air - half the temp change of air, Four times the volume of air - one quarter
the temp change of air etc.
Roger Embree
Author: "William Slaughter" <willslau@...> Time: Wed Jun 5, 2002 1:44 pm PDT Link
Anybody out there actually working in the heat exchanger business want to
jump in on this?
-----Original Message-----
From: Mark Harrison [mailto:rv7dreamer@y...]
Sent: Wednesday, June 05, 2002 10:33 AM
To: vansairforce@yahoogroups.com
Subject: RE: [VAF Mailing List] Re: High Oil Temps
Yes airflow is an important factor but only up to the
capacity of the cooler. The rate of heat transfer is
calculated using the change in temperature across the
heat exchanger. You can actually increase the mass
flow of air through the cooler enough so that the air
temp on either side will be the same. i.e. not have
removed any heat from the cooler. So my point is if
the air is too fast it will not provide adequate
cooling.
--- William Slaughter <willslau@a...>
wrote:
> For any given air-to-liquid heat exchanger and air
> temperature combination,
> the three most important factors affecting
> performance are usually
> considered to be airflow, airflow and airflow. The
> mechanism involved on the
> air side of the cooler is identical to that involved
> in producing those
> pesky wind chill factors in the winter. The faster
> the wind blows, the
> colder it seems, due to more and more heat being
> lost to the air stream.
> Another thing to remember is that all oil coolers
> are not created equal. I
> spent a fair amount of time at the Pacific Oil
> Cooler booth at OSH last
> year. They sell and service the Positech, the
> Niagara and the Stewart
> Warner, and they indicate that for any given form
> factor the Stewart Warner
> cools the most and the Positech the least, with the
> Niagara in the middle.
> They would undoubtedly be able to offer good advice
> on this issue.
>
> William Slaughter
>
> -----Original Message-----
> From: Mark Harrison [mailto:rv7dreamer@y...]
> Sent: Tuesday, June 04, 2002 9:21 PM
> To: vansairforce@yahoogroups.com
> Subject: Re: [VAF Mailing List] Re: High Oil Temps
> You would need a damper valve to control the air
> flow.
> If the air is too fast it will not provide
> efficient
> cooling.
> --- davidawilks <davidawilks@y...> wrote:
> > Has anyone tried using a dedicated exhaust duct
> from
> > the back side
> > of the oil cooler to an external vent grafted to
> the
> > engine
> > cowling? This would create a massive draw of
> > airflow through the
> > cooler and positively reduce oil temps. The
> amount
> > of airflow
> > through the cowl openings is so great without
> having
> > adequate
> > exhaust opening to create a proper steady
> airflow
> > through the cooler
> > specifically. This creates a stagnant pressure
> and
> > uneven cooling.
> >
> > Of course this is just opinion, but I would
> > certainly believe a
> > change would make huge gains in cooling
> efficiency.
> >
> > David Wilks
> > http://www.davidawilks.com
> >
> > Evergreen Helicopters International
> > FBO/GLS
> __________________________________________________
> Do You Yahoo!?
> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.com
> Online help on this group at:
> http://help.yahoo.com/help/groups/
> Your use of Yahoo! Groups is subject to the Yahoo!
> Terms of Service.
> [Non-text portions of this message have been
> removed]
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Online help on this group at:
http://help.yahoo.com/help/groups/
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Author: "William Slaughter" <willslau@...> Time: Wed Jun 5, 2002 1:44 pm PDT Link
Oops, should have read all the emails in the hopper. Thanks Roger, for a
succinct technical write up of this process.
William Slaughter
-----Original Message-----
From: Roger Embree [mailto:rembree@s...]
Sent: Wednesday, June 05, 2002 1:36 PM
To: vansairforce@yahoogroups.com
Subject: Re: [VAF Mailing List] Re: High Oil Temps
Mark Harrison wrote:
> Yes airflow is an important factor but only up to the
> capacity of the cooler. The rate of heat transfer is
> calculated using the change in temperature across the
> heat exchanger. You can actually increase the mass
> flow of air through the cooler enough so that the air
> temp on either side will be the same. i.e. not have
> removed any heat from the cooler. So my point is if
> the air is too fast it will not provide adequate
> cooling.
Sorry but this is not correct.
Heat added or removed from a system is
weight x specific gravity x change in temp.
There are two sides to a heat exchanger but the heat in one side is equal
to
the heat out of the other, so,
weight (of air) x specific gravity (of air) x temp change (of air) =
weight (of oil) x specific gravity (of oil) x temp change (of oil)
if you pump lots and lots of air through the exchanger, the inlet and
outlet
temps do not have to vary much to remove the same BTU's. Twice the volume
of
air - half the temp change of air, Four times the volume of air - one
quarter
the temp change of air etc.
Roger Embree
Online help on this group at:
http://help.yahoo.com/help/groups/
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Author: Mark Harrison <rv7dreamer@...> Time: Wed Jun 5, 2002 4:19 pm PDT Link
Here is my reasoning behind what I say. The actual
equation for heat transfer is Q=mc(Th-Tc). Q is the
rate of heat transfer, m mass flow rate of the fluid,
c specific heat capacity of the fluid, Th temp hot
side and Tc temp cold side. The longer a fluid is in
contact with a surface the more heat will be
transfered. The faster the air the less time it is in
contact with the cooler. Therefor the change in temp
across the will drop and then the heat trransfer rate
will drop. Granted in our application we may never
see speeds fast enough to reach this point. I have a
lot of experience with heat exchangers and their
therory of operation from 8 years in the nuclear power
industry. If you really want to increase cooling
increase the surface area of cooler. Just my two
cents!
--- William Slaughter <willslau@a...>
wrote:
> Oops, should have read all the emails in the hopper.
> Thanks Roger, for a
> succinct technical write up of this process.
>
> William Slaughter
> -----Original Message-----
> From: Roger Embree [mailto:rembree@s...]
> Sent: Wednesday, June 05, 2002 1:36 PM
> To: vansairforce@yahoogroups.com
> Subject: Re: [VAF Mailing List] Re: High Oil Temps
> Mark Harrison wrote:
>
> > Yes airflow is an important factor but only up
> to the
> > capacity of the cooler. The rate of heat
> transfer is
> > calculated using the change in temperature
> across the
> > heat exchanger. You can actually increase the
> mass
> > flow of air through the cooler enough so that
> the air
> > temp on either side will be the same. i.e. not
> have
> > removed any heat from the cooler. So my point
> is if
> > the air is too fast it will not provide adequate
> > cooling.
>
> Sorry but this is not correct.
>
> Heat added or removed from a system is
> weight x specific gravity x change in temp.
>
> There are two sides to a heat exchanger but the
> heat in one side is equal
> to
> the heat out of the other, so,
>
> weight (of air) x specific gravity (of air) x temp
> change (of air) =
> weight (of oil) x specific gravity (of oil) x
> temp change (of oil)
>
> if you pump lots and lots of air through the
> exchanger, the inlet and
> outlet
> temps do not have to vary much to remove the same
> BTU's. Twice the volume
> of
> air - half the temp change of air, Four times the
> volume of air - one
> quarter
> the temp change of air etc.
>
> Roger Embree
> Online help on this group at:
> http://help.yahoo.com/help/groups/
> Your use of Yahoo! Groups is subject to the Yahoo!
> Terms of Service.
> [Non-text portions of this message have been
> removed]
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com
Author: Herb Feldman <az944@...> Time: Wed Jun 5, 2002 7:51 pm PDT Link
I guess next winter when the outside air temp is 0 deg f, I'll feel a
lot warmer outside if the wind speed is 35 knots than I would if the
wind was calm. I can hardly wait for hurricane wind speeds, I probably
could stay outside in my bathing suit. ; )
Herb
Mark Harrison wrote:
> Here is my reasoning behind what I say. The actual
> equation for heat transfer is Q=mc(Th-Tc). Q is the
> rate of heat transfer, m mass flow rate of the fluid,
> c specific heat capacity of the fluid, Th temp hot
> side and Tc temp cold side. The longer a fluid is in
> contact with a surface the more heat will be
> transfered. The faster the air the less time it is in
> contact with the cooler. Therefor the change in temp
> across the will drop and then the heat trransfer rate
> will drop. Granted in our application we may never
> see speeds fast enough to reach this point. I have a
> lot of experience with heat exchangers and their
> therory of operation from 8 years in the nuclear power
> industry. If you really want to increase cooling
> increase the surface area of cooler. Just my two
> cents!
> --- William Slaughter <willslau@a...>
> wrote:
> > Oops, should have read all the emails in the hopper.
> > Thanks Roger, for a
> > succinct technical write up of this process.
> >
> > William Slaughter
> > -----Original Message-----
> > From: Roger Embree [mailto:rembree@s...]
> > Sent: Wednesday, June 05, 2002 1:36 PM
> > To: vansairforce@yahoogroups.com
> > Subject: Re: [VAF Mailing List] Re: High Oil Temps
> > Mark Harrison wrote:
> >
> > > Yes airflow is an important factor but only up
> > to the
> > > capacity of the cooler. The rate of heat
> > transfer is
> > > calculated using the change in temperature
> > across the
> > > heat exchanger. You can actually increase the
> > mass
> > > flow of air through the cooler enough so that
> > the air
> > > temp on either side will be the same. i.e. not
> > have
> > > removed any heat from the cooler. So my point
> > is if
> > > the air is too fast it will not provide adequate
> > > cooling.
> >
> > Sorry but this is not correct.
> >
> > Heat added or removed from a system is
> > weight x specific gravity x change in temp.
> >
> > There are two sides to a heat exchanger but the
> > heat in one side is equal
> > to
> > the heat out of the other, so,
> >
> > weight (of air) x specific gravity (of air) x temp
> > change (of air) =
> > weight (of oil) x specific gravity (of oil) x
> > temp change (of oil)
> >
> > if you pump lots and lots of air through the
> > exchanger, the inlet and
> > outlet
> > temps do not have to vary much to remove the same
> > BTU's. Twice the volume
> > of
> > air - half the temp change of air, Four times the
> > volume of air - one
> > quarter
> > the temp change of air etc.
> >
> > Roger Embree
> > Online help on this group at:
> > http://help.yahoo.com/help/groups/
> > Your use of Yahoo! Groups is subject to the Yahoo!
> > Terms of Service.
> > [Non-text portions of this message have been
> > removed]
> __________________________________________________
> Do You Yahoo!?
> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.com
> Online help on this group at:
> http://help.yahoo.com/help/groups/
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Author: "alex_roup" <alex_roup@...> Time: Thu Jun 6, 2002 8:29 am PDT Link
Ok here's my stab at it-
Let's define these variables:
Qdot - rate of heat exchange (want to be as high as possible)
mdot - mass flow rate through the cooler
Cp - specific heat of air
Ta - Temperature of the incoming air
Tc - Temperature of the cooler
rho - air density
V - air velocity
A - cooler cross-sectional area
Cd - drag coefficient of the cooler
D - drag of the cooler (want to be as low as possible)
Pf - static pressure in front of the cooler
Pr - static pressure behind the cooler
Let's assume that rho, Ta, Tc, Cp, Cd, and Pr are constant. As you
said, we have:
Qdot = mdot Cp (Tc - Ta) (1)
We also can write
mdot = rho V A (2)
and
D = Cd 1/2 rho V^2 A (3)
Combining (1) and (2) gives us
Qdot = V A rho Cp (Tc - Ta) (4)
from which we can conclude that higher velocity and higher area both
increase the heat transfer rate. But we want to minimize drag as
well. Let Qdot0 be the required heat transfer rate. Rewrite (4) in
terms of Qdot0 and solve for A as:
A = Qdot0 / [V rho Cp (Tc - Ta)] (5)
and substitute into (3) to get
D = V Cd 1/2 Qdot0 / [Cp (Tc - Ta)] (6)
It follows from (6) that to minimize drag at a *specific* cooling
rate we should minimize the velocity through the cooler. It follows
from (5) that, for a constant heat transfer rate Qdot, minimizing V
means maximizing A.
Well, how do we minimize the velocity of the air through the cooler?
We can write
D = (Pi - Po) A (7)
Combining (7) with (3) and solving for V gives
V = sqrt[(Pf - Pr)/(Cd 1/2 rho)] (8)
Therefore, reducing the static pressure in front of the cooler
reduces the velocity through it. The best way to do that is to
create a separate plenum for the cooler.
So my conclusions are:
- higher velocity through a particular installation increases cooling
- to design a system to minimize drag while maintaining the required
cooling rate we should
* maximize cross-sectional area
* reduce velocity (to the minimum required for sufficient
cooling) by decreasing the upstream pressure through the
use of a separate plenum
For what it's worth...
-Alex
--- In vansairforce@y..., Mark Harrison <rv7dreamer@y...> wrote:
> Here is my reasoning behind what I say. The actual
> equation for heat transfer is Q=mc(Th-Tc). Q is the
> rate of heat transfer, m mass flow rate of the fluid,
> c specific heat capacity of the fluid, Th temp hot
> side and Tc temp cold side. The longer a fluid is in
> contact with a surface the more heat will be
> transfered. The faster the air the less time it is in
> contact with the cooler. Therefor the change in temp
> across the will drop and then the heat trransfer rate
> will drop.
Author: "alex_roup" <alex_roup@...> Time: Thu Jun 6, 2002 8:57 am PDT Link
Oops, equation (7) should read
D = (Pf - Pr) A (7)
in case anyone read that far.
-Alex
--- In vansairforce@y..., "alex_roup" <alex_roup@y...> wrote:
> Ok here's my stab at it-
>
> Let's define these variables:
>
> Qdot - rate of heat exchange (want to be as high as possible)
> mdot - mass flow rate through the cooler
> Cp - specific heat of air
> Ta - Temperature of the incoming air
> Tc - Temperature of the cooler
> rho - air density
> V - air velocity
> A - cooler cross-sectional area
> Cd - drag coefficient of the cooler
> D - drag of the cooler (want to be as low as possible)
> Pf - static pressure in front of the cooler
> Pr - static pressure behind the cooler
>
> Let's assume that rho, Ta, Tc, Cp, Cd, and Pr are constant. As you
> said, we have:
>
> Qdot = mdot Cp (Tc - Ta) (1)
>
> We also can write
>
> mdot = rho V A (2)
>
> and
>
> D = Cd 1/2 rho V^2 A (3)
>
> Combining (1) and (2) gives us
>
> Qdot = V A rho Cp (Tc - Ta) (4)
>
> from which we can conclude that higher velocity and higher area
both
> increase the heat transfer rate. But we want to minimize drag as
> well. Let Qdot0 be the required heat transfer rate. Rewrite (4)
in
> terms of Qdot0 and solve for A as:
>
> A = Qdot0 / [V rho Cp (Tc - Ta)] (5)
>
> and substitute into (3) to get
>
> D = V Cd 1/2 Qdot0 / [Cp (Tc - Ta)] (6)
>
> It follows from (6) that to minimize drag at a *specific* cooling
> rate we should minimize the velocity through the cooler. It
follows
> from (5) that, for a constant heat transfer rate Qdot, minimizing V
> means maximizing A.
>
> Well, how do we minimize the velocity of the air through the
cooler?
> We can write
>
> D = (Pi - Po) A (7)
>
> Combining (7) with (3) and solving for V gives
>
> V = sqrt[(Pf - Pr)/(Cd 1/2 rho)] (8)
>
> Therefore, reducing the static pressure in front of the cooler
> reduces the velocity through it. The best way to do that is to
> create a separate plenum for the cooler.
>
> So my conclusions are:
>
> - higher velocity through a particular installation increases
cooling
> - to design a system to minimize drag while maintaining the
required
> cooling rate we should
> * maximize cross-sectional area
> * reduce velocity (to the minimum required for sufficient
> cooling) by decreasing the upstream pressure through the
> use of a separate plenum
>
> For what it's worth...
>
> -Alex
> --- In vansairforce@y..., Mark Harrison <rv7dreamer@y...> wrote:
> > Here is my reasoning behind what I say. The actual
> > equation for heat transfer is Q=mc(Th-Tc). Q is the
> > rate of heat transfer, m mass flow rate of the fluid,
> > c specific heat capacity of the fluid, Th temp hot
> > side and Tc temp cold side. The longer a fluid is in
> > contact with a surface the more heat will be
> > transfered. The faster the air the less time it is in
> > contact with the cooler. Therefor the change in temp
> > across the will drop and then the heat trransfer rate
> > will drop.
Author: Mark Harrison <rv7dreamer@...> Time: Thu Jun 6, 2002 3:17 pm PDT Link
>From an EXPERT. I was wrong.
Your theory follows the right thought path, but you
have an incorrect assumption. You assume that it is
possible to flow the air fast enough such that the air
will not increase in temperature. The only way this
could occur is if the 2nd law of Thermodynamics is
violated because you would have a perfectly reversible
process. This would imply that the heat exchanger is
a perfect insulator, in which case you would have no
heat exchanger at all, and no heat transfer would take
place at any airflow.
Having stated this, what does happen is that as the
temperature difference approaches zero, the rate at
which heat transfer is increasing with airflow
approaches zero. In other words, if you plotted a
curve of heat transfer vs airflow, the curve would
begin with a steep slope, then almost flatten out as
the airflow increases. Another way of thinking about
it is that in the heat transfer equation you
referenced, the increase in mass flow more than
compensates for the decrease in temperature
difference, even as the temperature difference gets
very small.
Best regards,
__________________________________________________
Glenn Sollie
Tech Center Manager
ThermaSys Heat Transfer
2776 Gunter Park Drive, E., Suite R-S
Montgomery, AL 36109
voice: (334) 244-9240 x105
fax: (334) 244-9248
--- alex_roup <alex_roup@y...> wrote:
> Oops, equation (7) should read
>
> D = (Pf - Pr) A (7)
>
> in case anyone read that far.
>
> -Alex
> --- In vansairforce@y..., "alex_roup"
> <alex_roup@y...> wrote:
> > Ok here's my stab at it-
> >
> > Let's define these variables:
> >
> > Qdot - rate of heat exchange (want to be as high
> as possible)
> > mdot - mass flow rate through the cooler
> > Cp - specific heat of air
> > Ta - Temperature of the incoming air
> > Tc - Temperature of the cooler
> > rho - air density
> > V - air velocity
> > A - cooler cross-sectional area
> > Cd - drag coefficient of the cooler
> > D - drag of the cooler (want to be as low as
> possible)
> > Pf - static pressure in front of the cooler
> > Pr - static pressure behind the cooler
> >
> > Let's assume that rho, Ta, Tc, Cp, Cd, and Pr are
> constant. As you
> > said, we have:
> >
> > Qdot = mdot Cp (Tc - Ta) (1)
> >
> > We also can write
> >
> > mdot = rho V A (2)
> >
> > and
> >
> > D = Cd 1/2 rho V^2 A (3)
> >
> > Combining (1) and (2) gives us
> >
> > Qdot = V A rho Cp (Tc - Ta) (4)
> >
> > from which we can conclude that higher velocity
> and higher area
> both
> > increase the heat transfer rate. But we want to
> minimize drag as
> > well. Let Qdot0 be the required heat transfer
> rate. Rewrite (4)
> in
> > terms of Qdot0 and solve for A as:
> >
> > A = Qdot0 / [V rho Cp (Tc - Ta)] (5)
> >
> > and substitute into (3) to get
> >
> > D = V Cd 1/2 Qdot0 / [Cp (Tc - Ta)] (6)
> >
> > It follows from (6) that to minimize drag at a
> *specific* cooling
> > rate we should minimize the velocity through the
> cooler. It
> follows
> > from (5) that, for a constant heat transfer rate
> Qdot, minimizing V
> > means maximizing A.
> >
> > Well, how do we minimize the velocity of the air
> through the
> cooler?
> > We can write
> >
> > D = (Pi - Po) A (7)
> >
> > Combining (7) with (3) and solving for V gives
> >
> > V = sqrt[(Pf - Pr)/(Cd 1/2 rho)] (8)
> >
> > Therefore, reducing the static pressure in front
> of the cooler
> > reduces the velocity through it. The best way to
> do that is to
> > create a separate plenum for the cooler.
> >
> > So my conclusions are:
> >
> > - higher velocity through a particular
> installation increases
> cooling
> > - to design a system to minimize drag while
> maintaining the
> required
> > cooling rate we should
> > * maximize cross-sectional area
> > * reduce velocity (to the minimum required for
> sufficient
> > cooling) by decreasing the upstream pressure
> through the
> > use of a separate plenum
> >
> > For what it's worth...
> >
> > -Alex
> > --- In vansairforce@y..., Mark Harrison
> <rv7dreamer@y...> wrote:
> > > Here is my reasoning behind what I say. The
> actual
> > > equation for heat transfer is Q=mc(Th-Tc). Q is
> the
> > > rate of heat transfer, m mass flow rate of the
> fluid,
> > > c specific heat capacity of the fluid, Th temp
> hot
> > > side and Tc temp cold side. The longer a fluid
> is in
> > > contact with a surface the more heat will be
> > > transfered. The faster the air the less time it
> is in
> > > contact with the cooler. Therefor the change in
> temp
> > > across the will drop and then the heat trransfer
> rate
> > > will drop.
__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com