"kornball" spake:
> "Timothy Daniels" wrote:
>
>>Here are more examples of and advice regarding
>>turbulence and forced draft cooling:
>>
>> http://www.overclockers.com/tips90/ -
>>
>> "Turbulent air cools better. Say, for sake of argument,
>> you have a simple tube with a fan in the middle. The fan pulls
>> air from one side of the tube, and blows into the other. If you
>> have a hot component on the exhaust side of the fan, it will
>> be more efficiently cooled than on the intake side.
>
>
> Say for example, that you have a computer system, not a
> dissimilar situation, and instead of having a reduced flow
> rate from the component no matter which side it's on, you
> have a higher flow rate until you try to test your idea.
That's not English, kornball. Try a course in expository
writing. But if you want to elaborate, be my guest.
Your English is always good for a laugh.
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
"kornball" wrote:
>"Timothy Daniels" wrote:
>> Cool air that contacts the components per
>> unit time is what is important.
>
> Yes, as I've said all along.
>
>> Whether the turbulence that
>> promotes that is caused by design or by accident is not
>> important to the heated parts.
>
>
> This is where you are wrong. You cannot resolve the fact
> that "by design" necessarily means a reduction in flow rate.
Not at all. The turbulence can be generated by many means.
Many current designs generate turbulence with a fan.
> The goal is to maximize flow rate to the part, and away from
> the part. The turbulence that is by design or accident is
> only useful when occuring ON the surface of the part being
> cooled.
You've mistakenly substitued "occurring" for "impinging".
It matters not at all WHERE the turbulence is GENERATED.
But it does matter that it IMPINGES ON THE PART to be cooled -
directly on the part and enegentically enough to penetrate
and scrub away the part's boundary layer of air.
> A perforated grill over anything hot would help if your theory
> were true, but it does not.
It works on my Dell computer! The hard drive is mounted
vertically with its circuit board right behind the holes stamped
in the front of the metal case. Although it would receive the
same amount of cooled air if mounted 6" to 8" back, it is
put right behind the holes - where the turbulence is greatest.
Furthermore, that placement creates more turbulence in the
downstream air, something to be avoided according to you.
But lo and behold, my hard drive and the rest of the system
runs cool, and it has had no failures in 7 1/2 years. Maybe
Dell designers know something about cooling?
> Once again you try to fixate on only one variable...
Such as you have fixated on "smooth flow"?
Please consider that many others recognize turbulent flow
for its value in cooling:
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
"kornball" wrote:
> "Timothy Daniels" wrote:
> It is known that turbulence ON the hot part helps.
Uhh... you mean "impinging on" the hot part.
That means that it doesn't matter where the
turbulence is generated, certainly not just the
"self-turbulence" that you restrictively conceded
in past "discussions".
> IF we could have increased turbulence, created prior
> to reaching the part such that there was then even more
> turbulence ON the hot part, that too would help.
Finally! An admission that turbulence doesn't have
to be generated AT the surface of the part, but that it
could even be generated upstream and still help to cool
the part. CONGRATULATIONS, kornball!
> The problem is, we cannot get that increased turbulence
> prior to the part without a decrease in airflow.
Let me help you. You mean to say that any turbulence
generated upstream of a part to be cooled must be at
the expense of bulk air flow rate because it takes energy
to generate turbulence, and the energy to generate that
turbulence is at the expense of bulk flow rate.
There are two FALLACIES here:
1) That the bulk air flow rate reduction matters more
than the increase in turbulence, and
2) That all turbulence can only be generated by the
same energy that causes the bulk air flow.
Let's perform a gedanken experiment for 1):
Laminar flow depends on careful placement of the
hot parts. They must be directly in the path of the
flowing air because the nature of laminar flow is
that it does not "spread out" well - it just goes in as
straight a line as it can from entrance to exit. So
it is easy to imagine that a hot part, not placed directly
in the flow, or suffering from deflection of the flow by
another part, would overheat, regardless of the intensity
of the bulk air flow. The introduction of turbulence,
however, would smear and spread the air flow all
around in the case, and some of it would impinge
the hot part, cooling it. But, you would say, "That
turbulence was at the expense of the laminar flow rate!"
But so WHAT? It cooled the part, didn't it?
Furthermore, what proof have you that in the general case,
all increase in cooling by turbulent flow is overcome by
the reduction in cooling by laminar flow?
And furthermore than that, what engineering or scientific
basis do you have in claiming that energy expended to
generate turbulence AT THE PART is any less than the
energy expended to generate turbulence UPSTREAM
of the part?
And even furthermore, there are heatsinks that are
designed such that the air is forced to follow a zig-zag
path between "fingers" so as to increase the turbulence
at fingers immediately downstream. Why not place all
the fingers in rows so that turbulence is minimized?
Doesn't the increased turbulence decrease air flow rate?
Of course it does, but the designers calculated that the
increase in cooling more than compensated for it.
As for 2):
There are other ways to generate turbulence than by
using the translational energy of the flowing air itself
to generate turbulence. You can always just use a
fan that is internal to the case to do that. In fact, that is
exactly what CPU and GPU fans do - they increase
the turbulence - the localized flow, as opposed to
the overall bulk flow - that impinges the hot part's
surface (or extended surface, which is what a heatsink
is). This increase in turbulence is NOT at the expense
of the bulk flow rate, and recent PC designs use the
technique extensively.
> This much we see all around us in existing products.
Refutation of your kornball theory are all around you but
you see it not.
On Fri, 6 Oct 2006 22:33:30 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:
>"kony" wrote:
>> "Timothy Daniels" wrote:
>>> And so what if bulk flow rate reduces but the
>>> increased turbulence compensates?
>>
>> So you now concede that flow rate reduces.
>
>
> Do you actually understand English?
> "And so what if" doesn't concede *anything*.
> It's a hypothetical phrase.
Problem is, EVERYTHING you dream up is only hypothetical,
never tested. We're done Tim, no point to this argument.
On Fri, 6 Oct 2006 22:40:35 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:
>"kornball" ignores evidence:
>> "Timothy Daniels" wrote:
>>> Here are some interesting discussions and comments:
>>
>>
>> You still don't get it Tim, there is a flow rate reduction
>> that does matter.
>
>
> Why, then, do manufacturers of industrial cooling systems
> design turbulence production into their systems?
They don't, unless they care not about noise.
Different scenario, different approach to cooling.
On Fri, 6 Oct 2006 22:56:06 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:
>"kornball" gives up:
>> Unfortunately you continually ignore that heated air also
>> has to be removed from the system...
>
>
> Are you implying that trubulent air is hard to remove
> from the system?
No, rather that it is KNOWN it reduces flow rate.
That means you need more noise to move same amount of air,
but that the increased noise level could INSTEAD more even
more air.
Once again I point out the obvious- that when a system is
overheated, the proven solution is to increase airflow, not
increase turbulence.
There's nothing you can claim that changes this basic and
proven fact.
You will continue to think arguing or posting links somehow
mitigates this plan truth but it does not. Only Tim can't
see direct evidence like everyone else.
"kornball" continues like a running toilet:
>
> Problem is, EVERYTHING you dream up is only hypothetical,
> never tested. We're done Tim, no point to this argument.
You just got through saying:
"I'm done with the thread since you never do anything
but troll and pretend to cover something new that was
already covered multiple times- but never a test."
C'mon, kornball, say it a 3rd time for old times sake -
say you're done. <LOL>
"kornball" wrote:
> "Timothy Daniels" wrote:
>
>>"kornball" ignores evidence:
>>> "Timothy Daniels" wrote:
>>>> Here are some interesting discussions and comments:
>>>
>>>
>>> You still don't get it Tim, there is a flow rate reduction
>>> that does matter.
>>
>>
>> Why, then, do manufacturers of industrial cooling systems
>> design turbulence production into their systems?
>
> They don't, unless they care not about noise.
> Different scenario, different approach to cooling.
Awww, now you're introducing another variable to hide behind -
noise. Turbulence cools the parts, but it makes noise inside the
case. I guess noise bothers the dust balls. Konehead, I didn't know
you were so... so... CARING. <LOL>
"kornball" weaves and dances and brings in noise:
> "Timothy Daniels" wrote:
>
>>"kornball" gives up:
>>> Unfortunately you continually ignore that heated air also
>>> has to be removed from the system...
>>
>>
>> Are you implying that trubulent air is hard to remove
>> from the system?
>
> No, rather that it is KNOWN it reduces flow rate.
> That means you need more noise to move same amount of air,
> but that the increased noise level could INSTEAD more even
> more air.
Always another factor, huh, kornball? Now it's "noise".
What will be next? Bad luck? Will turbulence produce
bad luck? <LOL>
> Once again I point out the obvious- that when a system is
> overheated, the proven solution is to increase airflow, not
> increase turbulence.
MmmmHmmmm. And increased airflow doesn't produce
noise? Tell us about it, kornball.
> There's nothing you can claim that changes this basic and
> proven fact.
Yeah, I can. Well-planned turbulence would obviate the
need for your brute-force "solution".
> You will continue to think arguing or posting links somehow
> mitigates this plan truth but it does not. Only Tim can't
> see direct evidence like everyone else.
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
"kornball" gasped:
> "Timothy Daniels" wrote:
>
>
>> That's not English, kornball.
>
> You're wasting your time Tim.
The reason you can't write English, kornball, is the
same reason you think you're an aerodynamicist
and a thermodynamicist - you think you know everything.
"kornball" tries his best joke:
> "Timothy Daniels" wrote:
>
>> Not at all. The turbulence can be generated by many means.
>> Many current designs generate turbulence with a fan.
>
>
> Still wasting time.
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
"kornball" wrote:
> "Timothy Daniels" wrote:
>
>> Uhh... you mean "impinging on" the hot part.
>
> Trying to restate what I meant is yet again,
> wasting time.
Only kornball knows WTF kornball means.
The rest of us are always forced to guess.
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
On Sat, 7 Oct 2006 19:13:23 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:
>"kornball" continues like a running toilet:
>>
>> Problem is, EVERYTHING you dream up is only hypothetical,
>> never tested. We're done Tim, no point to this argument.
>
>
> You just got through saying:
>
> "I'm done with the thread since you never do anything
> but troll and pretend to cover something new that was
> already covered multiple times- but never a test."
>
> C'mon, kornball, say it a 3rd time for old times sake -
> say you're done. <LOL>
Yes, and I am. I've given you all the help you need to
figure out why you find ATX a problem and where your cooling
idea went wrong.
Each time you posted nonsense, I tried to remind you that
your grand theory needed testing.
I am done Tim, done trying to help you learn the basics.
On Sun, 8 Oct 2006 03:45:27 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:
>"kornball" bleated:
>> I am done Tim, done trying to help you learn the basics.
>
>
> You're done all right. You're completely out of weasel room.
> The basics are part of science, and you flunked science.
All the evidence is against you.
Not dissimilar things which confused you, but real, running
systems... that don't overheat like yours.
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
"To induce turbulence within the fins and improve thermal
transmission between the air and metal, Thermalright have
modified the aluminum fins by adding 'proprietary bent winglets'."
"Simple convection is not as effective (even for the same rate
of flow of air), because of the "laminar" flow of air (where the
air at the surface of the heatsink moves slower than that further
away). This effect can be easily seen on a windy day. If you stay
close to a wall or other large area (lying on the ground works too),
it will be noticed that it is less windy than out in the open. Exactly
the same thing happens with heatsinks (but on a somewhat
reduced scale). Creating turbulence is an excellent way to defeat
this process, but this requires fans, and fans are noisy."
"The heat transfer towards the flowing air that can be achieved
with plain fins is relatively restricted. The laminar air flow that
emerges is not sufficient to carry off the heat. Therefore, attempts
are being made to improve heat transfer (fins to air) by producing
more turbulent flow using an appropriate fin geometry."
"Optimizing cooling efficiency in an LIA is achieved by using
a heatsink-based aluminum reflector, where the material has
a high thermal conductivity and the design maximizes the effects
of surface area and turbulence. Within reason, the more surface
area the better the lamp cooling. Also important is turbulence,
because of the skin effect in cooling. A thin layer of air surrounding
a cooling surface acts as a thermal insulator impeding the effect
of forced air-cooling. This layer needs to be disrupted by turbulent
airflow, which can be created by providing irregular fins and fin
geometries."
"at least some said protrusions affect said streaming of said
fluid so as to enhance the turbulence of said streaming of said
fluid, thereby enhancing convective heat transfer from said
object to said fluid."
"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.
"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."
"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."
"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."
"kornball konehead" wrote:
> It is known that turbulence ON the hot part helps. Nobody
> has argued against this.
YOU did! Starting way back on July 10, 2004, in
alt.comp.hardware.homebuilt you argued:
"Those links were examples of what we've been saying all
along, that turbulence should be created on the surface being,
needing cooled."
You said "CREATED ON THE SURFACE", not impinging on
the surface, not aimed at the surface, not directed to the surface.
That was the start of your "Self-Generated Turbulence" theory,
which was a way then to weasel out of your position that turbulence
was just plain bad. Now you're claiming that you meant all along
that the turbulence must be ON the hot part, not necessarily generated
AT the hot part. What a weasel you are!
*TimDaniels*
IF we could have increased
> turbulence, created prior to reaching the part such that
> there was then even more turbulence ON the hot part, that
> too would help. The problem is, we cannot get that
> increased turbulence prior to the part without a decrease in
> airflow.
On Sun, 8 Oct 2006 11:32:19 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:
>"kornball konehead" wrote:
>> It is known that turbulence ON the hot part helps. Nobody
>> has argued against this.
>
>
> YOU did! Starting way back on July 10, 2004, in
> alt.comp.hardware.homebuilt you argued:
>
> "Those links were examples of what we've been saying all
> along, that turbulence should be created on the surface being,
> needing cooled."
>
> You said "CREATED ON THE SURFACE", not impinging on
> the surface, not aimed at the surface, not directed to the surface.
Yes Tim. jThat is ON the hot part.
The reason you still can't understand cooling is that you
can't resolve these finer details. This is not a dissimilar
situation as you're trying ot imply, it is cooling for an
entire system where there is more than one part, more
downstream of the first part cooled.
> "Al Dykes" wrote:
>
>> You are picking *one* aspect of the many that affectthe cooling parts
>> in a box. You also freely jump between the macro and micro effects.
>> What is optimal in one is occasionally sub-optimal in the other.
>
>
>
> I am picking "*one* aspect* to write about that is often denigrated
> by "experts" as being undesirable.
Kony is correct in that you are mixing micro and macro effects and then
assuming the tradeoffs are the same, but they're not.
> You can read countless
> "modder" sites that advise keeping the air flow "smooth" to cool
> the interior parts of a computer as much as possible.
That is because the primary concern in macro case flow is getting the most
volume of air in and out of the case, and to the parts to be cooled, with
the least wasted energy. Or, put another way, the air has to get there (and
then removed) before it can be used for cooling purposes.
Take an extreme example to illustrate the point, like an air-conditioned
computer center where the air-conditioning is floor ducted around the room
and then up into the individual racks for cooling. Clearly, 'turbulence' in
the floor ducting does nothing to 'improve cooling' but does lower the
overall airflow to the racks, or causes one to employ larger, more
powerful, nosier, more costly, fans to over come the resistance caused by
the useless turbulence.
Similarly, creating extraneous turbulence inside the case simply impedes
airflow.
> I merely
> point out that if a part is to be cooled by a forced flow of fluid past
> and over it (such as by forced draft of air), turbulent fluid flow cools
> the part better than laminar fluid flow.
That is in the immediate vicinity of the cooling surface.
> That it is putting the flow
> past the part to be cooled that is more important than merely
> getting bulk air in and out of the case
They're both important. It's of little use to get air in and out of the
case if it hasn't picked up the heat but it's just as useless to pick up
the heat and then not take it out of the case. And there's your clue for
what does what where and why. You want useful turbulence at the dissipating
surface but a low resistance path getting the air to it and back out.
Re: turbulent flow not bad for cooling 