Heat Pipe Modeling and Design II

 

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Welcome, thanks for joining ACT for a webinar on heat pipe design and modeling!

 

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So today we’re going to be talking about exactly that, modeling and designing with heat pipes and this is actually a question we get very frequently from customers through our website and people are just very interested in I think, heat pipes can potentially solve my problem.

 

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How do I kind of take it to the next step and figure out on my own, whether or not it’s going to solve my problem? So today we’re going to go through some fairly basic steps just to give a first-order approximation on whether heat pipes will work for you and from there we would always recommend contacting ACT and we can help you take it the next steps and create from concept

to final product what a heat pipe solution might look like.

 

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For just a quick background on Advanced Cooling Technologies, we were founded in 2003, currently, we have over 220 employees and over 200, 000 square feet. We have two office locations, one in Lancaster Pennsylvania and one in York Pennsylvania.  Throughout our history, our core values have been innovation teamwork and customer care. We like to work very closely with our customers and partners on very detailed and challenging solutions with heat pipes and other thermal technologies to really solve some of the most challenging problems in the industry.

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That does require a lot of those three core values innovation, teamwork and customer care. Just some awards that we’ve been given over the past several year’s product innovation awards the 2020 military and aerospace product of the year which was pump two phase-related and then the AHR green building award.

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Which was a heat pipe or thermosyphon-based solution for energy recovery applications. So, jumping into the content here, the objectives of today’s webinar are basically to provide an understanding of heat pipe operation so give you kind of some background on the heat pipe theory and how it’s going to work in your system and then really just dive into some of the design guidelines so provide you with kind of those tools so you have them in your toolbox where you can design and properly ask if a heat pipe will work in my given application. So from there we’ll jump into quickly the theory.

 

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Heat pipes, some of the advantages and then get into some of the examples on designing them.

 

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Very quickly, I know a lot of you joining are probably familiar with heat pipes. We’ll give kind of a basic understanding of a heat pipe and what it is a passive two-phase operating closed-loop

system. So how you utilize a heat pipe is anywhere where you may have conduction limitations in your system so you can’t spread the heat out significantly enough to meet your temperature

requirements or if you want to transfer heat from point to point so moving heat from an isolated source or electronics component to a heat sink that might be downstream from your devices.

 

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In those two operations, a heat pipe has a very nice way to achieve that goal and the way it works is at the heat input area or known in the heat pipe as an evaporator you are boiling the fluid

 

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so the heat goes in and you’re vaporizing at that interface creating a vapor that creates a pressure gradient within the heat pipe itself and that pressure gradient forces the fluid all the way to wherever it’s colder in your system so in the example you see here in the top it’s pushing that heat from left to right and going into the condenser zone which is where it will give up its latent heat condensed back into a liquid and will be captured within the wick structure so the wick structure in a heat pipe lines the inside diameter and it captures that fluid at the condenser and then it creates a passive capillary force that pumps that fluid passively back from the condenser to the evaporator. So at the end of the day you have no moving parts.

 

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A very highly reliable system because it doesn’t have any real failure mechanisms as long as you kind of operate within your boundary conditions. You get very efficient heat transfer so because of the latent heat of vaporization, you have very high heat transfer coefficients at both those interfaces and you are able to achieve a very low-temperature gradient typically between like two and five degree temperature difference across end to end of the heat pipe.

 

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The benefits for for heat pipes in many cases the benefit is size weight power and flexibility so in the in the size and weight. A lot of times the alternative option for a heat pipe solution is just simply adding more heat sink volume so creating a more massive heat sink will give you some thermal performance benefits but will also eventually hit a limitation as you can’t spread the heat anymore so it does have the ability to make a more compact heat sink.

 

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Because of the better heat spreading and then the larger benefit is typically the power

 

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so in many cases, you can with the same size heat sink increase the amount of power you can output or you can increase the power and create more heat sink volume by better spreading and

better heat transport in your system and the flexibility at the end of the day is primarily what our customers come back to us for because heat pipes can be bent and routed into a lot of different geometries, it is a very flexible technology for in instances where you might be retrofitting it into an existing design that just increased the power capabilities from

 

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one design to the next. It does have the ability to integrate into a lot of different geometries and one of the biggest questions we get very early on in customers looking at heat pipes for the first time is the reliability and the this is a very real question but it’s one that is typically mitigated fairly early on because a lot of times the boundary conditions.

 

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Power requirements will dictate whether or not a heat pipe’s fit and if you can operate within

 

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those operating conditions that are suitable for heat pipes, it should be a very long life

 

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operating device. So once you properly design it into your system if you’re maintaining the

 

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temperature and power limits within a heat pipe it should be a very long life design. These

 

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type of systems have been integrated into very harsh environment type applications

 

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defense aerospace medical applications things that have very stringent requirements and have

 

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kind of that of that need for very long life and very highly reliable systems

 

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and the final question is kind of “when do we use heat pipes and what are the thermal

 

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performance expectations with heat pipes?” and that’s where we’ll get into a lot of the design

 

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and modeling work but as I mentioned earlier, the two primary areas where you would look to

 

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improve thermal performance with heat pipes is heat spreading which

 

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is the example you’re seeing here so you can see in the plate to the left you have three hot spots, really two in the top and one on the bottom where you’re not able to spread the

 

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heat out as quickly as you would want to to keep those electronics operating safely. So in

 

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this example those blue lines that you see on both sides of the plate are liquid cold rails and

 

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the objective here would just be to conduct the heat out to those cold rails and maintain

 

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a safe operating temperature at your electronics. So while the aluminum plate wasn’t able to do it

 

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with the thermal conductivity of aluminum by integrating heat pipes in there you can

 

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see you’re able to kind of short circuit that path out to the liquid cold rail so in the in

 

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the bottom case it was just a matter of putting enough heat pipes in there to move the full power

 

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and in the top case um it was actually a very short thermal pass so it wasn’t a very long path

 

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to conduct but in this case you had such a high heat flux that you were still getting hot spots

 

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there so in this case we we routed the heat pipes in such a way that you created a long condenser

 

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area along the cold rail and that was really able to drive down those temperatures as well

 

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and just looking at some product examples you can see several here and there are many more on

 

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our website to give you some ideas of how heat pipes are used but again here we want to kind of

 

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show the flexibility in terms of applications these have been integrated into a lot of very

 

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complex systems and also the geometric flexibility you can see heat pipes of different configurations

 

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there bent routed some with many heat input zones so it doesn’t have to be heat input at one end and

 

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condensing at the other end you can have multiple evaporator sections to pick up heat from multiple

 

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electronics and you could also condense to to multiple areas as well the heat pipe because

 

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it’s operating in passive two-phase principles it will find an equilibrium as long as you’re

 

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not exceeding one of your your power limitations so again just kind of a nice demonstration of some

 

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of the flexibility you can see in some of these designs and that’s where again act could really

 

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help out if if you bring us a problem we can give you kind of a quick order of magnitude stance on

 

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yes this can be solved with a heat pipe or or maybe it’s not a great fit based on

 

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the power the boundary conditions and some of the geometric limitations

 

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so now we’ll dive into designing with the heat pipes and that’s that’s really kind of the the

 

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basis of this webinar so we’ll talk about the power capacity which is one of the major

 

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hurdles in designing with with heat pipes and then we’ll also talk about the

 

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design guidelines and get into some modeling later on

 

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so the power capabilities um there’s a lot of of published data on heat pipe limits and it’s it’s

 

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one of the um first things you need to consider when when designing with heat pipes and there’s

 

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there’s really several limits that’s kind of bound the the power capacity of heat pipes um

 

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in many of the terrestrial applications the real defining one is going to be the capillary limit

 

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the capillary limit is is basically the wick’s ability to pump the fluid back from

 

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the condenser to the evaporator and so it has to overcome all the pressure drops in the system

 

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one of the largest pressure drops would be the gravity head if it needs to pump against gravity

 

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which in most applications where it’s going into things that may be variable orientation or may

 

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have to operate in in different configurations it’s a requirement you have to operate in in

 

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any type of orientation so you need to overcome that gravity head when you do face with it the

 

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other option if you do have flexibility on your orientation and you can orient the condenser above

 

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the the evaporator you can move significantly amounts of heat in those type of applications

 

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so those operate mainly on the entrainment limit which is the ability for the the vapor to kind of

 

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push up against the liquid shear strength sheer force that’s coming down an ability to overcome

 

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that and so in those type of applications you can move a significant amount of heat but for

 

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the purpose of this today’s webinar we’re going to focus mainly on the capillary limit

 

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and that’s usually the driving factors in in terrestrial type designs

 

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so the limits here are a function of several different items but primarily the ones listed

 

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here are what we’re going to focus on because they can be used to quickly kind of approximate

 

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the the capillary limit and we have some tools to help you out as you go through that process

 

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so the main ones are diameter so the larger diameter you have the more power you can move

 

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the length of the heat pipe again how you have to overcome all the pressure forces in your system

 

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so the the longer you are the the more you have to overcome and that can become a factor orientation

 

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as i discussed and then the two driving ones are the fluid properties and the wick properties

 

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so those are fluid properties are mainly defined by your fluid selection and the

 

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wick properties are where a company like ACT could come in and help you out in terms of

 

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how fine of a poor radius and and what type of the permeability you might need to achieve your goals

 

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so in very quick approximations, we do have a calculator online

 

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and this is a really good initial source to help you size your heat pipe

 

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and so i would recommend going on there and we’ll go through an example of using

 

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that calculator later on but just to kind of keep going through the design progression here

 

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some of the the other considerations are how it’s going to integrate into your system

 

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how you can bend it how you can pick up heat of various components so we do want to give kind of

 

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some sense of what’s possible here and the first thing is the standard pipe sizes so we can make a

 

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heat pipe out of pretty much any standard tubing that is available you can see some of the the

 

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standard sizes there three millimeter up to eight millimeter and an eighth of an inch up to half an

 

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inch is is very typical in copper water type heat pipes we’ve gone much larger than that in certain

 

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ammonia based or liquid metal based heat pipes but there’s there’s no real limitation it’s mainly

 

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manufacturing considerations but those are very standard sizes that we use on a routine basis

 

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and then probably the more interesting thing here is the bending and flattening guidelines so this

 

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is a lot of what our customers will come and ask us is how tight can we bend a heat pipe and how

 

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flat can we make it before we’re really kind of straining the the design points of the heat pipe

 

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and the recommendation there is for bending it’s it’s three times the outside diameter

 

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so that would be a center line bend radius so if you’re bending a heat pipe like you see on the

 

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bottom right one that center line bend radius around that that 90-degree leg you see there

 

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is about three times the outside diameter and that’s where you won’t hurt your performance

 

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vastly if you go much tighter you have the potential to limit your performance you also have

 

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the potential to kind of crank the metal envelope and cause potential issues in the manufacturing

 

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and bending steps as well so the guideline for bending is three times the outside diameter

 

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for flattening we typically random recommend two thirds the od again that’s where you still

 

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have significant vapor space to move decent power the more you fly in the more you will

 

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impact the performance capabilities so instead of calculating your capillary limit for instance

 

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with the round diameter you’re actually going to a hydraulic diameter as you flatten the pipe

 

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so you’re limiting that vapor space and and limiting your performance but two-thirds is

 

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a good kind of guideline to keep you moving significant amount of heat through your system

 

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and then in terms of integration there there are several options mechanical fit like press

 

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fit type type heat pipe integration but in most cases you want some type of bond there so

 

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in many cases we’ll do epoxy which is not as good of a thermal performer or mechanical properties as

 

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a solder but still gives you kind of a lower cost and you don’t need to nickel plate aluminum if

 

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you’re integrating into aluminum as you would with solder but in most cases solder is the the ideal

 

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choice and most of our customers prefer a solder it does give you that really nice mechanical and

 

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thermal interface and after nickel plating you can integrate into aluminum or many other base metals

 

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and now we’ll talk about modeling thermally so in your thermal resistance models there’s a

 

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couple different resistances to consider here and we’ll we’ll talk at length about how to model the

 

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heat pipe in general and modeling cutting some corners to model the system but really you

 

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want to look at these different areas so um the case to to heat pipe evaporator

 

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that’s conduction through either your your solder interface your epoxy interface or or some type of  thermal interface like a gap pad you have your

your heat pipe which is as i mentioned that two to five degree delta t across the length of the heat pipe and then you have your from the point of the

 

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heat pipe to your fin structure which is again typically conduction or some type of interface

 

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there and then your rise above ambience going from your your fins to the air so all those needs to be

 

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considered to properly design your system to meet your your maximum case temperatures make sure you

 

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don’t exceed your maximum case temperatures but what we’ll focus on here is is really

 

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how to model the the heat pipe and the conduction areas around the heat pipe

 

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so one of the easiest ways to model a heat pipe is the basic conduction rod and this

 

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actually gives you fairly good results and would be a high recommendation

 

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if you’re looking for that first order approximation so you can basically

 

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try to trick your system into showing two-phase performance with a single um conduction element

 

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and the way we recommend you do this is you start by inputting what would look like heat pipes in

 

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your system and then you assign them an effective thermal conductivity of around 10 000 watts per

 

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meter k and that effective thermal conductivity of a heat pipe is going to vary based on length

 

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so if you can meet your if you can operate as a heat pipe the shorter the heat pipe is the lower

 

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that thermal conductivity is because you have the same delta t across a shorter length than as if

 

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you’re going longer distances but what we would recommend is start with 10 000 watts per meter k

 

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run your simulation and then check your delta t from hottest to coldest point along your heat pipe

 

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and then adjust that that 10 000 mass per meter k until you get within that two to

 

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five degree temperature range so if you want to be conservative maybe go to the the five degree

 

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temperature difference so for instance if you have if you have a heat pipe that’s showing if

 

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you input the 10 000 watts per meter k and you’re showing an 8 degree temperature difference go

 

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ahead and increase that that effective thermal conductivity so you get that 8 degrees down to

 

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the the 5 degrees and that’s kind of a good approximation of what might be achieved

 

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with the heat pipe and i will say that the five degrees is fairly conservative so you can

 

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a lot of times beat that in your models but in um in a real world case where you’re looking

 

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for some conservatism that’s a that’s a nice first order approach to modeling heat pipe

 

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the second which is even more basic is modeling the entire high cave plate so high k plate is a

 

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act’s term for high thermal conductivity plates which is embedded copper water heat pipes into

 

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aluminum heat spreaders and we can make high k plates out of most geometries in aluminum

 

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surfaces if you can if you can machine in you have enough area to integrate a heat pipe we can

 

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typically turn it into a high k plate and we’ve done models in um going around corners so both

 

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two-dimensional and three-dimensional high cape plates have been achieved so there are there

 

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are some design variability in terms of how we can integrate the heat pipes but in most cases

 

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if if you have enough thickness to get the heat pipes in there we can turn it into a high k plate

 

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and this creates a really nice approach to very easily model thermal performance improvements

 

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so in aluminum 6061 is what most designers use as their heat spreaders that’s a thermal conductivity

 

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of about 167 watts per meter k so changing from aluminum to a high k plate will increase that

 

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that thermal conductivity dramatically and in real world results what we have seen is between

 

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500 and 1200 watts per meter k so when i say real world i mean we’re not kind of tricking the the

 

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system to put a heat pipe in the most favorable condition and put a heat heat source at one end

 

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heatsink at the other end we’re looking at

real world applications where you may have

 

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multiple components and multiple heat sinks and

you’re designing a heat pipe network to achieve

 

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the desired results or best case results and then

what we’ll do is go back into our models after

 

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we’ve performed thermal performance testing and

we’ll just increase the thermal connectivity

 

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until we match our performance testing so it’s

it’s a very fair comparison to say somewhere

 

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in that 500 to 1200 watts per meter k range is

where you’ll land and again that variability or

 

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that range is based on how much work the heat

pipe is doing so how long the heat pipe is and

 

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how much benefit you’re getting from the more or

less short-circuited thermal path of the heat pipe

 

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so we’ll talk about some examples later

on but for for one quick example that

 

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most of our customers are familiar with a

6u conduction card which is around um like

 

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nine by six inches that that is typically in

the six to seven hundred watts per meter k range

 

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so could have components located various places

along the surface but we can usually achieve

 

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somewhere kind of in the middle of that range to

give you a sense so again here to kind of make it

 

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easy on you we’re going to suggest using a thermal

conductivity of 600 watts per meter k so again if

 

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you have any real distance or or xy direction to

move heat and a localized hotspot that’s something

 

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that is usually very achievable and we’ve

proven now with with many types of these designs

 

0:22:58.320,0:23:04.880

and the next one and i guess the most complex

to model um is the what we call kind of the the

 

0:23:04.880,0:23:10.960

lumped approach where we uh more or less lump

some of the resistances of getting the heat

 

0:23:10.960,0:23:16.480

into the vapor space and then use a very

isothermal vapor space along the the inside of

 

0:23:16.480,0:23:23.040

the heat pipe and this gives you a nice more real pproximation because it does take into account

 

0:23:23.040,0:23:30.640

thermal interface the the heat pipe wall the wick structure and and some of those more granular

 

0:23:30.640,0:23:36.640

resistances that you would experience in a real world system but it does take some of the detailed

 

0:23:36.640,0:23:43.280

modeling as from those various resistances out of the equation so you don’t need to model two phase

 

0:23:43.280,0:23:50.000

flow you don’t need to model very high heat fluxesthat have very small wick structures and things

 

0:23:50.000,0:23:58.480

like that so it’s a way to kind of get a little more detail but provide a realistic and accurate

 

0:23:59.120,0:24:05.280

prediction without kind of taking significant computational time to run these models

 

0:24:07.680,0:24:14.320

so with that model we’ll talk about in a little more detail as we go through so

 

0:24:14.320,0:24:20.080

this example is trying to transfer 25 watts against gravity at room temperature so now

 

0:24:20.080,0:24:25.360

we’ll kind of run through all the steps of the lump model in in one kind of straight shot to

 

0:24:25.360,0:24:32.880

give you an idea of all the the various components so the first step is to go on to acts website and

 

0:24:32.880,0:24:40.320

find the heat pipe calculator under resources and

basically input your your guesswork at what the

 

0:24:40.320,0:24:48.800

heat pipe geometry might look like so in this

case we took the 25 watts there and we we had

 

0:24:48.800,0:24:54.160

it in a system you could see the the geometry

there we we kind of determined what the heat by

 

0:24:54.160,0:25:00.480

heat pipe might look like in in its configuration

based on the the source and sink conditions so we

 

0:25:00.480,0:25:06.160

had a total length of 3.1 inches a one inch

evaporator which is the the heat source zone

 

0:25:06.720,0:25:14.000

and a um a very small condenser less than one inch

on the condenser which gave a 1.32 inch adiabatic

 

0:25:14.000,0:25:18.640

zone so with those inputs and you can

see the figure over here to the right

 

0:25:18.640,0:25:24.000

those inputs actually output this these curves

of heat pipes which is the capillary limit

 

0:25:24.880,0:25:29.840

for various diameter heat pipes and you can

see the the red numbers there are the only

 

0:25:29.840,0:25:35.440

inputs required in our in our calculator and then

you can use those curves to figure out exactly

 

0:25:36.000,0:25:41.040

where you’re going to be operating and what

performance you need so in this case we had

 

0:25:41.040,0:25:49.040

an operational range of a little under 20 degrees

to about 100 degrees c and so we needed to operate

 

0:25:49.600,0:25:55.840

across that entire um curve and so there we’re

showing that a four millimeter heat pipe is needed

 

0:25:58.320,0:26:01.920

so now you know the kind of the diameter

of the heat pipe you can go into your

 

0:26:01.920,0:26:09.120

your modeling approach so now diving into an

example here with the the lump model method

 

0:26:09.760,0:26:15.440

this is where we’re going to determine

effective conductivity of several

 

0:26:16.960,0:26:24.000

paths to get the the heat into the heat pipe

and then there again we don’t want to model

 

0:26:24.000,0:26:28.880

each of these individually because they’re

going to be very thin it’s going to bog down

 

0:26:28.880,0:26:38.160

your computational time so what we are trying

to do here is create a sum of all the resistance

 

0:26:38.160,0:26:43.360

is in there so you can see the calculations

there as you go through your resistance

 

0:26:43.360,0:26:51.280

you have a resistance through a solder so you you

approximate that based on the thickness the the

 

0:26:51.280,0:26:56.880

length that you need to transfer heat through that

solder and the effective um or the actual thermal

 

0:26:56.880,0:27:03.040

conductivity of that solder itself so then you can

approximate the resistance of that solder again

 

0:27:03.040,0:27:09.920

same thing for the copper wall the copper wall for

a four millimeter pipe is is twelve thou and there

 

0:27:09.920,0:27:15.600

you can use the the copper thermal conductivity

and output of resistance for that as well

 

0:27:16.640,0:27:21.840

and then the wick material and evaporate

evaporation and condensation areas

 

0:27:21.840,0:27:28.160

we give an approximation here of a very

low thermal resistance in those areas and

 

0:27:29.280,0:27:34.560

lumping those together we want to create a model

that again you can calculate in in realistic time

 

0:27:35.200,0:27:38.720

to to create that first order approximation

so we’re recommending that you

 

0:27:39.600,0:27:48.800

model them as um 40 000 so that that won’t create

too thin of a surface to allow you to model it and

 

0:27:48.800,0:27:54.880

basically to create that effect of connectivity

you take all those different areas and you

 

0:27:54.880,0:28:01.520

output your effective connectivity and

with those results you get 26.7 watts

 

0:28:02.160,0:28:06.080

meter k as your as your effective

conductivity through that interface

 

0:28:07.200,0:28:13.520

so that’s again getting the heat into the

the vapor space at the evaporator surface and

 

0:28:13.520,0:28:19.120

getting it out of the vapor space on the condenser

surface so that’s an approximation that can use as

 

0:28:19.120,0:28:25.360

your lumped envelope material that can take into

account the solder the wall and the wick structure

 

0:28:27.440,0:28:34.000

and then from there we want to put a value in

for the effective thermal conductivity of the

 

0:28:34.000,0:28:39.440

vapor space and the vapor space

is going to be nearly isothermal

 

0:28:39.440,0:28:48.240

because of the the um properties of fluid

vapor it’s going to be very very low

 

0:28:48.240,0:28:53.840

thermal resistance across the vapor space so

the approximation we’re using here is 4a’s law

 

0:28:54.960,0:29:00.240

and going across that length i will say

this is a fairly conservative approximation

 

0:29:00.240,0:29:06.560

so in most cases you’ll you’ll see even a

lower delta t than this across the vapor space

 

0:29:06.560,0:29:12.160

specifically but as a nice approximation you

could use fourier’s law which takes the the

 

0:29:12.160,0:29:20.880

power the effective length um and the the area

in delta t and again we’re putting in some some

 

0:29:20.880,0:29:26.240

values in there um for delta t where we’re

saying two degrees as your your delta t which

 

0:29:26.240,0:29:31.840

again is very conservative but should give a nicer

approximation of what the effect of conductivity

 

0:29:31.840,0:29:36.000

and that value is going to be very high because

again it’s very isothermal in that vapor space

 

0:29:38.240,0:29:44.960

so going from there you have all the inputs to

to run your model so what we did there again

 

0:29:44.960,0:29:50.320

just to recap is will a heat pipe transfer the

required power so that’s your first thing you can

 

0:29:50.320,0:29:57.920

have a no go no go on if a heat pipe can move the

amount of heat and what size heat pipe you might

 

0:29:57.920,0:30:02.400

might need once you have the size of the

heat pipe you put it into your model say

 

0:30:03.040,0:30:07.840

do i have enough thickness here can i manipulate

it within my model to get the desired results

 

0:30:08.880,0:30:14.080

and again if there’s any challenges there let us

know a ct can certainly help out in some of the

 

0:30:14.800,0:30:19.120

practical considerations for integrating heat

pipes and then from there we determine the

 

0:30:19.120,0:30:25.040

effect of conductivity of the various inputs so

the summed model of getting the heat into and

 

0:30:25.040,0:30:30.720

out of the heat pipe or into and out of the vapor

space and then the vapor space itself which is a

 

0:30:30.720,0:30:36.800

very high effective thermal conductivity and from

there you can input your your heat loads into your

 

0:30:38.000,0:30:43.520

cfd model or or basic conduction model and

you can put your sink condition so your

 

0:30:43.520,0:30:49.360

ambient air temperature or just the heat transfer

coefficient to simulate your heat sink and from

 

0:30:49.360,0:30:52.960

there you can run your model and hopefully

get the desired results you’re looking for

 

0:30:54.640,0:30:59.760

and just one example of where we went

through the steps on a fairly small

 

0:30:59.760,0:31:04.000

conduction card and and this was actually a

fairly good approximation for the inputs we

 

0:31:04.000,0:31:11.760

used in this case we we had the actual hardware

where we we tested so we put in the 25 watts at

 

0:31:11.760,0:31:21.200

that interface and we tested and got the results

of about 80.3 degree interface temperature there

 

0:31:21.200,0:31:28.960

and then we ran the model in in both ways so the

more detailed model was um was fairly accurate so

 

0:31:28.960,0:31:36.640

it got us within um within a 1.2 percent error

and again because some of the vapor space um

 

0:31:37.680,0:31:43.760

approximations were somewhat conservative we were

actually under predicting performance of the heat

 

0:31:43.760,0:31:49.520

pipe solution there and then looking at a model

using the effect of conductivity of 500 watts per

 

0:31:49.520,0:31:56.960

meter k again um a little under predicting the

performance there which is why we typically say

 

0:31:56.960,0:32:02.800

600 watts per meter k i think we use 500 watts

per meter k in this model because the distances

 

0:32:02.800,0:32:08.800

were a little shorter than than a typical

high k plate but in general no matter what k

 

0:32:09.360,0:32:15.840

what you’re using you can get fairly close to the

results and if you’re within you know a couple

 

0:32:15.840,0:32:22.400

degrees or within somewhat margin of error that’s

when you call act and we can help kind of guide

 

0:32:22.400,0:32:28.960

you through the steps in getting a very detailed

and accurate model so then you can say do we want

 

0:32:28.960,0:32:33.360

to go through the steps of prototyping testing

this and going forward with the heat pipe solution

 

0:32:34.960,0:32:41.440

so again just to wrap up heat pipes are highly

reliable and they can be effective components

 

0:32:41.440,0:32:46.560

in thermal design they are used in a lot of

real world applications for electronics cooling

 

0:32:47.360,0:32:52.400

avionics type applications so there’s not

really many environments which heat pipes

 

0:32:52.400,0:32:58.240

have not successfully operated but there are a lot

of practical considerations in in each environment

 

0:32:58.240,0:33:03.280

um so thermal performance is one of many

considerations and those type of things but

 

0:33:03.280,0:33:10.320

if you have a functioning heat pipe operating

within its ability they are very reliable and

 

0:33:10.320,0:33:17.760

long-lasting devices they can be easily integrated

into new and existing designs so if you know early

 

0:33:17.760,0:33:24.080

on that you’re going to have a thermal challenge

that can be alleviated with advanced conduction or

 

0:33:24.080,0:33:27.920

point-to-point heat transfer going forward

with the heat pipe solution off the bat

 

0:33:27.920,0:33:35.120

is often a great approach but there’s many

cases where maybe your component power goes up

 

0:33:36.000,0:33:40.400

from one design to the next and you need to

retrofit heat pipes into an existing system that’s

 

0:33:40.400,0:33:46.960

also a really good opportunity to easily integrate

them without going through major changes to your

 

0:33:47.600,0:33:53.520

heat spreaders or heat sinks there are several

ways to effectively model heat pipes we talked

 

0:33:53.520,0:33:58.960

about several today and there’s even more

complex ways out there so again hopefully

 

0:33:58.960,0:34:03.760

this gives you some tools in the toolbox to give

a first order approximation of how a heat pipe

 

0:34:03.760,0:34:10.240

heat pipe might perform for you and then

the final is is act your trusted partner

 

0:34:10.240,0:34:16.240

we’re here as needed so if you run into challenge

running any of the models or thinking about some

 

0:34:16.240,0:34:21.120

of the practical considerations with heat pipes

give us a call we have engineers on standby ready

 

0:34:21.120,0:34:26.080

to kind of walk you through the process and and

help you out as you are thinking about heat pipes

 

0:34:28.640,0:34:36.080

and the final slide here just wanted to talk about

act your success is our success so we do take

 

0:34:36.080,0:34:40.880

um our partnerships very seriously and we

have received a lot of very good feedback

 

0:34:40.880,0:34:45.360

over the years so again reach out to us no matter where you are in the process

 

0:34:45.360,0:34:49.360

and we’d be happy to work with you and see if a heat pipe solution is right for your design

 

0:34:51.280,0:35:01.840

thank you all appreciate your time and please give us a call we look forward to working with you

 

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