The black coating improves heat loss by radiation. But, since very little of the actual heat loss from the condenser is by radiation (most is from convection), it doesn't really make much of a difference.
Putting a layer of something on the outside of the aluminum will indeed reduce heat transfer a little if that something is a poorer heat conductor than aluminum.... but indeed since a layer of paint is thin it doesn't really make much of a difference.
If I were making condensers, I would do black anodizing. You get a nice black surface, you don't get much change in heat transfer since there really is no coating, and you get something nice and hard that is much more resistant to corrosion.
And that's really the main issue... corrosion builds up and both provides an insulating layer and eventually eats the fins away until you don't have as much surface area anymore.
It's a simple pump and fan aided heat exchanger, not a "mass transfer system." Where'd you come up with that crap? The heat exchange is nearly all conduction and convection, so you goth the radiation part right
because that's what it is, technically speaking. it's not convection in the traditional sense - it's forced transfer of a medium typically characterized by its mass. you've heard of air conditioners rated by their tonnage haven't you?
technically, it's not convection because that is what occurs unaided.
WTF? That's got nothing to do with "mass transfer," which is a term used for other processes. I looked it up because I never heard the term used when talking about heat transfer. You won't find mass transfer conflated with heat transfer anywhere. Analogies only.
Kiss my ass with your condescending bullshit. . There's forced convection and natural convection. I was a trained Navy boilerman for
4 years, further studied heat exchange while in the Merchant Marine, worked in the power generating plants at U.S. Steel, had a stationary engineers license, and worked on plenty of car cooling systems. Nobody but you ever used the term "mass transfer" to describe a simple car cooling system heat exchange process. Only you. The term "mass transfer" is mostly used in chemical engineering. According to Wiki, "The driving force for mass transfer is typically a difference in chemical potential." Heat exchange is driven by temperature differences. You can study the details if you like. I'm done caring now.
why are you on a "tech" forum if you're not interested in using technical language? to put this another way, if people use language that you don't understand, why is it their problem not yours?
!!!
???
no, science only.
it's not condescending, it's helpful to people on a "tech" forum with an interest in understanding what they don't know.
i don't know where you got that little nugget - you don't cite a link - but there's no "chemical" potential here.
i do like. that's why i have studied them. why someone who doesn't and hasn't thinks they're better informed is the confusing bit.
pretzel logic given that you took the trouble to tell everybody what you think.
Mass is not being transfered across the system boundary. Only heat. Yes, water flows in the engine cooling system and air flows through the radiator, but no water is transfered into the air and vice-versa.
Yes, we've not only heard of it, but actually understand it. It has nothing to do with mass transfer. A ton in HVAC terms is the amount of energy it takes to transform a ton of ice at 32F into water. Again, no mass is transfered, it just melts.
That's just wrong.
You use Amazon as a reference for physics and engineering?
a room AC to cool a room with the volume of a dozen cars for $100.- Hide qu oted text -
For the same reason that it could cost several hundred to fix that room AC, if it failed. And the fact that the components of an auto AC are usually not very accessible. The evaporator for example, is buried in the dash. You can't just take off a couple pieces of outer sheetmetal off and get to everything right in front of you.... With labor rates at $100, what do you expect?
that's deliberate obfuscation. air [mass] is transferred within the greater body of itself. that's why "mass transfer" is used to describe the process which for free bodies is otherwise known as "convection" or forced systems, "advection".
AC to cool a room with the volume of a dozen cars for $100.
$1200 is if it's an easy job. I've heard of several that were nearly $2000. My Brotherinlaw's Volvo needed $2000 in repairs and a year later it broke again and they wanted another $2000 to fix it. He did as they hoped, he bought a new car.
BS. Convection is convection whether it's natural or forced. An example of natural convection is hot air rising above an electric stove burner. An example of forced convection is the air flowing through the car radiator. If we're all wrong, then maybe you can explain all the "convection ovens" being sold and used. I have two here in the house. Both have fans. When you select convection heating, the fans turn on to circulate air within the oven cavity. That is how a convection oven works. Very basic.
If you have some point, !!! doesn't make it. I would note that you accused me of obfuscation. YOU asserting that "tons" in an HVAC context has something to do with mass transfer, that it proves your point, now that's obfuscation. Tons in that context is a measure of heat energy, nothing more. I hope you accept that now.
I have, perhaps you should too. Here, it could not be spelled out any clearer:
formatting link
"Convection can be "forced" by movement of a fluid by means other than buoyancy forces (for example, a water pump in an automobile engine). In some cases, natural buoyancy forces alone are entirely responsible for fluid motion when the fluid is heated, and this process is called "natural convection." An example is the draft in a chimney or around any fire. In natural convection, an increase in temperature produces a reduction in density, which causes fluid motion due to pressures and forces when fluids of different densities are affected by gravity (or any g-force). "
It's particularly interesting that as an example, they actually use an auto cooling system. That should remove any doubt.
That link is to a book being sold on Amazon. It's a college engineering text book on heat and mass transfer. So, what on earth are you implying that picture of the book proves? That's a scientific reference? A book cover? Good grief.
Not, hardly. Read the introductory chapter of the granddaddy of all transport phenomena texts, Bird, Stewart, and Lightfoot. It's preview is available at
The first few paragraphs of Chap 0 and the table of processes on p. 4 (Table 0-2.1) (and where they're covered in the book) is sufficient.
This is a dual-loop, closed system forced convection heat transfer problem. No mass transfer in the analytic meaning thereof is occurring.
To me it seems you are being unnecessarily pedantic. It appears that the c hemical engineering usage of "mass transfer" would not be correctly applied to this system. I'm guessing because I'm not a chemical engineer, I'm a m echanical engineer. Mechanical engineers do not have the same precise usag e standard and very well might talk about mass transfer in this problem. C ertainly mass crosses the system boundaries at a high rate.
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