hi harmonics, yes -- and soft clipping -- both! . I run
Hafler amps which have fairly good feedback circuits
for undesirable hi freq harmonics, but clipping is so
gross in any transistor amp (imho) that I use headroom
to stay away from it. . the best amp of all time, in
my collection, is the excelinear 600 which can be
pushed to more than 1000 watts per channel via
low impedance, with no clipping. . temp-controlled
fan. . what an amp. . David Hafler was a genius. -- j
.
p.s. I run a 400-watt Hafler amp in the living room
into everything -- delicious -- and we never turn
it off. . here's the 600::: https://search.yahoo.com/yhs/search;_ylt...
.

Tube amps have a particular warm sound, which people associate uniquely to tubes. I had a article which explained what this was from technically, and how it can be recreated in a solid-state amp, but it is lost, and I can not find it again! If I recall it was due to even harmonics and/or soft clipping.

that is an interesting link -- wish that I knew Norwegian
or Danish or whatever that language is! -- j
.

that's what we need, Rob -- nucs on wheels. . they
put 'em in submarines, don't they? -- j

p.s. lots of wheels, of course -- heavy!!!
.

now, that's an interesting idea! . nothing like the
juxtaposition of 1920s and 2020s tech!

I built a dynaco 35-watt-per-channel stereo amp
many years ago, and still have it. . smooooooth
sound and lots of heat! . we also still have an old
silvertone hi-fi. . it has a monster tube amp in it also. -- j
.

I haven't, but I have heard other horn-loaded speakers:
https://food52.com/shop/products/1837-an...

Shocking how much sound comes from these. Necessity is the mother of invention, and when 10 watts was a "monster" tube amp, horn loading efficiency was worked very hard.

in my experience, the thing which moves the air
is the most difficult part -- yes, like the ribbon tweeters
in the leaks. . the lightweight and rigid styrofoam
15s are also impressive.

but. . How In The Hell do they get all of that sound
out of a flat-screen tv or a tiny ipad? . blows my mind.

have you ever heard any of the nautilus-shell
shaped speakers? . supposedly, all of their drivers
are backed with TL tails. . WoW. -- j
.

Never saw this primer. Good one!

You are educating me further. I've not heard of the Leaks. They look wonderful. Early ribbon tweaters? Need to investigate this TL design!

I built a pair of TL style speakers for a friends front speakers in a home theater. They were beautiful. Magnificent sound reproduction. Got my brother a kit for a pair as a result.
I got a pair of Klipchorns in college in a weird deal. I wish I'd kept them, because they sounded magnificent too. One of these days, I may build a pair, if I don't get too consumed with direct amplification and integrated digital crossovers. As an engineer I waffle between wanting to do a beautiful acoustic design, and wanting to hit the full range, controlled by a simple digital crossover, leveraging modern technology. It's a smorgasbord!

yee-haaa! . I worked with a bunch of sub guys during
those 33 years -- the COBs were the most intriguing!

best speaker set of all time -- Dahlquist DQ10s
with a pair of DQ-1 subs;; second-best, the Leak
3090s. . transmission-line 15s. . I have the Leaks.
here::: https://search.yahoo.com/yhs/search?p=le...

k25 was amazing and y12 was even more
amazing. . learned the classified info business
very carefully, and can talk. . those guys in '41
when it all began were really sharp. . check out
their "primer" :::
free in wiki (wow!)::: http://en.wikipedia.org/w/index.php?titl...

the most fun unclassified thing from oak ridge is
the fact that they stole a ~900 mW power plant
from Chicago and built it at k25 in about 3 months --
as the story goes, "one man per brick." . that, and
the drawing labeled "oak ridge natural lavatory"
which was in the central files at k1001. . and the
story about the weekend when they had to make
an emergency run to chattanooga for condoms,
to avoid a plant shut-down.

war stories abound. -- j

BS ME - Machine Design focus (car guy)
MS ME - Robotics and controls
went to work (even though I had a free ride for PhD, dumb!)
Worked at GD Electric Boat for ~15 years.
Started consulting company, mostly for ExxonMobil projects ~2 yrs
Last 12 yrs, CTO at DRS Technologies (mid-tier defense company), doing many, many things (which ADD-me loves). One of them is selling electric propulsion systems to EB.

I'll have to get some ham inspiration from you. I'd given up on it in favor of too many other hobbies (wife calls them vices) a while ago. The closet thing is speaker-building. Also love to hear what it was like in the Manhattan Project when you were there!

ME -- machine design 71. . PE in 78. . aced the test,
but did not have to know that it's convection when
the intersection is solid to liquid. . dumb me thought
that convection pertained to solid-gas transfer.

I spent 33 years in the oak ridge manhattan project
plants, designing and managing. . I appreciate
your patience with me, Thor, since you're the ace
in this stuff. . Thanks!!! -- john

p.s. I just bought an 8-watt baofeng and a loooong
antenna. . also getting ready to put up a 2m/70cm
ant high above the chimney! . I'm a ham also.
.

Primary fluid is heated by the reactor core, and then transfers heat to the secondary fluid via:
Convection (primary fluid to the tube walls)
Conduction (through the tube walls, very low impedance to heat flux)
Convection (from the tube outer wall to the secondary fluid)
The main thermal impedance is the convection, and other the two convection processes, the one on the single phase / low density fluid side is a bigger challenge. If it is a gas, it needs a huge surface area to overcome the poor heat transfer.(like the air side on a car radiator).

A typical water to water heat exchanger looks like:
http://www.google.com/imgres?imgurl=http...
A typical liquid to high pressure gas heat exchanger looks like a recuperator:
http://www.aitesa.es/en/business-areas/p...

I think you get how it works, but the process to transfer heat from a surface to a moving fluid is convection, not conduction:
http://en.wikipedia.org/wiki/Heat_transf...

I needed a word to describe my inelegant focus on convection vs conduction, but also capture the inner geek. The HR woman in the office I work from uses it for me, when I won't give up on an argument.

Since you corrected me on the Baofung hand held radios, should I assume you are an EE or electronics hobbyist? I am an ME, but have worked 20+ years in the design of naval and oil & gas power distribution systems, converters, motors and generators.

you get the "new word" award for noodge!

I have always thought that boilers boil, like on a
steam locomotive, so I have assumed that the primary
fluid heats the secondary fluid (through conduction)
which then boils and blows on a turbine as steam.

no? . then, heating steam with hot primary fluid is
inefficient, compared with conduction through a
metal wall. . yes? -- j
.

Love that movie. MHD does work in seawater, but gets you a few knots, although there was a big stir when a news agency misprinted the speed of the Japanese Yamato 1 (looks real fast anyway).

BTW, both heat exchangers use convection on both sides. Conduction is only relevant through the solid walls of the heat exchanger. The fluids are moving, vs stationary. Conduction does work in liquids, but most liquids have very poor coefficients of heat conduction. Do I get the geek award for being such a noodge?

nope -- just pass a little water -- or other fluid / gas --
anywhere near it, and spin a turbine!!! -- j
.

Thor, I was just considering the inefficient use of
heat-transfer acreage -- conductance is many dozens
of times more efficient than convection! -- j

p.s. didn't you love it when "red october" mentioned MHD?
.

Thank You Sir! . more info about these plants -- Big
CO2 compressors needed to move the gas! -- j
.

The LFTR has better efficiency than a coal plant and much better efficiency than a standard Rankine cycle nuc plant. That is due to LFTR's high temperature. The high temperature is made possible by using a molten salt a coolant.

They have looked at a reheat cycle using super-critical CO2 as the working fluid to cool the salt and power the turbines. That approach decreased the size of the turbo-machinery, both the compressor and power turbines. There are typically several power turbines, with some of them directly driving the compressor and others driving a generator.

Lots, so we don't let the government do it (and no I don't believe you have to tap the magma to extract enough heat/energy to be worth while).

So we drill down into the magma of a super volcano under Yellowstone National Park?

What could go wrong with that?

With a gas, and no phase change, you have the closed Brayton Cycle. Expensive equipment, essentially running the high pressure, hot gas (Th) through a gas turbine and, then cooling it to increase density in a heat exchanger (Tl) then taking the cooler, lower pressure gas, back to the heat exchanger-side high pressure with a compressor. A typical gas turbine is a open Brayton Cycle. The closed cycle is additionally problematic depending on the working fluid. Helium is inert, and nice for heat transfer, but a royal pain to work with, because it will escape through anything. It will even migrate through metal, being the smallest atom on the periodic table.

Think you mean "effective" vs "efficient" in heat transfer from a liquid to gas. The problem is all on the gas side, where the density and specific heat is low and you need a huge surface area to transfer the heat. Both are very "efficient" though, depending on how you choose to measure efficiency, but power out/power in is going to be >90% in both cases.

In any case, this side thread started because I questioned the "safest" assertion. The nuclear (primary) side sounds kind of nice, but uses some nasty chemicals. The secondary side is dangerous, just like any steam turbine system. If a Brayton is used, very high temperatures are needed to get reasonable efficiencies, and the equipment is very expensive and non-standard.

I always had a soft spot in my heart for the old liquid Sodium reactors. Magnetohydrodynamic (MHD) pumps work beautifully in conductive fluids (unlike water), and valves can just be cooling loops around the pipe, freezing the molten metal! Man do they have power density, but that hot sodium is nasty, caustic stuff.

I was thinking of the heat of vaporization of water,
converted from liquid to steam, which is not happening
with helium -- or whatever it is which stays gaseous.
heat transfer is best, of course, from liquid to liquid,
and much less efficient from liquid to gas. -- j
.

There are primary and secondary loops. The primary loop is high temperature, but low pressure in this case. The secondary loop is either water (steam in a conventional Rankine Cycle, which is typical) or a gas in a Brayton Cycle (non-typical). Both cycles are inefficient from a typical point of view (20-40%), but not from a thermal cycle point of view.

My point was the low pressure is a nice story for the primary loop, but the secondary loop is always going to be very hot and very high pressure.

I don't know how big the "super volcano" under Yellowstone National Park is, but it seems we could be tapping the virtually unlimited amount of energy there with fairly "simple" technology. Maybe such would make lots of other energy technologies more affordable if, for example, we got 90% of our electricity there. Natural gas, refined petroleum and even electrolysis derived hydrogen could then be used for transportation. Don't get me wrong, I love nuclear power, but it seems it's (artificial) baggage makes it unlikely for the near term

You are correct. The French and others had huge problems with liquid sodium. It ate through everything. That's why the first attempt at these type of reactors was abandoned in the early 80's. Back then they were called Breeder Reactors.