Re: H2 burner

Internal combustion engines are limited by thermodynamics. The ratio
of hottest temperatures versus lowest temperatures limits the
efficiencies of these sorts of engines.

http://en.wikipedia.org/wiki/Carnot_efficiency#Efficiency


Maximum efficiency = 1 - Tc/Th

Where Th=hot temperature (absolute terms Kelvin or Rankine)
Tc= cold temperature (again absolute terms Kelvin or
Rankine)

Hydrogen fuel can burn hotter than hydro-carbon fuels, but
metallurgical considerations limit temperatures anyway to about 1,000C
- or 1,273K. If the exhaust temperature is say 500K then efficiency
cannot exceed 60% or so. Exhaust temps of 300K increases efficiency
to 76% - at the great expense of decreasing specific power and
reducing power to weight due to increased air handling and heat
transfer area. (higher temps transfer more energy per unit area -
and per unit weight - than lower temps - large areas not only mean
more material, but more costs as well)

Generally speaking lowest cost and lowest mass per unit weight is
favored - at the expense of efficiency

Here is a partial list of the heat engines that have been developed
over the years. Due to materials limitations as well as power and
cost limitations, they are limited to 20% to 60% efficiency - with the
higher efficiencies going to the stationary applications where weight
and cost are higher. Higher power lower mass lower cost systems tend
to have higher exhaust temps and lower peak temps and pressures (which
are related in most cases) - which reduce efficiency. Also, variable
loading and speeds take their toll in applications. This is why
hybrids get better mileage than direct drive engines. Hybrids can be
tuned to run very efficiently at one speed, and be switched on when
batteries need recharging, and switched off when batteries are full -
while the electrical management system takes the place of the
transmission. A continuously variable mechanical transmission with
flywheel can have much the same impact as a hybrid, at potentially
lower costs.

http://en.wikipedia.org/wiki/Otto_cycle#The_Otto_cycle
http://en.wikipedia.org/wiki/Diesel_cycle
http://en.wikipedia.org/wiki/Brayton_cycle
http://en.wikipedia.org/wiki/Rankine_cycle
http://en.wikipedia.org/wiki/Ericsson_Cycle
http://en.wikipedia.org/wiki/Atkinson_Cycle
http://en.wikipedia.org/wiki/Lenoir_cycle
http://en.wikipedia.org/wiki/Miller_cycle
http://en.wikipedia.org/wiki/Thermoacoustic_refrigeration
http://en.wikipedia.org/wiki/Peltier-Seebeck_effect
http://en.wikipedia.org/wiki/Pyroelectricity
http://en.wikipedia.org/wiki/Thermionic_emission


http://en.wikipedia.org/wiki/Continuously_variable_transmission
http://en.wikipedia.org/wiki/Flywheel_energy_storage

Another possibility for using heat is TPV - thermophotovoltaics. This
is the same as a solar cell, but uses heat energy

http://en.wikipedia.org/wiki/Thermophotovoltaic

Even though the mechanism is quite different than in the systems
described above, TPV is still a heat engine - similar to many of the
thermo-electric engines described above.

One way efficiencies might be improved, without dramatically
increasing costs and maintaining or improving power to weight, is to
make engines smaller and run them in parallel. When the size of an
engine changes, the surface area changes as the square of the
dimension, and the volume changes as the cube of the dimension. So,
reducing an engine to 1/2 the size of a similar engine, decreases its
surface area by 1/4 and its volume by 1/8th - so its surface area per
unit weight goes by by a factor of 2 - allowing us to operate at a
different regiion of efficiency while maintaining the same amounts of
materials even though surface areas are larger per unit volume.

Alright, this is taken to its extremes with MEMs based engines (micro-
electro-mechanical systems)

http://en.wikipedia.org/wiki/MEMS
http://en.wikipedia.org/wiki/Micropower
http://berkeley.edu/news/berkeleyan/2001/04/10_cmbus.html

In the end, the real factor is the total cost of the engine for the
given application over its life cycle. Blind pursuit of highest
efficiency at any cost - typically does not achieve this - a cost-
effective efficiency however varies with the cost of energy.

From the beginning of the industrial age in the 1840s thorugh 1960s-
the cost of energy decreased consistently at about a 5% per annum
rate. Oil produced at an inflation adjusted $200 per barrel in 1860
fell to $2 per barrel by 1960. Over that same period the use of
energy by civilization increased exponentially, and with it, the
benefits of industrial living increased living standards. Slavery
was ended, the work week was shortened from 80 hours to 60 hours to 40
hours, civil rights were enacted, the middle class emerged, retirement
at 65 was commonplace, all byproducts of lower energy costs.

From 1960 to the present day, energy costs have risen at an average 8%
per annum. Oil now exceeds $100 per barrel - $20 per barrel when
measuring in 1960s dollars. However, increased automation and
efficiency improvements have resulted in a holding action against
economic decline. We perceive this as limits to our industrial
capacities and increasing costs of things today that were done more
cheaply in the past. Despite this, families have two wage earners,
reinstituting for many 80 hour work weeks, and many people hold two
jobs, reinstituting 60 hour work weeks. Increasing conflicts over
material shortages will lead to a reversal of civil rights, likely
along wealth lines rather than race lines, and eventually with higher
and higher energy costs - we will see slavery re-instituted in moder
guise - as some sort of debt instrument that is carried from
generation to generation.

Of course if we could reduce the cost of GENERATION of PRIMARY energy
from nuclear and solar (which is also nuclear) sources we can usher in
an age where energy is too cheap to meter.

In the 1960s people looked forward to the 2010s with enthusiasm.
Why? They predicted that high temperature nuclear reactors made very
cheaply - but safely and reliably - would make energy too cheap to
meter. With high temperature nuclear power we'd have low cost
hydrogen created thermolytically from water. So, expert opinion in
the 1960s had every reason to believe that the 5% reduction in energy
costs woudl continue for another 50 years - and today we'd be paying
the equivalent of $0.15 per barrel (15 cents) - and this combined with
increased automation and efficiencies obtained at low cost would
transform life on Earth. Our average GDP in the USA would be about
$1,000,000 per person per year - and we'd have universal health care,
universal PhD, a 20 hour work week, and retirement at age 40.

None of this happened. The high temperature nuclear reactor was
shelved with the election of Richard Nixon, and his appointment of
major oil companies as advisors of energy policy for this nation.
With the election of Jimmy Carter, a Navy nuclear engineer, who vowed
to do something about the shortages brought about under Nixon, there
was hope that the BNL studiy created by Johnson/Kennedy and ignored by
Nixon would get some action - and by 1980s we'd have energy too cheap
to meter. The week Congress acted on Carter's program Three Mile
Island melted down, and Jane Fonda's movie China Syndrome hit the
theaters. So, Congress passed legislation establishing huge programs
for the DOE, but avoiding any major development of high temperature
nuclear reactors called fo rin the BNL study as a pathway to energy
that was too cheap to meter. Since that time, proponents of high
temperature nuclear reactors have fought an uphill battle - which has
resulted in the DOE Gen IV reactor proposal - which is slated for
development around 2030 - about the time oil price increases no longer
increase the value of oil reserves for those who own them since at
the prices projected for that date, the marginal value of oil equals
its marginal cost - and utilization goes down, reducing the value of
reserves despite their high cost relative to cost of production.

http://en.wikipedia.org/wiki/Generation_IV_reactor

This technology was available as early as 1950 -it has merely been
classified and sidestepped for 60 years-

http://en.wikipedia.org/wiki/Project_Pluto

Nobody knows why - some suspect a conspiracy. Similar to the
conspiracy that ended street cars in the USA

http://en.wikipedia.org/wiki/National_City_Lines

Outside the USA, electric trains and streetcars, driven by nuclear
power plants, move lots of people seamlessly in places like
Switzerland, vastly reducing their use of oil natural gas and coal
without reducing their standards of living

http://www.vbz.ch/vbz_opencms/opencms/vbz/english/index.html






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