Monthly Archives: April 2013

Zen and the hotdog vendor (a joke)

What did the Zen master ask from the hot dog vendor?

“Can you make me one — with everything?”

The vendor (so the story goes) replied “That will be $1.50.” The Master handed him $10 and the vendor handed him a hot-dog and said, “change comes from within.” (thought you’d like to know).

If you think this is funny, you may also like my previous Zen joke or (for all I know), my recent personal relationship cartoon.

Camless valves and the Fiat-500

One of my favorite automobile engine ideas is the use of camless, electronic valves. It’s an idea whose advantages have been known for 100 years or more, and it’s finally going to be used on a mainstream, commercial car — on this year’s Fiat 500s. Fiat is not going entirely camless, but the plan is to replace the cams on the air intake valves with solenoids. A normal car engine uses cams and lifters to operate the poppet valves used to control the air intake and exhaust. Replacing these cams and lifters saves some weight, and allows the Fiat-500 to operate more efficiently at low power by allowing the engine to use less combustion energy to suck vacuum. The Fiat 500 semi-camless technology is called Multiair: it’s licensed from Valeo (France), and appeared as an option on the 2010 Alfa Romeo.

How this saves mpg is as follows: at low power (idling etc.), the air intake of a normal car engine is restricted creating a fairly high vacuum. The vacuum restriction requires energy to draw and reduces the efficiency of the engine by decreasing the effective compression ratio. It’s needed to insure that the car does not produce too much NOx when idling. In a previous post, I showed that the rate of energy wasted by drawing this vacuum was the vacuum pressure times the engine volume and the rpm rate; I also mentioned some classic ways to reduce this loss (exhaust recycle and adding water).

Valeo’s/Fiat’s semi-camless design does nothing to increase the effective compression ratio at low power, but it reduces the amount of power lost to vacuum by allowing the intake air pressure to be higher, even at low power demand. A computer reduces the amount of air entering the engine by reducing the amount of time that the intake valve is open. The higher air pressure means there is less vacuum penalty, both when the valve is open even when the valve is closed. On the Alfa Romeo, the 1.4 liter Multiair engine option got 8% better gas mileage (39 mpg vs 36 mpg) and 10% more power (168 hp vs 153 hp) than the 1.4 liter cam-driven engine.

David Bowes shows off his latest camless engines at NAMES, April 2013.

David Bowes shows off his latest camless engines at NAMES, April 2013.

Fiat used a similar technology in the 1970s with variable valve timing (VVT), but that involved heavy cams and levers, and proved to be unreliable. In the US, some fine engineers had been working on solenoids, e.g. David Bowes, pictured above with one of his solenoidal engines (he’s a sometime manufacturer for REB Research). Dave has built engines with many cycles that would be impractical without solenoids, and has done particularly nice work reducing the electric use of the solenoid.

Durability may be a problem here too, as there is no other obvious reason that Fiat has not gone completely camless, and has not put a solenoid-controlled valve on the exhaust too. One likely reason Fiat didn’t do this is that solenoidal valves tend to be unreliable at the higher temperatures found in exhaust. If so, perhaps they are unreliable on the intake too. A car operated at 1000-4000 rpm will see on the order of 100,000,000 cycles in 25,000 miles. No solenoid we’ve used has lasted that many cycles, even at low temperatures, but most customers expect their cars to go more than 25,000 miles without needing major engine service.

We use solenoidal pumps in our hydrogen generators too, but increase the operating live by operating the solenoid at only 50 cycles/minute — maximum, rather than 1000- 4000. This should allow our products to work for 10 years at least without needing major service. Performance car customers may be willing to stand for more-frequent service, but the company can’t expect ordinary customers to go back to the days where Fiat stood for “Fix It Again Tony.”

How Theodore Roosevelt survived being shot

Two more pictures of Theodore Roosevelt. The first is an x-ray showing the bullet he received as he entered a hall to give a 90 minute speech in 1912. How he survived the shooting: he did nothing. He left the bullet stay where it was for the rest of his life. It seems that both McKinley and Garfield had died from infection of their shooting wounds after doctors poked around trying to extract the bullet. It’s quite possible that Lincoln died the same way (Lincoln’s doctor was the one who killed Garfield by poking around this way).X-ray of Teddy Roosevelt showing the bullet where he let it lie.

X-ray of Teddy Roosevelt showing the bullet where he let it lie. The stripes look like lead paint, used to mark the spot. 

Roosevelt knew from hunting that a shot animal could last for years with the bullet still inside him. Roosevelt (and his doctors) knew, or suspected, that his bullet had stopped in a place where it would be harmless unless someone tried to extract it.

T. Roosevelt with Rhino, 1909.

T. Roosevelt with Rhino, 1909. Teddy would be shot 3 years later, in 1912.

In the speech, Roosevelt said, “it takes more than that to stop a Bull Moose.” He ought to know. For more T. Roosevelt pictures, click here.

Most Heat Loss Is Black-Body Radiation

In a previous post I used statistical mechanics to show how you’d calculate the thermal conductivity of any gas and showed why the insulating power of the best normal insulating materials was usually identical to ambient air. That analysis only considered the motion of molecules and not of photons (black-body radiation) and thus under-predicted heat transfer in most circumstances. Though black body radiation is often ignored in chemical engineering calculations, it is often the major heat transfer mechanism, even at modest temperatures.

One can show from quantum mechanics that the radiative heat transfer between two surfaces of temperature T and To is proportional to the difference of the fourth power of the two temperatures in absolute (Kelvin) scale.

P_{\rm net}=A\sigma \varepsilon \left( T^4 - T_0^4 \right).  Here Pnet is the net heat transfer rate, A is the area of the surfaces, σ is the Stefan–Boltzmann constantε is the surface emissivity, a number that is 1 for most non-metals and .3 for stainless steel.  For A measured in m2σ = 5.67×10−8 W m−2 K−4.

Unlike with conduction, heat transfer does not depend on the distances between the surfaces but only on the temperature and the infra-red (IR) reflectivity. This is different from normal reflectivity as seen in the below infra-red photo of a lightly dressed person standing in a normal room. The fellow has a black plastic bag on his arm, but you can hardly see it here, as it hardly affects heat loss. His clothes, don’t do much either, but his hair and eyeglasses are reasonably effective blocks to radiative heat loss.

Human-Infrared.jpg
Infrared picture of a fellow wearing a black plastic bag on his arm. The bag is nearly transparent to heat radiation, while his eyeglasses are opaque. His hair provides some insulation.

As an illustrative example, lets calculate the radiative and conductive heat transfer heat transfer rates of the person in the picture, assuming he has  2 m2 of surface area, an emissivity of 1, and a body and clothes temperature of about 86°F; that is, his skin/clothes temperature is 30°C or 303K in absolute. If this person stands in a room at 71.6°F, 295K, the radiative heat loss is calculated from the equation above: 2 *1* 5.67×10−8 * (8.43×109 -7.57×109) = 97.5 W. This is 23.36 cal/second or 84.1 Cal/hr or 2020 Cal/day; this is nearly the expected basal calorie use of a person this size.

The conductive heat loss is typically much smaller. As discussed previously in my analysis of curtains, the rate is inversely proportional to the heat transfer distance and proportional to the temperature difference. For the fellow in the picture, assuming he’s standing in relatively stagnant air, the heat boundary layer thickness will be about 2 cm (0.02m). Multiplying the thermal conductivity of air, 0.024 W/mK, by the surface area and the temperature difference and dividing by the boundary layer thickness, we find a Wattage of heat loss of 2*.024*(30-22)/.02 = 19.2 W. This is 16.56 Cal/hr, or 397 Cal/day: about 20% of the radiative heat loss, suggesting that some 5/6 of a sedentary person’s heat transfer may be from black body radiation.

We can expect that black-body radiation dominates conduction when looking at heat-shedding losses from hot chemical equipment because this equipment is typically much warmer than a human body. We’ve found, with our hydrogen purifiers for example, that it is critically important to choose a thermal insulation that is opaque or reflective to black body radiation. We use an infra-red opaque ceramic wrapped with aluminum foil to provide more insulation to a hot pipe than many inches of ceramic could. Aluminum has a far lower emissivity than the nonreflective surfaces of ceramic, and gold has an even lower emissivity at most temperatures.

Many popular insulation materials are not black-body opaque, and most hot surfaces are not reflectively coated. Because of this, you can find that the heat loss rate goes up as you add too much insulation. After a point, the extra insulation increases the surface area for radiation while barely reducing the surface temperature; it starts to act like a heat fin. While the space-shuttle tiles are fairly mediocre in terms of conduction, they are excellent in terms of black-body radiation.

There are applications where you want to increase heat transfer without having to resort to direct contact with corrosive chemicals or heat-transfer fluids. Often black body radiation can be used. As an example, heat transfers quite well from a cartridge heater or band heater to a piece of equipment even if they do not fit particularly tightly, especially if the outer surfaces are coated with black oxide. Black body radiation works well with stainless steel and most liquids, but most gases are nearly transparent to black body radiation. For heat transfer to most gases, it’s usually necessary to make use of turbulence or better yet, chaos.

Metals and nonmetals

Hydrogen is both a metal an a non-metal. It says so on the specially produced coffee cups produced by my company (and sold by my company) but not on any other periodic table i’ve seen. That’s a shame for at least two reason. First, on a physiochemical level, while hydrogen is a metal in the sense that it combines with non-metals like chlorine and oxygen to form HCl and H2O, it’s not a metal in how it looks (not very shiny, malleable, etc.). Hydrogen acts like a chemical non-metal in the sense that it reacts with most metals to form metal hydrides like NaH CaH2 and YH3 (my company sells metal hydride getters, and metal membranes that use this property), and it also looks like a non-metal; it’s a gas like non-metallic chlorine, fluorine, and oxygen.

REB Research, Periodic table coffee cup

REB Research, Periodic table coffee cup

Most middle schoolers and high schoolers learn to differentiate metals and nonmetals by where they sit on the periodic tables they are given, and by general appearance and feel, that is by entirely non-scientific methods. Most of the elements on the left side of their periodic tables are shiny and conduct electricity reasonably well, so students come to believe that these are fundamental properties of metals without noting that boron and iodine (on the right side) are both shiny and conduct electricity, while hydrogen (presumably the first metal) does not. Students note that many metals are ductile without being told that calcium and chromium are brittle, while boron and tin (non-metals) are ductile. And what’s with the jagged dividing line: some borderline cases, like aluminum, look awfully metallic by normal standards.

The actual distinction, and the basis for the line, has nothing to do with the descriptions taught in middle school, but everything to do with water. When an element is oxidized to its most common oxide and dissolved in water the solution will be either acidic or basic. This is the basis of the key distinction: we call something a metal if the metal oxide solution is basic. We call something a non-metal if the oxide solution is an acid. To make sulfuric acid or nitric acid: you dissolve the oxides of sulfur or nitrogen respectively, in water. That’s why nitrogen and sulfur are nonmetals. Similarly, since you make boric acid by dissolving boron oxide in water boron is a non-metal. Calcium is a metal because calcium oxide is lime, a strong base. Aluminum and antimony are near borderline cases, because their oxides are nearly neutral.

And now we return to hydrogen and my cup. hydrogen is the only element listed as both a metal and a non-metal because hydrogen oxide is water. It is entirely neutral. When water dissolves in water the pH is 7; by definition, hydrogen is the only real borderline case. It is not generally shown that way, but it is shown as a metal and a non metal is on a cup produced by my company.

Zen Buddhist Joke

How many Zen Buddhists does it take to screw in a lightbulb?

Four: One to screw in the bulb;

One to not screw in the bulb;

One to both screw in the bulb and not screw in the bulb.

And one to neither screw in the bulb, nor not screw in the bulb.

Is funny because Buddhism aims at enlightenment — something that occurs by the simultaneous destruction and non-destruction of the darkness. Ah you got it: I hear one hand clapping.

Chernobyl radiation appears to cure cancer

In a recent post about nuclear power, I mentioned that the health risks of nuclear power are low compared to the main alternatives: coal and natural gas. Even with scrubbing, the fumes from coal burning power plants are deadly once the cumulative effect on health over 1000 square miles is considered. And natural gas plants and pipes have fairly common explosions.

With this post I’d like to discuss a statistical fluke (or observation), that even with the worst type of nuclear accident, the broad area increased cancer incidence is generally too small to measure. The worst nuclear disaster we are ever likely to encounter was the explosion at Chernobyl. It occurred 27 years ago during a test of the safety shutdown system and sent a massive plume of radioactive core into the atmosphere. If any accident should increase the cancer rate of those around it, this should. Still, by fluke or not, the rate of thyroid cancer is higher in the US than in Belarus, close to the Chernobyl plant in the prime path of the wind. Thyroid cancer is likely the most excited cancer, enhanced by radio-iodine, and Chernobyl had the largest radio-iodine release to date. Thus, it’s easy to wonder why the rates of Thyroid cancer seem to suggest that the radiation cures cancer rather than causes it.

Thyroid Cancer Rates for Belarus and US; the effect of Chernobyl is less-than clear.

Thyroid Cancer Rates for Belarus and US; the effect of Chernobyl is less-than clear.

The chart above raises more questions than it answers. Note that the rate of thyroid cancer has doubled over the past few years, both in the US and in Belarus. Also note that the rate of cancer is 2 1/2 times as high in Pennsylvania as in Arkansas. One thought is test bias: perhaps we are  better at spotting cancer in the US than in Belarus, and perhaps better at spotting it in Pennsylvania than elsewhere. Perhaps. Another thought is coal. Areas that use a lot of coal tend to become sicker; Europe keeps getting sicker from its non-nuclear energy sources, Perhaps Pennsylvania (a coal state) uses more coal that Belarus (maybe).

Fukushima was a much less damaging accident, and much more recent. So far there has been no observed difference in cancer rate. As the reference below says: “there is no statistical evidence of a difference in thyroid cancer caused by the disaster.” This is not to say that explosions are OK. My company, REB Research, makes are high pressure, low temperature hydrogen-extracting membranes used to reduce the likelihood of hydrogen explosions in nuclear reactors; so far all the explosions have been hydrogen explosions.

Sources: for Belarus: Cancer consequences of the Chernobyl accident: 20 years on. For the US: GEOGRAPHIC VARIATION IN U.S. THYROID CANCER INCIDENCE, AND A CLUSTER NEAR NUCLEAR REACTORS IN NEW JERSEY, NEW YORK, AND PENNSYLVANIA.

R. E. Buxbaum, April 19, 2013; Here are some further, updated thoughts: radiation hormesis (and other hormesis)

Detroit: maximum punishment

Some moths ago, I argued that getting rid of its extra-high minimum wage was perhaps the single best thing that Detroit could do to improve its bankrupt finances and to provide jobs for its youth. I argued that this living wage of $11 or $14/hr, depending on whether healthcare was provided, was too much for the city to pay for it’s minimal skill workers. I also argued that a lower minimum wage would help the city finances, and would allow the unskilled of Detroit to find jobs: it would provide the first rung of a ladder. Well, sort-of good news: Detroit’s living wage has been declared unenforceable by the Michigan Supreme court.

Unenforceable does not mean that wages will lower immediately: anyone working for the city will keep their high salary job, so the finances of the city will remain strained. Also, private companies can not lower anyone’s contracted wages. The only difference is that workers on non-city jobs who agree to be paid $7.50 to $14/hr, can no longer sue to recover additional dollars to meet Detroit’s “living wage.” Bit by bit I expect that more low-skilled workers will be hired, and that their wages will stabilize downward to a free-market value.

The next big things that are needed are reduced crime and increased population who are employed in businesses other than selling drugs or themselves. One way to reduce crime, I think is to have less-stiff minimum penalties for non-violent crimes like drug possession and driving with a suspended license. Currently the penalty for possession runs to 15-20 years. No one who spends that much time in prison will fit back into society. Let’s do them and ourselves a favor by reducing minimum sentences so that the normal sentence is only 1-5 years (ideally with < 1 oz marijuana possession punished by a fine).

Another horror is the penalty for driving with a suspended license. It’s $3000 for a start (a reasonable amount, I think), but then the state adds a $4000 per year penalty for the next 3 years: a total of $15,000. That’s too much for a minimum-wage earner to pay, but the minimum wage earner needs a car to get to work. So he/she can’t work, or he/she drives without a license or insurance. Is this what we want? Lets give a second chance and lower the penalty to produce more working, law-abiding citizens. There is nothing wrong with Detroit that could not be fixed by 200,000 more, law-abiding, employed Detroiters.

R.E. Buxbaum owns REB Research, a maker of hydrogen purifiers and hydrogen generators. We used to be located in Detroit, but are now in Oakland county, 1/2 mile north of the Detroit border.