Notable work on heat engines

This paper will be useful when building an efficient yet cheap heat engine. Heat engines are prevalent in all places where energy is converted from one form into another.

Nature 399, 335-338, 1999

A thermoacoustic Stirling heat engine

S. Backhaus and G. W. Swift

Abstract

Electrical and mechanical power, together with other forms of useful work, are generated worldwide at a rate of about 10¹² watts, mostly using heat engines. The efficiency of such engines is limited by the laws of thermodynamics and by practical considerations such as the cost of building and operating them. Engines with high efficiency help to conserve fossil fuels and other natural resources, reducing global-warming emissions and pollutants. In practice, the highest efficiencies are obtained only in the most expensive, sophisticated engines, such as the turbines in central utility electrical plants. Here we demonstrate an inexpensive thermoacoustic engine that employs the inherently efficient Stirling cycle. The design is based on a simple acoustic apparatus with no moving parts. Our first small laboratory prototype, constructed using inexpensive hardware (steel pipes), achieves an efficiency of 0.30, which exceeds the values of 0.10–0.25 attained in other heat engines with no moving parts. Moreover, the efficiency of our prototype is comparable to that of the common internal combustion engine (0.25–0.40) and piston-driven Stirling engines (0.20–0.38).

Fake or not art

How do you determine if art work is genuine or not? You may expect experts in the art world could tell the difference but there have been paintings sold for millions that were later deemed fake. Physics can actually come to the aid of art by telling if an art work is fake or not.

Lighting efficiency

Lighting efficiency for incandescent light bulbs are only around 2 to 3 percent. With fluorescent tubes, you may get around 15 percent. It would be interesting to find ways to improve on these figures. Just imagine the amount of energy we can save. The following may contain something relevant. René T. Wegh, Harry Donker, Koenraad D. Oskam and Andries Meijerink have written a paper in Science 1999, 283, 663 with the following abstract.

For mercury-free fluorescent lamps and plasma display panels, alternative luminescent materials are required for the efficient conversion of vacuum ultraviolet radiation to visible light. Quantum cutting involving the emission of two visible photons for each vacuum ultraviolet photon absorbed is demonstrated in Eu³⁺-doped LiGdF₄ with the concept of downconversion. Upon excitation of Gd³⁺ with a high-energy photon, two visible photons can be emitted by Eu³⁺ through an efficient two-step energy transfer from Gd³⁺ to Eu³⁺, with a quantum efficiency that approaches 200 percent.

Sizing and sorting DNA molecules

In 1998, Hou-Pu Chou, Charles Spence, Axel Scherer, and Stephen Quake found a way to size and sort DNA molecules. Their method is fast and requires few samples. This should be particularly useful in the medical industry. Proc. Nat. Acad. Sci. 1999, 96, 11

Stickiness theory

Researchers in Physical Review Letters, 1999, 82, 936 have shown that surface roughness on micron scales combined with air suction can be stickier than thermodynamic effects alone. This could be relevant in sports where stickiness is important. Well, stickiness is important in many other areas other than sport.

Nanotubes for sieving

Nanotubes can be used to separate atoms or molecules. The first simulations were in Physical Review Letters, 1999, 82, 956. One application is to separate hydrogen from the radioactive isotope tritium in water used to cool the nuclear fuel rods. There should be medical applications as well.

Re-reading Physics World magazine

I am re-reading the Physics World magazine from January 1999. It will be interesting to see how things have panned out.

No more cracks in paint using physics

The paint industry could be helped by some work done in (Phys. Rev. Lett. 98 218302). They have been investigating the factors involved in the cracking of paint as it dries.