The sun., 1919-06-26
BRITAIN PRODUCES
NEW STEAM ENGINE
Still's Invention Heralded as
the Most Powerful Yet
Developed.
MORE COOLING DEVICES
Details Of Operation Are Ex-
planned Before Royal
Society Of Arts.
sp.c,ot co,rs.pondencs 10 rsr Sun

Special Correspondence TO Tar Sun
LONDON, June 16.-when Sis Charles
Parsons Invented the turbine steam en-
CINE the engineering world at once aues-
toned the efficiency Of the new invention
| which passed the tests at a considerably
higher percentage than any marine en-
CINE hitherto built. But the more recent
invention Of the Still engine gives a
brake thermal efficiency OF 80 per cent.
over its predecessors. and by means Of
governor control alone can meet any de-
mgnd UP to and over 100 per cent. over
Dad, and maintain a good efficiency at
that increased output
Frank E. D. Acland. member of the
Civil Institute OF Civil Engineers. recent
ly gave details of the invention before
the Royal Society of Arts.
The Still engine is an engine capable
OF using In It's main working cylinder
any form OF liquid or gaseous fuel hith-
trio employed: II makes use OF the re-
coverable heat which passes through
the surfaces Of the combustion cylinder,
as we'll as into the exhaust gases. for the
evaporation of steam. which steam is
expanded In the combustion cylinder IT.
self on one side OF tho main piston. the
combustion stroke acting on the other
side. 1t increases the power Of the en-
gine and reduces the consumption of the
fuel per horsepower developed.
In other words, the engine uses both
forces, the explosion OF the gas or oil
and the steam generated by the cooling
water for the production of power.
New Cooling Device.
Internal combustion engines are kept
cool by the circulation OF cold water
round their cylinders; the heat thus alb
II. L.. g.. 90
the water as II travels through the
jacket, so that the cylinder is subjected
to temperature differences and heat
stresses which are an abiding source Of
trouble and difficulty to the designer.
In the Still engine the Jacket and
cooling water form part OF the circulat-
ng system OF a steam generator. which
may be an integral part OF the engine or
external to It. The cooling water there
fore enters and leaves the Jacket at a
CONSTANT temperature. regulated by the
'ressure of steam, the cooling being
Effected by converting the water into
steam without raising its temperature
Excluding the radiation losses, which are
sept low by tagging, all the heat which
passes through the walls is thus usefully
recovered in the water as steam. The
temperature OF the cylinder wall is uni
form over the whole Of its exterior sur
face. and the heat lost to the cooling
water at each stage OF the cycle-com-
precision. combustion and expansion-is
diminished.
During compression, owing to the
walls being at steam temperature. the
incoming charge picks up heat instead
OF iosing It during the greater part Of
the stroke. an advantage Of the greatest
value to the heavy oil types OF Still en-
gines where an air charge is taken in
at the full outstroke and Is compressed
&c a pressure where its increased tenn
perature insures the certain Ignition
and combustion OF the fuel which is In
jected into It, !,
Modification in Cylinder.
To insure the maintenance Of the tenn
perature conditions some notifications
OF the cylinder have been made. In
stead of the thick iron castings used in
the majority OF internal combustion en-
gines the cylinder OF a Still engine con-
sists of an inner liner which is approxi-
mately one-third to one-fourth OF the
usual thickness; 1t is ribbed externally
SO as to add to its conducting surface
ard provide suitable passage for the
cooling water. and 1t is reinforced by an
outer hoop capable OF withstanding the
hiBHest pTessuTeo 10 De met WIN IN
working.
From a diagram OF the Still thermal
cycle exhibited at the lecture It can be
gathered that the exhaust gases at q
temperature Of 800 r. pass through a
series OF tubes in the water circulation
device and after giving up their heat
reach the exhaust at an average tenn
perature OF $50 F. This water then
flows through the cylinder jacket. thence
into the boiler from which the steam at
a pressure of 100 pounds passes to the
steam cylinder. The boiler, which Is OF
the water tube type, is fitted with fire
box and oil blast for the purpose OF rails
ing steam II necessary to. increase the
power OF the secondary piston rapidly.
The device has been tried on five DIFF
ferent engines and three show a greater
efficiency than even the four stroke
Diesel OF 14K by 26E inches. which at
$50 revolutions per minute gave a COM
parative efficiency of So. Sun engine
l6 by 80 1.-TWO stroke) running at 100
r. p. NJ. equalled IS: while one of 15.5
by 22 inches running at 320 r. =. NJ.
gave 50; and another OF the same size
has equalled II per cent Of brake Their
NAL efficiency.
Experiments are being held with the
object OF utilizing the device for rail-
road locomotives, and several engines
are now being fitted to new vessels
that will shortly be put on the trade
routaa