IMPROVEMENTS IN APPARATUS FOR ABSTRACTING HEAT
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by John Norman at the Office of
the Commissioners of Patents, with his Petition, on the 18th
August 1871.
I, JOHN NORMAN, of Glasgow, in the County of Lanark, North,
Britain, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN APPARATUS FOR ABSTRACTING HEAT," to be as follows,
that is to say:-
This Invention has for its object to contrive simple and convenient
apparatus for abstracting heat, and such as can be made to act efficiently
when of comparatively small size.
In carrying out the Invention the well-known process is employed
of compressing air, abstracting its heat whilst compressed, next
allowing it to expand, and using its power of abstracting heat whilst
expanding.
In one modification of the improved apparatus two cylinders are
employed, in one of which the air is compressed by means of a piston,

page_text: which is by preference of wood, of considerable depth, and packed with
cotton saturated with tallow or other suitable lubricant. A passage
leads from the compressing cylinder to the second or cooling cylinder
or chamber, and the regenerator usually employed in such apparatus
is placed in this passage. The lower portion of the cooling chamber is
by preference square, the upper part being cylindrical and fitted with a
piston, and this and the compressing piston are suitably connected to
levers worked by hand or by revolving gearing. The passage from the
compressing cylinder communicates with the cooling chamber by
passages on two sides and through perforations arranged to equalise
the action of the currents of air. The other two sides of the cooling
chamber are fitted with doorways provided with covers, which can be
easily and rapidly closed, so as to be air-tight, there being for this
purpose grooves formed round the doorways and lined with rubber for
projecting edges on the covers to bear against; or a single door on one
side may be sufficient. Inside, the chamber is fitted with shelves or
ledges to receive a number of dishes or boxes, and the water or other
substance to be cooled or frozen is put in the cooling chamber in such
dishes or boxes.
The main feature of the Invention is the placing of the substance to
be cooled or frozen in portable dishes or boxes in the place where the
expansion of the air actually takes place, instead of either employing an
intermediate current of brine to transfer the cooling action to a separate
vessel, as has been done heretofore. The compressed air may be cooled
by cold water in jacket spaces surrounding the passage from the com- :
pressing cylinder to the regenerator, and also if necessary surrounding
the compressing cylinder itself. Suitably loaded valves are fitted in
connection with the two cylinders to regulate the air inside, one in
connection with the compressing cylinder opening inwards to admit
air should the internal pressure become too low from any cause, and
the other in connection with the cooling cylinder opening outwards
to allow air to escape should the pressure become too high.
The apparatus has been described as single-acting, but it may be
made double-acting if preferred, by arranging a second cooling chamber
in communication with the other sides of the two pistons, and it may
be made principally of metal, or to a greater or less extent of earthen-

page_text: ware or other suitable non-conducting material, being in the former
case by preference covered externally with felt or other non-conducting
material.