Improvements in or Appertaining to the Heating of Air or other Fluids.
Year: 1887

page_text: Date of Application, 16th Aug., 1887
Specification Accepted, 20th Sept., 1887.
Improvements in or Appertaining to the Heating of Air or other
Fluids.
I, JAMES TENNENT, of Callander Cottage, Grangemouth, in the County of Stirling,
Student, do hereby declare the nature of this invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the following
statement:
The object of this invention is to provide a means whereby heat may be readily
communicated from one fluid body to another by the direct contact of the said bodies
with each other.
The invention consists mainly in placing two (or more) fluid bodies in a suitable
chamber or generator one above the other, (the lower one, from which the heat is
transmitted, being of a comparatively greater specific gravity than the upper one
which receives the heat,) and applying to the bottom of the generator a fire or other
source of heat.
The two bodies are placed within the generator in contact with each other. They
may both be in the solid state before heat is applied and afterwards become liquified
under the influence of said heat. Or before commencing operations they may be both
liquids or both gases, or one may be solid and the other liquid or gaseous, or one
liquid and the other gaseous, provided only that their specific gravity be different, and
that the denser body be at the bottom of the generator.
When the superincumbent body is gaseous, or becomes so whilst the generator is in
operation there is imparted to it, by reason of the heat, a certain amount of molecular
repulsion which causes its pressure, and therefore the pressure in the generator, to be
increased.
As an illustration I will describe the process as applied to water and air, this
combination yielding the most useful results for general purposes.
The generator may be of any convenient form or substance which is strong enough
to withstand the pressure of the contained fluids. One form is shown in the drawings,
in which,
Figure 1 is a longitudinal section the upper closed end being broken away.
Figures 2 and 3 are transverse sections on x, x, Figure 1, looking upwards.

page_text: The generator A, which may be of any convenient shape, is filled with water to the
extent of about one fourth (more or less) of its capacity, and all openings in it are
then closed, and made air-tight, so as completely to prevent escapement of the super-
incumbent air during the process of heating. Heat, from some convenient source, is
now applied below the generator.
The volume of air thus confined above the surface of the water increases both in heat
and in pressure simultaneously with the heat of the water, while the confined air so acts as
to prevent the evolution of superficial steam by ebullition or other wise, on the surface of the
water, with the result that the aforesaid volume of air, while acquiring both pressure
and heat from the water, remains in other respects as intact as it was before the heat
had been applied. The volume of air thus heated may afterwards be utilised either for
motive power or otherwise, and it may be taken directly from the generator itself, or
through an intermediate air-receptacle or chamber connected with the generator in
the usual way.
When the generator is to be employed for purposes in which the pressure of its
entire volume of air requires to be utilised or exhausted suddenly, a diaphragm B
provided with a slide or other valve C is necessary to cut off communication with
the water before releasing it of the superincumbent air-pressure. This is necessary in
order to prevent the sudden conversion of the water into steam or aqueous vapour.
If, for any purpose, such partial admixture of steam with the air would not be prejudicial,
the steam so generated would serve to augment the impetus of the volume of air when
discharged.
The fixed diaphragm B is located immediately above the water-space, and is of
sufficient strength to resist or support the highest pressure at which the generator is
designed to be used, the said fixed diaphragm having a number of holes or other
perforations therein, the number varying with the size of the diaphragm. Immediately
underneath (or above) the said fixed diaphragm is a smaller sliding diaphragm C
acting as a slide-valve, which is capable of being moved forward and backward on a
screwed rod D which may be turned by a handle d or otherwise. The said rod is
supported in bearings a on each side of the generator, and passes through the screwed
lugs c attached to each end of the said sliding diaphragm. The lower surface of the
one diaphragm is throughout in as close contact with the upper surface of the other
as to resist, when closed as hereafter described, the pressure below it, due to the
undeveloped steam energy then latent in the water. The said sliding diaphragm C
contains a series of holes c¹ equal in number to the holes in the diaphragm B. Their
relative position is such that when the sliding diaphragm C is moved against one side
of the generator (as in Figure 2) the holes therein shall exactly face, or be opposite to
the holes in the fixed diaphragm B, and thus form an open communication for the heat
to pass into the air by contact with the water. When the required pressure or heat is
obtained, by turning the handle d of the screwed rod in the proper direction, the
sliding diaphragm is moved against the opposite side of the generator, which action
places the holes of the one diaphragm directly opposite to the solid parts of the other,
and cuts off the communication between the upper and lower parts of the generator.
When more than two fluids are subjected to the process conjointly, the number of
the divisional diaphragms may be increased accordingly, and when the communication
is to be cut off for a lengthened period, care should be taken to reduce or regulate the
heat applied to the generator externally, so that the diaphragm when closed, may not
be unduly strained by the accumulating pressure of the fluid underneath.
When a gas is used instead of air, the process is similar, but, if desirable to prevent
mixture of the gas with the internal superincumbent air, this air may be exhausted
before putting gas into the generator.
In the case of either common air, or other gases being treated in the foregoing
special manner, the pressure to which any of these may be forced into the exhausted
air space in the generator, previous to the application of heat thereto, may be made to
vary more or less than the ordinary pressure of the free atmosphere."
For the purpose of filling the air space in the generator with gas or air before .com-
mencing operations, and for the subsequent renewal of its contents at intervals as

page_text: required, an ordinary air compressor may be employed, operated either by hand or
otherwise.
By introducing water or a similar fluid medium into the lower end of the generator,
the material of the generator itself is preserved against the excessive deterioration to
which that portion of a generator directly affected is liable when heat is applied to it
with no water, or similar medium introduced.
Having now particularly described and ascertained the nature of the said invention,
and in what manner the same is to be performed, I declare that what I claim is :-
1. The process of transmitting heat through one or more fluid bodies to another of
less specific gravity, and in direct contact therewith by confining, in a closed vessel or
generator heated at its lower end, two or more of the said fluid bodies arranged one
above the other according to their relative specific gravity, the denser of any two of
them being nearest to the external source of heat, and in direct contact with the one
above it, substantially as and for the purpose described.
2. The means by which heat may be transmitted and expansive force imparted to a
gaseous body through one or more fluid bodies, namely, by confining the said gaseous
body with one or more fluid bodies of less specific gravity in a closed vessel or generator,
and by applying heat externally to that end of the generator which is in contact with
the contained body having the greatest specific gravity, substantially as and for the
purpose described.
3. In a closed vessel or generator for heating air or other gaseous bodies, a quantity
of water or other fluid introduced into the lower end thereof, whereby the deteriorating
action of the heat and the contained gaseous bodies on the generator is impeded.
4. In a closed vessel or generator such as A, for transmitting heat through one or
more fluid bodies in direct contact with each other, a fixed perforated diaphragm such
as B placed on the plane of contact between any two of the aforesaid bodies, in con-
junction with a sliding similarly perforated diaphragm such as C, whereby the contact
between any two of the said bodies may be broken at will.
Dated this 15th day of August 1887.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Agents for the Applicant.