Improvements in the Refrigeration and Warming of Air.
Year: 1892

page_text: Date of Application, 2nd Sept., 1892
Complete Specification Left, 29th June, 1893-Accepted, 2nd Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Refrigeration and Warming of Air.
I WILLIAM DONALDSON Civil Engineer 33 South Street Thurloe Square
South Kensington do hereby declare the nature of this invention to be as
follows:-
The improvement consists first in refrigerating the air by expansive work in one
cylinder provided with piston piston rod and suitable valves and subsequently
raising its temperature above that of the free air by compression in another
cylinder likewise provided with piston piston rod and suitable valves, the piston
rods of both pistons being commected with the same crank shaft either directly
or indirectly, after the temperature of the expanded air has been raised by contact
with warmer bodies than itself before it enters the second cylinder. The tempera-
ture of the bodies with which it comes in contact need not exceed that of the free
air. The inlet ports of the compression cylinder are connected with the outlet T
ports of the expansion cylinder by air tight passages and the capacity of the com-
pression cylinder must be designed to pump the rewarmed expanded air at a rate
sufficient to prevent appreciable increase of the pressure obtained by expansion in
the first cylinder. When the refrigerated air is to be used for cooling purposes it
is drawn through pipes, placed in the space to be cooled, from the expansion
cylinder to the exhaust cylinder or through a vacuum chamber in which objects to
be cooled are placed. When the air is to be used for warming purposes the air
after being heated partly by conduction and partly by compression is either forced
through pipes placed in the space to be warmed or forced directly into the space,
which is in this way ventilated as well as warmed, by the action of the piston in the
compression cylinder in both cases. The engine may be driven by a belt passing
over a pulley attached to the crank shaft, which is connected with both cylinders
or in any suitable way.
Dated this Second day of September 1892
COMPLETE SPECIFICATION.
Improvements in the Refrigeration and Warming of Air.
1, WILLIAM DONALDSON, of 33 South Street, Thurloe Square, South Ken-
sington, in the County of Middlesex, Civil Engineer, do hereby declare the nature
of the said invention, and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :—
This invention consists of a system for first refrigerating air or gas by expansive
work from normal atmospheric pressure, and without preliminary compression,-in
one cylinder, provided with a piston rod, and suitable valves, and for afterwards
raising the temperature of the gas or air above, that of the atmosphere by applied
heat, and by compression in a second cylinder, provided with a piston, piston rod,
and suitable valves, the piston rods of both cylinders being connected to the same
crank shaft, either directly or indirectly, so that the pressure of the atmosphere
during admission and expansion may be utilized to assist the work of the second
exhaust and compression cylinder.
In my system therefore the external atmosphere is utilized in the first cylinder
as a force, during admission, and by expansion upon a partial vacuum maintained

page_text: on the other side of the first piston, by the suction or withdrawal of air by the
second exhaust cylinder, in preferably an intervening refrigerating air tight
chamber; the first atinospheric charge being cooled by such expansive working,
and delivered on the return stroke at a reduced pressure and temperature, into the
said refrigerating chamber, and thus eventually to the suction stroke of the second
exhaust cylinder.
The gas or air at reduced temperature and pressure, so withdrawn by the second
exhaust cylinder, may be raised in temperature after leaving the refrigerating
chamber by contact, through a heat conducting tube in an annular chamber, with
the fresh charge of air at normal temperature, before the latter enters the first.
expanding cylinder; or it may otherwise be artificially heated by extraneous sources
of heat, such as waste gases of combustion, exhaust steam, etc. etc., during its
passage from the expansion cylinder to the exhaust cylinder.
The exhaust gas or air from the refrigerating chamber, thus heated, is, upon the
return stroke in the second exhaust and compressing cylinder, compressed to any
required degree, but preferably only to the normal atmospheric pressure, and
thereby further heated above normal atmospheric temperature, before discharge for
warming or heating purposes, so that upon such escape into a room or chamber, it
will not further expand and so become chilled.
The degree of expansion in the first expanding cylinder, and thereby the first.
reduction of temperature, and the degree of later compression in the second com-
pression cylinder, may be regulated at will, by the adjustment of the motion of the
respective slide or inlet and delivery valves, and of their form.
And in order that my invention may be the better understood, and that the
apparatus may be clearly ascertained, by which I may, most conveniently, carry
out my invention, I now proceed to describe the same in reference to the drawings
hereto annexed, and to the figures and letters marked thereon.
Fig. 1 (Sheet 1) is a part sectional plan of my combined expansion and
compressing cylinders, connected to same crank.
Fig. 2 (Sheet 1) is an elevation of the same.
Figs. 3 and 4 (Sheet 1) are a plan and elevation respectively of the pipe
connections, to a smaller scale, between the expansion and compression cylinders,
when arranged for ventilation purposes.
Figs. 5 and 6 (Sheet 2) are an elevation and plan respectively of an intermediate.
refrigerating chamber, and pipe attachment, to the aforesaid cylinders.
Figs. 7 and 8 (Sheet 2) are a longitudinal and transverse sections, through an
end of the refrigerating chamber, showing door and internal arrangement of
freezing trollies.
Pr
A is the expansion cylinder, provided with the piston P, and the piston rod
the inlet valve V, and the outlet valve V. The valve V, opens and closes the
inlet ports i, and the valve V, the outlet ports o. B is the cylinder of the air pump,
provided with piston, piston-rod, valves, and ports, exactly like those belonging to
the cylinder A, and distinguished by the same letters.
2
The valve V, however, in the case of the cylinder B, actuates the outlet ports,.
and the valve V, the inlet ports.
The internal diameter of the cylinder B is larger than that of the cylinder A,
and must at least be of such a size, that its capacity is equal to the volume of air
discharged from the cylinder A, after this volume has been expanded without
increase of pressure by heat, received during its passage from the cylinder A to
the cylinder B.
The piston rods are connected with the arm of the crank shaft C, by means of
the slide blocks s, and the connecting rods c. The crank shaft is driven by a belt,
passing round the pulley M; the power required to drive the machine is equal to
the difference between the work done in the cylinder B, in compressing and
discharging the air and the work done in the cylinder A by the air, during the periods
of admission and expansion, plus the work required to overcome machinery friction,
and the ris inertia of the moving parts.

page_text: The valves V, which open and close the inlet ports of the expansion cylinder A,
and the outlet ports of the compression cylinder B, are actuated by the eccentrics Ei
and E, respectively, which are like to each other in every respect.
The radius of each eccentric is separated from the arm of the crank by the same
angular interval;-that of the eccentric E,, which actuates the inlet valve of the
expansion cylinder,-in advance and that of the eccentric E., which actuates the
outlet valve of the compression cylinder,-in rear of the arm of the crank shaft.
The magnitude of this angle regulates the period of admission before expansion
commences in the cylinder A, and the length of the period of exhaust in the
cylinder B, after compression ceases. E E are fixed discs, by attachment to which
the loose eccentrics can be fixed in any desired position.
The length of the valves V₁ must be equal to the sum of the widths of the ports,
and the width of the bridge, plus the length of lap, sufficient to keep both inlet
ports closed during the period of expansion in cylinder A, and both outlet ports
closed during the period of compression in cylinder B.
A valve designed to fulfill this condition for one length of admission or exhaust,
will suffice for all greater lengths of admission or exhaust, but in the case of the
cylinder A, the admission ports will not be open at the commencement of the
stroke, and in the case of the cylinder B, the exhaust ports would remain closed,
till after the proper length of compression had been exceeded.
For perfect working therefore, a special valve must be provided for each length
of admission.
The valves V, which open and close the inlet ports of the cylinder A, and the
inlet ports of the cylinder B, are actuated by the eccentrics E, and E. respectively,
which are like to each other in every respect.
The radius of each eccentric is
separated from the arm of the crank by an angle of 90°, the radius of E, behind,
and that of E, in advance, of the arm of the crank.
The valves V, have no lap and their length need not exceed the sum of the width
of the ports, plus the width of the bridge between the ports.
The outlet valve of the compression cylinder B, and its eccentric, may be exactly
alike in all respects to the valve V, and its eccentric, without effecting the
magnitude of the changes of temperature, but it would in that case take more
power to drive the machine, because the air would be forced out of the cylinder B,
against the maximum pressure during the full stroke. The compression cylinder B
instead of being provided with the same slide valves as the expansion cylinder A,
may have beat valves, like an ordinary air compressor.
2
C, and C, are the covers of the chambers of the valves V₁ and V, respectively.
The covers are provided with the flanged orifices I, for the inlet of the air, and the
flanged orifices O for the outlet of the air.
1
The inlet orifice 1 of the inlet valve chamber V₁ of the cylinder A, always
communicates directly with the free air.
The outlet orifice O from the valve chamber V, of the cylinder A, is put into
communication either with the chamber in which the substances to be cooled are
placed, or with a chamber in which its temperature is raised by waste heat from
the driving engine, or in some other suitable way, according as the object aimed
at is the refrigeration of other substances, or the provision of warm air for
ventilation.
When the air for ventilation is to be delivered without change of temperature,
the outlet O of the valve chamber V2 of the cylinder A, is connected with the
discharge pipe from the outlet port O, of the valve chamber V₁, of the cylinder B.
The inlet port I of the inlet valve chamber V,, of the cylinder B, is connected
either with the freezing chamber, or the warming chamber, when refrigeration and
warming are the objects aimed at.
When the machine is to be simply as a blowing engine for discharging the air,
without change of temperature, the inlet orifice I of the cylinder 1 is connected
directly with the external air..
Figure 3, Sheet I, shows a plan and Figure 4, Sheet I, an elevation of a suitable

page_text: arrangement of pipes for connecting the ports of the two cylinders, when the
machine is to be used for ventilation purposes. In Figure 3 m m represents the
centre line of the two cylinders and a a lines through the centres of the inlet and
outlet ports of the cylinders A and B respectively.
I is an inlet port to valve chamber V, of cylinder A, and valve chamber V, of
the cylinder B.
The pipe p, which is provided with the sluice valves S₁, conveys the air from the
outlet port of the valve chamber V2 of cylinder A, to the chamber in which the
air is to be partially heated; or when the air is to be discharged without change of
temperature, by means of the branch P, which is provided with the valve S, direct
to the outlet pipe O from the valve chamber V₁ of the cylinder B. The pipe P
which is provided with the valve S, connects the inlet ports I of the cylinders A
and B directly.
When the air has to be heated for ventilation purposes, before it enters the
cylinder B, the valve S₁ is kept open, and the valves S, and S, are closed. The
air then passes from the pipe into the heating chamber, and after passing
through the partial heating apparatus, enters the inlet pipe I of the valve
chamber V, of the cylinder B, in the directions shown by the arrows. When the
air is to be used for ventilation without change of temperature the valve S₁ is kept
closed, and the valves S, and S, are kept open.
ول
Since the warmed air is delivered at atmospheric pressure, the whole of the
heat contained by the air per unit of weight, above that contained by the air in
the space to be ventilated, is expended in raising the temperature of the latter.
If it were delivered at a higher pressure, part and in some cases the whole, of
the excess, would be expended on the act of expansion down to atmospheric
pressure, without appreciably increasing the temperature of the air into which it
was discharged.
If the expansion took place in a room hermetically closed, the work done upon
the air confined in the room would cause an equivalent rise in its temperature, but
when the air can freely escape, the increase in pressure caused by the expansion of
the compressed air is too infinitesimal to produce any effect. When the warm air
admitted is of the same pressure, it simply displaces an equal volume of air and
diffuses its heat amongst the rest,
Since the degree to which the air is warmed above the temperature of the outside
air depends upon the degree of compression, as well as on the extent of the heating
by contact with bodies, of a higher temperature than that due to expansion, after
it has been cooled by expansion, the amount of the partial reheating absolutely
necessary for sonie purposes may be attained by passing the expanded air through
a coil of pipes, of sufficient length, to admit of its temperature being raised to the
required degree, by conduction of heat from the free air, so that the machine may
be driven by power transmitted from a distance for producing sufficiently heated
air without the provision of special heating apparatus.
When the ventilating machine is driven by a heat engine, for instance, by a gas
or oil engine, the waste heat passing up the engine chimney can be used for this
purpose, and the partial reheating in this way effected without cost.
The greater the number of degrees by which the temperature of the air has to
be raised, the greater the work to be done by the engine, and therefore the greater
the quantity of waste heat that passes up the chimney.
The refrigerated air may be used in two ways for cooling and freezing
substances, (1) By passing it through a sufficient length of pipes in a chamber,
surrounded in the usual way by walls of non-conducting materials, in which
chamber the substances to be cooled or frozen are placed.
By this method the air in the chamber is cooled by contact with the metal of the
pipes, through which the refrigerated air flows from the expansion cylinder A to
the compression cylinder B. These pipes may be passed through brine or any
liquid capable of standing the cold without freezing, as an intermediate agent for
storing and transmitting the cold.

page_text: (2) By placing the substances to be cooled in an air-tight chamber, through
which the cold air flows from the expansion cylinder to the compression;
cylinder B.
For the purpose of ice-making and freezing meat &c., this last is by far, the best:
method of using the air.
The special apparatus necessary to effect this object most efficiently is illustrated:
in Figures 5, 6, 7 and 8.
Sheet II, Figure 5, is a plan of the freezing chamber F, and the pipes required
to connect it with the expansion cylinders and compression cylinders. Figure 6 is .
an elevation of the same. The chamber shown in the drawing is simply a long,
tube, preferably circular in section, provided with removable lids L, at each end.
One end of the chamber is connected with the outlet port 0 of the expansion
cylinder, and the other with the inlet pipe I of the compression cylinder. The
chamber is traversed throughout its length by a pair of iron bars of suitable
section, resting on wood blocks, which together form a pair of parallel rails on.
which wagons, conveying the substances to be frozen, run. The wagons with their.
loads are first placed at the end of the chamber, connected with the outlet pipe,
leading to the compression cylinder. This end of the chamber is raised sufficiently
above the end, connected with the inlet pipe from. the expansion cylinder. to cause
the wagons to run by gravitation to the lower end, from which they are taken after.
the cooling or freezing has been duly accomplished. Figure 7 is a longitudinal
section of part of the chamber, showing three wagons in position, and Figure 8 a
cross section, giving an end view of a wagon and its load.
7
;
In the illustration, the wagons convey water to be frozen, two buckets being
conveyed by each wagon, the lower one rivetted to the frame-work, supported by
the wheels; the upper one placed on the lower one by means of crow bars to which
it is rivetted. Sheet metal diaphragms are placed midway between the wagons,
and are provided with a central aperture sufficiently large to allow the wagons and
substances conveyed to pass through. The object of the diaphragms is to cause
the air in passing from the compartment containing one wagon to blow directly
upon the load conveyed by the wagon in the next compartment. The substances
to be frozen are thus frozen at different rates, varying with the distance of the.
wagon from the inlet of cold air, those nearest the inlet being hard frozen, before.
those close to the outlet end have had their temperature reduced to the freezing
point.
The substances nearest to the cold air inlet are to be removed as fast as they are.
frozen or cooled to the desired degree, and, after the wagons conveying the partially
frozen or cooled substances have been allowed to run to the bottom of the chamber,
loaded wagons equal in number to those taken out, are to be placed in the upper.
end of the chamber.
The lids are then to be replaced, and the cooling machine set to work.
If more than one freezing chamber is used, the engine may be kept constantly.
at work, the connection with the chamber from which the cooled substances are.
being taken, and to which fresh substances are being added, being cut off during
the operation.
The freezing chamber ought to be lined internally with a non-conducting
substance, and preferably. also.externally. In freezing apparatus the temperature
of the air, when it leaves the freezing chamber, will always be less than that of the
external air.
In order to utilise the cold air passing from the freezing chamber through the
pipe q, Figure 5, and Figure 6, to the exhaust cylinder, for cooling the air before
it enters the expansion cylinder; this pipe ought to be enclosed in a larger pipe Q,
with the annular space between them open to the air, close to the point where the
pipes leaves the freezing chamber; the other end of the pipe Q, being connected
with the inlet orifice I of the valve chamber V₁ (see Sheet I Figures 1 and 2) of
the expansion cylinder. The air entering the annular orifice is cooled as it passes
along the annular space between the two pipes. By this means a greater weight of air

page_text: at a lower temperature enters the expansion cylinder at each stroke, than when
the air enters the inlet valve chamber at the temperature of the outside air.
When the substance to be frozen is water, a part of the air, contained by the
water, is set free, by the diminution of the pressure in the freezing chamber, and
the resulting ice rendered free from air bubbles and as solid and durable as the
best natural ice. The disengaged air carries with it a considerable quantity of
water, which appears in the form of vapour. It has been found that economical
freezing of the water cannot be effectuated by the vacuum process, until this
vapour has been got rid of. When the partial vacuum is produced by simply
exhausting the air from the freezing chamber, the air is usually dried by means of
sulphuric acid. By the method described in the present Specification, the air
charged with vapour is blown out of the chamber in such a way that it cannot
interfere with the process of freezing. The whole amount of the moist air, set
free by the diminution of the pressure, is exhausted from the water at the upper
end of the chamber and is therefore expelled as fast as it is set free, and at the
temperature of the partially warmed air, so that the capacity of the air for freezing
at points nearer the lower end of the chamber, where the cold air enters, is not
interfered with by the production of vapour in this way.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1st. A system for the refrigeration and warming of gas or air, consisting of a
first expansion, effecting work from normal atmospheric pressure without preliminary
compression, for refrigeration, in one cylinder; and further a withdrawal and
heating of said expanded gas or air by external warmth and final compression to
atmospheric pressure, and to above normal temperature, in a second cylinder,
coupled to same crank as first cylinder, and externally driven, for general
refrigerating, warming, and ventilating purposes, substantially as described.
2nd. In such a system, the partial cooling of the entering air or gas at normal
atmospheric pressure by transference, by conduction, of its normal heat, to the
cooler issuing expanded air or gas, from the refrigerating chamber or expansion
cylinder, substantially as described.
3rd. In such a system, the heating of the expanded gas or air in its passage from
the expansion cylinder or refrigerating chamber, to the exhaust or compression
cylinder, by conduction of heat from the atmosphere, or from the waste gases
discharged by the prime motor apparatus, substantially as described.
4th. In such a system the arrangement of a long refrigerating chamber, by which
the cold gas or air entering at one end, passes in a continuous stream from an outlet
at the other end of the chamber, the water or moist material to be refrigerated,
being fed into the said chamber from the end nearest to the outlet, so that the
vapour arising from the said water or moist material, under reduced pressure,
passes away with the passing air or gas, as quickly as possible, to the said outlet,
substantially as described.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.