SS IIMMINMILII

   

eTHS,
A STUDY OF MECHANICAL REFRIGERATION
and test run on M.A. C. Dairy

REFRIGERATION PLANT.

A THESIS SUBMITTED TO
The Faculty of
MICHIGAN AGRICULTURAL COLLEGE

my

BY ‘

A
5 x
r

\

M. Be Kichelberger, D. F. Jones, A. L. Alderman
Candidates for The Degree of

BACHELOR OF SCIENCE.

June 1916.
HISTORICAL.
THE DEVELOPEMENT OF COLD STORAGE.

Mother earth as a source of available refrigera-
tion, is without doubt a pioneer. In the temperate zcne at a
depth of a few feet below the surface, a fairly uniform tempera-
ture of about 50° to 60°F, is to be obtained at all seasons. In
some cases a much lower temperature is obtained. The same princi-
ple is true in any climate, the earth acting as an equalizer be-
tween extremes of temperature, if such exist. Caves in the rock,
of natural formation, are in existance, in which ice remains the
year around, and many caves are used for the keeping of perish-
able goods. The Ruskin Co-operative Colony, located at Ruskin,
Tennessee, has a fine large cave on its property which is utiliz-
ed as a cold storage warehouse. The even temperature, dryness
and purity of the atmosphere to be met with in scme caves are
quite remarkable, owing no doubt to the absorptive and purifying
Qualities of the rock and earth, as well as to the low tempera-
ture obtainable.

CELLARS.

Cellars are practically caves built by the hand
of man, and if well and properly built are equally good for the
purpose of retarding decomposition in perishable goods. A journ-
ey through the Western states reveals many farmers who are poss-
essors of "*root-cellars" considered the first necessity of succ-
eseful farming, the new settler building his cellar at the same
time as his log house. A rnot~-cellar is used partly as a protec-

tion against frost, but it also enables the owner to keep his
vegetables in Fair condition during the warm weather of spring

35060
CELLARS. (CONDT).
and summer months. The use of cellars for long keeping of dairy
products is familiar to all. Many of us can recollect how our
Mothers put down butter in June and kept it until the next win-
ter, and perhaps it will be claimed by some, that the butter was
as good in Janurary as when it was put down. It is not as good,
far from it. If you think it was, try the experiment to-day and
you will see how it will taste ani how much it will sell for in
Janurary in competition with the same butter stored in a modern
freezer. The butter made years ago was not better either. No
better butter was ever made than we are producing to-day. In
short, cellars were considered good because they had no competi-
tion- they were the best before the advent of improved means of
cooling. Cellars are still of value for the temporary safe keep-
ing of goods from day to day, as for the storage of goods requir-
ing only a comparatively low temperature, but with a good refri-
gerator in the house, the chief duty of a cellar, nowadays, is to
contain the furnace, and as a storage for coal and other nonperish-
able household necessities.

ICE.

The use of ice as a refrigerant during the summer
months is a comparatively modern innovation, and not until the
nineteenth century did the ice trade reach anything like scptema-
tic developement. The possibility of securing a quantity of ice
aquring cold weather and keeping it for use during the heated term
seems not to have occured to the people of revolutionary times.

About 1805 the first large ice house for the storage of natural ice
ICE. (CONDT).
was built, and with a constantly increasing growth, the business
increased to immense proportions in 1860 to 1870. The amount
harvested is now much larger than at that time and constantly
increasing, but the business is now divided between natural ice
and that made by Mechanical means.

Mechanical refrigeration in which the storage
rooms are cooled by frozen surfaces, usually in the form of brine
Or ammonia pipes, was much superior to ice refrigeration, in that
the temperature could be controlled more readily and held at any °
point desired and that a drier atmosphere was produced. Ice is
at present and will probably always remain a very useful and cor-
rect medium of refrigeration, especially for the smaller rooms
and certain purposes.

THE PRINCIPAL USES OF REFRIGERATION ARE AS FOLLOWS:

(1) Prevent premature decay of perishable products.

(2) Lengthen the period of consumption and thus
greatly increase production.

(3) Enable the owner to market his products at will.

(4) Make possible transportation in good cundition
from point of production to point of consumption, irrespective of
distance. (5) Cooling the air of buildings for the comfort of
the inhabitants.(6) Prevent the destroying of goods by insects, etc.

(7) Manufacture ice cream.

(8) Manufacture ice.
4.

First: Without refrigeration there would be much actual
waste from decomrosition before it would be rossible to place
perishable food products in the possesion of the consumers. The
immense fruit trade of the Pacific coast would never have been
developed witout the assistance of refrigeration, nor could the
surplus meat products of the southern hemishpere have been brought
half way around the globe to relieve the shortage in thickly set-
tled England without its aid. Without the aid of refrigeration
to create a constant market, the production of meats, eges, fruits
and other food products would be greatly curtailed.

Second: In many classes of produce the ordjinary season of
consumption wag formerly limited to the immediate period of pro-
duction, or but briefly beyond. Now nearly all fruits may be pur-
chased at any season of the year and dairy and other products are
for sale in good cordition and at reasonable prices the year aroun.

Third: Instead of being obliged to sell perishable goods,
when produced or purchased, at any price obtainable, the owner can
now put away in cold storage a portion or all of his products to
await a suitable time for selling. Thies not only results in a bet-
ter average price to the producer, but places perishable food stuffs
at the command of the consumer at a reasonable price at all times
and greatly extends the period of profitable trading in such products.

Fourth: The certainty and perfection with which food pro-
ducts may be conveyed from the place of production to the large cen-
ters of population where they are to be consumed is one of the tri-
umphs of refrigeration; yet the refrigerator car service is only in
its infancy as far as perfection of results is coneerned. It is

safe to say that our immense Pacific coast fruit trade could not ex-
ist without it.
D-

Cold storage is a benefit to all mankind in that it allows
Of a greater variety of food during all seasons of the year.
Some of the advantages of preservation by refrigeration are:

(1) It has been proved the most effective as a preservation,
surpassing in efficiency, salting, boric compounds, or any other
practical method.

(3) It adds nothing and subtracts nothing from the article
preserved, not even the water, and in no material sense alters its
qQuality.

(3) It causes no change of appearance or taste, but leaves
the meat or other substance substantially in its original condi-
tion, while it renders it neither less nutritious nor less diges-
tible, which cannot be said of some other methods in common use.

Fifth: Should artificial cooling of buildings become at
all common, considerable care must be excercised by those enter-
ing such buildings from a considerably higher outside temperature
if "“colds® or more serious forms of bedily disorders are to be

avaided.
Air cooling has already assumed considerable commercial

importance in several industries, notably in the manufacture of
chocolate and in the operation of blast furnaces.

In order to determine the capacity of ths refrigerating
machinery necessary to maintain a given room or building at a
predetermined temperature and relative humidity, under certain
prescribed conditions of outside temperature and humidity, the
engineer must not only be able to predict with considerable accur-
acy the amount of heat that will enter the room or building in

Question from the outside, under the conditions assumed, but he
6.
must also make proper allowance for the amount of heat generated
within the room or building, both by its human occupants and the
illuminants which are used.

Sixth:The placing of furs and such fabrics as carpets,
tapestries, clothing, woolens, etc., in cold storage in order to
protect them against the inroads of those insects which prey up-
on them during certain portions of the year, is now generally re-
cognized as the most satisfactory method of dealing with this im-
portant problem.

It was found that any temperature below 45° F was suffi-
clent to keep the larvae of both the moth and bettle from doing
any damage to furs or fabrics.

Seventh: The wholesale manufactures of ice cream which
was begun in this country by Fussell in the early fifties, reach-
ed an estimated yearly output of 113,000,000 gallons, valued at
nearly $100,000,000 during the year 1911.

Mechanical refrigeration is at present made use of in
the ice cream industry in one of three years.

1 st. It may be used only for freezing, hardening and
storing the ice cream.

end. It may be employed simply for the manufacture of
ice, the freezing, hardening, and storing of the ice cream then
‘being accomplished by the old ice and salt method, or by the
use of brine refrigerated by means of ice.

Srd. It may be used directly in the manufacture and
storage of the ice cream and, in addition in the production of

the ice required in the shipment of the finished product.
7.
ICE MANUFACTURE.

Eighth:Next in importance to the direct utilization of
refrigeration for the cooling of perishable products is that of
artificial ice making. There are a number of systems which may
in the future modify present methods, practically all the ice
produced today is made either by the can or plate system. the
can system is the more common of the two, being cheaper in first
cost and requiring less attention in manipulation. The plate
system, however, has the advantage of being more economical in
the end and of giving a clearer ice.

The can system:

The apparatus used consists of a larger ree-
tancular wood or iron tank containing the expansion coils or pipes.
Galvanized-iron cans are placed between the rows of expansion coils.
These cans are filled with distilled water and when the brine is
chilled below the freezing point, the water in the cans freezes.
If the temperature of the brine is not allowed to fall below 25°
and ordinary well-water is used in the cans, the ice produced will
be comparatively clear on the outside and rather snowy in the cen-
ter. If, however, the brine temperature is allowed to fall to
about 15°, the ice will be ebtirely opaque.

To get good clear ice, distilled water is used. fThe
white appearance in ice made from non-distilled water is due to
minute air-bubbles which are held in suspension in the water and
frozen in the ice, forming a sort of snow. In case of distilled

water, this air is eliminated by boiling and subsequent evapora-

tion.
 
.8.
In the ordinary ice factory, the distilled water is usual-
ly made by condemsing the exhaust steam of the engine operating
the compressor if? case of a compression plant, or by cooling the
condensed steam that leaves the generator, still,or retort of the
absorption plant. Usually this does not furnish enough condensate
for the amount of ice made. It is therefore necessary to draw

from the boilers.

-Plate system of manufacturing ice:

Mechanically, a plate plant is so constructed that the raw
undistilled water to be frozen is brought in contract with plates
of sheet metal bolted to either brine or ijirect expansion coils,
in which a sufficiently low temperature is maintained to bring
about the necessary heat transfer from the water at 32° . These
plates which are not usually less than 14 feet long by 10 feet
deep are submerged in the plate tank. The refrigerating agent is
allowed to flow through the coils until ice has accumulated to a
thickness of 13 to 14 inches on the plate. The cold brine or ammon-
ia ig then shut off and hot brine or ammonia is circulated through
the coils until the ice is loosened from the plate and floats free
in the water. Chains are then fished around the cake and it is
hoisted from the tank by a traveling crane and carried to a tilting
table, where it is carefully deposited to avoid breaking. Here it

is sawed into cakes.
INSULATION.
The vital Importance of Insulation:

For a good many centuries men have known better than
to store wine in leaky vessels. To-day no one allows steam, that
ought to be turning machinery, to escape from broken pipes. Nor
ies electric power permitted to go to waste by failure to insulate
properly the supports on which the wires are carried. Yet many
men pump refrigeration into rooms day after day, making little or
no intelligent effort to prevent the heat from constantly leaking
back.

Ita importance is frequently overlooked. The reason
for this neglect may be sought in several quarters. Heat is a
very commonplace thing. We experience its effect every hour that
passes. There does not seem to be anything particularly wonderful
about it. But if we stop to consider, we find ourselves face to
face with the fact that all known forms of energy, it is the most
powerful and allpervadinz. We can shut out the light; certain gub-
stances are impervious even to X -rays, but as for heat, nothing
will completely stop its passage.

No one needs to be told the part of refrigerating
machine is to play in keeping a room cooled to proper temperature.
One can see the wheels go round and watch the measured stroke of
the compressor. As for the insulating material, what good does
it do? So the average man is apt to reason. Get anything that wi.l
fill up space fairly well, stuff the walls, floors and ceilings, and
let it go at that. Insulation does not show; it will all be covered
up anyway. Why bother much about it, or spend time and money in de-

Signing and installing it?
10.

Good insulation is true economy.
At this point, by following this natural but erroneous reasoning,
many plant owners make their first big mistake, the results of
which follow hard on their trzil for many a year, revealing them-
selves in the form of increased operating expense, rapid deprecia-
tion of machinery and insulation repairs. The fact is that the in-
sulation of any cold storage room is just as important as the refri-
gerating rachinery. Three fourths of the work of the machine in
the average plant is done to remove the heat that leaks in through
the walls, floors and ceilings; but one-fourth goes to cool the
goods in storage.

If you use ice, seventy-five out of every one hundred
Oounds put in your coolers is melted by the heat that works its
way in from all sides. This loss cannot be prevented entirely,
because no material is heat-proof. It is possible, though, to
cut it down to a point, neither above which nor *elow which you
can profitably afford to go. If any plant is to operate ona
truly economical basis, it must be protected against heat to a
point where the saving in operating expense, effected by addition-
al insulation, would not be offset by the extra cost involved.

As a well known refrigerating engineer has said: "Insula-
tion should be considered in the light of a permanent investment,
just as builaings and equipment, the returns of which should be
based on the savings effected by the lower orerating cost. It is
& great deal cheaper to prevent heat from entering a building than

to remove it by means of refrigeration".

The word insulation is derived from a Latin word meaning

ifeland. The significance therefore, of the definition of insulate,
 
ll.

as given in the dictionary will be readily grasped. " To place
in a detached situation having no communication with surrounding
objects". In insulating a cold storage room, what the engineer
tries to do, is to make it an island in the ocean of heat.

Heat, though, has several ways of getting about. It
can pass through space on the ether waves without appreciably
heating the air. Stand in front of a stove and the truth of this
assertion is self-evident. Or, perhaps, the sensation of warmth
that one feels in bright sunlight on a cool day is a better illus-
tration of the radiation of heat, as this method of its transference
is called.

When the problem of insulating a cold storage room is
under consideration, however, the other two ways that heat moves
are of more importance. By conduction is meant the transference
of heat waves from one molecule or particle of matter to another.
For instance, put one end of a poker in the fire and soon the other
end will get hot, although far removed from the source of heat.
This is exactly the process that goes on in the walls of a cold stor-
age rooms. The outisde is heated by the sun's rays as the warm air.
The Molecules on the surface are first set in motion. Gradually the
wibratory movement spreads and coes deeper and deeper into the wall.
When the Woleculag excitement gets into the insulation, it travels
forward less rapidly. The process of the heat is impeded, just as
piling along the water front breake the force of the incoming waves.
Still, same of the heat eventually passes through, the amount depend-
ing upon the efficiency of the insulation. Slowly but surely the

temperature of the room rises, unless refrigeration is continuously

applied to offeet the heat leakage.
 

so’

 
12.

The heat conductivity of dense substances-metals, whose
@olecules are heavy and close together- is very high; the conducti-
vity of lighter material, such as wood, is less, while that of the
gases is extremely low. Hence, air, the most available gas, is
the most efficient insulator that can be Had, if a vocumn, impract-
icable on a large scale, be excepted. But the problem is to confine
it so that it cannot circulate; for the transmission of heat isa also
effected by another means called convection , or in other words, the
carrying of heat from one point or object to another by means of

some outside agent, such as air or water, or any gas or fluid. Con-
vection is the principal utilized in the ordinary house furnace. The
outside air is drawn in through a duct, is heated, and risers through
Pipes to the various rooms, its place being taken by a new supply of
cold, heavy air, which passes through the same process.

On a miniature scale, this is exactly what takes place in
every form of insulation. The side next to the outer air is warmer
than the side next to thr cold room. The air against the outer wall
of each air space in the insulation becomes heated and riseks, its
place being taken by the cold air from the other side. As this be-
comes warm, it forces its way upward; the other part, having gradually
cooled, drops to ‘the bottom, and thus a constant circulation is set
up inside the air space itself. This movement tends to equalize the
temperature on both sides of the air space and will continue as long
aa there is any difference in temperature. The fewer the air spaces,
the more rapidly will heat pass from one side of insulation to the
other. Therfore, the best insulation is that which embodies the great-
est number of the smallest possible air spaces, for the smaller tne
air spaces the less extensive will be of effect of the circulation of

the air confined therein. The rrobiem is then, so0 far as the nonconuu?tio
 

 

13.

of heat is concerned, to find some material which contains a large
amount of entrapped air absolutely confined in minute particles.

To meet the demands of modern cold storage construction,
however, suitable insulating material has to rosses a number of
other qualifications besides being an excellant nonconductor of
heat. The plant owner demands that the insulation he installs
shall retain its efficiency indefinitely. This is merely another
way of saying that it must not absorb moisture, for water is a
good conductor of heat, and any insulating material that will
absorb it, will in a short time become worthless.

Sanitaticn requires that all insulating material shall
keep free from rot, mold and offensive oders, and be varmin and
germ proof. The delicacy of certain food stuffe, such as milk,
cream, butter and eggs, requires that the insulation shall be
Odorless, as otherwise there is danger of tante.

Economical building calls for the use of an insulation
that will occupy the least possible room and leave the maximum
anount of storage space. Expediency demands that the material
be easily erected and have ample structural etrength. The fire
underwriters insist on the fire risk being reduced, as far as
possibie, by the installation of some material which will not
Only be slow burning, but will leave no flues in the walls to
assist in the spreading of fire once under way. Finally the
material must be reasonable in coat.

It next confronts one to supply materials which will
meet these requirements.

Such materials as chopped straw, and hay, dried grass,
iJeaves, chaff and various grains have been used especially in
14.

rural districts due to then cheapness and availibility.

They are used very little for cold storage due, to
their short life. Sawiust and shavings are somewhat longer lived
then the before mentioned materials. Mineral wool, sheet cork,
hair felt, quilt insulators, and insulating papers, are most
commonly used fcr cold storage work.

Any one, or a combination of the above named in-
sulating materials may be used.

In its broader sense refrigeration may be defined
as the process of cooling, but since cold is but the absence of
heat, as dark is the absence of light, refrigeration may be more
acurately defined as the process of extracting heat. The best
way to abstract heat from any substance is by placing near it an-
other substance materially lower in temperature, under which con-
dition the tendency is for the heat to flow from the substance of
the higher temperature to that of the lower- just as water flows
from a higher to a lower level. The result being that the colder
substance is heated while the hotter is refrigerated.

Refrigerating systema may be divided into two groups:
Those producing cold by more or less chemical action or chemical
Systems, and those producing cold by the evaporation of a compress-
ed gas or mechanical system. Chemical systems are used only oc-
Casionally in commercial work, but are frequently found in emall
sized plants for domestic purposes. Low first cost and the conven-
iences of handling are the principal advantages. The simple mel-
ting of ice is purely mechanical while mixing the ice with salt,
sodium chloride, ammonium, chloride and etc. to produce lower tem-

Feratures is a chemical process. Many different combinations of
wt
15.
ingredients are used in mixtures to produce cold or maintain low
temperatures in etorage rooms while repairs are being made upon
the regular machinery. The chemical methods of cooling are so
Simple that there is no cause for further discussion. Mechanical
systems include the practical commercial methods of refrigeration.
The systems now in use are, the vacuum system, the cold air systen,
the compressor system, and the absorption system.

The Vacuum System:

The vacuum machine employs water vapor as the
refrigerating fluid. From the fact that water vapor in order to
have a low temp. must have a very low tension, arises the name
"Vacuum" machine.

The operation of the vacuum machine is precise-
ly similar to that of an ammonia compressor machine. The vacuum
is formed by a pump, which withdraws the vapor from the refrigera-
tor, where the pressure is about one pound per square inch or less,
and compresses it into a condenser at a pressure of about 1.5 pounds.
The evaporation of a part of the water in the refrigerator withdraws
enough heat from the remainder to turn it to ice: or if the refrig-
erator contains brine, the heat absorbed by evaroration lowers the
temperature of the brine.

In a vacuum machine of this type the vapor cylin
der must have a capacity of about 150 times that of an ammonia com
pression machine for the same tonage. The number of gallcne of con-
densing water per ton of ice melting capacity, assuming a range of

30° F in the condensing water,is 340. The ice melting capacity per
16.
pound of coal, assuming three rounds of coal per hour fer horse-
power, is about 25 pounds.

It is evident that the enormous size of @& vacuum mach-
ine of this type ruts it out of competition with other refrigera-
ting-machines.

In another form of ¥Yacuum machine,the use of the large
compressor in avoided by the use of sulphuric acid as an absorbent.
The sulphuric acid maintainin- a vacuum by absorbing the vapor from

&@ spray and thus lowering the temperature of the remainder of the
epray. The principal objection to the use of sulphuric acid is th:t
the acid is an inconvenient liquid to handle. It must be handled

in lead or lead lined ripes.

COLD AIR SYSTEM.
The cold air system is used primarily on ship board.

The cycle has four parts, compression in one of the cylinders of
the compressor, cooling in the air cooler by giving off heat to
the cold water thus removing the heat of compreseion, exransion
in the second cylinder of the compressor thus cooling the air, and
refrigeration in the cold storage room where the heat lost during
expansion is regained from the articles in cold storage.

set. Since the specific heat of air is .2377 and that of
Ammonia.,is about .0o4, and as air is liquified at - 190° F at atmos-
phere pressure or at room temperature this would require a press-
ure of about 3000 lbs. per square inch, which would be very impract-

ical. Therfcre the latent heat ofevaporation cannot be taken advan-

tage of and used with the air machines as in case of the ammonia

machines where at atmosphere pressure the ammonia liquifies at
17.

~ 28.5° F, or at room temperature the pressure required to li-
Quify the gas is 125 pounds rer square inch. The cylinder of
the air machine in practice is about twenty times the size of
that of an ammcni2 machine for the same tonnage. This causes
the cold air machines tc be much less efficient, due to clear-
ence, heating of the compression cylinder, snow in the expan-
sion cylinder, due to moisture in the air, and greater fric-
tion losses.

A Comparison between the two systems:

The absorption System is very similar to the com-
pression system in that they both use a refrigerant, that is,
@ liquid having a comparatively low boiling point. Perhaps
the most common refrigerant is anhydrous ammonia which boile
at atmospher® pressure, at 38.5 F below zero and in doing so
absorbs as latent heat 573 B.t.u. Sulphur dioxid (SOs) is used
to a less extent; it boile at 14°F below zero under atmosphere
pressure with a latent heat of 162 B.t.u. Carbon dioxide (Cfo)
is sometimes used, it boils at 30°F below zero under a press-
ure of 186 pounds fer square inch absolute with a latent heat
of 140 B.t.u.

Pictet Fluid was founded by Prof. Pictet, a Swiss
physicist who found that a mixture of 27% of sulphur dioxide
and 3% of carbon dioxide, commonly known as carbonic acid gas
gives a boiling point of 14°F lower than sulphur dioxide. Its
latent heat has never been closely determined but is very near-
ly the same as pure sulphur dioxide.

The choice of a universal refrigerant can scarcely
18.

be made because of the varying conditions of individual rlants.
The principal difficulty with the use of (SOs) sulphur dioxide
ie the fact that any water uniting with it by leakage immediate-
ly froduces sulphorous acid with ite conoding action upon all
the iron surfaces of the system. The objection to the use of
carbon dioxide are, first, ite comparatively low latent heat,
and second, the high pressure to which all parts of the appara-
tus and piping are subjected. Pressures of from 3°00 to 900 lbs.
per square inch are very common. Perhaps the worst charge that
can be made against ammonia as a refrigerant is that it is high-
ly poisonous and corodee metals, particularly copper and copper
&lloys. However, the high latent heat of ammonia, together with
the fact that its pressure range is neither so high as with car-
bon dioxide, nor so low as with sulfhur dioxide, perhaps the chief
reason for the very general use of ammonia as the commercial refri-
gerant in compression systems; while its great affinity for,and
solubility in water, are what makes the absorrtion system a rossi-
bility.

THE ABSORFTION SYSTEM.

The great affinity of ammonia gas for water and its
solubility therein, are “hat makes the absorption system a possi-
bility and give it the name as well. At atmospheric pressure and
50° F temperature one volume of water will absorb about 900 volum-
es of ammonia gas. At atmospheric pressure and 100° F temperature
one volume of water will absorb only about one half as much of the
ammonia gas, or 450 volumes. It is then quite evident that a strean

of water may be used as a conveyor of ammonia gas from one place
or condition to another, say from a condition of low temperature
19.

and pressure where the absorbing stream of water would be cool,

to a condition of hich temperature and pressure where the gas
would be liberated by simply heating the water. It will be seen
that the gas has been transferred as a liquid without a compressor
Or any compressive action, by pumping a stream of water of approx-
imately one fourth hundred and fiftieth of the vol. of the gas
traneferred. This is the principal by which the ammonia gas is
conveyed from a relatively low temperature and pressure of the
evaporator to the high temperature and pressure at the entrance

of the condenser, in the absorption system.

The absorption system, when closely compared in prin-
cipal of operation to the compression system differs, dtffere
only in one respect, that being, the absorption system replaces
the gas compressor by a strong and weak liquor cycle.

The typical American absorption machine consists of
the following parts: a generator, an analyzer, an exchanger, a
rectifier, a condenser, a receiver, an absorber, and an ammonia
pump. The operation is as follows: the generator contaings a
solution of strong ammonia liquor in which the steam coils are
immersed. The ammonia in solution, having a lower boiling point
than the water, is practically vaporized by the heat from the
steam coils leaving a weak solution of ammonia. The gas thus
liberated,passes thru the analyzer to the rectifier. Watever
water vapor may have been carried along with the ammonia-gas is
condensed here and drips back into the generator.

From the rectifier coils the gas passes into the con-

denser, is condensed, drains, and is collected in the receiver,
10
from which it is expanded into the cooler or refrigerator coils.
The gas from the cooler fasses to the absorber and there meets
the inccming weak-liquor from the eenerator, and is absorbed,
forming strong liquor.

This strong liquor is pumped thru the exchanger into
the top of the analyzer and runs down over its pans to the gen-
erator.

It is desirable to have the atrong reach the genera-
tor as hot, and the weak liquor reach the absorber as cool, as
Fossible; The exchanger t§ interposed between the generator and
absorber in order that the weak and strong liquors may interchange
their heat. The pumps used may be of the direct-acting or gear-
driven type.

THE COMPRESSION SYSTEM.

Compression machinery may work well with the use of
any one of the following refrigerants: sulphur dioxide, ammonia,
carbon dioxide, or Pictet fluid if the proper temperature and
pressures are observed and maintained. The common refrigerator
for this type is, however, anhydrous ammonia as it presents phy-
sical properties which make it a favorite as a frigerant.

To follow the closed cycle of the ammonia, start with
a change being compressed in the cylinder of the compressor.
From this it is conveyed by pipe to the condenser which, being
See /WSCAT
cooled by water, abstracts the latent heat of the refrigerant,
ie conveyed to the expansion valve thru which it expands into the
evaporator or brine cooler. In changing from a liquid to & gas

in the evaporator it absorbes from the brine an amount of heat
Sl.
equivalent to the heat of vaporization of the ammcnia. Upon
leaving the evaporator the refrigerant is again ready for the
Cylinder of the compressor, thus completing the cycle.

METEOD.
The object of this test was to determine the €apacity,
M.A.C OMA
efficiency and power input of the,plant under running condition.
In order to take the temperature readings in the water

and ammonia pipes it was necessary to place cast iron thermon-
eter wells in the following places:
t AMMONIA TEMPERATURES

(1) On inlet pipe to both hardening and cooling rooms
after passing thru the expansion valve.

(2) Outlets to both rooms.

(3) On SUCTION and discharge pipes of compressor.

(4) Between receiver and expansion valves.
sa ( } Water

On :wtlet cooling water pipe.

// On outlet to condensing water and jacket water.
(/ These thermometers, wells were placed on the pipes and
packed with plaster of paris.
Alcohol was used in themfor low temperatured and machine
oil for those on ripes of ordinary temperatures.
Measurements of weight of ammonia and water.
AMMONIA.
As there was no way of measuring the flow of ammonia direct-

ly the volume passed was found by the volume of the compressor as-

suming a volumetric efficiency of 75%.
22

WATER.

By rearranging the water piping system the jacket and
condenser cooling water was collected, each in a separate tank
holding a known weight. Knowing the weight of water and the
temperature change the B.T.U. abstracted by the cooling water was
found.

Brake Test on Motor.

While the plant was not in operaticn a special cast
iron pulley with rim inside for holding water, was placed on the
motor.

MOTOR-PEST .

A prong brake consisting of a rectanglar frame, and a
rope which was wrapped around the pulley to absorb the power. This
frame was placed on platform scales which rested upon a platform
under the motor pulley.

Readings were taken as per sheet No S4/

Measurements were taken of both the pulleys in order to
determine slippage and of the test pulley on the motor to find the

length of the lever arm.

The plant consisted of the following apparatus:
One York vertioal single acting double cylinder enclosing compressor,
six inch bore and six inch stroke. The machine is belt driven, and
has a rated capacity of six tons of ice in 24 hours.

One ammonia condenser of York counter current double pipe
type, ammonia pipes 1-1/4 dia. The stand is about ten feet long and
ten pipes hich.

One ammonia receiver and oil separator.
450 feet of

23.

1-1/4 extra heavy continuous welded coils for ice cream

hardening room.
750 feet 1-1/4 extra heavy continuous welded coils for cooling milk

roome

Two pressure gauges, to indicate the sucticn and discharge pressures.

One Allis Chalmers electric motor,

800 R.P.M.
Brine holds

direct current, 220 volts, 58 amrs.

No3K/196H belted to compressor.

in both h=ardenirg an milk room to hold the temperature

while the machine is not in use.

Oil Separator.

Expansion Valves.

The following auxiliary apparatus was used.

> low reading thermometers.

© thermometers reading between 0 and 100 degrees.
Two large tanks for measuring the cooling water.
1 speed indicator.

1 voltmeter.

‘ l prony brake and scales.
2 lengths of hose, about 25 feet each.
1 O.I. Pulley

1 Pr.

scales

10 Thermometer Wells
1 Bristol Recorder

In conducting this test the following observations were taken every

30 min.

Temperature
Temperature
Pressure of

8 8
Temperature

Temperature
®:
w

Temperature

Ammonia:

of ammonia entering compressor.

of ammonia leaving compressor.

ammonia gas entering compressor.
" " leaving "

of liquid ammonia after passing through the condenser.

of gaseous ammonia entering zero room.

n " " " 30 degree room.
" " " leaving 32 " "
" R n " zero room.
Water:

of inlet to condenser and jacket.
24.6

Temperature of outlet to condenser.

. " Rr " jacket.
Weight of jacket water.

. " condenser water.

Motor.
Volts, amperes and rev.per min.
R. P. M. of compressor.
A separate test was run on the motor to determire the horse power
input to the compressor for each observaticn of volts and amperes.
The following observations were taken on this test:

R. P. M. of motor.
Volts.
Amperes.

Net weight of brake arm.

Displacement 100% Vol. Eff.
6* x 6" Cyl. |
28.27 x 6- 170 cu. in. in one cylinder.
170 x2 = 340 cu. in. in two cylinders.
R. P. Me. = 108.3

040 x 102.3 = 20.1 cu. ft. Min. Displacement
1728

60.1 x 60 x 24 = 28950 cu. ft. in 24 hrea.
Amount of Ammonia Circulated.
Avg. temperature of gas entering compression = 40.6€ (;
Gauge Press ~ 9.1 = 23.8 =7185:
l# Ammonia at 40.69 F #& 33.84 55. = 13.3 cu. fte
According to tables of superheated ammonia in tables in Kent Pe. (1341)
(by interpolation)
 
B56

28950 cu. ft. = 2172 # Ammonia in 24 hr.
13.3 cu. ft Theoretical.

Refrigerating Eff. Theoretical.
Latent Heat of Ammonia 9.1 gace press = 561.6 87.
el7s = wt. of Ammonia circulated.
el7e x 561.6 © 1,235,000 B. T. U. in 34 hr.

Avg. Temp. entering expansicn valves. = 67.8 F
" " after complete expansion - 35.6
350m

508 (P—?770

Specific heat of Amc.conia gas

Wt x Sp heat x t e m change B.T.U.
el7e x .508 x 32.2 = 35500 B.T.U. Used in cooling the ammonia and

not available for refrigerating.

1,235,000 - 35560 = 1,200,500 B.T.U. Available.
Heat Required to Melt 1# Ite = 144 B.T.U.

1 Ton = 2000 x 144 = 288000 B.T.U.

1,300,000 + 388000 = 4.15

4.15 Theoretical Tonnage 100% Eff.

Using 75% Vol. eff.

Tonnage - 3.12 tons per 34 hr.

Work of Adiabatic Compression.
Pl = 23.8 abs.
Tl = 40.6" F
167.7 abs.

PE

T2 = 1249.4 F,

Temp. corresponding to Pl = - 10° F (Saturated)
— es
40.6 = (-10) = 50.60%. superheat at suction
Entropy at this point = 1.267164
Assuming adiabatic expansion and
Constant entropy change
From tables
Total heat at Pg To = 715.6 a7.
Total Heat at P1} T1 = 567.9
Diff = 147.7

2172# of Ammonia in 24 hrs.
e172 x 147.7 = 321000 B.T.O0. in 24 hrs.

Work of Compression (Assuming Adiabatic Change of State)

Cooling Water
Wt. of Water passed (Jacket) - 717#/hr.
Change of temp. in (Jacket) = (68.9 -61.5) = 7.4 7
717. x 7.4 = 5310 B.T.U. pet hr.

9310 x 24 = 128000 B.T.U. in 24 hr.

at.
1620

\\

Wt. of water/hr. passed (cond)
10.4 °F

Change of tem. = (71.9 - 61.5)
1620 x 10.4 = 16850 B.T.U./hr.
16850 x 24= 405000 aru/orr
405000 -$128000 = 533,000 B.T.U.
Absorbed by cooling water in 24 hr
Heat Balance.

(Heat of Refig) + (Heat 9€ comp) = B.T.U. Taken up by water

4- losses

266
 

a

eee

—
B76

Refig. Comp- Water Rad.
1335000 -- 321000 = 533000 -#1033000

EFFICIENCY (Wood P 323)
of Compressor - Energy obtai work
Energy Expended

EK -He H, ~ heat carried away

—— by condenser

Hy) - Hp

H = heat taken from ref. room
Eff = 1,200,000 = 4.74
863, 500

The reason for his eff being greater than unity is be=-

cause this is a heat engine reversed.

KoW. Hrae Per Ton Refig.
5644 K Wx 34 = 131 K. W. bre per day

131 <=438. kK... houss per ton ref.

Sele
28-6

 

 

Motor Ave. Read.
Load
uross Net Volts Amps R.P.M.
0 0 ell 4 793
B59 9.375 210 6.5 750
20 34.2375 206 15 730
75 69.375 203 22 709
90 74.375 200 29 701
100 84.375 199 28 695
110 94.375 198 31. 687
120 104.375 196 35 682
130 114.375 195 37 675
140 134.375 195 4C 663
Load Input Output
Gross H.P. K.We Eff __B.H.P, _
0 1.13 844 O% 0.%
SO 1.83 1.364 47%, ~86
50 4.14 3.090 74% 3.06
75 6.1 4.549 96.6 5.83
90 6.7 5.000 94.7 6.35
100 7247 5.579 95.5 7.15
110 8.23 6.149 96-6 7.9
130 9.18 6.850 94. 8.6
130 9.65 7.200 97.4 9.4
140 10.48 7.800 95.5 10

 

 
ts.

ay Cooling
water
Time. Temperature
C 4
@
a
eR» pp
+p +9 © ® Oo ®
@ @ CG od rt
rH - SP Oo»
# GS on co
Ht tH OO KO
$330 14. 18 16
9:00
9:30 16 20 20
10:00 17 ey 22
10:30 17 22 21
11:00 18.5 21 31
11:30 17 20 20
12:00 18 24 23.5
12330 17.5 25 23,
1:00 1g. 23.5 22
1:30 17 22.5 17
2:00 17 24 17
2:30 16.5 22.5 23.5
3:00 19 22.5 26
3:30. 17 el 17.5
1:30 15 19 1g0
2:00 15 22 19
2:30 16 23 20
3 :00 16 21 19
: 30 16 20 20.5
:00 17 ey 25
$ pws
Mean 15.8 21.5 20.25
f°: 60.4 70.6 68.4

Compressor
Temptiire Press
@o ©
Oo oO
s 8 § 3
pF So >, °%
© a Oo m
a a €& aA
0 Y 2
2 BR
S 53 150
65 30 CB ahs
rn re
63.5 55 7 145
63.5 53.5 8 155
2 56.5 2 157
2 54 10 #42157
2 1 & 152
0 9 S& 155
2 49 { _ 157
1 51 7.5 170
4 53 { 15e
16¢ 50° 67 130¢
14 51 6% 150
OF 53 15 155
6F 51 S&S 145
13 50 7 143
23 52 { 153
60 0 1 876
e 2P e
10 51.16 8.5 146
50 124

ty
Ne
Zero 32° “ wotor.
Room Room Q
ow
Temp. Temp. Temp,
@

° 42 4 oO
ra » © we ® m #4

° @ r- @ am | » @
* #8 8 2 8 3
fon H Oo oO > §
100 60 35 15 60 16 205 26
102 «20 2 2 54 16 205 2
105 12 45 5 51 17 205 2
102 2 49 5.5 50 19 200 ek
102 49 5 51 19 200 24.
104 10 4g 8 52 20 200 26
103 13 46 6 53 22 200 25
102 #12 4 10 53 ei 200 27
104 411i 2.5 pe 22 200 2g
103 16 13 #210 465 22 200 28
100 15 11 #10 44 22 125 23
102 615 «10 «#210 Wl 23 195 28
103 12 9 #10 42 = 22 200 28
102 13 & 9 47 22 198 29
102 12 #217 9 50 215 200 27
10 13.

; ; 45 45 50.2 64°F 200 26
103 14 29.5 4.5 51 64 F 200 2&
102 «614 120 120 40° 170CF 200 23
10 go ll 9 22eF 19C 200 2s
10 72 10 ? ene 19c = 200 26
103 70° 27 O 20c 200 28
618 64.5 134.0 42 6.2 110.4 164.
OpB Spee SPO tase Ales ss

103 10.75 22.3 6.8 39.3 a 200 23.3 7

R.P.u.

SII NININININIAIN
HORPKHRPRHHOO
UT! 19 0207 1 10 02 O

le

718

720
721

723
722

432

20.8

Friday
War. 3l.
19 4%

Thur.P..
Liar. 30tt
FARENHEIT,

Cooling Compressor. Zero. 329
Water, Room. Room, Motor.
Time. Temperature. Temp. , Press, Temperature Temp. Temperature.
H @ @®
@ a0 oO ° tH
a 42 S 4 cS 4 =] © a
Cc oO 2» Oo Oo o Sad ad > @ °
» oO 4+ © ® ort G ort Ss ° oe © 42 © ad m a =
o 3» “4 + oO » oO A, @ i o - @ rt 9) e
‘a 56 88 8 8 = o ; A 3 a 3 © o oF "
HH ©) ry O m A wu Q fom H oO Hi oO fan oad § fon
MET.
30 60.4 70.7 684 50 124 8.5 146 103 #2210.75 22.3 6.8 39.3 65.1 200 27.3 720
39 63.8 72 70.6 32 123 6.85 154.5 102.3 15.77 28.7 & 4 49.7 68.3 200 26.3 710
Acr.,

lst 60,2 07 «4
eS 0 °! 7 7126.3 12,08 158,46 101.5 V4.9 37-38 16.2 46,2 69 203 e7.f = 10

otal 124.4 215.7 206.6 121.9 373.3 27.4 459 306.8 41.4 88.4 31.4 125.2 203.4 603 81.3 214
Ave. 61.5 71.9 68.9 40.6 124.4 9,1 153 102.3 13.8 29.5 10.5 41.7 67.8 201 27.1 713..
— ri WVU TRU U4 — wr Te 4 rm WU a VU -

cO 14 14.5 14 © 7 1 13 100 3 7 3.5 2 18 205

30 14 23 18.5 10 5 WY 160 100 9 1 12, 2 16 202
OO 8614.5 23 21 12 5 1 165 100 =—si16 us 6 19 4200
302 15 22.5 21 12 57 1 165 100 17 ue 1 4$ 20 £198
,00 1 25 ay 12 59 16 79 100 19 51 21 47 21 200
*300—O1 23 20 -1i1 pie? 16 165 100 20 26 20 Hf29 22 200
rcO.)—/ «14519 15 -14 S.5 15 13) 100 19 20 20 9 21 205
30 14.5 23 1 -10 47, 13 160 101 17 23 21 50 21 203
co.)hOUl 22 620—Cl—si-17 51 11 139 103 1 31 22 50 21 203
130 026041 24.5 20,5 -12 54 12 163 103 1 7 16 50 = 21.5 205
.00 18 24.5 24 12 56 11 160 103 4.5 41 14.5 50 22 205
30 18 au 24 1} 5g 10 157 105 14 Wi 15 5030s 22.5 203
:00 17 24 22 1 58 11 157 105 14, 45 15 50 22 207
203.5 296.0 2560 7 6805 157 2065 1320 193,5 486 210 005 2690 2637 3
45 a
15.65 22.86 19. 44 8652.34 12,08 156.46 101.5 14.9 37.38 16.2 46.2 20.6 203 27
602 73 67. 37.9 126.3 69

Thursday P.M. 1916 March 30

1 WATER Time,

Temp. of Temp. of Room No. & No. 9

F F Temp ¢
Zero Room 329 Room

-y 23 19 1:30
-6 23 20 1 1 2:00
. 2 20 1 2:30
= 2 20 1 1 3:00
-4, 2 21 , 1 2:20
-6 2 21 (5/9) 1(1/8) : 00

 

 

 
Friday, March 31, 1916,

870° 77
Rocm Temp. Compressor Comp. « Condenser
Tanks,
Time O° Room 32° Room Ref. Room No. 8 No. 9
6:30 Plu, © F 2s F 64 F
9:00 - 20 F 29 #F 66 F 1
9:30 20 F 29 66 1
10:00 - 20 28 70 1
10:30 - 4° 28 72 1 1
11:60 - 4 28 75 1
11:30 -2 2s 76 1
12:00 Nocn - 3 e7 7&8 1
12:30 P.u. - 4 26 78 1
1:00 - 4 26 78 1
1 1
1:30 - 4 25 79 ,
2:00 - 4 oy. 79
1 1
2:30 -4 24 74 ,
3:00 - 4 ey 13
3:30 - 4 ey 76 735 760
Saturday, April lst, 1916,

Tanks
Compressor Condenser
Room Temperature - S70 * 377 *

Time O° Room 32° Room Comp. Room F. No. & No. 9
9:00 4 33 67

9:30 2 33 66 1
10:00 1 32 6g 1 1
10:30 0 30 66 1
11:00 1 30 66

11:30 2 29 66 1 1
12:60 1 eg 6%

12:30 1 2g 71 1
1:00 0 27.5 73. 1 1

1 :30 0 27 73 1
2:00 -1 25.5 74 1 1
2:30 1 26 74 420 1
3:00 -3 26 75 700

 

 
Wt. of brake arm
Cir. Brake Pulley
Dia. Motor "

Cir. Pulley on Comp.

Total
Load

25
50
75
90 _

100

110

120

Oo @ 3 OD NO ff A ND }

130

rar)
©

140

~
O

140
130
120
110
100
90
75
oO
25

Mo WD Ff OO oO NVQ Oo WO

Volts
e212 8 all
218 109
B08 204
204 300
201 198
200 197
200 196
196 194
195 194

195 192
195 196
196 197
196 197
198 198
199 199
BOL 2028
203 303
B06 206
210 1109
610 2132

15-5/8#
4t 3/8"
6-11/16"
12.86!

Amperes
4
6.5
14
20.5
24
27
29

32

33
39.5
40
37
35.5
32
28

22
17

6.5
4.5

May 2nd, 1916.

May 2nd, 1916.

R.P.M.

o 750

6.5 749
14 731
1 708
BO 795
27.5 692
30.5 687
38 686
3209 676
39.5 664
40 667
38 674
36 682
32 689
28 698
26 699
aS 710
17 730

? 753

4.5 757
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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References,
Refrigeration wemorandg - Levey
Ammonia Refrigeration, - Redwood
The Principal Professional Papers, - J.A,L,Wadell
Practical Cold Storage, - Cooper.
Thermodyamamics, Heat Wotors & Refrigeration Machines, - wood,

International Library of Technolosy, -
Technical Thermodynamics, - Zeuner.
York life. Bulletin No. 10, Liodern Refrigeration Machinery, - Lorenz,

Pope,Haven, Dean.

Elementary “echanical Refrigeration, - Mathews,
Commercial Engineering for Central Stations, - Williams & Tweedy,
Tezwzt of Engineering Thermodynamics, - Lucke Flathes.
Handbook, - Kent.
Heating and Ventilating, - Hoffman
Tnhermo-dynamics, - Goodenough.
Heat Engines, - Allen & Bursley.
Outlines cf Chemistry, - Louise Kallenber:;.

Ice and Refrigeration lUagazine, ¥ol. 49, No.1,
Heat Engineering, - Greene,

Thermodynamic. Prosrerties of Ammonia, - Keyes & Brownlee,