Патент USA US2139297

‘ Dec. 6, 1938.
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J. G. BERGDOLL
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2,139,297
REFRIGERATION
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Filed March 6, 1937
DIRECTION OF
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attorneys
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Dec; 6, 1938.
2,139,297
J. G. BERGDOLL
REFRIGERATION ‘
Filed March 6, 1957
‘ 2 Sheets-Sheet 2
DIRECTION OF AIR. FLOW
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FROM DISTRIBUTOR,‘
DIRECTION OF‘AIK'FLOW
3nnentor
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Patented
2,139,297
6, 1938
Q" UNITED STATES . PATENT ‘ OFFICE
REFRIGERATION
‘ ‘ John G. Bergdoll, York, Pa., assignor to York Ice
Machinery Corporation, York, Pa., a corpora
tion of Delaware
' Application March 6, 1937, ‘Serial No. 129,475 I‘
13 Claims.
This invention relates to refrigeration andpar
cold end of the coil at a point where the air is ,
also cool and can supply little heat to establish
the superheat demanded by the thermostatic ex
pansion valve. Hence an abnormally large por
ticularly to the cooling of a ?owing stream of
?uid by a refrigerative evaporator fed by a ther
mally controlled expansion valve. The invention
5 will be described as applied to the cooling of a
stream of air, without however implying'the ex
clusion of other gases or even liquids.
tion of the evaporator is used to supply superheat
and is, in consequence, relatively ine?ective to
refrigerate. If a.» more effective superheater can
be arranged the coil can be more nearly ?ooded
The fact that an evaporator converts the sensi- '
'ble heat abstracted from the air into latent heat,
10 leads to special e?ects which must be appreciated
if the invention is to be understood.
Consider two streams of liquid, one hot the
other cold, exchanging sensible heat through a
surface exchanger. ,As is well known, concurrent
vl5 flow permits both liquids to approach a mean
. rator into two sections, a small superheater sec
tion with which the air ?rst exchanges heat and
by which the air is somewhat cooled, and a larger
main refrigerating section with which the air .
the other. Obviously counterflow gives a more
nearly uniform temperature difference and conse
Refrigerant from the expansion valve enters
the main refrigerative section and ?ows there
through in concurrent ?ow relation with the air.
Refrigerant discharging from the main section is
then passed through the superheater section,
preferably, but not necessarily in counterflow re
lation to the air. Since the superheater section
receives heat from the warmest (entering) air,
signed evaporator of the ?nned tube type causes
' a pressure drop varying from 2 to 6 lbs. per square
inch from inlet to outlet, depending on operating
30 conditions. The temperature of successive points
in the evaporator must fall correspondingly. Ac
cessions of heat evaporate liquid, but so long as
liquid is present do not increase temperature.
The pressure alone controls evaporator tempera
ture.
,
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perature reduction is eilected.
.
it is highly effective and need form only a small
fraction of the entire evaporator.
_
Such an arrangement gives more steady opera
tion, better thermal control, and larger cooling
capacity than can be had by- either concurrent 30
?ow alone or counter flow alone.
The main sec
tion can be operated nearly ?ooded, the refrig
erant flow is rapid and in consequence the total
evaporator surface may _be made ‘smaller in com
parison with similar evaporators heretofore re 35
Because evaporator temperature Jfalls in the
direction of refrigerant flow, concurrent how
fected in space and cost of apparatus are sub
(with respect to the air stream) gives results in
stantial.
an evaporator somewhat analogous to those se
cured by counter?ow inv the case of simple ex
quired for comparable loads. The economics ef
.
In modern'comfort coolers using refrigerants
such as F12 or Freon (trade names) it has been
change of sensible heat. Since liquid refrigerant
found desirable to use a plurality of evaporator ‘
enters the warmer end of the evaporator, evapo
ration and ?ash generation of gas are intense.
units connected in parallel and fed by a single
thermal expansion valve through a turbulent
mixer or distributer head which’ serves to deliver
uniform mixtures of liquid and vapor to the
Consequently rapid ?ow of\ refrigerant through
“ the evaporator is secured and greatly intensi?es
“
10
According to the invention I divide the evapo
next exchanges heat and by which the major tem
- erant in the evaporator is a function of the pres
25 sure; In an evaporator the pressure is never
uniform, for ?ow resistance in even a well de
'
approached.
temperature, whereas counter?ow permits each
liquid to approach the entrance temperature of
20 quently the most effective interchange where only
sensible heat is exchanged.
Now consider an-‘evaporator cooler cooling a
stream of air. The temperature ,of the refrig
35
and theoretical performance-can be more nearly
'
heat transfer.
The above considerations imply that 'an evapo
' rator fed .by a thermally controlled expansion
valve and cooling‘ a stream of air should be ar
50 ranged for concurrent flow and so arranged would
' carry a. refrigerative' load ‘near the theoretical
limit of the coil. Suchresults have not been at
tained in practice and the discovery of the reaso
is the basis of the present invention.
‘1; With concurrent ?ow, refrigerant leaves the
various units. The‘ invention will be described as r
so embodied, without implying the necessary use
of multiple units.
In the drawings:
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Fig. 1 is a diagram, partly, in elevation and
partly in section?showing a typical refrigerating
circuit. The direction of air flow is indicated by
an arrow and related legend. The duct is broken
away to show the evaporator structure.
. Fig. 2 is a perspective view of thetube forming
a
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2,189,297
the two sections of one unit of the evaporator in
Fig. 1. The ?ns are omitted so that the path of
refrigerant can be traced.
Fig. 3 is a plan view of the distributer head.
Fig. 4 is an axial section therethrough.
Fig. '5 illustrates a modi?cation in which the
?ns on the main and superheater sections are
distinct to minimize heat transfer between the
two sections.
Fig. 6 illustrates a further modi?cation.
10
Referring to Fig. 1, the suction line is indi
cated at 6_ and leads to the compressor 1. The
compressor is driven by motor 8 through a belt 9
and discharges through high pressure line I I into
15 a combined condenser and receiver 12. The con
denser chosen for illustration is water cooled
but this is immaterial. From receiver 12 liquid
line I3 leads to the expansionvalve, whose body
appears at i4.
The valve proper I5 is loaded in a closing di
20
rection by spring l6 whose stress is adjustable by
turning screw II. The valve is shifted to regu
late superheat in the suction line by diaphragm
l8 subject to the opposing effects of suction tem
25 perature and suction pressure.
The motor dia
phragm I8 is urged in a valve opening direction
by vapor pressure developed in thermostatic bulb
l9 by rising temperature and communicated to
the space above the diaphragm by. pipe 2|. The
30 lower face of the diaphragm is subject to suction
pressure communicated by pipe 22. Bulb I9 is on
the suction line and pipe 22 is connected adja
cent the bulb, so that diaphragm i8 responds to
the pressure-temperature relation at substan
35 tially a single point. A packing gland 23 pro
tects the lower face of the diaphragm from the
pressure on the discharge side of valve l5. Ad
justment of spring l6 determines the degree of
superheat maintained, conveniently l0° F. Other
conventional expansion valves with superheat
control or giving approximate superheat control
may be substituted.
For example, where a constant speed com
pressor is used, so that the pressure drop from
the expansion valve to the suction line is con
The units extend horizontally one above the
other. Each tube 28 connects at 29 with the
evaporator tube 3|. This zig-zags upward in a
vertical plane for three passes, offsets to the
right, then zig-zags downward for three passes, CR
again offsets to the right and so on through six
tiers of passes to 32. Stated directions refer to
Figs. 1 and 2 and the number of passes is subject
to variation. The tube 3| from 29 to 32 forms
the main evaporator.
From 32 the refrigerant 10
is led back to 33 which is the entrance to the
superheating unit. This is formed as a continu
ationv of tube 3|, and zig-zags upward three
passes, offsets to the left, zig-zags downward
three passes and enters suction manifold 35 at 34. 15
Suction line 6 leads from manifold 35 at about
mid-height and the ?ller piece 36 is placed in
the lower half of the manifold to accelerate flow
there and inhibit the accumulation of liquid.
Such accumulation, if permitted to occur would 20
retard flow through the lower units, and would
produce a false temperature condition at the
thermal bulb as compared with the actual gas
temperature leaving the coil circuits
In Fig. 1 all four units including both sections
of each unit are provided with a series of parallel
plate ?ns, the ?rst one of which appears at 31.
These may be of any known type and either ?at
or corrugated. The entering air may be fresh
air, recirculated air or a mixture of the two. 30
The air ?ow is directed in contact with the
evaporator by a duct 38 and is induced by a fan
39 or other suitable means.
In Fig. 5, which shows a modi?cation, two dis
tinct sets of ?ns are used 318 on the superh'eater 35
section and 31m on the main evaporator section.
This thermal segregation of the sections some
what improves performance, but the improve
ment is not great enough to justify the extra cost
in‘ all cases.
40
In Fig. 5, as in Fig. 1, there is a distinct super
heater section for each main section, but this
need not be so, for all the main sections may de
liver to a single superheater. Fig. 6 shows this
arrangement as well as other optional features.
In Fig. 6 distributer head 25a is fed by an ex
stant, connection 22 and packing 23 can be omit
ted. The expansion valve then responds to out
pansion valve (not shown) identical with the ex
pansion valve 14 of Fig. 1. Thermal bulb Na and
let pressure corrected for a constant drop
through» the evaporator by appropriate adjust- _ pressure connection 22a control this valve exactly
ment of spring l6.
as the similarly numbered parts in Fig. 1 control 50
From body 14 expansion line 24 leads to the
expansion valve I4. Branches 28a lead from
distributer head whose body is indicated at 25. head 25a‘to four main units the entrance connec
Pipe 24 leads to nozzle 26 (see Figs. 3 and 4)
tion being at 29a and the exit connection at 32a
which discharges in the center of toric turbu
which leads to manifold 30. Manifold 30 is con
lence chamber 21, producing therein violent ro
nected by pipe 33a to a single ?nned superheater
55 tary turbulence. Four symmetrically arranged
coil 34a from which the suction line So. leads.
tubular branches 28 lead uniform mixtures of
liquid and vapor from chamber 21 to four evap
orator units.
60
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The major pressure reduction occurs at valve
[5 but the tubes 28 or their entrance ori?ces or
louvers 4] alone contacts superheater coil 34a.
This is the warmest air available. After warm
both may be arranged to provide such throttling
ing coil 34a, this air and recirculated air fed back
from the conditioned space through return air
duct 42 and adjustable louvers 43, ?ow together
as may be advisable to balance the delivery to
the four evaporator units. There is also some
65
Fins 31a, duct 38a and fan 39a correspond to
parts 31, 38 and 39 of Fig. 1.
In Fig. 6 fresh air entering through adjustable
pressure drop through the evaporator.
While I show four units any suitable number
may be used. The circuit so far described is
largely conventional and no novelty is here
claimed for it. Equivalents may be substituted.
The invention here claimed resides in the
70 evaporator, particularly the connections of and
flow path through each unit with reference to
the path of air in contact with the unit. The
units are essentially identical and a description
75 of one will su?ice.
over the main coils in concurrent ?ow relation
with the refrigerant.
In any case illustrated the air flow is such that
the air ?rst passes in heat exchanging relation
with the superheater section (or sections) and
then in heat exchanging relation with the main
evaporator section (or sections) this last in con
current flow relation with the refrigerant. Such
direction as to Figs. 1, 5 and 6 is from left to right
as indicated by the arrows and legends on these
?gures;
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Some’ idea of the advantage of vthe described how in ‘heat eirchi it it ‘I v‘relation with an evapo
arrangement can be had by considering a typical‘ irator which comprises passing the fluid in heat
case.
Entering air at ‘80°, F‘. cooled-to 6%" h“. at
exchanging relation with a refrigerant super-.
heating section and then in heat exchanging re
lation with a main refrigerant evaporating sec
tion of an evaporator while supplying volatile lio
uid refrigerant under pressure to the said main
discharge with a suction pressure of 3d lbsQ cor
responding to 40° F., can ‘be assumed as typical.
With simple‘ concurrent ?ow, there would ‘be a
temperature di?‘erence of only 20° to impart a
10° superheat. By the present arrangement
there is a 40° temperature difference to impart
section, directing the refrigerant’ therethrough in
‘concurrent ?ow relation relatively to the ?uid
lll the superheat, yet substantially the entire ad
stream and thence directing it through said super- ,
vantage of concurrent ?ow is retained. its a - heating section in counter-?ow relation relatively
consequence the evaporator may be more heavily ‘to said ?uid vstream; withdrawing ‘superheated
" loaded and operates more steadily and ei?ciently. refrigerant vapor from said super-heating section
What is claimed is,—_- ~
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-' at a pressure lower than the pressure at'which
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l. The method of cooling a stream of ?uid hy said liquid refrigerant is supplied; and varying
?ow in heat exchanging relation with‘an evap
the rate of supply of liquid refrigerant in rela
orator which comprises passing the ?uid in heat. tion to thedegree of superheat of the withdrawn
exchanging relation with. a refrigerant super
refrigerant, to maintain said superheat substan
heating section and then in heat exchanging re
tially constant.
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lation with 'a main refrigerant evaporating. sec = ‘ d. The method of cooling a ?luid by evaporation
tion of an evaporator. while supplying volatile of a volatile refrigerant in an evaporative surface 27o
liquid refrigerant) under pressure to the said main cooler, which comprises circulating the ?uid in section, directing the refrigerant therethrough'in heat
exchanging contact with such cooler, per
concurrent ?ow relation relatively to the ?uid _ forming
the major portion of the cooling of the
25 stream and thence directing it through said fluid hy evaporation of liquid refrigerant to a suit
superheating section‘; withdrawing superheated stantiaily saturated vapor condition in» a major
refrigerant vapor-‘from said superheating section I portion of said’ cooler with respect to which por
' at a pressure lower than the (pressure at which
tion the how of ?uid and refrigerant are con‘»
said liquid r refrigerant is supplied; and varying
the rate of such supply of liquid refrigerant in
current, imparting superheat to the saturated
vapor so produced in a minor portion of said cool 3%
or with which ?uid substantially unauected by
exchange of heat with said major portion err»
relation to the ‘differential between a force pro»
portional to evaporator pressure and a force pro
portional to the temperature of said withdrawn
changes heat, and varying the rate of supply of "
0 refrigerant.
35
2. The method-of cooling a ‘stream of ?uid by
liquid refrigerant to said evaporator surface cool»
tion of an evaporator while supplying volatile
liquid refrigerant under pressure to the said main
surface cooler, which comprises circulating the
fluid in heat exchanging contact with such cooler,
or in‘ relation to the diderential between a force
flow in heat exchanging relation with an evap
proportional to evaporator pressure and a force ‘
orator which comprises passing the ?uid in heat a proportional to‘ the temperature of said with
" exchanging relation with a refrigerant super
drawn refrigerant,
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heating section and then in heat exchanging re~ ~
6.
The
method
of’
cooling
a
?uid
icy
evapora~
lation with a main refrigerant evaporating sec
tion of a volatile refrigerant in an evaporative
section, directing the refrigerant therethrough in »
concurrent ?ow relation relatively ‘to the ?uid
stream and thence directing it through said
superheating section in ‘counter?ow relation rel
atively to said ?uid stream; withdrawing super
heated refrigerant vapor from said superheating
section at'a pressure lower than the pressure at
‘which said liquid refrigerant is supplied; and
‘varying the rate of such supply of liquid refrlg
erant in relation to the di?erential between a
‘ force proportional to evaporatorpressiu'e and a
force proportional to the temperature of ‘said
withdrawn refrigerant.
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performing the major portion of the cooling of V
the ?uid by evaporation of liquid refrigerant to a
substantially saturated vapor condition in a major
portion of said cooler with respect to which por»
tion the ?ow of ?uid and refrigerant are con»
current, imparting superheat to the saturated va- .
por so‘produced in a minor portion'of said cooler
with which ?uid suhstantially unadected hy eu dd
change of heat with said major portion exchanges
heat, and varying the supply of volatile refrlger»
ant to said surface cooler in relation to the degree
of superheat of refrigerant leaving said minor Y
to maintain said superheat substantially
, d. The‘ method of cooling a stream of ?uidityv portion
constant“
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?ow in‘ heat exchanging relation with an evap
orator which comprlsespassing the ?uid in heat
"exchanging relation with a refrigerant super
“i. r'li’he method of cooling a ?uid hy evaporation
of a volatile refrigerant in an evaporative surface
heating section and then in heat exchanging re- - ‘cooler, which comprises circulating the ?uid in
latlon with a main refrigerant evaporating sec-'
tion of an ‘evaporator while supplying volatile
' liquid refrigerant under pressure to the said main
heat exchanging contact with such cooler, per
forming the major portionof the cooling of the '
?uid icy evaporation of volatile refrigerant to a
saturated vapor condition, in a plu
' section, directing the refrigerant therethrough-ln , suhstantialiy
rality vof parallel-flow streams in a major portion
65 concurrent ?ow relation relatively to the ?uid of said cooler with respect, to which portion the
steam and thence directing it through said super . ?ow‘ of ?uidand of the parallel-?ow refrigerant
heatlng section; withdrawing superheated refrig
erant vapor from‘ said superheatlng section at av
pressure lower than the pressure at whichsald
liquid refrigerant is supplied;- and varying the
rate of. supply of liquid refrigerant in relation to
the degree of superheat of the withdrawn refrig
erant, to maintain said .superheat substantially
constant.
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streams are concurrent, imparting superheat to
the saturated vapor so produced in a minor pon
‘ tion of said cooler‘ with whlch ?uid substantially ’
una?ected by the major portion of said cooler ex» 70
changes heat, and varying the supply of- volatile
refrigerant'to said surface cooler in‘ relation to .
the degree of superheat of refrigerant leaving said
i
minor
75
d. The method of cooling a stream of ?uid by
portion.
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8. The method of cooling a ?uid by evapora
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v2,139,297’
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tion of a volatile’ refrigerant in an evaporative
said ?uid; and a thermostatic expansion valve
surface cooler, which comprises circulating the‘ controlling said supply of refrigerant, said ther
?uid in heat exchanging contact'with such cooler, . _ mostatic valve being arranged to be controlled at
performing the major portion of the cooling of the‘ least in part by the temperature of refrigerant
?uid by evaporation of volatile refrigerant to a leaving said superheating portion.
substantially saturated vapor condition in a plu
‘ 11. The combinationfde?ned in claim 9, in
rality of parallel-?ow streams in a major portion ,which the main section comprises a plurality of
of said cooler with respect to which portion the units through which the refrigerant flows in par
?ow of ?uid and of the parallel-?ow refrigerant allel'and the superheater section‘ comprises a cor
10 streams are concurrent, imparting superheat to
the saturated vapor so produced by heat’ exchange
responding plurality of unitsthrough which re 10
frigerant evaporated in the main unit ?ows in
with‘- the warmest available ?uid approaching said
parallel.
‘surface cooler, and varying the supply of volatile
refrigerant to said surface cooler in relation to
15 the degree of superheat of refrigerant leaving
said minor portion.”
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9. The combination of ‘an evaporator compris
ing a minor superheating portion and a major
cooling portion; means for circulating a ?uid ?rst
20 over said superheating portion and then over said
‘main cooling portion; means’forgsupplying vola-‘
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12. The combination defined in claim 9, in
which the main evaporator comprises a plurality
of units through which the refrigerant ?ows in' 15
parallel and the superheater is'a single unit to
which all the units of the main section deliver
‘ refrigerant.
13. The combination of an evaporator compris
ing a- minor superh‘eating portion and a major 20
cooling portion; means for circulating a ?uid to
be cooled in heat exchanging relation with said
tile refrigerant to‘ said main cooling portion and
causing it to ?ow therethroughiin concurrent ?ow 7' evaporator; means for supplying volatile refrig
relation with said ?uid, then to ?ow through said exam; to said main cooling portion and causing it
superheating portion; and a thermostatic expan
to ?ow therethrough‘ and then through said su 25
sion valve controlling said supply of refrigerant,
said thermostatic valve being'arranged to be con
trolled at least in‘part by the temperature of re
frigerant leaving said superheating portion.
80
10.‘ [The combination of an evaporator compris
ing a minor superheating portion and a major
cooling Portion; means for circulating a ?uid ?rst
over said super-heating portion and then‘ over said '
main cooling portion; means for supplying vola
tile refrigerant to said main cooling portion and
causing it to ?ow therethrough in concurrent’?ow
relation with said ?uid, then to ?ow throughsaid
superheating portionin counter?ow relation with
perheating portion; means controlling the sup
ply of refrigerant to said evaporator; means re
sponsive~to the condition of refrigerant leaving
said superheatingvportion and serving to control
said supply controlling means; and means con
trolling the ?ow of ?uid to be cooled and serving
to direct the warmest available ?uid into heatex
changing relation with.said superheating por
tion and to cause the ?Juid to ?owin concurrent '
?ow relation with the volatile refrigerant in said
main cooling portion.
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JOHN G. BERGDOLL.
30