Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 0220622~ l997-05-28
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W096t17~14 PCT/EP95~04167
EvAPOFuhToR ~OR A COMPRF~R-~YPE c~PTr~T~Y C~Qr~T7~C UNIT
~he ~nvention relater to an e~aporator ~or a compressor-~ype
cooling unit comprisin~ at least two mQtal ~heets ~irmly jolned
~echanically to one another by welding or soldering, wherein
zones o~ the ~etal sheets are farmed into channels to c~a~e a
coolant channel of unifor~n or partially ~7aria~le cross-section
ex~ending in meander ~hape ~etween the mstal ~heets, the me~od
adopted to this end be~ng that a welding-impeding mater~al which
precisely i~age~ the subsequent course of the coo~ant channel is
applied to at least one of the ~e~al sheets on the ~id~ adjacent
the other metal sheet, wherea~er the two ~etal sheets ar~
~oined, ~ccompanied by the stretching of the substra~um and the
inclusion o~ thQ coolant inlet cross-section and the coolan~
outlet cross-section, internal p~essure then acting upon said
zon~s, and wherein th~ e~aporator is connected via a dr~er and~or
a conden~er to a compr~ssor and has a capillary line, discharging
into an enlarqinq channel cross-sec~ion cons~ructed a~ an
injector, for the introduction o~ khe coolant in the liquid
pha~e, an~ a line ha~lnq a substantially large~ cro~-section
than the inlet line for the diccharge o~ the coolant in the
vapour phase.
~s ~or a caoling chamber, as a rule evaporators o~ thY kind
specified are ~rmed f~om suitably ~lat evaporator pla~es, whi~h
a~ter shaping and in the incorpora~ed state each bound o~ one
_
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side or enclosed on se~eral ~ides one or more cooling chambers o~
a cooling unit and fregu~ncy also ~or~ the rear wall of such a
cooling cha~ber.
Evapora~or plates o~ the kind speci~ied and their production by
the roll ~ond process are disclosed, ~or example, in DE-PS 15 52
044.
In the roll bond process, in which the two layers o~ the plate
are connected to one another ~y a sealed assembl~ rolling
proces~, accompan~ by the stretch~ns of the subs~atum,
~eparating layers o~ welding-impeding material ensure pre~isely
bounded a~eas forming the su~sequent cour~e of ~he coolant
channel. This 6tep i~ disclosed, ~or example, in DE-PS 19 20
4Z4.
As a rule, shaping is per~ormed by the use o~ comp~essed air,
which is introduced between the unwelded zones of the channel and
~y means of the internal pressure generated at that place deforms
one or both of the plates welded togeth~r, to form channel cxoss-
sections.
In the pas~ the coolant used was solely h~drocarbon (~C
h~drocarbons), while no~aday~ more ~,odern cooling ~y~tems as a
rule use materials ~ree from FC hydrocarbons such a~, ~or
example, butane.
In parallel with the use of new co~lants, nowadays other
constructional safety regulations must be observed whose main
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aim is in the future to pre~ent the cooling chamber from
containing critical place~ in thz e~aporator zone - i.e.,
essentially connecting places between identical or different
materials, pressing plac~s, joining places or Zones which are
heavily ~ent and there~ore ma~ be heavily p~ede~ormed and hav~ a
red~ced cro5s-~ec~ion.
In future cooling units, therefore, such critical zones must be
disposed outside the cooltng ~h~hPr and outside the insulation
enclosing the cooling c~ber.
This comes up again~t difficulties, more particularly ~here the
arrangement o~ such cri~ical zones outside the cooling cha~ber
leads to cooling losses or energy losses.
This is the case, ~or exa~ple, i~ the connec~ing place b~ween
the capillary sup~ly line to the inlet of the coolan~ in the
liquid phase and th~ evapo~at~r is placed in the zone outside the
coolin~ chamber~
Conven~ionally said connecting place i8 SO p~oduced by presslng
~hat the capillary lin~ is ~ntro~uced lnto an already widened
portion of ~he channel extending ~eander shape and has
adhesive~connecting a~ent on i~ outer ~eriphe~y, whereafter the
portion of the evapora~or channel now enclosing ~he capillary
line is presred to the capillary line in a pr~6ing apparatus.
Since during ~he pressing operation the capillary tube may easily
become da~a~ed or e~en shorn ~f~, or at least zones o~ the
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chann~1 cross-section may ~e overexpanded in the evaporator, this
is one of those critical place~ which must necessaxil~ Pe
transferrPd $rom the inner cooling chamber zone to the outsid~
zone.
HoweYer, in ~hat conventional manu~act~ing process the capillary
tube still extends do~nstream o~ the pres~d zone into the
portion of the coolant channel which ~as originally pr~sent or
even was deliberately widened ~o act as an injecto~, so that the
sudden and very considerable expansian of th~ coolant intro~ced
whirh at this place res~l~s in ~n e~tre~ely heavy cooling of the
surroundings.
If therefore the connecting place or the portion of the
evaporator im~edia~ely ~ollowing that place and si~uated in the
zone of heavy cooling i5 placed outside ~he cooling chamber for
sa~ety reasons, at that place consldera~le e~ergy losses occur
due to cooling outside tn~ coolin~ cha~be~.
To avoid these losses, attempts h~ve alread~ ~een made to base
the connecting place between the c~pillary tu~e and the
evaporator again closer to the internal space or therein, givin~
s~id place protection separately by plastics envelopes or safety
space~ Howe~er, ~or reasons o~ sa~ety techni~ues these attempt~
are suita~le only to a certain degree for the p~rpose o~ ~inding
a solut~on or correlating the 6a~ety aspects wl~h id~as
concerning low energy coolinq sys~ems.
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~t was therefore an object o~ the invention so to construct more
particularly the critical zones in the connection of the
capillary line to the evaporator that on the one hand the safety
techni~ue aspects would be completely achievable and the
connecting places could be constructed outside the cooling
cham~er, other objec~i~es being to keep enerqy losses as low as
po~sible, to simplify prod~ctlon an~ to avoid i~ponderable
aspects in a press~ng and~or sold~ring connection between a
capillary channel and a coolant channel. These pro~le~s are
solYed by the features o~ claim 1.
Further advantageous ~ea~ures o~ the invention are se~ ~orth in
~he subclaims.
Accor~ing to the invention, ~here~ors, the capillary line ~or the
introduction of the coolant in ~he liouid phase is construc~ed as
part of the evaporator in the ~orm of a capillary channel which
extends between the metal sheets and is constructed and shaped ~s
the ini~ial portion o~ the coolant channel extending in meander
shape and ~ag any cross-5ection hydraulically equival~nt to t~e
round cross-section o~ a capillary line.
SuCh a construction of ~he inlet side coolant channel in the ~o~m
o~ a capillary channel ~a~in~ a cr~ss-section hydraulically
~guivalent to the round cros~-~ectlon of a capillary line enable~
the change in cross-section in tha coolant channel and the
injector zone to be transferred to any reguired place in the
evaporator plate and there~ore to a zone inside the cooling
cham~er which is non-critical as regards energy losses.
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A~ the sam~ ti~e, the connection of a capill~ry tube leading on,
~r example, to the dryer or the conqenser is simpllfied by the
fact that due to ~he ~ubstan~ially identical cross-section~ o~
the capillary channel and capillary ~ube, saldering can be
per~ormed, and the pressing and squashing o~ the ~wo lin~
elements conventionally used in the prior art can be completely
eliminated~
The soldering o~ such substantially identical cross-sections al50
prevents accidental widening o~ the capillary llne and there~o~
the expansion of the cooling ~luid in zones out5ide the cooling
chamber an~ there~ore advanced injector function.
~uch a con~truction there~ore takes enhanced consideration of
sa~Qt~ into account, while a~ the 6ame time minlmi2ing energy
losses.
In a more particularly advantageous embodiment a line ~o~ the
di~charge o~ the coolant in ~he vapour phase takes th~ ~orm of
the end portion of the coolant channel extending in ~eander shape
between the ~etal sheets and extends on the inlet side a~ove the
injecto~ parallel wit~ a~d ~mmediately adiacent to the capillary
channel .
As a result, in the very simplest manner a heat tranefer is
achieved ~rom tlle coolant in vap~ur phase ( "hot ~as" ) ad jacent
the outl~t from thc e~aporator to the coclant in the capillary
channel J which is still in the liquid phase and at high pressure.
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In this case heat transfer is per~ormed ~n a particularly
advantageous manner to a su~stantial or~er o~ ~agnitude by the
thermal conduction o the ~etal of the coolant channel and lock,
as for exa~ple in th~ prior ~t, essentially by heat transfer
~etwe~n boundary layers of secon~ lines interwo~en with one
another.
This heat transf6r further increases the pressur2 in ~he coolant
supply line, the result ~eing a further enhanced cooling
per~ormance during expansion in ths injector.
Accord~ng to another ad~antageous ~eature of the invention ~he
outlet of the coolant in the vapour phas~, takin~ the ~or~ of t~e
end portion o~ ths coolant channel extending in ~eander shape and
the capillary ~hAnneJ ar~ a~ 18ast part~ally disposed on a shee~
van~ forming part o~ th~ m4tal sheets only joined mechanically to
one ano~her by welding or solde~ing.
After the production o~ the evaporato~, such a sheet vane can
readily ~e bent and taken into any desired zone fo the c~oling
~nit, the result being ~xtremely si~ple adapta~ion to th~
par~icular shape o~ ~oolin~ ch~mh~r ev~n during manufac~ure.
A ~urther advantageou~ ~eature o~ the i~vention i8 that the shee~
vane is connected ~ia individual short, thin webs to thc rest of
the e~aporator, ~r that fir-~t the evaporator plate must ~e
produced which can ~e transported in a simple wnd satis~actory
manner w~ile its production, adapted to the particular cooling
unit, and pro~lem-f~ee incorporation are ensured by merely
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tearing or bending o~f the.shee~ m~tal rod~ and bending the sheet
vane as reguired b~ the geometry of ~he cooling cha~ber.
Othe~ advantages deriving from the simplif~cation of the soldered
connection are ob~ne~ i~ the evaporator connecting lines
extending to th2 compressor and/or the dry~r or the condenser
take the ~rm o~ tubing made ~rom a ~aterial co~responding to the
~aterial of the evaporator~
As a result, no intermediate shells or supporting xings are
required during soldering, so that a simple standard soldering
per~ormance must be per~orm~d. It is advantageou~ and ~akes
sen~e as regard~ ~urther and enhanced heat exchange ~e~ween the
inlet line and the cutlet line t~ have a construction wher~in the
connecting lines extend~ng ~o the compressor andfor to ~he dryer
or condenser are in material contact with one another or are
interwoven with one Pnother.
In add~t~cn to ~he ~urther enhanced heat transfer, in thls case
the relatively sensit~ve capillary llne is supported ~y the
thicker and larger hot gas line between the evaporator and the
cQmpressor.
In the already-described slmple solderin~ of ~wo tu~es o~
substantially id~ntical c~oss-section, advantageou~ly the
connect~na l~nes extending to the compre6s~r and/or the dryer or
condenser have a short-thick welded and/or expanded end.
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The result is a supporting func~ion of the soldering place,
although the widening or the upset end of the particular line
does not act as a widening in the sense of an in~ector. This is
substantially ~oosted by the construction o~ the cap~llar~
channel which is pr~sent on th~ sheet vane and which, due to ~he
construction of a cross-section hydrauli~ally eaui~alent to the
round cross-section of a capillary li~e, opposes to the in~lowing
coola~t in the liquid phase a ~low resistance SUCh that there ls
no risk of any expansion in~ide the soldered connection place~,
which takes place in a controlled manner only at the ln~ector
con~tr~cted inside the evaporator plat~.
The invention will now be explained in greater detail with
re~er~nce to an embodiment thereof. The drawin~ show:
Fig. 1 an evaporator accord~ng to the invention, having an inlet
side capillar~ channel ~xtending parallel with the hot
gas channel,
Fi~. 2 a ~ew and an eleva~ion o~ an evaporator according to th~
invention havin~ a sheet vane bent ove~ a la~ge area.
Fig. 3 an evaporator as shown in Fig. 2, ~t having a ~erely
shortly bent ~heet ~ane J and
Fig. 4 a cooling sy~tem having an evaporator accordin~ to the
inY~ntion,
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Fig. 1 shows an evapo~ator 1 according to the invention i~ which
a dischar~e side hot gas channel 3 extends parallel w~th a
moulqed capillary channel 2. The two chann~ls form parts o~ a
coolant channel 4 in meander shape producsd by the roll bond
prooess.
In ~he zone wh~re the hot gas ch~nnel and the capillary channel
extend in parallel, an intensi~e heat exchange ta}ces place
between the discharged coolant in the vapour pha~e and the
coolant s~pplied in the li~uid phase.
The channels extending parallel as ~ar as shortly upstream of an
in~ecto~ 5 taking ~he ~orm of an enlarged cool~ng channel in
which the li~uid coolant is expanded and in which the heavy
cooling effect starts.
~hese t~o parallel hot gas and capillary channels ex~end
partially over a zone o~ ~he evaporator 1 taking the fo~m o~ a
sheet vane 6 which is connec~ed via a W2~ 7 to the evaporator.
The web can be ~roken o~ bent o~ as required and in ~ccordance
with ths tnc~rporated position o~ the e~aporator in th~ caolin~
unit, wherezf~er the sheet vane 6 can be bent into any requl~ed
position and directio~. Tubes 8 and 9 made fro~ substantially
the 6ame material as ~hs evaporator and carrying the ho~ gas an~
coolant suppl~ re~pectively are connected to the end o~ the s~ee~
vane 6. The connections of sub~tan~ially identical size between
~he lines and the evaporator channels are c~nnected via weldin~
places 10 and 11. SuDh an arra~gement o~ the iniector and
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connections of identical c~oss-section prevents inter alia the
noise often criticized which ta~es place during inflow through
~he inlet tu~e pressed into a coolant channel in ~h~ prlor ~r~.
That noise iB caused ~y uncontrolled flow on the walls, rebound
ef~ects and the exci~e~ent o~ oscilla~ion of ~he often free
capillary tube end.
Fig. 2 shows the etJaporator according to th~ invention to an
enlarg~d scale in the for~ of a view and an elevation, the sheet
vane 6 present in this place can ~e bent over a relatively larg~
a~ea. ~his results fro~ the double ~olding o~ the sheet vane,
shown in the left-hand part o~ the drawing, and th~ sheet we~s
present at the place~ 1~ and 13, ~hich can be bent as required.
In thi~ case the injector i~ situated substantial~ at place 14
and there~ore inside the cooling chamber, while the sheet vane 6
~ent for incorporation exten~s far out of the cooling ch~mher
insula~ed, ~or example, with a foamed material 15 and can be
connected t~ the assacia~ed elements in anY re~uired manner.
Fig. 3 shows the evaporato~ as illustrated in Fig. z, b~t slmply
with a bent web 1~ and the resulting consiflera~ly reduced bendin~
o~ the she~t vane 6.
Thie ~akes the varie~y cf possi~l~ applications particularly
clear, since the selecta~ility of the bending angle ~llow~
adap~atio~ to the places o~ incoxporation of the other components
of cooling units as required.
::
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~ig. 4 shcws agai~ an overall view o~ the complete arrangement of
a cooling unit havin~ an e~aporator according to ~he invention.
~he drawing shows clearly ~he sheet van~ 6 adjoining the
evaporator 1, and also the injec~or 5, ~hich is disposed in the
evapora~or plate~ Connec~ed to the evaporator via the soldering
place~ lO, 11 are the lines for ~he hot gas and the liquid
coolant 8 and 9, which are in~erwoven with one another or wound
round one another in the zane 16, tc achie~e a ~u~ther enhanced
heat exchange.
The dryer 21, the conden6er 22 and also th~ conne~tions o~ the
compre~60r lB extend outwards via ~he soldering place~ 17, 19,
20, the result being a ~l~sed system which trans~exs all the
connecting places outside the cooling cham~er and reduces energ~
losses t~ a minimum.
