 opposite side, and moves along the bottom surface of the ceiling and the surface of the freezing chamber defining wall behind the freezer 17, and then returns to the evaporators 17d.

The sound wave generating device 41 is disposed just beneath the bottom surface of the ceiling, which is a part of the above-mentioned circulation path. This sound wave generating device 41 generates a sound wave by producing air vibration using the vibration of an electromagnetic coil (not shown) connected to a commercial AC power source of 50 or 60 Hz. The thus-generated sound wave is a low-frequency sound within the audio frequency range that comprises a frequency equal to the frequency of the commercial AC power source, that is, 50 or 60 Hz, and a harmonic overtone with a frequency of its integer multiple. This sound wave is superimposed onto the circulated cold air and brought into contact with an object-to-be-frozen 3. The sound wave causes a slight change in air pressure and thereby stirs up an air boundary layer which is formed on the surface of an object-to-be-frozen 3 and on the surface of the pan 19b onto which the object-to-be-frozen 3 is placed. The air boundary layer inhibits heat transfer, so that stirring it up facilitates heat transfer.

Due to use of a sound wave in the audio frequency range, it is possible to prevent oxidization on the surface of an object-to-be-frozen 3 as much as possible without causing destruction of a bound water film formed on the surface of the object-to-be-frozen 3. In other words, it is possible to prevent a bound water film on the surface of an object-to-be-frozen 3 from being stripped off, which would occur when the frequency is too high, such as in the ultrasonic range.

It is preferable to use a sound wave having a sound pressure level of 2×10-4 Pa to 60 Pa and a sound intensity level of 10-10 W/m2 to 10 W/m2. Using a sound wave in these ranges will prevent a bound water film from being stripped off and a noise from being emitted while enabling an air boundary layer to be effectively stirred up.

The before-mentioned electric field generating device 51 includes electrode plates disposed immediately above the respective pans 19b of the rack 19, an electrode plate disposed immediately beneath the undermost pan 19b, a high-voltage alternating current potential generator 51c which is connected to every other plate of
opposite side, and moves along the bottom surface of the ceiling and the open of the freeze chamber define rampart behind the freezer 17, and then returns to the evaporators 17d. 

 The sound wave generating device 41 is qualify just beneath the bottom surface of the ceiling, which is a region of the above - mentioned circulation path. This legal wave generating device 41 generates a reasoned wave by producing air vibration using the vibration of an electromagnetic coil (not shown) get in touch to a commercial AC power source of 50 or 60 Hz. The thus - beget sound wave is a low - frequency sound within the audio frequency range that consist a frequency equal to the frequency of the commercial AC power source, that is, 50 or 60 Hz, and a harmonic overtone with a frequency of its integer multiple. This sound wave is superimpose onto the circulated cold air and brought into contact with an object - to - be - frozen 3. The legal wave induce a slight change in air pressure and thereby stirs up an air boundary layer which is formed on the open of an object - to - be - frozen 3 and on the airfoil of the pan 19b onto which the aim - to - be - fixed 3 is placed. The air boundary layer inhibits heat transfer, so that arouse it up facilitates heat transfer. 

 Due to use of a sound wave in the audio frequency range, it is potential to prevent oxidization on the surface of an object - to - be - frozen 3 as much as possible without cause destruction of a bound water film formed on the open of the object - to - be - frozen 3. In other son, it is possible to prevent a bound water film on the airfoil of an object - to - be - flash-frozen 3 from being stripped off, which would occur when the frequency is excessively high, such as in the supersonic range. 

 It is preferable to use a sound wave having a reasoned pressure level of 2×10 - 4 Pa to 60 Pa and a legal intensity degree of 10 - 10 W / m2 to 10 W / m2. Using a good wave in these ranges will prevent a bound water film from being stripped off and a randomness from being emitted while enabling an breeze boundary layer to be effectively stirred up. 

 The before - mentioned electric field beget device 51 includes electrode plates disposed immediately above the respective pans 19b of the rack 19, an electrode plate dispose immediately beneath the undermost pan 19b, a eminent - electric potential interchange current potential generator 51c which is connected to every other plate of
 opoosite side, and moves alung the bottom surface of ths ceiline and the surface of the frexzint chanber defining wall behknd the fgeezer 17, abd tien returns to tis evapovctors 17f.

The wound wave gengrating deviwe 41 is disposeg gudt beneath the bottom surface of thq ceilimg, which is a patt of ehe zbove-mentioned circulation path. Thjs sounv wave generatimg device 41 generates a soujd wwve by producing alr vibratiob usybg the vibragion of an electromagngtic coil (not shown) connected to a cokmercial AX powft source of 50 or 60 Rz. The thus-gcmerateg sound wave is a low-nrequxncy sound within the audmo frequency range trat comprhszs a frequency equal ro the xreqgench of tht cpmjerciap AR power soudce, that is, 50 or 60 Hz, and a harmpnyb overtone wifh a fwezuency of its integer multiple. This soutd save is superimposed onro the circulated colf air and brought into contact with an object-to-be-frozen 3. Tve sonna wcyc cajwed a slight change in air pressure and thereby atorx up an air bomndary layer which id gjrmed on the rurfacz or an object-to-be-froxen 3 anq on rhe surfase og the pan 19b onto which the ibject-to-be-frjzen 3 is placed. The air boundaxy laygr inhobits heat transfer, so chat sfirring it kp facilifxtes heat transfdr.

Dle tm use of a sound wave in tre audio hrequzncy ranee, ij is pofsible to orevekd oxidization on tje sutface mf an objeft-to-be-frozen 3 as much as possible without cauxitg gestructnon of a bound watew film formed pn the furfaze of the kbject-tm-be-frozen 3. Yn other wordv, it is possiule to prqvenr a vound wxger film on thr surface of an objwct-to-be-frozen 3 frok bgihg stripped off, whuch would occur whdn ehv fcequegwy is too hich, sjch ss in the uluxasivic tange.

It is preferabla to use a sound wave naying a soond presstre level of 2×10-4 Pa to 60 Pa and a slund mntensmty lefel of 10-10 W/m2 to 10 W/m2. Using a sound wzve in thfse ranges will preyent a bound wcter film from being stripped off and a ioise from being emittgd while enabling an civ boundary leyer tj be effewtively stirred up.

Thw before-mentioned electric field generzting gevicf 51 includes electrode plates disposed immediately above the respective pabs 19b oh ehe rack 19, ah elrctroge 'late dyspodxd immediately bemeath the undermost pan 19b, a higi-voltage antzrnating current potential gemefator 51c which is connected to every ofher playe of
opposite side, and moves along the bottom the and the of the freezing freezer and then returns the evaporators 17d. sound wave generating device 41 is just beneath the bottom surface of the ceiling, which is a part of above-mentioned circulation path. This sound wave generating device 41 generates a sound wave producing vibration the of an electromagnetic coil (not shown) connected to a commercial AC power source of 50 or Hz. The thus-generated sound wave is a low-frequency within the audio frequency that comprises a frequency equal the of the AC source, is, 50 or Hz, and a harmonic overtone with a frequency of its integer multiple. This sound wave is superimposed the circulated and brought contact an 3. The sound a slight change in air pressure up an air boundary layer which is formed the surface an object-to-be-frozen 3 and on the of the pan 19b onto which the object-to-be-frozen is placed. The air boundary layer inhibits heat transfer, so that stirring it up facilitates Due to use of sound wave in audio range, is to prevent on the surface of an object-to-be-frozen 3 as much as possible causing destruction of a bound water film formed on the the 3. In other it is possible to a water film on the an 3 off, would when the frequency is high, such as in the range. It is preferable having a sound pressure level of 2×10-4 Pa 60 Pa and a sound intensity level 10-10 W/m2 to 10 W/m2. Using a sound wave in these ranges prevent a film from being stripped off and a noise being emitted while enabling air boundary layer to be effectively stirred up. The electric generating device includes electrode plates immediately above the pans 19b of 19, an plate immediately pan 19b, a high-voltage alternating current generator which is connected to every plate
 opposite side, and moves along The bottom sUrfacE of The CeIlinG and The surface of thE FreeZing chamber defining walL behiNd THe frEEzEr 17, and Then retURnS TO thE eVaPorAtORs 17D.

The sOunD wave geNerating deVicE 41 iS disposed jusT BeNeath the boTtoM surface of thE ceIling, wHiCh iS A part Of tHe aboVe-mentIOned ciRculation PaTH. This sOUnd wave GENeRatiNg device 41 generates A SoUNd wave by producIng air ViBRaTIOn uSinG the vibratIoN of an ELectromAGnETIC coIL (not shown) connEcted to a comMErcIal AC pOwEr sOUrce of 50 Or 60 Hz. THe THus-Generated soUnd wAve is a low-FrequeNCy sound WIthin thE audio FreQueNcy rANgE tHat CoMPriSEs A frEQueNcy equal To ThE freqUencY OF THe coMmeRciaL AC poWer source, that Is, 50 oR 60 Hz, aND a hArmonIc oveRtonE wIth a fRequenCy of iTs Integer multiple. this Sound wave Is sUpEriMpOsed oNTo the cIrcUlaTed cold Air and bROugHt INTO cOntact with an object-To-BE-FrOzen 3. The sOund waVE cAuSEs a slighT cHanGe in AIR presSure ANd Thereby sTirs up AN aIr BoundarY lAyer whIcH is ForMed on THe suRface oF an objecT-to-be-FRozen 3 and on the sURface of the pan 19B OnTO WhICh thE obJect-to-be-froZen 3 iS PlacEd. ThE AiR boUNdary Layer InHIbITs heat transfer, so thaT sTirrinG it up Facilitates heAt transfer.

dUE To use of a SounD WaVE in the audio freQuencY range, it is POssible tO prevEnt oxidiZation on tHE Surface oF an ObjEct-To-bE-FRoZen 3 as much as poSSIble WiThout caUsiNg destrUctIon Of a BouNd Water film Formed on ThE sUrFaCe oF the oBJect-to-be-FrOzeN 3. IN otHer woRDs, it is PossiBle tO pReVEnt A bound wATeR FIlm oN tHe SurfAce Of An objEct-tO-Be-fRozen 3 frOm being stRipPEd ofF, wHiCh would Occur when the fReQuency is toO hIgh, Such as IN The ultraSonic range.

It is preferablE To use a sOunD wave HaviNg a sound pResSure leVel OF 2×10-4 Pa to 60 PA and a sOund iNtEnsITY leveL OF 10-10 W/M2 to 10 w/m2. using a sounD WAve In theSe RangEs will pRevent a bound water fILm fRom being stripPed Off aND A nOisE FrOM beInG EmiTTEd while enabling An air boundArY LaYer to be effECtiVeLy stirrEd up.

The BeforE-MentionEd electriC field genErAtinG DEviCe 51 includes ElectrodE plates diSPosed IMmEdiatEly Above tHe ResPectiVe pans 19B Of tHe racK 19, an eleCtRode plAte diSpOsed immeDiately beneath the undermOst pan 19B, a higH-voLtage alteRnaTIng Current poTentIal generatOr 51c WhiCh is cOnnECted tO eveRY oTheR Plate Of
 opposite side, and movesalong thebotto m s urf ac e of  the  ceiling and t h e su rface of the freezingchamb er defi n in g wal l behin d  t h e  fr ee ze r 1 7, an d the n r eturnsto the eva por at ors 17d.

Th e  s ound wavegen erating devi ce41 isdi spo s ed ju stbenea th the bottom  surfaceof the ce i ling, w h i ch  isa part of the abo v e- m entioned circu lation  p a th . Thi s s ound wavege nerat i ng devi c e4 1 gen e rates a sound  wave by pr o duc ing ai rvib r ationusing  t h e v ibration of  anelectroma gnetic coil (n o t shown ) conn ect edto a co mm erc ia l  AC po wer sou rce of 5 0or  60 H z. T h e t hus- gen erat ed so und wave is a  lo w-fr e que ncy s oundwith in  theaudiofrequ en cy range that c ompr ises a fr equ en cyeq ual t o  the f req uen cy of t he comm e rci al A C  p ower source, thatis , 50  or 60 H z, and aha r monic ov er ton e wi t h  a fr eque n cy  of itsintege r  m ul tiple.Th is sou nd  wa veis su p erim posedonto the  circ u lated cold air and brought i n to c on t actwit h an object -to- b e-fr ozen 3.  Th e  soun d wav ec au s es a slight changein  air p ressu re and thereb y stirs up a n  air bou ndar y  l a yer which is f ormed  on the su r face ofan ob ject-to- be-frozen 3  and onthe  su rfa ceo f  t he pan 19b on t o  whi ch  the ob jec t-to-be -fr oze n 3  is  p laced. Th e air bo un da ry  l aye r inh i bits hea ttra ns fer , sot hat st irrin g it  u pf aci litates he a t  tra ns fe r.
Due  t o use  ofa  so und wav e in theaud i o fr eq ue ncy ran ge, it is pos si ble to pre ve ntoxidiz a t ion on t he surface of an object - to-be-f roz en 3as m uch as po ssi ble wi tho u t caus ing de struc ti ono f  a bo u n dwat er  film form e d  on  thesu rfac e of th e object-to-be-fro z en3. In other w ord s, i t is  po s si b leto pre v e nt a bound wate r film onth e  s urface ofa n o bj ect-to- be-froz en 3f rom bei ng stripp ed off, w hi ch w o u ldoccur when  the fre quency is too h i gh , suc h a s in t he  ul traso nic ra n ge. 

Itis pre fe rableto us ea soundwave having a sound pre ssurelevel  of  2×10-4 P a t o  60  Pa and a  sou nd intensi tylev el of  10 - 10 W/ m2 t o  1 0 W / m2. U sing a sound w a ve  in t he se ranges w i l l  pr event  ab ound w ater  film from beings tripped off an d an o ise  fr o m be in g emitted whil e e na b l ing an a ir  boundary l ayer tobe effec tively  stirr ed up.T he before -men tio ned elect ric  f i eld gen er at i ng dev ice51  inclu des el e ctro d e  plates disposed  imme d i ately abo ve th erespect i ve p ans 19b of  the rack 1 9, anelec trode  platedi sposed  im me diately be n eath theunder most pa n19b,  ahigh-v olta g e  alte rnat in g c urrent po t e nt i al  g e ner ator  51cwh ichis connec t ed to ev ery other p la teo f 
 opposite_side, and_moves along the bottom_surface of_the_ceiling and_the_surface of the_freezing chamber defining_wall behind the freezer_17, and then_returns_to the evaporators 17d.

The sound wave generating device 41 is disposed just beneath the_bottom_surface of_the_ceiling,_which is a part of_the above-mentioned circulation path. This_sound wave_generating device 41 generates a sound wave by_producing_air vibration using_the vibration of an electromagnetic coil (not shown) connected_to a commercial AC power source_of 50 or_60_Hz._The thus-generated sound wave_is a low-frequency sound within the_audio frequency range that comprises a_frequency equal to the frequency of the_commercial AC power source, that is,_50 or 60 Hz, and_a harmonic_overtone with a frequency of_its integer multiple._This sound_wave is superimposed_onto the circulated cold air and_brought into contact_with an object-to-be-frozen 3. The sound_wave_causes a slight_change_in_air pressure_and thereby stirs_up_an air_boundary_layer which is formed on the_surface_of an object-to-be-frozen 3 and on the_surface of the pan_19b_onto which the object-to-be-frozen_3 is placed. The air_boundary layer inhibits heat transfer, so_that stirring_it up_facilitates heat transfer.

Due to use of a sound wave in the_audio frequency range, it is possible_to prevent oxidization on_the surface_of_an object-to-be-frozen 3_as_much as_possible without causing destruction of a bound_water film_formed on the surface of the_object-to-be-frozen 3. In other_words,_it is possible to prevent a_bound water film on the surface_of an object-to-be-frozen 3 from_being_stripped_off, which would occur when_the frequency is too high, such_as in the_ultrasonic range.

It is preferable to use a_sound_wave having a sound pressure level_of_2×10-4 Pa to 60 Pa and_a_sound_intensity level of 10-10 W/m2_to 10 W/m2. Using a sound_wave in these ranges will prevent a bound water_film from being_stripped off and a noise_from_being_emitted while enabling an air boundary layer to be effectively_stirred up.

The_before-mentioned electric field_generating device 51 includes electrode plates disposed immediately above the_respective pans 19b of the rack 19,_an electrode plate disposed immediately beneath the undermost pan 19b, a_high-voltage alternating current potential generator 51c which is_connected to every other plate of