Uporedna dinamička analiza posebnih tipova razmenjivača toplote
Comparative dynamic analysis of special types of heat exchangers
Author
Sićović, AleksandarMentor
Debeljković, DragutinCommittee members
Milinović, MomčiloCrnojević, Cvetko
Stevanović, Vladimir
Šekara, Tomislav
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Show full item recordAbstract
Predmet ove doktorske disertacije su teorijska i eksperimentalna istraživanja u vezi sa
dinamičkim ponašanjem savremenih kriogenih razmenjivača toplote poznatih kao Džul-
Tomsonovi minihladnjaci. Istraživanje je usmereno na komponente glave za samonavođenje kao
i druge IC tipove senzora za jednokratnu upotrebu. U skladu sa realnim kao i uvek
osavremenjenim novim zahtevima funkcionisanja razmenjivača toplote i njegovih ciljnih
funkcija i ponekad suprotnih projektnih zahteva razmatrano je njihovo ponašanje sa aspekta
termodinamike, gasodinamike kao i sa aspekta razmene toplote i mase. Razmatran je realan gas
kao rashlađivač sa posebnom pažnjom na osnovna termodinamička svojstva sadržana u Džul
Tomsonovom koeficijentu kao i prilagođenim jednačinama idealnoh na realni gas primenjenih na
konstrukciju minihladnjaka i njegovo optimalno usaglašavanje. Promene gustine realnih gasova,
u odnosu na pritisak i stepen suvoće ekskluzivno oko jedinice je bilo oformljeno kao i teoretski
izraz za trenje... kod realnih gasova. Rad takođe razmatra potpuni cikjus od izvora rashlađivača do
korisnika rashlađivača (IC detektora) kao i optimizacije razmene toplote i mase do zahtevanih
temperature detektora. Eksperimentalna instalacija je dodatno projektovana i testirana kao
univerzalna oprema za projektne varijacije kao i promociju i utvrđivanje novih koncepata Džul
Tomsonovih minihladnjaka. Automatsko upravljanje je dodata kao poseban deo ovog rada.
Nelinearan matematički model je linearizovan za rashladni process u posmatranom kriogenom
razmenjivaču toplote i ultimativno razmatran jednačinama prostora stanja i izraženim kvazi
stacionarnim numeričkim vrednostima. Rad nudi rešenja za poboljšanje neregulisanih kriogenih
mini hladnjaka i nove savremene delimično ili potpuno regulisane sa istim ili sličnim
konstrukcijom.
Rad razmatra frekventni impulsni tip upravljanja procesom hlađenja spregnut sa
nestacionarnom termodinamikom kriogenih minihladnjaka. Istraživanje uključuje novi
fenomenološki pristup na bazi karakterističnog vremena gasodinamičkog sistema, primenjen na
ovu vrstu regulacije. Takođe je razvijen i novi sistem upravljanja sastavljen od klasičnog PID
regulatora sa pridodeljenom posebno razvijenim PWM kontrolerom na bazi diskretno impulsnog
modela upravljanja. Teorijski pristup je razrađen i za definisanje graničnog kapaciteta izvora
rashlađivača vezanu sa frekvetnu karakteristiku regulatora.
Novi tipovi Džul Tomsonovih minihladnjaka integrisani u ovom radu zadovoljavaju širok
spektar temperaturske regulacije i usmeravaju na dalja istraživanja u ovoj oblasti.
The subject of the PhD thesis is the theoretical and experimental research related to the
dynamic behaviour of modern cryogenic heat exchangers known as the Joule-Thomson
minicoolers. Research is orientated to the IR homing head components as well as the other IR
cooling types of sensors for the particular single operation. According to the real as well as
always advancing requirements, of the heat exchanger operation and aimed function, sometimes
opposite in design demands, their behaviour is considered thermodynamically, gasdynamically
and from the heat and mass transfer point of view. The real gases as the coolants are considered
with pointed out consideration of the fundamental thermodinamically capability content in to the
Joule Thomson coefficient as well as adopted equations of ideal to real gases employed on the
minicooler design and its optimal consideration. Changes of density of real gases, related to the
pressure and the degree of humidity exclusively about one value was fo...rmed as well as the
theoretical expression to explain the real gas friction. Paper also considered full cycle of coolant
source to the coolant consumer (IR detector) and heat and mass transfer optimizing according to
detector temperature requirements. Exsperimental set up is additinally designed and tested as
universal equipment for the design variation as well as promoted and maturated new concepts of
Joule Thomson mini coolers. Automatic control is contributed as the special part considered in
this paper. Nonlinear mathematical model of coolant flow process is made as the linear in the
observed cryogenic heat exchanger and ultimately led as space of state equations, expressed by
numerical values for quasi-steady state operating regimes. Paper offer solution for upgrading of
unregulated cryogenic mini-cooler into the new, improved type, partially or fully regulated, with
the same or similar design.
Paper considered the frequency pulse-type of cooling process control coupled with the
unsteady thermodynamics cryogenic minicooler. Research involved the new phenomenological
approach based on the analysis of the characteristic time of the gas dynamic system, to employ
this type of regulation. A new type of control system was also developed, composed of a
classical PID regulator, associated with the developed PWM-control unit based on the discretely
(pulse) control known in literature as the width amplitude modulation. The theoretical approach
is done regarding threshold capacity of coolant source as the relation to the frequent
characteristics.
The new types of Joule-Thomson minicoolers integrated in this paper satisfies a wider
spectra of temperature control and orientated to the further research in this area.