Izgradnja in testiranje sistema za hitro umerjanje merilnikov nizkih temperatur rosišča

Kramer, Gregor (avtor), Hudoklin, Domen (mentor)

Natančno merjenje in nadzor vlage v plinih sta ključnega pomena v industrijskih procesih, kot sta proizvodnja polprevodnikov in tehničnih plinov, kjer nizka vsebnost vodne pare neposredno vpliva na kakovost in zanesljivost izdelkov. Obstoječi sistemi za umerjanje vlagomerov so sicer zelo natančni, vendar je njihova uporaba pri zelo nizkih vsebnostih vodne pare pogosto časovno zahtevna, saj je sušenje sistema zaradi desorpcije vode z notranjih površin zelo počasno. Namen diplomskega dela je zasnova in izdelava sistema, pri katerem bi bilo mogoče čas umerjanja skrajšati. V delu so najprej predstavljene osnove higrometrije ter ključne merilne veličine za opisovanje vsebnosti vodne pare v plinih, in sicer relativna in absolutna vlažnost, volumska koncentracija, specifična vlažnost ter rosišče. Sledi pregled vlagomerov, ki se uporabljajo za merjenje nizkih vsebnosti vodne pare – spektroskopskih, kapacitivnih in rosiščnih – skupaj z njihovimi merilnimi principi, prednostmi in slabostmi. Na podlagi pregleda obstoječih tehnologij je bil zasnovan in izdelan sistem za umerjanje vlagomerov. Sistem kot nosilni plin uporablja visoko čist dušik (> 99,999 %), ki pred vstopom v celico za umerjanje, izdelano iz nerjavnega jekla 316L, prehaja skozi filter, ki deluje kot molekularno sito. V celici je nameščena zamenljiva permeacijska cevka iz poliamida (PA), rosišče plina na izhodu sistema pa meri rosiščni vlagomer MBW 373LX. Delovanje sistema je bilo ovrednoteno s štiridnevno neprekinjeno meritvijo temperature rosišča na izhodu sistema. Meritev je bila razdeljena na dva dela: permeacijska cevka je bila ob začetku prazna, zato se je sistem najprej samo sušil, temperatura rosišča je v 52 h padla z −2,7 °C na −62,1 °C. Ob doseženi najnižji vrednosti je bila v cevko vnesena voda, kar je povzročilo naraščanje temperature rosišča do −53,7 °C ob koncu meritve. Meritev je pokazala, da je sušenje sistema počasno in zahteva več kot dva dni neprekinjenega obratovanja, medtem ko se je sistem po vnosu vode novi delovni točki približal v približno desetih urah. Vzpostavitev delovne točke je torej hitrejša od sušenja, kar omogoča hitro preklapljanje med delovnimi točkami z več vzporedno nameščenimi permeacijskimi cevkami, sušenje bi bilo potrebno le ob prvi vzpostavitvi sistema.

• Jezik: Slovenski jezik
• Ključne besede: higrometrija, umerjanje vlagomerov, rosišče, permeacijske cevke, generator vlage
• Vrsta gradiva: Diplomsko delo/naloga
• Organizacija: FE - Fakulteta za elektrotehniko
• Leto izida: 2026
• PID: 20.500.12556/RUL-188331
• Datum objave v RUL: 21.09.2026

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Development and testing of a system for rapid calibration of low dew-point hygrometers

Izvleček

Accurate measurement and control of moisture in gases are essential in industrial processes such as semiconductor manufacturing and technical gas production, where low water vapour content directly affects product quality and reliability. Existing systems for calibrating hygrometers are highly accurate but are often too slow under ultra-dry gas conditions, as drying the system is very slow due to the desorption of water from internal surfaces. The aim of this thesis is to design and construct a system that could shorten the time required for hygrometer calibration. The thesis first introduces the fundamentals of hygrometry and the key quantities used to describe water vapour content in gases, namely relative and absolute humidity, volumetric concentration, specific humidity, and dew point. This is followed by an overview of hygrometers used for measuring low water vapour concentrations, including spectroscopic, capacitive, and chilled-mirror types, together with their measurement principles, advantages, and limitations. Based on the reviewed technologies, a hygrometer calibration system was designed and constructed. The system uses high-purity nitrogen (5.0N) as a carrier gas, which passes through a molecular-sieve filter before entering a calibration cell made of 316L stainless steel. An exchangeable permeation tube made of polyamide (PA) is installed inside the cell, while the dew point of the gas at the system outlet is measured using an MBW 373LX dew-point hygrometer. The performance of the system was evaluated by a continuous four-day measurement of the dew point at the system outlet. The measurement consisted of two consecutive parts. The permeation tube was empty at the start, so the system was first only drying, and the dew point fell from −2.7 °C to −62.1 °C over 52 h. Once this minimum was reached, water was introduced into the tube, which caused the dew point to rise to −53.7 °C by the end of the measurement. The measurement showed that drying the system is slow and requires more than two days of continuous operation, whereas after the water was introduced the system approached its new operating point within about ten hours. Establishing an operating point is therefore faster than drying the system, which enables rapid switching between operating points using several permeation tubes installed in parallel, drying would be required only when the system is first brought into operation.

• Ključne besede: hygrometry, hygrometer calibration, dew point, permeation tubes, humidity generator