TEMPERATURE FIELD FROM FREE TWO PHASE JET USING INFRARED EQUIPMENT

Autor/autori: Alexandru CHISACOF, Sorin DIMITRIU, Cristian DRAGOSTIN

Rezumat: Lucrarea trateaza utilizarea metodei de analiza in infrarosu a campului de temperaturi dintr-un jet de ceata de apa. Elemente privind erorile de masurare a temperaturii in infrarosu, comparativ cu metodele de masurare directa, sunt prezentate in lucrare. Ca rezultat al acestui mod de evaluare a radiatiei s-a obtinut caracteristica de emisivitate a mediului. A fost pusa in evidenta influenta temperaturii, a umiditatii relative precum si a grosimii stratului dintre camera si obiectul vizat. Pe aceasta baza s-au obtinut parametrii de setare a camerei in functie de proprietatile mediului. Testele au fost realizate pe un jet cald de lichid in evaporare, generat de un ajutaj convergent. Principala concluzie a lucrarii o constituie faptul ca metoda de masurare a temperaturii in infrarosu trebuie corectata pe baza valorilor obtinute prin masuratorile directe, in special in cazul mediului cu ceata. Pe aceasta baza calculul fluxurilor de energie schimbate de obiectele sau mediile supuse analizei sunt mai precise.

Cuvinte cheie: metoda infrarosu; jet bifazic; erori de temperatura; evaluarea energiei

Abstract: The paper treats the use of infrared method in aim to evaluate the temperature field in water mist jet. The elements concerning the errors of temperature measurement due to the infrared method in comparison with direct contact method are shown. As the result of this assessment the radiation emission of analysed structure was found. Also, the influence of the depth of the air-fog layer and of the relative humidity is analyzed. The results show that an assessment of a field temperature, using infrared method, requires the adequate correction of the red values on the apparatus screen. These findings explain why there are a lot of inadequate values if the preset emission factor does not take into consideration the environmental two-phase composition and distance between the infrared camera and the main target. The tests were realised on the water mist jet is created from plain water, forced in special nozzles. The main conclusion of the paper resides in the fact that the infrared method must be used with the specific corrections of temperature values based on the direct measurement. On this way the calculated heat fluxes and the energy assessment of the subjected equipment are more accurate.

Keywords: infrared method; two-phase jet; temperature errors; energy assessment.

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