Reduction of dynamic error in measurements of transient fluid temperature

• Autorzy: Jaremkiewicz M.
• Języki publikacji: EN

Abstrakty

EN

Under steady-state conditions when fluid temperature is constant, temperature measurement can be accomplished with high degree of accuracy owing to the absence of damping and time lag. However, when fluid temperature varies rapidly, for example, during start-up, appreciable differences occur between the actual and measured fluid temperature. These differences occur because it takes time for heat to transfer through the heavy thermometer pocket to the thermocouple. In this paper, a method for determinig transient fluid temperature based on the first-order thermometer model is presented. Fluid temperature is determined using a thermometer, which is suddenly immersed into boiling water. Next, the time constant is defined as a function of fluid velocity for four sheated thermocouples with different diameters. To demonstrate the applicability of the presented method to actual data where air velocity varies, the temperature of air is estimated based on measurements carried out by three thermocouples with different outer diameters. Lastly, the time constant is presented as a function of fluid velocity and outer diameter of thermocouple.

Słowa kluczowe

EN

first-order model; temperature measurement; time constant; transient conditions; uncertainty analysis

PL

analiza niepewności; model pierwszego obiektu; pomiar temperatury; stała czasowa; warunki przejściowe

• Wydawca: Wydawnictwo Instytutu Maszyn Przepływowych PAN ; Komitet Termodynamiki i Spalania PAN
• Czasopismo: Archives of Thermodynamics
• Rocznik: 2011
• Tom: Vol. 32, no. 4
• Strony: 55--66
• Opis fizyczny: Bibliogr. 20 poz.,

Twórcy

autor

Jaremkiewicz M.

• Cracow University of Technology, Department of Thermal Power Engineering, al. Jana Pawła II 37, 31-864 Kraków, Poland,

Bibliografia

• [1] NICHOLAS J.V., WHITE D.R.: Traceable Temperatures. An Introduction to Temperature Measurement and Calibration, 2nd edn. Wiley, New York 2001, 140–145.
• [2] MICHALSKI L., ECKERSDORF K., MCGHEE J.: Temperature Measurement, Wiley, Chichester 1991.
• [3] WIŚNIEWSKi S.: Temperature Measurement in Engines and Thermal Facilities, WNT, Warszawa 1983 (in Polish).
• [4] TALER J.: Theory and Practice of Identification of Heat Transfer Processes. Zakład Narodowy imienia Ossolińskich, Wrocław 1995 (in Polish).
• [5] KABZA Z., KOSTYRKO K., ZATOR S., ŁOBZOWSKI A., SZKOLNIKOWSKI W.: Room Climate Control, Agenda Wydawnicza, Pomiary Automatyka Kontrola, Warszawa 2005 (in Polish).
• [6] LITTLER D. J., et al.: Instrumentation, Controls & Testing. Modern Power Station Practice. Pergamon Press, Oxford 1991.
• [7] CHILDS P.R.N.: Practical Temperature Measurement, Buterworth-Heinemann, Oxford 2001.
• [8] GERASHCHENKO O.A., GORDOV A.N., LAKH V.I., STADNYK B.I., YARYSHEV N.A.: Temperature Measurements. Naukova Dumka, Kiev 1984 (in Russian).
• [9] JE-CHIN HAN, SANDIP DUTTA, SRINATH V.EKKAD: Gas Turbine Heat Transfer and Cooling Technology, Chapter 6, Experimental Methods, Taylor&Francis, New York, London 2000, 531–584.
• [10] SZÉKELY V., RESS S., POPPE A., TÖRÖK S., MAGYARI D., BENEDEK ZS., TORKI K., COURTOIS B., RENCZ M.: New approaches in the transient thermal measurements. Microelectronics J. 31(2000), 727–733.
• [11] CROCKER D.S., PARANG M.: Unsteady temperature measurement in an enclosed thermoconvectively heated air. Int. Comm. Heat Mass Transfer 28(2001), 1015–1024.
• [12] PAO C. CHAU: Process control, A First Course with MATLAB. Cambridge University Press, Cambridge 2002.
• [13] JAREMKIEWICZ M., TALER D., SOBOTA T.: Measurement of transient fluid temperature in installations of power plants. Pomiary Automatyka Kontrola 55(2009), 288–291.
• [14] ASME: Policy on reporting uncertainties in experimental measurements and results. J. Heat Transfer 122(2000), 411–413.
• [15] MOFFAT R.J.: Describing the uncertainties in experimental results. Experimental Thermal and Fluid Science 1(1988), 3–17.
• [16] TableCurve 2D v.5.0, Automated Curve Fitting & Equation Discovery. AISN Software Inc., 2000.
• [17] WT4401-S & WT4401-D Benchtop Wind Tunnels. Omega, Stamford, CT, USA, www.omega.com
• [18] SANITJAI S., GOLDSTEIN R.J.: Forced convection heat transfer from a circular cylinder in crossflow to air and liquids. Int. J. of Heat and Mass Transfer 47(2004), 4795–4805.
• [19] TALER D.: The Dynamics of Tubular Heat Exchangers. Uczelniane Wydawnictwa Naukowo-Dydaktyczne AGH, Cracow 2009 (in Polish).
• [20] TableCurve 3D v.4.0. SYSTAT Software Inc., 1993–2002.