Uncertainties in transient heat transfer measurements with liquid crystal

✍ Scribed by Youyou Yan; J.Michael Owen

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 171 KB
• Volume: 23
• Category: Article
• ISSN: 0142-727X
• DOI: 10.1016/s0142-727x(01)00125-4

✦ Synopsis

Thermochromic liquid crystal (TLC) is used extensively as an experimental tool to determine heat transfer coefficients. In a transient experiment, if the time at which the TLC changes colour is known, then h, the heat transfer coefficient, can be found from the solution of the so-called semi-infinite-plate problem. If T aw , the adiabatic-wall temperature, is unknown, then two narrow-band TLCs can be used to determine both h and T aw . In this paper, an uncertainty analysis is used to calculate P h , the uncertainty in h, and P Taw , the uncertainty in T aw (when T aw is unknown), in terms of the random uncertainties in the measured temperatures. Computed values, obtained using a Monte Carlo method, are in good agreement with the uncertainties obtained from the analysis. It is also shown how the uncertainties P h and P Taw can be minimised by selecting the appropriate ranges of TLC. Conversely, a poor choice of TLC can result in large values of these uncertainties.