8.18. Consider the thermometer-shield arrangement shown in Fig. 8.32. Assuming that the shield area is very large compared with the thermometer area and that all radiation leaving the thermometer is intercepted by the shield, calculate the true gas temperature using the following data: h, = 2.0 Btu/h . ft?: °F h, = 1.5 Btu/h - ft?. 'F E = 0.8 . Es = 0.2 T= 600°F T; = 100°F (It is assumed from the statement of the problem that Fis = 1.0, Fse = 1.0, and Fte = 0.) What temperature would the thermometer indicate if the shield were removed? Calculate the error reduction owing to the use of the radiation shield.