Question

9-24 An ASTM F441 chlorinated polyvinyl chloride (CPVC) tube is embedded in a vertical concrete wall (k = 1.4 W/m.K). The wall has a height of 1 m, and one surface of the wall is subjected to convection with hot air at 140°C. The distance measured from the plate's surface that is exposed to the hot air to the tube surface is d= 3 cm. The ASME Code for Process Piping limits the maximum use tem- perature for ASTM F441 CPVC tube to 93.3°C (ASME B31.3- 2014, Table B-1). If the concrete surface that is exposed to the hot air is at 100°C, would the CPVC tube embedded in the wall still comply with the ASME code? Hot quiescence air, T. Concrete wall Tube FIGURE P9-24

Answer 1

ANSWER:-

Given that

the wall has n height of 1 m

the tube surface d=3

k d Hot quiescence air. Too Conte wat Tube There is no contact resistance blw the core. Tube and concrete block. convective be heat transfer is pur free. connection. 0.03m 15 100-1400, Film Temperature Tt TS + Too = 100 +140 120 2011 > 120 - 126

The properties of air at 128e are. ka -0.033 W/mK 8=0.89191 m, V-252876 mis - -2544 KIDK If + 273 can Grushoff number: Go - 2298 (Ts-tos V2 119.81) (2.544 xio) (46) (2.52 x 105) 2 1.571 Xid 6. PY - Ill X10 Thus using correlation. BL 01 (Go.poj 3 ka 0.18 0.033 Chilli x10973 5 = 3.41 Wim? K. Now under steady state heat transter heat. conduction in concrete block. - heat convection from outer in surface.

at should be noted that "A" is crow section area of concrete block. heal transfer by convertion takes place through- same area. TS-It -- ha (Too-TS) KA It= 1, [ 10.08) (Too-TS). it = 97.6776 Temperature of tube surface 97.077°C > 93.3°C. Thus it will not comply with Asont code.