tailieunhanh - Evaporation Condensation and Heat transfer Part 8

Tham khảo tài liệu 'evaporation condensation and heat transfer part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 270 Evaporation Condensation and Heat Transfer and dividing Eq. 26 by mscps j we have Ts i 1 1 1 2 sj - 2 1 ai 2 N S - 2 7 T 1 . AỈ 27 where Q1 Lx N - the mesh rthe tube length. The energy conservation principle for the flue gas applied for the finite control volume Fig. 5 is Ơ 2V n hgp Tw3f 28 After rearranging Eq. 28 we obtain T T 2 wgcpgji rgjia Azhg T 3 i 29 where the mesh outer surfaceof deposits is Fig. 6 OA n 2r0 2Oz ax. 30 The flue gas average specific heatet constant pressure is given by Fig. 5. Finite volume for energy balance on the steam and gas sides a and in-line array of superheater tubes b . Numerical Modeling of Cross-Flow Tube Heat Exchangers with Complex Flow Arrangements 271 Equation 29 can be written as _Ị_ D sW hgOAz Omgcpgìiẵ tig AzTu 3ị 32 Introducing the mesh number of transfer units for the gas h 2h DAz ŨN . r g . g 2 Dm c ỗ rỗ Ỗ1 rỗ Ỗ1 33 and dividing Eq. 33 by mgcpgi we obtain 1 2 g 1 ai 2 g- 2 T i N 1 w3i g-i 2 i 34 1 . ẠỈ. Subsequently energy conservation equations fcr the tube wall Fig. 6 will be written. Fig. 6. Tube wall with a layer of de posits at the outer tube surfaces. The tube wall and the deposit layer are divided into three finite volumes Fig. 7 . Energy conservation equations may be written as node 1 Ỉ It oT nri l a Ta 1 Tf 2 a 2 ã 1 -7 J - n T ã T 1 Da 55--------------------- - Ũd 0 35 b y b J c LU I jC Ị Clt 2 ỵ J c 1