Question

A shell and tube heat exchanger with one shell pass and one tube pass will be used to condense the steam to saturated liquid, which enters the shell side as a saturated vapor at 400 K. The tube side contains R-134a refrigerant with an inlet temperature of 300 K and a mean velocity of 0.4 m/s. The steam flow rate is 1.5 kg/s. The tubes are made from AISI 302 stainless steel and have a 1" nominal diameter (Di = 26.6 mm and Do = 33.4 mm). The heat transfer coefficient at the outer surface of the tubes is ho = 10,000 W/m^2K. Assume a fouling resistance of 0.0002 m^2K/W at the inside surface of the tubes and negligible fouling at the outside.

a) If the coolant outlet temperature is not to exceed 320 K, what is the minimum allowable coolant flowrate?

b) How many tubes are required to achieve the desired performance?

c) What tube length is required?

Answer 1

r o They One sheld one tube pass pass - I - to > THA UTIZOS satunded rapon = 4ook shell side Tube side R-1349 > Tci = 300k Tco=3204 ů z 0.4 mis mis = 1.5 ngis ho= 18,000 w/mk Dis 266mm) = 26.6x173 m Do = 33.4 mm = 33.4 X163 m ma R biz 0.0002 makler K= 16.2 W Tube side . (p=1485.15 - Tmz 300+320 2310n , preopenty of R-1340 of 310k - ezitãoug lon3, 120.0413mm M2 1+127x104 Kolms , pr=3.31 a - 1160X. 4 x 26.6x10s Reda eV Di u 7.727 x 164 Redz 21467 > 4000 flow is fun bulent.

0.4 K for Turbulent flow inside Tube: Nu = 0.023 Red piz" í oftar Beelter Nuz hidi 20.023 (714678331,4% -ezedsion) l'n='3 ccooling) hidi = 283.78 n.4 Cheeling Қ 2) hi 283.78 y 0.0773 - = 824.6 White 26.6x103 The overall inside heo transten co-elficient base Uiz + R* ) i ho El + Bli Boho - Qiz - otot.0 2 + 26 mg f 0092f 2 L 6246 en content - 2x 16.2 via 1824.67.00027 0.000186 + (49842105) Viz 595.8 clith U VEZI I

1) a= mcpAT Qzi hay 3) 1.5x2138 2 9 X 1485*C 3280300) 6922183 kJ z) M = 107.augls can) of 4ook 1. * Reborigeran How Log mean Tempererne Ditterrence?- A Teme Tp = 100-80 Yogh un ( 100/80) 41, 2801 422too = 89.6°C 320 300 Q- Ui A; 4im e) 1:5X21382 595.88103 x Ai x 89-6 =) Aiz Go.of m2 m= e Av Nottubes /penpos 10495 1160 x 774 X226610072x0.4 XN e) N = 418.6 ~ 419 cale of tabe) 11) a) Az à di Lw 34 69.00 / C8X (26611900) X 419