Spray evaporation heat transfer of R-141b on a horizontal tube bundle

Optimal nozzle spray cone angle for triangular-pitch shell-and-tube interior spray evaporator

“…5). Data sampling was delayed until the system attained steady-state conditions (i.e., a variation in the system saturation temperature of less than 0.1°C/ min [18,19]). Moreover, to minimize the effect of experimental fluctuations, each data point was obtained by averaging a minimum of 20 data-acquisition scans.…”

“…1), and hence the cooling effect was reduced. Chang and Chiou [19] devised a technique for enhancing the heat transfer performance of spray evaporators by fitting a liquid collector to the underside of each tube in the bundle. The experimental results showed that the liquid collectors prevented the onset of the dry-out phenomenon and therefore resulted in a significant improvement in the heat transfer coefficients of the lower tubes.…”

Falling-film evaporation on horizontal tubes—a critical review

“…For R-123 and low heat fluxes, the surface Turbo-B gives the highest performance at the lowest row [68]. Some methods have been proposed to avoid partial dryout on the lower rows [71,72]. By adding spray tubes at the center of the bundle, Tatara and Payvar [72] found an increase in the thermal performance, relative to a configuration that used only liquid drip tubes above the tube bundle; they also found, a reduction in the overfeed rate for a similar global h. Chang and Chiou [71] added liquid collectors to the bottom of the tubes and thus reduced the difference in the local h along the bundle depth.…”

“…Similar to [67] 20 Tubes in 4 vertical rows; triangularpitch/plain tube, GEWA-SC, Turbo-B, finned tube (1575 fins/m)/D ext Z 19 mm/copper [70] Ammonia Standard-and wide-angle commercial round full-cone nozzles; distances between nozzles and tubes of 50.8 and 102 mm 3 by 3 square pitch/D ext Z19.1 mm/ stainless steel [71] R-141b Full cone circular spray nozzles with an orifice diameter of 2 mm 5 Tubes in a triangular-pitch arrangement with 2 horizontal rows/plain tubes with and without a peripheral liquid collector/D ext Z19 mm/copper [72] R-11 A tube with holes at its bottom above each column, and two tubes with holes on their surfaces positioned in the third horizontal row 36 Tubes (1024 fins/m) in 5 horizontal rows; triangular-pitch arrangement/ D ext Z19.1 mm/R-11 vapor in countercurrent flow [73,74] Ammonia Standard-(orifice DZ4.76 mm/spray angle 908) and wide-angle (orifice DZ 3.99 mm/spray angle 1108) commercial round full-cone nozzles; distance between nozzles and tubes up to 150 mm 3-2-3 triangular-pitch/D ext Z19 mm/ stainless steel [75] Water Similar to [36] 3 Horizontal tubes vertically aligned/ D ext Z13, 20, and 30 mm/copper a When not specified, consider the experiments as conducted solely for plain tubes.…”

Heat transfer enhancement of falling film evaporation on a horizontal tube bundle

“…It should be noted that in the present study the liquid sheet falling between horizontal tubes mode is considered. The spray cooling heat exchanger was studied numerically and experimentally by Negeed [3] . He studied the effect of the operating conditions of the heat transfer effectiveness for the horizontal tube bundle and the tubes were arranged as inline.…”