The experiment of spray evaporation of ammonia was conducted using spray nozzles distributing liquid ammonia downward onto a horizontal, 3-2-3 triangular-pitch plain-tube bundle. Heat transfer performance of individual tubes in the tube bundle was studied by changing saturation temperature, heat flux, spray flow rate, nozzle height, and nozzle type. The present data suggest that the tube bundle effect is less significant at a lower saturation temperature, a lower spray flow rate, a smaller nozzle height, and with standard-angle compared with wide-angle nozzles. Mechanism causing variation of individual tubes' heat transfer performance was studied. Results were compared with ammonia spray evaporation in a square-pitch plain-tube bundle.