An analytically based computer program was used to calculate the performance benefits provided by the use of enhanced tube geometries in an R-11 flooded refrigerant evaporator. Three different boiling surface geometries are evaluated: integral fins, and two different high-performance enhanced boiling surface geometries. Four water-side surface geometries are evaluated: a plain surface, a 10-ridge ribbed tube, a 30-ridge ribbed tube, and a corrugated tube. The performance analysis is applied to a 250-ton (879-kW) R-11 chiller operating at full load condition. The reference evaporator bundle has 180 tubes 135 in. (3.43 m7rpar; long, with two water-side passes. The analysis compares the performance benefits provided by the enhanced boiling surface with a plain internal diameter (ID7rpar; and with an enhanced ID. Analysis are provided to define the shell length reduction for specified operating conditions, and to define how much the saturation temperature may be increased for a bundle of fixed size. Analysis is also provided to determine the benefits provided by introducing the flash gas to the evaporator, and to determine the preferred bundle aspect ratio.