The heat exchanger is major element as far as heat transfer and energy conservation is concern. There are so many types of heat exchangers available but due to wide range of design possibilities, simple manufacturing, low maintenance cost, cross flow and counter flow heat exchanger extensively used in petroleum, petrochemical , air conditioning, food storage and other industries. The shell and tube heat exchanger is widely used in industries as a chiller plant for transfer waste heat from the injection molding machine to the cooling water for improve the efficiency of the injection molding machine. The transformations of the waste heat from the injection molding machine to the cooling water are dependent on the heat exchange capacity of heat exchangers. To increase the heat exchange capacity of heat exchanger optimization is done which seeks to identify the best parameter combination of heat exchangers. Nine models are made on the basis of taguchi method in NX 10.00 and CFX analysis is carried out in ANSYS 14.5. Result obtained from that gives the best dimension of heat exchanger for minimum outlet temperature of water.