In this study, a model of a binary geothermal power plant has been developed in Aspen software and validated with the real data from Chena binary geothermal power plant. The validated model is used to investigate the effect of heat exchanger design on Return on Investment (ROI) of the plant. The analyses include type selection and sizing of heat exchangers as well as the possibility of using a recuperator in the system. The choice of heat exchanger type was found to significantly influence the ROI of the plant. The base case studied here uses shell and tube (S&T) type. The highest ROI of the plant was obtained with plate (PL) type for both heat exchangers where the ROI increases from 0.737 to 1.107. The possible sizes of heat exchanger design have been analyzed. The existing heat exchangers were found to already be sized to achieve an optimal ROI of 0.737 with net design power output at 210 kW. Reducing heat exchanger size increases the ROI by only about 2.59%, while reducing the net power output from 210kW to 203.9 kW. The design with maximum size of heat exchangers increases the net power output to 220.3 kW, but the ROI drops significantly by about 17%. Investigation into the addition of a recuperator to the system indicates that it could increase the net power output by about 1 kW. The system with a recuperator was found to have a superior thermal efficiency of 8.41%, but a low ROI of 0.409.