Heat exchangers are widely used in industries where heat needs to be transferred from one fluid to another fluid. For example, there are plate-fin heat exchangers in gas turbine engines, shell and tube heat exchangers in oil refineries and tube bundle heat exchangers in domestic boilers. Among the different types of exchangers, tube bundle exchangers are the most commonly used heat exchange equipments. In this paper, heat exchanger with the structure of tube rows with bias flow and possible acoustic interaction at the tube row is studied for the acoustic reflection and transmission. The numerical methodology solving the linearized Navier-Stokes equation in the frequency domain is used. It has the advantage of taking into account the flow effects, viscous losses as well as thermal losses in the acoustic propagation. The simplified geometry for the heat exchanger investigated in this paper is a two-dimensional rectangular duct with two half cylinders with a bias flow going through the gap between the cylinders. In the current study, the acoustic response is predicted numerically with the cold flow only and compared to the experimental data, as a preparation for the next study with the hot flow.