This article presents a numerical study of particle deposition in two fluids, i.e., liquid and droplet flow in a single row tube bundle heat exchanger. The tubes in the heat exchanger are modeled as heating sources. Two level-set functions are used to capture the liquid-droplet interface and the liquid-deposit front. The effects of different parameters, including Damköhler number, thermal conductivity of the deposit, viscosity of the liquid, and the heating power of the tube on the flow and heat transfer, are investigated. The deposit profiles on the tube surface are analyzed. Comparison is made for the averaged Nusselt number for the case without and with deposition. It is found that the tube surface has a thicker deposit at the upstream facing side compared with that of the downstream facing side. Generally, the heat transfer rate reduces with the growth of the deposit. Under certain conditions, heat transfer can be increased because of the increase in fluid velocity due to blockage of the flow area by the deposit. The averaged Nusselt number oscillated temporally in response to the droplet movement across the tube. Generally, the temperature at the liquid-deposit front decreases with thicker deposit formed. The averaged Nusselt number along the liquid-deposit front increases to a critical value initially, and it starts to decrease with the growth of the deposit.