In the second modeling (case 2), four samples from 18 experiment samples designed in [12] is modeled. Samples 1, 8, 10 and 18 from Ref. [12] are selected due to have the maximum and minimum efficiencies. Table 5 presents the complete geometries of these four samples. A mixture of 50% water and 50% ethylene glycol is considered for coolant which in samples 1 and 2 circulate clockwise while in samples 3 and 4 circulates counter clockwise. Type and number of generated meshes for these samples are presented through Table 6. Contours of Fig. 9 which are plotted for 20% load and 4500 rpm shows the effect of temperature distribution in the heat exchanger and zoomed areas clearly show the conduction heat transfer through the fins. Comparisons of outlet cold fluid temperature for all samples with experimental results are shown in Fig. 10 (left) and for sample 4 (right) in different engine loads. As revealed Lee and Bae [12], it seems that samples 1 and 3 (samples 1 and 10 in [12]) have the smallest effectiveness and samples 2 and 4 (8 and 18 in [12]) have the largest cooling effectiveness due to water outlet temperature. Because sample 4 has the maximum cooling performance, its temperature contours in different loads are shown in Fig. 11 in front and side view of the central plane. Finally by calculating the recovered heat amount, Fig. 12 is depicted for all four samples in different engine loads. As seen, maximum heat recovery is approximately 5900 W which occurs when engine speed is 4500 rpm and 100% load in sample 4 due to higher fin length, thickness and numbers.