Heat exchanger

A heat exchanger for performing a heat exchange between an air flow and a coolant flow which flows in a coolant flow direction;

• comprising
• a plurality of tube elements;
• a plurality of fins, said fins being alternately stacked with said tube elements;
• a pair of tank elements which are disposed on opposite sides of said tube elements and which receive the coolant flow;
• each of said tube elements including a first coolant flow passage which is on a rear side of said air flow, and a second coolant flow passage which is on a front side of said air flow, said second coolant flow passage being located downstream of said first coolant flow passage with respect to said coolant flow direction;
• each of said first coolant flow passages being connected together through said tank elements so that all of said first coolant flow passages form one passage in parallel;
• and
• each of said second coolant flow passages being connected together through said tank elements and being divided into at least two groups each of which forms one passage in parallel with the other respectively, one of said groups of second coolant flow passages receiving coolant flow upstream of the other group of second coolant flow passages with respect to the coolant flow direction.