The total heat transfer quantity deviation resulting from nonuniform fluid flow velocity distribution in each conduit of the heat exchanger has been studied by using theoritical analysis and numerical simulation methods. The results of numerical simulation calculation are in comformity with those of theoritical analysis. The heat transfer of both the axial flow inside the tubes and the transvrse flow outside the tubes for the said heat exchanger has been included in the study. The results of study show that the total heat transfer quantity deviation is within 3% during the time of nonuniformity concering fluid flow velocity in each conduit reaching four times under condition of constant wall temperature

but the pressure drop between inlet and outlet increases about 23%.