Saving energy and getting effective solutions for that is an issue that has become an important topic for engineers in recent years. In the present study, fluid flow and heat transfer have been studied experimentally and numerically in a channel with a square cross-section equipped with transverse tube bundles. The transverse tube bundles are hollow and perpendicular to the direction of flow. Water presents as the cooling fluid and the Reynolds number range is between 3767 to 12559. Temperature profiles are used for the boundary condition on the channel wall. Then effects of various parameters such as change in length, arrangement, diameter of the transverse tube bundles and fluid flow on the heat transfer rate is investigated. The governing equations of the problem simulation included the equation of continuity, the motion, and the energy. Fluent software with simple algorithm and k-? turbulent model has been used for numerical analysis. In all Reynolds numbers, the passage of the transverse tube bundles has resulted in an increase in heat transfer and a drop in pressure relative to the simple channel. According to the results, the use of transverse tube bundles with a length of 17.5 cm with a inline arrangement increases the heat transfer coefficient by 1.2 times compared to the simple channel. However, based on the performance evaluation criteria, it was determined that this arrangement will not perform well in all cases. The use of 17.5 cm long tubular tubes with a staggered arrangement increased the heat transfer coefficient by 1.7 times compared to the simple case and at the same time had a performance evaluation criterion greater than 1. If the beginning and end of the transverse tube bundle are open and steam is allowed to enter them, the use of 17.5 cm long transverse tube bundles with staggered arrangement in all dimensions will be justified based on performance evaluation criteria. Keywords: Heat transfer, Heat transfer channel, Transverse tube bundles, Hollow pipes, Performance evaluation criteria
