The present disclosure relates to heat exchangers and heat exchange systems such heat exchangers. The heat exchangers include a shell having an inlet and an outlet and heat exchange tube bundles arranged therein. The shell includes a first region communicating with the inlet configured to accommodate the heat exchange tube bundles and a refrigerant input from the inlet. The refrigerant performs heat exchange with a fluid in the heat exchange tube bundles. A second region is arranged between the first region and the outlet and communicates with the first region and the outlet. A heating device is disposed in the second region. Embodiments may optimize spatial layout of the heat exchanger tube bundles, effectively improving the utilization of shell space of the heat exchanger the heat transfer efficiency of the heat exchanger at the same material cost, and enhance the overall performance, safety and reliability of the system.