Marine heat exchanger, heat exchange system and heat exchange control method

The invention discloses a marine heat exchanger, a heat exchange system and a heat exchange control method. The heat exchanger comprises a body internally provided with two independent heat exchange cavities, the body is provided with cooling liquid inlets/outlets communicated with the two heat exchange cavities in a one-to-one correspondence manner, and one cooling liquid inlet/outlet is provided with an electronic throttle valve; and cooling core pipes are arranged in the two heat exchange cavities, and the body is provided with an outer circulating water inlet/outlet and a first temperature sensor which are communicated with the cooling core pipes. The heat exchange system comprises the heat exchanger. The method comprises the following steps that 1, the opening degree MAP of the electronic throttle valve is searched according to the current rotating speed and torque, the corresponding opening degree of the electronic throttle valve is obtained, and when the external circulating water temperature is equal