Coal transport by sea transportation method including inter-islands barge system remains important means of bulk material transportation method. Depend upon the distance between the coal mine sites to the power plant sited, the coal transportation could take days or weeks. Prolonged transportation time could lead to self-heating leading to spontaneous combustion of lower rank coal. To prevent this, a heat exchanger submersion method is proposed to reduce the potentials of self-heating problem by means increasing the heat loss from the coal piles. This experiment work was conducted to determine the effect of cooling water flow rate on decreasing temperature of coal. Laboratory-scale experiments were performed using a stainless steel cylinder that opens at the top and insulated by rockwool to reduce heat loss. The heat source comes from the bottom which is heated by a hot plate heater. A U-shaped heat exchanger of laboratory-scale experiments was prepared. In this experiment, subbituminous coal was used. The effect of flow rate on the prevention of spontaneous combustion was studied by providing variations of the flow rates, thus the amount of heat taken from the heated coal bed. In this experiment the greater flow rate is accompanied by a higher decrease in coal temperature. Therefore, this heat exchanger effective for taking heat from the coal bed.