The experimental system for measuring the convective heat transfer coefficient SNG-1153 shown schematically in Fig. 1. It consists of a [HMIM]BF4 IL loop, a water loop, a test section and a measuring and control unit. The test section is a counter flow concentric double-tube heat exchanger, in which the IL flowed inside the inner tube. The inner tube includes smooth and microfin tubes, the effective lengths are 600 mm. Configurations of the microfin tube are illustrated in Fig. 2 and dimensions of the test tube are shown in Table 1. The smooth tube and microfin tube are tested, respectively. The cooling water flows in the annular space between an inner tube and a concentrically placed outer shell (copper, outer diameter of 16 mm and wall thickness of 1 mm) supply in a water tank. The outer surface of the shell was thermally insulated to reduce heat loss. IL is supplied to the inner tube of the double-tube heat exchanger from an electrically heated oil bath (GX-2005, Yisheng Experimental Instrument Co. Ltd. Guangzhou) with the volume of 6 L. The outlet temperature of the IL from the oil bath is controlled by a solid state control, so carbohydrates the oil bath delivers a desired high temperature fluid to the heat exchanger.