A flow calorimeter based on energy conservation was constructed for experimental measurements of isobaric specific heat capacity. The relative expanded uncertainty of isobaric specific heat capacity was identified as 2.32% (coverage factor k = 2). In the peak region, the relative expanded uncertainty of isobaric specific heat capacity increased to 7.10% (coverage factor k = 2). To verify the accuracy and reliability of the flow calorimeter, pure water and different mole-fraction binary mixtures of n-pentane and acetone were tested in the liquid and vapor phases. The maximum absolute deviation and average absolute deviation were 1.42% and 0.51%, respectively. The isobaric specific heat capacity of emulsified kerosene with different mass fractions was measured at temperatures ranging from 301 K to 878 K and at pressure p = 3 MPa. The effects of different mass frictions of water and temperature on the isobaric specific heat capacities were analyzed in detail. Finally, the isobaric specific heat capacity of RP-3 was compared with that of emulsified kerosene.