A novel heat recovery exchanger installed on the rotary kiln shell surface is proposed in this paper. The heat recovery exchanger contains water tubes and coiled pipes

which function as the radiative and the convective heat transfer surfaces

respectively. Numerical studies and experimental measurements are carried out to investigate the heat transfer characteristics of the heat exchanger. Several optimization models are proposed with the heat transfer area

the pressure drop and the modified entropy generation numbers set as the objective functions. The models describe the relation between the heat transfer rates and structural parameters of the heat recovery exchanger

i.e. the tube length

the tube numbers and the tube diameter. The optimized design parameters are obtained by applying the genetic algorithm toolbox in Matlab. The results indicate that the optimized heat transfer areas of water tubes and coiled pipes are decreased by 15% and 20%

respectively. The corresponding pressure drop is significantly decreased after optimization. In the optimization process

the modified entropy generation numbers are decreased due to fluid friction

while the modified entropy generation numbers remain unchanged due to heat transfer.