In this paper, a theoretical and experimental investigation on HDH evaporation system performance was performed. A fixed size HDH system was constructed, and for the purpose to obtain the optimal operating parameters, a mathematical model was proposed to investigate the effect of the operating parameters on the evaporation rate and specific steam consumption (SSC). The evaporation rate is proportional to three operating parameters. SSC decrease with the increase of heat recovery ratio (HRR) in regenerator. Moreover, the operating parameters of the system were optimized to obtain minimum SSC using the GlobalSearch algorithm. The minimum SSC is 0.338-0398 kg per kg of evaporated water at different evaporation capacities. And the value of minimum SSC increases with an increase in the evaporation limit. Furthermore, the experimental results were compared with the optimized results, and they are in good agreement. Considering both the evaporation rate and SSC, the recommended operating parameters are: m(g)= 502.53 kg/h, m(t) = 3556.93 kg/h, T-lie = 83.59 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.