Research on heat exchange and control method of the evaporative condenser in the equipment of flax fiber modification

• The heat exchange process of ammonia recovery system was analyzed.
• A mathematical model was developed to evaluate the heat exchange.
• Thermal load of ammonia recovery system was computed, and its main influence factors were analyzed.
• Spraying water pump and fan were controlled to improve the efficiency of evaporative condenser.

Aiming at improving heat utilization of the evaporative condenser in the equipment of flax fiber modification, we proposed a new method to control the main factors that affect the heat exchange of the evaporative condenser. Firstly, a steady-state mathematical model was developed to evaluate the heat exchange of evaporative condenser after analyzing the heat exchange process of ammonia recovery system in the modification equipment and the thermal mass transfer process of evaporative condenser on details. Then, the thermal load of evaporative condenser was computed and analyzed through the numerical simulation. It is found that the suction pressure of compressor has obvious influence on the thermal load of evaporative condenser. Besides, under the maximum suction pressure, the thermal load is 291.4 kW, and the corresponding air speed and spraying water volumetric flow rate are 2.5 m/s and 12 m3/h, respectively. When the thermal load decreases, the air speed and spraying water volumetric flow rate are adjusted accordingly.