The invention relates to a no-heat-exchange energy saving preparation device and method for preparing 
ammonia water from 
liquid ammonia directly. The preparation device comprises a cylindrical reaction tank, a water inlet is arranged at the bottom of the reaction tank, a diluted 
ammonia water outlet is arranged at the top of the reaction tank, a plurality of 
liquid ammonia inlets are arranged in the upper and middle part of the reaction tank, each 
liquid ammonia inlet is connected with a respective coil 
pipe. The coil pipes are installed in a staggered manner, and extend towards the middle and lower part of the reaction tank. Each coil 
pipe is connected with a respective 
distributor. The coil pipes are heated by 
heat energy generated by diluted 
ammonia water during the 
dilution reaction process, thus liquid ammonia in the coil 
pipe expands and absorb heat, thus heat generated during the liquid ammonia 
dilution reaction is reduced, liquid ammonia expands before 
dilution, and the liquid ammonia dilution speed is raised. The device takes full 
advantage of 
waste heat generated during liquid ammonia dilution, the liquid ammonia dilution efficiency is raised, the situation that energy is employed to lower the temperature of the diluted ammonia water is avoided, 
energy consumption is lowered and a lot of energy is saved.