Theoretical analysis of the enhancement effect of ultrasonic oscillation on NH3-H2O falling film absorption process

Absorption refrigeration can utilize low grade heat, but the application is limited by the huge system size and low energy efficiency. The mass transfer area of absorber occupies more than 50% of the whole system. The improvement absorption effect of the absorber is significant to reduce the system size and improve the energy efficiency ratio. A method to enhance the mass transfer in an ammonia-water falling absorber by implementing ultrasonic oscillators is proposed in this paper. A mathematical model of the absorber with the installing of oscillator is established. The solution of the model shows that the total mass transfer coefficient and the ammonia absorbed rate are increased by 22.53% and 20.25%, respectively, when the sound intensity at the surface of oscillator is 20 W/m(2). The enhancement effect increases with oscillation output power, the ammonia absorbed rate increases by 31.2% when the sound intensity at the surface of oscillator is 50 W/m(2).

Automated summary

This paper proposes a method to enhance mass transfer in an ammonia-water falling absorber by implementing ultrasonic oscillators. The results show that the total mass transfer coefficient and ammonia absorbed rate increase significantly with the increase of sound intensity at the surface of the oscillator. The enhancement effect also increases with oscillation output power.