Numerical analysis of falling film absorption with ammonia-water in magnetic field

Absorption strengthen is an effective way to improve the coefficient of performance (COP) of ammonia-water absorption refrigeration system. A mathematical absorption model for ammonia-water falling film absorption in magnetic field was built in this paper to study the influence of magnetic field on the absorption process. Macroscopic magnetic field force was introduced to the mathematical model. Changes in physical properties of ammonia-water solution while absorbing, the variation of falling film thickness along falling and the convection in the direction of thickness of liquid film have been considered in modeling. Numerical results showed that magnetic field have positive effect on the ammonia-water falling film absorption to some degree. When the magnetic induction intensity at the solution's inlet is 3 Tesla (T), the increment in concentration of ammonia-water solution at outlet is 1.3% and the absorbability increased by 5.9%. The COP of a simple ammonia-water absorption refrigeration system increased by 4.73% and the decrement in circulation ratio is 8.3%. (C) 2006 Elsevier Ltd. All rights reserved.