Magnetic field enhancement in water-lithium bromide absorption refrigeration systems

Absorption refrigeration systems are generally characterized by low Coefficient of Performance (COP). Absorption enhancement is an effective way of improving the COP of refrigeration systems. Literature is sparse on the use of magnetic field for the enhancement of absorption refrigeration systems despite its cheapness and environmental friendliness as compared with other enhancement methods. Although the method has recently been employed on ammonia solution, its influence on lithium bromide (LiBr) solution is yet to be fully studied. In this paper a numerical model for the magnetic field enhancement in water-LiBr absorption systems was developed and evaluated. The flow within the film thickness to the absorber wall was considered as a two-dimensional steady laminar flow. A Finite Difference model was developed based on conservation of mass, momentum, energy equations and mass transport relationship. The model was validated using data from the literature on ammonia solution. Standard parameters including absorber wall length (1 m), film thickness (10-3 m), magnetic field vacuum permeability (1.257 x 10-6 kgmA-2s2), magnetic mass susceptibilities and magnetic induction intensities were used for LiBr solution' modeling. Changes in their concentrations, both in the direction of falling film and across its thickness, were investigated. Data were analysed using descriptive statistics and Student's t-test (p=0.05). The concentration distribution of lithium bromide solution in the direction of falling film was between 54.9% and 60.0% for the magnetic induction range of 0.0 and 3.0 Tesla. Across the film thickness and for the same range of magnetic induction, the concentration distribution was between 0.0 and 0.19. The concentration of the solution increased from 0.0 to 21.7 when magnetic induction was increased from 0.0 to 3.0 Tesla, implying higher cooling effect. The COP of lithium bromide solution absorption refrigeration system was increased by 0.3% for magnetic induction of 3.0 Tesla. Magnetic field enhanced the absorption performance in the lithium bromide solution; hence can be used in typical absorption refrigeration systems.