Abstract
In this paper, a new small-scale lithium bromide (LiBr)-water absorption system consisting water-cooled evaporator and air-cooled condenser is experimentally studied. For compactness, water-cooled heat exchangers for evaporator, absorber and generator are made helical-coiled type, whereas, based on the water availability and load requirements, condenser is air-cooled. Accurate empirical correlations for thermal load and evaporator temperature against system driving factors concerning a have been reported. Thereafter, response surface analysis of the developed performance parameters are studied with respect to LiBr concentration, temperature of generator and mass flow rate of hot water. Using experimental data, estimation of overall heat transfer coefficient (U) and its variation with system driving factors is quantified. The error margin between theoretical and actual pressure loss is limited within 5 %. Next, a multi-objective inverse analysis of the developed system is done to simultaneously retrieve the required LiBr concentration, mass flow rate of hot water, and vapor generator temperature to derive a desired cooling performance demand from the system. The obtained U values for all the components are found to be in line with the standard data. The physics related to salt concentration and generator temperature in governing U values are reported. Apart from the developed correlations, it can be established that the necessary operational parameters can be predicted by the present multi-objective inverse method to meet the necessary thermal load and temperature demands within an accuracy level of 6 % and 5 %, respectively.
Multi-objective optimization of CCHP system with hybrid chiller under new electric load following operation strategy
