Thermoeconomic Simulation of Cascaded and Integrated Vapor Compression-Absorption Refrigeration Systems

Abstract

The present work is composed by a comparative thermoeconomic analysisbetween two refrigeration systems: Vapor Compression CascadeRefrigeration System (VCCRS) and Integrated Refrigeration System byAbsorption and Vapor Compression (VCACRS). The thermoeconomicanalysis compares the systems under energy, exergy, economic andenvironmental aspects. The development of mathematical models for each ofthe systems is performed through the EES (Engineering Equation Solver)program. The optimized functions are exergy destruction and total cost rate(sum of cost rates of investment, operation, maintenance and enviromental)by minimizing these functions. The optimization method used is theweighted sum of the objectives, this can be achieved by assigning differentweights for each goal, then a new function that represents the linearrelationship between all the objectives is found. In present case the twoobjective functions are exergy destruction and total cost rate. Inmultiobjective optimization, the process of choosing among optimizedsolutions involves the definition of an equilibrium point, also called theideal point. In order to achieve a real solution of the minimum values ofthe described functions simultaneously one must determine which is thesmallest distance from the ideal point to the curve that defines theoptimized solutions. In the study the economical advantage of VCCRS inrelation to VCACRS was demonstrated. VCACRS has a cost 10.26% lowerthan VCCRS while VCCRS has a better exergetic efficiency, with itsdestruction of exergy 38.46% lower than VCACRS.