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

Abstract

The present work is composed by a comparative thermoeconomic analysis
between two refrigeration systems: Vapor Compression Cascade
Refrigeration System (VCCRS) and Integrated Refrigeration System by
Absorption and Vapor Compression (VCACRS). The thermoeconomic
analysis compares the systems under energy, exergy, economic and
environmental aspects. The development of mathematical models for each of
the 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 the
weighted sum of the objectives, this can be achieved by assigning different
weights for each goal, then a new function that represents the linear
relationship between all the objectives is found. In present case the two
objective functions are exergy destruction and total cost rate. In
multiobjective optimization, the process of choosing among optimized
solutions involves the definition of an equilibrium point, also called the
ideal point. In order to achieve a real solution of the minimum values of
the described functions simultaneously one must determine which is the
smallest distance from the ideal point to the curve that defines the
optimized solutions. In the study the economical advantage of VCCRS in
relation to VCACRS was demonstrated. VCACRS has a cost 10.26% lower
than VCCRS while VCCRS has a better exergetic efficiency, with its
destruction of exergy 38.46% lower than VCACRS.