Análise exergoeconômica de um sistema CCP composto por um ciclo rankine orgânico e um sistema de refrigeração por absorção

Abstract

The objective of this work is to carry out an exergoeconomic analysis in an Organic Rankine Cycle (ORC) with the introduction of an Absorption Refrigeration System (SRA) in the condenser cooling. In addition, this work also aims to improve the efficiency of the thermal energy source utilization and to present parametric analyzes of performance from the thermodynamic and economic points of view. To evaluate the relative efficiency increase, two configurations were analyzed: Simple Organic Rankine Cycle (ORC-S) and Combined Organic Rankine Cycle (ORC-C). The essential difference is that the ORC-S rejects heat to a cooling tower and has the power produced by the expander as its only product, while the ORC-C works in combination with an ARS and has the power produced by the expander, the heat removal from the ORC condenser and the heat removal from a room as products. The combination of the systems is done through a connection between the ORC condenser and an ice water storage tank that performs thermal exchanges with the ARS evaporator. The purpose of joining the two systems is to allow the reduction of the ORC condensation temperature and the search for the power and efficiency increase in the use of the energy provided by the thermal source. The ORC system under study uses a scroll type expander and operates with R-134a as working fluid. The ARS considered was a simple effect one using the water-lithium bromide pair. The thermodynamic modeling of the system was developed based on the specification of input parameters such as temperature at the expander inlet, pressure ratio and temperature of the supplied ice water. The thermodynamic analyzes were carried out through an energy and exergy study, of the two configurations, obtained by applying the principles of the first and second law of thermodynamics. The economic study was carried out through an exergoeconomic analysis, developed through the application of the SPECO (Specific Exergy Costing) method. The exergoeconomic equations were developed using input data specification such as the specific costs of energy from the heat source, the ice water and the electricity rate.