Superstructure-Based Optimization of Vapor Compression-Absorption Cascade Refrigeration Systems.

Sergio F Mussati,Miguel C Mussati,Tatiana Morosuk

doi:10.3390/e22040428

Abstract

A system that combines a vapor compression refrigeration system (VCRS) with a vapor absorption refrigeration system (VARS) merges the advantages of both processes, resulting in a more cost-effective system. In such a cascade system, the electrical power for VCRS and the heat energy for VARS can be significantly reduced, resulting in a coefficient of performance (COP) value higher than the value of each system operating in standalone mode. A previously developed optimization model of a series flow double-effect H2O-LiBr VARS is extended to a superstructure-based optimization model to embed several possible configurations. This model is coupled to an R134a VCRS model. The problem consists in finding the optimal configuration of the cascade system and the sizes and operating conditions of all system components that minimize the total heat transfer area of the system, while satisfying given design specifications (evaporator temperature and refrigeration capacity of −17.0 °C and 50.0 kW, respectively), and using steam at 130 °C, by applying mathematical programming methods. The obtained configuration is different from those reported for combinations of double-effect H2O-LiBr VAR and VCR systems. The obtained optimal configuration is compared to the available data. The obtained total heat transfer area is around 7.3% smaller than that of the reference case.

Highlights

Refrigeration is one of the varieties of low-temperature thermal engineering applications in different industries such as large food and drink industries, refineries and chemical plants, mechanical engineering, electronic devices, and other types of industries
The optimization model was implemented in the platform GAMS v.23.6.5 [37] and solved with the solver CONOPT 3 v.3.14W [38]
Before solving the optimization problem stated in the previous section, the proposed model was succesfully verified using the data reported by Colorado and Rivera [31], which is here used as a reference case

Summary

Introduction

Refrigeration is one of the varieties of low-temperature thermal engineering applications in different industries such as large food and drink industries, refineries and chemical plants, mechanical engineering, electronic devices, and other types of industries. The refrigeration industry is playing an important and increasing role in the global economy [1]. An intense research and development effort is still required in this area [2,3]. Vapor compression refrigeration systems (VCRS) are the most widely used commercially, followed by the vapor absorption refrigeration systems (VARS). The high electrical power consumption for VCRSs is still the main drawback of these systems. Not much electrical power is required for VARSs since only a small amount of energy to power a pump is necessary; they are preferred

Methods

Results

Conclusion