Exergy Analysis of Advanced Adsorption Cooling Cycles.

Ngoc Vi Cao,Xuan Quang Duong,Moon Yong Park,Jae Dong Chung,Woo Su Lee,Seung Soo Lee

doi:10.3390/e22101082

Abstract

This study conducted an exergy analysis of advanced adsorption cooling cycles. The possible exergy losses were divided into internal losses and external losses, and the exergy losses of each process in three advanced cycles: a mass recovery cycle, heat recovery cycle and combined heat and mass recovery cycle were calculated. A transient two-dimensional numerical model was used to solve the heat and mass transfer kinetics. The exergy destruction of each component and process in a finned tube type, silica gel/water working paired-adsorption chiller was estimated. The results showed that external loss was significantly reduced at the expense of internal loss. The mass recovery cycle reduced the total loss to 60.95 kJ/kg, which is −2.76% lower than the basic cycle. In the heat recovery cycle, exergy efficiency was significantly enhanced to 23.20%. The optimum value was 0.1248 at a heat recovery time of 60 s. The combined heat and mass recovery cycle resulted in an 11.30% enhancement in exergy efficiency, compared to the heat recovery cycle. The enhancement was much clearer when compared to the basic cycle, with 37.12%. The observed dependency on heat recovery time and heating temperature was similar to that observed for individual mass recovery and heat recovery cycles.

Highlights

Adsorption cooling systems (ACS) are considered a promising solution for the shortcomings of vapor compression refrigerators
Based on the information obtained from the energy analysis, an exergy analysis was performed using MATLAB code to estimate the exergy destruction in each process and component, and the exergy efficiency of the system was evaluated
The results of the exergy analysis for the typical working conditions in Table 1 are given in Figure and Table 2

Summary

Introduction

Adsorption cooling systems (ACS) are considered a promising solution for the shortcomings of vapor compression refrigerators. ACS can be driven by low-grade heat sources (60–90 ◦ C) such as solar energy, industrial waste heat, or exhaust heat from engines. They can utilize eco-friendly refrigerants like water, methanol or ethanol. The system suffers from a low coefficient of performance (COP) and low specific cooling power (SCP). A number of advanced operating cycles have been developed, including a heat recovery cycle [1,2,3], a mass recovery cycle [4,5,6,7], and a combined heat and mass recovery cycle [8,9,10]

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Conclusion