Extended exergy analysis of a novel integrated absorptional cooling system design without utilization of generator for economical and robust provision of higher cooling demands

Abstract

The focus of this study is on designing a novel system for the provision of high-capacity cooling and heating loads (4000 kW) with the utilization of absorption technology to increase economic viability and COP value of existing cooling plants via lower-grade waste heat sources (70 °C-90 °C). To achieve this aim, in the novel system, an integration including the LiBr-water solution based absorptional heat transformer (AHT), and absorptional cooling cycle (ACC), and flat plate solar collector (FPSC) systems was proposed. In the integration, the utilization of the generator in the cooling cycle was avoided with the interaction of the high-temperature LiBr-water solution (120 °C-150 °C) from the AHT system and ACC system evaporator. In this way, both the additional cost of the boiler and heat source and the enhancement of economic viability and COP value were achieved. Energy, economic, traditional, and extended exergy, sustainability, and environmental analyses were implemented in this novel system. The COP value for the cooling system was determined to be 3.10 from energy analysis. This result forms a significant indicator for achieving of the main focus of the current study with the proposed novel system. The annual heating and cooling duty generations with this novel system were computed as 52.37 GWh and 52.40 GWh, respectively. In the context of economically comparing the proposed system to other plants with similar scale that already exist, the initial overall expenditure, yearly operational expenses, and the time it takes to recover the investment for the proposed system were set at $4.56 million, $3.12 million, and 1.75 years, respectively. It is worth noting, though, that these figures fall within the range of $6–8 million, $5–7 million, and 5–10 years, respectively, for the currently operational plants. This result indicated that the proposed system provides a robust alternative to the existing cooling-heating cogeneration systems in terms of main output generation and is more economically viable. Also, the novel system gained annually US$3.89 million in energy costs. The conventional exergy analysis results were summarized by forming an exergy flow and loss diagram, namely, the Grassmann diagram. In addition, in this current study, the novel extended exergy flow diagram indicating extended exergy content components, energy carriers of the proposed system, and exergy product rate streams was also proposed and drawn for the proposed system.