Grey relational analysis of an integrated cascade utilization system of geothermal water

Abstract

With the drastic decrease in fossil resources and rapid deterioration of the global environment, the utilization of geothermal resources has been strongly advocated. The combination of heat, power, and cold utility generation is commonly used to increase the utilization efficiency of geothermal resources. In this study, an integrated cascade utilization system of waste geothermal water (ICUWGW) from a flash geothermal power plant in China is established to increase the utilization efficiency of geothermal water. The waste geothermal water leaving the power plant is proposed for further use in cascade for twostage LiBr/H 2 O absorption cooling, agricultural product drying, and residential bathing. Twelve candidate temperature schemes showing different inlet and outlet temperatures of every subsystem are proposed for the ICUWGW. Several criteria are selected for the evaluation and screening of the candidate schemes. Grey relational analysis incorporating analytic hierarchy process is conducted to screen the optimal temperature scheme for the ICUWGW to meet the comprehensive criteria of thermodynamics and economics. Results show that the optimal scheme features significant improvement in energy efficiency, exergy efficiency, and equivalent electricity generation efficiency compared with those of the current geothermal power plant. The investment payback time of the additional subsystems for cooling, drying, and bathing is 1.85 years. Exergy analysis is also conducted to determine the further optimization potential of the optimal ICUWGW. Sensitivity analysis of electricity price on the performance of the optimal ICUWGW is also performed.

Recent advances in sustainable drying of agricultural produce: A review

“…The dryer was used to dry Nylon Sago, and COP of the combined system reportedly varied from 1.4 to 1.8 depending on the temperature of heat sink. Luo et al [69] investigated retrofitting of Dengwu geothermal power plant using heat recovery. The proposed configuration utilised recovered heat for space cooling and drying of longan fruits.…”

“…Increasing the velocity of drying air has little influence on exergy efficiency [128]. A recent comprehensive review of exergy analysis of drying systems was presented by Aghbashlo et al Luo et al [129] worked on a grey relational evaluation of an hybrid cascading technique where the waste water from an existing geothermal plant was proposed to be used for drying of logan fruits and bathing water provision. The new configuration increased system exergy efficiency from 12.76% to 25.81%.…”

The Evaluation for Educational Investments

“…The potential of schools for educational investments (final evaluation value) is calculated by using the method of Grey Correlation Analysis [2,3,4].…”

Multi-Response Optimization of Coagulation and Flocculation of Olive Mill Wastewater: Statistical Approach

“…In the engineering and technical literature, the most popular technique is Deng's grey relational analysis (GRA) model, permitting a multi-objective optimization and evaluation of process parameters. Some applications of the GRA model are as follows: (i) optimization of powder metallurgy processing parameters of the Al 2 O 3 /Cu composite using the GRA model coupled to the Taguchi method [13], in order to optimize electrical discharge machining process parameters; (ii) optimization of the process parameters for machining aluminum hybrid composites using electrical discharge machining (EDM) [14]; other researchers [15,16] also led works on EDM using the GRA model coupled with the Taguchi method for the multi-optimization of the micromachining process parameters; (iii) principal component analysis combined with multi-objective optimization of process parameters for hard turning of AISI 52100 steel was carried out [11]; (iv) Aslantas et al [17] applied micro-milling to TI-6Al-4V, whereas another researcher [18] used the analytic hierarchy process (AHP) integrated GRA model to analyze the integrated cascade utilization system of waste geothermal water; (v) the relationships between some parameters to study the degree of the relative importance of the influencing factors about fractal dimensions for super pulverized coal particles were studied [19]. The list is only a selection of case studies that involved the GRA model or variants to seek successful process optimization.…”