Thermodynamic analysis of lithium bromide absorption chiller driven by geothermal energy
The use of geothermal energy as a heat source to drive vapor absorption chillers has been receiving more interest. Geothermal energy is sustainable, economically viable and environmentally friendly. Absorption chillers powered by geothermal energy are still in their development phase. In this work, a lithium bromide absorption chiller operated with a geothermal heat source will be thermodynamically analyzed. The focus will be on the solution heat exchanger performance, in particular, the effect of geothermal heat source fluid temperature as well as mass flow rate on the absorption chiller coefficient of performance (COP). The effectiveness of the solution heat exchanger will be also studied and evaluated. Preliminary results showed that as the pressure in geothermal water vapor separator increased from 0.23 to 0.45 MPa, the absorption chiller cooling load increased by 28% while the COP decreased by only less than 1.4% at the same condenser pressure.
Ranking Locations Based on Hydrogen Production from Geothermal in Iran Using the Fuzzy Moora Hybrid Approach and Expanded Entropy Weighting Method
The present study aimed at ranking and selecting the superior geothermal project for hydrogen production in 14 provinces of Iran using a multi-objective optimization fuzzy hybrid approach through analyzing the ratio (fuzzy Moora) and expanded entropy weighting method. In this research, the extended entropy weighing method and the Fuzzy-Moora approach were utilized to weigh the criteria and project the ranking, respectively. In this research, 13 criteria for ranking the geothermal projects in Iran have been selected for hydrogen production. At first, the technical-economic feasibility of the projects was carried out in Homer software, and then the ranking process was performed with the proposed hybrid approach. The results showed that among 14 studied provinces using geothermal energy, the provinces of Bushehr, Hormozgan, Isfahan, Mazandaran, East Azarbaijan, Fars, Qazvin, Zanjan, Ardebil, Khorasan Razavi, Kerman, Sistan and Baluchestan, South Khorasan and West Azarbaijan were ranked in that order in terms of hydrogen production.
Thermodynamic analysis of models used in hydrogen production by geothermal energy
Four models are developed for the use of geothermal energy for hydrogen production. These include using geothermal work output as the work input for an electrolysis process (Case 1); using part of geothermal heat to produce work for electrolysis process and part of geothermal heat in an electrolysis process to preheat the water (Case 2), using geothermal heat to preheat water in a high-temperature electrolysis process (Case 3), and using part of geothermal work for electrolysis and the remaining part for liquefaction (Case 4). These models are studied thermodynamically, and both reversible and actual (irreversible) operation of the models are considered. The effect of geothermal water temperature on the amount of hydrogen production per unit mass of geothermal water is investigated for all four models, and the results are compared. The results show that as the temperature of geothermal water increases the amount of hydrogen production increases. Also, 1.34 g of hydrogen may be produced by one kg of geothermal water at 200 °C in the reversible operation for Case 1. The corresponding values are 1.42, 1.91, and 1.22 in Case 2, Case 3, and Case 4, respectively. Greater amounts of hydrogen may be produced in Case 3 compared to other cases. Case 2 performs better than Case 1 because of the enhanced use of geothermal resource in the process. Case 4 allows both hydrogen production and liquefaction using the same geothermal resource, and provides a good solution for the remote geothermal resources. A comparison of hydrogen production values in the reversible and irreversible conditions reveal that the second-law efficiencies of the models are 28.5%, 29.9%, 37.2%, and 16.1% in Case 1, Case 2, Case 3, and Case 4, respectively.