Multiobjective optimization of a tri-generation ORC for power, freshwater and heat: suitable mixture of three fluid

Improving the performance of a trigeneration organic Rankine cycle for production of power, fresh water and heat using solar energy to respond the needs in remote areas is very important. One of the effective factors in the performance of such a cycle is the thermodynamic behavior of its working fluid which is classified into three categories: wet, dry and isentropic. Finding a suitable working fluid that has a good behavior in the power generation, fresh water production and heat is of particular importance. This study aims to find appropriate working fluid by analyzing, simulating and optimizing a trigeneration Rankine cycle powering with solar parabolic trough collectors for simultaneous production of power, fresh water and heat. The performance of this cycle is investigated with various mixture of organic fluids R152a, R600a and R1234yf (low ozone depleting potential (ODP) and global warming potential (GWP)) which are categorized in wet, dry and isotropic fluid, respectively. Therefore, first a parametric study is conducted and then followed by a multi-objective optimization (NSGA-II) for which power, fresh water and heat are the objective functions. While various mixture of these three working fluids are considered. The results show that three-component mixture is more suitable for achieving three goals simultaneously, while if one of the objectives is considered, only one of these fluids can be used according to the desired objective.