## 1 Introduction
This study demonstrated that for multiple turbine stages, the use of partial superheating with Single or Double Reheat stream showed a better performance in terms of efficiency. It also showed an increase in exergy destruction when heat source temperature was increased. A combined thermal power and cooling cycle which combines the Rankine and absorption refrigeration cycles has been presented by [12; 13]. Ammonia-water mixture was used as a working fluid. This cycle is ideally designed for solar thermal power using low-concentrating solar collectors. This cycle can also be used as a bottoming cycle for any thermal power plant. [PERSON] [14] presented an exergetic analysis of a combined power and cooling cycle that uses ammonia-water mixture as the working fluid [15]. He reported that such cycles use solar or geothermal energy or waste heat energy from a conventional power cycle. He also pointed out that an ammonia-water power cycle can be used as an independent cycle to provide the power output and cooling. [PERSON] reported that the boiling process and a heat transfer process at low temperature destruct the energy given to the boiler so that the energy efficiency is low; however, the exergy efficiency was higher than the energy efficiency. It was also reported by [PERSON], increasing the turbine inlet pressure decreases the energy and exergy efficiencies. Currently, interest is increasing in hybrid photovoltaic/thermal systems, which are a continuation of the photovoltaic solar system [16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28]. The PV solar panels and the thermal systems are integrated into one system known as photovoltaic (PV/T). The conversion efficiency of solar radiation to electricity in the solar cell ranges from 6% to 15% [24]. The rest of the fallen radiation is reflected, and the other part dissipated and absorbed as heat. Since PV cells must be placed under direct sunlight to produce electricity, their high temperature is inevitable [24]. Therefore, the PV/T systems of today are being extensively studied; in these systems, a heat exchanger is added to the PV cell to extract the excess heat, increase the electrical efficiency of the cell and utilize the heat absorbed by the PV cellsin other applications [24; 25; 26]. The heat exchanger used here is either an aluminum rectangular pipe or a tank set mounted on the back of the PV panels and through which the refrigerant fluids flow. [PERSON] et al. [24; 25; 26] developed and presented several numerical models to predict the performance of PV-Th under different conditions such as solar radiations from 500 to 1200 W/m2, heat transfer fluid flow in the back-heat exchanger, different nanofluids as heat transfer fluids and various cell temperatures [24; 25; 26]. Many researchers have conducted numerical and experimental studies to improve thermal conductivity using nanofluids and in various mixing methods. Reference [28] declared that thermal conductivity increased with temperature when suspended with nanostructure Al\({}_{2}\)O\({}_{3}\), CuO and water was used. The results of the study showed that the cooling fluid, which contains smaller particulate nanoparticles (CuO), show a thermal conductivity greater than the larger particles. Reference [28] developed two experimental equations to evaluate the effective thermal conductivity o nanomaterials and dynamic viscosity. In this study, the improvement in heat transfer by the dispersion of solid nanoparticles in the base fluid was calculated with different weights and temperatures ranging from 21 \({}^{\circ}\)C to 51 \({}^{\circ}\)C. The researchers used nanoparticles Cu, Al\({}_{2}\)O\({}_{3}\) and TiO\({}_{2}\) with cooling fluid (water and ethylene glycol). [PERSON] et al. [27] initiated a numerical simulation of heat transfer in a wavy channel and the improvement obtained using nanofluids made of nano-copper and water. The results showed that the use of nano cooling fluid with wavy walls enhanced the heat exchange between the wall and the flow significantly.