## 1 Introduction
A basic binary geothermal power plant operates a geothermal fluid (prime) to ensure thermal input of a pressurized fluid (organic fluid) into an Organic Rankine Cycle (ORC). Geothermal brine heats the organic working fluid (R134a, \(n\)-pentane, isopentane) in a preheater and evaporator which later vaporizes. This steam produces electrical energy by passing through a turbine driving the generator. The working fluid passing through the turbine is generally condensed in an air-cooled condenser before being pumped to the preheater [12]. After the oil crisis of the 1970s, it was understood that energy efficiency alone could not determine how properly energy was used. Thus exergy analyses began to gain great importance. However, the basis of exergy extends to the 1870s. It was first proposed by [PERSON] in 1878 [13]. The exergy concept as a word was first used by [PERSON] in the year 1953 [4]. Available energy [14], available work [13] and availability or maximum beneficial work [15] concepts were proposed with equivalent meaning to exergy. [PERSON] and [PERSON] [16] brought energy use, in addition to exergy use, to the agenda in Turkey in 1995. The results of their studies completed exergy analysis of apparently efficient systems, and revealed just how inefficient these systems actually were. The most appropriate design for geothermal power plants is a complicated work encompassing multiple scientific and engineering disciplines. As a result, information should be synthesized about a variety of topics to make appropriate decisions related to the approach to be used and research methods [17; 18; 19; 20; 21; 22]. Currently characterization of energy resources, power plant design and engineering optimization topics require creation of a conceptual framework comprising the knowledge of the latest available technology and current research. Consequently, energy inputs to the electricity power plant requiring knowledge related to available geothermal resources in the world, in general, should be accurately estimated. During the process of geothermal power plant design, design and modelling research should be fully understood, requiring detailed investigation of operating and continuing power plants. Also, conscious and correct decisions should be made relating to application of the most appropriate optimization techniques. This requires detailed investigation of the literature emphasizing techniques to bring energy power plants or thermal systems to the best state and optimization methods for engineering applications. The majority of scientific studies have focused on design optimization, selection of appropriate fluid, exergy/energy analyses and a variety of techno-economic research. Additionally, a common characteristic of ORC-based systems is the multiple nature of working conditions. The majority of application areas experience variations in thermal resource (or cooling processes) over time and the system should adapt to the working regime to ensure optimum performance. There are few studies related to control aspects and off-design performance of ORC systems [23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35]. Thus, all the following studies are related to low temperature ORCs. As the development of renewable energy resources has intensified, the researches into ORC technologies producing electricity from low enthalpy geothermal resources have increased. The majority of these studies revolve around geothermal binary power plants and their design. At the beginning of the 1970s, [PERSON] [36] explained the design of the first binary geothermal binary power plant in the USA, known as Magmamax (and second globally). A short while after, [PERSON] et al. [37] developed a computer model to research the effect on levelized cost of electricity (LCOE) with five different temperatures for a Rankine cycle power plant with simple propane-based geothermal resource. [PERSON] [38] studied the design of a Rankine cycle power plant with dual pressure using isopentane as working fluid.