# Condenser Design for On-Board ORC Recovery System
## 2 Cycle Analysis  
Firstly, the study of the selected working fluid, R245 fa (Pentafluoropropane), is necessary for the project (see Figure 1). R245 fa: HFC-245 fa is also known as pentafluoropropane and its chemical name is 1,1,1,3,3-Pentafluoropropane. It has no ozone depletion potential and is nearly non-toxic [16; 17]. The p-h diagram is shown below. From the literature, it has been estimated that the temperature of the exhaust gas is 720 K (450 \({}^{\circ}\)C). This fluid was selected because it is easily available and all its physical and chemical characteristics, as well as its environmental impact, are well known. Other fluids have been studied on paper and some tested in the laboratory, such as R134 [18]. The choice was made on the basis of the available data and on the basis of very precise experimental  
Figure 1: R245 fa p-h diagram. methodology and issues (availability, safety, etc.). Once the working fluid was defined, the following step was to create, with a customer plant cycle simulator, the basic ORC plant, with the following mandatory components: pump, turbine, heat exchanger, and condenser. The process sequence (Figure 2) is numbered and described as follows:  
1. 1-2: Expansion in the expander. The heat energy of the working fluid is converted into mechanical energy by an expander; then, an alternator (not represented) converts this mechanical energy into electricity. 2. 2-3: Condensation in a condenser. The vapour fluid condenses to the liquid state. 3. 3-4: Compression in a pump. A feed pump pressurizes the liquid working fluid. 4. 4-1: Vapourization in a boiler. The liquid working fluid absorbs thermal energy and vaporizes to the vapor state. Flows number 1-4 describe the thermodynamic cycle, 5-6 are the exhaust gas inlet and outlet, 7-8 are the cooling water inlet and outlet, and 9-10 are the power input/output for the pump and the turbine, respectively. The simulation input values are listed below. The power is the input data and the others are the experimental values of the operating 1800 cc diesel engine (the engine data are supplied by a previous laboratory test in the University department and reported in several previously published papers). 1. Power output: 5 kW. 2. The exhaust gas inlet temperature (T = 723 K). 3. The exhaust mass flow rate (\(\dot{m}\) = 0.3 kg/s). 4. The cooling water inlet temperature (T = 313 K). The thermodynamic simulation is needed to identify the operational conditions of the components and to analyze--in this particular case--the operative parameters of the condenser. Thus, Table 1 reports the results of the simulation. Figure 2: ORC plant on the simulator. The Process Simulator CAMEL-Pro(tm) is written in C++ and C#, is based on a completely--and authentic--object-oriented approach and is equipped with a user-friendly graphical interface that allows the simulation and analysis of several energy conversion processes. The system is represented as a network of components connected by material and energy streams; each component is characterized by a set of equations describing the thermodynamic changes imposed on the streams; in mathematical terms, this equation system is not closed, and, therefore, needs a proper number of boundary conditions in terms of known flow parameters. In practical terms, this means that the computed solution depends on both the plant configuration and on the assigned boundary conditions. An optimized Newton-Raphson iterative algorithm is used to solve the global equation system. The main feature of CAMEL-Pro(tm) is its modularity, which enables users to expand the code by adding new components or by modifying the model of the existing ones. In the gas model adopted in CAMEL-Pro(tm), the specific heat is calculated by a fifth-order polynomial in temperature, and enthalpy and entropy are obtained by the exact integration of these polynomials. The gas constant R is calculated according to the mixture rule.