01 12 06 2023 TEM Problems solution

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Department of Energy Politecnico di Milano Author Pag.1 of 11 Date 26/06/2023 Exam – Thermoeconomics and Energy Modelling 12-06-2023 Total score: 17 points (exercise 1 counts 2/3 of the total) Exercise 1. A research institution is developing a new heat transfer fluid named X -185 with advanced properties. The fluid is used in the Heat Exchanger (HE) of the plant presented in the figure. The institute wants to assess the maximum cost of the fluid (on exergy basis) given the target cost for electricity production by the turbine (T) equal to 0.25 €/kWh. Heat Exchanger takes in stream 1 that consists of CO 2. The purpose of Heat Exchanger is to increase the temperature of stream 1 in order to perform the following expansion. The heat is provided by the new heat transfer fluid, X-185 (stream 4 and 5). Considering that: - The cost of compressed CO 2 (stream 1) is 0.005 €/kWh on exergy basis. - Stream 5 of X-185 is collected and stored again. - The expanded CO2 stream is then discharged into the environment with zero additional cost. - Environment conditions are 25°C and 1 atm. You are requested to a. For each component write the exergy balance, compute exergy destructions, rational efficiency and functional efficiency. Highlight the information that are then relevant for completing the auxiliary equations. HE Ex2Ex1 Ex3 Ex5 Ex4 Wel T Table 1 Stream # 1 23.06 2 57.03 3 2.56 4 50.33 5 2.14 Wel 27.24 Table 2 model - T_baseline 0.85 3 HE 3 t_eX250i 0.90 5 t_eHW-75 0.75 2 Department of Energy Politecnico di Milano Author Pag.2 of 11 Date 26/06/2023 b. Considering the highest level of disaggregation of the plant, set proper auxiliary equations. Write the Thermoeconomics system of equations (check the coherence with the functional efficiencies) and derive analytically the cost…