Academia.eduAcademia.edu

Figure 3 – uploaded by Davide Bonalumi

See full PDFdownloadDownload figure
Fig. 3. Optimized thermodynamic cycle with TiCl, in the Temperature-entropy plane in case of turbine inlet temperature of 500°C. Dashed lines refers to temperature profiles within the recuperator. increasing the temperature, the cycle efficiency increases and that the maximum of each curve is at higher evaporation pressure. The values of pressure that maximize the efficiency of the cycle are comprised in the range 25-45 bar for the investigated tempera- tures. These pressure and temperature are common for small- scale steam power plants. It is worth noting that the resulting opti- mized pressure interval refers to the range of subcritical cycles. Fig. 3 shows the power cycle in the Temperature-entropy diagram in the aforementioned optimized conditions, while Table 3 reports the values of the relevant thermodynamic variables in each point of the cycle. From the figure is possible to see that the expansion occurs in the dry region since both the inlet and the outlet of the turbine involve superheated vapor. From the point of view of the possible heat sources that can be effectively exploited by this power cycle, it can be seen from Fig. 4 that the heat introduced in the cycle provides an almost linear increase of the temperature of the working fluid, from point 2 to point 4 (with exception of the temperature plateau occurring during evaporation). Thus, heat sources suitable to match the variable temperature profile of the

Figure 3 Optimized thermodynamic cycle with TiCl, in the Temperature-entropy plane in case of turbine inlet temperature of 500°C. Dashed lines refers to temperature profiles within the recuperator. increasing the temperature, the cycle efficiency increases and that the maximum of each curve is at higher evaporation pressure. The values of pressure that maximize the efficiency of the cycle are comprised in the range 25-45 bar for the investigated tempera- tures. These pressure and temperature are common for small- scale steam power plants. It is worth noting that the resulting opti- mized pressure interval refers to the range of subcritical cycles. Fig. 3 shows the power cycle in the Temperature-entropy diagram in the aforementioned optimized conditions, while Table 3 reports the values of the relevant thermodynamic variables in each point of the cycle. From the figure is possible to see that the expansion occurs in the dry region since both the inlet and the outlet of the turbine involve superheated vapor. From the point of view of the possible heat sources that can be effectively exploited by this power cycle, it can be seen from Fig. 4 that the heat introduced in the cycle provides an almost linear increase of the temperature of the working fluid, from point 2 to point 4 (with exception of the temperature plateau occurring during evaporation). Thus, heat sources suitable to match the variable temperature profile of the

Related Figures (15)

Thermodynamic properties of TiCl4. * Calculated according to Eq. (1). Table 1 Some of the physical properties of TiCl, relevant to its applica- tion as working fluid in Rankine Cycle are listed in Table 1.
Thermodynamic properties of TiCl4. * Calculated according to Eq. (1). Table 1 Some of the physical properties of TiCl, relevant to its applica- tion as working fluid in Rankine Cycle are listed in Table 1.
Fig. 1. Plant layout assumed for the thermodynamic analysis. The plant scheme and the calculation assumptions are summarized in Fig. 1 and Table 2 respectively. Clearly, the plant configuration is that of a recuperative cycle, with the recuperator positioned between the pump and the boiler aiming at recovering part o the energy available from the turbine exhaust stream. As discussed in Section 2, this component becomes necessary, given the thermo- dynamic properties of TiCly, in order to enhance the plant conver- sion efficiency. The range of the variables and the value of fixed parameters are common for the investigated plant. Calculations are carried with software Aspen Plus V7.3 adopting the Peng- Robinson equation of state. The parameters of the TiCl, are avail- able within Aspen Plus. The thermodynamic model is validated with respect to the experimental data of the vapor pressure avail- able in the literature as it will be discusses in Section 4 (see Fig. 7a). Fig. 2 reports the cycle efficiency curve plotted as function of the evaporating pressure, for three different turbine inlet tempera- tures, in the range 400-500 °C. The highest efficiency of 36.2% is obtained in case of maximum temperature of 500 °C at the pres- sure of 40 bar. From the trend of the curves it is notable that,
Fig. 1. Plant layout assumed for the thermodynamic analysis. The plant scheme and the calculation assumptions are summarized in Fig. 1 and Table 2 respectively. Clearly, the plant configuration is that of a recuperative cycle, with the recuperator positioned between the pump and the boiler aiming at recovering part o the energy available from the turbine exhaust stream. As discussed in Section 2, this component becomes necessary, given the thermo- dynamic properties of TiCly, in order to enhance the plant conver- sion efficiency. The range of the variables and the value of fixed parameters are common for the investigated plant. Calculations are carried with software Aspen Plus V7.3 adopting the Peng- Robinson equation of state. The parameters of the TiCl, are avail- able within Aspen Plus. The thermodynamic model is validated with respect to the experimental data of the vapor pressure avail- able in the literature as it will be discusses in Section 4 (see Fig. 7a). Fig. 2 reports the cycle efficiency curve plotted as function of the evaporating pressure, for three different turbine inlet tempera- tures, in the range 400-500 °C. The highest efficiency of 36.2% is obtained in case of maximum temperature of 500 °C at the pres- sure of 40 bar. From the trend of the curves it is notable that,
Fig. 2. No-bleeding cycle efficiency as function of the evaporation pressure of TiCL. for three values of turbine inlet temperatures. Calculation assumptions as by Table 2. No pressure losses in the heat exchangers.
Fig. 2. No-bleeding cycle efficiency as function of the evaporation pressure of TiCL. for three values of turbine inlet temperatures. Calculation assumptions as by Table 2. No pressure losses in the heat exchangers.
Calculation assumptions. Table 2 Table 3
Calculation assumptions. Table 2 Table 3
Fig. 4. Electrical efficiency as function of the condensing temperature for CHP units based on the three plant solutions considered in Table 4. Thermodynamic properties in each point of the optimized thermodynamic cycle wit! TiCl, shown in Fig. 3.
Fig. 4. Electrical efficiency as function of the condensing temperature for CHP units based on the three plant solutions considered in Table 4. Thermodynamic properties in each point of the optimized thermodynamic cycle wit! TiCl, shown in Fig. 3.
Thermodynamic comparison between cycles with TiCl, and steam as working fluid. Calculation assumptions as by Table 2
Thermodynamic comparison between cycles with TiCl, and steam as working fluid. Calculation assumptions as by Table 2
Fig. 6b. Vapor pressure curve assumed as reference. Fig. 6a. Comparison among the measured vapor pressure curve with values obtained from literature and calculated with Aspen Plus using Peng-Robinson equation of state.
Fig. 6b. Vapor pressure curve assumed as reference. Fig. 6a. Comparison among the measured vapor pressure curve with values obtained from literature and calculated with Aspen Plus using Peng-Robinson equation of state.
Fig. 5. Test circuit utilized for the thermal stability analysis [12].
Fig. 5. Test circuit utilized for the thermal stability analysis [12].
Fig. 7. Saturation pressure curves after the stress tests at 400, 500 and 550°C compared with the reference values. MSE is the Mean Squared Error defined as MSE = to 4 (Pexpi — Prep i) where Px, is the measured pressure, Pref reference pressure and N the number of points.
Fig. 7. Saturation pressure curves after the stress tests at 400, 500 and 550°C compared with the reference values. MSE is the Mean Squared Error defined as MSE = to 4 (Pexpi — Prep i) where Px, is the measured pressure, Pref reference pressure and N the number of points.
Fig. 8. Values of temperature and pressure recorded during the thermal stress test carried out at 400 °C: absolute values (a) and percentage variation from the initial valt (b).
Fig. 8. Values of temperature and pressure recorded during the thermal stress test carried out at 400 °C: absolute values (a) and percentage variation from the initial valt (b).
Fig. 9. Values of temperature and pressure recorded during the thermal stress test carried out at 500 °C: absolute values (a) and percentage variation from the initial valu (b).
Fig. 9. Values of temperature and pressure recorded during the thermal stress test carried out at 500 °C: absolute values (a) and percentage variation from the initial valu (b).
Fig. 10. Values of temperature and pressure recorded during the thermal stress test carried out at 550 °C: absolute values (a) and percentage variation from the initial value b).
Fig. 10. Values of temperature and pressure recorded during the thermal stress test carried out at 550 °C: absolute values (a) and percentage variation from the initial value b).
Fig. 11. Values of temperature and pressure recorded during the thermal stress test carried out at 500 °C with samples of P91 and Cupronickel inserted in the test circui absolute values (a) and percentage variation from the initial values (b).
Fig. 11. Values of temperature and pressure recorded during the thermal stress test carried out at 500 °C with samples of P91 and Cupronickel inserted in the test circui absolute values (a) and percentage variation from the initial values (b).
Fig. 12. Summary of the vapor pressure curves obtained after each stress test carried oyf in the experimental analysis. MSE is the Mean Squared Error defined as MSE = + D (Pexpi — Prep i)” where Pexp is the measured pressure, Pye reference pressure'ahd N the number of points.
Fig. 12. Summary of the vapor pressure curves obtained after each stress test carried oyf in the experimental analysis. MSE is the Mean Squared Error defined as MSE = + D (Pexpi — Prep i)” where Pexp is the measured pressure, Pye reference pressure'ahd N the number of points.
Related topics:
Mechanical EngineeringInterdisciplinary EngineeringApplied Thermal Engineering
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved