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ABSTRACT
Parabolic solar collectors have been used for feed water heating process instead of extractions from steam turbines to enhance the power output and heat rate for a coal-fired thermal power plant. In this analytical work, entropy-exergy concepts have been applied on steam turbines and solar collectors at 60, 80 and 100% plant loads, and found different performance parameters with percentage variations in that parameters. After analyses, it has been found that maximum flow rate achieved for intermediate-pressure steam turbine with maximum outputs but maximum rates of exergy destruction and entropy generation at 100% load. Maximum percentage increments in total and net powers but minimum decrement in heat rate attained at 100% load which prove that plant must be operated at full load without extraction from turbine. Comparative analyses have also been shown maximum heat gain rate, inlet and exergy gain rates from the solar collectors found at 100% but minimum found at 60% load.
List of symbols, abbreviations and Greek words
| A | = | Leakage through high-, intermediate- and low-pressure steam turbines kg/s |
| As | = | Aperture area of the solar collectors in m2 |
| Cp | = | Specific heat at constant pressure in kJ/kg-K, |
| FlFu | = | Flow function in m2 |
| h | = | Enthalpy of steam for high-, intermediate- and low-pressure steam turbines kJ/kg |
| HR | = | Heat gain rate for thermal power plant |
| IbRb | = | Solar intensity in W/m2 |
| Lmech | = | Mechanical loses in the power plant in kW |
| mst | = | Flow rate of steam flowing through the steam turbines in kg/s |
| mwt | = | Mass flow rate of water flowing through the solar collectors in kg/s |
| P | = | Actual power output in kW |
| Pnet | = | Net power output from the coal-fired thermal power plant with considering losses and efficiency in kW |
| PT | = | Total power output without considering losses and efficiency in kW |
| Pst | = | Pressure of steam in N/m2 |
| QB and QSH | = | Rates of heat addition in the boiler and super heater in kW |
| S | = | Entropy of steam in kJ/kg-K |
| Sgen | = | Entropy generation rates of high-, intermediate- and low-pressure steam turbines in kJ/s-K |
| T0 | = | Atmospheric temperature in kelvin |
| Tw | = | Temperature of the water flowing through the collectors in kelvin |
| Vst | = | Specific volume of steam in m3/kg |
List of abbreviations
| 0 | = | Ambient condition |
| B | = | Boiler |
| Gen | = | Generation |
| HPT | = | High-pressure turbine |
| In | = | Inlet condition |
| IPT | = | Intermediate-pressure turbine |
| LPT | = | Low-pressure turbine |
| Out | = | Outlet condition |
| SH | = | Superheater |
| St | = | Steam |
| Wt | = | Water |
List of Greek words
| ηgen | = | Generator efficiency in percentage |
| γ | = | Maximum useful work available from solar irradiation |
Acknowledgments
This analytical work is carried out at Sushila Devi Bansal College of Technology, Indore, India. The author is very thankful to BHEL Bhopal for providing useful information/data which is used in this case study. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit stores.
Disclosure statement
There is no conflict of interest between authors.
Additional information
Notes on contributors
Ankur Geete
Dr. Ankur Geete is working as Associate Professor in Mechanical Engineering Department at Sushila Devi Bansal College of Technology, Indore, India. He has published many research papers in various national and international journals. He has guided lot of research projects with under graduate and post graduate students/scholars. He is currently working on different heat exchangers, parabolic solar collectors and thermal power plants with scholars.
