Abstract
The steam produced can be utilized in a number of ways. In this study, steam is injected through a series of de Laval nozzles directed into the main turbine, to produce extra power in a compact arrangement. To minimize the size of the system, additive manufacturing was used for the heat exchangers, giving high performance per unit volume. The study demonstrates the feasibility of the cycle in producing power from waste heat using humid gas that already is present in most applications.
The experimental results show that the system is able to generate power at very low exhaust temperatures where the standard IBC would undoubtedly cease to operate. With an IBC inlet temperature of 370 °C, approximately 5 kJ/kg of specific shaft work was produced with 5 g/s of steam flow rate. At higher exhaust temperatures, the IBC and the Rankine cycle started to work together to increase the shaft power resulting in much higher specific work. At 620 °C, a specific shaft work of 41 kJ/kg was generated at a steam flow of 9 g/s. For the present turbomachinery sizes, this corresponded to 1933 W of power at 47 g/s of main exhaust flow.
A model of the thermodynamic system was created in order to study the sensitivity of the system to parameters such as the steam expander pressure ratio and efficiency. Higher steam pressure and higher steam expander efficiency both led to greater power generated for the same operating point, particularly at high IBC turbine inlet temperatures. The peak specific work for the range of parameters explored in the paper was 68 kJ/kg with a steam expander efficiency of 70% and exhaust conditions of 600 °C and 50 g/s. The plots produced in this study can be used as a guide for others considering this system to understand the expected power generated under a range of conditions.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition |
| Publication status | Accepted/In press - 8 Feb 2019 |
| Event | ASME Turbo Expo 2019 - Arizona, Phoenix, USA United States Duration: 17 Jun 2019 → 21 Jun 2019 https://event.asme.org/Events/media/library/resources/turbo/Turbo-Expo-2019-Program.pdf |
Conference
| Conference | ASME Turbo Expo 2019 |
|---|---|
| Country | USA United States |
| City | Phoenix |
| Period | 17/06/19 → 21/06/19 |
| Internet address |
Cite this
Investigation of a Combined Inverted Brayton and Rankine Cycle. / Kennedy, Ian; Duda, Tomasz; Liu, Zheng; Ceen, Bob; Jones, Andy; Copeland, Colin.
Proceedings of ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. 2019. GT2019-90767.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Investigation of a Combined Inverted Brayton and Rankine Cycle
AU - Kennedy, Ian
AU - Duda, Tomasz
AU - Liu, Zheng
AU - Ceen, Bob
AU - Jones, Andy
AU - Copeland, Colin
PY - 2019/2/8
Y1 - 2019/2/8
N2 - Waste heat recovery is an important technology in a world with increasingly stringent emissions legislation. One such means of recovering thermal energy is the inverted Brayton cycle (IBC). This paper presents, for the first time, an experimental study of a novel combination of the IBC with a Rankine cycle. The IBC requires cooling of the exhaust gases after expansion. If the gases contain water vapour, as is the case for hydrocarbon combustion, and cold enough coolant is available, the water can be condensed, pressurized and re-boiled for expansion in a Rankine cycle.The steam produced can be utilized in a number of ways. In this study, steam is injected through a series of de Laval nozzles directed into the main turbine, to produce extra power in a compact arrangement. To minimize the size of the system, additive manufacturing was used for the heat exchangers, giving high performance per unit volume. The study demonstrates the feasibility of the cycle in producing power from waste heat using humid gas that already is present in most applications. The experimental results show that the system is able to generate power at very low exhaust temperatures where the standard IBC would undoubtedly cease to operate. With an IBC inlet temperature of 370 °C, approximately 5 kJ/kg of specific shaft work was produced with 5 g/s of steam flow rate. At higher exhaust temperatures, the IBC and the Rankine cycle started to work together to increase the shaft power resulting in much higher specific work. At 620 °C, a specific shaft work of 41 kJ/kg was generated at a steam flow of 9 g/s. For the present turbomachinery sizes, this corresponded to 1933 W of power at 47 g/s of main exhaust flow.A model of the thermodynamic system was created in order to study the sensitivity of the system to parameters such as the steam expander pressure ratio and efficiency. Higher steam pressure and higher steam expander efficiency both led to greater power generated for the same operating point, particularly at high IBC turbine inlet temperatures. The peak specific work for the range of parameters explored in the paper was 68 kJ/kg with a steam expander efficiency of 70% and exhaust conditions of 600 °C and 50 g/s. The plots produced in this study can be used as a guide for others considering this system to understand the expected power generated under a range of conditions.
AB - Waste heat recovery is an important technology in a world with increasingly stringent emissions legislation. One such means of recovering thermal energy is the inverted Brayton cycle (IBC). This paper presents, for the first time, an experimental study of a novel combination of the IBC with a Rankine cycle. The IBC requires cooling of the exhaust gases after expansion. If the gases contain water vapour, as is the case for hydrocarbon combustion, and cold enough coolant is available, the water can be condensed, pressurized and re-boiled for expansion in a Rankine cycle.The steam produced can be utilized in a number of ways. In this study, steam is injected through a series of de Laval nozzles directed into the main turbine, to produce extra power in a compact arrangement. To minimize the size of the system, additive manufacturing was used for the heat exchangers, giving high performance per unit volume. The study demonstrates the feasibility of the cycle in producing power from waste heat using humid gas that already is present in most applications. The experimental results show that the system is able to generate power at very low exhaust temperatures where the standard IBC would undoubtedly cease to operate. With an IBC inlet temperature of 370 °C, approximately 5 kJ/kg of specific shaft work was produced with 5 g/s of steam flow rate. At higher exhaust temperatures, the IBC and the Rankine cycle started to work together to increase the shaft power resulting in much higher specific work. At 620 °C, a specific shaft work of 41 kJ/kg was generated at a steam flow of 9 g/s. For the present turbomachinery sizes, this corresponded to 1933 W of power at 47 g/s of main exhaust flow.A model of the thermodynamic system was created in order to study the sensitivity of the system to parameters such as the steam expander pressure ratio and efficiency. Higher steam pressure and higher steam expander efficiency both led to greater power generated for the same operating point, particularly at high IBC turbine inlet temperatures. The peak specific work for the range of parameters explored in the paper was 68 kJ/kg with a steam expander efficiency of 70% and exhaust conditions of 600 °C and 50 g/s. The plots produced in this study can be used as a guide for others considering this system to understand the expected power generated under a range of conditions.
M3 - Conference contribution
BT - Proceedings of ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition
ER -