Brayton thermodynamic cycle

The surprise was finally clarified by remembering that this was an air operated plant built in a thermodynamic cycle, (the Brayton or gas turbine cycle) with a 18,000 HP air compressor. This generated 5 MW of salable... 

Gas turbine systems operate on the thermodynamic cycle known as the Brayton cycle. In a Brayton cycle, atmospheric... 

On-site combined heat and power (CHP) which has existed for years, includes turbines, reciprocating engines and steam turbines. Gas turbines in the 500-kW to 250-MW produce electricity and heat using a thermodynamic cycle known as the Brayton cycle. They produce about 40,000-MW of the total CHP in the United States. The electric efficiency for units of less... 

Figure 9-15. Combined Brayton-Rankine Cycle Thermodynamics...

A recent comprehensive study [16] shows that the ideal detonative cycle is indeed more efficient than the ideal constant-volume Humphrey and the ideal constant-pressure Brayton cycles under all conditions. The relative advantage does decrease with increasing inlet compression temperature ratios and, hence, will decrease with increasing flight Mach numbers. The thermodynamic cycle efficiencies have been related to overall performance measures using conventional steady-state analysis. The appropriateness of this approach to an inherently unsteady device is debatable but is worth considering as an additional performance estimate. 

Brayton Cycle - A thermodynamic cycle using constant pressure, heat addition and rejection, representing the idealized behavior of the working fluid in a gas turbine type heat engine. 

Microturbines, pumps, and compressors are key components used to implement thermodynamic cycles for power generation, propulsion, or cooling. Thermodynamic power cycles use a working fluid that changes state (pressure and temperature) in order to convert heat into mechanical work. To achieve high power density, the pressures and temperatures of the fluid in the cycle should be kept to the high levels common at large scale. Common cycles are the Brayton gas power cycle and the Rankine vapor power cycle, described next. 

The SSTAR (24) and STAR-LM (25) lead cooled reactor concepts are based on nitride fuel and use a higher core outlet temperature to drive a supercritical CO2 Brayton cycle at 550 to 600°C, with a potential to gain energy conversion efficiencies of 43% at these temperatures. Moreover, the outlet temperature on the cool side of the recuperator can lie in the range of 70 to 125°C with only weak influence on the efficiency. As the inlet to the compressor is just above 31°C, these conditions facilitate installation of bottoming cycles for district heating, seawater desalination, or process heat production, using the heat otherwise rejected in thermodynamic cycle (see Annexes XXII and XXIII). The supercritical CO2 Brayton cycle lacks an industrial experience base this non-conventional Bra)don cycle will require R D. 

The thermodynamic cycle upon which all gas turbines operate is called the Brayton cycle. Figure 6.51 shows the classical pressure-volume (PV) and temperature-entropy (TS) diagrams for this cycle. The numbers on this diagram correspond to the nnmbers also used in Fig. 6.50. Every Brayton cycle can be characterized by two significant parameters pressure ratio... 

Thermodynamic cycle Direct gas turbine cycle (recuperated Brayton cycle) Indirect... 

Thermodynamic cycle Indirect, multi-reheat helium or nitrogen Brayton power cycle... 

In apphcation to electric utihty power generation, MHD is combined with steam (qv) power generation, as shown in Figure 2. The MHD generator is used as a topping unit to the steam bottoming plant. From a thermodynamic point of view, the system is a combined cycle. The MHD generator operates in a Brayton cycle, similar to a gas turbine the steam plant operates in a conventional Rankine cycle (11). 

Fig. 9. Brayton cycle, where A = compressor inlet, B = combustor inlet, C = power turbine inlet, and D = exhaust (a) thermodynamic relationships and...

A simplified application of the first law of thermodynamics to the air-standard Brayton cycle in Figure 2-1 (assuming no changes in kinetic and potential energy) has the following relationships ... 

The Rankine cycle diagram placed adjacent the Brayton cycle in Figure 9-15 is indicated as a simple steam cycle with superheat, but no reheat and no multi-pressure steam generation. The thermodynamic advantage of the Rankine bottoming cycle is the lowered temperature of heat rejection, in the steam condenser, from the overall combined cycles. 

The thermodynamic power cycles most commonly used today are the vapor Rankine cycle and the gas Brayton cycle (see Chapter 4). Both are characterized by two isobaric and two isentropic processes. The vapor... 

Applying the first and second laws of thermodynamics for an open system to each of the four processes of the Brayton cycle yields ... 

Determine the mass rate flow of air through the Brayton cycle, and the thermodynamic efficiency and net power output of the Brayton/ Rankine combined plant. Plot the sensitivity diagram of r] (cycle efficiency) versus pn (pressure at state 11). 

Chen, L., Sun, F., and Wu, C., Performance analysis for a real closed regenerated Brayton cycle via methods of finite-time thermodynamics. International Journal of Ambient Energy, 20(2), 95-104, 1999. 

In Fig. 30.3, the thermodynamic efficiencies of a constant-pressure Brayton cycle, a constant-volume Humphery cycle (which approximates a PDE cycle), and a true detonation Chapman-Jouguet (CJ) cycle for a typical hydrocarbon fuel are compared [11]. Though the constant-volume cycle shows substantial efficiency advantage, this zeroth order comparison cannot be taken as the correct quantitative comparison, since PDE operates in a pulsed transient mode. How-... 

Among the chemical cycles available for hydrogen production at temperatures above 1000 K, as an alternative to electricity production by a thermodynamical Brayton cycle (Sorensen, 2004a), the following set currently appears most attractive (Summers et al, 2004),... 

The higher gas density of the MCGC, relative to current combustion turbines, also reduces pressure losses in recuperators, so the MCGC adapts well to a recuperated Brayton cycle. Combustion turbines, however, must commonly use complex and expensive steam bottoming cycles to achieve thermodynamic efficiencies above 50%. 

In summary, to obtain similar thermod5mamic efficiency, it appears that nitrogen-based systems will have somewhere around 40% larger volume than helium-based systems. Their capital cost will be higher because of the less optimal thermodynamic properties of nitrogen compared with helium. However, the nitrogen-based Brayton cycle is expected to be less expensive than the equivalent Rankine steam cycle because of the low-pressure steam components and the moisture separator components required for the Rankine cycle. 

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