Relative Cooling: Part II — Design Considerations and Efficiency

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Cooling System ◽  
High Reliability ◽  
Difficult Problem ◽  
Turbine Engines ◽  
Air Cooling ◽  
Gas Turbine Engines ◽  
Coolant Pump ◽  
Cooling Systems

Abstract Cooling systems with liquid for gas turbine engines that use the relative motion of the engine stator with respect to the rotor for actuating the coolant pump can be encapsulated within the engine rotor. In this manner, the difficult problem of sealing stator/rotor interfaces at high temperature, pressure and relative velocity is circumvented. A first generation of such cooling systems could be manufactured using existing technologies and would boost the thermal efficiency of gas turbine engines by more than 2% compared to recent designs that use advanced air-cooling methods. Later, relative cooling systems could increase the thermal efficiency of gas turbine engines by 8%–11% by boosting the temperatures at turbine inlet to stoichiometric levels and recovering most of the heat extracted from turbine during cooling. The appreciated high reliability of this cooling system will allow widespread use for aerospace propulsion.

Relative Cooling System: Design and Efficiency

2003 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
First Generation ◽  
Cooling System ◽  
High Reliability ◽  
Weight Ratio ◽  
Difficult Problem ◽  
Air Cooling ◽  
Cooling Systems ◽  
Aerospace Applications

Cooling systems with liquid for gas turbines that use the relative motion of engine stator with respect to rotor have been called relative cooling systems. This motion actuates the pump for liquid recirculation and the system is encapsulated within the engine rotor. In this manner, the difficult problem of sealing stator/rotor interfaces at high temperature, pressure and relative velocity is circumvented. A first generation of such systems could be manufactured using existing technologies and would boost thermal efficiency of gas turbines by more than 3% compared to the most advanced air-cooling engines. In the end, relative systems would boost temperatures at turbine inlet to stoichiometric levels and therefore increase thermal efficiency of gas turbines by about 8%. Such systems would recover most heat extracted from turbine for cooling and increase the power to size and power to weight ratio of all gas turbines. The appreciated high reliability of this cooling relies on encapsulation within the rotor and will allow widespread use in both ground and aerospace applications.

Exceeding 2000 K at Turbine Inlet: Relative Cooling With Liquid for Gas Turbines — Integrated Systems

2003 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Gas Turbine ◽  
Relative Motion ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
State Of The Art ◽  
Cooling System ◽  
Ambient Air ◽  
Air Cooling ◽  
Cooling Systems ◽  
Turbine Inlet

Thermal efficiency of gas turbines is critically dependent on temperature of burnt gases at turbine inlet, the higher this temperature the higher the efficiency. Stochiometric combustion would provide maximum efficiency, but in the absence of an internal cooling system, turbine blades cannot tolerate gas temperatures exceeding 1300 K. This temperature yields a low thermal efficiency, about 15% below the level provide by stoicthiometric combustion. Conventional engines rely on air for blade and disk cooling and limit temperature at turbine inlet to about 1500 K. These engines gain about 3% compared to non-cooled designs. Gas turbines with state of the art air-cooling systems reach up to 1700–1750 K, boosting thermal efficiency by another 2–3%. These temperatures are near the limit allowed by air-cooling systems. Cooling systems with air are easier to design, but air has a low heat transfer capacity, and compressor air bleeding lowers the overall efficiency of engines (less air remains available for combustion). In addition, these systems waste most of the heat extracted from turbine for cooling. In principle, gas turbines could be cooled with liquid. Half a century ago, designers tried to place the pump for coolant recirculation on the engine stator. Liquid was allowed to boil inside the turbine. Seals for parts in relative motion cannot prevent loss of superheated vapors, therefore these experiments failed. To circumvent this problem, another design relied on thermal gradients to promote recirculation from blade tip to root. Liquid flow and cooling capacity were minute. Therefore it was assumed that liquid couldn’t be used for gas turbine cooling. This is an unwarranted assumption. The relative motion between engine stator and rotor provides abundant power for pumps placed on the rotor. The heat exchanger needed for cooling the liquid with ambient air could also be embedded in the rotor. In fact, the entire cooling system can be encapsulated within the rotor. In this manner, the sealing problem is circumvented. Compared to state of the art air-cooling methods, such a cooling system would increase thermal efficiency of any gas turbine by 6%–8%, because stoichimoetric fuel-air mixtures would be used (maybe even with hydrogen fuel). In addition, these systems would recuperate most of the heat extracted from turbine for cooling, are expected to be highly reliable and to increase specific power of gas turbines by 400% to 500%.

scholarly journals ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТД ХОЛОДИЛЬНИМИ МАШИНАМИ ШЛЯХОМ АКУМУЛЯЦІЇ ХОЛОДУ

2020 ◽  
pp. 22-27
Author(s):  
Андрій Миколайович Радченко ◽  
Богдан Сергійович Портной ◽  
Сергій Анатолійович Кантор ◽  
Олександр Ігорович Прядко ◽  
Іван Володимирович Калініченко
Keyword(s):  
Gas Turbine ◽  
Cooling System ◽  
Turbine Engines ◽  
Air Cooling ◽  
Gas Turbine Engines ◽  
Cooling Stage ◽  
Exhaust Heat ◽  
Air Cooling System ◽  
Refrigeration Capacity ◽  
Heat Loads

The efficiency of air cooling at the inlet of gas turbine engines by exhaust heat conversion chiller, which transforms the GTE exhaust gases heat into cold, under variable climatic operating conditions, has been investigated. Considered is the use of a combined absorption-ejector exhaust heat conversion chiller with a step-by-step principle of air cooling at the gas turbine engines inlet: preliminary down to 15°C – by an absorption lithium-bromide chiller (ACh), which is used as a high-temperature air cooling stage, and further cooling down to 10°C – by a refrigerant ejector chiller (ECh) as a low-temperature cooling stage. Reserves have been identified for reducing the design (installed) refrigeration capacity of chillers by accumulating excess cold at reduced current heat loads with its use at increased heat loads. In this case, the design (installed) refrigeration capacity of chillers was determined by two methods: the first – based on the close to the maximum reduction in annual fuel consumption, the second – according to the maximum rate of increase in the reduction in annual fuel consumption. A scheme of the air cooling system at the gas turbine engines inlet using the refrigeration capacity reserve of the ACh, which provides preliminary cooling of the ambient air at the gas turbine engines inlet, in the booster stage, using the ACh accumulated excess refrigeration capacity has been proposed. The ACh excess refrigerating capacity, which is formed at decreased heat loads on the air coolers at the gas turbine engines inlet, is accumulated in the cold accumulator and is used at increased heat loads. The simulation results show the advisability of using the air cooling system at the gas turbine engine inlet with using the ACh accumulated excess refrigeration capacity, which allows reducing the ACh design (installed) refrigeration capacity by approximately 40%.

Effect of New Blade Cooling System With Minimized Gas Temperature Dilution on Gas Turbine Performance

1984 ◽  
Vol 106 (4) ◽  
pp. 756-764 ◽  
Author(s):  
K. Kawaike ◽  
N. Kobayashi ◽  
T. Ikeguchi
Keyword(s):  
Gas Turbine ◽  
Cooling System ◽  
High Reliability ◽  
Pressure Ratio ◽  
Growth Potential ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Cooling Systems ◽  
Blade Cooling ◽  
Turbine Performance

Recent developments in high-performance and high-reliability gas turbine engines necessitate enforced cooling to maintain the blade temperature at reasonably low levels associated with increased turbine inlet temperature and compressor pressure ratio. However, the gas turbine performance is strongly penalized by the consumption of cooling flow, resulting in temperature dilution of hot mainstream, aerodynamic mixing loss, and pumping power loss. In this paper, a new practical blade cooling system using state-of-the-art engineering, which aims at minimizing the dilution effect, is presented. Trade-off studies between performance and reliability in terms of blade metal temperature are performed to evaluate cooling systems. Analytical comparison of different cooling systems demonstrates that the proposed cooling system provides significant improvements in performance gain and growth potential over conventional air cooling systems.

Thermodynamic Performance of Complex Gas Turbine Cycles

2002 ◽  
Author(s):  
Sanjay ◽  
Onkar Singh ◽  
B. N. Prasad
Keyword(s):  
Gas Turbine ◽  
Specific Power ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Gas Turbine Engines ◽  
Current State ◽  
Thermodynamic Performance ◽  
Internal Convection ◽  
Plant Efficiency

This paper deals with the thermodynamic performance of complex gas turbine cycles involving inter-cooling, re-heating and regeneration. The performance has been evaluated based on the mathematical modeling of various elements of gas turbine for the real situation. The fuel selected happens to be natural gas and the internal convection / film / transpiration air cooling of turbine bladings have been assumed. The analysis has been applied to the current state-of-the-art gas turbine technology and cycle parameters in four classes: Large industrial, Medium industrial, Aero-derivative and Small industrial. The results conform with the performance of actual gas turbine engines. It has been observed that the plant efficiency is higher at lower inter-cooling (surface), reheating and regeneration yields much higher efficiency and specific power as compared to simple cycle. There exists an optimum overall compression ratio and turbine inlet temperature in all types of complex configuration. The advanced turbine blade materials and coating withstand high blade temperature, yields higher efficiency as compared to lower blade temperature materials.

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