The Use of Ejector Refrigeration Systems for Turbine Inlet Air Cooling: A Thermodynamic and CFD Study

2007 ◽  
Author(s):  
Hany A. Al-Ansary
Keyword(s):  
Power Consumption ◽  
Power Output ◽  
Waste Heat ◽  
Evaporative Cooling ◽  
Published Data ◽  
Air Cooling ◽  
Refrigeration System ◽  
Compressor Blades ◽  
Cooling Systems ◽  
Turbine Inlet

Cooling turbine inlet air is a proven method of increasing turbine power output, especially during peak summer demand. It is estimated that turbine power output can increase by as much as 0.7% for every 1°C drop in inlet air temperature. Two inlet air cooling systems are widely used: evaporative cooling systems and chiller systems. Evaporative cooling is economical and uncomplicated, but its efficiency can significantly drop if the relative humidity is high. There is also a potential for excessive wear of compressor blades if water droplets are carried into the compressor section. On the other hand, chiller systems have the advantage of being independent of humidity and do not have the potential to cause damage to compressor blades. However, chiller systems consume power and cause a larger pressure drop than evaporative coolers. In this work, the possibility of using an ejector refrigeration system to cool turbine inlet air is explored. These systems are low-maintenance, fluid-driven, heat-operated devices that can use part of the turbine exhaust flow as the heat source for running the cycle. These systems require only pump power to feed liquid refrigerant to the vapor generator, making the power consumption potentially lower than conventional chiller systems. Using thermodynamic analysis, this paper compares the performance of ejector refrigeration systems with that of chiller systems based primarily on their power consumption. Performance characteristics for the ejector system are obtained through a CFD model that uses a real-gas model for R-134a. Published data on the performance of a commercial gas turbine is also considered. The power consumption of ejector refrigeration systems is found to be significantly smaller than that of vapor compression systems, with savings ranging from 19% to 80%. Power consumption is also found to be small compared to the boost in turbine power that is obtained. The percentage of waste heat needed to operate the ejector refrigeration system is found to be generally less than 25%.

Systematic Assessment of Combustion Turbine Inlet Air-Cooling Techniques

2005 ◽  
Vol 127 (1) ◽  
pp. 159-169 ◽  
Author(s):  
Abdalla M. Al-Amiri ◽  
Montaser M. Zamzam
Keyword(s):  
Air Temperature ◽  
Evaporative Cooling ◽  
Heat Rate ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Wide Range ◽  
The Impact

The current study is centered on assessing the benefits of incorporating combustion turbine inlet air-cooling systems into a reference combustion turbine plant, which is based on a simple cycle under base load mode. Actual climatic conditions of a selected site were examined thoroughly to identify the different governing weather patterns. The main performance characteristics of both refrigerative and evaporative cooling systems were explored by examining the effect of several parameters including inlet air temperature, airflow-to-turbine output ratio, coefficient of performance (for refrigerative cooling systems), and evaporative degree hours (for evaporative cooling systems). The impact of these parameters was presented against the annual gross energy increase, average heat rate reduction, cooling load requirements and net power increase. Finally, a feasibility design chart was constructed to outline the economic returns of employing a refrigerative cooling unit against different prescribed inlet air temperature values using a wide range of combustion turbine mass flow rates.

Inlet Air Cooling Methods for Gas Turbine Based Power Plants

2004 ◽  
Author(s):  
E. Kakaras ◽  
A. Doukelis ◽  
A. Prelipceanu ◽  
S. Karellas
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Evaporative Cooling ◽  
Climatic Conditions ◽  
Combined Cycle ◽  
Air Cooling ◽  
Cooling Systems ◽  
Cooling Methods

Power generation from gas turbines is penalised by a substantial power output loss with increased ambient temperature. By cooling down the gas turbine intake air, the power output penalty can be mitigated. The purpose of this paper is to review the state of the art in applications for reducing the gas turbine intake air temperature and examine the merits from integration of the different air-cooling methods in gas turbine based power plants. Three different intake air-cooling methods (evaporative cooling, refrigeration cooling and evaporative cooling of pre-compressed air) have been applied in two combined cycle power plants and two gas turbine plants. The calculations were performed on a yearly basis of operation, taking into account the time-varying climatic conditions. The economics from integration of the different cooling systems were calculated and compared.

Inlet Air Cooling Applied to Combined Cycle Power Plants: Influence of Site Climate and Thermal Storage Systems

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi
Keyword(s):  
Power Output ◽  
Parametric Analysis ◽  
Power Plants ◽  
Cooling System ◽  
Thermal Storage ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Cooling Systems

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during the night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both cool thermal storage technologies considered perform similarly in terms of gross extra production of energy. Despite this, the ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of the plant site resulted in a greater increase in the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important the size of inlet cooling storage may be for economical results.

scholarly journals Performance Characteristics of Solid-Desiccant Evaporative Cooling Systems

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2574 ◽  
Author(s):  
Ramadas Narayanan ◽  
Edward Halawa ◽  
Sanjeev Jain
Keyword(s):  
Air Conditioning ◽  
Natural Ventilation ◽  
Waste Heat ◽  
Numerical Study ◽  
Evaporative Cooling ◽  
Peak Load ◽  
Dew Point ◽  
Low Grade ◽  
Subtropical Climate ◽  
Cooling Systems

Air conditioning accounts for up to 50% of energy use in buildings. Increased air-conditioning-system installations not only increase total energy consumption but also raise peak load demand. Desiccant evaporative cooling systems use low-grade thermal energy, such as solar energy and waste heat, instead of electricity to provide thermal comfort. This system can potentially lead to significant energy saving, reduction in carbon emissions, and it has a low dew-point operation and large capacity range. Their light weight, simplicity of design, and close-to-atmospheric operation make them easy to maintain. This paper evaluates the applicability of this technology to the climatic conditions of Brisbane, Queensland, Australia, specifically for the residential sector. Given the subtropical climate of Brisbane, where humidity levels are not excessively high during cooling periods, the numerical study shows that such a system can be a potential alternative to conventional compression-based air-conditioning systems. Nevertheless, the installation of such a system in Brisbane’s climate zone requires careful design, proper selection of components, and a cheap heat source for regeneration. The paper also discusses the economy-cycle options for this system in such a climate and compares its effectiveness to natural ventilation.

Relative Cooling With Liquid for Gas Turbines: Part I — A Solution for Exceeding 2000 K at Turbine Inlet

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Cooling Methods ◽  
Current Operating

Abstract The thermal efficiency of gas turbines is critically dependent on the 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 that exceed 1300 K. Therefore, for this temperature, the thermal efficiency of turbine engine is 40% less than theoretical maximum. Conventional air-cooling techniques of turbine blades allow inlet temperatures of about 1500 K on current operating engines yielding thermal efficiency gains of about 6%. New designs, that incorporate advanced air-cooling methods allows inlet temperatures of 1750–1800 K, with a thermal efficiency gain of about 6% relative to current operating engines. This temperature is near the limit allowed by air-cooling systems. Turbine blades can be cooled with air taken from the compressor or with liquid. Cooling systems with air are easier to design but have a relatively low heat transfer capacity and reduce the efficiency of the engine. Some cooling systems with liquid rely on thermal gradients to promote re-circulation from the tip to the root of turbine blades. In this case, the flow and cooling of liquid are restricted. For best results, cooling systems with liquid should use a pump to re-circulate the coolant. In the past, designers tried to place this pump on the engine stator and therefore were unable to avoid high coolant losses because it is impossible to reliably seal the stator-rotor interface. Therefore it was assumed that cooling systems with liquid could not incorporate pumps. This is an unwarranted assumption as shown studying the system in a moving frame of reference that is linked to the rotor. Here is the crucial fact overlooked by previous designers. The relative motion of engine stator with respect to the rotor is sufficient to motivate a cooling pump. Both the pump and heat exchange system that is required to provide rapid cooling of liquid with cold ambient air, could be located within the rotor. Therefore, the entire cooling system can be encapsulated within the rotor and the sealing problem is circumvented. Compared to recent designs that use advanced air-cooling methods, such a liquid cooling system would increase the thermal efficiency by 8%–11% because the temperatures at turbine inlet can reach stoichiometric levels and most of the heat extracted from turbine during cooling is recuperated. The appreciated high reliability of the system will permit a large applicability in aerospace propulsion.

Analysis of novel regenerative thermo-mechanical refrigeration system integrated with isobaric engine

2020 ◽  
pp. 1-27
Author(s):  
Ahmad K. Sleiti ◽  
Wahib Al-Ammari ◽  
Mohammed Al-Khawaja
Keyword(s):  
Heat Source ◽  
Environmental Effects ◽  
Power Efficiency ◽  
Waste Heat ◽  
Working Fluid ◽  
Refrigeration System ◽  
Cooling Systems ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature

Abstract Refrigerants of the conventional cooling systems contribute to global warming and ozone depletion significantly, therefore it is necessary to develop new cooling systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. To address this, the present study introduces and analyzes a novel regenerative thermo-mechanical refrigeration system that can be powered by renewable heat sources (solar, geothermal, or waste heat). The system consists of a novel expander-compressor unit (ECU) integrated with a vapor compression refrigeration system. The integrated system operates at the higher-performance supercritical conditions of the working fluids as opposed to the lower-performance subcritical conditions. The performance of the system is evaluated based on several indicators including the power loop efficiency, the coefficient of performance (COP) of the cooling loop, and the expander-compressor diameters. Several working fluids were selected and compared for their suitability based on their performance and environmental effects. It was found that for heat source temperature below 100 °C, adding the regenerator to the system has no benefit. However, the regenerator increases the power efficiency by about 1 % for a heat source temperature above 130 °C. This was achieved with a very small size regenerator (Dr = 6.5 mm, Lr = 142 mm). Results show that there is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at heat source temperature Th=150 °C and cold temperature Tc1=40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm, and compressor diameter of 75.4mm.

scholarly journals Benefits of Compressor Inlet Air Cooling for Gas Turbine Cogeneration Plants

1995 ◽  
Author(s):  
Maurizio De Lucia ◽  
Carlo Lanfranchi ◽  
Vanni Boggio
Keyword(s):  
Gas Turbine ◽  
Performance Enhancement ◽  
Evaporative Cooling ◽  
Economic Benefits ◽  
Data Series ◽  
Air Cooling ◽  
Climatic Data ◽  
Cooling Systems ◽  
Compressor Inlet ◽  
Base Load

Compressor inlet air cooling is an effective method for enhancing the performance of gas turbine plants. This paper presents a comparative analysis of different solutions for cooling the compressor inlet air for the LM6000 gas turbine in a cogeneration plant operated in base load. Absorption and evaporative cooling systems are considered and their performance and economic benefits compared for the dry low-NOx LM6000 version. Reference is made to two sites in Northern and Southern Italy, whose climatic data series for modeling the variations in ambient temperature during the single day were used, to account for the effects of climate in the simulation. The results confirmed the advantages of inlet air cooling systems. In particular, evaporative cooling proved to be cost-effective, though capable of supplying only moderate cooling, while absorption systems have a higher cost but are also more versatile and powerful in base load operation. An integration of the two systems proved to be able to give both maximum performance enhancement and net economic benefit.

scholarly journals Energy-focused substantiation of the choice of an air conditioning system for an office and shopping building

2021 ◽  
Vol 11 (2) ◽  
pp. 38-45
Author(s):  
Anastasiya A. Frolova ◽  
◽  
Pavel I. Lukhmenev ◽  
Keyword(s):  
Power Consumption ◽  
Air Conditioning ◽  
Large Scale ◽  
Cooling System ◽  
Air Cooling ◽  
Outdoor Temperature ◽  
Cooling Systems ◽  
Air Conditioning System ◽  
Northern Areas ◽  
Conventional Cooling

Introduction. The air conditioning system is the main consumer of electricity inside office and shopping buildings. The coo­ling needs arise inside such buildings all over the year due to high amounts of heat emitted by people and equipment (computers, office equipment, cash registers), solar radiation (the envelopes of the majority of these buildings have continuous glazed facades) and sources of artificial lighting. A conventional cooling system has a compressor and condensers. The most important step towards an optimized and low-energy cooling system is the abandonment of compressor and condensers; in addition, the cold extracted from the outdoor air, is used in the system. This cooling technique is called an atmospheric co­oling system. The climatic features of Russia allow for a large-scale application of the cooling technology that uses natural cold. However, for a start, a decision was made to focus on a central region of the Russian Federation, namely, Moscow, rather than any northern areas of the country. Materials and methods. The problem is solved by the calculation method applied to the case of a 35-storey office building in Moscow. Various outdoor temperature options were considered as the bases for a transition to an atmospheric cooling system. The co-authors also compare different installation options for dry coolers, which in turn affect the routing length of refrigeration circuits. The annual demand for cold is calculated for all analyzed options. Results. Some results are presented in the form of tables of annual energy consumption by different types of air cooling systems. Conclusions. The co-authors have found that the location of dry coolers strongly affects the power consumption by a co­oling system. Power consumption by cooling systems was analyzed, and it was found out that transition to machine refrigeration at the higher outdoor temperature of +8 °C is more efficient from the standpoint of energy efficiency than the same transition at +5 and 0 °C.

Benefits of Compressor Inlet Air Cooling for Gas Turbine Cogeneration Plants

1996 ◽  
Vol 118 (3) ◽  
pp. 598-603 ◽  
Author(s):  
M. De Lucia ◽  
C. Lanfranchi ◽  
V. Boggio
Keyword(s):  
Gas Turbine ◽  
Performance Enhancement ◽  
Evaporative Cooling ◽  
Economic Benefits ◽  
Data Series ◽  
Air Cooling ◽  
Climatic Data ◽  
Cooling Systems ◽  
Compressor Inlet ◽  
Base Load

Compressor inlet air cooling is an effective method for enhancing the performance of gas turbine plants. This paper presents a comparative analysis of different solutions for cooling the compressor inlet air for the LM6000 gas turbine in a cogeneration plant operated in base load. Absorption and evaporative cooling systems are considered and their performance and economic benefits compared for the dry low-NOx LM6000 version. Reference is made to two sites in Northern and Southern Italy, whose climatic data series for modeling the variations in ambient temperature during the single day were used to account for the effects of climate in the simulation. The results confirmed the advantages of inlet air cooling systems. In particular, evaporative cooling proved to be cost effective, though capable of supplying only moderate cooling, while absorption systems have a higher cost but are also more versatile and powerful in base-load operation. An integration of the two systems proved to be able to give both maximum performance enhancement and net economic benefit.

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