Turbine Inlet Air Cooling Research Articles

Techno-Economic Feasibility Study of Earth Air Heat Exchangers for Gas Turbine Inlet Air Cooling

In response to pressing energy crises and environmental concerns, enhancing the performance of existing energy conversion systems, such as gas turbines, and tapping into renewable resources have become critical imperatives. Escalating ambient temperatures poses a notable challenge, hampering the efficiency of gas turbines. This study rigorously explores the feasibility of earth-to-air heat exchangers (EAHEs) as a pragmatic solution to cool gas turbine inlet air. The primary objective is an exhaustive techno-economic analysis evaluating the long-term operational viability of EAHE systems. Employing the Taguchi method, the study optimizes the system geometry and pipe arrangement, focusing on four key control factors: pipe diameter, spacing, length, and depth. The pivotal optimization criterion is the levelized cost of energy (LCOE), encompassing thermal performance and economic viability. The net present value (NPV) and Discounted Payback Period provide supplementary insights into the economic prospects. Integral to the study is a novel and intricate hybrid analytical-numerical model that simulates the long-term transient operation of EAHE. Findings from a detailed case study unveil an optimized scenario yielding an LCOE amounting to 0.071 $/kWh, accompanied by a substantial NPV of 4.5 million dollars.

Comparative Analysis of Environmental Sustainability and Performance Indices of Different Gas Turbine Inlet Cooling Systems

Comparative Analysis of Environmental Sustainability and Performance Indices of Different Gas Turbine Inlet Cooling Systems

Analysis of Chilled Water Turbine Inlet Air Cooling Model for Enhancement of Turbine Performance

Analysis of Chilled Water Turbine Inlet Air Cooling Model for Enhancement of Turbine Performance

Performance enhancements and NOx emission reductions using novel exhaust-driven hybrid gas turbine inlet air-cooling techniques

For combined cycles, gas turbine inlet air-cooling (GTIAC) increases the mass flow rates of both air and the generated steam of the heat recovery steam generator and hence power output. The introduction of exhaust gas recirculation (EGR) to reduce NOx emissions necessitates the application of GTIAC to overcome the adverse effects of gas turbine (GT) inlet air heating that accompany EGR. For a hot-humid climate, the r5egular cooling methods consume a significant amount of energy while desiccant and inlet-fogging are not effective. The main purpose of this study is to introduce innovative exhaust-driven hybrid GTIAC techniques that can reduce effectively the inlet temperature of the combined cycle in a hot-humid climate without consuming a substantial amount of energy and examine the effects of applying such techniques on the performance and NOx emissions. In this paper, a thorough analysis for the effect of increasing ambient temperature ( To) and relative humidity ( RHo) on the performance and NOx emissions of the air-cooled GT combined cycle (ACGTCC) is presented and the novel exhaust-driven hybrid (NE-DH) GTIAC systems of desiccant-ejector, ejector-refrigeration, and desiccant-ejector-refrigeration are applied to ACGTCC and optimized for maximum power output. The 1-D model at the double choking was used to model the performance of the ejector GTIAC technique. The results indicate that applying NE-DH GTIAC techniques results in gains in power, which vary between 0.31% and 0.6% per °C rise in To and an efficiency improvement of up to about 0.5 percentage point and significant reductions in both capital and maintenance costs compared with applying the refrigeration GTIAC system. The introduction of ejector and desiccant cooling decreases NOx emissions further and adds no additional equipment cost if implemented together with EGR or some CO2 capture techniques. A suggested plan for GTIAC that reduces NOx emissions by up to 25% is presented.

A review of gas turbine inlet cooling technologies

Gas turbine (GT) performance is primarily dependent on the inlet air temperature. The power output of gas turbine is dependent on the flow of mass through the gas turbine. This is why at hot weathers with less dense air, the power output drops, but at cold weather with high dense air, the power output rises. The inlet air cooling (IAC) technology is one of the major drivers that enhance the gas turbine performance, especially during the hot weathers. The performance of gas turbine is affected by various factors such as inlet air cooling, fuel type, fuel heating value, air temperature, turbine inlet temperature, humidity, site elevation, inlet and exhaust losses, air extraction, diluent injection, performance degradation, etc. The aim of this technical review is based on the comparative analysis of different gas turbine inlet air cooling (GTIAC) technologies and its applications based on the climate conditions. The power consumption due to inlet air cooling calls for major concern since it reduces the GT net power output. Different GTIAC has its unique benefits and challenges. The biggest gains from evaporative cooling are achieved during hot, low-humidity climates. Furthermore, the review paper showed that the efficiency of the evaporative cooler is majorly dependent on the moisture present in the air. The work also reveals that the feasibility of each GTIAC application is basically dependent on the location.

Increasing the Efficiency of Turbine Inlet Air Cooling in Climatic Conditions of China through Rational Designing—Part 1: A Case Study for Subtropical Climate: General Approaches and Criteria

The enhancement of gas turbine (GT) efficiency through inlet air cooling, known as TIAC, in chillers using the heat of exhaust gas is one of the most attractive tendencies in energetics, particularly in thermal engineering. In reality, any combustion engine with cyclic air cooling using waste heat recovery chillers might be considered as a power plant with in-cycle trigeneration focused on enhancing a basic engine efficiency, which results in additional power output or fuel savings, reducing carbon emissions in all cases. The higher the fuel efficiency of the engine, the more efficient its functioning as a source of emissions. The sustainable operation of a GT at stabilized low intake air temperature is impossible without using rational design to determine the cooling capacity of the chiller and TIAC system as a whole to match current duties without overestimation. The most widespread absorption lithium-bromide chillers (ACh) are unable to reduce the GT intake air temperature below 15 °C in a simple cycle because the temperature of their chilled water is approximately 7 °C. Deeper cooling air would be possible by applying a boiling refrigerant as a coolant in ejector chiller (ECh) as the cheapest and simplest in design. However, the coefficients of performance (COP) of EChs are considerably lower than those of AChs: about 0.3 compared to 0.7 of AChs. Therefore, EChs are applied for subsequent cooling of air to less than 15 °C, whereas the efficient ACh is used for ambient air precooling to 15 °C. The application of an absorption–ejector chiller (AECh) enables deeper inlet air cooling and greater effects accordingly. However, the peculiarities of the subtropical climate, characterized by high temperature and humidity and thermal loads, require extended analyses to reveal the character of thermal load and to modify the methodology of designing TIAC systems. The advanced design methodology that can reveal and thereby forecast the peculiarities of the TIAC system’s thermal loading was developed to match those peculiarities and gain maximum effect without oversizing.

Using of saltwater to increase the output power of a steam injected gas turbine (STIG) by connecting spray freezing desalination to it

Gas turbines are one of the common methods for generating electrical energy. However, reducing the output power by increasing the air temperature is one of the problems of these turbines. Common methods to compensate for the power drop of gas turbines are often based on turbine inlet air cooling (TIAC) technology or injecting steam or water into the turbine as humidified gas turbine (HGT) that causes an increase in its output power. However, these technologies often require high consumption of fresh water which limits their use in dry and low-water areas. Therefore this study has investigated the connection of a spray freezing desalination to a steam-injected gas turbine (STIG) through a reverse Brayton cycle for increasing its output power by consuming saltwater. This spray freezing desalination is a process based on eutectic freeze crystallization (EFC) technology that uses compressed air in a turbo expander to produce chilled air that can crystallize the droplet of sprayed saline water. This desalination technology has the potential of zero liquid discharge (ZLD). Therefore, with the possibility of using a saline water source such as reverse osmosis (RO) brine in this process, in addition to increasing the output power of gas turbines, it will be possible to reduce the environmental problems related to its disposal.

Rational loads of turbine inlet air absorption-ejector cooling systems

An increase in gas turbine efficiency is possible by inlet air cooling in chillers converting a heat of exhaust gas into refrigeration. In traditional absorption lithium-bromide chillers of a simple cycle an inlet air can be cooled to 15°С. More decrease of turbine inlet air temperature and greater fuel saving accordingly is possible in refrigerant ejector chiller as a simple in design and cheap. The innovative turbine inlet air cooling (TIC) system with absorption chiller as a high-temperature and ejector chiller as a low-temperature stages for cooling air to 7 or 10 °C is proposed. Its application in temperate climate provides annual fuel saving by 1.5 to 2 times higher compared with traditional air cooling in absorption chiller to 15 °C. A novel universal method of analysing the efficiency of TIC system operation and rational designing has been developed. The method involves the simple numerical simulation based on real input data of site actual climatic conditions. The annual fuel saving is chosen as a primary criterion. The novelty of the methodological approach consists in replacing the current yearly changeable fuel reduction due to TIC by its hour-by-hour summation as an annual fuel saving. The increment of annual fuel saving referred to needed refrigeration capacity of TIC system is used as an indicator to select a design refrigeration capacity. A rational design refrigeration capacity determined by applying the novel methodology allows to decrease the TIC system sizes by 10 to 20% compared with traditional designing issuing from the peaked thermal load during a year. So far as it was developed analytically by introducing quite reasonable criterion indicator and based on the simple summation procedure the method is quite applicable for designing in power and energy.

Performance Analysis of Gas Turbine Inlet Air Cooling Plant with Hybrid Indirect Evaporative Cooling and Absorption Chiller System

To generate electricity, Gas Turbine Power Plants are extensively used around the world but their efficiency is negatively affected on hot days by ambient air temperatures. efficiency and output power will decrease by 2% and 12.5% respectively at ambient temperature 40°C due to lower air density and the resulting increase in compressor specific work. 
 Ordinarily, cooling down the intake air of the gas turbine is facilitated by employing a variety of Turbine Inlet Air cooling Systems (TIACSs), depending on the plant’s immediate weather conditions. This paper studies a new hybrid cooling method, combined cooling systems (IECS + Absorption Chiller), used for a 157 MW gas power plant located in Asalouyeh in southern Iran. The Performance and Thermo-Economic analysis revealed that the annual power output can be 62,090 MW, the net income generated by the increased electricity sales can be $ 3,670,000 for a 60% period of the year while Payback Period is found to be 1.56 years.

A technical-economic analysis of turbine inlet air cooling for a heavy duty gas turbine operating with blast-furnace gas

The study was developed inside an integrated steel mill, located in Rio de Janeiro city, aiming to analyse the technical-economic feasibility of installing a new inlet air refrigeration system for the gas turbines. The technologies applied for such purpose are named Turbine Inlet Air Cooling (TIAC) technologies. The power plant utilizes High Fogging and Evaporative Cooling methods for reducing the compressor’s inlet air temperature, however, the ambient climate condition hampers the turbine’s power output when considering its design operation values. Hence, this study was proposed to analyse the installation of an additional cooling system. The abovementioned power plant has two heavy-duty gas turbines and one steam turbine, connected in a combined cycle configuration. The cycle nominal power generation capacity is 450 MW with each of the gas turbines responsible for 90 MW. The gas turbines operate with steelwork gases, mainly blast furnace gas (BFG), and natural gas. The plant has its own weather station, which provided significant and precise data regarding the local climate conditions over the year of 2017. An in-house computer model was created to simulate the gas turbine power generation and fuel consumption considering both cases: with the proposed TIAC system and without it, allowing the evaluation of the power output increase due to the new refrigeration system. The results point out for improvements of 4.22% on the power output, corresponding to the electricity demand of approximately 32960 Brazilian homes per month or yearly earnings of 3.92 million USD.

Exergetic and Exergoeconomic Optimization of Gas Turbine Inlet Air Cooling Systems with Absorption or Compression Chilling

The present paper aims to study the effect of cooling air inlet methods on gas turbine compressors on increasing their efficiency. After modeling gas turbine cycles with absorption and compression systems in the EES software, these cycles' performance is investigated for all equipment of the cycle from thermodynamic, exergy, and exergoeconomic aspects. In the absorption system, the conventional solution of lithium bromide-water is used as a two-component fluid, and in the compression cycle, the R134a operating fluid is used. According to the results, with the rise in the system's inlet air temperature, the total output work of the gas turbine decreases. Based on the exergoeconomic analysis, the exergy destruction cost dominates the initial cost, resulting in the exergoeconomic factor's decline. Relationship predicted by Group Method of Data Handling (GMDH) to reduce the computation time of optimization. The studied systems are then subjected to two-objective optimization by the Particle Swarm algorithm using MATLAB software. The objective functions are related to the exergy efficiency and total cost rate. The results reveal contradictory behavior in these two objective functions so that with the increase in the exergy efficiency, the total cost rate increases.

Chilled Coil Performance Control and Application to Turbine Inlet Air Cooling

The Absorption Refrigeration Cycle Turbine Inlet Conditioning (ARCTIC) system can chill the inlet air of the turbine to maintain optimum turbine performance at all ambient temperatures. However, turbine characteristics and bell-mouth icing concerns impose a minimum temperature limitation on the chilled air. Performance guarantees may also require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions and the development of a robust controls strategy. A modified wet-surface model is used to model the chilling coil performance. The application of the model to a 2110[Formula: see text]kW (600 RT) ARCTIC providing inlet air chilling for a MARS 100 turbine is considered. A control strategy is developed to maintain the inlet air temperature at the desired set point with varying ambient temperatures and chilling loads. The TIAC controls help maintain the inlet air temperature at 7.22∘C to maximize turbine capacity and efficiency during most of the hot/warm days and accommodates 100% turndown. Additional safety measures are incorporated to prevent bell-mouth icing.

Two-Stage Evaporative Inlet Air Gas Turbine Cooling

Gas turbine inlet air-cooling (TIAC) is an established technology for augmenting gas turbine output and efficiency, especially in hot regions. TIAC using evaporative cooling is suitable for hot, dry regions; however, the cooling is limited by the ambient wet-bulb temperature. This study investigates two-stage evaporative TIAC under the harsh weather of Riyadh city. The two-stage evaporative TIAC system consists of indirect and direct evaporative stages. In the indirect stage, air is precooled using water cooled in a cooling tower. In the direct stage, adiabatic saturation cools the air. This investigation was conducted for the GE 7001EA gas turbine model. Thermoflex software was used to simulate the GE 7001EA gas turbine using different TIAC systems including evaporative, two-stage evaporative, hybrid absorption refrigeration evaporative and hybrid vapor-compression refrigeration evaporative cooling systems. Comparisons of different performance parameters of gas turbines were conducted. The added annual profit and payback period were estimated for different TIAC systems.

Modified Chilled Coil Model Development and Application to Turbine Inlet Air Cooling

A Turbine Inlet Air Conditioning (TIAC) system can chill the inlet air of the turbine to maintain maximum turbine performance at all ambient temperatures. However, turbine characteristics, performance guarantees and bell-mouth icing considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions. A modified wet-surface model (MWSM) is developed to more accurately predict the chilling coil performance. The higher accuracy of the model is demonstrated by applying the model to simulate performance data of two different coils. The data covered a wide range of operating conditions with ambient temperature vary from [Formula: see text]C to [Formula: see text]C dry bulb and [Formula: see text]C to [Formula: see text]C wet bulb. The turbine flow rate varies from 100% to 43% with chilled air temperature in the range of 3.3–[Formula: see text]C and chilling load variation of 100% to 5%. The chilled water flow rate varies from 100% to 32% with supply glycol-water temperature in the range of [Formula: see text]2.2–[Formula: see text]C. The MWSM uses 11 empirical parameters evaluated from the coil performance data and is able to correlate the data with an adjusted coefficient of determination ([Formula: see text]) of over 99%. The higher accuracy of the modified model enables the development of a more robust controls strategy required to maintain the inlet air temperature at the set point with varying ambient temperatures and chilling load conditions. The model can also be applied to other chilling and dehumidification applications especially those experiencing wide variations in operating conditions and load or those requiring close control of the chilling and dehumidification process.

Thermodynamic analysis of a gas turbine inlet air cooling and recovering system in gas turbine and CO2 combined cycle using cold energy from LNG terminal

Research on the CO2 cycle has been conducted in various fields, such as nuclear power plants, centralized solar power plants, coal-fired power plants, waste heat recovery, combined cycle, and LNG cold energy recovery. In contrast to the steam Rankine cycle, the CO2 cycle is able to utilize the sub-zero temperature heat sink using LNG cold energy. Inthis study, a novel configuration is proposed that the gas turbine-carbon dioxide combined cycle power plant (GT-CO2 CCPP) with a gas turbine inlet air cooling (TIAC) and heat recovering (HR) system when using LNG cold energy. The TIAC and HR system cools the gas turbine inlet air using condensate CO2 to enhance the power output while air energy is simultaneously recovered to the CO2 bottoming cycle for additional power output and higher efficiency. To determine the capacity of this type of plant, the most commonly implemented LNG terminal is investigated, and the 62 MW medium-size gas turbine is selected for a simulation case study. The thermal performance potential of the proposed configuration is analyzed and compared to a conventional GT-steam CCPP, a GT- CO2 CCPP without the TIAC and HR system. The results show that the relative power output is enhanced by 14.9% and that the efficiency is improved by 2.1% (1.4%p) compared to the GT- CO2 CCPP without it. Meanwhile, this system enables higher power output and efficiency by 25.4% and 11.5% (6.8%p), respectively, compared to the conventional GT-steam CCPP, and the effect is increased according to the ambient temperature.

Experimental cycle air cooling system for gas microturbine unit

The article considers the Combustion Turbine Inlet Cooling (CTIC) system — an experimental system for cooling the cycle air entering the gas microturbine unit. This enables to save electrical power of the unit generated at the design level in the period of seasonal increase in air temperature. Cooling of the air at the inlet to the turbocharger of the unit occurs up to its design temperature (which is, according to the ISO standard, equal to 15˚С). The basis of the CTIC model is an industrial cooling system based on a vapor compression refrigeration unit with a cold accumulator. Water ice is used as a cold storage medium in the accumulator, while ice water is used as a medium cooling the cycle air (ice water is water at a temperature of 0.5˚С – 1˚С). The eff ect of cooling of cycle air is achieved by pumping ice water coming from the cold accumulator through an air-to-water heat exchanger installed at the inlet to the turbocharger. The purpose of the study was to determine the operating time of a cold accumulator, depending on the speed of the circulating water. The experiments were carried out on a model of a cooling system with a cold accumulator having a 200 kg ice storage and working with the Capstone C-30 microturbine. Maintaining the temperature of the cycle air at its design level is achieved using a frequency-controlled circulation pump and a digital measurement and control system with the LabVIEW software package. The results of the study show that the considered CTIC system, while discharging the cold accumulator, is able to maintain the required design temperature of the cycle air at 15°C for 6 hours, which is quite enough to cover the peak load of the working day. Technical and economic parameters of the plant are evaluated.

Techno-economic Assessment of Turbine Inlet Air Cooling for Cogeneration Plant in Malaysia Climate

The high ambient and humid Malaysia has affected the performance of gas turbine generators. The power augmented from the gas turbine generator can be enhanced by implementing turbine inlet air cooling (TIAC) technologies. In this paper, techno-economic analysis of combined heat and power (CHP) plant using an aero-derivative gas turbine (GE LM6000PD) is presented based on annual performance simulation. There are three cases of comparison that is Non TIAC, TIAC with steam absorption chiller (SAC) and TIAC with electric compression chiller (ECC) is simulated using GT Pro software. The results show that the performance of TIAC with SAC yielding higher annual net electricity output compared Non TIAC and TIAC with ECC but incur highest capital investment and capital outflow. Thus, TIAC with ECC is the best choice for CHP plant due to highest NPV, IRR, fastest PBT and highest net revenue compared to TIAC with SAC and Non TIAC.

Study of Cycling Air-Cooling System with a Cold Accumulator for Micro Gas-Turbine Installations

Using the cycling air-cooling systems of the CTIC type (Combustion Turbine Inlet Cooling) with a cold accumulator in a micro gas-turbine installation (micro-GTI) to preserve its capacity under the seasonal temperature rise of outside air is described. Water ice is used as the body-storage in the accumulators, and ice water (water at 0.5–1.0°C) is used as the body that cools air. The ice water circulates between the accumulator and the air-water heat exchanger. The cold accumulator model with renewable ice resources is considered. The model contains the heat-exchanging tube lattice-evaporator covered with ice. The lattice is cross-flowed with water. The criterion heat exchange equation that describes the process in the cold accumulator under consideration is presented. The calculations of duration of its active operation were performed. The dependence of cold accumulator service life on water circulation rate was evaluated. The adequacy of the design model was confirmed experimentally in the mock-up of the cold accumulator with a refrigerating machine periodically creating a 200 kg ice reserve in the reservoir-storage. The design model makes it possible to determine the weight of ice reserve of the discharged cold accumulator for cooling the cycle air in the operation of a C-30 type micro- GTI produced by the Capstone Company or micro-GTIs of other capacities. Recommendations for increasing the working capacity of cold accumulators of CTIC-systems of a micro-GTI were made.

Performance improvement of gas turbine power plants by utilizing turbine inlet air-cooling (TIAC) technologies in Riyadh, Saudi Arabia

Gas turbine performance is very sensitive to the ambient air conditions, particularly in hot and arid climates. Various turbine inlet air cooling (TIAC) techniques including mechanical vapor compression and lithium bromide-water absorption refrigeration systems are used in several locations worldwide. This work concerns a comparative study using mass and energy balances and cost analysis of several cooling technologies coupled with a typical gas turbine under Riyadh weather conditions. The results are expressed in terms of yearly variations of power output, fuel consumption, and thermal efficiency of the gas turbine unit. They also include the total and operating costs and the payback period for each configuration of TIAC systems. The study proposes first systematic approaches to determine the air cooled temperature at the compressor inlet and the corresponding cooling capacity for the considered TIAC systems. The optimum values of such air cooled temperature and cooling capacity are found to be 8 °C and 36 kW/m3 s−1, respectively. The comparative study shows that using the media evaporative cooling, the simple mechanical vapor compression or the single-effect H2O-NH3 absorption cooling systems are not recommended. However, the sub-cooling multistage compressor system coupled with a wet cooled condenser and the single-effect LiBr-H2O-absorption refrigeration systems show better performance.

Performance Comparison of a Vapor-Adsorption Cycle-Based Gas Turbine Inlet Air Cooling System for Different Refrigerants

Presently, to enhance the thermal efficiency of a gas turbine power plant, turbine inlet air cooling (TIAC) is the widely used technique. The conventional refrigeration methods like vapor compression refrigeration and evaporative cooling need electric power, hence absorption and adsorption refrigeration systems are attractive options as they can be powered using the waste heat energy of the exhaust gases. Adsorption system has advantages over absorption system like scalability, requirement of lower heat source temperature, absence of corrosion and crystallization. This paper focuses on the thermodynamic analysis of waste heat powered adsorption chiller used for the cooling of intake air to enhance the net power output of the gas turbine power plant. This paper also presents a comparative analysis of the vapor-adsorption cycle-based TIAC system for four different refrigerants viz. HFC-134a, carbon dioxide, ethanol and ammonia with the motive of finding a substitute refrigerant for HFC-134a which has a high global warming potential (GWP). The adsorption chiller is mathematically modeled in MATLAB with activated carbon as the adsorbent and each one of carbon dioxide, ethanol and ammonia as the adsorbate. The variation of the coefficient of performance (COP) and specific cooling effect (SCE) with varying adsorption temperatures is presented for each pair. The net power output and primary energy rate (PER) improvement of the gas turbine power plant at different ambient temperatures are also discussed. It is observed that ammonia can improve the power plant performance significantly better compared to the other three refrigerants at ambient temperatures less than 40[Formula: see text]C.