Cooling Air Flow Rate Research Articles

Measurement of gas turbine cooling air flow rate at an advanced combined cycle power plant using the heater method for plant operation and maintenance

Measurement of gas turbine cooling air flow rate at an advanced combined cycle power plant using the heater method for plant operation and maintenance

Determining required turbine cooling air flow rate at the conceptual design stage of gas turbine engine

Determining required turbine cooling air flow rate at the conceptual design stage of gas turbine engine

Measurement of Cooling Air Flow Rate in a Large Gas Turbine using the Heater Method

Measurement of Cooling Air Flow Rate in a Large Gas Turbine using the Heater Method

Experimental Evaluation of Using Silica Aerogels as the Thermal Insulator for Combustor Liners

An experimental study was conducted for evaluating the feasibility of using silica aerogel as thermal insulator for combustor liners. Aerogels are a superior material for minimizing heat flux to the metal structure of the combustion liner due to their low thermal conductivity. In this study, a conical natural gas fired swirling-flame combustor was utilized for reproducing the combustion environment. The silica aerogel blanket was attached to the inner side of a perforated combustor liner. Temperature distribution on the outer side of the combustion liner was measured using a calibrated IR camera. To create a protective cooling film over the aerogel surface, cooling air was supplied from the back side of the perforated metal liner and was allowed to penetrate the silica aerogel blanket to be discharged to the combustor. As the combustor was operated at a fixed equivalence ratio of 0.83, cooling air flow rates were varied to evaluate the effectiveness of transpiration cooling on the aerogel blanket as various cooling flow rates. The measured evolution of temperature distribution confirmed thermal equilibriums for every test condition with transpiration cooling. The measured temperature distribution of metal liner demonstrated superior thermal insulation of aerogel blanket under the protection of cooling film with a temperature difference as high as 1580 K between combustion products temperature and the metal liner temperature on the back side. In addition, silica aerogel samples were examined before and after the combustion tests to understand their material degradation exposing to a typical gas turbine combustor environment using high-resolution scanning electron microscope (SEM). Test results suggest multiple degradation mechanisms to the silica aerogel blanket samples from the combustion tests. Improvements can be made to the silica aerogel blankets for a more resilient thermal insulator, for example, by replacing glass fibers in silica aerogels.

Temperature calculation for linear induction motor in transport application with multiphysics approach

The article describes the implementation of the mathematical model of the interrelated electromechanical and thermal processes in a linear induction motor using simulation software MATLAB-Simulink. The developed model consists of electromechanical model, thermal model and cooling system (hydraulic) model which all affect each other. Temperature calculations of the traction single-sided linear induction motor for urban transportation system are performed for different regimes. The calculation results using the developed thermal model based on the thermal detailed equivalent circuit demonstrate a close concurrence with the finite element model, temperature values differ less than in 3.8-4.8%. Safe operation range for a traction linear induction motor was determined taking into account the uneven longitudinal heating using different variants of cooling systems and coolant flow values. Recommendations on their selection were formulated. Based on the calculations and following experimental testing it was determined that operation with the maximum load with current of 270 A and load force of 8,000 N is possible with the cooling air flow rate of at least 2.2 m3/s.

Analyzing regularity of interpolar air motion and heat dissipation coefficient distribution of a salient pole synchronous generator considering rotary airflow

The extreme attention should be paid to cooling performance of air-cooled synchronous generators in order to ensure that the temperature rise of each part is within the allowable range. It is necessary to know losses distribution, cooling airflow rate distribution laws, heat dissipation coefficient distribution and temperature distribution characteristics. Considering the influence of rotary airflow and yoke ventilation duct structure on air motion, the physical parameters and the motion characteristics of interpolar air were analyzed in three cases. These cases were considered respectively when the rotor was in a rotating or non- rotating state and the yoke ventilation ducts were intake air, and when the rotor was in a rotating state and the yoke ventilation ducts were not intake air. Based on Multi-Reference Frame, the finite volume method was used to solve the fluid-solid coupling numerical simulation of the solving domain. Taking a 250 MW air-cooled hydro-generator as an example, the air velocity of each air cooler was measured and the inlet air velocity of the rotor support was calculated. By calculating the average temperature of the excitation winding in the steady state, the measured value and the simulation result were compared, and the correctness of the calculation method was verified.

Improvement of Thermal Performance using Spineloxides/Water Nanofluids in the Heat Recovery Unit with Air-to-Air Thermosiphone Mechanism

Heat recovery units are used for pre-heating the fresh air in waste heat plants. The nanofluid used as working fluid in the heat pipe will allow the heat recovery unit to benefit from the waste heat at lower temperatures, since it can evaporate at a temperature lower than the temperature of the base fluid. Therefore, the range of the operating temperature of the heat recovery unit will be increased. Different temperatures and flow rates of waste heat were used to find the optimum conditions for the evaporation of spinel nanofluid in the evaporator region of the heat pipe. Similar conditions were investigated for both of the cold fluid and optimal conditions on the condensation of nanofluid in the condenser region. In this study, an experimental setup was designed to improve the thermal performance of the air-to-air containing heat pipe heat recovery unit. The experiments were carried out using pure water-based nanofluids containing nano-sized ZnOAl2O3, MgOAl2O3, FeOAl2O3 particles, and the efficiencies of the heat transfer were investigated in this experiment. A thermosiphon mechanism that consists of five heat pipes, the length of each one is equal to 1 m, and the inner and the outer diameter of them is equal to 23.4 mm and 25.4 mm, respectively, those pipes are vacuumed, without wick and copper material. Heat pipes in the experimental setup; the evaporation zone is positioned to form 450 mm, the condensation zone 400 mm and the middle 150 mm parts to form the adiabatic region. At the beginning of the experiments, the working fluid charged to fill the 1/3 of the evaporation zone volumes of the heat pipes. Two different cooling air flow rates, 30 g·s−1 and 60 g·s−1, and three different heating air flow rates, 50 g·s−1, 70 g·s−1, 90 g·s−1 have been used, to calculate the heat obtained from the condensation zone. All the experiments were carried out by applying two different heaters with a power of, 1000 W and 2000 W, in the evaporation zone. Thus, the optimum temperatures and flow rates were found for all Reynolds numbers in the hot and cold fluid region, and its helps to determining the ranges of the operating temperature in the heat recovery unit. The experimental results that obtained from the two different working fluids (pure water and nanofluid) are compared. The best thermal performance of the system was found in the hot and cold air duct, when the Reynolds number was equal to 12 000. The thermal performance improvement rate was found as 92.8 % when the FeOAl2O3/water nanofluid used as working fluid, and 1000 W heater power and 60 g·s−1 cooling air flow applied.

Analysis and comparison of potential power and thermal management systems for high-speed aircraft with an optimization method

• An advanced PTMS with an indirect regenerative air cycle is analyzed. • A comparison based on minimum fuel weight penalty optimization is proposed. • Optimal matching of the PTMS and flight mission is achieved at Mach 1-4.4. • The PTMS with a ram air bleed mode is suitable for Mach 3.4–4.4 cruise aircraft. Under the dual effects of aerodynamic heating and high-power electronic equipment heating, the heat sink and power demand of advanced high-speed aircraft have been exponentially rising, which seriously restricts the aircraft performance. To improve system cooling and power supply performance and reduce engine performance loss, a power and thermal management system (PTMS) with high performance, low energy consumption, and light weight urgently needs to be developed. In this paper, three modes of a potential PTMS with different heat sinks and bleed air sources are further discussed to analyze and compare the optimal matching with the flight mission at Mach 1–4.4. The equivalent mass method is used to uniformly assess the costs of the fixed weight, bleed, resistance, etc. as a function of the fuel weight penalty, which is chosen as the optimization objective. The optimization variables consist of the compressor outlet temperature, cooling air flow rate, and fan duct heat exchanger structure size. The results show that the intermediate-stage bleed air and fan duct heat sink are more suitable when the Mach number is less than 2, but the ram air bleed is highly suitable for flight missions at a high Mach number. Especially at Mach 3.4–4.4, the ram air bleed mode can respond to the cooling and power demands with a simple architecture.

An Experimental and Theoretical Study of Forced Convection from a Peltier Thermo-electric Cooling

An experimental and theoretical study for heat transfer through thermoelectric cooling system in this paper was presented. An experimental work was conducted to evaluate the performance of a thermoelectric module fitted to a sun flower heat sink with a similar sized heat source. The experimental investigation was done to evaluate the effect of TE input voltage, flow rates of cooling air and heat source (heating element) power input on the performance of a thermoelectric cooling system. Four low heating load (1.7, 2.4, 3.6 and 5 W) were used and hot side was fitted to a sunflower heat sink with forced convection. Experimental results show that the increasing of cooling air flow rates improves system performance, while increasing in applied TE voltage leads to deterioration it. The COPmax obtained is about 4.7 at 2V TE voltages and 5W heating load, and then decreased sharply as voltage further increased and reaches 0.13 at 12V. The results of the current study show that all Thermo-electric Cooling system recorded temperatures increase with increasing in heating load at a constant TE voltage and air flow rate. In addition to that the Tc decreases and Th increases with the increment of input voltage and that can lead to increase of the air temperature passing over heat sink. TE performance is highly affected by air flow rate. The theoretical result validated experimentally and shows an acceptable agreement between them.

Investigating the possibility of increasing cooling air flow in a hydrogenerator rotor fan

The possibility of increasing cooling airflow inside a hydrogenerator rotor fan is investigated. The rotor fan has a heat dissipation problem and it is suggested to investigate the increase of cooling airflow by fan redesign. The cooling airflow passes through many air ducts in the rotor and stator cores. To reduce the computational efforts, these ducts are simulated as porous media. The computational domain is discretized by hexahedral structured mesh. The rotating reference frame is used for rotating boundaries. Continuity and momentum equations are solved and the realized k–e turbulence model is applied. Results show that a big vortex is produced at the inlet of rotor fan which causes energy dissipation. Therefore, a new impeller is introduced at the rotor fan entrance to correct the inlet airflow. Results indicate that improving the rotor fan geometry can increase the cooling airflow rate by 19%.

Investigation into Operating Conditions of a Dry Mechanical Draft Cooling Tower at the TETs-12 Cogeneration Power Station of PAO Mosenergo

The results of the comprehensive investigation into operation of a dry mechanical draft cooling tower (DMDCT) of a PGU-220 power unit at the TETs-12 cogeneration power station of PAO Mosenergo are presented. Thermal performance of the main and auxiliary DMDCTs and their individual sections is examined. To determine the cooling-air flowrate, a rake consisting of 11 velocity transducers and thermocouples was installed at the fan outlet above the fan diffuser of the examined section. The DMDCT heat balances calculated on the basis of water- and cooling-air conditions agree with each other with a maximum error of 8%. The overall thermal performance indices of the main and auxiliary DMDCTs were lower than those specified by the supplier. Performance of DMDCT fans was investigated at different blade angles α. According to our calculations, the effect of better fan performance in terms of an increase in the power of a steam turbine in a combined-cycle unit at α > 15° does not compensate for an increase in the power consumption of fan motors and even reduces the amount of delivered power. Therefore, the range of α = 10°–15° for the fans of the main DMDCT may be considered optimal. As to the auxiliary cooling tower, an increase in the air flow at α = 17° can offer a wider operation range for the fans at high ambient air temperatures, which is important considering limitations on the supply temperature (below 35°С) of the auxiliary equipment cooling water. The investigation of DMDCT operation during the cold season yielded the dependence of the minimum heat load of DMDCT, required for its safe operation, on the ambient air temperature. The study into the performance of the humidification system revealed that its efficiency is inadequate. The best solution to this problem is to replace the normal humidification nozzles with nozzles with smaller diameter holes to improve water dispersion that will prevent the water drops from falling onto the ground and improve the efficiency of the humidification system while decreasing the water flow to the humidification nozzles.

Modeling of Room Temperature Dynamics for Efficient Building Energy Management

Heating, ventilating and air-conditioning systems have a significant share in the energy consumed by buildings. Modeling of room temperature dynamics is the first-step in designing an efficient air-conditioning system. In this regard, this paper proposes a semi-nonlinear thermal model: ordinary differential equation, with parameters as nonlinear functions of ambient temperature and cooling air flow-rate. To validate the performance of the model, a three-roomed building, equipped with an air-conditioning system is modeled, and Navier–Stokes equations are solved to simulate the temporal evolution of temperatures for different ambient temperatures and cooling air flow-rates. The steady-state temperature and transient solution parameters of the thermal model are assumed to be polynomial functions of ambient temperature and flow-rate, and are determined by minimizing the errors between the thermal model- and the computational fluid dynamics-based solutions of final and transient temperatures, respectively. The proposed thermal model of third-order and nonlinear type transient coefficients is shown to predict the temporal evolution of temperature accurately. Further increase in prediction accuracy is achieved by recursively updating the parameters online using extended Kalman filter. The high prediction accuracy of the proposed thermal model makes it a potential candidate for the design of an optimal temperature regulator.

Parameter study of sinter waste heat recovery in vertical tank based on energy and exergy analysis

The parameter study of sinter waste heat recovery in vertical tank was conducted numerically by using energy and exergy analysis, and the experimental data obtained from a homemade experimental apparatus was applied to verify the reliability of numerical model. Based on the first and second laws of thermodynamics, the effects of flow rate of cooling air (FRCA) and inlet temperature of cooling air (ITCA), as well as the inner diameter of cooling section (IDCS) and height of cooling section (HCS), on the sinter cooling process were analyzed in detail. The results show that the average deviation between the experimental data and calculation values is 4.93%, and the model reliability is verified. The enthalpy exergy of outlet air tends to increase first and then decrease with increasing the FRCA and ITCA, while increasing the IDCS only leads to the increase in enthalpy exergy of outlet air. For a given operational condition, the enthalpy exergy of outlet air can reach a maximum value with increasing the HCS. The vertical tank could obtain the maximum enthalpy exergy of outlet air through the adjustments of FRCA and ITCA, as well as the HCS.

The Research of the Thermal State of the Umbrella Type Hydrogenerator by САЕ Methods

In submitted paper the research of the thermal state of the umbrella type Hydrogenerator rated 60 MW is considered. Heating and ventilation calculation was performed in a three-dimensional formulation using the Solid Works Flow Simulation. The possibility of determining of the boundary conditions of the 3-rd kind necessary for determining of the thermal-stressed state of and units of Hydrogenerators emerging in their constructive and active parts is shown. The criterion for the convergence of the proposed method was to determine the minimum allowable losses to ventilation while ensuring the required cooling air flow rate necessary for the Hydrogenerator cooling. At that, the temperature fields of the active parts of the generator are maintained uniform. The design feature of the ventilation system is specially profiled forced elements in the form of plates fastened on the rotor rim. The temperature of the active parts did not exceed the limit of acceptable values according to GOST 5615-89 for insulation class F .

Analyzing the Possibility of Reducing Power Loss in a Cooled Power-Generating Gas Turbine Unit

Evolutionary development of power-generating gas turbine units (GTUs) is characterized by an increase of their parameters and the compressor output and improvement of turbine machinery aerodynamics. With the initial gas temperature increased to 1600°С, the flowrate of compressor air taken for cooling the turbine increases, and its value in the most powerful single-shaft GTUs operating according to a simple thermodynamic cycle reaches 20% of the compressor output. Admixture of air to hot gases causes them to become cooler, which entails heat loss proportional to the total cooling air flowrate. The extent to which the cooling air flowrate is reduced has an essential effect on the improvement of the GTU and combined-cycle power plant (CCPP) efficiencies. The article discusses the possibilities of reducing the cooling air flowrate due to applying closed-loop cooling of the turbine initial stages and using the heat removed in the power generating cycle. In the case of using well-known steam cooling, the removed heat is used in the CCPP steam part, and it is used in the gas turbine cycle with water cooling. In the latter case, the removed heat can be returned into the cycle by using advanced, single-loop water cooling of nozzle vanes and rotor blades. The effectiveness of using closed-loop cooling is evaluated for two values of initial gas temperature of 1430 and 1600°С. With the initial gas temperature of 1430°С, compressor pressure ratio of 23, compressor output of 675 kg/s, and heat removal rate of 21.1 MJ/s, the efficiency of a GTU equipped with water cooling of only its first stage (41.3%) is higher than it is with the initial fully air cooling (39.5%) and existing steam cooling (40.5%) of two stages. The efficiency values of a CCPP with water-cooled and steam-cooled GTUs become essentially equal to each other (60%) and are by 2% higher than the efficiency of an air-cooled CCPP (58%). With the initial gas temperature of 1600°С and the first stage equipped with water cooling, the air flowrate extracted for cooling decreases down to 10%, the GTU efficiency increases to 44.7%, and the CCPP efficiency makes 65.2%, which is 2.1% (abs.) higher than the efficiency of a CCPP equipped with a modern fully air cooled GTU.

Impact of Server Thermal Design on the Cooling Efficiency: Chassis Design

There are various designs for segregating hot and cold air in data centers such as cold aisle containment (CAC), hot aisle containment (HAC), and chimney exhaust rack. These containment systems have different characteristics and impose various conditions on the information technology equipment (ITE). One common issue in HAC systems is a pressure build-up inside the HAC (known as backpressure). Backpressure also can be present in CAC systems in case of airflow imbalances. Hot air recirculation, limited cooling airflow rate in servers, and reversed flow through ITE with weaker fan systems (e.g., network switches) are some known consequences of backpressure. Currently, there is a lack of experimental data on the interdependency between overall performance of ITE and its internal design when backpressure is imposed on ITE. In this paper, three commercial 2-rack unit (RU) servers with different internal designs from various generations and performance levels are tested and analyzed under various environmental conditions. Smoke tests and thermal imaging are implemented to study the airflow patterns inside the tested equipment. In addition, the impact of hot air leakage into the servers through chassis perforations on the fan speed and the power consumption of the servers are studied. Furthermore, the cause of the discrepancy between measured inlet temperatures by the intelligent platform management interface (IPMI) and external sensors is investigated. It is found that arrangement of fans, segregation of space upstream and downstream of fans, leakage paths, the location of baseboard management controller (BMC) sensors, and the presence of backpressure can have a significant impact on ITE power and cooling efficiency.

A proton exchange membrane fuel cell with an airflow cooling system: Dynamics, validation and nonlinear control

This work synthesizes a reduced-order sliding mode observer-based sliding mode controller for a proton exchange membrane fuel cell system. This multivariable closed-loop system is dealt with two inputs (hydrogen fuel flow and cooling air flow rate) and two outputs (output voltage and stack temperature). For this, at first, we develop a nonlinear transient proton exchange membrane fuel cell model. This model is verified with the available experimental data. To maintain the fuel cell operating temperature, it is coupled with an airflow cooling fan. Then a nonlinear model-based control scheme is formulated that consists of sliding mode controller and reduced-order sliding mode observer. A special care is taken in control model against chattering response. Evaluating the sliding mode observer performance, it is integrated with sliding mode controller and the resulting hybrid control structure is compared with a traditional proportional integral controller. The nonlinear sliding mode observer-based controller shows its superiority over the proportional integral controller in rejecting the disturbance as well as tracking the set point.

Effect of Environmental Wind on Performance of a 600MW Direct Air-cooled Unit Based on FLUENT

The external flow field of a 600MW air-cooled unit is numerically simulated based on FLUENT. The distribution law of air flow field of air-cooled unit under different wind speed and wind direction conditions is studied. The influence of wind speed and wind direction on the heat transfer performance of air-cooled unit is analyzed. Predict the exhaust pressure of direct air-cooled unit under the influence of environmental wind. The results show that in the +X direction environmental wind, the first row of air-cooled unit on the windward side is prone to backflow; in the +Y direction environmental wind, the first row of air-cooled unit on the windward side is prone to hot air recirculation. As the wind speed increases, the heat transfer efficiency of the air-cooled unit decreases. The dominant wind direction (WNW) environmental wind has the least impact on the heat transfer efficiency, and the furnace wind (+Y direction wind) has the greatest influence on the heat transfer efficiency. To improve the heat transfer performance of the air-cooled unit under windy conditions, it is necessary to narrow the range of the negative pressure zone below the air-cooled unit and increase the cooling air flow rate of the air-cooled unit.

Experimental investigation of volumetric exergy transfer coefficient in vertical moving bed for sinter waste heat recovery

The volumetric exergy transfer coefficient of sinter bed layers in vertical tank for sinter waste heat recovery has been presented. Correlations involving relevant variables to predict the local and mean volumetric exergy transfer coefficient, Nusselt number and the non-dimensional exergy flux have been deduced by using the second law of thermodynamics and non-equilibrium thermodynamics theory. The relationships of the local and mean volumetric exergy Nusselt number with the local and mean volumetric heat transfer Nusselt number and Reynolds number are analyzed. The experimental results of exergy transfer characteristics in sinter moving bed with different cooling air flow rate and different sinter mass flow rate are obtained from a homemade moving bed set up, and the influences of the height of gas-solid heat exchange section, Reynolds number and gas-solid water equivalent ratio on exergy transfer characteristics are graphically and analyzed. The research results indicates that air-sinter exergy transfer process is mainly determined by the exergy transfer caused by temperature difference, and the impact of exergy transfer due to internal pressure loss is relatively small for given vertical tank and sinter particles. There is an ideal range of gas-solid water equivalent ratio, which makes exergy transfer more efficient.

Variable refrigerant flow cooling assessment in humid environment using different refrigerants

Variable Refrigerant Flow (VRF) is a cooling system developed to anticipate and minimize operating and maintenance costs. VRF allows personalized control and maximizes flexibility to accommodate changing tenants in high rise and compound buildings in hot and humid environments. Although many studies have previously modeled VRF systems from an energy perspective, minor attempts have been made to analyze the exergy performance of this technology. The aim of this paper is to present an exergy/energy analysis of VRF technology to address the effect of refrigerant flow as well as the cooling-air flow rates on the electric energy saving in the hot and humid zones. This analysis will be then used to investigate its performance in humid areas, particularly the Gulf region. VRF is an advanced air conditioning system that is developed to manage load variability by controlling the compressor speed and the expansion valve opening. It is proposed that the system be implemented at Masdar City buildings, located in Abu Dhabi.In this study, VRF units from different manufacturers were modeled and compared using engineering equation solver (EES) and IPSEpro software. The models, which were mainly developed on EES were repeated for validation on similar models that have been developed using the IPSEpro software, and the results were in agreement within 6% uncertainty. Parametric studies were done after modeling the system on EES, where both the high and low pressures in the cycle were varied to obtain the corresponding COP and second law efficiency operating range. It was noticeable that COP and second law efficiency are significantly affected by the evaporator and condenser temperatures and pressures. In addition, as significant concern has been raised due to the impact of refrigerants on global warming, different refrigerants were considered and the results showed that refrigerant R-410a would be the second most efficient refrigerant, after ammonia, for such systems. Finally, an effectiveness NTU evaporator model was implemented to minimize the overall power consumption of the VRF system under various zone loads. It was found that, under a typical set of zone loads, the optimal refrigerant evaporating temperature is 11 °C, when the sum of indoor fan power and outdoor unit power is minimized using the exergy balance. These results helped decision makers to install the VRF system for the first time in that hot and humid area. The preliminary results for May and June sowed an average energy saving of 32% with variable evaporators and condenser speed and variable compressor frequency.