Feedstock Blending Studies With Laboratory Indirectly Heated Gasifiers

1998 ◽  
Author(s):  
Alex E. S. Green ◽  
James P. Mullin
Keyword(s):  
Heat Transfer ◽  
Rate Constants ◽  
Gas Turbines ◽  
Transfer Model ◽  
Data Set ◽  
Measuring Systems ◽  
Volume Yield ◽  
Tube Furnaces ◽  
Further Development ◽  
Temperature Time

To support the further development of indirectly heated gasifiers, intended to provide fuels for advanced gas turbines, several laboratory indirectly heated gasifiers were constructed. During many comparative tests advantages and problems with each system were observed. The most useful systems make use of laboratory tube furnaces in conjunction with temperature, time and pressure or volume yield measuring systems and a gas chromatograph with a thermal conductivity detector. In this paper high temperature pyrolysis results obtained with the latest system are presented. Contrasting feedstocks suitable for commercial systems separately or in blends are used. Yield vs. time measurements are used to determine relevant rate constants and outputs. Since the rate constants are mainly reflective of heat transfer effects, cylindrical dowel sticks of varying radii were volatilized. The data set leads to an analytic heat transfer model that considers the hemicellulose, cellulose, and lignin components of the dowels. Also developed from the dowel experiments is an approximate procedure for estimating the proportionate releases of CO, CO2, CH4 and H2 for any type of biomass whose component proportions are known.

Feedstock Blending Studies With Laboratory Indirectly Heated Gasifiers

1999 ◽  
Vol 121 (4) ◽  
pp. 593-599 ◽  
Author(s):  
A. E. S. Green ◽  
J. P. Mullin
Keyword(s):  
Heat Transfer ◽  
Rate Constants ◽  
Gas Turbines ◽  
Transfer Model ◽  
Data Set ◽  
Measuring Systems ◽  
Volume Yield ◽  
Tube Furnaces ◽  
Further Development ◽  
Temperature Time

To support the further-development of indirectly heated gasifiers intended to provide fuels for advanced gas turbines, several indirectly heated laboratory gasifiers were constructed. During many comparative tests, advantages and problems with each system were observed. The most useful systems make use of laboratory tube furnaces in conjunction with temperature, time, and pressure or volume yield measuring systems and a gas chromatograph with a thermal conductivity detector. In this paper, high temperature pyrolysis results obtained with the latest system are presented. Contrasting feedstocks suitable for commercial systems separately or in blends are used. Yield versus time measurements are used to determine relevant rate constants and outputs. Since the rate constants are mainly reflective of heat transfer effects, cylindrical dowel sticks of varying radii were volatilized. The data set leads to an analytic heat transfer model that considers the hemicellulose, cellulose, and lignin components of the dowels. Also developed from the dowel experiments is an approximate procedure for estimating the proportionate releases of CO, CO2, CH4, and H2 for any type of biomass whose component proportions are known.

Thermal Analysis of a Heat Recovery System for Externally Fired Micro Gas Turbines

2007 ◽  
Author(s):  
Mehdi Bahador ◽  
Takamasa Ito ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Fixed Bed ◽  
Geometrical Parameters ◽  
Transfer Model ◽  
Wood Pellets ◽  
Recovery System ◽  
Material Durability

Several serious problems such as material durability and fouling in the High Temperature Heat Exchanger (HTEH) for Externally Fired Micro Gas Turbines (EFMGT) cause the low thermal efficiency. In this study for increasing the thermal efficiency, a duct around a cylindrical fixed bed combustor which burns wood pellets is proposed and two different designs, empty and porous material filled, are investigated. A heat transfer model, based on coupling between radiative and convective modes at the combustor and duct sides is developed to evaluate the important geometrical parameters in the different designs. The predicted results for the empty duct show that although an increase of the combustion length increases the temperature of air at the duct outlet, an increase of the combustor diameter is more effective. In addition, an increase of the duct cross section is the most effective way and according to the predictions, the pressure drop in this case is still acceptable. The porous duct design shows a significant increase in the air temperature at the duct outlet. However, the pressure drop is high. The investigation shows the possibility of reduction of the pressure drop with the same amount of heat transfer by selecting suitable particle size and porosity.

Gas Turbine Integrated Conceptual Design Approach

2015 ◽  
Author(s):  
Carlo Carcasci ◽  
Stefano Piola ◽  
Roberto Canepa ◽  
Andrea Silingardi
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Conceptual Design ◽  
Gas Turbines ◽  
Power Efficiency ◽  
Heat Transfer Model ◽  
Design Approach ◽  
Transfer Model ◽  
Design Phase ◽  
Conceptual Design Phase

In order to improve performance of heavy-duty gas turbines, in terms of power, efficiency and reliability, accurate calculation tools are required. During conceptual design phase, an effective integration of main GT components design into a single modular simulation tool can significantly reduce design iterations and improve the results. Thanks to an innovative modular-structured program for the simulation of air-cooled gas turbines, the one-dimensional design of compressor and turbine flow paths is used to create a complete gas turbine model including a detailed secondary air system and a simplified heat transfer model. This zero-dimensional heat transfer model is applied to each turbine row in order to calculate the cooling flow required to keep turbine blades and vanes metal temperatures below a prescribed threshold. After a description of the air cooled gas turbine modular model, the integrated design approach adopted by Ansaldo Energia is described. The knowledge of technical risks that the designers have to withstand developing advanced technologies during conceptual engine design is fundamental. The inter-disciplinary influence of some disciplines is analyzed and finally it is shown how Ansaldo Energia approach can track expected performance results and provide recovery plans during the conceptual design phase.

scholarly journals Simulation and Evaluation of Heat Transfer Inside a Diseased Citrus Tree during Heat Treatment

2021 ◽  
Vol 3 (1) ◽  
pp. 19-28
Author(s):  
Shirin Ghatrehsamani ◽  
Yiannis Ampatzidis ◽  
John K. Schueller ◽  
Reza Ehsani
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Experimental Studies ◽  
Canopy Cover ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Heat Penetration ◽  
Simulation Results ◽  
Simulation And Evaluation ◽  
Temperature Time

Heat treatment has been applied in previous studies to treat diseased plants and trees affected by heat-sensitive pathogens. Huanglongbing (HLB) is a heat-sensitive pathogen and the optimal temperature–time for treating HLB-affected citrus trees was estimated to be 54 °C for 60 to 120 s from indoor experimental studies. However, utilizing this method in orchards is difficult due to technical difficulties to effectively apply heat. Recently, a mobile thermotherapy system (MTS) was developed to in-field treat HLB-affected trees. This mobile device includes a canopy cover that covers the diseased tree and a system to supply steam under the cover to treat the tree. It was proven that the temperature inside the canopy cover can reach the desired one (i.e., 54 °C) to kill bacteria. However, for HLB, the heat should penetrate the tree’s phloem where the bacteria live. Therefore, measuring the heat penetration inside the tree is very critical to evaluate the performance of the MTS. In this study, a heat transfer model was developed to simulate the heat penetration inside the tree and predict the temperature in the phloem of the diseased tree during the in-field heat treatment. The simulation results were compared with in-field experimental measurements. The heat transfer model was developed by a comparative analysis of the experimental data using the ANSYS software. Results showed that the temperature in the phloem was 10–40% lower than the temperature near the surface of the bark. Simulation results were consistent with experimental results, with an average relative error of less than 5%.

Carbon Foam: New Generation of Enhanced Surface Compact Recuperators for Gas Turbines

2005 ◽  
Author(s):  
Q. Yu ◽  
B. E. Thompson ◽  
A. G. Straatman
Keyword(s):  
Heat Transfer ◽  
Porous Carbon ◽  
Gas Turbines ◽  
Solid Phase ◽  
Geometric Model ◽  
Carbon Foam ◽  
Unit Cube ◽  
Hydrodynamic Resistance ◽  
Thermal Engineering ◽  
Transfer Model

The potential of porous carbon foam is explored in the context of compact recuperators for microturbine applications. Porous carbon foam has an open, interconnected pore structure and an extremely high solid-phase conductivity, which render the material a viable alternative in compact heat exchanger design. The material is also mechanically stable, non-corrosive and relatively inert to temperatures up to approximately 500°C, which make it particularly attractive for high-temperature non-oxydizing and moderate temperature oxidizing applications. Hydrodynamic and thermal engineering models are proposed based on recent work applied to air-water heat exchangers. The models are developed based on a unit-cube geometric model for carbon foam, a heat transfer model and well-established convective correlations that are extended to account for the effects of the carbon foam. The present calculations suggest that the use of carbon foam in a relatively simple configuration results in a significant reduction in thermal resistance accompanied by a rise in the hydrodynamic resistance. These preliminary results suggest that very compact heat transfer devices could be developed. With further investigation it is felt that the hydrodynamic resistance could be reduced while preserving the heat transfer performance resulting in very high-performance, compact heat transfer devices.

The Influence of Humidity on the Creep Life of a High Pressure Gas Turbine Blade: Part I—Heat Transfer Model

2012 ◽  
Author(s):  
S. Eshati ◽  
P. Laskaridis ◽  
A. Haslam ◽  
P. Pilidis
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Gas Flow ◽  
Thermal Barrier ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Creep Life ◽  
Gas Properties

The cooling of high temperature gas turbines has been the subject of intensive work over the past few decades. Analysis of the metal temperature of cooled blades requires the solution of the equations governing the heat flow through the blade given the internal and external distributions of the boundary gas temperatures and heat transfer coefficients. An analytical model to investigate the influence of Water Air Ratio (WAR) on turbine blade heat transfer and cooling processes (and thus the blade creep life) of industrial gas turbines is presented. The method is based on a blade with convective cooling and a thermal barrier coating (TBC). The approach is based on engine performance, heat transfer models (hot side and cold side model), in addition to a method that accounts for the changes in thermal conductivity, viscosity, density and the gas properties of moist air as a function of WAR. The evaluation of heat transfer data in this model is considered by using non-dimensional parameters namely: Reynolds number, Nusselt number, Stanton number, Prandtl number and other related parameters. The aim of this paper is to present an analytical model to investigate the influence of humidity on the turbine blade heat transfer and cooling processes which, in turn, affect blade creep life. The developed model can be used to assess the main parameters that influence blade cooling performance, such as cooling methods, alternative cooling fluids, blade geometry, gas properties and material and thermal barrier coatings. For a given off-design point, the WAR was varied from dry to humid air (air/water vapour mixtures). The whole cooled blade row is regarded as a heat exchanger with the presence of TBC subjected to a mainstream hot gas flow from the combustion chamber.

Numerical simulation of subduction zone pressure-temperature-time paths: constraints on fluid production and arc magmatism

1991 ◽  
Vol 335 (1638) ◽  
pp. 341-353 ◽  
Keyword(s):  
Heat Transfer ◽  
Partial Melting ◽  
Subduction Zone ◽  
Subduction Zones ◽  
Mantle Wedge ◽  
Thermal Structure ◽  
Oceanic Lithosphere ◽  
Transfer Model ◽  
Temperature Time ◽  
Subducting Slab

The location and sequence of metamorphic devolatilization and partial melting reactions in subduction zones may be constrained by integrating fluid and rock pressure-temperature-time ( P-T-t ) paths predicted by numerical heat-transfer models with phase diagrams constructed for metasedimentary, metabasaltic, and ultramafic bulk compositions. Numerical experiments conducted using a two-dimensional heat transfer model demonstrate that the primary controls on subduction zone P-T-t paths are: (1) the initial thermal structure; (2) the amount of previously subducted lithosphere; (3) the location of the rock in the subduction zone; and (4) the vigour of mantle wedge convection induced by the subducting slab. Typical vertical fluid fluxes out of the subducting slab range from less than 0.1 to 1 (kg fluid) m -2 a -1 for a convergence rate of 3 cm a -1 . Partial melting of the subducting, amphibole-bearing oceanic crust is predicted to only occur during the early stages of subduction initiated in young (less than 50 Ma) oceanic lithosphere. In contrast, partial melting of the overlying mantle wedge occurs in many subduction zone experiments as a result of the infiltration of fluids derived from slab devolatilization reactions. Partial melting in the mantle wedge may occur by a twostage process in which amphibole is first formed by H 2 O infiltration and subsequently destroyed as the rock is dragged downward across the fluid-absent ‘hornblende-out’ partial melting reaction.

Methodology to Evaluate Turbocharger Turbine Performance at High Blade to Jet Speed Ratio Under Quasi Adiabatic Conditions

2017 ◽  
Author(s):  
José Ramón Serrano ◽  
Luis Miguel García-Cuevas ◽  
Lukas Benjamin Inhestern ◽  
Holger Mai ◽  
Andrea Rinaldi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Internal Combustion Engines ◽  
Low Flow ◽  
Speed Ratio ◽  
Transfer Model ◽  
Data Set ◽  
Compressor Wheel ◽  
Adiabatic Conditions ◽  
Turbine Performance ◽  
The Impact

Current key technologies to meet the future emission standards for internal combustion engines are downsizing, down-speeding, and advanced charging concepts. While turbocharging already combines high specific rated engine power with low fuel consumption, there is still potential for optimization to achieve prospective demands for fuel efficiency with low emissions. Using engine exhaust energy, the turbine underlies pulsating flow conditions from high towards zero mass flow at almost constant blade speed. The average turbine efficiency is then affected for the high blade to jet speed ratio conditions, which is very important at low engine loads during urban driving conditions. Since turbocharger performance is very sensitive for the overall engine efficiency, a very accurate measurement of the characteristic maps is desired to evaluate the thermodynamic behavior of the turbocharger and to ensure best possible matching. This paper presents a methodology to extend the turbine performance at low expansion ratio and to characterize the adiabatic efficiency in a wide operating range. This enables measuring turbines on a hot-gas test bench at very high blade to jet speed ratio and very low turbine flow to develop, improve, and validate reliable turbocharger models that can be used for full engine simulations. The industrial applicability has been proven from very low turbine power up to negative turbine power output simply based on using inlet guide vanes (IGV) upstream of the compressor. By generating a swirl in the compressor wheel rotating direction and pressurizing the inlet air, the compressor can be run as a turbine. Thus, the compressor provides power to the shaft and the turbine can be driven with very low flow power. The test campaign has been realized under quasi-adiabatic conditions to limit the heat transfer. While measuring at three different oil temperatures, the impact of remaining internal heat transfer has been taken into account. A turbocharger heat transfer model has also been used to correct residual heat flows from the obtained data set for all oil temperatures.

Cooled Pressure Probes Design Methodology for Harsh Environment Applications

2020 ◽  
Author(s):  
Julien Clinckemaillie ◽  
Fabrizio Fontaneto
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Conjugate Heat Transfer ◽  
Fast Response ◽  
Pressure Probe ◽  
Transfer Model ◽  
Mass Flow Rates ◽  
Response Pressure ◽  
Final Extent ◽  
Probe Geometry

Abstract The present paper discusses in detail the methodology adopted for the cooling layout design of a water-cooled fast-response wall-static pressure probe intended for measurements in the combustion chamber of gas turbines. The proposed design approach is structured upon three main steps. In the first step, different reduced order correlations for convective and radiative heat transfer are used to derive the heat load at which the measurement device is submitted. In the second part, a quasi-2D conjugate heat transfer model is developed and operated through the application of the boundary conditions computed in the previous step. The model is based on empirical correlations and computes representative global cooling performance parameters for different cooling layouts and coolant mass flow rates. In the final step, the obtained design candidate is further validated by means of state-of-the-art fully 3D conjugate heat transfer numerical simulations performed on a probe geometry characterized by an increased degree of complexity. At its final extent, the present paper describes and validates a complete and robust methodology for the design of a cooling layout for cooled fast-response pressure probes.

Effect of Surface Roughness Induced by Laser Powder Bed Fusion Additive Manufacturing in a Mini-Channel Heat Exchanger

2019 ◽  
Author(s):  
T. Parent-Simard ◽  
A. Landry-Blais ◽  
P. K. Dubois ◽  
M. Picard ◽  
V. Brailovski
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Exchanger ◽  
Gas Turbines ◽  
Low Cost ◽  
High Surface ◽  
Transfer Model ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

Abstract The Inside-Out Ceramic Turbine (ICT) is a promising microturbine for aeronautics applications. To increase the cycle efficiency and reduce fuel consumption, microturbines must operate under the recuperated Brayton cycle. The addition of a heat exchanger (HEx) increases the weight of the engine and cancels out any fuel savings as compared to a non-recuperated turbine. For this reason, the requirements applied to HEx for aeronautic gas turbines are: low weight and volume, high effectiveness with a low pressure drop, capabilities to endure high pressure and temperature, and low cost. The Laser powder bed fusion (LPBF) opens a new design space for geometries that cannot be realized by conventional methods, but induces high surface roughness. This paper presents experimental and analytical studies of the influence of surface roughness on the performances of a 3D-printed, counterflow, mini-channel HEx, with 1% of the total mass flow rate of the ICT. Results showed that the friction and heat transfer are both increased in the the regime typically defined as laminar compared to the analytical results. The experimental results are in agreement with a 1D heat transfer model when using correlations for high-roughness values from the literature. LPBF is a promising method to manufacture gas turbine parts, but it is crucial to model and incorporate its manufacturing capacities in terms of precision and surface finish to enhance HEx heat transfer and potentially reduce mass.

Sign in / Sign up

Export Citation Format

Share Document