Computational Fluid Dynamic Analyses of Flow and Combustion in a Domestic Liquefied Petroleum Gas Cookstove Burner—Part II: Burning Characteristics and Overall Performance

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Mithun Das ◽  
Ranjan Ganguly ◽  
Amitava Datta ◽  
Meenam M. Verma ◽  
Ashis K. Bera
Keyword(s):  
Heat Flux ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Equivalence Ratio ◽  
Vessel Diameter ◽  
High Energy ◽  
Liquefied Petroleum Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Load Height

Abstract Liquefied petroleum gas (LPG) is widely used in domestic cookstoves as it is a clean and high energy content fuel in comparison with other traditional cooking fuels. With the increasing demand of LPG, study and improvement of cookstove performance have become an important subject. In the present work, a numerical study of the flow and thermal fields for a domestic cookstove burner has been investigated and the performance of the stove is analyzed at different parametric conditions, like the equivalence ratio of the primary fuel–air mixture, fuel flow rate, thermal load height, and loading vessel size. The maximum thermal efficiency has been found for an equivalence ratio of 1.4 for the LPG–air mixture and at load height of 20 mm. The heat flux distribution at the bottom of the vessel is found to be bimodal with the higher peak occurring closer to the center of the vessel. The thermal efficiency of the stove increases with the rise in the fuel flow rate, and it decreases with reducing cooking vessel diameter. As the vessel diameter increases, the fraction of the total heat supplied through the vessel bottom increases. The radiative component of the heat flux is found to be much smaller compared to the convective component.

Modified Brayton Cycle for Turbofans

2019 ◽  
Author(s):  
Chirag Singhal ◽  
Sameer Hasan ◽  
M. F. Baig
Keyword(s):  
Flow Rate ◽  
Thermal Efficiency ◽  
Pressure Ratio ◽  
Enthalpy Of Combustion ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Percentage Increase ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Total Thrust

Abstract In the present study, a design point analysis of twin-spool turbofan engines is carried out, considering fuel injection of Aviation Turbine Fuel (ATF) in the initial stages of the compressor instead of combustor The two-phase compression brings about intercooling in the modified Brayton cycle, by injecting the atomized fuel directly in the initial stages of axial-flow compressor. The intercooling effect results in reduction of compressor work while reinforcing the enthalpy of combustion of fuel due to change of state of fuel from liquid to vapor state. This brings about an improvement in the thrust and thermal efficiency of the modified cycle. Effect of the intercooling is investigated for different performance parameters namely Fuel flow rate ṁf Total thrust Fs, Thermal efficiency ηth, Overall efficiency ηo and Modified cycle factor MCF over the varying compressor pressure ratio (CPR). Injecting the fuel in the 2nd stage of compression results in percentage increase of total thrust by 21.14%, MCF by 31.35%, ηo by 14.92% and decrease in Fuel flow rate ṁf by 7%. While injecting the fuel in the 5th stage of compression results in increased ηo by 17.54 %, MCF by 37.30%, total thrust by 5.68% and decrease in Fuel flow rate ṁf by 22% at a CPR = 30 and Turbine Inlet Temperature (TIT) = 1260K vis-à-vis conventional cycle. Injecting the fuel in latter stages of compressor brings about a decrease of total thrust as well as efficiency.

Dynamic Simulation of a HRSG System for a Given Start-Up/Shut Down Curve

2011 ◽  
Author(s):  
Hun Cha ◽  
Yoo Seok Song ◽  
Kyu Jong Kim ◽  
Jung Rae Kim ◽  
Sung Min KIM
Keyword(s):  
Dynamic Analysis ◽  
Gas Turbine ◽  
Flow Rate ◽  
Exhaust Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Start Up ◽  
Gas Turbine Exhaust ◽  
Main Steam ◽  
Duct Burner

An inappropriate design of HRSG (Heat Recovery Steam Generator) may lead to mechanical problems including the fatigue failure caused by rapid load change such as operating trip, start-up or shut down. The performance of HRSG with dynamic analysis should be investigated in case of start-up or shutdown. In this study, dynamic analysis for the HRSG system was carried out by commercial software. The HRSG system was modeled with HP, IP, LP evaporator, duct burner, superheater, reheater and economizer. The main variables for the analysis were the temperature and mass flow rate from gas turbine and fuel flow rate of duct burner for given start-up (cold/warm/hot) and shutdown curve. The results showed that the exhaust gas condition of gas turbine and fuel flow rate of duct burner were main factors controlling the performance of HRSG such as flow rate and temperature of main steam from final superheater and pressure of HP drum. The time delay at the change of steam temperature between gas turbine exhaust gas and HP steam was within 2 minutes at any analysis cases.

Model Analysis of Syngas Combustion and Emissions for a Micro Gas Turbine

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Chi-Rong Liu ◽  
Hsin-Yi Shih
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Heat Input ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Fuel Flow Rate ◽  
Micro Gas Turbine ◽  
Fuel Flow ◽  
Temperature Distributions ◽  
Flame Structures

The purpose of this study is to investigate the combustion and emission characteristics of syngas fuels applied in a micro gas turbine, which is originally designed for a natural gas fired engine. The computation results were conducted by a numerical model, which consists of the three-dimension compressible k–ε model for turbulent flow and PPDF (presumed probability density function) model for combustion process. As the syngas is substituted for methane, the fuel flow rate and the total heat input to the combustor from the methane/syngas blended fuels are varied with syngas compositions and syngas substitution percentages. The computed results presented the syngas substitution effects on the combustion and emission characteristics at different syngas percentages (up to 90%) for three typical syngas compositions and the conditions where syngas applied at fixed fuel flow rate and at fixed heat input were examined. Results showed the flame structures varied with different syngas substitution percentages. The high temperature regions were dense and concentrated on the core of the primary zone for H2-rich syngas, and then shifted to the sides of the combustor when syngas percentages were high. The NOx emissions decreased with increasing syngas percentages, but NOx emissions are higher at higher hydrogen content at the same syngas percentage. The CO2 emissions decreased for 10% syngas substitution, but then increased as syngas percentage increased. Only using H2-rich syngas could produce less carbon dioxide. The detailed flame structures, temperature distributions, and gas emissions of the combustor were presented and compared. The exit temperature distributions and pattern factor (PF) were also discussed. Before syngas fuels are utilized as an alternative fuel for the micro gas turbine, further experimental testing is needed as the modeling results provide a guidance for the improved designs of the combustor.

scholarly journals A Method to Measure the Fuel Distribution and the Fuel Captured by V–Gutter Flameholder in High Speed Airstream

1985 ◽  
Author(s):  
Gu Shan-Jian ◽  
Yang Mao-Lin ◽  
Li Xiang-Yi
Keyword(s):  
Flow Rate ◽  
Experimental Error ◽  
High Speed ◽  
Fuel Flow Rate ◽  
Fuel Distribution ◽  
Fuel Flow ◽  
Sampling Condition ◽  
Detailed Determination

A method to measure the fuel distribution and the percentage of fuel flow rate captured by a V-gutter flameholder in a high speed airstream has been developed. The effects of configuration and size of the probe and temprature of the sample mixture in the probe on measurement have been investigated. The detailed determination of isokinetic sampling condition is described. The effects of V-gutter geometry on flowfield have been considered. The total experimental error is of the order ±5%.

System Level Analysis of Acoustically Forced Nonpremixed Swirling Flames

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Uyi Idahosa ◽  
Saptarshi Basu ◽  
Ankur Miglani
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Ccd Camera ◽  
Time Dependent ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Flame Response ◽  
Rate Oscillations ◽  
Swirling Flames ◽  
Flame Sheet

This paper reports an experimental investigation of dynamic response of nonpremixed atmospheric swirling flames subjected to external, longitudinal acoustic excitation. Acoustic perturbations of varying frequencies (fp = 0–315 Hz) and velocity amplitudes (0.03 ≤ u′/Uavg ≤ 0.30) are imposed on the flames with various swirl intensities (S = 0.09 and 0.34). Flame dynamics at these swirl levels are studied for both constant and time-dependent fuel flow rate configurations. Heat release rates are quantified using a photomultiplier (PMT) and simultaneously imaged with a phase-locked CCD camera. The PMT and CCD camera are fitted with 430 nm ±10 nm band pass filters for CH* chemiluminescence intensity measurements. Flame transfer functions and continuous wavelet transforms (CWT) of heat release rate oscillations are used in order to understand the flame response at various burner swirl intensity and fuel flow rate settings. In addition, the natural modes of mixing and reaction processes are examined using the magnitude squared coherence analysis between major flame dynamics parameters. A low-pass filter characteristic is obtained with highly responsive flames below forcing frequencies of 200 Hz while the most significant flame response is observed at 105 Hz forcing mode. High strain rates induced in the flame sheet are observed to cause periodic extinction at localized regions of the flame sheet. Low swirl flames at lean fuel flow rates exhibit significant localized extinction and re-ignition of the flame sheet in the absence of acoustic forcing. However, pulsed flames exhibit increased resistance to straining due to the constrained inner recirculation zones (IRZ) resulting from acoustic perturbations that are transmitted by the co-flowing air. Wavelet spectra also show prominence of low frequency heat release rate oscillations for leaner (C2) flame configurations. For the time-dependent fuel flow rate flames, higher un-mixedness levels at lower swirl intensity is observed to induce periodic re-ignition as the flame approaches extinction. Increased swirl is observed to extend the time-to-extinction for both pulsed and unpulsed flame configurations under time-dependent fuel flow rate conditions.

scholarly journals A new generation of F1 race engines – hybrid power units

2016 ◽  
Vol 167 (4) ◽  
pp. 22-37 ◽  
Author(s):  
Zbigniew STĘPIEŃ
Keyword(s):  
Flow Rate ◽  
Regulatory Framework ◽  
Fuel Flow Rate ◽  
Maximum Performance ◽  
Engine Efficiency ◽  
Hybrid Power ◽  
Fuel Flow ◽  
New Generation ◽  
Technical Regulations

The paper aims at reviewing the evolution of the F1 engine technology and the associated regulatory framework governing the sport over the last 10 years. Technical regulations, in force since 2014, replaced the 2.4-liter V8 naturally aspirated engines with sophisticated hybrid units such as the 1.6-liter V6 turbocharged engines supported with energymanagement and recovery systems. Since 2014 the fundamental trend in the development of powertrains has been the advancement of their efficiency. Due to the fact that the fuel flow rate has been restricted, the maximum performance is now entirely dependent on the engine efficiency.

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