The Hydrogen/Petrol Engine - The Means to Give Good Part-Load Thermal Efficiency

1982 ◽  
Author(s):  
G. G. Lucas ◽  
W. L. Richards
Keyword(s):  
Thermal Efficiency ◽  
Petrol Engine ◽  
Part Load

Effect of Ethanol on Part Load Thermal Efficiency and CO2 Emissions of SI Engines

2013 ◽  
Vol 6 (1) ◽  
pp. 456-469 ◽  
Author(s):  
Hosuk H. Jung ◽  
Michael H. Shelby ◽  
Charles E. Newman ◽  
Robert A. Stein
Keyword(s):  
Co2 Emissions ◽  
Thermal Efficiency ◽  
Part Load ◽  
Si Engines

scholarly journals OBSERVATIONAL ANALYSIS ON RESULT OF YSZ COATED PISTON CROWN ON THE BEHAVIOUR OF A PETROL ENGINE

2021 ◽  
pp. 153-160
Author(s):  
Muhammad Asad Riaz
Keyword(s):  
Thermal Barrier Coating ◽  
Thermal Efficiency ◽  
Mechanical Efficiency ◽  
Yttria Stabilized Zirconia ◽  
Petrol Engine ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Piston Engine ◽  
Piston Crown ◽  
Barrier Coating

An observational study of thermal barrier coating (TBC) on the working of 4-stroke single cylinder petrol engine was studied. Yttria Stabilized Zirconia (YSZ) used as coating material. YSZ has less thermal conductivity, sustainability under high temperature and pressure. Main aim of TBC is to decrease heat losses to the cooling jacket of the engine. YSZ is coated on the piston crown by Plasma spray method. YSZ coating improves the performance of petrol engine. Experimental study was carried out on 4-stroke single cylinder OHV petrol engine 25‎°C inclined cylinder horizontal shaft engine on performance of ceramic coated engine and compared with baseline engine under different speed. Results show that ceramic coated engine is more effective than conventional engine as brake specific fuel consumption (BSFC) is reduced 2-4% than normal piston engine, brake thermal efficiency (BTE) of modified engine is expanded 4-8% than unmodified engine. Indicated thermal efficiency (ITE) of modified piston engine is increased 5-10% than normal engine. Mechanical efficiency (ME) of the TBC engine is increased 4-10% than standard engine. Volumetric efficiency (VE) of modified engine is decreased 3-9% when compared with standard engine and exhaust gas temperature (EGT) of ceramic coated engine is increased 1-3% than unmodified engine. KEYWORDS: Petrol Engine, Thermal barrier coating (TBC), Yttria Stabilized Zirconia (YSZ). Mechanical Efficiency

Semi-Closed Recuperated Cycle With Wet Compression

2017 ◽  
Author(s):  
Hans E. Wettstein
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Specific Power ◽  
Efficiency Gain ◽  
Lower Efficiency ◽  
Part Load ◽  
Thermal Transients ◽  
Wet Compression ◽  
Main Compressor

The semi-closed recuperated cycle (SCRC) has been suggested earlier by the author in several versions. The best of them used two compressors with one intercooling stage each. In this paper the intercooled main compressor has been replaced by a compressor with high fogging and no intercooling anymore. It is assumed that the system and the main compressor have its design points in the middle of the intended fogging water injection range. This turns out to allow another thermal efficiency gain by 2 to 3 percent points to clearly above 60% also combined with increased specific power related to the consumed combustion air and with no bottoming cycle. This paper demonstrates the technical feasibility based on Turbomachinery technologies, which have already proven commercial viability. The thermodynamic assumptions have been derived from existing gas turbine (GT) technology and are used within already confirmed operating ranges. With the same firing temperature also the thermal efficiency level of current Combined Cycles (GTCC) can be achieved. A special feature of the SCRC is the opportunity for inventory control of part load operation. This means that part load operation can be made by pressure reduction instead of temperature reduction as in open gas turbines. Thermal transients leading to hot part life consumption can therefore be avoided to a large extent and the combustor can operate at nearly constant temperature also at low part load with corresponding low emissions. Low part load operation achieves the same efficiency as base load. The result is more flexibility than in current GTCC technology associated with less complexity due to the needlessness of an extra bottoming cycle. Realizing this type of cycle aiming at its best efficiency potential however needs the development capability of a highly skilled gas turbine manufacturer. But it could also be developed for a lower efficiency range by using existing components with conservative data. The SCRC concept could also be aimed at combined heat and power applications or at naval propulsion by replacing CODOG’s. Due to its specific features the SCRC in general or with wet compression could be developed in the micro turbine power output size as well as up to above 1000MW single block size. Its inherent water condensation at elevated pressure makes an external source of make-up water obsolete.

scholarly journals Off-Design Performance Comparison Between Single and Two-Shaft Engines: Part 1 — Fixed Geometry

2020 ◽  
Author(s):  
Th. Nikolaidis ◽  
A. Pellegrini ◽  
H. I. H. Saravanamuttoo ◽  
I. Aslanidou ◽  
A. Kalfas ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Thermal Efficiency ◽  
Rotational Speed ◽  
Pressure Ratio ◽  
Performance Comparison ◽  
Part Load ◽  
Design Performance ◽  
Research Activities ◽  
Compressor Pressure Ratio

Abstract This paper describes an investigation into the off-design performance comparison of single and two-shaft gas turbine engines. A question that has been asked for a long time which gas turbine delivers a better thermal efficiency at part load. The authors, notwithstanding their intensive searches, were unable to find a comprehensive answer to this question. A detailed investigation was carried out using a state of the art performance evaluation method and the answer was found to be: It depends! In this work, the performance of two engine configurations is assessed. In the first one, the single-shaft gas turbine operates at constant shaft rotational speed. Thus, the shape of the compressor map rotational speed line will have an important influence on the performance of the engine. To explore the implications of the shape of the speed line, two single-shaft cases are examined. The first case is when the speed line is curved and as the compressor pressure ratio falls, the non-dimensional mass flow increases. The second case is when the speed line is vertical and as the compressor pressure ratio falls, the non-dimensional mass flow remains constant. In the second configuration, the two-shaft engine, the two-shafts can be controlled to operate at different rotational speeds and also varying relationships between the rotational speeds. The part-load operation is characterized by a reduction in the gas generator rotational speed. The tool, which was used in this study, is a 0-D whole engine simulation tool, named Turbomatch. It was developed at Cranfield and it is based on mass and energy balance, carried out through an iterative method, which is based on component maps. These generic, experimentally derived maps are scaled to match the design point of a particular engine before an off-design calculation is performed. The code has been validated against experimental data elsewhere, it has been used extensively for academic purposes and the research activities that have taken place at Cranfield University. For an ideal cycle, the single-shaft engine was found to be a clear winner in terms of part-load thermal efficiency. However, this picture changed when realistic component maps were utilized. The basic cycle and the shape of component maps had a profound influence on the outcome. The authors explored the influence of speed line shapes, levels of component efficiencies and the variation of these component efficiencies within the operating range. This paper describes how each one of these factors, individually, influences the outcome.

A Gas Turbine Cycle Selection Issue: Recuperated or ICR

2007 ◽  
Author(s):  
Colin Rodgers ◽  
Aubrey Stone ◽  
David White
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Heat Dissipation ◽  
Cycle Performance ◽  
Specific Power ◽  
Exhaust Emission ◽  
Inlet Temperature ◽  
Part Load ◽  
Pressure Losses ◽  
Exhaust Temperature

The intercooled recuperative gas turbine (ICR) potentially offers the advantages of higher specific power, and improved thermal efficiency compared to the recuperative gas turbine, such advantages are however contingent upon the additional parasitic encumbrances of the intercooler heat dissipation or recovery apparatus and pressure losses, plus flowpath ducting and complexity. The thermodynamic performances, relative sizing and relative costs of both an ICR and recuperative gas turbine engine, with a thermal efficiency goal approaching 40%, combined with low exhaust emission requirements were studied. The study encompassed primary candidate engine flowpath configurations comprising of single shaft, two shaft, and two spool designs, with both recuperation (R), and combined Intercooling and Recuperation (ICR). In conducting the study all engine flowpaths were sized for 300kW with a maximum turbine inlet temperature of 1837F (1000C), representative of conservative life limits for conventional un-cooled superalloy turbine rotors. Heat exchanger effectivenesses of the intercooler and recuperator were selected at 80 and 85%, as a compromise between cost, weight, and thermal efficiency considerations. The study confirmed that the simple recuperated cycle is capable of comparable peak thermal efficiency levels to the ICR provided that ICR intercooling parasitic losses are duly accounted, and furthermore has intrinsically lower manufacturing and development costs than the ICR. The cycle performance code used for the studies included prediction of engine exhaust emissions, part load characteristics, and compressor operating lines. The emissions assessment slightly favored the ICR as a consequence of its higher specific power. Assuming part load operation at variable speed and constant turbine exhaust temperature, the two spool ICR showed slightly better part load fuel economy than a recuperated engine.

Torch Ignition: Ideal for Lean Burn Premixed-Charge Engines

1994 ◽  
Vol 116 (4) ◽  
pp. 793-798 ◽  
Author(s):  
N. S. Mavinahally ◽  
D. N. Assanis ◽  
K. R. Govinda Mallan ◽  
K. V. Gopalakrishnan
Keyword(s):  
Combustion Chamber ◽  
Fuel Economy ◽  
Thermal Efficiency ◽  
Lean Burn ◽  
Ignition System ◽  
Part Load ◽  
Full Load ◽  
Spark Plug ◽  
Initiation And Propagation ◽  
Load Conditions

Sluggish flame initiation and propagation, and even potential misfiring, become major problems with lean-fueled, premixed-charge, spark-ignited engines. This work studies torch ignition as a means for improving combustion, fuel economy, and emissions of a retrofitted, large combustion chamber with nonideal spark plug location. A number of alternative configurations, employing different torch chamber designs, spark-plug locations, and materials, were tested under full-load and part-load conditions. Results indicate a considerable extension of the lean operating limit of the engine, especially under part-load conditions. In addition, torch ignition can lead to substantial thermal efficiency gains for either leaner or richer air-fuel ratios than the optimum for the conventional ignition system. On the richer side, in particular, the torch-ignited engine is capable of operating at maximum brake torque spark timings, rather than compromised, knock-limited spark timings used with conventional ignition. This translates into thermal efficiency improvements as high as 8 percent at an air-fuel ratio of 20:1 and full load.

Part-Load Performance of MCFC/APT Hybrid Power System

2008 ◽  
Author(s):  
Y. Tsujikawa ◽  
S. Terashima ◽  
T. Yamauchi ◽  
S. Katsura ◽  
K. Kaneko
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Output ◽  
Thermal Efficiency ◽  
Operation Mode ◽  
Total Power ◽  
Efficient Operation ◽  
Hybrid Power System ◽  
Part Load ◽  
Hybrid Power

High temperature fuel cell such as SOFC or MCFC/turbo machinery hybrid power system has been theoretically demonstrated that it can achieve higher thermal efficiency than any other power generation schemes. Authors had already executed performance analysis of both outer and inner reforming type MCFC/APT (atmospheric pressure turbine) hybrid power systems. In the APT, turbine expansion, cooling by heat exchanger and draft by compressor are made in an open cycle mode. Results in those studies show the total thermal efficiency (electric efficiency) based on a MCFC/APT hybrid power system can be expected more than 65 percent at design point condition. In the present paper, part-load characteristics of MCFC/APT hybrid power system, of which total power output is 100 kW, are investigated for its prospective use in the small distributed energy systems. A cycle analysis of the hybrid system has been performed to obtain general strategies of highly efficient operation and control. A typical operation mode, i.e., variable rotational speed APT operation, is considered. It is found that the generation efficiency can be maintained over 50 percent (LHV) in the power output range from 50 to 100 percent.

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