Comparing Expanders for Direct Recovery of Exhaust Energy From a Low-Heat-Rejection Diesel

1987 ◽  
Vol 109 (4) ◽  
pp. 396-401 ◽  
Author(s):  
C. A. Amann
Keyword(s):  
Flow Characteristics ◽  
Constant Speed ◽  
Energy Extraction ◽  
Heat Rejection ◽  
Part Load ◽  
Internal Expansion ◽  
Positive Displacement ◽  
Exhaust Energy ◽  
A Performance

Part-load performance of a compound low-heat-rejection (LHR) engine is estimated at constant speed. The engine consists of an LHR diesel reciprocator geared to a supercharging compressor and an exhaust expander. Two classes of expander differing substantially in both flow characteristics and energy-extraction principles are ranked: aerodynamic (reaction turbine) and positive-displacement (internal expansion). To focus the comparison on differences in fundamental expander characteristics rather than differences in efficiency levels among specific samples of each type of expander, each is assigned an efficiency of 100 percent at its best-efficiency point. Although differences in fundamental characteristics between the expanders were sufficient to rank them on a performance basis, these differences were largely overshadowed by the magnitude of the indicated work developed in the reciprocator relative to the work developed by the expander.

An Improvement of Part Load Performance of Diesel Engines Operating at Constant Speed Conditions

1994 ◽  
Vol 208 (1) ◽  
pp. 21-25 ◽  
Author(s):  
A A Abdel-Rahman ◽  
M K Ibrahim ◽  
A A Said
Keyword(s):  
Fuel Consumption ◽  
Diesel Engines ◽  
Petroleum Refining ◽  
Specific Fuel Consumption ◽  
Constant Speed ◽  
Maximum Pressure ◽  
Brake Specific Fuel Consumption ◽  
Part Load ◽  
Generating Sets ◽  
In Series

This paper discusses the possibility of improving the part load performance of diesel electric turbocharged engines operating at constant speed conditions. A sequential turbocharged system is proposed, where the compressors are connected In series. The study focused on two turbocharged diesel–electric generating sets existing at Ameria Petroleum Refining Company in Alexandria, Egypt. The results of the prediction showed that, at part load, both the maximum pressure and temperature were increased, and the brake specific fuel consumption was reduced considerably (by about 10 per cent).

Modeling Off-Design and Part-Load Performance of Supercritical Carbon Dioxide Power Cycles

2013 ◽  
Author(s):  
John J. Dyreby ◽  
Sanford A. Klein ◽  
Gregory F. Nellis ◽  
Douglas T. Reindl
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Ambient Air ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Heat Rejection ◽  
Power Cycles ◽  
Part Load ◽  
Dry Cooling ◽  
Supercritical Carbon

Continuing efforts to increase the efficiency of utility-scale electricity generation has resulted in considerable interest in Brayton cycles operating with supercritical carbon dioxide (S-CO2). One of the advantages of S-CO2 Brayton cycles, compared to the more traditional steam Rankine cycle, is that equal or greater thermal efficiencies can be realized using significantly smaller turbomachinery. Another advantage is that heat rejection is not limited by the saturation temperature of the working fluid, facilitating dry cooling of the cycle (i.e., the use of ambient air as the sole heat rejection medium). While dry cooling is especially advantageous for power generation in arid climates, the reduction in water consumption at any location is of growing interest due to likely tighter environmental regulations being enacted in the future. Daily and seasonal weather variations coupled with electric load variations means the plant will operate away from its design point the majority of the year. Models capable of predicting the off-design and part-load performance of S-CO2 power cycles are necessary for evaluating cycle configurations and turbomachinery designs. This paper presents a flexible modeling methodology capable of predicting the steady state performance of various S-CO2 cycle configurations for both design and off-design ambient conditions, including part-load plant operation. The models assume supercritical CO2 as the working fluid for both a simple recuperated Brayton cycle and a more complex recompression Brayton cycle.

Unsteady Velocity Field Measurements of Outlet Flow in an Automotive Supercharger

2006 ◽  
Author(s):  
Pranay Mahendra ◽  
Michael G. Olsen
Keyword(s):  
Particle Image Velocimetry ◽  
Automotive Industry ◽  
High Speed ◽  
Particle Image ◽  
Flow Characteristics ◽  
Field Measurements ◽  
Velocity Fields ◽  
Positive Displacement ◽  
Image Velocimetry ◽  
Outlet Flow

Recently the automotive industry has been using superchargers to boost the power generated by the engine, but the noise generated by these superchargers is of great concern. The noise generated during the working of the supercharger is primarily a fluid mechanics phenomenon. Particle Image Velocimetry (PIV) was used to study air flow characteristics of a positive displacement supercharger with an emphasis on gaining insights into strategies for noise reduction. PIV was used to measure the instantaneous and ensemble-averaged velocity fields of the flow at the outlet of the supercharger as a function of blade position, allowing for visualization of the flow as it leave the blades. The preliminary results show that the flow exits the supercharger as a high speed jet at the end closer to the pulley end, and the flow varies with the change in blade position.

Promises and Challenges of the Low-Heat-Rejection Diesel

1988 ◽  
Vol 110 (3) ◽  
pp. 475-481 ◽  
Author(s):  
C. A. Amann
Keyword(s):  
Heat Loss ◽  
Convective Heat ◽  
Cooling System ◽  
Particulate Emissions ◽  
Full Potential ◽  
Engine Fuel ◽  
Heat Rejection ◽  
Convective Heat Loss ◽  
Exhaust Energy ◽  
Liquid Cooling System

The low-heat-rejection (LHR) diesel promises decreased engine fuel consumption by eliminating the traditional liquid cooling system and converting energy normally lost to the coolant into useful shaft work instead. However, most of the cooling energy thus conserved is transferred into the exhaust stream rather than augmenting crankshaft output directly, so exhaust-energy recovery is necessary to realize the full potential of the LHR engine. The higher combustion temperature of the LHR diesel favors increased emission of NOx, with published results on hydrocarbon and particulate emissions showing mixed results. The cylinder insulation used to effect low heat rejection influences convective heat loss only, and in a manner still somewhat controversial. The cyclic aspect of convective heat loss, and radiation from incandescent soot particles, also deserve attention. The temperatures resulting from insulating the cylinder of the LHR diesel require advancements in lubrication. The engine designer must learn to deal with the probabilistic nature of failure in brittle ceramics needed for engine construction. Whether ceramic monoliths or coatings are more appropriate for cylinder insulation remains unsettled. These challenges confronting the LHR diesel are reviewed.

scholarly journals A Low-Cost, Accurate, and High-Precision Fluid Dispensing System for Microscale Application

2016 ◽  
Vol 22 (2) ◽  
pp. 144-152 ◽  
Author(s):  
Champak Das ◽  
Guochun Wang ◽  
Chien Nguyen
Keyword(s):  
Low Cost ◽  
Flow Characteristics ◽  
Positive Displacement ◽  
Real Time Measurement ◽  
Fluid Dispensing ◽  
Accuracy And Precision ◽  
Displacement Pump ◽  
The Individual ◽  
Similar Accuracy ◽  
The Cost

We present here the development of a low-cost, accurate, and precise fluid dispensing system. It can be used with peristaltic or any other pump to improve the flow characteristics. The dispensing system has a range of 1 to 100 µL with accuracy of ~99.5% and standard deviation at ~150 nL over the entire range. The system developed does not depend on the accuracy or precision of the driving pump; therefore, any positive displacement pump can be used to get similar accuracy and precision, which gives an opportunity to reduce the cost of the system. The dispensing system does not require periodic calibration and can also be miniaturized for microfluidic application. Although primarily designed for aqueous liquid, it can be extended for different nonconductive liquids as well with modifications. The unit is further used for near real-time measurement of lactate from microdialysate. The individual components can easily be made disposable or sterilized for use in biomedical applications.

scholarly journals Part Load Performance of the Intercooled Two-Shaft Gas Turbine With Power Output at Constant Speed on the High-Pressure Shaft

1987 ◽  
Author(s):  
N. Gasparovic ◽  
J.-W. Kim
Keyword(s):  
High Pressure ◽  
Power Output ◽  
Gas Turbines ◽  
Internal Heat ◽  
Constant Speed ◽  
Inlet Temperature ◽  
Part Load ◽  
Internal Heat Exchanger ◽  
High Pressure Compressor ◽  
Pressure Compressor

The general analysis of the part load performance of gas turbines indicates that the intercooled cycle with two shafts and power output at constant speed on the high-pressure shaft can have a good part load efficiency. Calculations with fixed geometry of the turbomachines show an intolerable increase of the turbine inlet temperature above the permissible level. By introducing variable geometry in the turbomachines, this disadvantage can be overcome. With variable inlet guide vanes at the high-pressure compressor an excellent part load performance is achieved. Further improvements are possible by adding an internal heat exchanger.

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