Strategy on performance improvement of inverse Brayton cycle system for energy recovery in turbocharged diesel engines

2019 ◽  
Vol 234 (1) ◽  
pp. 85-95
Author(s):  
Dengting Zhu ◽  
Yun Lin ◽  
Xinqian Zheng
Keyword(s):  
Heat Exchanger ◽  
Performance Improvement ◽  
Diesel Engines ◽  
Energy Recovery ◽  
Engine Speed ◽  
Critical Parameters ◽  
Absolute Pressure ◽  
Brayton Cycle ◽  
Cycle System ◽  
The Future

The inverse Brayton cycle is a potential technology for waste heat energy recovery. It consists of three components: one turbine, one heat exchanger, and one compressor. The exhaust gas is further expanded to subatmospheric pressure in the turbine, and then cooled in the heat exchanger, last compressed in the compressor into the atmosphere. The process above is the reverse of the pressurized Brayton cycle. This work has presented the strategy on performance improvement of the inverse Brayton cycle system for energy recovery in turbocharged diesel engines, which has pointed the way to the future development of the inverse Brayton cycle system. In the paper, an experiment was presented to validate the numerical model of a 2.0 l turbocharged diesel engine. Meanwhile, the influence laws of the inverse Brayton cycle system critical parameters, including turbocharger speed and efficiencies, and heat exchanger efficiency, on the system performance improvement for energy recovery are explored at various engine operations. The results have shown that the engine exhaust energy recovery efficiency increases with the engine speed up, and it has a maximum increment of 6.1% at the engine speed of 4000 r/min (the engine rated power point) and the full load. At the moment, the absolute pressure was before final compression is 51.9 kPa. For the inverse Brayton cycle system development in the future, it is essential to choose a more effective heat exchanger. Moreover, variable geometry turbines are very appropriate to achieve a proper matching between the turbocharging system and the inverse Brayton cycle system.

Experimental Analysis of an Air-to-Air Heat Exchanger for Use in a Refrigeration Brayton Cycle

Volume 3 ◽  
2004 ◽  
Author(s):  
Alireza Kargar ◽  
Mohammad H. Hosni ◽  
Steve Eckels ◽  
Tomas Gielda
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Removal Rate ◽  
Experimental Results ◽  
Airflow Rate ◽  
Brayton Cycle ◽  
Moisture Removal ◽  
Research Project ◽  
Cycle System ◽  
Automotive Air Conditioning

The refrigeration Brayton cycle, which has been used extensively in various industries, has an excellent potential for use in automotive air conditioning applications. However, the air-cycle system has a couple of drawbacks including fog generation and low cycle efficiency. In this research project, an air-to-air heat exchanger called a ‘mixer’ is designed and used at the outlet of a refrigeration Brayton cycle. The primary function of the mixer is to remove moisture from the secondary warm airflow into the system. Successful moisture removal from the secondary airflow results in achieving the second function of fog dissipation from the primary cold airflow. In order for the system to perform appropriately, the moisture removal rate must be kept at the highest possible rate. The experimental results from this research project reveal that to enhance moisture removal rate, one may either increase the primary cold airflow rate, decrease the secondary warm airflow rate, or the combination of the above airflow adjustments. Furthermore, based on experimental results, one may speculate that there is an optimum point in decreasing the secondary airflow rate. However, in increasing the primary airflow rate, one must be aware of the pressure drop through the cold side of the mixer as the higher pressure drop results in higher power consumption for the Brayton cycle. It is important to point out that appropriate levels of the primary and secondary airflows impacts the mixer effectiveness, and that for a constant cold airflow rate, decreasing the warm airflow rate below the cold airflow rate results in higher effectiveness.

An Analog Computer Simulation of a Closed Brayton Cycle System

1969 ◽  
Author(s):  
F. D. Jordan ◽  
M. R. Hum ◽  
A. N. Carras
Keyword(s):  
Computer Simulation ◽  
Thermal Inertia ◽  
Experimental Information ◽  
Analog Computer ◽  
Critical Parameters ◽  
Total System ◽  
Brayton Cycle ◽  
Pressure Losses ◽  
Cycle System ◽  
The Mathematical Model

A summary of the Mathematical Model, Analog Computer Simulation, and experimental information comparison of a representative Closed Brayton Cycle System is presented. The foundation of the simulation, are design, experimentation, and analysis efforts performed on full-sized Closed Brayton Cycle System components. The analog computer program shows total system interaction and component behavior, both steady-state and dynamic modes, over the entire system operating range. In order to accurately describe a complete Closed Brayton Cycle System, practical details such as auxiliary components, system parasitic losses, variation of thermodynamic properties, thermal inertia, variability of pressure losses, and transient disturbances constitute an important part of the formulation. The development of the analog computer simulation provides an economical and effective method for system performance prediction, identification of critical parameters, systems integration, and component optimization.

The Role of the Ceramic Heat Exchanger in Energy and Resource Conservation

1980 ◽  
Vol 102 (2) ◽  
pp. 303-315 ◽  
Author(s):  
C. F. McDonald
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
Energy Recovery ◽  
Waste Heat ◽  
Industrial Applications ◽  
Utilization Efficiency ◽  
Process Efficiency ◽  
Exhaust Heat ◽  
The Future

The approaching era of strict energy conservation and eventual energy shortage will have a profound effect on the design of process and power-producing plants, since in the future maximum fuel utilization efficiency will be of the essence. The intrinsic economic worth of industrial reject and exhaust heat is too great to merely discharge to the environment, and means of utilizing this energy by improved process efficiency, or by cogeneration, must be quickly brought to the commercial stage. For future power conversion systems, and in particular open- and closed-cycle gas turbines, emphasis will be placed on maximizing efficiency, and in many cases this can be achieved only by significant increases in operating temperatures. For future gas turbines, process heat plants, chemical plants, basic industries, and waste heat recovery applications, the high level of reject temperature will necessitate the utilization of ceramic heat exchangers for thermal energy recovery. In this paper, current development activities in the field of ceramic heat exchangers for gas turbine applications are discussed, and it is projected that the encouraging results from these programs will stimulate a broader interest in high-temperature waste heat energy recovery. The future role the ceramic heat exchanger will play in energy recovery for different industrial applications is emphasized, and appropriate heat exchanger design criteria, types of construction, surface geometries, and development activities are briefly discussed.

PARAMETRIC STUDY ON AIR BRAYTON CYCLE AS AN EXHAUST ENERGY RECOVERY METHOD

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
Aaron Edward Teo ◽  
Srithar Rajoo ◽  
Meng Soon Chiong ◽  
Kishokanna Paramasivam ◽  
Fengxian Tan
Keyword(s):  
Heat Exchanger ◽  
Diesel Engine ◽  
Parametric Study ◽  
Energy Recovery ◽  
Brayton Cycle ◽  
Brake Specific Fuel Consumption ◽  
Fuel Utilization ◽  
Recovery Method ◽  
Exhaust Energy ◽  
Main Components

Exhaust energy recovery is one of the ways to improve engine’s fuel utilization. Parametric study of Air Brayton Cycle (ABC) as an exhaust energy recovery was done to see its feasibility. Parameters such as the mass flow rate, heat exchanger effectiveness, compressor and turbine efficiencies and heat exchanger pressure drop were analyzed to see their effects. It was found that the ABC can extract up to 3-4 kW of energy from the exhaust of a 5.9 liter diesel engine. This translates to about 3-4% of Brake Specific Fuel Consumption (BSFC) improvement. Careful integration of the main components is crucial to the success of the ABC as an exhaust energy recovery.

An Improved Rate of Heat Release Model for Modern High-Speed Diesel Engines

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Peter G. Dowell ◽  
Sam Akehurst ◽  
Richard D. Burke
Keyword(s):  
Heat Release ◽  
Diesel Engines ◽  
Engine Speed ◽  
Fuel Injection ◽  
Maximum Pressure ◽  
Injection Model ◽  
Wall Impingement ◽  
Small Set ◽  
Rate Of Heat Release ◽  
Engine System

To meet the increasingly stringent emissions standards, diesel engines need to include more active technologies with their associated control systems. Hardware-in-the-loop (HiL) approaches are becoming popular where the engine system is represented as a real-time capable model to allow development of the controller hardware and software without the need for the real engine system. This paper focusses on the engine model required in such approaches. A number of semi-physical, zero-dimensional combustion modeling techniques are enhanced and combined into a complete model, these include—ignition delay, premixed and diffusion combustion and wall impingement. In addition, a fuel injection model was used to provide fuel injection rate from solenoid energizing signals. The model was parameterized using a small set of experimental data from an engine dynamometer test facility and validated against a complete data set covering the full engine speed and torque range. The model was shown to characterize the rate of heat release (RoHR) well over the engine speed and load range. Critically, the wall impingement model improved R2 value for maximum RoHR from 0.89 to 0.96. This was reflected in the model's ability to match both pilot and main combustion phasing, and peak heat release rates derived from measured data. The model predicted indicated mean effective pressure and maximum pressure with R2 values of 0.99 across the engine map. The worst prediction was for the angle of maximum pressure which had an R2 of 0.74. The results demonstrate the predictive ability of the model, with only a small set of empirical data for training—this is a key advantage over conventional methods. The fuel injection model yielded good results for predicted injection quantity (R2 = 0.99) and enabled the use of the RoHR model without the need for measured rate of injection.

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