The idea of recovering waste heat, and using it for some useful purpose, is certainly not new. Within vehicular applications, most people are aware, perhaps unknowingly, of some form of waste heat recovery technology. The simplest of these forms is most-likely the utilization of engine waste heat for the purpose of cabin heating. In this instance, the waste heat engine coolant stream simply transfers heat to the cabin, instead of outside air, in order to provide the desired level of passenger comfort. Another common, and more complex, form of waste heat recovery is the use of a turbocharger. In this instance, some of the waste heat from the exhaust stream is used to drive a compressor, via an exhaust-driven turbine, for the purpose of increasing the aerobic potential of an internal combustion engine, which in turn increases its power output. This evolution of waste heat recovery technology from simple thermal waste heat utilization, to thermal mechanical waste heat utilization with the automotive industry is an evolutionary path not unique to this industry, and has subsequently taken place in other areas outside of on-road applications. Of ABSTRACTFuel efficiency for tractor/trailer combinations continues to be a key area of focus for manufacturers and suppliers in the commercial vehicle industry. Improved fuel economy of vehicles in transit can be achieved through reductions in aerodynamic drag, tire rolling resistance, and driveline losses. Fuel economy can also be increased by improving the efficiency of the thermal to mechanical energy conversion of the engine. One specific approach to improving the thermal efficiency of the engine is to implement a waste heat recovery (WHR) system that captures engine exhaust heat and converts this heat into useful mechanical power through use of a power fluid turbine expander.Several heat exchangers are required for this Rankine-based WHR system to collect and reject the waste heat before and after the turbine expander. The WHR condenser, which is the heat rejection component of this system, can be an additional part of the front-end cooling module. Packaging this WHR condenser as part of the front-end cooling module can be an engineering challenge given the tight underhood environment where the current powertrain cooling components are already near system-capable thermal limits. This paper shows how Lattice Boltzmann Method based simulations using highly-detailed vehicle geometry were utilized in the development of the heat exchanger architecture used to meet peak cooling needs as well as provide sufficient cooling airflow to the WHR condenser under all operating conditions. Heat exchanger results from the simulations are shown to compare well to cooling test measurements in a fully-climatic vehicular wind tunnel.
Nitrous oxide can be used for internal combustion engines as a supplemental oxidizer. In a nitrous oxide system the nitrous is stored in a pressurized container or bottle. Under dynamic use, as the nitrous oxide is being spent the mass in the bottle decreases. This decrease in mass leads to a decrease in pressure. The pressure is the source of delivery of the nitrous oxide to the system. Typically nitrous oxide systems do not have a way to maintain a constant oxidizer deliver flow that can adjust to the pressure drop in the bottle as the nitrous oxide is spent. By not having a way to maintain the oxidizer deliver as the bottle pressure drops it becomes hard to stay consistent interms of the Air (Oxidizer) to Fuel ratio (A/F). The net effect of this pressure drop is that the A/F changes. When this happens the performance of the engine may be compromised as well as the health of the engine. One way to maintain the A/F by regulating the pressure the fuel pressure with respect to the nitrous oxide bottle pressure. This regulator is the focus of this project. A pressure regulator would insure that a constant pressure after the regulator could be maintained. The theory behind the regulator has been previously established but the want of a design of a regulator for a certain application has been brought to the design teams attention. A dynamometer test lab based in Milwaukee has offered testing support for the design of a pressure regulator that would maintain a constant A/F mixture delivery. Motorcycles, due to the need for small components, need to have small nitrous oxide bottles when they are set up with nitrous oxide systems. This small bottle empties faster than a large bottle so the need to maintain the A/F is even more applicable for use on a motorcycle.
This research involves the development and testing of a pressure regulator designed to maintain a constant pressure and mass flow relationship between the oxidizer and fuel source of a nitrous oxide injection system. Regulator design was accomplished through the exhaustive process of reviewing various fuel control and oxidizer referencing designs coupled with finite element analysis on the oxidizer referenced components to determine whether the selected components could handle the relatively high forces generated by the 1000psi nitrous oxide. The testing phase of the project was done in a dynamometer cell and involved numerous dynamometer tests of an engine supplied with a nitrous oxide kit both with and without the oxidizer referenced fuel pressure regulator. These tests monitored critical areas such as peak cylinder pressure, the location of the peak cylinder pressure, the air/fuel ratio, the nitrous oxide bottle pressure, and the knock intensity. The data collected in each of these areas was used to compare the performance of a regulated and non-regulated system as well as ensure the safe and reliable operation of the engine.
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