Search Results

NASA's proposed lunar lander, Altair, will be exposed to vastly different external temperatures following launch till its final destination on the moon. In addition, the heat rejection is lowest at the lowest environmental temperatures (0.5 kW @ 4K) and highest at the highest environmental temperature (4.5 kW @ 215K). This places a severe demand on the radiator design to handle these extreme turn-down requirements. A radiator with digital turn-down capability is currently under study at JPL as a robust means to meet the heat rejection demands and provide freeze protection while minimizing mass and power consumption. Turndown is achieved by independent control of flow branches with isolating latch valves and a gear pump to evacuate the isolated branches. A bench-top test was conducted to characterize the digital radiator concept. Testing focused on the demonstration of proper valve sequencing to achieve turn-down and recharge of flow legs.

The pursuit of greater fuel economy in internal combustion engines requires the optimization of all subsystems including thermal management. The reduction of cooling power required by the electromechanical coolant pump, radiator fan(s), and thermal valve demands real time control strategies. To maintain the engine temperature within prescribed limits for different operating conditions, the continual estimation of the heat removal needs and the synergistic operation of the cooling system components must be accomplished. The reductions in thermal management power consumption can be achieved by avoiding unnecessary overcooling efforts which are often accommodated by extreme thermostat valve positions. In this paper, an optimal nonlinear controller for a military M-ATV engine cooling system will be presented. The prescribed engine coolant temperature will be tracked while minimizing the pump, fan(s), and valve power usage.

Hybrid vehicle embedded systems and payloads require progressively more accurate and versatile thermal control mechanisms and strategies capable of withstanding harsh environments and increasing power density. The division of the cargo and passenger compartments into convective thermal zones which are independently managed can lead to a manageable temperature control problem. This study investigates the performance of a Peltier-effect thermoelectric zone cooling system to regulate the temperature of target objects (e.g., electronic controllers, auxiliary computer equipment, etc) within ground vehicles. Multiple thermoelectric cooling modules (TEC) are integrated with convective cooling fans to provide chilled air for convective heat transfer from a robust, compact, and solid state device. A series of control strategies have been designed and evaluated to track a prescribed time-varying temperature profile while minimizing power consumption.

The challenge of meeting the Corporate Average Fuel Economy (CAFE) standards of 2025 has led to major developments in the transportation sector, among which is the attempt to utilize clean energy sources. To date, use of solar energy as an auxiliary source of on-board fuel has not been extensively investigated. This paper is the first study at undertaking a comprehensive analysis of using solar energy on-board by means of photovoltaic (PV) technologies to enhance automotive fuel economies, extend driving ranges, reduce greenhouse gas (GHG) emissions, and ensure better economic value of internal combustion engine (ICE) -based vehicles to meet CAFE standards though 2025. This paper details and compares various aspects of hybrid solar electric vehicles with conventional ICE vehicles.

This paper argues the importance of engineering heuristics and introduces an educational data-driven tool to help novice engineers develop their engineering heuristics more effectively. The main objective in engineering practice is to identify opportunities for improvement and apply methods to effect change. Engineers do so by applying ‘how to’ knowledge to make decisions and take actions. This ‘how to’ knowledge is encoded in engineering heuristics. In this paper, we describe a tool that aims to provide heuristic knowledge to users by giving them insight into heuristics applied by experts in similar situations. A repository of automotive data is transformed into a tool with powerful search and data visualization functionalities. The tool can be used to educate novice automotive engineers alongside the current resource intensive practices of teaching engineering heuristics through social methods such as an apprenticeship.

The automotive cooling system configuration has remained fixed for many decades with a large radiator plus fan, coolant pump, and bypass valve. To reduce cooling system power consumption, the introduction of multiple computer-controlled heat exchangers may offer some benefits. A paradigm shift from a single large radiator, sized for maximum load, to n-small radiators with individual flow control valves should allow fine tuning of the heat rejection needs to minimize power. In this project, a series of experimental scenarios featuring two identical parallel radiators have been studied for low thermal load engine cooling (e.g., idling) in ground transportation applications. For high thermal load scenarios using two radiators, the fans required between 1120 - 3600 W to maintain the system about the coolant reference temperature of 85oC.

Recovery of potable water from wastewater is essential for the success of long-term manned missions to the moon and Mars. Honeywell International and the team consisting of Thermodistillation Company (Kyiv, Ukraine) and NASA Johnson Space Center (JSC) Crew and Thermal Systems Division are developing a wastewater processing subsystem that is based on centrifugal vacuum distillation. The Wastewater Processing Cascade Distillation Subsystem (CDS) utilizes an innovative and efficient multi-stage thermodynamic process to produce purified water. The rotary centrifugal design of the system also provides gas/liquid phase separation and liquid transport under microgravity conditions. A five-stage prototype of the subsystem was built, delivered and integrated into the NASA JSC Advanced Water Recovery Systems Development Facility for development testing.

This paper proposes a conceptual design tool that could direct designers towards concepts that lead to reduced gaps on the exterior of an automobile. Apart from the manufacturing and assembly tolerance stack up, the design and integration method of the body panels in an automobile contribute to the gap. . A benchmark study suggested cursory concepts to avoid or minimize the gaps. The proposed design tool uses a modified morphological chart approach to populate a table with concepts obtained from the benchmark study and by other means. The design tool also incorporates decision alternatives and hence is different from a morphological chart. The design tool can be used to highlight the occurrence of a high level tolerance stack up chain on the structural/mounting members. Conceptual component architectures are arranged in such a fashion to facilitate combinations through visual means.

The Equivalent System Mass (ESM) metric developed by NASA describes and compares individual system impact on a closed system in terms of a single parameter, mass. The food system of a Mars mission may encompass a large percentage of total mission ESM, and decreasing this ESM would be beneficial. Yeast breads were made using three methods (hand & oven, bread machine, mixer with dough hook attachment & oven). Flat breads were made using four methods (hand & oven, hand & griddle, mixer with dough hook attachment & oven, mixer with dough hook attachment & griddle). Two formulations were used for each bread system (scratch ingredients, commercial mix). ESM was calculated for each of these scenarios. The objective of this study was to compare the ESM of yeast and flat bread production for a Martian surface outpost. Method (equipment) for both types of bread production was demonstrated to be the most significant influence of ESM when one equipment use was assumed.

Conceptual designs for a space suit Personal Life Support Subsystem (PLSS) were developed and assessed to determine if upgrading the system using new, emerging, or projected technologies to fulfill basic functions would result in mass, volume, or performance improvements. Technologies were identified to satisfy each of the functions of the PLSS in three environments (zero-g, Lunar, and Martian) and in three time frames (2006, 2010, and 2020). The viability of candidate technologies was evaluated using evaluation criteria such as safety, technology readiness, and reliability. System concepts (schematics) were developed for combinations of time frame and environment by assigning specific technologies to each of four key functions of the PLSS -- oxygen supply, waste removal, thermal control, and power. The PLSS concepts were evaluated using the ExtraVehicular Activity System Sizing Analysis Tool, software created by NASA to analyze integrated system mass, volume, power and thermal loads.

Debris in the Orbiter crew compartment of early Shuttle missions created crew health concerns and physiological discomfort, and was the cause of some equipment malfunctions. Debris from Orbiters during flight and processing was analyzed, quantized, and evaluated to determine its source. Records were kept on the amount of debris vacuumed by the crew during on-orbit cleaning and the amount found on air-cooled avionics boxes during ground turnaround. After ground turnaround operations at Kennedy Space Center and Palmdale were reviewed from a facility, materials use, and materials control standpoint, the following remedial steps were taken.

Wheat is a candidate crop for the Advanced Life Support (ALS) system, and cereal grains and their products will be included on long-term space missions beyond low earth orbit. While the exact supply scenario has yet to be determined, some type of post-processing of these grains must occur if they are shipped as bulk ingredients or grown on site for use in foods. Understanding the requirements for processing grains in space is essential for incorporating the process into the ALS food system. The ESM metric developed by NASA describes and compares individual system impact on a closed system in terms of a single parameter, mass. The objective of this study was to compare the impact of grain mill type on the ESM of producing yeast and flat breads. Hard red spring wheat berries were ground using a Brabender Quadrumat Jr. or the Kitchen-Aid grain mill attachment (both are proposed post-harvest technologies for the ALS system) to produce white and whole wheat flour, respectively.

NASA-JSC is evaluating planetary mission scenarios where plants will provide the majority of the diet for the crew. The requirements of both plants and crew diet need to be integrated in the development of the final food system. Plant growth has limitations in type and quantity of crops to be produced while diets must meet palatability and nutritional requirements as well as limited processing labor, equipment and power. A plan is presented for the development of a food system based heavily on grown crops. Although the steps taken in the development are applicable to the design of any long duration flight food system. The process begins with the development of a food list, followed by preliminary menu design, nutritional analysis and finally menu testing.

A single radiator cooling system architecture has been widely applied in ground vehicles for safe equipment (e.g., engine block, electronics, and motors) temperature control. The introduction of multiple smaller heat exchangers provides additional energy management features and alternate pathways for continued operation in case of critical subsystem failure. Although cooling performance is often designed for maximum thermal loads, systems typically operate at a fraction of the peak values for most of their life cycle. In this project, a two-radiator configuration with variable flow rates and valve positions has been mathematically modelled and experimentally validated to study its performance feasibility. A multi-node resistance-capacitance thermal model was derived using the ε−NTU approach with accompanying convective and conductive heat transfer pathways within the system.

Electrified transportation has received significant interest recently because of sustainable and clean energy goals. However, the degradation of electrical components such as energy storage systems raises system reliability and economic concerns. In this paper, a prognostic-based control strategy is proposed for hybrid electric vehicles (HEVs) to abate the degradation of energy systems. Degradation forecasting models of electrical components are developed to predict their degradation paths. The predicted results are then used to control HEVs in order to reduce the degradation of components.

Over the years, the complexity of autonomous vehicle development (and concurrently the verification and validation) has grown tremendously in terms of component-, subsystem- and system-level interactions between autonomy and the human users. Simulation-based testing holds significant promise in helping to identify both problematic interactions between component-, subsystem-, and system-levels as well as overcoming delays typically introduced by the default full-scale on-road testing. Software in Loop (SiL) simulation is utilized as an intermediate step towards software deployment for autonomous vehicles (AV) to make them reliable. SiL efforts can help reduce the resources required for successful deployment by helping to validate the software for millions of road miles. A key enabler for accelerating SiL processes is the ability to use Simulation as a Service (SaaS) rather than just isolated instances of software.

Strategies for evaluating the impact of mission requirements on the design of mission-specific vehicles are needed to enable project managers to assess potential benefits and associated costs of changes in requirements. Top-level requirements that cause significant cascaded difficulties on lower-level requirements should be identified and presented to decision-makers. This paper aims to introduce formal methods and computational tools to enable the analysis and allocation of mission requirements.

Automotive and truck manufacturers are introducing electric propulsion systems into their ground vehicles to reduce fossil fuel consumption and harmful tailpipe emissions. The mobility shift to electric motors requires a compact thermal management system that can accommodate heat dissipation demands with minimum energy consumption in a confined space. An innovative cooling system design, emphasizing passive cooling methods coupled with a small liquid system, using a thermal bus architecture has been explored. The laboratory experiment features an emulated electric motor interfaced to a thermal cradle and multiple heat rejection pathways to evaluate the transfer of generated heat to the ambient surroundings. The thermal response of passive (e.g., carbon fiber, high thermal conductivity material, thermosyphon) and active cooling systems are investigated for two operating scenarios.

Enhanced electric motor performance in transportation vehicles can improve system reliability and durability over rigorous operating cycles. The design of innovative heat rejection strategies in electric motors can minimize cooling power consumption and associated noise generation while offering configuration flexibility. This study investigates an innovative electric motor cooling strategy through bench top thermal testing on an emulated electric motor. The system design includes passive (e.g., heat pipes) cooling as the primary heat rejection pathway with supplemental conventional cooling using a variable speed coolant pump and radiator fan(s). The integrated thermal structure, “cradle”, transfers heat from the motor shell towards an end plate for heat dissipation to the ambient surroundings or transmission to an external thermal bus to remote heat exchanger.

Designing an efficient cooling system with low power consumption is of high interest in the automotive engineering community. Heat generated due to the propulsion system and the on-board electronics in ground vehicles must be dissipated to avoid exceeding component temperature limits. In addition, proper thermal management will offer improved system durability and efficiency while providing a flexible, modular, and reduced weight structure. Traditional cooling systems are effective but they typically require high energy consumption which provides motivation for a paradigm shift. This study will examine the integration of passive heat rejection pathways in ground vehicle cooling systems using a “thermal bus”. Potential solutions include heat pipes and composite fibers with high thermal properties and light weight properties to move heat from the source to ambient surroundings.