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During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut's metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment, the load from the electrical components and incident radiation. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Radiators have no moving parts and are thus simple and highly reliable. However, past freezable radiators have been too heavy.

This project investigates methods to capture an astronaut's exhaled carbon dioxide (CO2) before it becomes diluted with the high volumetric oxygen flow present within a space suit. Typical expired breath contains CO2 partial pressures (pCO2) in the range of 20-35 mm Hg (.0226-.046 atm). This research investigates methods to capture the concentrated CO2 gas stream prior to its dilution with the low pCO2 ventilation flow. Specifically this research is looking at potential designs for a collection cup for use inside the space suit helmet. The collection cup concept is not the same as a breathing mask typical of that worn by firefighters and pilots. It is well known that most members of the astronaut corps view a mask as a serious deficiency in any space suit helmet design. Instead, the collection cup is a non-contact device that will be designed using a detailed Computational Fluid Dynamic (CFD) analysis of the ventilation flow environment within the helmet.

The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning to compare the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source.

Absorption cooling using a lithium chloride/water heat pump can enable lightweight and effective thermal control for Extravehicular Activity (EVA) suits without venting water to the environment. The key components in the system are an absorber/radiator that rejects heat to space and a flexible evaporation cooling garment that absorbs heat from the crew member, This paper describes progress in the design, development, and testing of the absorber/radiator and evaporation cooling garment. New design concepts and fabrication approaches will significantly reduce the mass of the absorber/radiator. We have also identified materials and demonstrated fabrication approaches for production of a flexible evaporation cooling garment, Data from tests of the system's modular components have validated the design models and allowed predictions of the size and weight of a complete system.

The Advanced Integration Matrix (AIM) will design a ground-based test facility for developing revolutionary integrated systems for joint human-robotic missions in order to study and solve systems-level integration issues for exploration missions beyond Low Earth Orbit (LEO). This paper describes development plans for educational outreach activities related to technological and operational integration scenarios similar to the challenges that will be encountered through this project. The education outreach activities will provide hands-on, interactive exercises to allow students of all levels to experience design and operational challenges similar to what NASA deals with everyday in performing the integration of complex missions. These experiences will relate to and impact students' everyday lives by demonstrating how their interests in science and engineering can develop into future careers, and reinforcing the concepts of teamwork and conflict resolution.

Advanced engine cooling systems can enhance the combustion environment, increase fuel efficiency, and reduce tailpipe emissions with less parasitic engine load. The introduction of computer controlled electro-mechanical valves, radiator fans, and coolant pumps require mathematic models and real time algorithms to implement intelligent thermal control strategies for prescribed engine temperature tracking. Smart butterfly valves can replace the traditional wax-based thermostat to control the coolant flow based on both engine temperature and operating conditions. The electric water pump and radiator fan replace the mechanically driven components to reduce unnecessary engine loads at high speeds and provide better cooling at low speeds.

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.

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.

As a key component in its ground test bed capability, NASA's Advanced Life Support Program has been developing a large-scale advanced life support facility capable of supporting long-duration testing of integrated bioregenerative life support systems with human test crews. This facility, the Bioregenerative Planetary Life Support Systems Test Complex (BIO-Plex), is currently under development at the Johnson Space Center. The BIO-Plex is comprised of a set of interconnected test chambers with a sealed internal environment capable of supporting test crews of four individuals for periods exceeding one year. The life support systems to be tested will consist of both biological and physicochemical technologies and will perform all required air revitalization, water recovery, biomass production, food processing, solid waste processing, thermal management, and integrated command and control functions.

This paper describes a computational approach to investigating spoke vibrations in cast polyurethane spoked wheels during high-speed rolling. It focuses on four aspects: 1) Creating a two-dimensional finite element model of a cast polyurethane rolling wheel which is in contact with a rigid plane to observe the spoke vibrations. 2) Investigating the effect of rolling speed on the observed spoke vibrations. 3) Investigating the effect of spoke thickness on spoke vibration frequencies. 4) Creating a three-dimensional spoke model to investigate spoke vibrations which exhibit both symmetric and anti-symmetric out-of-plane modes.

The Deep Orange program immerses automotive engineering students into the world of an OEM as part of their 2-year graduate education. In support of developing the program’s seventh vehicle concept, the students studied the sponsoring brand essence, conducted market research, and made a heuristic assessment of competitor vehicles. The upfront research lead to the definition of target customers and setting vehicle level targets that were broken down into requirements to develop various vehicle sub-systems. The powertrain team was challenged to develop a scalable propulsion concept enabled by a common vehicle architecture that allowed future customers to select (at the point of purchase) among various levels of electrification best suiting their needs and personal desires. Four different configurations were identified and developed: all-electric, two plug-in hybrid electric configurations, and an internal combustion engine only.

NASA's future missions to explore the solar system will be long-duration missions and could last years at a time. Human life support systems required for these missions must operate with very high reliability for long periods of time and must be highly regenerative, requiring minimum resupply. Such life support systems will make use of combining higher plants, microorganisms, and physicochemical processes to recycle air and water, process wastes, and produce food. Development of regenerative life support systems will be a pivotal capability for missions to the moon and Mars. One key step in the development process for these systems is the establishment of a human-rated test facility specifically tailored for evaluation of closed, regenerative life support systems--one in which long-duration testing can take place involving human test crews.

The automotive thermal management system is responsible for maintaining engine and passenger compartment temperatures, which promote normal combustion events and passenger comfort. This system traditionally circulates a water ethylene glycol mixture through the engine block using a belt-driven water pump, wax pellet thermostat valve, radiator with electric fan, and heater core. Although vehicle cooling system performance has been reliable and acceptable for many decades, advances in mechatronics have permitted upgrades to powertrain and chassis components. In a similar spirit, the introduction of a variable speed electric water pump and servo-motor thermostat valve allows ECU-based thermal control. This paper examines the integration of an electric water pump and intelligent thermostat valve to satisfy the engine's basic cooling requirements, minimize combustion chamber fluctuations due to engine speed changes, and permit quick heating of a cold block.

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.

Development of new air revitalization system (ARS) technology can initially be performed in a subscale laboratory environment, but in order to advance the maturity level, the technology must be tested in an end-to-end integrated environment. The Air Revitalization Technology Evaluation Facility (ARTEF) at the NASA Johnson Space Center (JSC) serves as a ground test bed for evaluating emerging ARS technologies in an environment representative of spacecraft atmospheres. At the center of the ARTEF is a hypobaric chamber which serves as a sealed atmospheric chamber for closed loop testing. A Human Metabolic Simulator (HMS) was custom-built to simulate the consumption of oxygen, and production of carbon dioxide, moisture and heat by up to eight persons. A variety of gas analyzers and dew point sensors are used to monitor the chamber atmosphere and the process flow upstream and downstream of a test article. A robust vacuum system is needed to simulate the vacuum of space.

Future NASA manned missions to the moon and Mars will require development of robust regenerative life support system technologies which offer high reliability and minimal resupply. To support the development of such systems, early ground-based test facilities will be required to demonstrate integrated, long-duration performance of candidate regenerative air revitalization, water recovery, and thermal management systems. The advanced life support Systems Integration Research Facility (SIRF) is one such test facility currently being developed at NASA's Johnson Space Center (JSC). The SIRF, when completed, will accommodate unmanned and subsequently manned integrated testing of advanced regenerative life support technologies at ambient and reduced atmospheric pressures.

Debris and particulate filtration problems have been persistent during flights on the Space Shuttle Orbiter since STS-6. Analysis of the Orbiter Environmental and Life Support System (ECLSS) indicated that both the volumetric flows and velocities were essentially designed for ventilation, heat removal, and gas blending with minimal consideration for debris removal. The baseline Orbiter filtration system consisted of a single 300 micron filter at the inlet of the cabin fan primarily to protect the cabin fan hardware. This filter was increased to 70 microns and additional filters added after some hardware failures occurred. However, these changes did not clean the environment as expected. An evaluation of the size and type of debris in the cabin air determined that the debris is able to “short-circuit” the cabin filtration system and remains in the cabin air causing the crew discomfort.

Experimental evaluations were made of single- and double-pass heat exchangers for automotive application. The study was concerned primarily with the effect of the working parameters, air and water mass flow rates and the inlet water temperature, on the average and local heat transfer coefficients. An automotive radiator having two water-side passes was fabricated and tested. The experimental results were compared with those for a single-pass unit. The study showed that the overall coefficient of heat transfer of the single-pass radiator was higher than that of the double-pass radiator.

An evaporative heat sink has been designed and built by AlliedSignal for NASA's Johnson Space Center. The unit is a demonstrator of a primary heat exchanger for NASA's prototype Crew Return Vehicle (CRV), designated the X-38. The primary heat exchanger is responsible for rejecting the heat produced by both the flight crew and the avionics. Spacecraft evaporative heat sinks utilize space vacuum as a resource to control the vapor pressure of a liquid. For the X-38, water has been chosen as the heat transport fluid. A portion of this coolant flow is bled off for use as the evaporant. At sufficiently low pressures, the water can be made to boil at temperatures approaching its freezing point. Heat transferred to liquid water in this state will cause the liquid to evaporate, thus creating a heat sink for the spacecraft's coolant loop. The CRV mission requires the heat exchanger to be compact and low in mass.

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.