Browse Topic: Cold weather
ABSTRACT The department of defense currently uses a number of models of vehicle start batteries with the “6T” form factor. These batteries are typically found in almost every vehicle in the DOD fleet and other systems that require 28VDC power. The use of power and energy on the battlefield is significantly changing and the Warfighter now requires a “start” battery that is used for more than just starting, lighting and ignition (SLI) for the vehicle. Lithium ion battery technologies are showing great promise in addressing these challenges by providing higher power capability for extended silent watch, battery monitoring and extended cycle life. One concern, however, is their ability to operate at low temperatures. One of the most challenging aspects of battery use in military applications is their operation at extreme high and low temperatures. These wide temperature swings can potentially have a dramatic effect on cycle life and performance. One significant concern, especially for
NASA’s Johnson Space Center is offering an innovative freeze-resistant hydration system for licensing. The technology substantially improves on existing hydration systems because it prevents water from freezing in the tubing, container, and mouthpiece, even in the harshest conditions on Earth
Many owners of electric vehicles worry about how effective their battery will be in very cold weather. Now a new battery chemistry may have solved that problem
Considerable amounts of water accumulate in aircraft fuel tanks due to condensation of vapor during flight or directly during fueling with contaminated kerosene. This can result in a misreading of the fuel meters. In certain aircraft types, ice blocks resulting from the low temperatures at high altitude flights or in winter time can even interfere with the nozzles of the fuel supply pipes from the tanks to the engines. Therefore, as part of the maintenance operations, water has to be drained in certain intervals ensuring that no remaining ice is present. In the absence of an established method for determining residual ice blocks inside, the aircraft operator has to wait long enough, in some cases too long, to start the draining procedure, leading potentially to an unnecessary long ground time. A promising technology to determine melting ice uses acoustic signals generated and emitted during ice melting. With acoustic emissions, mainly situated in the ultrasonic frequency range, a very
This SAE Aerospace Recommended Practice (ARP) is written to establish tire removal criteria of on-wing civil aircraft tires only. This document is primarily intended for use with commercial aircraft, but may be used on other categories of civil aircraft, as applicable. The criteria are harmonized with the care and service manuals (CSMs) of the tire manufacturers for both radial and bias tires
This SAE Aerospace Recommended Practice (ARP) covers the requirements for a Stationary Runway Weather Information System (referred to as the system) to monitor the surface conditions of airfield operational areas to ensure safer ground operations of aircraft. The system provides (1) temperature and condition information of runway, taxiway, and ramp pavements and (2) atmospheric weather conditions that assist airport personnel to maintain safer and more efficient airport operations. The system can be either a wired system or a wireless system
With the growing demand in passenger comfort and enhanced safety and high competitiveness in the automotive segment, automotive manufacturers are keen to launch the product flawlessly within short period of time. In that regard one of the areas related to safety of passengers which is windshield deicing, requires lot of attention and to be developed and certified well before the product launch. Computational fluid dynamics (CFD) helps in this regard to come up quickly with a feasible design solution. But with the conventional method of doing deicing requires lot of time and high cell count. Hence there is a requirement of developing a methodology which will shorten the simulation time and thus leading to shorter development time. One such development took place is in the multiphase models in CFD. The present study focuses in introducing a novel methodology for predicting the transient deicing pattern in an automotive windshield. Simcenter STAR-CCM+ version 2021.2.1 was used for the
It is widely known that different factors, such as cold properties of a fuel as well as a vehicle design, affect the cold operability limit of vehicles. In this study, the aim was to get a better understanding of the properties of modern Light Duty Diesel (LDD) vehicles (2014-2020) that define their cold operability temperature limit. Moreover, the aim was to find out what a responsible fuel producer can do, in addition to providing a proper fuel that meets the specification, to ensure that a vehicle stays operable at cold temperatures. Similar study was done 10 years ago by Neste with the LDD vehicles of that time [1]. Therefore there was a need to update the info to concern the modern LDD vehicles. In this study the operability limit difference between the worst and the best operating LDD vehicle was >10°C (nbr of LDD vehicles = 5) with the same fuel. The limits were determined in a cold chamber using a chassis dynamometer. This operability variance indicates a significant effect of
As the global automotive industry makes a critical transition from the traditional ICEVs (Internal Combustion Engine Vehicles) to EVs (Electric Vehicles), it faces two conflicting technological challenges: 1) range degradation in cold weather conditions and 2) reducing time to thermal comfort in winter driving in absence of waste heat from the IC engine. Next to the EV drivetrain, the HVAC (Heating Ventilation and Air Conditioning) system is the highest consumer of electric power in the vehicle. To get the occupants to a thermally comfortable state as quickly and efficiently as possible, automotive OEMs (Original Equipment Manufacturers) are exploring microclimate systems that involve localized heating and cooling. Unlike the central HVAC system, localized heating and cooling devices such as climate-controlled seats, steering wheel heaters, neck warmers, etc. directly condition the occupant rather than conditioning the entire cabin environment to provide thermal comfort to the occupant
Proton exchange membrane fuel cell (PEMFC) system is considered as one of the most popular power sources because of its high energy density, fast dynamic response and zero pollution. However, the start-up at low temperature (e.g. - 30 °C) is still a major challenge for its wide application due to water freezing in Membrane Electrode Assembly (MEA). In this paper, a cold start test process in an environment cabin with auxiliary heat was carried out for a full power automotive PEMFC system, including normal operation, shutdown purge and cold start processes analysis from -30°C. Rated power of this stack is 100kW at the current density of 1.4A/cm2 and relevant maximum output power can reach to 120kW. In order to reduce the damage of high potential to MEA, on-load purge with a current of 30A is conducted to removing extra water in stack for improving cold start ability. Based on corresponding control strategy, cold start was realized successfully within 110s. Low temperature not only
Proton exchange membrane fuel cell has received extensive attention from different industries due to its advantages such as high efficiency, high energy density, and clean emissions. However, performance at low temperature is still one of the key factors that restricted its wide commercialization. To study the internal water state of the fuel cell at low temperature and verify different cold-start strategies, a fuel cell test platform that can simulate a low-temperature environment is needed. As the power of the stack grows, the impact of the size of a membrane and the impact of the number of single cells can’t be negligible. Meanwhile, the mutual influence between adjacent single cells at low temperatures is also worth studying. However, a test platform for high-power fuel cell stack with the ability to simulate a sub-freezing temperature is currently lacking. Thus, in this work, a 10kW-class fuel cell test platform is designed. This test platform includes a gas supply and exhaust
We love the warm rays of the summer sun, enjoy cooling off with a cold drink or a refreshing dip in the pool. We appreciate the warm touch of another person, enjoy a hot tea or warming fireplace in winter. We feel temperature, but we cannot ‘see it’ with our eyes
Thermal comfort in the vehicle cabin environment is an important factor for passengers of both internal combustion engines and electric vehicles. Heating, Ventilation and Air Conditioning (HVAC) is a critical system for electric vehicles (EVs) as it is the second most power consumer after electric motor. Novel solutions dedicated to EV, including thermoelectric air conditioning (AC) modules, vapor compression refrigeration (VCR), cycle positive temperature coefficient (PTC) heater as well as heat pumps (HP), are being investigated to maintain a stable and comfortable interior environment under hot and cold weather conditions. At present, the mostly dominated automotive AC systems are those using R134a refrigerant characterized by high global warming potential. Therefore, an innovative and ecofriendly AC system design still must be developed to supply sufficient cooling or heating capacity while minimizing the influence of the AC system on driving ranges and environmental performance. A
It is particularly easy to get tunnel vision as a domain expert, and focus only on the improvements one could provide in their area of expertise. To make matters worse, many Original Equipment Manufacturers (OEMs) are silo-ed by domain of expertise, unconsciously promoting this single mindedness in design. Unfortunately, the successful and profitable development of a vehicle is dependent on the delicate balance of performance across many domains, involving multiple physics and departments. Taking for instance the design of a Heating, Ventilation & Air Conditioning (HVAC) system, the device’s primary function is to control the climate system in vehicle cabins, and more importantly to make sure that critical areas on the windshield can be defrosted in cold weather conditions within regulation time. With the advent of electric and autonomous vehicles, further importance is now also placed on the energy efficiency of the HVAC, and its noise. During the development of the defrost mode of an
This document describes a standard method for measuring the viscosity of thickened (AMS1428) Type II/III/IV Aircraft Deicing/Anti-icing Fluids. The determination of viscosity for a Non-Newtonian fluid is very sensitive to shear and differences in sample chamber geometry. Even slight differences can have a large effect on measurement results. The test parameters and associated error for this standard are applicable to the Brookfield LV viscometer. A Brookfield LV or equivalent viscometer shall be used. To be considered equivalent, an alternate viscometer must demonstrate statistically equivalent performance, i.e., accuracy and precision when testing thickened (AMS1428) fluids using the same test parameters and conditions.Test parameters and conditions outside of the ranges described within this standard may be used only if they meet minimum limits for precision and accuracy established for the Brookfield LV viscometer. To compare viscosities, the same test parameters and conditions
This SAE Standard applies to self-propelled, rider operated sweepers and scrubbers as defined in SAE J2130 with maximum machine level surface speeds up to 32 km/h. Machines capable of speeds equal to and greater than 32 km/h are not covered by this document
This paper presents experimental results that validate eco-driving and eco-heating strategies developed for connected and automated vehicles (CAVs). By exploiting vehicle-to-infrastructure (V2I) communications, traffic signal timing, and queue length estimations, optimized and smoothed speed profiles for the ego-vehicle are generated to reduce energy consumption. Next, the planned eco-trajectories are incorporated into a real-time predictive optimization framework that coordinates the cabin thermal load (in cold weather) with the speed preview, i.e., eco-heating. To enable eco-heating, the engine coolant (as the only heat source for cabin heating) and the cabin air are leveraged as two thermal energy storages. Our eco-heating strategy stores thermal energy in the engine coolant and cabin air while the vehicle is driving at high speeds, and releases the stored energy slowly during the vehicle stops for cabin heating without forcing the engine to idle to provide the heating source. To
The purpose of this SAE Aerospace Standard is to provide guidelines for the components and configurations that define the research and commercial versions of the Weather Support to Deicing Decision Making (WSDDM) winter weather nowcasting system
Light is the primary stimulus for regulating circadian rhythms, seasonal cycles, and neuroendocrine responses in many species including humans. During the past 20 years, studies have tested the use of light for treating fall and winter depression (Seasonal Affective Disorder or SAD), non-seasonal depression, sleep disorders, menstrual dysfunction, and eating disorders. In addition, investigators are exploring the use of light for reentraining human circadian physiology relative to the challenge of shift work or intercontinental air travel
This SAE Aerospace Information Report (AIR) covers, and is restricted to, selecting appropriate applications for electric powered ground support equipment (GSE) at airports
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