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The applications of unmanned aerial vehicles (UAV) are growing exponentially with advances in hybrid powertrain architecture design tools. The thermal management system (TMS) as an integral part of the powertrain architecture greatly affects the system performance of aerial vehicles. In this study, a comparative analysis of two types of thermal management technologies for a UAV with a series-hybrid powertrain architecture was performed. Conventional TMS based on single-phase (no phase change) cooling technologies using air and liquid (e.g., antifreeze water mixture and oil) as heat transfer fluid has been commonly used because of simple design and operation, although it is considered to be inefficient and bulky. As advanced designs, phase change-based TMS is being slowly adopted although it promises superior cooling capabilities.

The thermal management of traction batteries for electric-drive vehicles greatly affects the battery performance and life time. It is important that the maximum cell temperature is maintained below the allowable maximum temperature and the temperature difference in the battery system is as small as possible. A spatial-resolution lumped-capacitance thermal model was developed to predict the battery temperatures of core, surface and averaged for high cell Biot numbers (Bi ≻ 0.1) to which the classical lumped-capacitance model is inapplicable because of the significant spatial distribution of the cell temperature. The results of the spatial-resolution lumped-capacitance model were compared with the numerical results using ANSYS, which is referred as a benchmark solution.

Thermal characterization was performed on a vapor compression heat pump using a novel, hybrid two phase loop design. Previous work on this technology has demonstrated its ability to provide passive phase separation and flow control based on capillary action. This provides high quality vapor to the compressor without relying on gravity-based phase separation or other active devices. This paper describes the subsequent work done to characterize evaporator performance under various startup scenarios, tilt angles, and heat loads. The use of a thermal expansion valve as a method to regulate operation was investigated. The effect of past history of use on startup behavior was also studied. Testing under various tilt angles showed evaporator performance to be affected by both adverse and favorable tilts for the given compressor. And depending on the distribution of liquid in the system upon startup, markedly different performance can result for the same system settings and heat loads.

Army's next generation vehicles require more electric and electronic devices with increasing power density for improved multi-functionality. The increasing waste heat from these devices will present great challenges to the capabilities of conventional air/liquid cooling systems in cooling multiple, high heat flux sources dispersed over the entire vehicle. In this paper, a high performance hybrid loop thermal bus technology for vehicle thermal management is presented. The technology combines the robust operation of pumped two-phase flow cooling with the simplicity of capillary flow management. The test results show the hybrid loop thermal bus can manage multiple high heat flux heat sources during the startup and transient heat input operation with no flow control.

Li-Ion battery is attractive for HEVs and FCEVs because of its high power density and lack of memory effect. However, high battery temperatures during operation result in a short battery lifespan and degraded performance. To address this issue, battery manufacturers and OEMs have used different pre-set cooling strategies. Unlike the pre-set cooling strategy this thermal model forecasts battery temperatures, allows a better usage of the battery system, responds to battery power demand and maintains battery temperature limits. This paper discusses the real-time control of the battery cooling including battery stress analysis. The authors present a dynamic thermal model for the Li-Ion battery system using the finite-volume method and discuss transient battery thermal characteristics and real-time battery cooling control under various battery duty cycles. Validation results of the model are presented in this paper.

This paper investigates the use of carrier-phase differential GPS (CDGPS) for race car applications. In particular, experimental results are presented to demonstrate the use of CDGPS to accurately measure several key parameters of a test vehicle, including the inertial velocity, side-slip, and its precise location. This data is useful as a driver's coaching tool because it can be used to determine what the driver is doing and when, and also show precisely where these actions are being performed on the track. While CDGPS offers the potential of very precise position estimation, even a temporary blockage to the NAVSTAR constellation (e.g., by trees/bridges) means that the measurement biases must be re-acquired before a good solution can be obtained. Various solutions to this problem have been investigated, but each presents new difficulties and/or requires more expensive equipment.

While a Ni-MH battery has good performance properties, such as a high power density and no memory effect, it needs a powerful thermal management system to maintain within the required narrow thermal operating range for the 42V HEV applications. Inappropriate battery temperatures result in degradation of the battery performance and life. For the battery cooling system, air is blown into the battery pack. The exhaust is then vented outside due to potential safety issues with battery emissions. This cooling strategy can significantly impact fuel economy and cabin climate control. This is particularly true when the battery is experiencing frequent charge and discharge of high-depths in extreme hot or cold weather conditions. To optimize performance and life of HEV traction batteries, the battery cooling design must keep the battery operation temperature below a maximum value and uniform across the battery cells.

Increased cooling demands in Hybrid Electric Vehicles (HEVs), compactness of engine compartment, and the additional hardware under the hood make it challenging to provide an effective cooling system that has least impact on fuel economy, cabin comfort and cost. Typically HEVs tend to have a dedicated cooling system for the hybrid components due to the different coolant temperatures and coolant flow rates. The additional cooling system doubles the hardware, maintenance, cost, weight and affects vehicle fuel economy. In addition to the cooling hardware, there are several harnesses and electronics that need air cooling under the hood. This additional hardware causes airflow restriction affecting the convective heat transfer under the hood. It also affects the radiation heat transfer due to the proximity of hardware close to the major heat sources like the exhaust pipe.