N152-099   TITLE:  Cooled BusWork for Shipboard Distribution and Energy Storage

TECHNOLOGY AREAS:  Electronics, Weapons

ACQUISITION PROGRAM:  PMS 320, Electric Ships Office; POM-15 Multi-function Energy Storage Module

OBJECTIVE:  Develop an innovative modular bus bar cooling system for energy storage with high rate heat removal that leverages the thermal mass and conductivity of bussing systems.

DESCRIPTION:  Improvements in the manufacturing of power density, power quality, and efficiency in power and energy management and control are needed by the Navy to meet power and energy demands and allow for future mission growth. The Navy is seeking to foster the development of common, affordable electrical components and systems that could have broad application to ships. Electrochemical storage (battery) cells have designs which do not lend themselves to effective thermal management. For planar and cylindrical cells, the axes which offer the maximum surface area are those which offer the greatest thermal resistance. This is due to the nature of the design, which is effectively a layered structure of polymer, metal and some thin chemical coatings, all wetted in an organic electrolyte. Developing a cooling system at the in-plane direction of the conductors may result in better thermal regulation from the use of tab and bussing connections, as well as vents, sensors, and others which are often tied to the cell-ends, particularly by leveraging thermal regulation internal to the cells under high rate transient conditions (ref #1). Cooling of the out-of-plane surfaces would likely still be used in combination with the innovative new system.  The objective of this effort is to optimize use of the busbar for cooling, given its intimate contact with the conductors internal to the cell, as well as its mass and necessity to be routed throughout battery modules for electrical conductivity (ref #2). Typically, batteries are electrically connected to one another through busbars or similar buswork. And, typically, the main purpose of the busbars is to conduct current with minimal resistance. However, in this work, an advanced busbar for innovative thermal control and enhanced electrical performance is desired. The system will have to include the capability to circulate a cooling medium for optimized thermal control. Buswork developed should allow for integration on any battery module, thus the technologies proposed should be scalable from small 10Ah type cells through 60+Ah large format cell designs. Proposed approaches can be passively or actively operational and must consider the flow of cooling media and electrons in terms of media selection, system continuity, and failure modes. Technologies developed for this specific application will also be explored for applicability to electric power distribution buswork, such as those used in switchboards. Technologies proposed under this effort should not contain precious or hazardous materials, nor require significant deviation from a typical battery system design (such as cells placed in a geometric array and connected in series). It is optimal for these devices to operate such that chilled water is not required, though glycol/water mixtures can be assumed to be available at 40 degrees C, with sufficient flow available to meet mission needs. Ambient spaces should be assumed to be up to 60 degrees C and battery maximum operational temperatures should also be assumed to be 60 degrees C. In order to maintain density of the energy storage devices, the proposed approaches should not increase the cell length over 50% beyond the commonly accepted value for bussing for a specific ampacity associated with the cell’s maximum rating. If a special cooling fluid is to be utilized, the interface to shipboard cooling fluid should be considered, along with the impact on efficiency and device/system density and packaging size. The end intent is to utilize this design as part of a tightlypackaged battery system, complete with thermal management, monitoring, fire suppression and requisite safety devices; the innovative approach proposed under this solicitation would serve as the connectivity between cells in battery modules of different sizes and ratings. 

Proposed buswork concepts should meet the following thresholds: 

•        Deliverable Design Characteristics Value 

•        Chemistry Li-ion 

•        Cell Capacity: 20-30Ah, scalable 

•        Cell Form Factor: Cylindrical or Prismatic (pouch or hard cell) 

•        Cell Case Polarity: Case positive, neutral or negative 

•        Operational Rate: Continuous >15 C-rate 

•        Design: Modular; combine in series via rack mount to obtain system interface 

•        Module Packaging: Metal or Polymeric Exterior 

•        Module Voltage: =48 VDC 

•        System Voltage: =1000 VDC 

•        Voltage Isolation: >2000 VDC 

•        Ambient Conditions: 0-60°C air 

•        Coolant Media: 0-35°C Seawater and/or 5-40°Coolant (50/50 Propylene Glycol/Water) 

•        Volumetric Penalty: =50% larger than appropriate copper busbar 

•        Management: Battery Monitoring System (BMS) capable of temperature and voltage cut-out 

•        Isolation: Contractor and Fuse 

•        Safety Process: NAVSEAINST 9310 

•        Shock*: MIL-S-901D 

•        Vibration*: MIL-STD-167-1A 

•        Transportability*: MIL-STD-810G 

* = Design to this attribute 

PHASE I:  The company will demonstrate the feasibility of the concept in meeting Navy needs for an innovative modular bus bar cooling system and will establish that the concept can be feasibly developed into a useful product for the Navy. The company will prove the concept of external, axial heat transfer inplane with the current flow and identify performance advantages. Proof of concept will be demonstrated on a small cell or cells, which can be cycled in a manner suitable to create sufficient internal heating, and compared to a control approach. The proof of concept should also be demonstrated on cycling cells or integrated into a battery versus a control of the same design.

PHASE II:  Based on the results of Phase I effort, the small business will develop a Phase II prototype for evaluation. The prototype will be evaluated to determine its capability in meeting the performance goals defined in Phase II Statement of Work (SoW) and the Navy need for improved thermal management, in this case, via an innovative modular bus bar cooling system for energy storage with high rate heat removal that leverages the thermal mass and conductivity of bussing systems. The company will demonstrate the cooling device to support an arrangement of cells at the 48V module level. The prototype design should provide no less than 10Ah (threshold), 30Ah (objective), and should show applicability to be utilized with various cell geometries and battery architectures. The company will deliver a minimum of five of these prototypes to the Navy for evaluation. The Company will perform detailed analysis to ensure materials are rugged and appropriate for Navy application. Environmental, shock, and vibration analysis will also be performed.

PHASE III:  The company will apply the knowledge gained in Phase II to build an advanced module, suitably packaged with 1000VDC strings of cooled batteries, including battery management system, and characterize its performance at high discharge rates as defined by Navy requirements. Working with the Navy and applicable Industry partners, demonstrate application with the bus bar cooling system to be implemented within shipboard and/or land-based test site to support energy storage or other applications. The company will support the Navy for test and validation to certify and qualify the system for Navy use. The company shall explore the potential to transfer the bus bar cooling system to other military and commercial systems (electric grid, electric vehicles). Market research and analysis shall identify the most promising technology areas and the company shall develop manufacturing plans to facilitate a smooth transition to the Navy.

REFERENCES:  

1.     Pesaran, Ahmad, Vlahinos, Andreas Stuart, Thomas “Cooling and Preheating of Batteries in Hybrid Electric Vehicles” The 6th ASME-JSME Thermal Engineering Joint Conference March 16-20, 2003. www.nrel.gov/transportation/energystorage/pdfs/jte_2003-633_sw_ap.pdf, Retrieved 5 November 2014

2.     “Measurement of anisotropic thermophysical properties of cylindrical Li-ion cells” Drake, S.J., Wetz,

D.A., Ostanek, J.K., Miller, S.P., Heinzel, J.M., Jain, A., Journal of Power Sources, volume 252, issue ,

year 2014, pp. 298 – 304. www.uta.edu/faculty/jaina/MTL/pubs/Drake-JPS2014.pdf, Retrieved 5 November 2014

KEYWORDS:  Thermal management of electrochemical storage systems; Battery; busbar; battery cooling; battery heat removal; energy storage

** TOPIC AUTHOR (TPOC) **

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