TECHNOLOGY AREAS: Ground/Sea Vehicles

ACQUISITION PROGRAM: NAVSEA 05Z4, PEO SHIPS

OBJECTIVE: Develop advanced concepts for cooling coils in order to reduce the size and weight of shipboard cooling coils while improving performance and lowering overall life cycle costs. Approaches to eliminate moisture carryover at face velocities of 1000 feet per minute shall be identified.

DESCRIPTION: Thermal Management is a critical requirement for future warships with electronic propulsion, weapon, and sensor systems. Evolving battle-space doctrine, emphasizing operations in the littoral, is resulting in the upward revision of the traditional design weather and seawater temperatures. This is having a substantial impact on the thermal load of ship designs in the acquisition cycle. The HVAC system is critical to the functionality of the ship�s combat and damage control systems, in addition to ensuring the comfort and health of the crew. As such, the HVAC system has changed little over the past 50 years leading to simplistic installation of larger and heavier systems to meet increasing thermal loads. To meet this challenge, HVAC concepts to provide flexible thermal management at the ship level while providing a comfortable ship environment, rapid and redundant damage control capability, energy efficiency, reduced size and weight, and reduced manning are being explored.

Today�s cooling coils are designed to provide cooling capacities from 0.75 to 20 tons of cooling. Dry weights of these components range from 40 to 140 pounds per ton of cooling with volumes of 1 to 2 cubic feet per ton of cooling. Performance is based on the availability of 3.6 gallons per minute per cooling ton of 45 �F chilled water. Face velocity is limited to 500 feet per minute to eliminate moisture carryover. Air-side pressure drops are less than an inch of water across the cooling coil. Innovative research is sought to produce next generation compact and lightweight cooling coils with enhanced heat transfer surfaces operating at face velocities in excess of 1000 feet per minute. Key issues to be resolved are eliminating moisture carryover at those velocities by incorporating passive separation devices at the exit of the coil or advanced coating technologies on the fin surface to promote rapid drainage of the condensed water from the finned surface or other innovative passive concepts.

PHASE I: Develop advanced concepts for cooling coils with face velocities of 1000 feet per minute (minimum) using half the chilled water flow (1.8 gallon per minute per ton of cooling) and 40 �F chilled water. Determine the size and weight reduction over existing components. Evaluate the feasibility of concepts through analytical modeling. Develop a performance testing plan for Phase II including identification of risks.

PHASE II: Design and manufacture a full scale cooling coil of a selected size (0.75 to 20-ton cooling capacity). Performance data shall be collected at a variety of flow rates (both air and chilled water) air temperatures and humidity, and water temperatures. Validate analytic models developed in Phase I and evaluate scalability of design.

PHASE III: Design and develop the next series of compact, high velocity cooling coils using the knowledge gained during Phases I and II. This series of cooling coils must meet Navy unique requirements, e.g. shock and vibration.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Advanced cooling coils developed here would be suitable for use in commercial and home HVAC systems.

REFERENCES:
1. MIL-PRF-2939G, 20 July 2001 � Cooling Coils, Air, Duct Type and Gravity Type, Naval Shipboard Environmental Control System.

2. Air Conditioning and Refrigeration Institute, Standard 410 � Forced Circulation Air-Cooling and Air Heating Coils.

KEYWORDS: thermal management; cooling coils; heating, ventilation and air conditioning (HVAC)

** TOPIC AUTHOR (TPOC) **

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