Modernized Navy Fan-Coil Assembly

Navy SBIR 22.1 - Topic N221-054
NAVSEA - Naval Sea Systems Command
Opens: January 12, 2022 - Closes: February 10, 2022 (12:00pm est)

N221-054 TITLE: Modernized Navy Fan-Coil Assembly

OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR)

TECHNOLOGY AREA(S): Ground / Sea Vehicles

OBJECTIVE: Develop and demonstrate durable, long-life, modernized Fan-Coil Assembly (FCA), while reducing required motor horsepower, lowering noise levels, using less chilled water flow than legacy FCA units, maintaining or improving weight/volume requirements, providing greater standardization, and lowering overall life cycle as well as maintenance costs.

DESCRIPTION: Fan-Coil Assemblies (FCAs) are typically used in recirculation systems using modular design, which allows for quick and easy installations. However, FCAs on Navy ships have changed little over the last 60 years. These legacy systems are heavy, energy inefficient, and operate at a single fan speed using a V-belt-driven fan. This has the unintended consequence of causing the temperature in the supplied spaces to be either too hot or too cold, and requires the system to switch on and off intermittently during operation, thus cooling and heating the same air, and wasting energy.

This SBIR topic will seek to develop compact, light, and efficient, drive systems that can react smoothly to temperature variations. The proposed solution will develop a new series of FCAs that are efficient, acoustically compliant, aerodynamically-optimized, lightweight, and reduced size, all of which will be necessary for the next-generation Navy HVAC system. The new design will incorporate improvements that result in a reduction in the required fan motor horsepower by 30% from the legacy units per MIL-PRF-23798D, Performance Specification, Air Conditioner, Fan-Coil Assembly [Ref 1], compliance with noise levels in accordance with MIL-STD-1474D, Change Notice 1 - Change Notice 1, Noise Limits [Ref 2], and reduced chill-water flow per developing Navy requirements.

The fan shall be designed for continuous operation, have a minimum efficiency of 80 percent, and be equipped with variable speed controls meant to replace the belt-driven system on legacy FCA units. The Variable-Speed Drive (VSD) controller will be in accordance with MIL-PRF-32168, PERFORMANCE SPECIFICATION: VARIABLE SPEED DRIVE SYSTEM FOR INDUCTION AND SYNCHRONOUS [Ref 3]. The targeted water-side pressure drop is 6 lb/in2 across the heat exchanger, with a maximum of 10 lb/in2. The design conditions of the entering air temperatures will be assumed to be 80°F dry bulb and 67°F wet bulb temperature, and under ambient temperatures between 40 °F and 95 °F. Design conditions for the entering chill water temperature is 43°F, supplied at 2.1-2.3 gallons per minute per cooling ton, reduced from legacy design specifications to meet new equipment performance.

The FCA shall be a complete assembly, that contains all components necessary for providing cooling and air recirculation required to satisfy compartment environmental design conditions. Each unit shall consist of a fan with a variable speed motor, a variable speed controller, air filter, thermal and acoustic insulation, a common open protocol control system, and a chilled water cooling coil. The performance of each unit will meet or exceed the performance requirements of legacy FCA units per MIL-PRF-23798D [Ref 1] and be tested to address shock, vibration, electromagnetic interference, performance testing, airborne testing, structure borne vibration testing, motor testing, and electrical power interface testing. The awardee will be responsible for the performance of all examinations and tests. The Government will reserve the right to perform any of the tests which, upon determination and capability of awardee, are deemed necessary to ensure the FCAs conform to prescribed requirements. Test plans will be developed during Phase I, with testing to take place during Phase II.

Fan-Coil HVAC systems similar to legacy Navy FCAs are commercially available, and the operating principles are well understood within the HVAC industry. However, a complete FCA system package that meets the performance requirements outlined by the existing system performance specification, MIL-PRF-23798D, while also integrating a Variable-Speed Drive (VSD) fan controller meeting MIL-PRF-32168, has yet to be realized. This topic seeks to leverage industry-developed technologies to develop a family of modernized FCAs that improve upon the legacy systems.

PHASE I: Develop an innovative concept for the next generation of naval FCAs by meeting requirements above and targeting the performance specifications for the FCA Size 25 per MIL-PRF-23798D. Evaluate the feasibility of concepts through analytical modeling. Define strategies and technologies related to cooling coil performance, optimized air-side aerodynamic performance, reduced air-borne noise, and improved component reliability. Determine the size and weight improvement expectations over existing components. Determine coefficient of performance for cooling and heating applications as well as identify water-side pressure drop and fan performance expectations. Identify risks and mitigation measures, as applicable. The Phase I Option, if exercised, will include the initial design specifications and a capabilities description to build and test a prototype solution in Phase II. This will also include the development of test plans to identify all test procedures, test facilities, sequence of test procedures, component set-up, instrumentation and data to be collected. The tests included in the Phase I test plans will be as follows:

  • Motor tests
  • Permeability tests
  • Leakage tests
  • Electrical Power Interface test
  • Communication Interface
  • Performance tests
  • Airborne noise tests
  • Electromagnetic Interference (EMI)
  • Structure borne Vibrations tests
  • Shock tests
  • Maintainability demonstration

PHASE II: Design and deliver the prototype, full-scale, next generation Fan-Coil Assembly (FCA) Size 25 (largest size) unit (151,300 Btu/h, 3080 SCFM). Performance data shall be collected at a variety of flow rates (both air and water), air temperatures/humidity, and water temperatures. Air-borne and structure-borne noise testing shall be conducted. Validate and expand analytic models developed in Phase I. Investigate the scalability of design and identify commonality efforts. Refine calculation and estimates provided in Phase I. This first-article prototype unit must also meet Navy unique requirements, such as shock and vibration in accordance with -S-901 - Shock Tests, H.I. (High-Impact) Shipboard Machinery, Equipment, and Systems, Requirements for [Ref 4] and MIL-STD-167-1 - Mechanical Vibrations of Shipboard Equipment (Type 1 - Environmental and Type II - Internally Excited) [Ref 5], as well as Electromagnetic Interference in accordance with MIL-STD-461 - Requirements for the Control of Electromagnetic Interference Emissions and Susceptibility Requirements for Characteristics of Subsystems and Equipment [Ref 6]. The final product will be a modernized first-article Size 25 Fan-Coil Assembly (FCA) which meets the test requirements established in the test plans developed during Phase I.

PHASE III DUAL USE APPLICATIONS: Following the successful design of the modernized FCA 25 and the satisfactory results of Phase II, the remainder of the series will be designed based on the qualified design and the company will assist the Navy in transitioning the technology for Navy use. Scale the results to design and develop the new series of modernized FCAs. To qualify the designs and collect data for future-program use, each size of the new FCA series will be installed on an operating Navy vessel, or tested in such a way to qualify the unit(s) design. Comparisons of existing systems will be made so the energy usage of the modernized FCAs can be directly compared with similar legacy unit(s) that will operate under the similar shipboard parameters. Each unit’s energy usage, system reliability, and maintenance will be assessed to inform the comparison. Demonstrate successful performance of the new series units to meet and/or exceed all specified modernized FCA requirements. It is envisioned that this development work for the remainder of the series will be covered by the program office(s) electing to integrate the modernized FCA line into their ship program.

Demonstrate large-sale manufacturability of the full series of FCAs, as well as provide maintainability support through operational and maintenance documentation. Develop the manufacturing plan, based on Navy-driven need for the units, and provide assistance with system integration as needed during Navy design efforts.

The development of the modernized FCA is envisioned to primarily benefit the Large Surface Combatant (DDG(X)) program, as well as future Navy ship programs. However, with much of the development carried out during the preceding Phases, the technology innovations developed through this project could be leveraged for potential back-fit modernization applications across the Surface Fleet. Current in-service ships in the Surface Fleet carry a total of between 30 and 50 total legacy FCAs, distributed among the different sizes in the family. This represents an opportunity to encourage commonality and form-fit-function design intent for the modernized version to help make back-fit more feasible.

Additionally, the innovation addressed in the project could potentially allow the company to expand its advantage in the industrial HVAC market. By designing the modernized FCAs with aerodynamically optimized air flow and airborne noise requirements, those innovations could inform the awardee’s commercial product line to enhance air-side efficiency and reduce airborne noise, while meeting the unique cooling requirements for an industrial or residential setting.


  2. "MIL-STD-1474D, Change Notice 1 - Change Notice 1, Noise Limits."
  4. "MIL-DTL-901E, Detail Specification: Shock Tests, H.I. (High-Impact) Shipboard Machinery, Equipment, and Systems, Requirements for (20-JUN-2017) [SUPERSEDING MIL-S-901D]."
  5. "MIL-STD-167-1 - Mechanical Vibrations of Shipboard Equipment (Type 1 - Environmental and Type II - Internally Excited)."
  6. "MIL-STD-461 - Requirements for the Control of Electromagnetic Interference Emissions and Susceptibility Requirements for Characteristics of Subsystems and Equipment."
  7. "NAVSEA Releases Naval Power and Energy Systems Technology Development Roadmap." Team Ships Public Affairs, Naval Sea Systems Command, June 2019. Roadmap document PDF:
  8. Frank, Matthew V.; Helmick, Dick. 21st Century HVAC System for Future Naval Surface Combatants - Concept Development Report. NSWCCD-98-TR–2007. Naval Surface Warfare Center Carderock Division. September 2007.

KEYWORDS: V-belt fan driven; Navy Ventilation and Air Conditioning; Heating, Ventilation, and Cooling; HVAC; cooling coils; Variable speed; Fan Coil Assembly; Thermal Management


The Navy Topic above is an "unofficial" copy from the overall DoD 22.1 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its 22.1 SBIR BAA pre-release on December 1, 2021, which opens to receive proposals on January 12, 2022, and closes February 10, 2022 (12:00pm est).

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