N251-003 TITLE: Amphibious Combat Vehicle Improved Heating Ventilation and Cooling (HVAC) System

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Human-Machine Interfaces

OBJECTIVE: Develop a heating, ventilation, and cooling (HVAC) system that meets the HVAC requirements for onboard personnel (Ref 1), functions within space, weight, and power (SWaP) limitations, has minimal impact on vehicle noise levels (Ref 2), and does not introduce a significant maintenance burden.

DESCRIPTION: The Amphibious Combat Vehicle (ACV) is an amphibious armored vehicle designed to transport Marines on land and in the water. The vehicle is closed during water and combat operations so outside air must be supplied from above the vehicle. There are several variants of the vehicle.

1. The Personnel variant (ACV-P) has a crew of 3, carries 13 Infantry Marines, and requires the most volume/quantity of fresh air from outside the vehicle.

2. The Command-and-Control variant (ACV-C) has a crew of 3 and accommodates, in the troop compartment, up to 7 command staff members who conduct command and control (C2) tasks that require computer, servers, and communication equipment that generate heat and must be kept within acceptable temperatures.

3. The 30mm gun variant (ACV-30) has a crew of 3, carries 8 Infantry Marines, and has a 30mm Mk. 44 Bushmaster II Automatic Cannon. The ACV-30 requires air filtration or other ways to avoid bringing noxious fumes into the vehicle.

4. The recovery variant (ACV-R) has a crew of 4, all of whom are from the Maintainer Military Occupational Specialty (MOS), and has craning, winching, and repair capabilities.

When operating, the ACV variants’ noise levels can exceed single hearing protection levels. Noise level testing indicates that the current Environmental Control System (ECS) is one of the main culprits for excessive noise levels in the cabin. The system must not prevent the ACV from meeting MIL-STD-1474 guidelines for hearing protection and have minimal impact on weight.

The ACV-P is required to supply 20 cubic feet per minute of fresh air per person (320 cfm) and maintain an interior temperature below 90 degrees F in ambient conditions up to 110 degrees F, with a 1,120 W/m2 solar radiation load, doors and hatches closed, and engine running (estimated to require ~55,000 BTUs of cooling). The ACV-C requires 20 cubic feet per minute of fresh air per person (200 cfm) and ~55,000 BTUs of cooling. The ACV-30 needs a filtration system that will not introduce noxious fumes into the cabin and will provide 20 cubic feet per minute of fresh air per person (220 cfm).

The current HVAC system does not properly cool the space per requirements in MIL-STD 1472H. There is large variability across workstations within the vehicle and even within a given workstation (temperature variability between head and feet locations). The HVAC is located on the left side of the vehicle approximately 1/3 of the way back in the troop compartment and has no duct system or other means to distribute conditioned air evenly through the compartment, especially to locations in the far corners of the vehicle.

The current system requires its refrigerant lines to be emptied and the refrigerant captured when the vehicle engine is removed. Engine removal occurs frequently which causes significant maintenance delays. When the engine is re-installed, the lines must be reconnected, a vacuum pulled, and the refrigerant refilled. This greatly increases the time required to remove and reinstall the engine for maintenance.

PHASE I: Review the vehicle drawings or models and conduct a site visit to study an ACV to determine technical feasibility of a single system to meet the requirements of all four variants. Develop a concept for a new HVAC system or modification of the current system design. Demonstrate compliance through a combination of modeling, analyses, and bench top demonstration.

In addition to the Phase I deliverables described in the BAA, the awardee is expected to deliver at least 1 in-process design review with meeting minutes, report on results of modeling and simulation, and an initial Phase II proposal.

PHASE II: Using results from Phase I, fabricate and validate a prototype. Demonstrate the prototype’s ability to meet the requirements in the Description. Evaluate the results of the demonstration and refine the design as necessary. Conduct on-vehicle testing in a relevant environment. Evaluate and compare the results to Marine Corps requirements. Prepare a Phase III development plan to transition the technology for Marine Corps use. Delivered a prototype at the end of Phase II.

PHASE III DUAL USE APPLICATIONS: On vehicle testing across different variants and refinement as a result of testing will be required. Production planning and partnerships should be created if necessary for production.

Other military applications potentially include use in combat vehicles used by other services and other countries. The developed technology could also potentially be used in commercial markets such as heavy construction and agricultural equipment, and possibly in the Recreational Vehicle (RV) market.

REFERENCES:

1. US MIL-STD 1472H, DESIGN CRITERIA STANDARD HUMAN ENGINEERING. https://www.dau.edu/cop/hsi/documents/milstd-1472h-design-criteria-standard-human-engineering

2. US MIL-STD 1474 MIL-STD-1474E, DEPARTMENT OF DEFENSE DESIGN CRITERIA STANDARD: NOISE LIMITS (15-APR-2015). http://everyspec.com/MIL-STD/MIL-STD-1400-1499/MIL-STD-1474E_52224/

3. "CO2 as a Refrigerant ." Mercedes Benz, June 2021. https://www.bing.com/ck/a?!&&p=129127754f9de7dbJmltdHM9MTcyNDk3NjAwMCZpZ3VpZD0xNDIwMGZiMC1iODY2LTZmNTUtMWMxYi0xYjY2Yjk5NzZlYTAmaW5zaWQ9NTIyNg&ptn=3&ver=2&hsh=3&fclid=14200fb0-b866-6f55-1c1b-1b66b9976ea0&psq=co2+air+conditioning+automotive&u=a1aHR0cHM6Ly9hdXRvbW90aXZldGVjaGluZm8uY29tL3dwLWNvbnRlbnQvdXBsb2Fkcy8yMDIxLzA2L0NPMi1hcy1hLVJlZnJpZ2VyYW50LWlzLUhhcHBlbmluZy5wZGY&ntb=1

 

KEYWORDS: Amphibious Combat Vehicle; ACV; Noise; Sound; Reduction; Heating, Ventilation and Cooling; HVAC; Climate; Maintainability

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