Cooling of a Self-Contained Portable HSDAS Unit
- Created: Tuesday, 01 February 2011
John C. Stennis Space Center (SSC) provides rocket engine propulsion testing for NASA’s space programs. There are occasions when it would be useful to have a portable, mobile data acquisition system that could easily be set up as needed within our facilities’ hydrogen environment, and that could be employed quickly to economically support projects and anomaly investigations. Therefore, a project to develop a Self-Contained Portable High-Speed Data Acquisition System (HSDAS) Unit that will let NASA take advantage of recent advancements in computer technologies throughout ground propulsion test facilities without rebuilding existing systems is under consideration. This unit would be a practical, field-deployable tool that can be set up quickly, and it would be employed for acquiring data for addressing issues that suddenly arise.
The technology need is a method to maintain a temperature level in this portable unit during deployment in an in-situ, remote, outdoor environment. The portable, self-contained HSDAS would be housed in a Class II Division 1 Group B explosion-safe enclosure (to ensure safe operation in a hydrogen environment). The final HSDAS would be enclosed in a 1660 Pelican polymer case with a volume estimated to be about 9 cubic feet, with an operational weight of approximately 48 pounds.
The unit’s power system contains a dual 24V 100Ah lithium ion battery system, a battery management module capable of a 24V 40-Amp load, and a 24V 10A power regulation system. The power system is capable of temporarily supplying a 240W (24V @ 10A) load, but the normal power dissipation will be much less. The battery management module and regulation system may still dissipate additional power (possibly 2W). The sum of internal equipment power dissipation will be approximately 25W.
Due to heat generated by the electronic equipment and due to external heat (sun radiation and air temperature), an excessive amount of heat is accumulated near the electronics, compromising the safe and reliable operation of the unit. Therefore, it is necessary to find methods to remove heat from the unit. Since there are two sources of heat, it is necessary to devise two strategies for reducing the overall heat load:
- Preventing/reducing external heat (sun radiation and hot air) from heating the electronic components inside the HSDAS unit.
- Removing the heat that is generated by the HSDAS system, away from the unit.
When the unit is deployed in-situ, it will be outdoors in a hot (up to 100 °F) and humid (80% air-humidity) environment. This HSDAS unit must be able to operate in environments with radiant heating and ambient temperatures at >100 °F while keeping the electronics at <80 °F, within the portable HSDAS. The challenge is to develop a cooling system for the HSDAS unit that is capable of operating on the existing battery power for prolonged operating periods (over several days).
The challenge is a method to reduce the overall heat load on the electronic components generated by external heat sources (sun radiation, hot air) and by internal heat sources (electronic components). The proposed solutions must meet the following requirements:
- Keep the electronics at a temperature <80 °F.
- The cooling unit may not hinder the portability of the HSDAS unit (i.e., it may not be too heavy or too bulky).
- The cooling unit must be powered on the batteries of the HSDAS unit.
- The cooling unit may draw only a limited amount of power from the batteries in order to ensure the required prolonged operating periods (over several days).
- The unit must be appropriate to use in a Class II Division 1 Group B environment (areas made hazardous by the presence of combustible dust, e.g., finely pulverized material, in a hydrogen environment).
In submitting your solution, you may suggest alternative enclosures.