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Research Papers

Thermal Protection System for Underwater Use in Cold and Hot Water

[+] Author and Article Information
Joseph C. Mollendorf1

Center for Research and Education in Special Environments (CRESE), State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY 14214-3078molendrf@buffalo.edu

David R. Pendergast

Center for Research and Education in Special Environments (CRESE), State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY 14214-3078

1

Corresponding author.

J. Thermal Sci. Eng. Appl 2(1), 011003 (Jul 29, 2010) (12 pages) doi:10.1115/1.4001986 History: Received February 08, 2010; Revised June 07, 2010; Published July 29, 2010; Online July 29, 2010

Underwater workers, sport and military divers, are exposed to thermal stress since most of the waters of the world are below or above what is thermally neutral. Although divers wear insulation suits for passive thermal protection they are inadequate. Active heating is currently accomplished by resistive heating and open-flow tubes delivering hot water; however, these methods are problematic. The challenge of this project was to design, build and test an active diver thermal protection system (DTPS) to be used with wet suit insulation that is effective, user-friendly, reliable, and that could be used by a free-swimming diver. The DTPS has a minimum number of moving parts, is low maintenance, has no unsafe or toxic working fluid and uses no consumables except a safe, high density, modular electrical power source. A portable and swimmable, self-contained, electrically powered unit (DTPS) has been designed, built, and tested that produces and circulates thermally conditioned water in a closed-loop through a zoned tube suit worn by a diver under a wetsuit to maintain skin and body core temperatures within prescribed safe limits. The system has been validated by using physiological data taken on human subjects over a wide range of ambient water temperatures. Corresponding enthalpy and electrical power measurements were used as the basis of a thermodynamic analysis. The DTPS maintained skin and body core temperatures within safe and functional ranges by providing up to about 200 W of heating in cold water and up to about 330 W of cooling in hot water. The corresponding electrical power consumption was up to about 300 W in cold water and up to about 1500 W in hot water. The results of a complete audit of the power use and heat transfer are presented along with the efficiency of the thermoelectric heating/cooling modules and the duty cycle of the system for a range of water immersion temperatures from 10°C to 39°C. The DTPS proved to be an effective and reliable apparatus for diver thermal protection in water temperatures from 10°C to 39°C, which covers most of the range of the earth’s waters. The data presented here can be used to modify the design of the DTPS to meet specific needs of the diving community.

Copyright © 2010 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Schematic of tube suit layout showing body zone segments, parallel flow circuits and tube lengths. For a photograph of the suit see Ref. 14.

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Figure 2

The DTPS with its cover removed showing gear pumps (right inside), outlet and inlet manifolds (center inside), thermoelectric assembly (TECs) (left under plate), and control card inside the case. The pressure compensation system is also shown with its regulator (right of unit) and reserve tank (yellow). J.C. Mollendorf and D.R. Pendergast, “Body Thermal Regulation/Measurement System,” U.S. nonprovisional patent application serial No. 12/477,721 (filed June 3, 2009).

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Figure 3

Closed-loop water flow circuit schematic also showing power, flow work and heat transfer parameters

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Figure 4

Hydraulic schematic (a, upper) and pressure schematic (b, lower)

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Figure 5

Measured body core and skin temperatures shown are averages for eight human volunteer subjects at various ambient temperatures

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Figure 6

Thermodynamic schematic of DTPS, also showing TECs, LINES, and DIVER CVs within dashed lines

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Figure 7

Variation in TECs power with ambient temperature; data for each subject (filled circles) and interpolated average curve (line)

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Figure 8

Power variation with ambient temperature of TECs (bottom of bar graphs), pumps (second from bottom of bar graphs), FETS (third from bottom of bar graphs), and circuit (top of bar graphs)

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Figure 9

Variation in total electrical power in with ambient temperature; data for each subject (filled circles) and interpolated average curve (line)

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Figure 10

Variation in heating and cooling supplied to the diver with ambient temperature; data for each subject (filled circles) and interpolated average curve (line)

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Figure 11

Manifold temperature data; flow-weighted-average over all body zones for each subject (filled circles, upper plates) and interpolated average curves (lines). Upper left plate, supply manifold; upper right plate, return manifold; lower plate: solid line, supply manifold; dashed line, return manifold.

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Figure 12

Variation in FET power with ambient temperature; data for each subject (filled circles) and interpolated average curve (line)

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Figure 13

Variation in diver heat transfer to/from the ambient water with ambient temperature; data for each subject (filled circles) and interpolated average curve (line)

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Figure 14

Variation in COP of TECs with ambient temperature; data for each subject (filled circles) and interpolated average curve (line)

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Figure 15

Duty cycle data (filled circles) for each subject and interpolated average curves (lines) for heating in cold water (upper left plate), cooling in hot water (upper right plate), and combined (lower plate)

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