The present invention relates to a body thermal regulation system. The present invention also relates to a method for measuring heat fluxes in different parts of a body.
The rigors associated with diving are many. Surviving and capably functioning in cold or hot water temperatures are problems as old as diving itself. Water conducts heat away and toward the human body about 25 times faster than in air, and the heat capacity of water is greater than that of air by more than 3,500 times. The significant difference between rates of heat loss or gain at similar temperatures in air and when immersed in cold or hot water creates a distinct difference in the physiological effects associated with the two. Immersion in extreme cold or hot water environments can induce serious physiological effects that are potentially dangerous for a diver and since most diving is done in cold or hot water, adequate diver thermal protection is needed.
Currently, divers rely on insulated suits to keep them warm. Unfortunately, insulation is not sufficient for cold temperatures and generally not used in hot temperatures. The lack of adequate diver thermal protection in cold or hot water environments is currently mission limiting, although on-surface systems can provide marginally sufficient protection. These systems work via the use of a utility umbilical cord physically connecting the diver to a surface located support system which supplies the diver with heating or cooling fluid. However, because of the need for the utility umbilical cord, manueverability of the diver is severely limited, suggesting that there is a need for a flexible and portable thermal regulation system. Unfortunately, current portable systems are unsuitable for real world applications, being limited by power density requirements, complicated hardware, and insufficient real-time environmental and system controls.
In hot water environments, the problem of body thermal regulation is exacerbated because the diver cannot adequately rid his body of the inevitable heat produced by normal or accelerated metabolism. This is in contrast to cold water environments where metabolically-produced heat helps keep a diver warm. Furthermore, in hot water, there is additional heat gain from the hot surrounding ambient.
In addition, although measuring body core temperature and skin temperature is commonplace, the measurements of thermal balance in selected zones of the body has not been done. Moreover, efforts to integrate these measurements with a model to study internal heat storage and distribution have not been made.
The present invention is directed to overcoming these deficiencies in the art.
The present invention relates to a body thermal regulation system. The system includes a fluid-circulating garment having a plurality of fluid-impervious compartments where each compartment is in contact with a different part of a body. At least one heating/cooling unit is positioned to heat and/or cool fluid circulating to the fluid-impervious compartments in the garment. The system also includes a fluid circulation system positioned to circulate fluid between the heating/cooling unit and the plurality of fluid-impervious compartments in the garment.
Another aspect of the present invention relates to a method for measuring heat fluxes in different parts of a body. The method involves providing to a subject the body thermal regulation system according to the present invention described above. Then, the temperatures and flow rates of fluid entering and exiting each of the plurality of fluid-impervious compartments in the garment are measured. Finally, the heat fluxes in different parts of the body are determined.
The present invention discloses a total body thermal measurement system that also has the capability to alter and regulate the thermal status of a body. The body thermal regulation system of the present invention is capable of removing and delivering extra body heat independently from and to different zones of the body, respectively. This system has measurement and medical applications as well. Thus, the present invention also discloses a body thermal measurement system that is capable of determining the skin temperature and heat flux in different zones of a body, as well as the total body, allowing the estimation of deep body temperatures, distribution and storage of heat, convective heat transfer and core temperature using a thermal model to integrate the measured data.
The present invention relates to a body thermal regulation system. The system includes a fluid-circulating garment comprised of a plurality of fluid-impervious compartments which can be in contact with different parts of the body. At least one heating and/or cooling unit is positioned to heat and/or cool fluid circulating to the fluid-impervious compartments of the garment. The fluid circulation system is positioned to circulate fluid between the heating and/or cooling unit and the plurality of fluid-impervious compartments in the garment.
Body thermal regulation system 100 can further contain inlet manifolds 112A-B positioned to receive fluid from plurality of fluid-impervious compartments 103 in garment 102 and outlet manifolds 114A-B positioned to receive fluid from heating/cooling units 104A-E.
Body thermal regulation system 100 further contains controller 116, which is in electrical communication with heating/cooling units 104A-E and the fluid circulation system. The body thermal regulation system of the present system further contains at least one power source for providing power to the heating/cooling units and the fluid circulation system. The power source can be a fuel cell or a battery. Fuel cells which use hydrogen and oxygen to produce electricity, heat, and water can be used as the power source. In addition, fuel cells possessing high energy densities at low weights, such as portable underwater aluminum-oxygen fuel cells, can be used in conjunction with the body thermal regulation system of the present invention. When fuel cells are employed, the use of a waste heat recovery system (e.g., heat exchangers) that utilizes the unused heat from the fuel cell to heat the diver is particularly appropriate in cold water ambients. However, recent improvements, and projected future improvements, in battery technology allow the use of batteries having high power density and peak power as the power source for the body thermal regulation system of the present invention.
Body thermal regulation system 100 further contains housing 122 that encloses heating/cooling units 104A-E and pumps 106A-B, as well as other components of the system. In other embodiments, batteries 118A-B can be positioned within housing 122. Housing 122 can also form platform 124 for the external attachment of batteries 118A-B and air tank A. Housing 122 can be composed of thermal conducting materials. Further, certain parts of housing 122, such as the part forming platform 124, can be made of high thermal conducting material capable of collecting or dissipating excess heat 126. Examples of high thermal conducting material include, but are not limited to, copper, aluminum, and other metals and non-metals with high thermal conductivities. Gaskets 128A-B seal housing 122 from the external environment. In addition, body thermal regulation system 100 can further contain insulation layer 130 positioned outside of and adjacent to or as a part of fluid-circulating garment 102. Suitable insulations include insulation that can be used in conjunction with a fluid-circulating garment and can partially insulate the body from the environment, particularly in water, as the insulation described in U.S. patent application Ser. No. 10/645,726 to Mollendorf et al. The system of the present invention can also be used with currently available dry and wet suit designs, where fluid-circulating garment 102 would be positioned between the dry or wet suit and the diver's body. Body thermal regulation system 100 can also further contain harness straps 132 attached to housing 122 which allows the system of the present invention to be attached to a body.
The inside of housing 122 can be dry or, alternatively, housing 122 can be filled with a non-electrical conducting fluid, such as inert perfluorocarbons, E5 freon, fluorinated polyoxy propylene, and other non-electrically conducting fluids. Filling the housing with an incompressible fluid, or alternatively pressurized gas, can be advantageous in the case of high pressure underwater environments and for heat dissipation. If housing 122 is filled with fluid that is electrolytic, then each of the components within the housing must be individually sealed to make them impervious to the fluid.
The body thermal regulating system of the present invention may be portable or non-portable, i.e. stationary or fixed. In the case of a portable system used for heating or cooling a diver, the system would be attached to the back of the diver, allowing free movement of the diver in the water environment. In the case of a non-portable system used for heating or cooling a diver, the system would be based on shore, on a boat, or on any other platform suitable for diving applications, where the diver would be connected to the system via a utility umbilical cord that transports heated or cooled fluid and/or electrical power to the diver as necessary. If the system is used for heating or cooling an individual in non-water environments, the system can be stationed on any suitable platform depending on the mission or task to be completed with the system of the present invention.
In other embodiments, temperature sensors 508A-H are positioned throughout the system in order to regulate and measure the temperature of fluid within the system. Temperature sensors 508A-B are positioned to measure the temperature difference along power source 510. Temperature sensors 508B-C are positioned to measure the temperature along the “cold” side of heating/cooling unit 502, while temperature sensors 508C-D are positioned to measure the temperature difference along the “hot” side of heating/cooling unit 502. Temperature sensor 508E is positioned to measure the temperature of fluid in the system after the mixing of the “hot” and “cold” sides. In addition, heat exchanger 506C can be attached to power source 510, as a means of recycling waste heat from power source 510.
Flowmeters can also be positioned throughout the thermal regulation system of the present invention. Flowmeter 512A is positioned to measure the fluid flow rate in the “cold” side line of heating/cooling unit 502, while flowmeter 512B is positioned to measure the fluid flow rate in the “hot” side line of heating/cooling unit 502. In addition, flow regulators 514A-B can be positioned to regulate the flow in these lines of the system.
The system can also contain temperature sensor 508F positioned to measure the inlet temperature of garment 516. This temperature controls how much heat is transferred to or from phase change material 518, when phase change material is employed in the system of the present invention. In one embodiment, the phase change material can be designed to absorb or release heat at about 40° C., melting or solidifying based on the circumstances and transferring heat to the system through heat exchanger 506D.
If the pressure in the system becomes too high, pressure release valve 520 is positioned to shut off the flow of fluid into garment 516. Since the flow rate of fluid within garment 516 may be significantly less than the flow rate of fluid through power source 510, flowmeter 512C is positioned to measure the flow rate of fluid into garment 516, while flow regulators 514C-D are positioned to balance the flow rates. In addition, temperature sensors 508F-G are positioned to measure the temperature difference along garment 516.
Fluid entering garment 516 will perfuse through different zones at various temperatures, heating or cooling a body depending on the surrounding temperature. Backflow valve 522 prevents fluid from flowing back into garment 516 after it has already passed through garment 516. In addition, pressure instruments 524A-B are positioned to measure the pressure difference along garment 516, while temperature sensor 508H is positioned to measure the mixing temperature of fluid coming from garment 516 and an adjacent line.
The system of the present invention can also further contain filter 526 positioned to remove fibrous materials floating through the system. The suction pressure of pump 528 is measured by pressure instruments 524C-D, while temperature sensors 508H and 508C are positioned to measure the temperature difference along the pump. Bypass valve 530A relieves high pressure within pump 528, while bypass valves 530B-C are maintenance valves which can be opened when adjacent components are removed during specific functions. Shutoff valves 514E-F can be employed to force water to flow outside of filter 526, while shutoff valves 514G-H can be employed to force water to flow outside of pump 528. In addition, shutoff valves 5141-J can be employed to force water outside of phase change material 518 as needed.
In operation, the regulation of body temperature of an individual using a body thermal regulation system of the present invention, as shown in
Fluid from plurality of fluid-impervious compartments 103 of garment 102 exits through another set of fluid transporting tubes 108C-D and, via quick disconnects 110C-D, enters inlet manifolds 112A-B.
Temperature sensors such as the ones 222, 224, shown in
In one embodiment, the body thermal regulation system of the present invention can be set up so that the number of pumps, motors, inlet quick disconnects, and outlet quick disconnects employed directly coincides with the number of different compartments in the fluid-circulating garment, thereby individually regulating the temperature of different parts of the body. For example, the system can have multiple heating/cooling units and multiple pumps to individually heat or cool and pump fluid into different compartments in the fluid-circulating garment.
The present invention also relates to a method for measuring heat fluxes in different parts of a body. The method involves providing to a subject the body thermal regulation system of the present invention described above. Then, the temperatures and flow rates of fluid entering and exiting each of the plurality of fluid-impervious compartments in the garment are measured. Finally, the heat fluxes in different parts of the body are determined. The overall principle of this method is to utilize the above-described body thermal regulation system to measure heat fluxes in multiple body zones and, hence the total body. In one embodiment, each compartment of the fluid-circulating garment has fluid pumped through it (typically at a flow rate from about 0.3 l/min up to about 1.6 l/min) by a dedicated pump located inside a housing. By measuring the temperature at the inlet and outlet to and from the garment, as well as the water flow, the heat flux can be calculated for each of the different zones of the body. By design, the inlet to the fluid-circulating garment can exit the housing from a manifold, and the outlet from the garment can enter the housing from another manifold. By measuring the temperature differential between the two manifolds, the total body heat flux can be determined. Interfaced between the two manifolds are parallel arrangements of a plurality of heating/cooling units, controlled by an integrated controller that adjusts the duty cycle of the heating/cooling units and heats or cools the fluid circulating through them. The power requirement of the heating/cooling units needed to maintain the body's skin and deep core temperatures is an additional measure of total body heat balance. The system of the present invention can thus serve as a total body calorimeter.
In parallel with the system measurements of the present invention, temperature and heat flux measurements can also be made directly from the body without the need to measure the temperature and flow of fluid using the thermal measurement system of the present invention. Thus, thermocouples and heat flow disks can be attached to the different zones of the fluid-circulating garment both on the body and insulation sides of the garment. The elasticity of the fluid-circulating garment material can act to press the thermocouples and heat flow disks against the skin of an individual's body. In addition, an ingestible capsule can be swallowed by the subject which is used to measure the core temperature and the heart rate of the individual. Using these data, temperatures and heat fluxes for different zones of the body can be measured and then integrated to estimate a body's total thermal status.
The data from the system's and body's measurements can be recorded on computer via analog/digital converters and stored for subsequent analysis. A computer model, based on quantitative physiology measurements taken during thermal stress experiments, can then be used to calculate the thermal status of the different zones of a body as well as the total body. Thus, the combination of the computer model and the data from the system's and body's measurement can be used to calculate regional temperatures within each of the different zones of a body, as well as body core temperature.
There are no comparable systems, which are currently available that perform the tasks that the system of the present invention is capable of performing. It is a unique combination of thermal measures from the body and the mechanical system and, when combined with known physiological data, has the power to address various issues regarding thermal regulation and measurement of a body. The system of the present invention has capabilities beyond those currently available. For example, it will not only provide thermal protection, but will also do total body calorimetry of an individual performing many different dynamic activities. Another advantage is that the system has the potential to work in both air and water environments with a wide range of thermal parameters and at altitude and underwater depth. The system has the advantage of permitting measurements while the person is thermally comfortable in many environments. The use of the computer model noted above will not only allow estimates of deep temperatures, temperature distribution and physiological control, but also has the capability to predict the physiological response to environmental stress in unusual environments.
Furthermore, the present system also has novel occupational and environmental safety applications. Manufacturers, firefighters, and individuals working with hazardous materials can be exposed to elevated environmental temperatures. The system of the present invention can be used to quantitatively assess the thermal stresses experienced by these workers. This information can be used to develop mechanisms for protecting these individuals from thermal stresses when working in these environments. The thermal states of professional divers working on construction, rescue, or military operations can also be evaluated with this system and lead to more effective thermal regulation for these workers performing these operations. Indeed, the system of the present invention has great potential to aid in the development of increased safety standards for workers in many fields and can in fact actually protect workers from work-related environmental thermal stresses. The system has potential medical applications as well, since it can be used for the measurement of thermal stresses on a patient undergoing treatment and for protecting these patients from treatment and illness-related thermal stresses, including stresses experienced by multiple sclerosis patients and post-operation surgical patients. In addition, when the system of the present invention is used in its portable mode, it can provide cooling or heating to patients and medical personnel. In particular, patients with thermal sensitivities, such as patients with multiple sclerosis, could use this system allowing them the ability to perform their daily activities in a safe and comfortable manner.
The foregoing description of the specific embodiments will so fully reveal the general nature of the present invention that others skilled in the art can, by applying current knowledge, readily modify or adapt for various applications such specific embodiments without undue experimentation and without departing from the generic concept, and therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The means, materials, and steps for carrying out various disclosed functions may take a variety of forms without departing from the invention.
This application claims benefit of U.S. Provisional Patent Application Ser. No. 60/569,703, filed May 10, 2004, which is hereby incorporated by reference in its entirety.
The subject matter of this application was made with support from the Office of Naval Research (Grant No. N00014-02-10278). The U.S. Government may have certain rights in this invention.
Number | Date | Country | |
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60569703 | May 2004 | US |