THERMOELECTRIC DIRECT COOLING/HEATING HELMET
Field of the Invention
The present invention relates to a thermoelectric direct cooling/
heating helmet for industrial applications.
Background of the Invention
In hot ambient conditions, humans normally excel at maintaining
correct body temperature. Blood flow through the skin increases, and
perspiration provides evaporative cooling, until the radiative heat flux
received by the body surface, exceeds the possible cooling by
evaporation.
Further, when protective outer clothing must be worn, the
evaporation of perspiration is hindered, rendering the body's natural
cooling mechanisms ineffective consequently causing increase in body
temperature. This can lead to individuals suffering impaired
concentration, and loss of human efficiency, as well as fatigue.
When the body's natural cooling mechanisms become ineffective,
there is a need for artificial cooling. Such a system is sought to be created
in the helmet developed by the inventors of the present invention.
The solid state cooling microclimate-conditioning" unit developed by
the inventors of the present invention provides an optimal powerful
solution to the problems presented by demanding thermal conditions in a
steel plant.

Such a helmet while providing internal cooling, also serves to isolate
the internal micro-climate from the hot external environment to help
achieve optimal cooling.
US 2006/0101556 to Goldsborough titled "Crash Helmet with
Thermoelectric Cooling" describes a helmet provided with an air passage
through with air drawn and this air is then cooled by the cold side of a
thermoelectric module that cools the air passing over the cold surface.
The air is drawn.in by a fan. The resultant cold air conditions the head in
the helmet after being cooled by the thermoelectric element. This is
different from the MECON-ISA invention in which the thermoelectric
cooling system directly cools a helmet shaped inner thermally conductive
surface in order to cause cooling of the head surface located in contact
with or close to the inner side this helmet shaped surface. The present
invention works on the principle of cooling of the air layer between such
conductive surface and the head that is being cooled.
KR 10-2009-55025 to Jung Geum Ryang titled "Helmet For Cooling
And Heating In Which Cooling And Heating Function Is Added) describes a
thermoelectrically cooled helmet that provides for a thermoelectric
element cooler/that would cool a heat exchange fluid, which would, in
turn be in contact with the head to be cooled. The same arrangement
could be used for heating also. This cooling arrangement is fundamentally
different from the present invention and is not comparable.
US 2010/0005572 to Chaplin titled "Thermoelectric Crash Helmet
Cooling System With No Mechanically Moving Components or Fluids" is
described as one in which thermoelectric elements are placed in such a
way as to cool the user's head, while the hot side of the element is
provided with a serrated heat sink through which air is moved within an

enclosed passage to cool the hot side and then exit from the helmet. This
is quite different from the present invention, which provides for
individually cooled heat sinks for each thermoelectric element and for the
cooling side of the element to cool, instead a heat spreader, shaped like a
helmet itself and for this heat spreader to cool the head by cooling the air
gap between the spreader and the head. These two concepts are not
comparable.
US 5603728 to Freddy Pachys titled "Scalp Cooling / Heating
Apparatus" provides for thermoelectric cooling using thermoelectric
elements cooling an air space within a helmet, in direct communication
with an air space adjusted to the scalp of the weaver. Further, the
invention provides for a fluid path through the helmet in communication
with at least one thermoelectric module for moderation of temperature.
The invention further talks of sealing the air cavity between the scalp and
the helmet. The present invention, on the other hand, does not provide
for sealing of the air volume between the helmet and the scalp, nor does
it provide for a moderating fluid. This invention provides for a helmet
shaped thermal spreader to which all modules are thermally connected
from the cold side and for external heat sinks to extract the heat from the
hot side. The present invention provides for efficient external hot air
paths to extract maximum heat and to make sure of a high coefficient of
performance on the cold side to give efficient cooling to the head of the
user. The present invention is aimed at fulfilling the need for a low weight
long use helmet that could give an effective maximum cooling of about 20
deg.C between the external ambient and the internal space within the
helmet.
US 5193347 and US 036242 both to Yair J. Apisdorf titled "Helmet-
Mounted Air System for Personal Comfort" describes a design for an
external air stream to be directed at the face of the user. The system

provides for the production of a small air stream of 3 to 15 cfm at a small
temperature difference of upto 1 to 3 deg.C discharged over the face of
the user. The objectives of and embodiments in this patent are
substantially different from those of the present invention and there is no
similarity between the two.
JP 2011/000342 to Oki Takehiko titled "Head Cooling / Warming
Device" describes, briefly, a device in which a peltier device is used to
cool a helmet with the cold side pressing to a heat conductive sheet
consisting of a black lead sheet along with carbon fibre randomly
distributed.
None of the references mentioned above disclose a thermoelectric
direct cooling/heating helmet provided with a thermal distribution surface
internally which is separated from the shell surface by a layer of
insulation.
The purpose of the direct cooling helmet include:
• Helmet for use in hot environments.
• Designed to keep the head comfortable
• Aimed at the mobility of personnel that need to work in a hot
ambient.
• Powered by a battery pack.
• Enables mobility for 25 to 40 min.
Summary of the Invention
The present invention provides a thermoelectric direct cooling/
heating helmet provided with a heat distribution surface internally which
is separated from the shell surface by a layer of insulation. The shell is

made of fiberglass, the external and internal surfaces of the fiberglass
shell being insulated leaving openings for the extraction of heat from the
inner surface through the thermoelectric module units thermally bonded
to the inner conducting layer. The thermoelectric modules are thermally
connected with the inner heat distribution surface. Each thermoelectric
module is thermally connected to an external heat sink having an inbuilt
fan, thereby enabling the thermoelectric device to extract heat from the
inner heat distribution surface, when electrically powered. The external
heat sinks are oriented with respect to the helmet surface such that the
air-flows are independent and non-interfering. Electrical connections
within the helmet enable power supplies to be connected to the
thermolectric modules from within the helmet body, led from a power
supply connector at the back of the helmet. A harness on the inside of the
heat distribution surface separates the head surface from the surface of
the heat distributor by a small distance of typically 5 mm to 10 mm. The
helmet and a battery pack are separate sub-units which get connected to
each other in operation. The battery pack is worn at the waist using the
belt provided.
Brief Description of the Accompanying Drawings
Figure 1 demonstrates the Peltier effect;
Figure 2 shows a cross-section of a thermoelectrically cooled/heated
helmet according to the present invention, which shows the layers of
construction of the helmet;
Figure 3 shows a frontal view of the helmet according to the present
invention;
Figure 4 shows a top view of the helmet according to the present

invention;
Figure 5 shows a side view of the helmet according to the present
invention;
Figure 6 shows a front view of the helmet in test according to the
present invention;
Figure 7 shows a view of the overall look of the helmet according to
the present invention when in use (front);
Figure 8 shows the back view of the overall look of the helmet when
in use according to the present invention;
Figures 9 to 11 provide details of test results of trials carried out at
hot chamber at cooling mode; and
Figure 12 provides details of test results of trials of direct heating
helmet with heating yield.
Detailed Description of the Invention
Principle:
The above referred cooler is basically a cooling/heating system
based on the application of solid state thermoelectrics. Thermoelectric
cooling/heating is based on the Peltier effect, in which, when a current is
passed around a circuit of a. different materials, one junction gets heated
while the other junction is cooled, thus moving heat energy from one
surface to another, or from one object to another, the result being that of
cooling of one end and heating of the other.

By reversing the direction of current flow, the heating and cooling of
the two junctions are mutually interchanged.
The Heat Transfer Process:
Heat transfer is the transfer of heat from one place to another by
movement of fluids/air, When an object is at a different temperature from
its surroundings or another object. Heat exchange occurs in such a way
that the body and the surroundings reach thermal equilibrium; this means
that they are at the same temperature. Heat transfer always occurs from
a higher-temperature object to a cooler-temperature object. Where there
is a temperature difference between objects in proximity, heat transfer
will occur.
There are mainly three methods for the heat transfer.
* Conduction
* Convection
* Radiation
Conduction:
Conduction (thermal) is the process of heat transfer through a
medium or material without any movement of the medium or material.
Conduction is the transfer of heat by direct thermal contact of particles of
matter. The transfer of energy is primarily because of molecules in
vibration. Conduction occurs primarily in solids and also in liquids.
Steady-state conduction: Steady state conduction is the form of
conduction which happens when the temperature difference driving the
conduction is constant or has carried at a state of equilibrium, the spatial

distribution of temperatures (temperature field) in the conducting object
does not change any further. In steady state conduction, the amount of
heat entering a section is equal to amount of heat coming out. In steady
state conduction, all the laws of direct current electrical conduction can be
applied to "heat currents". In such cases, it is possible to take "thermal
resistances" as the analog to electrical resistances. Temperature plays the
role of voltage and heat transferred is the analog of electrical current.
Transient conduction: There also exists non-steady-state situations, in
which the temperature drop or increase occurs more drastically, such as
when a hot copper ball is dropped into oil at a low temperature. Here the .
temperature field within the object changes as a function of time, and the
interest lies in analyzing this spatial change of temperature within the
object over time. This mode of heat conduction can be referred to as
transient conduction. Analysis of these systems is more complex and
(except for simple shapes) calls for the application of approximation
theories, and/or numerical analysis by computer.
Convection:
Convection is the transfer of heat from one place to another by the
movement of fluids. The presence of bulk motion of the fluid enhances
the heat transfer between the solid surface and the fluid.
There are two types of convective heat transfer:
• Natural convection: When the fluid motion is caused by buoyancy forces
that result from the density variations due to variations of temperature in
the fluid. For example, in the absence of an external source, when the
mass of the fluid is in contact with a hot surface, the intra-molecular
distance increases, causing the mass of fluid to become less dense. When

this happens, the fluid is displaced because of the density difference, the
cooler fluid which is less dense sinks. Thus the hotter fluid transfers itself
towards a cooler volume of that fluid. Thus displacing the fluid and
indirectly transferring heat.
• Forced convection: when the fluid is forced to flow over the surface by
external source such as fans and pumps, creating an artificially induced
convection current.
Internal and external flow can also classify convection. Internal flow
occurs when the fluid is enclosed by a solid boundary such as a flow
through a pipe. An external flow occurs when the fluid extends indefinitely
without encountering a solid surface. Both of these convections, either
natural or forced, can be internal or external because they are
independent of each other.
Radiation:
Radiation is the transfer of heat energy through empty space. All
objects with a temperature above absolute zero radiate energy at a rate
equal to their emissivity multiplied by the rate at which energy would
radiate from them if they were a black body.
Thermoelectric Cooling:
Thermoelectric cooling uses the Peltier effect to create a heat flux
between the junctions of two different types of materials. A Peltier cooler,
heater, or thermoelectric heat pump is a solid-state active heat pump
which transfers heat from one side of the device to the other side against
the temperature gradient (from cold to hot), with consumption of
electrical energy. Such an instrument is also called a Peltier device, Peltier

heat pump, solid state refrigerator, or thermoelectric module.
Because heating can be achieved more easily and economically by
many other methods, Peltier devices are mostly used for cooling,
However, when a single device is to be used for both heating and cooling,
a Peltier device may be desirable. Simply connecting it to a DC voltage
will cause one side to cool, while the other side warms.
The effectiveness of the heat pump in moving the heat away from
the cold side is dependent upon the amount of current provided and how
well the transferred heat can be removed from the hot side.
By applying a low voltage DC power to a thermoelectric module,
heat will be moved through the module from one side to the other. One
module face, therefore, will be cooled while the opposite face is
simultaneously heated. It is important to note that this phenomenon may
be reversed whereby a change in the polarity (plus and minus) of the
applied DC voltage will cause heat to be moved in the opposite direction.
Consequently, a thermoelectric module may be used for both heating and
cooling, thereby making it highly suitable for precise temperature control
applications. A thermoelectric module can also be used for power
generation. In this mode, a temperature differential applied across the
module will generate a current.
A practical thermoelectric module generally consists of two or more
elements of n- and p-type doped semiconductor materials that are
connected electrically in series and thermally in parallel. These
thermoelectric elements and their electrical interconnects typically are
mounted between two ceramic substrates. The substrates hold the overall
structure together mechanically and electrically insulate the individual
elements from one another and from external mounting surfaces. Most

thermoelectric modules range in size from approximately 2.5-50 mm (0.1
to 2.0 inches) square and 2.5-5 mm (0.1 to 0.2 inches) in height. A
variety of different shapes, substrate materials, metallization patterns and
mounting options are possible in these devices.
Cooling capacity (heat actively pumped through the thermoelectric
module) is proportional to the magnitude of the applied DC electric
current and the thermal conditions on each side of the module. By
varying the input current from zero to maximum, it is possible to regulate
the heat flow and control the surface temperature.
Thermoelectric modules offer many advantages including:
• No moving parts
• Small and lightweight
• Maintenance-free
• Acoustically silent and electrically "quiet"
• Heating and cooling with the same module, (including
temperature cycling)
• Wide operating temperature range
• Highly precise temperature control (to within 0.1 deg C)
• Operation in any orientation, zero gravity and high G- levels
• Environmentally friendly
• Sub-ambient cooling
• Cooling to very low temperatures (-80 deg C) (depending on
the number of cascade
stages).
• Typically a surface of suitable shape or contour with
appropriately high.
DIRECT COOLING / HEATING HELMET:

Cooling is by conduction and the heat sink is convective type. The
helmet is fitted with thermoelectric module and heat sink. The cold side of
the module is in contact with the internally placed conducting thermal
distributor inside the helmet. The head cooling is by convection of the air
layer between the inner conduction surface and the surface of the head. A
rechargeable battery pack and electrical switch are fixed with the waist
belt.
The features of direct cooling helmet include:
• Operational temperature up to 55°C.
• Cools the internal space by 18°C to 20°C at max external
temperature.
• Helmet weighs 1.6 Kgs, while the battery pack weighs 0.9 Kg
to 1.5 Kg depending on the operational time, required.
• The helmet and battery pack are separate sub-units and get
connected to each other in operation.
• The battery pack is worn at the waist with the belt provided.
Principle of working:
• The unit works using the thermoelectric principle.
• Peltier devices are coupled with matched heat-sinks and fans,
to extract heat from the inner space and pump it to the external
ambient.

• Thus, as heat gets thrown into the helmet space from the
head surface, it is extracted by the thermoelectric cooling units into
the ambient.
• The external forced air movement that the fans generate is
largely from below the helmet towards the upwards direction, thus
conveying the air upwords.
• The heat distribution surface envelops the major part of the
surface of the head and effectively creates a common air volume
which enables the surface of the head to experience the same
environment as created by the operation of the thermoelectric
modules for the whole surface, uniformly.
• The heat distribution surface is cooled at multiple points, as
equidistant as possible, thus optimizing the temperature changes in
linear directions away from the cold spot.
instructional Aspects:
• The helmet is constructed based on a fiberglass shell,
provided with a heat distribution surface internally, which is
separated from the fiberglass shell surface by a layer of insulation.
• The external and internal surfaces of the fiberglass shell are
insulated leaving openings for the extraction of heat from the inner
surface through the thermoelectric module units thermally bonded
to the inner conducting layer.
• Thermoelectric modules are thermally connected with the
inner heat distribution surface.

• Each thermoelectric module is thermally connected to an
external heat sink and such heat sink has an inbuilt fan, thus
enabling the thermoelectric device to extract heat from the inner
heat distribution surface, when electrically powered.
• Thus the external heat sinks are oriented with respect to the
helmet surface such that the air-flows are independent and non-
interfering.
• Electrical connections within the helmet enable power supplies
to be connected to the thermolectric modules from within the
helmet body led from a power supply connector at the back of the
helmet.
• A harness on the inside of the heat distribution surface
separates the head surface from the surface of the heat distributor
by a small distance of typically 5 mm to 10 mm.
The sectional drawing of the helmet (Figure 2) shows the layers of
construction of the helmet.
Specifications:
* Weight of helmet : 1.6 Kg (approx)
* Weight of battery pack : 0.9 Kg to 1.5 Kg
* Battery capacity : 10 to 15Ah
* Operational Voltage : 12 VDC
* Maximum Temperature : 20°C
difference created
* Maximum Ambient : 55°C

* Materials of construction : Fiberglass, copper, aluminum,
insulation, epoxy, alumina.
Industrial Applicability:
This product can be used in the following environments:
* Steel Plants
* Power Plants
* Railways Maintenance workshops
* Nuclear plants
* Gasification areas
* Mine Shafts
* Chemical reactors

WE CLAIM :
1. A thermoelectric direct cooling/heating helmet provided with a heat
distribution surface internally which is separated from the shell surface by
a layer of insulation.
2. The helmet as claimed in claim 1, wherein the said shell is made of
fibreglass.
3. The helmet as claimed in claim 1 or 2, wherein Peltier devices are
coupled with matched heat-sinks and fans to extract heat from the inner
space and pump it to the external ambient.
4. The helmet as claimed in claims 1 to 3, wherein the external and
internal surfaces of the fiberglass shell are insulated leaving openings for
the extraction of heat from the inner surface through the thermoelectric
module units thermally bonded to the inner conducting layer.
5. The helmet as claimed in claims 1 to 4, wherein the said
thermoelectric modules are thermally connected with the inner heat
distribution surface.
6. The helmet as claimed in claims 1 to 5, wherein each thermoelectric
module is thermally connected to an external heat sink and such heat
sink has an inbuilt fan, thereby enabling the thermoelectric device to
extract heat from the inner heat distribution surface, when electrically
powered.
7. The helmet as claimed in claims 1 to 6, wherein the external heat
sinks are oriented with respect to the helmet surface such that the air-

flows are independent and non-interfering.
8. The helmet as claimed in claims 1 to 7, wherein electrical
connections within the helmet enable power supplies to be connected to
the thermolectric modules from within the helmet body led from a power
supply connector at the back of the helmet.
9. The helmet as claimed in claims 1 to 8, wherein a harness on the
inside of the heat distribution surface separates the head surface from the
surface of the heat distributor by a small distance of typically 5 mm to 10
mm.
10. The helmet as claimed in claims 1 to 9, wherein the helmet and a
battery pack are separate sub-units which get connected to each other in
operation.
11. The helmet as claimed in claims 1 to 10, wherein the battery pack is
worn at the waist with the belt provided.