FIELD OF THE INVENTION
The present invention generally relates to a device and a method for full or
partial heating of solid or hollow, cylindrical or rectangular or square cross
sectioned object, which is uncooled or cooled by passing a fluid through hollow
space within the object, and in which cartridge type of electrical heaters are
embedded inside semi-circular or semi-rectangular solid blocks tightly held over
the outer periphery of the object. The device or method finds application in
manufacturing process to make an object flexible, for forming desired shaped
components or articles. The invention is further applicable for carrying out heat
transfer studies and also preheating / post heating during welding process. More
particularly, the present invention relates to a system for external, conductive,
partial or full heating of solid or hollow objects with cylindrical or rectangular or
square cross section up to high heat flux level.
BACKGROUND OF THE INVENTION
At present resistance heating method is used to heat a pipe cooled by fluid
passing through the hollow space within the pipe for carrying out
experimentation on fluid heat transfer. In this method, high DC current is
allowed to pass through the wall of the tube to be heated, which inter alia
requires that the tube to be heated is insulated from other structural and piping
components However this method cannot be used for partial heating
requirements. Also, the heat flux produced in this method is limited by the type
of material and dimensions of the object being heated.

Hence, there is a need to develop a new heating system which does not require
electrical isolation and enables partial heating of circumference to carry out
simulation studies to understand the heat transfer behavior of fluid passing
through a channel with cylindrical or square or rectangular cross section of an
object. The heating system for such application should be capable of providing
heat flux as high as 2000 kW/m2 or more simulating the hot spots of a process
for ensuring whether the given fluid flow rate is enough to maintain the metal
temperature within acceptable limit. These simulation studies are helpful in
developing equations for predicting metal temperature of the channels cooled by
fluid for the given operating conditions.
Also, there is a need to heat solid or hollow objects with cylindrical or rectangular
or square cross section in the manufacturing process to make them flexible to be
formed into desired shapes and manufacture components or articles for desired
utility. The heating system for such applications must be capable of uniformly
heating the object to the required temperature level at the desired heating rate.
In both applications, the heating system should have provisions to heat semi-
circumference or full circumference and should have a high turn down ratio of
maximum to minimum heat supply to meet the process / study requirement.
U S patent 3737627 for Electric test tube heater describes an electric test tube
heater having a self-supporting, free-standing electric resistance heating coil of
low mass attached to an electrically insulated from a support member adjustably
mounted for vertical movement on an upright stand. The coil is wound about a
vertical axis and has an internal diameter larger than the outside diameter of the
test tube to be heated.

A clamp is also fixed to the support member and is axially aligned with the coil
for holding the test tube so as to locate the lower portion thereof within the coil.
A channel-shaped reflective heat shield open at the top and bottom to allow
insertion of the test tube into the heater and having a vertical slot at the front to
permit visual inspection of the test tube during the heating process is fixed to the
support member and surrounds the coil. The support member is pivotally
attached to the stand whereby the heating coil, clamp, test tube being heated
and shield are all tiltable as a unit relative to the stand.
The heat transfer through this method is by radiation and is limited by the
temperature of the heating coil. If higher heat fluxes are to be obtained, this
method requires special heating coils with inert environment.
US 7,976,306 B2, Jul. 12, 2011,pertains to devices and methods for heating
pipes, tubing or similar equipment to melt-out blockages, such as for example,
bitumen blockages. This method of heating will not meet the requirement of
providing external heat of very high heat flux level.
Patent No. FR2985654B1 2014-04-25 for Radiator towel rail having at least one
bar towel holder a heat sink integrated in which is located an electric heating
cord. The invention relates to a towel-drying radiator comprising at least one
tubular towel-holding bar horizontally attached onto at least one vertical
member, an electrically-insulated electrical heating cable being arranged in said
bar, characterized in that: said cable is accommodated inside the body of a heat
sink, said body being made from a thermally conductive material, said body
being configured such that the entirety of the outer heating surface of said cable
is in contact with said body; and the heating assembly, consisting of said heat

sink and said cable, is inserted into said bar so as to ensure the continuous
surface contact between the inner wall of said bar and at least part of the outer
surface of the body of said heat sink over the entire length of the body.
In this method, the heat flow is from internal to external with limited heat flow in
a tubular section against the present requirement of heat flow from external to
internal in a solid or tubular section enabling very high heat flow.
Hence, the above inventions are not relevant to this present invention.
OBJECTS OF THE INVENTION
It is therefore an object of the inventipn is to propose to a system for external,
conductive, partial or full heating of solid or hollow objects with cylindrical or
rectangular or square cross section up to high heat flux level.
Another object of the invention is to propose to a system for external,
conductive, partial or full heating of solid or hollow objects with cylindrical or
rectangular or square cross section up to high heat flux level which is capable of
providing heat at the outer periphery of the object either for semi-circumference
or for full circumference.
A still another object of the invention is to propose a system for external,
conductive, partial or full heating of solid or hollow objects with cylindrical or
rectangular or square cross section up to high heat flux level which is applicable
for objects of any cross section.

A further object of the invention is to propose a system for external, conductive,
partial or full heating of solid or hollow objects with cylindrical or rectangular or
square cross section up to high heat flux level which is suitable for uncooled solid
or hollow and for cooled hollow objects.
A further object of the invention is to propose a system for external, conductive,
partial or full heating of solid or hollow objects with cylindrical or rectangular or
square cross section up to high heat flux level which can provide very high heat
flux up to 2000 kW/m2 with maximum to minimum power ratio up to 40.
Yet another object of the present invention is to propose a system for external,
conductive, partial or full heating of solid or hollow objects with cylindrical or
rectangular or square cross section up to high heat flux level maintain a constant
heat power or constant temperature of desired level through a control system.
A further object of the present invention is to propose a system for external,
conductive, partial or full heating of solid or hollow objects with cylindrical or
rectangular or square cross section up to high heat flux level which is easy to
mount and portable.
Yet another object of the present invention is to propose to a system for
external, conductive, partial or full heating of solid or hollow objects with
cylindrical or rectangular or square cross section up to high heat flux level which
includes a plurality of thermocouples for measuring the temperature of the
object being heated.

SUMMARY OF THE INVENTION
Accordingly, there is provided propose to a system for external, conductive,
partial or full heating of solid or hollow objects with cylindrical or rectangular or
square cross section up to high heat flux level.
The heating system consists of two semi cylindrical or semi rectangular solid
metal blocks having a plurality of longitudinal holes to house several cartridge
type of electrical heating elements; a plurality of multiple radial holes at locations
to allow fixing of corresponding number of thermocouples to measure the
temperature of the object to be heated; a multiple lug plates for assembling the
blocks over the object to be heated including assembling of the two half blocks
to cover full periphery of the object. The outer periphery of the metal blocks is
circular or rectangular as desired. This block is machined with an inner groove to
match the outer periphery of the object to be heated. The dimensions are
chosen such a way that when the blocks are assembled over the object, it
ensures a perfect contact over the full surface of the object to be heated. The
cartridge heaters are housed inside the said longitudinal holes in the metal
blocks. The dimensions of the holes and the cartridge heaters are selected such
a way that it ensures perfect contact over the full surface between metal blocks
and that of the cartridge heaters. The heating capacity and the number of
heaters could be selected as per the heat capacity requirement. Spring loaded
thermocouples passing through the radial holes in the metal block have perfect
contact with the object to be heated and indicate the temperature of the object
to be heated at the desired locations. The bolted connections enable easy
assembling and dismantling of the blocks. The length / height of the block is
chosen such a way it is portable.

Thermal insulation of adequate thickness is used between semi heater blocks
and externally all around the heater block assembly to reduce heat conduction
and loss during the use of the heating system for the desired application.
Each heater block is provided with 415 V electric power supply through a
thyrister based power control panel enabling maintenance of steady state of
power or temperature at any desired level. Operation of the power supply to one
block meets the heating requirement of one semi periphery of the object. When
both the blocks are given with power supply, the object gets heated up for the
full periphery.
Thereby the drawbacks mentioned in the background is overcome by the present
invention.
pPTFF nFCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 shows the proposed arrangement with semicircular heating blocks and
hollow circular object.
Fig. 2 shows the proposed arrangement with semicircular heating bocks and solid
circular object.
Fig. 3 shows the proposed arrangement with semicircular heating bocks and
hollow rectangular object.
Fig. 4 shows the proposed arrangement with semicircular heating bocks and solid
rectangular object.

Fig. 5 shows the proposed arrangement with semicircular heating bocks and
hollow square object.
Fig. 6 shows the proposed arrangement with semicircular heating bocks and solid
square object.
Fig. 7 shows the proposed arrangement with semi rectangular heating blocks
and hollow circular object.
Fig. 8 shows the proposed arrangement with semi rectangular heating bocks and
solid circular object.
Fig. 9 shows the proposed arrangement with semi rectangular heating bocks and
hollow rectangular object.
Fig. 10 shows the proposed arrangement with semi rectangular heating bocks
and solid rectangular object.
Fig. 11 shows the proposed arrangement with semi rectangular heating bocks
and hollow square object.
Fig. 12 shows the proposed arrangement with semi rectangular heating bocks
and solid square object.
Fig. 13 shows the circuit diagram of the power supply for the proposed heating
arrangement.

The present invention relates to a device or a method for full or partial heating of
solid or hollow, cylindrical or rectangular or square cross sectioned object,
uncooled or cooled by fluid passing through hollow space within the object, using
cartridge type of electrical heaters embedded inside semi-circular or semi-
rectangular solid blocks tightly held over the outer periphery of the solid or
hollow, cylindrical or rectangular or square object.
nFTATLED DECRIPTION OF THE ACCOMPANYING DRAWING
The heating system consists of two semi cylindrical (2) or semi rectangular (14)
solid metal blocks having plurality of longitudinal holes to house cartridge type of
electrical heating elements (7), radial holes at appropriate locations to allow
fixing of thermocouples (8) to measure the temperature of the object to be
heated and lug plates (3) for assembling the blocks over the object to be heated
to cover full periphery of the object using bolts, nuts an
d washers (4, 5, 6). The outer periphery of the metal blocks shall be circular (2)
or rectangular (14) as desired. This block is machined with an inner groove to
suit the outer periphery of the object (1, 9, 10, 11, 12, 13) to be heated. The
dimensions are chosen such a way that when the blocks (2 or 14) are assembled
over the object (1, 9, 10, 11, 12, 13), it ensures perfect contact over the full
surface of the object to be heated. The cartridge heaters (7) are housed inside
the longitudinal holes in the metal blocks (2 or 14). The dimensions of the holes
and the cartridge heaters (7) are selected such a way that it ensures perfect
contact over the full surface between metal block (2) and of the cartridge heater
(7).

The heating capacity and the number of cartridge heaters (7) could be selected
as per the total heating capacity requirement. Spring loaded thermocouples (8)
passing through the radial holes in the metal blocks (2 or 14) have perfect
contact with the object (1, 9, 10, 11, 12, 13) to be heated and indicate the
temperature of the object to be heated at the desired locations. The bolted
connections (4, 5, 6) enable easy assembling and dismantling of the blocks (2 or
14). The length / height of the blocks (2, 14) is chosen such a way it is portable.
Each heater block is provided with 415 V electric power supply (15) through
thyristor based power control panel (16) connected by power cables (17)
enabling maintenance of steady state power or temperature at any desired level.
Operation of power supply to one block meets the heating requirement of one
semi periphery of the object. When both the blocks are given with power supply,
the object gets heated up for the full periphery.
Thermal insulation of adequate thickness is used between semi heater blocks
and externally all around the heater block assembly to reduce heat conduction
and loss during the use of the heating system for the desired application.

WE CLAIM :
1. A system for external, conductive, partial or full heating of solid or hollow
objects with cylindrical or rectangular or square cross section up to high heat
flux level comprising:
- at least two metal blocks having curved (2 or 14) outer periphery and with
inner groove to match the outer periphery of the object (1) to be heated,
a plurality of longitudinally formed holes on the metal blocks housing
plurality of cartridge type of electrical heaters (7), a plurality of
thermocouples (8) passing radially through the metal blocks (2 or 14)
disposed in contact with the object (1) to be heated, which are assembled
over the object to be heated (1 or 9 or 10 or 11 or 12 or 13) using a
plurality of lug plates (3) and fasteners (4, 5 ,6);
- wherein the set of cartridge heaters (7) in each block are separately
connected to 415 V AC power supply (15) through a thyristor control
panel (16) and power cables (17) for supplying and controlling 230 V
power to individual heaters enabling uniform heat supply including desired
turn down ratio in the heating power supply; the power supply (15) being
capable of providing high heat flux up to 2000 kW/m2 with maximum to
minimum power ratio up to 40, and

- wherein the thyristor control panel (16) is capable of maintaining
constant temperature of the object to be heated or maintaining
constant heating power.
2. The heating system as claimed in 1, wherein the system is designed
to adapt semi rectangular (14) heating blocks.
3. The heating system as claimed in 1 and 2, wherein heat objects of any
shape such as a solid circular section (9), hollow rectangular section
(10), solid rectangular section (11), hollow square section (12) and solid
square section (13) with inner groove in the metal blocks (2 or 14)
matching with the outer periphery of the object (9, 10, 11, 12, 13) can
be heated.
4. The heating system as claimed in any one of claims 1 to 3, wherein the
object can be cooled or uncooled solid or hollow object.

5. The heating system as claimed in any of claims 1 to 4, wherein the
system is extendable to any length to cover desired length of the
object to be heated.