FORM – 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL
Specification
(See section 10 and rule 13)
LiBr VAPOUR ABSORPTION HEAT PUMP THERMAX LIMITED
an Indian Company
Chinchwad, Pune 411 019, Maharashtra, India
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.
1

FIELD OF INVENTION:
This invention relates to a LiBr Vapor Absorption Heat Pump (VAHP).
PRIOR ART:
It is already known in the prior art that conventional configuration of
HTG in a Direct fired LiBr Vapor Absorption Heat Pumps is of two
types.
Majority of the HTG designs are of Shell and tube type of configuration where LiBr bromide solution is on the shell side i.e. outside the furnace where fuel is fired and outside the tubes through which flue gas flow takes place.
There are few HTG designs where fuel is fired in furnace surrounded by LiBr solution and a plate heat exchanger to transfer heat between flue gases and LiBr solution.
DRAWBACKS
The main drawbacks of the conventional shell and tube type HTG of LiBr Vapor Absorption Heat Pump are:
1) The quantity of LiBr solution required is very high and contributes substantially to the overall cost of the machine.
2) In direct fired units with heavy oil as fuel, the tube diameters required are generally larger to avoid frequent fouling of surfaces due to soot and this further increases the size of HTG and the LiBr content in HTG.

3) PHE type of HTG designs have substantially lower LiBr content as compared to conventional shell and tube type. But their application is limited to gas fired units as the passage of flue gas flow is very small and tends to choke due to soot even with firing of light oil.
SUMMARY OF INVENTION:
In particular this invention relates to the development of a new configuration of HTG for Direct fired LiBr VAHP, which is of water tube type construction.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a new configuration of HTG in LiBr Vapor Absorption Heat Pump, which is of water tube type of construction i.e., LiBr solution within HTG is completely inside the tube and the flue gases flow over the tubes.
Another object of this invention is to substantially reduce LiBr solution content of the HTG in LiBr VAHP.
Another object of this invention is to propose a new configuration of HTG which is suitable for direct firing of gas / light oil and even heavy
oil.
Another object of this invention is to propose new design of HTG, which has Air Preheater integral to the HTG.
Another object of this invention is to propose a new design of HTG, which has LiBr solution inside the tubes and the circulation of LiBr solution may be natural or forced circulation.

ADVANTAGES
The advantages of the invention are: Substantial reduction in LiBr solution content Reduction in overall cost
BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will be described in detail with reference to a preferred
embodiment. Reference to this embodiment does not limit the scope of
the invention.
In the accompanying drawings:
Figure 1 illustrates the overall scheme of new HTG connected to rest of
the components of VAHP.
Figure 2 illustrates new HTG details where (1) is the Furnace or combustion chamber along the axis of which from one end fuel is fired by any known means and the air is supplied either by blower/blowers (forced / balance draft). The furnace design can either be of straight flue or reverse flue type. In the straight flue type the products of combustion exits from the rear end of the furnace. In reverse flue design the products of combustion exits from the front end of the furnace as shown in figure 2.
The Furnace or combustion chamber is made of tubes, helically wound forming a coil (2). The coil can be a closed coil. It can also be a helically wound tubes with flats welded in between forming a membrane wall type of construction as shown in figure 2. Each turn of the helical coil is then drilled at top & at the bottom. Bottom header (3) and top header (4) are formed over the coil itself as shown in the figure 2 and then connected to separator (6) by means of riser (5). The coil can also be connected to the

bottom header (3) and top header (4) by means of stub (8) and then to separator (6) by means of riser (5) as shown in figure 3.
The LiBr solution and vapor formed in the coil (2) is taken to top header and through riser to separator (6) where refrigerant vapor is separated from LiBr solution. Part of LiBr solution is circulated back to bottom header (3) by means of down comer (7) and forms natural circulation loop. The remaining LiBr solution and water vapor is taken away from the separator to further components in the VAHP cycle.
The configuration described above is of natural circulation type where any pump does not force flow of LiBr through HTG. With the above knowledge, the configuration of HTG with forced circulation type can also be easily made where LiBr solution is forced through HTG tubes with the help of a pump.
The products of combustion, exit the furnace and enter the annular space between the helical coil and a jacket made of steel, which forms the convection bank. In the convection bank the products of combustion exchanges heat with the LiBr solution in the coil. In some cases where inner jacket air cooling is provided the products of combustion exchanges heat with both the LiBr solution in the coil and with the cooling air flowing through the annular between the inner jacket and a second outer jacket. The heated air in such cases is used as combustion air.
While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the

invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly
understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
Dated this 7th day of April 2006

Mohan Dewan
of R. K. Dewan & Co
Applicant's Patent Attorney