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, Pune411 019, Maharashtra, India
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.
1

FIELD OF INVENTION:
This invention relates to LiBr Vapor Absorption Heat Pumps (VAHPs).
In particular, this invention relates to LiBr Vapour Absorption Heat Pumps (VAHPs) with improved performance.
PRIOR ART:
It is already known in the prior art that LiBr Vapor Absorption Heat Pumps are used for producing cooling effect by utilizing heat as energy source. The performance of LiBr VAHP is dependent on number of factors such as heat- source temperature, design of absorption system, LiBr solution circulation rate and the like.
It is also known that by decreasing LiBr solution circulation rate, performance of the overall system can be substantially improved. For decreasing the solution circulation rate, one has to either operate at lower concentration level of LiBr in water in the absorber or at higher concentration level of LiBr in water in the generator.
Though technologies for operating at lower concentration levels by improving absorber heat transfer are well developed, there has been no major breakthrough in the technology for operating at higher concentration level of LiBr in solution.
DRAWBACKS
The main drawbacks of conventional LiBr Vapour absorption Heat Pump
are:

1. High concentration LiBr solution is susceptible to crystallization of LiBr salt at a temperature close to normal ambient temperature.
2. Operating at higher concentration level causes blockage of pipelines and heat transfer surfaces due to crystallization of LiBr when cooled to a temperature close to ambient temperature before entry to absorber.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a new method and apparatus by which the performance of the LiBr Vapour Absorption Heat Pump (VAHP) is improved.
Another object of this invention is to improve the performance of the LiBr Vapour Absorption Heat Pump (VAHP) without causing a blockage of pipelines / heat exchanger due to crystallization of LiBr at higher concentration levels.
Another object of this invention is to propose new system, which will reduce the size of the LiBr VAHP at the same performance level.
Another object of this invention is to propose an improved LiBr Vapour Absorption Heat Pump (VAHP) in which electrostatic treatment is utilized to improve its performance.
SUMMARY OF THE INVENTION:
It is envisaged in accordance with this present invention that the VAHP subjected to a electrostatic treatment of LiBr solution will be able to avoid a blockage of pipelines / heat exchanger due to crystallization of

LiBr at higher concentration levels than normally used in absorption cycles.
This invention also envisages a new system, which will improve the performance of LiBr absorption cycle.
In accordance of another aspect of this invention there is envisaged a method and apparatus for electrostatic treatment of LiBr solution whereby there is substantial decrease in the temperature at which LiBr salt in water begins to crystallize and form large size crystals.
The advantages of this invention are:
1. Substantial decrease in temperature at which crystallization of LiBr solutions takes place
2. Improvement in performance i.e. higher Coefficient of Performance (COP)
3. Improved recoverability
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 overall system incorporating electrostatic treatment
device or apparatus wherein reference numeral (1) indicates high
temperature generator, reference numeral (2) indicates high temperature
heat exchanger, and reference numeral (3) indicates a low temperature
heat exchanger, reference numeral (4) indicates a weak solution pump,

reference numeral (5) indicates evaporator, reference numeral (6) indicates an absorber, reference numeral (7) indicates a low temperature generator, reference numeral (8) indicates a condenser and reference numeral (9) indicates an electrostatic device.
Figure 2 illustrates the details of electrostatic device wherein reference numeral (10) indicates a high voltage DC generator, reference numeral (11) indicates an electrostatic probe and reference numeral (12) indicates a vessel filled with LiBr solution, which holds electrostatic probe. High voltage DC generator (10) and electrostatic probe (11) are operably connected by means of electric cables.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Each VAHP can be equipped with one set of electrostatic device, which is installed on the pipelines between low temperature generator (7) and low temperature heat exchanger (3).
The location of electrostatic device can be at other places also such as between (1) and (2) on (1), on (2), on (3), on (6), on (7), between (6) and (3) etc.
CYCLE DESCRIPTION
The operation of conventional LiBr VAHP is as follows:
In this system water is used as refrigerant and LiBr solution as absorbent. The refrigerant water is circulated and sprayed over the evaporator tubes in the evaporator (5) where it turns into water vapor. It absorbs heat

from the chilled water, which passes through the evaporator tubes and hence cools the same. Refrigerant water vapour enters absorber (6) and is absorbed by LiBr solution sprayed over the absorber tubes. The heat of absorption is taken away by cooling water flowing through the absorber tubes. The weak solution of LiBr formed thereby in the absorber is pumped to high temperature generator (1) by weak solution pump (4) through low temperature heat exchanger (3) and high temperature heat exchanger (2). In the high temperature generator LiBr solution is heated and gets concentrated. The refrigerant vapour thus formed is sent to tube side of low temperature generator where it condenses. The concentrated solution from high temperature generator is sent to the shell side of low temperature generator (7) where it is further concentrated to form strong solution. The water vapor generated is then condensed in condenser (8) by cooling water flowing through the condenser tubes. The refrigerant water condensed in the condenser and tube side of low temperature generator is throttled and returned to the evaporator. The strong solution generated in low temperature generator is cooled down in the low temperature heat exchanger and spread over the absorber tubes to complete the cycle.
In VAHP cycle, since the strong solution is cooled down to temperature which is fairly close to its crystallization temperature, there is always possibility of crystallization occurring in the low temperature heat exchanger or pipeline connecting low temperature heat exchanger to absorber where strong solution temperature is at it's lowest. Additionally, strong solution is sprayed on absorber tubes which are at temperatures very close to crystallization temperatures of strong solution.

In the proposed method, electrostatic charge is imparted in the strong
LiBr solution flowing from low temperature generator to low temperature heat exchanger with the help of high DC voltage and electrostatic probe. Due to similar electrostatic charge imparted on very small LiBr salt particles, there is a force of repulsion between these particles. This phenomenon prevents further crystallization or formation of large size crystals, which are responsible for blockage of pipeline or deposition of crystals on heat exchanger surface.
Apart from the device described above, such electrostatic charge can also be imparted by other devices such as magnetic apparatus, electromagnetic apparatus, etc. resulting in the improvement of performance of LiBr VAHP.
This invention envisages a method of improving LiBr VAHP performance by imparting electrostatic charge in the LiBr solution using different types of devices such as electrostatic probes, magnetic apparatus, electromagnetic apparatus, etc.
Particularly, the electrostatic charge is imparted in the LiBr solution with the help of high DC voltage.
This invention therefore envisages a system comprising a set of heat exchangers such as generators, absorber, condenser, evaporator, solution heat exchangers, pumps and electrostatic apparatus, suitably connected so as to improve performance of LiBr VAHP.
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 of April 2006

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