FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
TITLE OF INVENTION
Improved cooling system for Superconducting transformer
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Kishor Uddhav Joshi, Sumedh Pundlik Pawar of Analytics Centre, CG Global R&D, Crompton Greaves Limited, Kanjur (E), Mumbai 400042, Maharashtra, India, both Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention


The invention relates to an improved cooling mechanism for superconducting transformer and any other device requiring to be maintained at cryogenic temperatures.
Superconducting transformers require cryogenic temperatures (77 K or below) to operate. This cooling is provided by a cryocoofer. It removes the heat from superconducting transformer and rejects it to a cooling medium like air, cooling water, chilled water etc. These media are available at temperatures typically around 280 to 330 K. The energy requirement of the cryocooler is strongly dependent on the temperature at which it rejects heat. Higher temperature of heat rejection increases energy consumption of the cryocooler. Also the cryocooler is less efficient compared to chillers if operated over the same temperature range. However, it is the only practical alternative available for maintaining liquid nitrogen temperature. Its energy requirement reduces and capacity increases as heat rejection temperature reduces. For this purpose, cooling water is preferred as a medium over air. But still, the heat rejection temperature does not get sufficiently low. This results in high energy requirement for the cryocooler and hence superconducting transformer. The high heat rejection temperature limits the capacity of the cryocooler and also the temperature at which superconductor can be maintained. This increases the quantity of superconducting material and hence the initial cost of superconducting transformer.
An object of the invention is to provide an improved cooling mechanism for superconducting transformer to remove heat from the superconducting transformers.
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Yet another object of the invention is to provide an improved cooling mechanism for superconducting transformer which reduce the heat rejection temperature of the cryocooler.
Another object of the invention is to provide an improved cooling mechanism for superconducting transformer with a cooling medium to the superconductor and thereby increasing the current carrying capacity.
An object of the invention is to provide an improved cooling mechanism for superconducting transformer, which can also save electricity at the time of cooling.
Another object of the invention is to provide an improved cooling mechanism for superconducting transformer which uses low grade heat resources like solar energy, waste heat, low pressure steam, hot water etc. as a source of heat.
According to the invention an improved cooling mechanism is provided for superconducting transformer which comprises a cryocooler and absorption chiller to remove heat from a superconducting transformer.
In accordance to the present invention, said cryocooler is Connected with superconducting transformer to circulate liquid nitrogen within the superconducting transformer to keep the superconductor cool.
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In accordance to the present invention, said absorption chiller is provided with cryocooler to absorb the heat from cryocooler by circulating refrigerants.
In accordance to the present invention, said absorption chiller cascading the cryocooler to reduce its electricity consumption
In accordance to the present invention,, said absorption chiller comprises evaporator, absorber, desorber, condenser and pump assembly.
In accordance to the present invention, said evaporator comprises inlet and outlet to ciozulstc rafrrgerartfs- ftWogrr the ccyvcavter.
In accordance to the present invention, said absorption chiller contains a refrigerants which absorb the heat of the cryocooler, it can be any refrigerants which absorb the heat for example ammonia.
In accordance to the present invention, a cryocooler is required to remove heat from a superconducting transformer. The cryocooler consumes much more electricity than the electrical losses of the superconducting transformer. Thi$ invention proposes to remove the heat in two stages viz. the heat from superconducting transformer is removed by a cryocooler which is cooled by an absorption chiller. This is done by operating a cryocooler which liquefies the nitrogen and circulates through the transformer. The evaporated nitrogen is taken back in cryocooler and liquefied again by compression and
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cooled with the help of a cooling medium. The heat from cryocooler is rejected to this cooling medium. The present invention uses liquid ammonia as a cooling medium. It gets evaporated by the heat from cryocooler. The cooling and liquefaction of ammonia vapor is done in an absorption chiller. The absorption chiller uses water as a absorption medium. The heat from the absorption chiller is rejected to the ambient by using air, cooling water etc. The absorption chiller use low grade heat like solar energy, waste heat from hot gases/hot water, low pressure steam etc. and thereby saves electricity.
This reduces the penalty factor of the superconducting transformer. This combination of cryocooler followed by absorption chiller results in reduced power consumption, operating cost, fixed cost and increased capacity of heat removal system. In the prior art, superconducting transformers cooling is provided by a cryocooler rejecting heat directly to fluids like air, cooling water etc. The energy requirement of the cryocooler is strongly dependent on the heat rejection temperature. It is reduced by using liquid ammonia. Ammonia boils around 240 K at atmospheric pressure. If evaporator is operated under vacuum, this temperature can be even lower. This reduces the energy consumption of the cryocooler and increases its capacity. Alternatively, the temperature of liquid nitrogen it supplies gets reduced.
Dated this 20th day of March 2009
(Ivan Bernard Fuller)
ofKhaitan&Co
Agent for the Applicants
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