FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
An improved heating element
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S)
D'Melo Dawid and Singal Vivek of Crompton Greaves Ltd., Advanced Materials & Process Technology Centre (AMPTC) R&D, Bldg. No. 2, CG Global R&D Centre, Kanjurmarg (East), Mumbai - 400042, Maharashtra, India and Sarma Budhavarapu Pavan Srinivas and Garg Damodar of Crompton Greaves Ltd., Reliability Centre R&D, Bldg. No. 2, CG Global R&D Centre, Kanjurmarg (East), Mumbai - 400042, Maharashtra, India; all Indian Nationals.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION:
This invention relates to the water heater.
Particularly, this invention relates to improved heating element of the water heater.
BACKGROUND OF THE INVENTION:
A heating element converts electricity into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element.
Appliances for providing a more-or-less constant supply of hot water are variously known as water heaters, hot water heaters, hot water tanks, boilers, heat exchangers, calorifiers, or geysers depending on whether they are heating potable or non-potable water, in domestic or industrial use and their energy source.
Electric water heaters have heating elements inside the tank to heat the water. The heating element is one of the most important features in electrical heaters. These heating elements are generally made of metal and get hot from electrical resistance. These heating elements range in power consumption from 2kW to 4kW in domestic units, and up to 72kW for industrial units.
Electrical heaters for liquids have been around for a long time. In the known art, the heating element is usually made up of metal. However, salt and other impurities present in the water, come in contact with the heating element, resulting in scale

formation.
Water heaters are meant to act on water of varying hardness. Hardness in water is quantified by the amount of calcium and magnesium ions present in it. Most of these salts show decreasing solubility with an increase in the solution temperature, leading to their precipitation in the form of the crystals which is known as scaling. Scaling on the heating element of the water heater occurs due to the deposition of insoluble calcium and magnesium carbonates, silicates and other insoluble salts on the heating element of the water heater.
Manufacturers of elements consider a nominal thickness of scale greater than 1/16 inch as excessive. Excessive scale build-up reduces the efficiency of the geyser since the scale has a lower thermal conductivity. This results in the water taking a longer time to heat as the scaling increases. Although normally found in hard water areas, softened water can also cause scaling. The scale tends to act as an insulator around the element. Heat is no longer being transferred to water at the proper rate. A build-up of heat in the element occurs, exceeding the operating temperatures of the element, resulting in element failure.
Various solutions have been proposed to prevent or inhibit the deposition of scales on heating element of the water heaters.
The Chinese Patent CN2712034 discloses the use of a Teflon coating on a metal substrate for the purpose of providing an anti-corrosive coating as well as a coating which will prevent the formation of scale. However, the disadvantage of a pure Teflon coating on the heating element is that it is a bad conductor of heat. This

would lower the efficiency of the heating element.
Thus, a need remains to provide a coating to prevent scaling on the heating element without affecting the heating efficiency of the heating element.
OBJECTS OF THE INVENTION:
An object of the invention is to provide an improved heating element of water heater wherein the said element is coated with the composition comprising teflon and nano-particles.
Another object of the invention is to provide an improved heating element of water heater wherein the said element is coated with the composition comprising Teflon and nano-particles, thereby preventing the scale deposition and scale build-up on the heating element of a water heater.
Yet another object of the invention is to provide an improved heating element of water heater wherein said element is coated with the composition comprising Teflon and nano-particles, thereby improving the heating efficiency of the heating element.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates the graphical representation of the variation in heating efficiency of heating element with or without various types of coating.

Figure 2 illustrates the graphical representation of the variation of scale deposition on the heating element with various coatings.
DETAILED DESCRIPTION OF THE INVENTION:
According to the invention, there is provided an improved heating element wherein an external surface of the said heating element is coated with the composition comprising teflon and nano-particles, said coating preventing the scale deposition and scale build-up on the heating element and improving the heating efficiency of the heating element.
According to a preferred embodiment of the invention, the nano-particles used in the said coating are selected from a group comprising elements with a high thermal conductivity.
Particularly, the nano-particles in the said coating composition are selected from but not limited to alumina, silica, aluminium nitride, boron nitride, silicon carbide and the like.
More particularly, the nano-particles in the said coating are of alumina.
More particularly, the nano-particles used in the said coating are in the range of 0.01 to 10.0%.
The coating on the surface of the heating element is done using conventional methods such as dipping, spraying, plasma vapor deposition, preceded by

conventional surface preparation techniques such as grease removal, sandblasting and the like.
The addition of nano-particles in Teflon is done by dispersing the powders in the Teflon formulation under a combination or stand alone method of ultrasonication and high speed dispersion. Other conventional methods can be used to disperse the nano-particles in the Teflon formulation by those knowledgeable in the art.
The improved heating element used is any heating device like a copper or stainless steel 2kW heating element.
The addition of the nano-particles in the Teflon coating helps in the inhibition of scale deposition and scale build-up on the heating element and also leads to improvement in the heating efficiency of the heating element.
The following experimental examples are illustrative of the invention but not limitative of the scope thereof:
EXAMPLE
The external surface of heating element (A) is coated with composition comprising only Teflon. The external surface of heating element (B) is coated with composition comprising Teflon and nano particles. The heating element (C) is uncoated. All the three elements are used in separate geysers and compared for the scale deposition and heating efficiency.

Figure 1 illustrates the graphical representation of the variation in heating efficiency of heating element with or without various types of coating. As illustrated in Figure 1, the heating efficiency of the heating element coated with Teflon containing nano-alumina is more as compared to that of heating element coated with only Teflon.
Figure 2 illustrates the graphical representation of the variation of scale deposition on the heating element with various coatings. As illustrated in Figure 2, the scale deposition is the highest in case of uncoated heating element. It is considerably less for heating element coated with only Teflon. Heating element coated with Teflon containing nano-alumina shows the least amount of scale deposition.
Table 1 illustrates the comparison of results with respect to the heating efficiency and scale deposition between the conventional uncoated heating element, heating element with Teflon coating and scale-inhibiting heating element of the invention

Sr no Heating element type Scale deposition time (hrs) (g) in Temperature attained (°C) in time (mins)

5 hrs 11
hrs 22 hrs 29
hrs 15
mins 25 mins 30 mins 40 mins 50 mins
1 Uncoated heating element 3.16 8.9 20.3 27.42 70 83 89 94 96
2 Heating element coated with pure Teflon coating 1.92 6.65 14.7 20.27 66 80 87 92 95
3 Heating element coated with Teflon containing 0.5% alumina 1.9 6.61 15.26 20.15 68 82 88 93 96

We claim,
1. An improved heating element wherein an external surface of the said heating element is coated with the composition comprising teflon and nano-particles, said coating preventing the scale deposition and scale build-up on the heating element and improving the heating efficiency of the heating element.
2. The improved heating element wherein the nano-particles used in the said coating are selected from but not limited to alumina, boron nitride, silicon carbide and the like.
3. The improved heating element wherein the nano-particles used in the said coating are of alumina.
4. The improved heating element wherein the nano-particles used in the said coating are in the range of 0.01 to 5.0%.