FIELD OF INVENTION
This invention relates to an improved solar flat plate collector.
BACKGROUND OF THE INVENTION
Solar flat plate collector is as such known in the art which uses a blackened metal sheet so as to absorb solar radiation in which a set of parallel metal tubes in meandering or parallel are welded to the metal plate on its upper surface. This provides a parallel or meandering path for the thermic fluid (usually water), which gets heated up. Further, the back side of the metal sheet is insulated and the whole set up is installed on steel angle frame. The insulation and the minimum thickness of the metal sheet is such that it can withstand the welding, which adds to the cost.
In another embodiment, the welding of the metal tubes is carried out by cladding two metal sheets, which are indented so as to form narrow channels through which thermic fluid such as water flows. However, thermal insulation on the under side is still required. This flat panel is provided with a glass plate on the front side which is separated from the metal plate by a few centimeters and the air in between is trapped by a suitable thermally insulated frame. This causes 'green house' effect which leads to rise in the temperature of the panel.

Another collector known in the art is evacuated tube collector wherein a blackened tube is enclosed in an outer glass tube casing and the space in between the two is evacuated and sealed.
The solar radiation incident on the tube is absorbed by the blackened tube inside and the glass envelope provides the green house effect with the vacuum in between preventing the heat loss by conduction and convection.
In the aforesaid embodiments, the tubes in the heat collector are connected to an overhead insulated tank and the heat inside the blackened tubes is transferred into the tank through natural convection of the thermic fluid (water) or by forced convection, in which case the tank need not be an over head one.
However, the drawback associated with the known arts is that, they are considerably expensive and require highly energy intensive materials.
OBJECTS OF THE INVENTION
The primary object of the present invention is to propose an improved solar flat plate collector using bamboo slats which is also very cost effective unlike known art.

Another object of the present invention is to propose an improved solar flat plate collector which is simple and efficient using the natural bamboo splits/slats.
STATEMENT OF INVENTION
According to this invention, there is provided an improved solar flat plate collector comprising of a plurality of bamboo splits/slats connected to each other in parallel such that their concave surfaces face one side and are provided with a water (thermic fluid) proof layer.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 shows: bamboo splits/slats connected to each other. Fig. 2 shows: present invention.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS;
Reference may be made to the accompanying drawings disclosing an improved solar flat plate collector comprising of a plurality of bamboo

splits/slats connected to each other in parallel such that their concave surfaces face one side and are provided with a water (thermic fluid) proof layer. The latter layer follows the contour of the concave surfaces of the bamboo slats. The concave surface side is covered with a flat metal sheet (a galvanized iron as an example) so that between the metal sheet and the bamboo splits/slats, multiple channels, nearly parallel are formed through which the thermic fluid can flow. The top surface of the metal sheet is blackened to absorb solar radiation.
Further, as a variant, proper connections at the alternate ends of the successive parallel channels may be provided so as to form a meandering channel for transferring solar thermal energy to the thermic fluid(water as an example) flowing inside the channels.
Alternately, the parallel channels may be connected through one cross channel at each end wherein the thermic fluid enters from one end and the hotter fluid exits from the other end. In a natural convective circulation, the cooler fluid enters at the bottom, gets heated and rises to the top.
As usual, a glass cover plate is provided away from the metal sheet so as to provide the necessary green house effect.
The metal sheet is provided with a hole each at top and bottom portions so that water enters into the channels through bottom hole and exits

through the top hole and the heat of the thermic fluid is transferred to the overhead insulated tank in the natural convection.
The inner soft part of bamboo which is in close contact with the overlay carrying hot water has the best thermal insulation for a given bamboo and the resin/glue or epoxy that fixes the bamboo inner surface to the over lay may be filled with fiber pulp for further enhancing the insulation.
The bamboo slat provides considerable thermal insulation and most of the mechanical support. The gradual variation of bamboo from its soft interior to the tough exterior is recognized to be a desirable functionally graded behaviour for the mechanical strength. It is recognized in the invention that this functional gradation (i.e. a gradual decrease in thermal insulation from soft interior to the hard exterior) is also beneficial from thermal insulation view in the bamboo based solar flat plate collector described in this invention.
Variants:
a) A thin metal sheet may hug the concave surfaces of the
split/ slats of the bamboo panel to provide water proofing.
b) The space between the bamboo slat and the thin metal sheet
that hugs the concave surface of the bamboo slat may be filled
with a suitable foam that acts as a bond between them.

c) The thermic fluid could be even air or any other suitable one
with an appropriate fluid proof covers on the concave face of the
bamboo panel.
d) Phase change materials may be provided in the parallel
channels as a filler and appropriate tubes could be laid in these
in which thermic fluid circulates.
e) The back of the bamboo panels could be insulated with rice
husk or suitable foams. These foams may be reinforced with
rice husk or dry stems of grass or coir etc., which double as
filler.
f) The parallel channels instead of being separated individually by
the over lay sheet, could be divided into three or four groups by
suitable rubber spacer gaskets between the ridges of the
selected parallel troughs and the underside of the metal sheet.
g) The holes for the entry and exit of the thermic fluid can be from
the bamboo panel side.
h) As is known in art, the single glass cover may be replaced by a double glass cover for achieving higher temperatures for the thermic fluid.
i) The insulated water tank and/or the pipes connecting the tank to the flat plate collector can be made out of the bamboo slats with proper inner fluid proof layer and an outer additional insulation. The bamboo slats properly held in place by suitable straps (of for example metal, plastic or bamboo slivers) which would provide most of the mechanical strength and part of the thermal insulation needed.

This would offer cost effective isolation of the fluid currents with out lateral flow.
The low cost of bamboo in providing the partially insulated ducting for the thermic fluid and the possibility of using substantially thin metal sheets together result in substantial cost reduction so that these could be integrated with the roof or wall of a building leading to the realization of building integrated solar thermal collectors.
The above provision would reduce the heat gain of the building that in turn results in substantial reduction in air conditioning costs.
Thus, the present invention has got wider industrial application in solar thermal energy, housing and other sectors.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM;
1. An improved solar flat plate collector comprising of a plurality of
bamboo splits/slats connected to each other in parallel such
that their concave surfaces face one side and are provided with
a water (thermic fluid) proof layer.
2. An improved solar flat plate collector as claimed in claim 1
wherein the concave surface side is covered with a flat metal
sheet.
3. An improved solar flat plate collector as claimed in claim 2
wherein a plurality of channels are provided between the metal
sheet and bamboo splits/slats through which the thermic fluid
can flow in which top surface of said metal sheet is blackened.
4. An improved solar flat plate collector as claimed in any of the
preceding claims wherein alternate ends of the successive
parallel channels may be connected so as to form a meandering
channel for transferring solar thermal energy to the thermic
fluid.
5. An improved solar flat plate collector as claimed in any of the
preceding claims wherein the parallel channels may be
connected through one cross channel at each end wherein the
thermic fluid enters from one end and the hotter fluid exits from
the other end.

6. An improved solar flat plate collector as claimed in any of the
preceding claims wherein a glass cover plate is provided away
from the metal sheet so as to provide the necessary green house
effect.
7. An improved solar flat plate collector as claimed in any of the
preceding claims wherein the metal sheet is provided with a
hole each at top and bottom portions so that water enters into
the channels through bottom hole and exits through the top
hole and the heat of the thermic fluid is transferred to the
overhead insulated tank.
8. An improved solar flat plate collector as claimed in any of the
preceding claims wherein inner soft part of bamboo is in close
contact with the overlay and resin/glue or epoxy fixes the
bamboo inner surface to the overlay may be filled with fiber
pulp.
9. An improved solar flat plate collector as claimed in any of the
preceding claims provided with a number of variants such as
herein described.
10. An improved solar flat plate collector substantially as herein
described with reference to the accompanying drawings.