Monday, February 4, 2008

SIAPV3.0, is a parabolic solar cooker.

SIAPv3 is a reflector type of solar cooker. It consists of a parabolic reflector and a cross rack to hold the cooking pot. The parabolic reflector is constructed using a 24dBi/2.4GHz parabolic grid antenna, dressed with aluminium foil.

The paraboloid measures 1000mm(L)x 600mm(W), has a focus located around 370mm from the centre was used as the reflector frame. Above the frame, aluminium foil was laid to turn it into a solar reflector.

The cross rack is made from a mix of 25mm dia aluminium and pcv tubes. The cross leg and the top frames are made of aluminium, whereas the bottom frames are made of pvc tube. Aluminium tube could provide the necessary mechanical strength and heat resistance, while the pvc tube provides the basis mechanical strength.

The cross legs are held in position using two tension frames. The tension frames are made of aluminum rail that are fitted with pvc u-clips. On each tension frame, one u-clip is fixed at the end and three u-clip are fixed on the other end, starting from 300mm from the he first unit, at 50mm interval.

The Pot and Platform

A stainless steel port with lid was used. This pot is covered with aluminium foil before it is sprayed with flat black (Anchor No 29) paint, likewise for the cover.

Gauge 18, GI wire mesh with grid size of 50mmx50mm, measuring 300mmx300m was placed on top of the cross leg to turn it into a platform for holding the pot.

The Experiment

During the test today, the rack and the reflector were placed in position before half a liter of water was poured into the pot, which contains 4 chicken eggs.

The reflector was laid flat against the floor surface. The height of the reflector was adjusted to ensure the focus is on the pot.

Observation and Results

The water inside the pot starts to heat up when the sky is clear with ample sunlight. However, when the sun is shaded by cloud, the pot cool off rapidly.

The reflector made of aluminium foil was not smooth and did not make a good reflecting surface. The chicken eggs fails to completely cook at the end of the experiment. It was about 80-90 cooked.

Conclusions and Recommendations
Lack of constant sun during the experiment causes the pot to repeat the heating and cooling process. The repeated heating and cooling of the pot is not conducive for the boiling of the chicken eggs inside. The highest temperature inside the pot measured 70C was not hot enough to boil the egg quickly.

The pot shall be insulated on the side and perhaps on the top to reduce heat loss. Mirror could be used in place of the aluminum foil as the reflecting surface to maximize the reflection. The focus of the reflector shall be established to ensure the pot is indeed sitting on the focus.

Report by Allen Liew 22/9/07 5:15 pm

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