Dual Parabolic Dishes on Equatorial mount: Difference between revisions

Introduction

The most famous and most successful solar solar concentration system in the world is the Scheffler solar kitchen. They are great because the cooking or heat storage container is stationary and only the reflective dish moves. This is because the reflector and the target are on the axis of rotation on equatorial mount. This also reduces "tracking" costs hugely because the reflector just has to rotate at 15 degrees per hour and it will keep the reflected light on the target all day. To account for seasonal changes in in the path of the sun the reflector must change shape depending on the time of year. That is the hard part! It requires skilled engineering input which ups the cost and which may not be available locally in poor areas. A negative point with the Scheffler dishes is that they concentrate a significantly smaller area of light in winter than they do in summer. I tried a lower tech fixed shape dish as an alternative a few years ago and it was only slightly successful. Its biggest problem is that the center of gravity of a single dish moves off the axis as you adjust it for the seasons. This makes it harder to turn it depending on the time of year. NOT good! This is by way of introduction to the 2 dish alternative. If you have 2 equal sized "half" parabolic dishes on equatorial mount, and you have their centers of gravity on the axis of rotation at equinox, as you seasonally adjust one, your seasonal adjustment of the second one cancels out the center of gravity change of the first one! I have the model showing them in a rectangular frame for ease of turning and easy of set up to equatorial mount position. Please note that both targets are stationary so this means that solar fridges, water heating, stirling engines, box cookers,etc are potential interchangeable options at both focal points. The rectangular frame could be made to rotate on a large "Pipe" at both ends instead of a narrow axle. That would allow easy access to quite large interchangeable equipment at the 2 focal points. Above is a picture of a model of this idea. The model can be changed to show how equatorial mount changes depending on your location on earth. An actual installation would be simpler than the model because your latitude is known. Below is an attempt to draw it with the bicycle rims at both ends to easily rotate it.