The product: technical properties





Goals

The aim of the technical tests is to know whether the Fortune Cooker functions technically. Therefore, we did technical tests on the heat input and heat loss of the prototypes. The Fortune Cooker’s initial goal is to maintain 100 degrees in the pan after turning off the heat resource. In ‘Function Analysis of the Fortune Cooker’ of the project plan (Appendix 4), the additional technological requirements that the Fortune Cooker should fulfil have been described. These are as follows:

  1. The product should be able to accommodate the placement of food.
  2. The amount of food able to be placed should be enough to feed an average Moroccan family (5 to 8 people)
  3. In case of an open heat source: it should always be possible to place the food above the heat source.
  4. The product should be able to accommodate the heat source
  5. There should be fresh air supply to the heat source
  6. The heat source should be as ‘climate-friendly’ as possible.
  7. The product should compensate the loss of warmth
  8. The product should be able to be fully closed
  9. Loss of heat should primarily be compensated by energy from sunlight
  10. Loss of heat should secondarily be established by the insulation of the product.
  11. All the parts of the product that can reach a temperature higher than 50 degrees Celsius should be made of heat resistant material.

Requirements 1, 2, and 4 are mainly important when building and designing new prototypes, and will therefore be discussed further along in this chapter. Requirement 3 however, should be tested by carrying out the technical tests described in the test plan below. In this way it can be established whether requirement 3 is being fulfilled, and if not, what the cause of that might be.

Test plan

As was described in the complete function analysis of the Fortune Cooker, the amount of energy that escapes the solar box should equal or less than the amount of solar energy that is collected. This means that once the pan (and its contents) in the Fortune Cooker has reached the desired temperature, the solar cooker should be able to maintain this temperature. The amount of energy lost and the amount of energy collected can be defined by measuring and calculating them separately. By defining these two quantities, the aspects on which the Fortune Cooker needs to be improved to function technically can be identified.

The heat loss is tested by placing a closed prototype out of the sun and subsequently measuring how long the water in the pan (2 litres) takes to cool down from 100 degrees to 70 or 60 degrees. With this data, the amount of lost Watts can be calculated.

The heat input is tested by putting the prototype optimally in the sun, which means that the prototype is turned parallel to the sun’s direction, and that the mirror is put in such an angle that as much sunlight as possible falls in the solar box. This position should be checked on from time to time, in order to keep it optimally placed. Then the temperature of the water in the pan (2 litres) is measured over time. With these measurements, calculations are made on the amount of Watts that the box collects from the sun.

Technical functionality vs. user needs

Seeing that in this point of the process, the user needs had not been completely specified yet, it is possible that the minimal technical requirements the Fortune Cooker should live up to, are not in line with the technical requirements that derive from the user needs. Therefore, it is possible that – if user specified requirements are indeed more strict – the prototype should be changed, and that some technical tests have to be performed again.