Fig. 5. Temperature and radiation values for F2 analysis
4. Calculating Cooking Power
The most representative merit figure in thermal efficiency is the Effective Cooking Power (ECP). To calculate ECP, we followed IANSC protocols (Esteves, 2001 [16]):
- Cooking power is the difference in water temperature every five minutes, multiplied by mass and the water specific heat, calculated for the range between 40 °C and the boiling point minus 5 °C (91 °C). This product is divided by 300 s, yielding the ECP in W.
- Plotting and regression are displayed in two graphs. Fig. 5 plots the water temperature against time, and Fig. 6 plots cooking power at various temperature intervals.
- To standardize cooking power, a standard solar radiation of 700 W/m2 was corrected by multiplying the observed power by 700 W/m2 of radiation and dividing the product by the average recorded temperature during the corresponding interval.