Heat Loss in a Cook Pot at Constant Temperature

Heat Losses in a Cook Pot at Constant Temperature (pdf)
Alan Berick, Aprovecho June 10, 2006

Berick PotBerick Pot

During simmering or cooking the task of the cook stove is to maintain a constant cooking
temperature in the pot. In order to accomplish this goal, enough fuel is used to offset the energy losses from the pot.

These energy or heat losses are due to three main mechanisms; evaporation, radiation and
convection. The goal of this study is to quantify the relationship of these mechanisms and to attempt to find means to minimize these losses when possible.

Summary and Conclusions

For a 25 cm diameter pot:

  • At typical cooking temperatures, evaporation accounts for the major portion of the total heat losses.
  • At a temperature of 98° C evaporation accounts for approximately 78% of the heat loss for the blackened pot and 85% of the loss from the shiny pot.
  • A thin layer of cooking oil will entirely eliminate liquid evaporation.
  • This not only saves approximately 80% of the fuel used and reduces air pollution by the same amount, but >will also save water. At a cooking temperature of 98° C with 5 liters of water approximately 22.5% of the water is lost each hour.
  • Using a lid while cooking will achieve roughly 90% of the above savings as long as the lid is not removed during the cook time.
  • The heat loss from radiation accounts for 16 % of the total loss for the blackened pot and 8% of the total loss for the shiny pot.
  • Convection losses only account for 6% of the total for both pots.
  • A quick calculation of thermal efficiency for the electric range used in this study gave a value of 67%.

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