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I'm working on estimating the necessary BBQ temperature to heat a 500-gram steak from 5°C (straight out of the fridge) to 50°C in one hour. Here's a brief overview of the problem:

Problem Description:

The steak starts at 5°C and needs to reach 50°C after one hour. The temperature of the meat will be measured using a meat thermometer. We are using a BBQ with a built-in thermostat and assume indirect grilling (the steak is not placed directly over the fire). Ideally, we want to keep the temperature inside the BBQ as steady as possible. Once the steak reaches 50°C internally, we take it out of the BBQ and wrap it in aluminum foil to let it rest, allowing the juices to redistribute (but that's another topic).

Back-of-the-Envelope Calculations:

  • To heat the steak, the required heat (Q) is calculated using:

    Q = mcΔT

    Where m is the mass (500 grams), c is the specific heat capacity (assumed to be 2.6 J/g°C ), and ΔT is the change in temperature (45°C).

    Q = 500gx2.6J/g°C×(50-5) °C = 58500J

  • To achieve this in one hour (3600 seconds), the required power (P) is:

    P= Q/t = 58500J/3600s = 16.25W

  • Using a heat transfer coefficient h of 10 W/m²°C for air, and estimating the surface area A of the steak as 0.015 m² and an average temperature of steak during heating T_avg (50-5)/2 = 22.5 °C, the convective heat transfer equation gives:

    Q = hA(T_bbq- T_avg)

    16.25 W = 10 W/m²°C x 0.015 m² x (T_bbq - 22.5 °C)

    108.3 = T_bbq - 22.5

    T_bbq = 131 °C

Request for Input:

  • Does this approach and the calculations seem reasonable?

  • Are there any adjustments or considerations I might be missing?

  • What practical BBQ temperature would you recommend for indirect grilling to achieve this temperature rise?

Thank you for your insights and advice!

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1 Answer 1

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If you're truly trying to cook a steak with no browning, smokey flavor, or grill marks it seems to me that a better approach would be the sous vide cooking method in which the food is sealed in a plastic bag which is immersed in a temperature-controlled water bath.

As far as the calculation goes, the approach is probably reasonable, but ii is limited by the implicit assumption that the steak is at uniform temperature when it actually will heat from the outside in. A better (though more complex) approach would be to calculate the temperature profile through the steak, and calculate the time for the center to reach the target temperature.

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