My objective is to heat a liquid inside a bottle. I have a air gap of 2 cm between the bottle and the heating element (resistive layers). The heater and the bottle is surrounded by a bottle insulator, so the volume of air to heat is fixed.
I did the calculation to know how many power I need in order to heat my liquid from 18°C to 37.5°C in 5 minutes with these formulas, taking into consideration weigh of the bottle, delta temperature and specific heat of glass material.
Q = cp * m * dt
- Q is heat required (kJ)
- Cp = specific heat (kJ/kg K, kJ/kg°C)
- Weight of bottle and liquid inside (kg) = 750 g
Then I deduced power needed: P = q / t
- P = power (kJ/s, kW)
- T = time (s)
P = 9.75W
My questions now are:
- How can I calculate the thermal dissipation between my heater physical element and my bottle of liquid as I have a air gap of 2 cm between both elements
- How can I deduce the real power I need with my heater element to be able to heat my liquid ?
- What is for you the best solution to heat my liquid in term of heater technology ?
I looked on google and I was able to determine my R factor for the whole assembly = 0.5 (due to air which is playing as insulator). But it's really hard to understand how to do this calculation and the steps of the calculation...
Can you help me ?