Microwaves penetrates food products and the heating extends within the entire product.
Packaging materials such as glass, ceramics and most thermoplastic materials allows microwaves to pass with little or no absorption.
The relation wavelength, frequency and velocity of electromagnetic waves:
λ = c / f (1)
λ = wavelength (m)
c = speed of light (3 108 m/s)
f = frequency (Hz, 1/s)
Permitted frequencies for microwave ovens
- 915 +- 13 Mhz
- 2450 +- 50 Mhz
The wavelengths can be calculated as
λ1 = (3 108 m/s) / (915 106 1/s)
= 0.328 (m)
λ2 = (3 108 m/s) / (2450 106 1/s)
= 0.122 (m)
Work, heat and energy systems.
Typical power consumption and running time for common electrical equipment.
The electromagnetic spectrum with wavelengths and frequencies.
Energy in carbohydrates, fats and proteins.
pH in common food products - like apples, butter, wines and more.
Specific heat of common food and foodstuff like apples, bass, beef, pork and many more.
Bulk densities of some common food products like grain, corn, barley, sugar and more.
Osmotic pressure in food products.
Absolute (dynamic) viscosity for common food products.
Common bacteria and viruses found in food.
Thermal conductivity of selected foodstuff like apples, beef, sugar and more.
Thermal diffusivity of some selected food products.
Heat loss from electrical equipment like switch-gear, transformers and variable frequency drives.
Water content before and after drying - in food and other products cork, grain, soap, peat, wood and more.