![]() Which is where we come in with this handy microwave conversion chart. Some microwaves offer multiple power rating outputs through their settings and so you may be able to adjust your particular machine to match the recipe but if not then you will need to convert the time. Now food is heated by microwaves at a rate roughly proportionate to the power output of the microwave and so if the microwave and recipe do not match then you will need to adjust the time of cooking for the same result. Then there is the additional problem of recipes designed for the modern microwave appliance of the 80’s and the power ratings available in those times, to modern recipes with higher ratings.Įven today, microwaves are sold with quite different power ratings so even a new microwave may not be the same rating as needed for the recipe you are reading. ![]() So we have some people using old microwaves with a maximum power rating of say, 600W and other people with later older models with power ratings of 700W or 750W and nowadays the more common 850W or 1100W or even 1200W ovens. A melting peanut cluster bar in an engineers pocket led to the creation of this technology marvel so many people have in their kitchens.īut the first kitchen microwaves were not the same as the ones we have today being quite a bit lower powered, gradually increasing in power as technology moves on. Not so long in the past, about 70 years ago actually, microwaves were not even imagined. So a microwave recipe for a microwave of a given power will need to be retimed for a microwave of different power. The waves are bounced off a metal reflective fan which disperses them into the food that heats up at a rate proportional to the power of the microwave. Separate calculations are thus required using Equation 1 for the material below and above the phase change temperature.If your microwave looks like this then you’ll need to convert modern recipe timings Why Microwave Recipes Need Time ConversionĪ microwave creates microwaves of differing strength depending on the power of the magnetron which creates them. The Cp value (from Equation 1) of a material also changes with a change in state. How much energy is required to melt 50 lbs of lead?Ĭhanging state (melting and vaporizing) is a constant temperature process. Hv = Latent Heat of Vaporization (Btu/ lb ) Q D = Heat Required to Melt/Vaporize Materials Processed in Working Cycle ( Wh ) Q C = Heat Required to Melt/Vaporize Materials During Heat-Up ( Wh ) This same amount of energy is released as the vapor condenses back to a liquid. The latent heat of vaporization Hv of the substance is the energy required to change a substance from a liquid to a vapor. Another state change is involved in vaporization and condensation. The heat needed to melt a material is known as the latent heat of fusion and represented by Hf. Heat Required to Melt or Vaporize a Material In considering adding heat to a substance, it is also necessary to anticipate changes in state that might occur during this heating such as melting and vaporizing. How much heat energy is needed to change the temperature of 50 lbs of copper from 10☏ to 70☏? Heated media, work being processed, vessels, racks, belts, and ventilation air should be included. This equation should be applied to all materials absorbing heat in the application. ∆T = Temperature Rise of Material ( T Final – T Initial )(☏) Q B = Heat Required to Raise Temperature of Materials Processed in Working Cycle ( Wh ) Q A = Heat Required to Raise Temperature of Materials During Heat-Up ( Wh ) Since all calculations are in watts, an additional conversion of 3.412 Btu = 1 Wh is introduced yielding: ![]() Calling the amount of heat added Q, which will cause a change in temperature ∆T to a weight of substance W, at a specific heat of material Cp, then Q =w The specific heat capacity of a substance is the quantity of heat needed to raise the temperature of a unit quantity of the substance by one degree. ![]() Absorbed Energy, Heat Required to Raise the Temperature of a Material Because substances all heat differently, different amounts of heat are required in making a temperature change.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |