#WATTAGE TEMPERATURE CONVERSION HOW TO#

You need to calculate the energy required to melt it. Or, in the case of boiling a liquid, the equation reads:Į PhaseChange = Latent Heat of Vaporization x WeightĬontinuing the example, assume the latent heat of fusion of Alloy ABC is 100 BTU/lb and it weighs 6 lb. Moreover, there is additional energy required to “push” the material from one state to another and is calculated as follows:Į PhaseChange = Latent Heat of Fusion x Weight A second calculation is performed from 200 to 300 oF using the specific heat for Alloy ABC in a liquid state. In this case, the wattage requirement is calculated from ambient (70 oF) to the melting point (200 oF) for Alloy ABC using the specific heat for Alloy ABC as a solid. The wattage requirement of heating the container is calculated as shown above, but the heating of Alloy ABC must be done in two parts. Contained in the vessel being heated is a mass of Alloy ABC, which melts at 200 oF. Imagine a system that is heated from 70 to 300 oF. If the system being heated contains material that will pass through a phase change (melt or boil), the calculations are slightly more complex and have to be broken into parts, but they follow the same rules. If the temperature needs to be reached faster, say in a half-hour, then the wattage requirement would be doubled. Because wattage requirements are calculated based on one-hour increments, the requirements for faster or slower heat-up times are calculated proportionally. This means that it will require 86.8 W of power to raise the temperature of a 23 lb block of tin from 70 to 300 oF in one hour.

Therefore:Į Initial = 23 lb x 0.0164 W-hr/lb oF x 230 oF Knowing that 1 BTU equals 0.2930711 W-hr, the specific heat of tin also can be written as 0.0164 W-hr/lb oF.

In this case, suppose you wanted to calculate the energy required to raise a 23 lb block of tin from an ambient temperature of 70 oF to 300 oF, given that the specific heat of tin is 0.056 BTU/lb oF. The energy (E) required to raise the temperature of a material by ΔT is calculated using the following formula:Į Initial = Weight of Material x Specific Heat of Material x ΔTĪn example will help demonstrate, so I will use examples throughout.

In the simplest case, a block of material is heated in more complex situations, calculations for multiple materials must be performed. All system components must be considered. The first calculation involves determining the heat required to raise the system temperature to the desired temperature. If a process is started at room temperature, say 80 oF, and the application process temperature is 800 oF, then ?T is 800 oF minus 80 oF, or 720 oF. It also should be noted that the difference between the starting temperature and the final temperature during the application of power commonly is referred to as delta T (ΔT). In English units, energy is measured in British thermal units (BTUs) and power is measured in BTU/hr. In metric units, power is measured in watts (W) and energy is measured in watts multiplied by hours (W x hr). Heat losses to the environment due to conduction, convection, and radiation.īefore beginning the calculations, it is important to realize the distinction between energy and power and their relationship to wattage requirements.Heating of material flowing through the process such as a liquid that will be heated and pumped to be used elsewhere.Heating of material being processed during operation.Losses due to materials changing phase, either during initial heat-up or while processing (melting a solid to a liquid or boiling a liquid to a gas).Initial heat for startup of the system, usually from ambient temperature to the desired processing temperature.Heat requirements that must be considered are:

#WATTAGE TEMPERATURE CONVERSION HOW TO#

Follow this step-by-step process to learn how to size a heating system for your process application.Ĭalculating the wattage requirements to heat a system is a straightforward process as long as all the possibilities of heat energy flowing in and out of the system are considered.

Wattage temperature conversion