Task+3_+DO

= Energy Efficiency of Popping Corn = = = = Task 3: DO =

In this task, you will need to analyze the energy efficiency of cooking popcorn using the stove (conduction) v.s the microwave (radiation). **All data needed is either given now or found in Task 1 reading.**

In your calculations you will need to:

> > > >  > > > The thermodynamic efficiency, e, of heat energy flow to carry out a process is defined as: > > ** e = what you get / what you pay for ** > > In the case of popping corn, the energy efficiency is a value for the joules of energy needed to produce a bowl of popcorn divided by the heat energy you must actually purchase to carry out the operation. The latter term includes the heat energy wasted into the room by inefficiencies of heat transfer. > > > >
 * 1) ** Evaluate the heat energy required for using conventional stove and microwave oven to popcorn. Use the chart given below to complete the calculations. Show your calculated result for each yellow box. **
 * 1) ** Calculate the actual electric energy consumption for both methods. You may use the chart below to help you. **
 * 1) **Calculate the efficiency of each method:**
 * 1) **Calculate the energy wasted (J) in each method.**
 * 1) **Time that a 100 W bulb could burn if all the wasted energy is used for that purpose.**
 * 2) **Discuss your findings and reflections in part (4) & (5). Also discuss where did the heat energy go? (Is it really wasted?)**
 * 1) **Research shows that in developed countries like Singapore, electricity generation is only 34% efficient with respect to the energy content of the fuels burned, compared with the electrical energy delivered to the home. Do a calculation of "overall" or "global" efficiency taking this indirect energy loss into account. Also calculate how many joules of energy must be obtained from natural resources to pop corn.**