Heat Dissipated vs Work Accomplished
We use electrical, mechanical or any other type of systems to get done some work. For example, we use the electrical equipment called ‘bulb’ to get light. In a bulb, electrical energy is converted into light energy (or to electromagnetic waves). However, all the electrical energy supplied into a bulb is not converted into light, although we wish it to be. Some of the electrical energy is converted into heat (which we do not want), and it is known as heat dissipation. The amount of energy that is actually converted into light (this is some percentage of the total energy supplied) is called the ‘work accomplished’.
Any dynamic system (electrical, mechanical or any other) dissipates some heat due to many reasons such as friction, impedance, turbulence etc. This is an unwanted, but unavoidable phenomenon according to the laws of thermodynamics. However, we can minimize the amount of heat dissipation through proper system design. For example, ‘power factor correction’ in electrical systems can reduce the heat dissipation to a greater extent.
In case of an incandescent bulb, heat is dissipated when the current is flowing through the filament. It emits not only desired light waves, but also heat. Heat dissipation is lower in CFL and LED bulbs compared to incandescent bulbs. According to the concepts such as ‘entropy’ and ‘Carnot cycle’ in thermodynamics, heat dissipation is unavoidable, though it can be minimized.
In a system, work accomplished is the energy that has been converted into what we need. For a bulb, it is the amount of light energy emitted from it. For a motor, it is the kinetic energy of the rotating part. For a television, it is light and sound energy emitted from it. The percentage of work accomplished to the total energy supplied is known as ‘efficiency’. Work accomplished is always less than the total energy supplied, as some amount of heat dissipation is unavoidable. Therefore, 100% efficient systems are impossible. Even a totally mechanical system, will dissipate some heat due to friction.
What is the difference between Heat Dissipated and Work Accomplished?
1. Work accomplished is the amount of energy converted into the desired output, where heat dissipation is the energy wasted as heat.
2. Work accomplished is the wanted part, and heat dissipation is unwanted.
3. Although unwanted, heat dissipation cannot be reduced to zero according to the laws in physics.
4. If the percentage of work accomplished to the total energy supplied is higher, the system is ‘high efficient’, where the system is ‘low efficient’ if the heat dissipation is higher.