Search results
Results from the WOW.Com Content Network
A heat engine is a system that converts heat to usable energy, particularly mechanical energy, which can then be used to do mechanical work. [1] [2] While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, particularly electrical, since at least the late 19th century.
1. Power piston, 2. Cold end of cylinder, 3.Displacer piston 4. Hot end of cylinder Q1. Heat in, Q2. Heat out. A hot air engine [1] (historically called an air engine or caloric engine [2]) is any heat engine that uses the expansion and contraction of air under the influence of a temperature change to convert thermal energy into mechanical work.
For the three examples given above: 1) Heat can be transferred from a region of lower temperature to a higher temperature in a refrigerator or in a heat pump. These machines must provide sufficient work to the system. 2) Thermal energy can be converted to mechanical work in a heat engine, if sufficient heat is also expelled to the surroundings.
The ideal Otto cycle is an example of an isochoric process when it is assumed that the burning of the gasoline-air mixture in an internal combustion engine car is instantaneous. There is an increase in the temperature and the pressure of the gas inside the cylinder while the volume remains the same.
For a heat engine, thermal efficiency is the ratio of the net work output to the heat input; in the case of a heat pump, thermal efficiency (known as the coefficient of performance or COP) is the ratio of net heat output (for heating), or the net heat removed (for cooling) to the energy input (external work). The efficiency of a heat engine is ...
According to the second law of thermodynamics, a heat engine can generate power from this temperature difference. In a CHP system, the high-temperature primary heat enters the Stirling engine heater, then some of the energy is converted to mechanical power in the engine, and the rest passes through to the cooler, where it exits at a low ...
Many authors like for example O. Badr et al. [3] have suggested the following thermodynamic and physical criteria which a working fluid should meet for heat engines like Rankine cycles. There are some differences in the criteria concerning the working fluids used in heat engines and refrigeration cycles or heat pumps, which are listed below ...
In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot "source" and a cold "sink". Heat is transferred to the sink from the source, and in this process some of the heat is converted into work. A heat pump is a heat engine run in reverse ...