# Heat Engine Research Paper

984 Words4 Pages
Efficiency of Heat Engines Thermodynamics and the history of heat engines Thermodynamics is the branch of physics that is involves the change in state properties such as temperature, volume, pressure and their relation to heat transfer, energy, and work. The first law of thermodynamics states that energy can neither be created nor destroyed, it can only be transferred. The second law of thermodynamics states that the entropy of any isolated system not in thermal equilibrium always increases. The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero. The most significant heat-engine development was that of the steam engine. When the mathematician and inventor Hero…show more content…
These processes are common in heat engines as well. One of the processes is the isobaric process this is a process that happens at constant pressure. Another thermodynamic process is the adiabatic process this is where the work done on the system is equal to the internal energy with no heat flow. An isothermal process has an internal energy of zero this means that the external heat is equal to the work done by the system. The isometric process happens at constant volume this means that no work is done on. An isothermal process occurs at a constant…show more content…
An intake stroke happens at point ‘4’. The piston descends with one of the inlet valves open receiving combustible mixture. Both the valves are then closed and the compression on the gas from ‘4’ to ‘1’ both the pressure and the temperature increase. The combustion stroke happens at point ‘1’. The combustion stroke is started by a spark which gives heat hence causing the pressure to increase at a constant volume till point ‘2’. The exhaust stroke happens between points ‘3’ and ‘4’. The piston ejects the burnt gas through an open outlet valve. The efficiency of the Otto cycle is n=1-1/r^(ɣ-1) where r is equal to v1/v2 also known as compression ratio. The Diesel engine was developed by Rudolf Diesel. It is similar to the Otto cycle with one of the differences being that the engine takes in air rather than combustion mixture. The diagrams below demonstrate the cycle of a diesel engine. The processes are the same except that the combustion stroke is an isobaric process rather than an isometric one as seen in the Otto