WHAT IS ADIABATIC ENGINE?
ADIABATIC ENGINE
An adiabatic process is one in which there is no heat added or removed from an isolated system.
Heat is not transferred into or out of the system.
The amount of work done by the process is therefore equal to the total change in energy.
In an intarnal combustion engine the engine is the system.
There is work done on the system and by the system.
There is also heat transfer from the engine to the environment, through the coolant system.
A system where the adiabatic process is employed to a certair extent is the adiabatic engine.
In theory the adiabatic engine has no heat loss. The change in energy for the system which is the diesel engine, is due to work done by the engine and work done on the engine.
Some advantages of the adiabatic engine are described below.
➝The removal of cooling water along with the radiator, fan, and water pump have made the adiabatic engine more cost effective.
➝The increase in temperature due to the slating ceramic material has increased the fuel economy.
➝Reductions in NOx, unburned hydrocarbons, and carbon monoxide is also expected.
➝The density of ceramics is lower than that of metals so the new engine is more lightweight therefore increasing fuel economy.
ADIABATIC DIESEL ENGINE
In practice it is impossible to have a 100 % adiabatic engine . At best the engine can reach 50-60 % of adiabatic with advanced ceramics.
In many cases the adiabatic engine is called the low heat rejection engine(LHRE), which more accurately describes the technology avaiable today.
As described earlier in an adiabatic enginc there is no heat added or rejected.
Theoretically one would like to mako use of the exhaust that is released by the enginc.
The use of a turbocharger idealized the no heat rejected concept by taking the high temperature exhaust and transferring, work to the engine.
The adiabatic diesel engine with waste heat utilisation is a very rewarding concept since there is energy being extract from the hot exhaust gases.
The brake fuel consumption is reduccd because of the following.
➝Insulation of the combustion chamber, exhaust and intake ports, and the exhaust manifolds.
➝Elimination of the cooling system and the associated parts.
➝Waste exhaust heat utization by turhocharging.
The advantages of using an adiabatic turbocharged diesel engine are:
➝Reduced fuel consumption
➝Reduced emissions and white smoke .
➝Multi-fuel capability Reduced noise level
➝Improved reliability and reduced maintenance
➝longer life
➝smaller installed volume
➝Lighter weignt
Problems with adiabatic engine
Some of the problems with the production of the adiabatic engine are as follow.
➝high temperature tribology
➝insulating ceramics
➝low cost fabrication
➝low cost
➝finishing and machining
➝Quality control methods.
