Why is high air fuel ratio used in gas turbines?
The remaining air (tertiary air) continue to the mixing chamber (6) to be mixed with the gases from the flame tube and cool the final combustion products. Because of the high air-fuel ratio, combustor produce very little carbon monoxide and unburnt hydrocarbons.
What happens to the engine if there is an increase in the temperature of the air fuel mixture?
With the same oxygen concentration, the increase in the average temperature causes the rate of oxidation reactions to increase and the concentration of the unburned hydrocarbon emissions to be reduced. This is enhanced by further oxidation reactions in the exhaust manifold and the turbocharger.
What is the air fuel ratio of gas turbine?
Heat is added by combustion in the Gas turbines. In this process, energy is put into the system by burning fuel in flowing gas. The combustion is maintained in a stream of air moving with a high velocity in the region of 30-60 m/s. The air-fuel ratio vary from 60 : 1 to 120 : 1.
What does reheating in a gas turbine do?
Effect of reheating: This increases the work output of the turbine by keeping the compressor work constant. The mean temperature of heat rejection is also increased, resulting in a decrease in the thermal efficiency of the plant. For a given power output, the fuel consumption rate decreases.
Why high fuel air ratio is required during the high power mode of working of a carburetor in a SI engine?
This is because the air in the mixture provides the oxygen needed to burn the fuel completely. If the air is too little, then it provides inadequate oxygen for combustion. This results in unburnt fuel emitting the tail-pipe and going waste. If there is an excess of air, then it provides more oxygen.
What air fuel ratio is too rich?
Generally, the engine is considered to be running too lean when fuel trim is above 10\% (with the engine running in closed-loop mode). If fuel trim is below -10\%, the engine is typically considered to be running rich.
What is the air fuel ratio in gas turbine?
What does an air fuel ratio sensor do?
The air fuel ratio sensor is typically in the exhaust manifold or in the front exhaust pipe. It measures the oxygen in the exhaust and sends that information to the ECU. The ECU, based on the air-to-fuel ratio, adjusts the blend to keep it at the prime level. This level is generally 14.7:1.
What happens to the air fuel mixture in exhaust stroke?
Fuel Chemistry During the intake stroke, the fuel and air mixture is drawn into the cylinder with the exhaust valve closed. Then the air and fuel mixture is compressed in a compression stroke. At the top of the stroke, the spark plug ignites the mixture.
Why is the air fuel ratio in a gas turbine engine what it is?
Hi Michael— The air-fuel ratio in a gas turbine engine is what it is for the following reasons (s)— The equilibrium temperature of the combustion products is an unambiguous function of the air-fuel ratio. As the air-fuel ratio decreases, the combustion gas temperature increases.
What happens if the air fuel ratio is too high?
An excessively high air–fuel ratio may produce high pumping loss, high peak cylinder pressure, and high compressor outlet temperature. An excessively low air–fuel ratio may produce the problems of deteriorated combustion efficiency, high smoke, and high exhaust gas temperature.
Why is the temperature of a gas turbine engine high?
In addition, the place ‘on the curve’ of air-fuel ratio that gas turbines operate is such that temperature responds pretty strongly to air-fuel ratio. Normally, the combustion gas temperature in a gas turbine engine cycle is set as high as it can be, based on durability of various of the engine hardware— usually the nozzl
What causes a diesel engine to have a high exhaust temperature?
High exhaust gas temperatures are caused by too much fuel and too little air within the diesel motor’s cylinders. Facilitate the efficient consumption of fuel, and lowered exhaust temperatures, by allowing more clean air to flow into the motor and reset the appropriate air to fuel ratios. Click to see full answer.