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Hello everyone,
I prepare my first article (gas turbine modelling) in english language to register for PhD conferment procedure, and because I am not an englishman, I am sure the grammar/writing style is not too good. Some part is already "polished" by a friend of mine, but has no time to do the rest. I am kindly asking anybody who has some spare time to take a look at the following text and correct: (It is very technical, but it is not necessary to understand this to do editing)
Available catalogue gas turbine units data include following entities: frequency, electrical power, electrical efficiency, pressure ratio, exhaust gas mass flow rate and temperature after diffuser. These parameters are insufficient to carry out a simulation of turbine operation, therefore values of missing parameters have to be estimated. List of parameters used as an input data in developed model of gas turbine unit, with missed values estimation difficulty, contains table no 1.
Values of pressure ratio and exhaust gas mass flow ratio have to be taken from catalogue, whereas electric power, electric efficiency and exhaust gas temperature after diffuser are calculated values. After initial assumption of unknown input parameters, they have to be corrected to achieve electric power, electric efficiency and exhaust gas temperature after diffuser, close to real (given by the producer). To facilitate correction of this parameters, the following relative errors (deviations) are given: ...
Furthermore, fuel mass flow rate relative error is calculated, which is used to determine the mean temperature of the combustion, so its correction ought to be done in the first instance. Because flame has different temperatures depending on its zone, we operate on the mean combustion temperature. Relative error of fuel mass flow rate: ...
Real fuel mass flow rate is calculated from transformed electric efficiency formula: ...
That mass flow rate is calculated with an assumption, that gas turbine unit is fuelled by pure methane, which is the main component of natural gas, hence star in the index. As a fuel, in all calculations, to simplify it is taken high-methane natural gas reduced only to methane.
It has to be realized/We need to be aware of that gas turbine units catalogue data given by producers have only informative character, and do not oblige them to reach presented values of parameters.
Pressure losses after the turbine side have been/were defined as a difference between atmospheric pressure and pressure in the end point of combustion gas expansion, and they consist of losses on the diffuser and losses on HRSG: ...
In the first stage of simulation we endeavour to reach the greatest convergence with catalogue parameters (el. power, el. efficiency, temperature after diffuser), which are given for gas turbine unit operating in simple cycle, therefore HRSG pressure losses shouldn’t be taken into consideration. Absolute deviation values of all considered comparative parameters should be as small as possible and close to others. After correction of input parameters and fixing their values, we can set backpressure caused by HRSG, what will result in gas turbine unit power and efficiency decrease and combustion gas temperature after turbine.
Instead of isentropic efficiency of compressor and turbine, it was decided to take their polytropic efficiencies, which unlike isentropic can be find constant, do not changing with change of pressure ratio. Owing to this, model can be utilized to simulate gas turbine unit in different pressure ratio values and in searching of optimal pressure ratio.
Thanks in advance for help. I will be grateful.
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