when continuous monitoring indicates the readings have been within the maximum permissible limits. The ASME PTC-22-test code requires that the performance test will be run as much as possible to the design test conditions as specified in the contract. The maximum permissible variation in a test run shall not vary from the computed average for that operating condition during the complete run by more than the values specified in Table 20-2. If operation conditions vary during any test run vary by more than the pre-scribed values in Table 20-2 than the results of that test run shall be discarded. The test run should not exceed 30 minutes and during that time the interval between readings should not exceed 10 minutes. There shouldbe three to four test runs performed， which then could be averaged to get the final guarantee test points.
Correction factors are also provided in ASME PTC Test Code-46. Thecorrection factors for ambient temperature， ambient pressure， and relative humidity are presented in this chapter.
The equations and performance parameters for all the major components of a power train must be corrected for ambient conditions and certain parameters must be further corrected to design conditions to accuratelycompute the degradation. Therefore， to fully compute the performance， anddegradation of the plant and all its components， theactual， corrected， and transposed to reference conditions of critical parameters must be computed.
The overall plant needs the following parameters to be computed. The most important two parameters from an economic point of view are the computation of the power delivered and the fuel consumed to deliver
.02 Gas Turbine Engineering Handbook
the power. The following are the parameters that need to be computed to fully understand the macro picture of the plant.
1. Overall plant system
2. Gross unit heat rate
a. Net unit heat rate
b. Gross output
c. Net output
d. Auxiliary power
Gas Turbine
The ASME， Performance Test Code on Gas Turbines， ASME PTC 22 examines the overall performance of the gas turbine. The ASME PTC 22 only examines the overall turbine and many turbines in the field are better instrumented for computation of the detail characteristics of the gas turbine. Figure 20-6 shows the desired location of the measurement points for a fully instrumented turbine. The following are the various computations required to calculate the gas turbine overall performance based on the code:
1. Gas turbine overall computation
2. Gas turbine output
3. Inlet air flow
4. First stage nozzle cooling flow rate
. Total cooling flow rate
Figure 20-6. Gas turbine suggested measurement .oints.
6. Heat rate
7. Expander efficiency
8. Gas turbine efficiency
9. Exhaust flue gas flow
10. Specific heat of exhaust flue gas
To further analyze， the gas turbine must be examined in its four major categories:
1. Air inlet filter
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