The correction curves of heat capacity ratio of flue gas flow rate are necessary in heat transfer efficiency calculation for rotary air preheaters according to the PTC 4.3

but it is difficult to obtain. In this paper

an approximate method was proposed

which does not require the correction curves. On the basis of the effectiveness-NTU(number of transfer units) method

this method analyzes a large number of design parameters of air preheaters covering a variety of coal qualities and capacities

and obtains the relationship between the efficiency of air preheater and the heat-capacity ratio of flue gas flow and air flow with different heat transfer units

then it establishes the calculation model for heat transfer efficiency of air preheaters. Finally

this method was applied to calculate the heat transfer efficiency of air preheaters in a power plant

the results are consistent with the design and actual operation situations

indicating this method is relatively accurate.