CN105184043A - Condenser heat transfer coefficient calculation method based on single non-dimensional number - Google Patents
Condenser heat transfer coefficient calculation method based on single non-dimensional number Download PDFInfo
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- CN105184043A CN105184043A CN201510410557.7A CN201510410557A CN105184043A CN 105184043 A CN105184043 A CN 105184043A CN 201510410557 A CN201510410557 A CN 201510410557A CN 105184043 A CN105184043 A CN 105184043A
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Abstract
The invention discloses a condenser heat transfer coefficient calculation method based on a single non-dimensional number, which relates to the technical field of turbo generator sets and solves the technical problem of difficulty in determination of condenser heat transfer coefficient in the existing method. The method provided by the invention comprises the following steps of: firstly defining a non-dimensional number, and building a relation between the non-dimensional number and the condenser heat transfer coefficient; fitting a relation between a cooling water flow related coefficient and the cooling water flow through a polynomial fitting method; and calculating a condenser normal heat transfer coefficient under the current working condition. The method provided by the invention is suitable for the condensing turbo generator sets.
Description
Technical field
The present invention relates to turbodynamo group technique, particularly relate to a kind of technology of the condenser heat transfer coefficient calculating method based on single dimensionless number.
Background technology
Condenser and backup system thereof are Turbo-generator Set cold junctions, and the operation of its running status to Turbo-generator Set is significant, and the research and apply therefore about condenser operational diagnostics and optimization is paid attention to always widely.The key issue of condenser operational diagnostics and optimization is the coefficient of heat transfer (heat exchange thermal resistance) that should reach under determining operating states of the units.
The defining method of current condenser heat transfer coefficient has following three kinds:
1) theoretical calculation method
The basic diabatic process of condenser is the outer condensation heat of pipe, tube wall heat conduction and the interior convection heat transfer' heat-transfer by convection process of pipe.Therefore, single tube condenser overall heat transfer coefficient is the inverse of entire thermal resistance in theory, so the normal heat transfer coefficient of condenser
can be expressed as:
Wherein,
,
for heat exchanger tube external diameter, internal diameter,
for water side coefficient of convective heat transfer,
for steam side condensing coefficient,
for cooling the coefficient of heat conductivity of tube wall,
for the length of pipeline;
In reality, condenser is the complex combination of many heat exchanger tubes, at the different sections of condenser heat-transfer surface, because steam parameter, relative air content, cooling water parameter are not identical with the spread pattern etc. of local cooling tube, in each section of condenser, heat exchange state is not identical yet, and the heat exchange models of single tube obviously can not describe the heat exchange of actual condenser.
2) engineering calculating method
Due to the deficiency of theoretical method, condenser heat transfer coefficient is determined often through experimental formula, the other Germania experimental formula of what at present application was wider is formula that U.S. thermal conduction study meeting (HEI) recommends, USSR (Union of Soviet Socialist Republics) thermal technology institute and Britain BEAMA formula in engineering.
But above-mentioned experimental formula computing method all fail to consider that actual Cooling Tubes of Condenser bundle is arranged and the impact of vapour side air leakage and cleanliness factor change, also there is certain error in therefore calculating for concrete unit.
3) method is determined in test
Also condenser heat transfer coefficient is determined by test method: according to the regulation of " Turbine Performance Test code " and " condenser performance test code " in engineering, measure the Specifeca tion speeifications such as the circulating water flow under different unit load, condenser pressure, cooling water inlet temperature and outlet water temperature, by to table look-up or the mode of software obtains the recirculated water density under each operating mode and the saturation pressure under condenser pressure, and then try to achieve condenser overall heat transfer coefficient.
But condenser performance test is comparatively complicated, operation inconvenience, therefore can only determine the heat transfer coefficient of limited operating mode, can not obtain condenser heat transfer coefficient under each operating mode required for optimizing process, therefore this kind of method has limitation in actual applications.
In sum, have method to determine the heat transfer coefficient of condenser, the unit that reality is determined for certain although actual from theory to engineering, under any operating mode, its normal heat transfer coefficient is still difficult to conveniently, accurately, fast determines.
Summary of the invention
For the defect existed in above-mentioned prior art, technical matters to be solved by this invention is to provide a kind of condenser heat transfer coefficient calculating method based on single dimensionless number quickly, accurately and conveniently determining the normal heat transfer coefficient of condenser under any working condition.
In order to solve the problems of the technologies described above, a kind of condenser heat transfer coefficient calculating method based on single dimensionless number provided by the present invention, relate to condensing steam turbine generator group, it is characterized in that, concrete steps are as follows:
1) defining a dimensionless number is:
Wherein,
for the dimensionless number of condensing steam turbine generator group,
for the load of condensing steam turbine generator group,
for the cooling water flow of condensing steam turbine generator group,
for the chilled water specific heat capacity of condensing steam turbine generator group,
for the cooling water inlet temperature of condensing steam turbine generator group;
2) pass defined between dimensionless number and the normal heat transfer coefficient of condenser is:
Wherein,
the normal heat transfer coefficient of condenser for condensing steam turbine generator group,
be cooling water flow related coefficient;
3) polynomial fitting method matching cooling water flow related coefficient is adopted
with cooling water flow
relation, and cooling water flow related coefficient
with cooling water flow
relation, obtain cooling water flow related coefficient
with cooling water flow
relational expression be:
Wherein,
for cooling water flow related coefficient
the quantity of match point,
for cooling water flow related coefficient
the quantity of match point,
be the cooling water flow of i-th match point,
for the cooling water flow of a jth match point,
for determining
i-th multinomial coefficient,
for determining
i-th multinomial coefficient;
4) load of condensing steam turbine generator group under current working is obtained
, cooling water flow
, chilled water specific heat capacity
, cooling water inlet temperature
;
5) dimensionless number under current working is first calculated, and according to the cooling water flow related coefficient that step 3 obtains
with cooling water flow
relational expression, calculate the cooling water flow related coefficient under current working
;
Again according to step 2 define dimensionless number and the normal heat transfer coefficient of condenser between relation, calculate the normal heat transfer coefficient of condenser under current working
.
Condenser heat transfer coefficient calculating method based on single dimensionless number provided by the invention, the normal heat transfer coefficient of the condenser of condensing steam turbine generator group under any operating mode is determined by a dimensionless group, there is convenience of calculation, accurately and rapidly feature, only need to measure other operating mode that limited operating mode just can be generalized to this unit, make the judgement of condenser working condition more simple.
Accompanying drawing explanation
Fig. 1 is the structural representation of the condensing steam turbine generator group involved by the embodiment of the present invention.
Embodiment
Illustrate below in conjunction with accompanying drawing and embodiments of the invention are described in further detail; but the present embodiment is not limited to the present invention; every employing analog structure of the present invention and similar change thereof, all should list protection scope of the present invention in, the pause mark in the present invention all represent and relation.
A kind of condenser heat transfer coefficient calculating method based on single dimensionless number that the embodiment of the present invention provides, relate to condensing steam turbine generator group, it is characterized in that, concrete steps are as follows:
1) defining a dimensionless number is:
Wherein,
for the dimensionless number of condensing steam turbine generator group,
for the load of condensing steam turbine generator group,
for the cooling water flow of condensing steam turbine generator group,
for the chilled water specific heat capacity of condensing steam turbine generator group,
for the cooling water inlet temperature of condensing steam turbine generator group;
2) pass defined between dimensionless number and the normal heat transfer coefficient of condenser is:
Wherein,
the normal heat transfer coefficient of condenser for condensing steam turbine generator group,
be cooling water flow related coefficient;
3) adopt test method(s) to measure the operational data of condensing steam turbine generator group under various working, and calculate the dimensionless number of condensing steam turbine generator group under each operating condition of test and the normal heat transfer coefficient of condenser;
In test, the cooling water flow of employing has at least two kinds, and often kind of cooling water flow at least adopts in two kinds of operating condition of test;
The computing formula of the normal heat transfer coefficient of condenser is:
Wherein,
the normal heat transfer coefficient of condenser for condensing steam turbine generator group,
for the cooling water flow of condensing steam turbine generator group,
for the chilled water specific heat capacity of condensing steam turbine generator group,
for the condenser heat interchanging area of condensing steam turbine generator group,
for the saturation temperature of condensing steam turbine generator group,
for the cooling water inlet temperature of condensing steam turbine generator group,
for the cooling water outlet temperature of condensing steam turbine generator group;
According to test figure, adopt polynomial fitting method matching cooling water flow related coefficient
with cooling water flow
relation, and cooling water flow related coefficient
with cooling water flow
relation, obtain cooling water flow related coefficient
with cooling water flow
relational expression be:
Wherein,
for cooling water flow related coefficient
the quantity of match point,
for cooling water flow related coefficient
the quantity of match point,
be the cooling water flow of i-th match point,
for the cooling water flow of a jth match point,
for determining
i-th multinomial coefficient,
for determining
i-th multinomial coefficient;
4) load of condensing steam turbine generator group under current working is obtained
, cooling water flow
, chilled water specific heat capacity
, cooling water inlet temperature
;
5) dimensionless number under current working is first calculated, and according to the cooling water flow related coefficient that step 3 obtains
with cooling water flow
relational expression, calculate the cooling water flow related coefficient under current working
;
Again according to step 2 define dimensionless number and the normal heat transfer coefficient of condenser between relation, calculate the normal heat transfer coefficient of condenser under current working
.
The structural representation of the condensing steam turbine generator group of Fig. 1 involved by the embodiment of the present invention, as shown in Figure 1, during the work of condensing steam turbine generator group, steam 1 enters steam turbine 2 expansion work drive electrical generators 3 and generates electricity, steam discharge enters condenser 12, cooled water cooling becomes condensate water 11, and chilled water leaves condenser 12 by coolant outlet pipeline 7 after heating up; The transmission line of electricity 5 of generator is installed the load that the first measuring point 4 can measure condensing steam turbine generator group, the cooling water inlet pipeline 8 of condenser is installed the second measuring point 9, cooling water inlet temperature can be measured, the 3rd measuring point 10 installed by the cooling water inlet pipeline 8 of condenser, cooling water flow can be measured, the measured value of three measuring points is sent into computing unit 6, according to the computation model of the normal heat transfer coefficient of condenser and dimensionless number, can calculate and determine the normal heat transfer coefficient of condenser under this operating mode.
The computing method of the embodiment of the present invention have carried out illustration by the condenser of 330MW Turbo-generator Set, and the supporting condenser model of this Turbo-generator Set is N-16300-1, and film-cooled heat is 16300 ㎡, and its cooling water flow only has two kinds;
Adopt test method(s) to measure the service data of condenser under 5 operating modes of Turbo-generator Set, and calculate the dimensionless number under 5 operating modes
the normal heat transfer coefficient of condenser
, concrete data are as shown in table 1;
Table 1
Foundation
power function relationship matching
with
relational expression as shown in table 2;
Table 2
| （m3/s） | Fit correlation formula | ||
| 9.8125 | =2.7893( )-0.1021 | 2.7893 | -0.1021 |
| 9.2125 | =2.2757( )-0.203 | 2.2757 | -0.203 |
Owing to only having two kinds of flows, therefore cooling water flow related coefficient
it is cooling water flow
linear function, fit correlation is as follows:
Then
with
relational expression be:
In unit running process, when calculating the normal heat transfer coefficient of condenser under current working, the service data according to measuring point records: the load of condensing steam turbine generator group is 270MW, and cooling water flow is 9.8125m3/s, and cooling water inlet temperature is 33.65 DEG C;
Then:
（kW/m2·℃）。
Claims (1)
1., based on a condenser heat transfer coefficient calculating method for single dimensionless number, relate to condensing steam turbine generator group, it is characterized in that, concrete steps are as follows:
1) defining a dimensionless number is:
Wherein,
for the dimensionless number of condensing steam turbine generator group,
for the load of condensing steam turbine generator group,
for the cooling water flow of condensing steam turbine generator group,
for the chilled water specific heat capacity of condensing steam turbine generator group,
for the cooling water inlet temperature of condensing steam turbine generator group;
2) pass defined between dimensionless number and the normal heat transfer coefficient of condenser is:
Wherein,
the normal heat transfer coefficient of condenser for condensing steam turbine generator group,
be cooling water flow related coefficient;
3) polynomial fitting method matching cooling water flow related coefficient is adopted
with cooling water flow
relation, and cooling water flow related coefficient
with cooling water flow
relation, obtain cooling water flow related coefficient
with cooling water flow
relational expression be:
Wherein,
for cooling water flow related coefficient
the quantity of match point,
for cooling water flow related coefficient
the quantity of match point,
be the cooling water flow of i-th match point,
for the cooling water flow of a jth match point,
for determining
i-th multinomial coefficient,
for determining
i-th multinomial coefficient;
4) load of condensing steam turbine generator group under current working is obtained
, cooling water flow
, chilled water specific heat capacity
, cooling water inlet temperature
;
5) dimensionless number under current working is first calculated, and according to the cooling water flow related coefficient that step 3 obtains
with cooling water flow
relational expression, calculate the cooling water flow related coefficient under current working
;
Again according to step 2 define dimensionless number and the normal heat transfer coefficient of condenser between relation, calculate the normal heat transfer coefficient of condenser under current working
.
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Cited By (1)
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| CN114544210A (en) * | 2022-01-11 | 2022-05-27 | 国能浙江宁海发电有限公司 | Method for testing heat transfer performance attenuation of condenser |
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