CN114372321A - Temperature design method for water interlayer shell of double-screw compressor - Google Patents

Temperature design method for water interlayer shell of double-screw compressor Download PDF

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CN114372321A
CN114372321A CN202111523459.6A CN202111523459A CN114372321A CN 114372321 A CN114372321 A CN 114372321A CN 202111523459 A CN202111523459 A CN 202111523459A CN 114372321 A CN114372321 A CN 114372321A
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temperature
rotor
angle
male rotor
shell
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徐明照
袁玮玮
李宁
王辰
张泉明
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Shanghai Qiyao Screw Machinery Co ltd
Shanghai Marine Diesel Engine Research Institute
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Shanghai Marine Diesel Engine Research Institute
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Abstract

The technical problem to be solved by the invention is to provide a temperature design method of a water interlayer shell of a double-screw compressor, which is characterized in that according to given process medium gas parameters, model parameters of the double-screw compressor and cooling water parameters, the temperature distribution of the inner wall of the water interlayer shell before cooling the water interlayer and a relation curve equation between the process medium gas temperature and the temperature drop of the inner wall of the water interlayer shell are calculated, and then the temperature distribution of the inner wall of the water interlayer shell before cooling the water interlayer is subtracted by the temperature drop of the inner wall of the water interlayer shell to obtain the temperature distribution of the inner wall of the water interlayer shell after cooling the water interlayer. By utilizing the design method, the temperature distribution of the inner wall of the shell of the double-screw compressor before and after the water interlayer is cooled can be quickly calculated according to the given cooling water parameters.

Description

Temperature design method for water interlayer shell of double-screw compressor
Technical Field
The invention relates to a screw compressor technology.
Background
The screw compressor belongs to a positive displacement compressor, and realizes gas compression along with the continuous reduction of the closed volume in the rotation process by forming the closed volume between a male rotor and a female rotor and a shell. In order to achieve high operation efficiency, it is necessary to control the leakage clearances in the gaps between the teeth of the male and female rotors, the tip clearance between the rotor and the casing, the clearance between the rotor and the exhaust end face of the casing, and the like, within a small range. However, under some working conditions, the intake and exhaust temperatures of the screw compressor generate huge differences, which causes large thermal deformation of the rotor and the casing, and thus the leakage gaps at various positions change irregularly, which causes the reduction of the operation reliability and the operation efficiency of the main engine, and meanwhile, the uncertainty of the gaps at various positions caused by the thermal deformation causes the difficulty in performance prediction during the design of the main engine, and increases the theoretical and actual design deviation.
The discharge temperature of a dry screw compressor depends mainly on the physical properties of the medium and the operating pressure ratio, which can generally be calculated by the following formula:
Figure BDA0003408628570000011
in the formula:
Tddischarge temperature of the compressor, K
TsSuction temperature of the compressor, K
εoExternal pressure ratio of compressor
m-multiple square process index
When the external pressure is high or the multi-aspect index of gas is high, the exhaust temperature of the screw compressor is high, and the inner wall surface of the shell is of a double-hole structure, the temperatures of the inner wall surface and the inner wall surface are different, so that the thermal expansion amount of the whole surface is uneven, the gap between the rotor and the inner wall surface of the shell is changed, the risk of the rotor rubbing the cylinder at the position with the smaller gap is increased, and the leakage loss at the position with the larger gap is increased, so that the efficiency of the main engine is reduced.
At present, in order to control the thermal deformation of the screw compressor, cooling media such as atomized cooling oil, atomized cooling water and the like are mostly sprayed at the inlet of the screw compressor, so that a good cooling effect is obtained. However, for some processes, the incorporation of any impurity gas is strictly prohibited and the above method is not feasible. For such working conditions, forced convection heat transfer is often used to achieve temperature control, such as a water jacket shell. Through increasing one deck casing in original cylinder outside, let in recirculated cooling water between the two-layer casing to reduce cylinder temperature. Because the volumes between the teeth of the screw compressor are spirally and axially pushed, the pressure and the temperature are continuously changed in the pushing process, so that the temperature distribution of the wall surface of the cylinder is more complex, and the cooling design of the water interlayer is also difficult.
For the calculation of the cooling effect of the water jacket, there are currently two main methods:
(1) in the experimental method, the temperature distribution condition of the shell of the testing machine is obtained by introducing cooling water with different flow rates to the testing machine under the specified working condition. The main disadvantage is that the test cost is very high, and the time for reaching the steady state balance of the temperature in the test is long, and the process needs to be repeated once every time the parameters are adjusted, so that the labor, material and time costs are considerable.
(2) And the CFD simulation method is used for simulating the internal flow field of the screw compressor through CFD software and then obtaining the temperature distribution of the shell of the screw compressor through hot fluid-solid coupling. The main defects are long time consumption, the gas in the screw compressor flows irregularly, a moving grid technology is needed to obtain a more accurate result, the quality requirement on the grid is high due to the tiny leakage gaps among the volumes among all the teeth, and the calculation result in the iteration process is easy to disperse. And the calculation process needs to be repeated once when the parameters are adjusted, so that the whole calculation period is very long, and the project implementation progress is seriously delayed.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a temperature design method of a water interlayer shell of a double-screw compressor, and by utilizing the design method, the temperature distribution of the inner wall of the shell of the double-screw compressor before and after the water interlayer is cooled can be quickly calculated according to given cooling water parameters.
The temperature design method of the water interlayer shell of the double-screw compressor comprises the following steps:
establishing a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the male rotor and the angle of the male rotor of the air inlet end surface of the male rotor and a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the female rotor and the angle of the female rotor of the air inlet end surface of the female rotor according to given process medium gas parameters and model parameters of the double-screw compressor;
obtaining a relational expression between the temperature of any point on the tooth profile of the male rotor section and the male rotor angle of the male rotor section according to the relational expression between the temperature of any point on the tooth profile of the male rotor air inlet end face and the male rotor angle of the male rotor air inlet end face, and obtaining a relational expression between the temperature of any point on the tooth profile of the female rotor section and the female rotor angle of the female rotor section according to the relational expression between the temperature of any point on the tooth profile of the female rotor air inlet end face and the female rotor angle of the female rotor air inlet end face;
obtaining the temperature distribution of the inner wall of the water interlayer shell before cooling the water interlayer according to a rotor angle corresponding to each point on the inner wall of the water interlayer shell on a longitudinal section of the shell perpendicular to the axis of the rotor, a relational expression between the temperature of any point on the tooth profile of the section of the male rotor and the angle of the male rotor on the section of the male rotor, and a relational expression between the temperature of any point on the tooth profile of the section of the female rotor and the angle of the female rotor on the section of the female rotor;
based on a cooling water convective heat transfer model, calculating the temperature drop of the inner wall of the water interlayer shell when the process medium gas is at different temperatures according to given cooling water parameters and process medium gas parameters to obtain a plurality of discrete point calculation results, and performing curve fitting on the plurality of discrete point calculation results to obtain a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell;
according to a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell, subtracting the temperature drop of the inner wall of the water interlayer shell from the temperature distribution of the inner wall of the water interlayer shell before the water interlayer is cooled to obtain the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled;
and comparing the highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled with a preset temperature threshold, and if the highest temperature value is lower than the temperature threshold, indicating that the given cooling water parameters are reasonable.
In the method for designing the temperature of the water interlayer shell of the double-screw compressor, if the highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled is greater than or equal to the temperature threshold value, the flow rate of the cooling water is changed, the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled at different flow rates is calculated, and a predicted relation curve between the highest temperature value of the inner wall of the water interlayer shell and the flow rate of the cooling water is obtained.
The invention has at least the following advantages and characteristics:
(1) according to the embodiment of the invention, the temperature distribution of the inner wall surface of the water interlayer shell of the double-screw compressor can be quickly calculated according to the given cooling water parameters, the process medium gas parameters and the model parameters of the double-screw compressor;
(2) the embodiment of the invention can provide a predicted change curve of the highest value of the temperature of the inner wall of the shell and the amount of cooling water, can greatly reduce the iteration times and provide guidance for adjusting the parameters of the cooling water, thereby quickly obtaining the target value;
(3) the temperature distribution result of the inner wall of the shell, which is obtained by calculation in the embodiment of the invention, can be used for temperature control design of the double-screw compressor, can also be used for research on thermal deformation of the screw compressor, and provides reference for clearance design and structural design of the screw compressor.
Drawings
Fig. 1 is a schematic flow chart showing a temperature design method of a water jacket shell of a twin-screw compressor according to an embodiment of the present invention.
Fig. 2 shows a schematic representation of the change in tooth space volume of a twin-screw compressor.
Fig. 3 shows a schematic diagram of a cooling water convection heat exchange model according to an embodiment of the present invention.
Detailed Description
The temperature design method of the water interlayer shell of the double-screw compressor comprises the following steps:
establishing a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the male rotor and the angle of the male rotor of the air inlet end surface of the male rotor and a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the female rotor and the angle of the female rotor of the air inlet end surface of the female rotor according to given process medium gas parameters and model parameters of the double-screw compressor;
obtaining a relational expression between the temperature of any point on the tooth profile of the male rotor section and the male rotor angle of the male rotor section according to the relational expression between the temperature of any point on the tooth profile of the male rotor air inlet end face and the male rotor angle of the male rotor air inlet end face, and obtaining a relational expression between the temperature of any point on the tooth profile of the female rotor section and the female rotor angle of the female rotor section according to the relational expression between the temperature of any point on the tooth profile of the female rotor air inlet end face and the female rotor angle of the female rotor air inlet end face;
obtaining the temperature distribution of the inner wall of the water interlayer shell before cooling the water interlayer according to a rotor angle corresponding to each point on the inner wall of the water interlayer shell on a longitudinal section of the shell perpendicular to the axis of the rotor, a relational expression between the temperature of any point on the tooth profile of the section of the male rotor and the angle of the male rotor on the section of the male rotor, and a relational expression between the temperature of any point on the tooth profile of the section of the female rotor and the angle of the female rotor on the section of the female rotor;
based on a cooling water convective heat transfer model, calculating the temperature drop of the inner wall of the water interlayer shell when the process medium gas is at different temperatures according to given cooling water parameters and process medium gas parameters to obtain a plurality of discrete point calculation results, and performing curve fitting on the plurality of discrete point calculation results to obtain a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell;
according to a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell, subtracting the temperature drop of the inner wall of the water interlayer shell from the temperature distribution of the inner wall of the water interlayer shell before the water interlayer is cooled to obtain the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled;
and comparing the highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled with a preset temperature threshold, and if the highest temperature value is lower than the temperature threshold, indicating that the given cooling water parameters are reasonable.
Further, if the highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled is larger than or equal to the temperature threshold, the flow rate of the cooling water is changed, the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled at different flow rates is calculated, and a predicted relation curve of the highest temperature value of the inner wall of the water interlayer shell and the flow rate of the cooling water is obtained.
The method for designing the temperature of the water jacket shell of the twin-screw compressor according to the present invention will be described in detail with reference to a specific embodiment. Referring to fig. 1, the method for designing the temperature of the water jacket shell of the twin-screw compressor of this embodiment includes the following steps:
a. given process media gas parameters and screw compressor model parameters were received as shown in table 1.
TABLE 1 Process Medium gas parameters and screw compressor model parameters
Figure BDA0003408628570000051
The process medium gas parameters also comprise medium physical parameters: specific heat at constant pressure CpSpecific heat at constant volume CvThe kinematic viscosity v, the prandtl number Pr and the Reynolds number Re.
b. Given cooling water parameters are received as shown in table 2.
TABLE 2 Cooling Water parameters
Figure BDA0003408628570000052
c. And establishing a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the male rotor and the angle of the male rotor of the air inlet end surface of the male rotor and a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the female rotor and the angle of the female rotor of the air inlet end surface of the female rotor according to given process medium gas parameters and model parameters of the double-screw compressor.
Temperature T (alpha) of any point on the tooth profile of the air inlet end surface of the male rotor1) Male rotor angle alpha with male rotor inlet end face1The relation of (A) is as follows:
Figure BDA0003408628570000061
temperature T (alpha) of any point on tooth form of air inlet end surface of female rotor2) Female rotor angle alpha with female rotor air inlet end face2The relation of (A) is as follows:
Figure BDA0003408628570000062
wherein: t issIs the suction temperature of the compressor; t isdIs the discharge temperature of the compressor; alpha is alpha1sIs the axial suction angle of the male rotor; alpha is alpha2sIs the axial suction angle of the female rotor;
Figure BDA0003408628570000063
is the torsion angle coefficient; tau is1zIs the male rotor twist angle; i is the gear ratio of the male rotor to the female rotor; k is an isentropic index, k is,
Figure BDA0003408628570000064
Cpis the constant pressure specific heat of the process medium gas, CvThe specific heat of the process medium gas with constant volume is used;
Figure BDA0003408628570000065
the angle of the male rotor at the end of the first stage of the compressor compression process;
Figure BDA0003408628570000066
is the internal compression corner of the male rotor.
The compression process of a twin-screw compressor is generally divided into two stages: the first stage is that the rotor tooth space volume is reduced until a contact line with unchanged shape and length is formed between a pair of tooth space volumes of the female rotor and the male rotor (only when the pressure of the screw compressor is relatively small, the compression process is terminated at the stage); the second phase ends from the first phase until the male rotor has rotated through a male rotor twist angle tau1zUntil then.
The change of the tooth space volume of the twin-screw compressor is shown in FIG. 2, when the female rotor teeth 1 'rotate to the tooth space area A immediately after the female rotor teeth 1' invade the male rotor teeth 101At the position, i.e. the start of compression, and also the start of the reduction of the tooth space volume, the tooth crest radial line O of the corresponding male rotor tooth 11W and O1O2The angle between the connecting lines is beta. O is1Is the axis of the male rotor, O2Is the axis of the female rotor. The angle of rotation of the male rotor at this position being specified to be zero, i.e. zero
Figure BDA0003408628570000067
(the male rotor angle referred to herein
Figure BDA0003408628570000068
I.e. the male rotor angle alpha of the inlet end face of the male rotor as described above1)。
Figure BDA0003408628570000071
Figure BDA0003408628570000072
Figure BDA0003408628570000073
In the formula:
r1-YangOuter radius of rotor
A-rotor center distance
r2-outer circle radius of female rotor
Figure BDA0003408628570000074
The angle of rotation of the male rotor at the end of the first stage
z1Male rotor tooth number
i-gear ratio
z2Number of female rotor teeth
Then in the first stage
Figure BDA0003408628570000075
Internal volume ratio epsilon of screw compressorvAngle of rotation with male rotor
Figure BDA0003408628570000076
The relationship between is
Figure BDA0003408628570000077
In the formula:
Figure BDA0003408628570000078
coefficient of torsion angle
τ1zMale rotor twist angle
In the second stage (
Figure BDA00034086285700000718
) Internal volume ratio εvAngle of rotation with male rotor
Figure BDA0003408628570000079
The relationship between is
Figure BDA00034086285700000710
Make the male rotor corner
Figure BDA00034086285700000711
Angle of rotation of female rotor
Figure BDA00034086285700000712
(female rotor angle as used herein)
Figure BDA00034086285700000713
I.e. the female rotor angle alpha of the inlet end face of the female rotor as described above2) The internal volume ratio epsilon can be obtained by the meshing relation of the male rotor and the female rotorvAngle of rotation with female rotor
Figure BDA00034086285700000714
The relationship between them.
In the first stage
Figure BDA00034086285700000715
Internal volume ratio epsilonvAngle of rotation with female rotor
Figure BDA00034086285700000716
The relationship between is
Figure BDA00034086285700000717
Second stage
Figure BDA0003408628570000081
Internal volume ratio epsilonvAngle of rotation with female rotor
Figure BDA0003408628570000082
The relationship between is
Figure BDA0003408628570000083
The temperature distribution of the inner wall surface of the shell before cooling is calculated, the temperature values are the same along the spiral line according to the spiral characteristics of the rotor, so that the three-dimensional problem can be converted into the two-dimensional problem, and the temperature distribution of the inner wall surface of the shell can be obtained according to the temperature distribution on the air inlet end surface.
d. Obtaining a relational expression between the temperature of any point on the tooth profile of the male rotor section and the male rotor angle of the male rotor section according to the relational expression between the temperature of any point on the tooth profile of the male rotor air inlet end face and the male rotor angle of the male rotor air inlet end face, and obtaining a relational expression between the temperature of any point on the tooth profile of the female rotor section and the female rotor angle of the female rotor section according to the relational expression between the temperature of any point on the tooth profile of the female rotor air inlet end face and the female rotor angle of the female rotor air inlet end face;
suppose that a point on the tooth profile of the male rotor section is F1，F1Point and male rotor axis O1Connecting line F between1O1And O1The angle between W (point W is shown in FIG. 2) is the male rotor angle β of the male rotor cross-section1Assuming that a point on the tooth profile of the female rotor section is F2，F2And the axis O of the female rotor2Connecting line F between2O2And O2The included angle between W is the angle beta of the female rotor2。
Temperature T (beta) of any point on tooth profile of male rotor section1) Male rotor angle beta with male rotor section1The relationship between them is:
Figure BDA0003408628570000084
temperature T (beta) of any point on tooth profile of cross section of female rotor2) Angle beta of the female rotor with respect to the cross-section of the female rotor2The relationship between them is:
Figure BDA0003408628570000091
in the formula: lambda [ alpha ]1Is the length-diameter ratio, lambda, of the male rotor2Is the aspect ratio of the female rotor; d1Is the diameter of the outer circle of the male rotor, d2The diameter of the outer circle of the female rotor; delta l is the axial distance between the cross section of the rotor and the air inlet end face of the rotor; t issIs the suction temperature of the compressor; t isdIs the discharge temperature of the compressor; alpha is alpha1sIs the axial suction angle of the male rotor; alpha is alpha2sIs the axial suction angle of the female rotor;
Figure BDA0003408628570000092
is the torsion angle coefficient; tau is1zIs the male rotor twist angle; i is the gear ratio of the male rotor to the female rotor; k is an isentropic index, k is,
Figure BDA0003408628570000093
Cpis the constant pressure specific heat of the process medium gas, CvThe specific heat of the process medium gas with constant volume is used;
Figure BDA0003408628570000094
the angle of the male rotor at the end of the first stage of the compressor compression process;
Figure BDA0003408628570000095
is the internal compression corner of the male rotor.
T (. beta.) described above1) And T (. beta.)2) Has taken the helical characteristics of the rotor into full account, by introducing the axial distance Δ l between the cross section of the rotor and the inlet end face of the rotor, and integrating it into the independent variable β1And beta2The temperature of any point on the three-dimensional tooth form of the rotor can be directly calculated without considering further conversion of the spiral characteristics of the rotor (namely, the point on the air inlet end surface is not required to be converted to the point on the three-dimensional tooth form along a spiral line equation), so that the calculation process is greatly simplified, and the calculation speed is improved.
e. And obtaining the temperature distribution of the inner wall of the water interlayer shell before cooling the water interlayer according to the rotor angle corresponding to each point on the inner wall of the water interlayer shell on the longitudinal section of the shell perpendicular to the axis of the rotor, the relational expression between the temperature of any point on the tooth profile of the section of the male rotor and the angle of the male rotor on the section of the male rotor, and the relational expression between the temperature of any point on the tooth profile of the section of the female rotor and the angle of the female rotor on the section of the female rotor.
During the rotation of the rotor, the temperature of any point on the inner wall of the housing is periodically changed, and the position of the rotor shown in fig. 2 is still exemplified as the position of 0 °, and if the point on the inner wall of the housing is on the male rotor side, the angle theta of the male rotor corresponding to the point on the longitudinal section of the housing perpendicular to the rotor axis can be obtained (assuming that the point is K)1，K1Point and male rotor axis O1Connecting line K between1O1And O1The angle between W is theta), and theta is substituted into the above-mentioned T (beta)1) Among the formulas (in this case beta)1Equal to theta), the temperature of the point can be obtained, and the period change interval of the temperature of the point is
Figure BDA0003408628570000101
Taking periodic variation interval
Figure BDA0003408628570000102
Substituting a plurality of discrete points in (b) into the above-mentioned T (β)1) In the formula, a periodic temperature change curve of the point on the inner wall of the shell can be further obtained; if a point on the inner wall of the housing is on the female rotor side, it can be obtained that the point corresponds to a female rotor angle θ (assuming that the point is K) on a longitudinal cross-section of the housing perpendicular to the rotor axis2，K2And point female rotor axis O2Connecting line K between2O2And O2The angle between W is theta), and theta is substituted into the above-mentioned T (beta)2) Among the formulas (in this case beta)2Equal to theta) is obtained, and the periodic variation interval of the point is
Figure BDA0003408628570000103
Taking periodic variation interval
Figure BDA0003408628570000104
Substituting a plurality of discrete points in (b) into the above-mentioned T (β)2) From the formula, the periodic temperature variation curve of the point on the inner wall of the shell can be further obtained.
f. Based on a cooling water convective heat transfer model, calculating the temperature drop of the inner wall of the water interlayer shell when the process medium gas is at different temperatures according to given cooling water parameters and process medium gas parameters to obtain a plurality of discrete point calculation results, and performing curve fitting on the plurality of discrete point calculation results to obtain a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell.
The process medium gas contacts with the inner wall surface of the shell to carry out convective heat transfer, and the cooling water contacts with the outer wall surface of the shell to carry out convective heat transfer. Due to the irregular structure of the screw compressor housing, the flow of the fluid in the compressor is also complicated, and it is difficult to calculate and obtain an analytic solution to the problem of heat transfer. The convective heat transfer model of the cooling water in this embodiment is shown in fig. 3, a shell infinitesimal with an angle d γ and an axial length l is taken, as shown by a shaded portion in fig. 3, because the angle is small, the infinitesimal can be approximated to a flat plate, and it is assumed that the temperature is kept constant when the fluid flows through the flat plate, the boundary layer effect is ignored, and the thermal radiation is not considered.
According to the principles related to heat transfer[3]The correlation formula of the fluid sweep-out full-plate long isothermal flat laminar flow heat exchange is as follows:
Figure BDA0003408628570000105
the correlation formula of the turbulent heat exchange of the fluid sweep full-plate long isothermal flat plate is as follows:
Figure BDA0003408628570000106
in the formula:
Nul-nussel number
The surface heat transfer coefficient h and the heat exchange amount phi of the flat plate are
Figure BDA0003408628570000107
φ＝h·S·Δt
In the formula:
λl-thermal conductivity
length of l-plate
S-fluid flow area
Delta t-temperature difference of heat exchange
When the steady state is reached, the temperature of the shell is kept unchanged, namely the heat exchange quantity phi of the medium gas and the inner wall surface of the cylindergEqual to the heat exchange amount phi between the outer wall surface of the cylinder and the cooling waterwAnd calculating to obtain a plurality of groups of calculation results of the gas temperature and the temperature drop (namely the delta t) of the inner wall of the water interlayer shell. And performing curve fitting on the plurality of groups of calculation results of the gas temperature and the shell temperature drop discrete point to obtain a relation curve equation between the gas temperature and the temperature drop of the inner wall of the water interlayer shell.
g. According to a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell, subtracting the temperature drop of the inner wall of the water interlayer shell from the temperature distribution of the inner wall of the water interlayer shell before the water interlayer is cooled to obtain the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled.
h. Comparing the highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled with a preset temperature threshold, and if the highest temperature value is lower than the temperature threshold, indicating that the given cooling water parameter is reasonable and meets the design requirement, wherein the current cooling water parameter is a target value; otherwise, judging that the given cooling water parameter is unqualified, changing the flow of the cooling water, calculating the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled when the flow of the cooling water is different, obtaining a prediction relation curve of the highest temperature value of the inner wall of the water interlayer shell and the flow of the cooling water, referring to the prediction relation curve, returning to the step b to adjust the cooling water parameter, and repeating the calculation process until the calculated highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled is lower than the temperature threshold.

Claims (7)

1. The temperature design method of the water interlayer shell of the double-screw compressor is characterized by comprising the following steps:
establishing a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the male rotor and the angle of the male rotor of the air inlet end surface of the male rotor and a relational expression between the temperature of any point on the tooth profile of the air inlet end surface of the female rotor and the angle of the female rotor of the air inlet end surface of the female rotor according to given process medium gas parameters and model parameters of the double-screw compressor;
obtaining a relational expression between the temperature of any point on the tooth profile of the male rotor section and the male rotor angle of the male rotor section according to the relational expression between the temperature of any point on the tooth profile of the male rotor air inlet end face and the male rotor angle of the male rotor air inlet end face, and obtaining a relational expression between the temperature of any point on the tooth profile of the female rotor section and the female rotor angle of the female rotor section according to the relational expression between the temperature of any point on the tooth profile of the female rotor air inlet end face and the female rotor angle of the female rotor air inlet end face;
obtaining the temperature distribution of the inner wall of the water interlayer shell before cooling the water interlayer according to a rotor angle corresponding to each point on the inner wall of the water interlayer shell on a longitudinal section of the shell perpendicular to the axis of the rotor, a relational expression between the temperature of any point on the tooth profile of the section of the male rotor and the angle of the male rotor on the section of the male rotor, and a relational expression between the temperature of any point on the tooth profile of the section of the female rotor and the angle of the female rotor on the section of the female rotor;
based on a cooling water convective heat transfer model, calculating the temperature drop of the inner wall of the water interlayer shell when the process medium gas is at different temperatures according to given cooling water parameters and process medium gas parameters to obtain a plurality of discrete point calculation results, and performing curve fitting on the plurality of discrete point calculation results to obtain a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell;
according to a relation curve equation between the temperature of the process medium gas and the temperature drop of the inner wall of the water interlayer shell, subtracting the temperature drop of the inner wall of the water interlayer shell from the temperature distribution of the inner wall of the water interlayer shell before the water interlayer is cooled to obtain the temperature distribution of the inner wall of the water interlayer shell after the water interlayer is cooled;
and comparing the highest temperature value of the inner wall of the water interlayer shell after the water interlayer is cooled with a preset temperature threshold, wherein if the highest temperature value is lower than the temperature threshold, the given cooling water parameter is reasonable.
2. The method for designing the temperature of the water jacket shell of the twin-screw compressor as recited in claim 1, wherein if the maximum temperature value of the inner wall of the water jacket shell after the cooling of the water jacket is greater than or equal to the temperature threshold value, the flow rate of the cooling water is changed, the temperature distribution of the inner wall of the water jacket shell after the cooling of the water jacket is calculated at different flow rates of the cooling water, and a predicted relationship curve between the maximum temperature value of the inner wall of the water jacket shell and the flow rate of the cooling water is obtained.
3. The method for designing temperature of water jacket shell of twin-screw compressor according to claim 1, wherein temperature T (β) of any point on the profile of the male rotor cross section1) Male rotor angle beta with male rotor section1The relationship between them is:
Figure FDA0003408628560000021
temperature T (beta) of any point on tooth profile of cross section of female rotor2) Angle beta of the female rotor with respect to the cross-section of the female rotor2The relationship between them is:
Figure FDA0003408628560000022
in the formula: lambda [ alpha ]1Is the length-diameter ratio, lambda, of the male rotor2Is the aspect ratio of the female rotor; d1Is the diameter of the outer circle of the male rotor, d2The diameter of the outer circle of the female rotor; delta l is the axial distance between the cross section of the rotor and the air inlet end face of the rotor; t issIs the suction temperature of the compressor; t isdIs the discharge temperature of the compressor; alpha is alpha1sIs the axial suction angle of the male rotor; alpha is alpha2sIs the axial suction angle of the female rotor;
Figure FDA0003408628560000023
is the torsion angle coefficient; tau is1zIs the male rotor twist angle; i is the gear ratio of the male rotor to the female rotor; k is an isentropic index, k is,
Figure FDA0003408628560000024
Cpis the constant pressure specific heat of the process medium gas, CvThe specific heat of the process medium gas with constant volume is used;
Figure FDA0003408628560000025
the angle of the male rotor at the end of the first stage of the compressor compression process;
Figure FDA0003408628560000026
is the internal compression corner of the male rotor.
4. The method for designing temperature of water jacket shell of twin-screw compressor according to claim 1 or 3, wherein temperature T (α) at any point on the profile of the inlet end face of the male rotor1) Male rotor angle alpha with male rotor inlet end face1The relation of (A) is as follows:
Figure FDA0003408628560000031
temperature T (alpha) of any point on tooth form of air inlet end surface of female rotor2) Female rotor angle alpha with female rotor air inlet end face2The relation of (A) is as follows:
Figure FDA0003408628560000032
wherein: t issIs the suction temperature of the compressor; t isdIs the discharge temperature of the compressor; alpha is alpha1sIs the axial suction angle of the male rotor; alpha is alpha2sIs the axial suction angle of the female rotor;
Figure FDA0003408628560000033
is the torsion angle coefficient; tau is1zIs the male rotor twist angle; i is the gear ratio of the male rotor to the female rotor; k is an isentropic index, k is,
Figure FDA0003408628560000034
Cpis the constant pressure specific heat of the process medium gas, CvThe specific heat of the process medium gas with constant volume is used;
Figure FDA0003408628560000035
the angle of the male rotor at the end of the first stage of the compressor compression process;
Figure FDA0003408628560000036
is the internal compression corner of the male rotor.
5. The method for designing the temperature of the water jacket shell of the twin-screw compressor according to claim 1, wherein the cooling water parameters include a cooling water temperature and a cooling water flow rate.
6. The method for designing the temperature of the water jacket shell of the twin-screw compressor according to claim 1, wherein the given process medium gas parameter comprises specific heat at constant pressure CpSpecific heat at constant volume CvThe system comprises a compressor, a kinematic viscosity upsilon, a Prandtl number Pr, a Reynolds number Re, a compressor inlet temperature, a compressor inlet pressure, a process medium gas mass flow and an industrial medium gas component.
7. The method for designing the temperature of the water jacket shell of the twin-screw compressor according to claim 1, wherein the model parameters of the twin-screw compressor comprise a model number, an aspect ratio of a male rotor, an aspect ratio of a female rotor and an internal volume ratio.
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