CN112361660A - Heat pump system and method for setting design flow thereof - Google Patents
Heat pump system and method for setting design flow thereof Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 15
- 230000006835 compression Effects 0.000 claims description 13
- 238000007906 compression Methods 0.000 claims description 13
- 239000013589 supplement Substances 0.000 claims description 9
- 238000005452 bending Methods 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 239000007789 gas Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
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- 239000002918 waste heat Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 208000006673 asthma Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
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- 238000005057 refrigeration Methods 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/06—Heat pumps characterised by the source of low potential heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/022—Compressor control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/07—Details of compressors or related parts
- F25B2400/077—Compressor control units, e.g. terminal boxes, mounted on the compressor casing wall containing for example starter, protection switches or connector contacts
Abstract
The invention relates to a heat pump system and a method for setting design flow thereof. The heat pump system comprises a low-pressure stage compressor, a high-pressure stage compressor, a condenser, a throttle valve and an evaporator which are sequentially connected in series; wherein the low pressure stage compressor comprises a first impeller and a second impeller connected in series; the high pressure stage compressor includes a third impeller; the low pressure stage compressor and the high pressure stage compressor are configured to operate alternatively, or simultaneously. The low-pressure stage compressor works independently under the low-temperature working condition or the medium-temperature working condition, the low-pressure stage compressor and the high-pressure stage compressor work in series and simultaneously under the high-temperature working condition, and can run efficiently under the low-temperature working condition and the high-temperature working condition or under the medium-temperature working condition and the high-temperature working condition, so that the comprehensive operation energy consumption of the heat pump system all the year is reduced.
Description
Technical Field
The invention relates to the field of air conditioning, in particular to a heat pump system and a method for setting design flow of the heat pump system.
Background
The water source heat pump technology can effectively recover low-temperature waste heat, the heat pump working medium is utilized to evaporate and absorb heat in the evaporator to recover the water source waste heat, the evaporated steam is compressed by the compressor to raise the temperature and the pressure, the energy grade of the evaporated steam is improved and the evaporated steam is condensed in the condenser, and the released heat can be used for regional heating and the like.
The water source heat pump mainly comprises three working conditions of low temperature, medium temperature and high temperature, the water source heat pump in the related technology can not well meet more than two heat pump working conditions, even if the water source heat pump simultaneously meets more than two working conditions, the operation range is narrow, and a certain working condition runs inefficiently, so that huge energy waste is caused.
Disclosure of Invention
Some embodiments of the present invention provide a heat pump system and a method for setting a design flow thereof, which are used to alleviate the problem that a heat pump system in the related art cannot better meet requirements of more than two working conditions.
Some embodiments of the present invention provide a heat pump system including a low-pressure stage compressor, a high-pressure stage compressor, a condenser, a throttle valve, and an evaporator connected in series in this order;
wherein the low pressure stage compressor comprises a first impeller and a second impeller connected in series; the high pressure stage compressor includes a third impeller; the low pressure stage compressor and the high pressure stage compressor are configured to operate alternatively, or simultaneously.
In some embodiments, the heat pump system further comprises an economizer, the throttle comprising a first throttle and a second throttle connected in series, the economizer disposed between the first throttle and the second throttle.
In some embodiments, the heat pump system further comprises an air supplement pipeline, an input end of the air supplement pipeline is connected with the economizer, an output end of the air supplement pipeline is divided into a first branch and a second branch, the first branch is connected to the low-pressure stage compressor, and the second branch is connected between the low-pressure stage compressor and the high-pressure stage compressor; the first branch and the second branch are each configured to be selectively connected or disconnected.
In some embodiments of the present invention, the,
the first branch is configured to be connected when the low pressure stage compressor is operated alone, and the second branch is configured to be disconnected when the low pressure stage compressor is operated alone;
the first branch circuit is configured to be disconnected when the low pressure stage compressor and the high pressure stage compressor are simultaneously operated, and the second branch circuit is configured to be connected when the low pressure stage compressor and the high pressure stage compressor are simultaneously operated.
In some embodiments, the low pressure stage compressor is configured to operate at low or medium temperature conditions and the high pressure stage compressor is configured to not operate at low or medium temperature conditions; the low pressure stage compressor and the high pressure stage compressor are configured to operate simultaneously at high temperature conditions.
In some embodiments, the second impeller is located downstream of the first impeller, the blades used in the first impeller include long blades and short blades, the long blades and the short blades are alternately arranged around the central axis of the first impeller, and the blades used in the second impeller and the third impeller are all blades of equal length.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
d1/D2＝0.029～0.035；
wherein d is1Is the diameter of the impeller inlet hub, D2Is the outer diameter of the impeller.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
D0/d1＝2～2.5；
wherein D is0Is the diameter of the impeller inlet, d1Is the impeller inlet hub diameter.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
the rear bend angle beta is 47-52 degrees;
and the backward bending angle beta is an included angle between a tangent of the outlet end of the blade and a tangent of the edge of the impeller corresponding to the outlet end of the blade.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
D0/D2＝0.055～0.062；
wherein D is0Is the diameter of the impeller inlet, D2Is the outer diameter of the impeller.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
d2/D2＝0.055～0.065；
wherein d is2Is the width of the impeller outlet, D2Is the outer diameter of the impeller.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
d3/d2＝0.72～0.76；
wherein d is3Is the diffuser width, d2Is the impeller exit width.
In some embodiments, the first impeller, the second impeller, and the third impeller each satisfy the following relationship:
D3/D2＝1.13～1.16；
wherein D is3The diameter of the wheel cover side is the diameter after convergence; d2Is the outer diameter of the impeller.
Some embodiments of the present invention provide a method for setting a design flow rate of the heat pump system, which includes:
obtaining the design flow q when the medium temperature working condition or the low temperature working condition operates efficientlym1Run time weight ofK1；
Obtaining the design flow q when the high-temperature working condition operates efficientlym2Run time weight of K2；
Wherein q ism1＜qm2，K1+K2＝1；
Presetting the design flow of a heat pump system as qm，qm＝qm1+(qm2-qm1)*K2And designing the profile of the impeller and estimating the performance, wherein if the compression pressure ratio of the high-pressure stage compressor and the low-pressure stage compressor during simultaneous working and the relative Mach number of the inlet of each impeller meet the requirements, the design flow Q of the heat pump system is Qm。
In some embodiments, if the compression pressure ratio of the high-pressure stage compressor and the low-pressure stage compressor working simultaneously and the relative mach number of the inlet of each impeller do not meet the requirement, the design flow q of the heat pump system is presetmOn the basis of (A) and (q)m*(K1/(K2*(K1+K2)))；
And designing the molded line of the impeller again and estimating the performance until the compression pressure ratio when the high-pressure stage compressor and the low-pressure stage compressor work simultaneously and the relative Mach number of the inlet of each impeller meet the requirements, and at the moment, the design flow Q of the heat pump system is Qm+N*A；
Wherein N is an integer greater than 0 and represents the number of times A is increased.
Based on the technical scheme, the invention at least has the following beneficial effects:
in some embodiments, the low pressure stage compressor comprises a first impeller and a second impeller connected in series; the high pressure stage compressor includes a third impeller; the low pressure stage compressor and the high pressure stage compressor are configured to operate alternatively or simultaneously; the low-pressure stage compressor works independently under the low-temperature working condition or the medium-temperature working condition, the low-pressure stage compressor and the high-pressure stage compressor work in series and simultaneously under the high-temperature working condition, and can run efficiently under the low-temperature working condition and the high-temperature working condition or under the medium-temperature working condition and the high-temperature working condition, so that the comprehensive operation energy consumption of the heat pump system all the year is reduced.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a schematic diagram of a heat pump system provided in accordance with some embodiments of the present invention;
FIG. 2 is a schematic diagram of a first operating condition of a heat pump system provided in accordance with some embodiments of the present invention;
FIG. 3 is a schematic diagram of a second operating condition of the heat pump system provided in accordance with some embodiments of the present invention;
FIG. 4 is a schematic view of a first impeller of a heat pump system provided in accordance with some embodiments of the present invention;
FIG. 5 is a schematic view of a second impeller of a heat pump system provided in accordance with some embodiments of the present invention;
FIG. 6 is an enlarged, fragmentary view of the second impeller shown in FIG. 5;
fig. 7 is a schematic cross-sectional view of the second impeller shown in fig. 5.
The reference numbers in the drawings illustrate the following:
1-a low pressure stage compressor; 11-a first impeller; 111-long leaf; 112-short leaf; 12-a second impeller;
2-a high pressure stage compressor; 21-a third impeller;
3-a condenser;
41-a first throttle valve; 42-a second throttle valve;
5-an evaporator;
6-an economizer;
7-a gas supply pipeline; 71-first branch; 72-second branch.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the present invention.
The low-temperature heat pump can provide hot water at 46 ℃ so as to meet the building project of cold and heat supply by adopting a central air conditioner; the medium-temperature centrifugal heat pump can provide hot water at 46-55 ℃ to meet the heat supply requirement of heating of residential projects; the high-temperature centrifugal heat pump can provide hot water at 55-85 ℃ to realize the transformation of heat supply boiler equipment, the hot water supply of an energy station and the like.
The centrifugal water source heat pump has the advantages Of large single-machine refrigeration heating capacity, environmental protection, no pollution, high COP (Coefficient Of Performance). However, since the pressure ratio of the working condition of the heat pump is high, if more than two working conditions of the heat pump are met, the operation range is narrow, and a certain working condition operates inefficiently, so that huge energy waste is caused, so that the centrifugal heat pump in the related art can only meet one of three working conditions, namely a low-temperature working condition, a medium-temperature working condition and a high-temperature working condition, basically.
However, the requirement of a client on the temperature of the hot water side is changed, the hot water side can cover two working condition ranges of a medium temperature and a high temperature, the operation time of the two working conditions is different, the pressure ratio of a common medium temperature heat pump (the ratio of the total outlet pressure to the total inlet pressure of the compressor) is 2.5-4, the pressure ratio of the high temperature heat pump is generally higher than 4.0, 4.0 is the limit pressure ratio of a single-stage centrifugal compressor, the Mach number of the blade tip of the impeller inlet exceeds 1 at the moment, transonic flow is achieved, shock wave loss is easy to generate, and the efficiency is low; if multi-stage compression is adopted, the medium-temperature working condition and the high-temperature working condition respectively reach the highest efficiency, the difference of the pneumatic structure parameters is large, the working condition pressure ratio of the high-temperature heat pump is high, the working condition pressure ratio of the high-temperature heat pump is close to an asthmatic and earthquake area, the working condition pressure ratio of the medium-temperature heat pump is relatively small, the working condition pressure ratio of the medium-temperature heat pump.
Based on this, some embodiments of the present disclosure provide a heat pump system that is capable of operating efficiently at least at medium and high temperature heat pump operating conditions.
In some embodiments, as shown in fig. 1, the heat pump system comprises a low pressure stage compressor 1, a high pressure stage compressor 2, a condenser 3, a throttle valve, and an evaporator 5 connected in series in that order.
Wherein the low pressure stage compressor 1 comprises a first impeller 11 and a second impeller 12 connected in series; the high-pressure stage compressor 2 comprises a third impeller 21; the low-pressure stage compressor 1 and the high-pressure stage compressor 2 are configured to operate alternatively, or simultaneously.
In some embodiments, the low pressure stage compressor 1 comprises at least two impellers, the high pressure stage compressor 2 comprises at least one impeller, and the low pressure stage compressor 1 comprises more impellers than the high pressure stage compressor.
In some embodiments, the low pressure stage compressor 1 is a two stage compressor with two impellers. The high-pressure stage compressor 2 is a single-stage compressor having one impeller.
In some embodiments, low pressure stage compressor 1 is configured to operate at low or medium temperature conditions, and high pressure stage compressor 2 is configured to not operate at low or medium temperature conditions; the low-pressure stage compressor 1 and the high-pressure stage compressor 2 are configured to simultaneously operate at a high-temperature operating condition.
The low-pressure stage compressor 1 works independently under the low-temperature working condition or the medium-temperature working condition, and the low-pressure stage compressor 1 and the high-pressure stage compressor 2 work in series and simultaneously under the high-temperature working condition, so that the heat pump system can run efficiently under the low-temperature working condition and the high-temperature working condition or under the medium-temperature working condition and the high-temperature working condition, and the comprehensive running energy consumption of the heat pump system all the year around is reduced.
In some embodiments, the compressor in the heat pump system includes a low-pressure stage compressor 1 and a high-pressure stage compressor 2, the low-pressure stage compressor 1 adopts two-stage compression, the high-pressure stage compressor 2 adopts single-stage compression, the low-pressure stage is a two-stage air supply structure, the low-pressure stage compressor 1 and the high-pressure stage compressor 2 are connected in series to meet the working condition of the high-temperature heat pump, and the low-pressure stage compressor 1 operates alone to meet the working condition of the medium-temperature heat pump or the working condition of.
The low-temperature working condition in the disclosure is a working condition for providing hot water with the temperature of 46 ℃ or lower, the medium-temperature working condition is a working condition for providing hot water with the temperature of more than 46 ℃ and less than 55 ℃, and the high-temperature working condition is a working condition for providing hot water with the temperature of more than 55 ℃ and less than or equal to 85 ℃.
In some embodiments, the heat pump system further comprises an economizer 6 comprising a first throttle 41 and a second throttle 42 connected in series, the economizer 6 being provided between the first throttle 41 and the second throttle 42.
In some embodiments, the heat pump system further includes an air supplement pipeline 7, an input end of the air supplement pipeline 7 is connected with the economizer 6, an output end of the air supplement pipeline 7 is divided into a first branch 71 and a second branch 72, the first branch 71 is connected to the low-pressure stage compressor 1, and the second branch 72 is connected between the low-pressure stage compressor 1 and the high-pressure stage compressor 2; the first branch 71 and the second branch 72 are each configured to be selectively connected or disconnected.
In some embodiments, the first branch 71 is connected between the first impeller 11 and the second impeller 12 of the low-pressure stage compressor 1.
In some embodiments, the first branch 71 is configured to be connected when the low pressure stage compressor 1 is operated alone, and the second branch 72 is configured to be disconnected when the low pressure stage compressor 1 is operated alone.
The first branch 71 is configured to be disconnected when the low pressure stage compressor 1 and the high pressure stage compressor 2 are simultaneously operated, and the second branch 72 is configured to be connected when the low pressure stage compressor 1 and the high pressure stage compressor 2 are simultaneously operated.
As shown in fig. 2, in the high-temperature operating condition, the low-pressure stage compressor 1 and the high-pressure stage compressor 2 operate simultaneously, the first branch 71 is disconnected, the second branch 72 is connected, that is, the input end of the gas supply line 7 is connected to the economizer 6, and the output end of the gas supply line 7 is connected between the low-pressure stage compressor 1 and the high-pressure stage compressor 2.
As shown in fig. 3, in the low-temperature or medium-temperature operating condition, the low-pressure stage compressor 1 operates, the high-pressure stage compressor 2 does not operate, the high-pressure stage compressor 2 corresponds to a passage, the first branch 71 is connected, the second branch 72 is disconnected, that is, the input end of the air supply line 7 is connected to the economizer 6, and the output end of the air supply line 7 is connected between the first impeller 11 and the second impeller 12 of the low-pressure stage compressor 1.
Of course, under low-temperature or medium-temperature conditions, the high-pressure stage compressor 2 may be selected to operate, the low-pressure stage compressor 1 does not operate, the low-pressure stage compressor 1 is equivalent to a passage, and one of the first branch 71 and the second branch 72 is communicated, that is, the input end of the gas supply pipeline 7 is connected to the economizer 6, and the output end of the gas supply pipeline 7 is connected to the high-pressure stage compressor 2.
In some embodiments, as shown in fig. 1, the second impeller 12 is located downstream of the first impeller 11, as shown in fig. 4, the first impeller 11 employs blades including long blades 111 and short blades 112, the long blades 111 and the short blades 112 are alternately arranged around the central axis of the first impeller 11, as shown in fig. 5, and the second impeller 12 and the third impeller 21 each employ blades of equal length.
For the low-pressure stage compressor 1, the inlet specific volume of the first impeller, namely the first impeller 11, is larger, the relative mach number of the inlet is larger, long and short blades are preferably arranged, and the second impeller, namely the second impeller 12, is arranged by full-length blades; in addition, the third impeller 21 also employs a full-length blade arrangement.
The "length" and "length" of the blade herein refer to the dimension of the blade in the direction extending from the impeller hub to the impeller outer edge.
In some embodiments, as shown in fig. 7, to ensure the reliability of the operation at the high pressure ratio and to increase the blade root stress, the first impeller 11, the second impeller 12, and the third impeller 21 all satisfy the following relationship:
d1/D2＝0.029～0.035；
wherein d is1Is the diameter of the impeller inlet hub, D2Is the outer diameter of the impeller.
In some embodiments, as shown in fig. 7, to obtain a better airflow mach number, the first impeller 11, the second impeller 12, and the third impeller 21 all satisfy the following relationship:
D0/d1＝2～2.5；
wherein D is0Is the diameter of the impeller inlet, d1Is the impeller inlet hub diameter.
In some embodiments, as shown in fig. 7, the first impeller 11, the second impeller 12, and the third impeller 21 each satisfy the following relationship:
the rear bend angle beta is 47-52 degrees to adapt to the operating condition of the high-pressure head;
as shown in fig. 6, the backward bending angle β is an included angle between a tangent line of the outlet end of the blade and a tangent line of the edge of the impeller corresponding to the outlet end of the blade.
In some embodiments, as shown in fig. 7, in order to prevent the curvature of the shroud from being too large, which causes the airflow separation to be deteriorated, and affects the uniformity of the impeller outlet speed, the first impeller 11, the second impeller 12, and the third impeller 21 all satisfy the following relationship:
D0/D2＝0.055～0.062；
wherein D is0Is the diameter of the impeller inlet, D2Is the outer diameter of the impeller.
In some embodiments, as shown in fig. 7, the first impeller 11, the second impeller 12, and the third impeller 21 each satisfy the following relationship:
d2/D2＝0.055～0.065；
wherein d is2Is the width of the impeller outlet, D2Is the outer diameter of the impeller.
In some embodiments, as shown in fig. 7, the impeller is optimized mainly by the diffuser width ratio in the operation range for the purpose of obtaining high efficiency, and the width ratio is too large to effectively alleviate the flow stall problem, and the effect of expanding the operation range is limited; the width ratio is too small, the diffuser speed reduction and pressure increase effect is not obvious, and the diffuser capacity is insufficient, so that the first impeller 11, the second impeller 12 and the third impeller 21 all satisfy the following relations:
d3/d2＝0.72～0.76；
wherein d is3Is the diffuser width, d2Is the impeller exit width.
In some embodiments, as shown in fig. 7, considering that the impeller outlet shroud inclination angle is greater than the hub, the first impeller 11, the second impeller 12 and the third impeller 21 all satisfy the following relationship:
D3/D2＝1.13～1.16；
wherein D is3The diameter of the wheel cover side is the diameter after convergence; d2Is the outer diameter of the impeller.
To sum up, D0Is the impeller inlet diameter. D1Impeller blade inlet diameter. D2Is the outer diameter of the impeller. D3The diameter of the diffuser is the diameter after the wheel cover side converges, namely the wheel cover side is provided with an inclined surface, the width of a flow passage of the diffuser is gradually narrowed from the initial point to the final point of the inclined surface, and the diameter at the final point of the inclined surface is D3。
d1Is the diameter of the impeller inlet hub; d2Is the impeller exit width; d3Is the diffuser width (the width of the flow passage in the diffuser).
In some embodiments, the hub side is not convergent, the straight side is aligned with the impeller exit side, and a fillet transition is made to accommodate the shroud and hub exit flow.
Some embodiments provide a method for setting a design flow rate of the heat pump system, which includes:
obtaining the design flow q when the medium temperature working condition or the low temperature working condition operates efficientlym1Run time weight of K1；
Obtaining the design flow q when the high-temperature working condition operates efficientlym2Run time weight of K2；
Wherein q ism1＜qm2，K1+K2＝1；
Presetting the design flow of a heat pump system as qm，qm＝qm1+(qm2-qm1)*K2The impeller profile design and performance pre-estimation are carried out, if the high-pressure stage compressor 2 and the low-pressure stage compressor 1 work simultaneously, the compression is carried outThe pressure ratio and the relative Mach number of the inlet of each impeller meet the requirements, and then the design flow Q of the heat pump system is Qm。
In some embodiments, if the compression pressure ratio and the impeller inlet mach number of the high-pressure stage compressor 2 and the low-pressure stage compressor 1 working simultaneously do not meet the requirement, the design flow q of the heat pump system is presetmOn the basis of (A) and (q)m*(K1/K2*(K1+K2)；
Designing the impeller profile again and estimating the performance until the compression pressure ratio and the impeller inlet Mach number of the high-pressure stage compressor 2 and the low-pressure stage compressor 1 working simultaneously meet the requirements, and at the moment, the design flow Q of the heat pump system is Qm+N*A；
Wherein N is an integer greater than 0 and represents the number of times A is increased.
The design flow rate of the medium-temperature working condition and the high-temperature working condition is different, the operation time is different, the design flow rate is related to the annual comprehensive energy efficiency of the unit under the two working conditions, if the design flow rate of the medium-temperature working condition is taken as the standard, the performance of the high-temperature working condition is greatly reduced, and if the design flow rate of the high-temperature working condition is taken as the standard, the performance of the medium-temperature working condition is also greatly reduced; based on this, according to the setting method of the design flow of the heat pump system provided by the embodiment of the disclosure, the low-pressure stage compressor 1 and the high-pressure stage compressor 2 are connected in series, and the operation time weights of the medium-temperature working condition and the high-temperature working condition are comprehensively considered, so that the unit has better comprehensive performance under the medium-temperature heat pump working condition and the high-temperature heat pump working condition.
Similarly, the design flow of the low-temperature working condition and the high-temperature working condition is different, the operation time is different, the design flow is related to the annual comprehensive energy efficiency of the unit under the two working conditions, if the design flow of the low-temperature working condition is taken as the standard, the performance of the high-temperature working condition is greatly reduced, and if the design flow of the high-temperature working condition is taken as the standard, the performance of the low-temperature working condition is also greatly reduced; based on this, according to the setting method of the design flow of the heat pump system provided by the embodiment of the disclosure, the low-pressure stage compressor 1 and the high-pressure stage compressor 2 are connected in series, and the operation time weights of the low-temperature working condition and the high-temperature working condition are comprehensively considered, so that the unit has better comprehensive performance under the two working conditions of the low-temperature heat pump working condition and the high-temperature heat pump working condition.
Wherein the design flow q when the medium temperature working condition or the low temperature working condition operates efficientlym1The method can be set according to the requirements of customers, such as: q. q.sm1The flow rate of the heat pump system expected by a customer when the heat pump system operates efficiently under the medium-temperature working condition or the low-temperature working condition. Run time weight K1The method can be set according to the requirements of customers, such as: k1The time that the customer wants the heat pump system to operate in the medium-temperature working condition or the low-temperature working condition is the proportion of the total time in one day or one month.
Similarly, the design flow q when the high-temperature working condition operates efficientlym2The method can be set according to the requirements of customers, such as: q. q.sm2The flow rate of the heat pump system expected by a customer when the heat pump system operates efficiently under a high-temperature working condition. Run time weight K2The method can be set according to the requirements of customers, such as: k2The time that the customer wants the heat pump system to operate at a high temperature condition is a proportion of the total time for a day or a month.
Wherein q ism1＜qm2，K1+K2＝1。
In some embodiments, after the design flow of the heat pump system is set, the profile of the impeller is designed and the performance is pre-estimated, so that the compression pressure ratio of the high-pressure stage compressor 2 and the low-pressure stage compressor 1 working simultaneously meets the requirement (including the requirement of meeting the high-temperature working condition), and the relative mach number of the inlet of each impeller meets the requirement, for example: the relative inlet Mach number of the impeller of the last stage is less than 0.8. Generally, the inlet mach number of the last stage of impeller is the largest, the inlet mach number of the last stage of impeller is less than 0.8, and the inlet mach number of each front stage of impeller is generally less than 0.8.
After the setting of the design flow rate of the heat pump system is completed, the following relationship is referred to for the profile design of each impeller (including the first impeller 11, the second impeller 12, and the third impeller 21):
d1/D2＝0.029～0.035；
D0/d1＝2～2.5；
the rear bend angle beta is 47-52 degrees;
D0/D2＝0.055～0.062；
d2/D2＝0.055～0.065；
d3/d2＝0.72～0.76；
D3/D2＝1.13～1.16；
wherein D is0Is the impeller inlet diameter. D2Is the outer diameter of the impeller. D3Is the shroud-side convergent rear diameter. d1Is the impeller inlet hub diameter. d2Is the impeller exit width; d3Is the diffuser width.
In the description of the present invention, it should be understood that the terms "first", "second", "third", etc. are used to define the components, and are used only for the convenience of distinguishing the components, and if not otherwise stated, the terms have no special meaning, and thus, should not be construed as limiting the scope of the present invention.
Furthermore, the technical features of one embodiment may be combined with one or more other embodiments advantageously without explicit negatives.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.
Claims (15)
1. A heat pump system is characterized by comprising a low-pressure stage compressor (1), a high-pressure stage compressor (2), a condenser (3), a throttle valve and an evaporator (5) which are sequentially connected in series;
wherein the low-pressure stage compressor (1) comprises a first impeller (11) and a second impeller (12) connected in series; the high-pressure stage compressor (2) comprises a third impeller (21); the low-pressure stage compressor (1) and the high-pressure stage compressor (2) are configured to operate alternatively or simultaneously.
2. The heat pump system according to claim 1, further comprising an economizer (6), said throttle valve comprising a first throttle valve (41) and a second throttle valve (42) connected in series, said economizer (6) being disposed between said first throttle valve (41) and said second throttle valve (42).
3. The heat pump system according to claim 2, further comprising an air-supplement line (7), an input of said air-supplement line (7) being connected to said economizer (6), an output of said air-supplement line (7) being divided into a first branch (71) and a second branch (72), said first branch (71) being connected to said low-pressure stage compressor (1), said second branch (72) being connected between said low-pressure stage compressor (1) and said high-pressure stage compressor (2); the first branch (71) and the second branch (72) are each configured to be selectively connected or disconnected.
4. The heat pump system of claim 3,
the first branch (71) is configured to be connected when the low pressure stage compressor (1) is operated alone, and the second branch (72) is configured to be disconnected when the low pressure stage compressor (1) is operated alone;
the first branch (71) is configured to be disconnected when the low-pressure stage compressor (1) and the high-pressure stage compressor (2) are simultaneously operated, and the second branch (72) is configured to be connected when the low-pressure stage compressor (1) and the high-pressure stage compressor (2) are simultaneously operated.
5. The heat pump system according to claim 1, wherein the low-pressure stage compressor (1) is configured to operate at a low-temperature condition or a medium-temperature condition, and the high-pressure stage compressor (2) is configured to not operate at the low-temperature condition or the medium-temperature condition; the low-pressure stage compressor (1) and the high-pressure stage compressor (2) are configured to operate simultaneously at high temperature conditions.
6. The heat pump system according to claim 1, wherein the second impeller (12) is located downstream of the first impeller (11), the first impeller (11) employing blades comprising long blades (111) and short blades (112), the long blades (111) and the short blades (112) being arranged alternately around the central axis of the first impeller (11), the second impeller (12) and the third impeller (21) employing blades each having an equal length.
7. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
d1/D2＝0.029～0.035；
wherein d is1Is the diameter of the impeller inlet hub, D2Is the outer diameter of the impeller.
8. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
D0/d1＝2～2.5；
wherein D is0Is the diameter of the impeller inlet, d1Is the impeller inlet hub diameter.
9. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
the rear bend angle beta is 47-52 degrees;
and the backward bending angle beta is an included angle between a tangent of the outlet end of the blade and a tangent of the edge of the impeller corresponding to the outlet end of the blade.
10. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
D0/D2＝0.055～0.062；
wherein D is0Is the diameter of the impeller inlet, D2Is the outer diameter of the impeller.
11. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
d2/D2＝0.055～0.065；
wherein d is2Is the width of the impeller outlet, D2Is the outer diameter of the impeller.
12. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
d3/d2＝0.72～0.76；
wherein d is3Is the diffuser width, d2Is the impeller exit width.
13. Heat pump system according to claim 1, characterized in that the first impeller (11), the second impeller (12) and the third impeller (21) all satisfy the following relationship:
D3/D2＝1.13～1.16；
wherein D is3The diameter of the wheel cover side is the diameter after convergence; d2Is the outer diameter of the impeller.
14. A method for setting a design flow rate of the heat pump system according to any one of claims 1 to 13, comprising:
obtaining the design flow q when the medium temperature working condition or the low temperature working condition operates efficientlym1Run time weight of K1；
Obtaining the design flow q when the high-temperature working condition operates efficientlym2Transporting and transportingLine time weight of K2；
Wherein q ism1＜qm2，K1+K2＝1；
Presetting the design flow of a heat pump system as qm，qm＝qm1+(qm2-qm1)*K2And designing impeller profile and estimating performance, wherein if the compression pressure ratio when the high-pressure stage compressor (2) and the low-pressure stage compressor (1) work simultaneously and the relative Mach number of the inlet of each impeller meet the requirements, the design flow Q of the heat pump system is Qm。
15. The setting method of the design flow rate of the heat pump system according to claim 14,
if one of the compression pressure ratio and the relative Mach number of the inlet of each impeller of the high-pressure stage compressor (2) and the low-pressure stage compressor (1) which work simultaneously does not meet the requirement, the design flow q of the heat pump system is presetmOn the basis of (A) and (q)m*(K1/(K2*(K1+K2)))；
And designing the impeller profile again and estimating the performance until the compression pressure ratio when the high-pressure stage compressor (2) and the low-pressure stage compressor (1) work simultaneously and the relative Mach number of the inlet of each impeller meet the requirements, and at the moment, the design flow Q of the heat pump system is Qm+N*A；
Wherein N is an integer greater than 0 and represents the number of times A is increased.
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