Energy-saving pump set based on pipeline characteristics of air conditioner variable water volume system and design method of energy-saving pump set

Abstract

The invention relates to air conditioner design, and provides an energy-saving pump set based on air conditioner variable water volume system pipeline characteristics and a design method of the energy-saving pump set. During design, the full flow ranges in summer and winter are obtained according to the annual hourly load of the system; drawing a system resistance-flow curve graph in a full flow range; the full flow range is divided into a plurality of flow sections, and a system resistance-flow curve is divided into a plurality of curve sections; selecting a water pump combination meeting each curve section according to a water pump conveying efficiency curve; the water pump combination is comprehensively selected according to the principle that the water pump conveying efficiency is high and the total number is small, or the water pump combination is selected according to the principle that the water pump total energy consumption is minimum; and the water pump combinations are connected in parallel to obtain the energy-saving pump set. The full-flow range of the system is divided into a plurality of sections to form water pump combinations with different flow gradients, so that the frequency conversion range of the water pump is reduced, the water pump always operates in a high-efficiency range, the utilization rate of a standby water pump in a traditional design is improved, and electric energy loss is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning design, and in particular to an energy-saving pump group based on pipeline characteristics of an air conditioning variable water volume system and a design method thereof. Background Art

[0002] In the traditional air-conditioning pump group water pump design method, the summer water pump (another spare pump is connected in parallel) and the winter water pump (another spare pump is connected in parallel) are usually selected according to the designed air-conditioning water pipe system and the flow required in summer and winter; the summer water pump is operated in summer, and when the summer air-conditioning load changes, the different load requirements are met by adding or subtracting the number of water pumps and the water pump frequency conversion; the winter water pump is operated in winter, and when the winter air-conditioning load changes, the different load requirements are also met by adding or subtracting the number of water pumps and the water pump frequency conversion; the standby water pump is only operated when the commonly used water pump fails.

[0003] Figure 1 This is a bar chart of the summer cooling load range and the number of times the air conditioning water system in a certain project appears. The calculated load of the project is 6383kw. It can be seen from the figure that the number of times 6383kw appears in the summer cooling load range is very small, and most of it is concentrated in partial load. Therefore, the flow of the air conditioning water system is also in the state of partial flow most of the time, and the corresponding water pump is also operating at partial flow most of the time. The water pump efficiency is the highest at its rated flow and head. When the water demand decreases, the water pump frequency is changed, and the delivery efficiency also decreases accordingly. Figure 2 This is a pump delivery efficiency curve. When the pump delivery flow is 500m 3 / h, head is 24mH2O, the pump delivery efficiency is the highest, reaching 83%; when the pump frequency conversion (n = 0.7n0, n0 is the rated speed) after the delivery flow is 200m 3 / h, and the head is 13.5mH2o, the pump delivery efficiency drops to 50%. That is, since the pump is running at partial flow most of the time, the pump efficiency is also not high, and the summer pump and the winter pump are not used together, and the standby pump is not well used. This will not only waste the pump's delivery capacity, but also waste a lot of electricity, increase investment, and is not conducive to energy conservation and environmental protection. Summary of the invention

[0004] The object of the present invention is to provide an energy-saving pump unit and a design method thereof based on the pipeline characteristics of an air-conditioning variable water volume system, so that the water pump always operates at a higher delivery efficiency.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides an energy-saving pump group design method based on the pipeline characteristics of an air-conditioning variable water volume system, comprising the following steps:

[0007] Step 1, according to the hourly load of the air-conditioning water pipe system throughout the year, the hourly flow of the air-conditioning water pipe system throughout the year is obtained, and the full flow range of the air-conditioning water pipe system is obtained according to the maximum and minimum flow rates;

[0008] Step 2, according to the most unfavorable end of the air-conditioning water pipe system, calculate the air-conditioning water pipe system resistance at different flow rates within the full flow range (including summer and winter), and draw a system resistance-flow curve;

[0009] Step 3, dividing the full flow range into N flow segments, dividing the system resistance-flow curve obtained in step 2 into N curve segments according to the obtained N flow segments, and obtaining multiple segmentation schemes; 3≤N≤5;

[0010] Step 4: for each segmentation scheme, according to the delivery efficiency curves of different water pumps, select the water pump type and water pump combination that meet the flow rate and resistance requirements of each curve segment in the corresponding segmentation scheme;

[0011] Step 5, select the preferred scheme from multiple segmentation schemes: except for the water pump combination corresponding to the minimum flow segment, the delivery efficiency of the water pump combinations corresponding to the other N-1 flow segments is greater than or equal to 70% (preferably greater than or equal to 75%), and the total number of water pumps is the least; all the water pump combinations in any preferred scheme obtained are connected in parallel to obtain an energy-saving pump group.

[0012] Furthermore, in step 2, the air conditioning water pipe system resistance is calculated according to formulas (1) to (4):

[0013] H=H1+H2 (1)

[0014] H1=λv 2 / (2d) (2)

[0015] H2=ξv 2 / twenty three)

[0016] v=Q / S (4)

[0017] Among them, H is the system resistance; H1 is the resistance along the way; H2 is the local resistance; λ is the friction resistance coefficient; v is the pipeline flow velocity; d is the pipe diameter; ξ is the local resistance coefficient; Q is the system flow rate.

[0018] Furthermore, in step 4, when selecting the water pump type and water pump combination, the rated flow of the water pump combination is greater than or equal to the flow upper limit of the corresponding curve segment; the head of each water pump in the water pump combination is greater than or equal to the resistance upper limit of the corresponding curve segment.

[0019] The present invention provides an energy-saving pump group design method based on the pipeline characteristics of the air-conditioning variable water volume system, and replaces step 5' with step 5:

[0020] Step 5′, count the number of times each flow rate appears within the full flow range of the air-conditioning water pipe system, and obtain the actual water pump delivery efficiency corresponding to each flow rate in different segmentation schemes according to the water pump delivery efficiency curve; calculate the total energy consumption of the water pump within the full flow range of the air-conditioning water pipe system in each segmentation scheme according to the number of times each flow rate appears, the system resistance, and the actual water pump delivery efficiency; connect all the water pump combinations in the segmentation scheme with the smallest total water pump energy consumption in parallel to obtain an energy-saving pump group.

[0021] Furthermore, in step 5′, the total energy consumption of the water pump is calculated as follows:

[0022] W=Σ[(ρ·Q i ·H i / η i )·Δt i ] (5)

[0023] Where: ρ is the water density; Q i is the i-th flow; H i is the system resistance corresponding to the i-th flow value; η i is the actual delivery efficiency of the pump at the i-th flow rate; Δt i is the number of hours when the i-th flow occurs.

[0024] An energy-saving pump set based on the pipeline characteristics of an air-conditioning variable water volume system is obtained by adopting the above design method.

[0025] Preferably, it also includes an inlet collecting pipe and an outlet collecting pipe. Each water pump is connected to the inlet collecting pipe through an inlet branch pipe and to the outlet collecting pipe through an outlet branch pipe. An electric butterfly valve is provided on the outlet branch pipe. The water pumps in the same water pump combination are controlled in linkage with the electric butterfly valve.

[0026] Preferably, the water inlet branch pipe and the water inlet manifold, and the water outlet branch pipe and the water outlet manifold are connected by downstream three-way pipe fittings.

[0027] Preferably, the water inlet flow rate of the water inlet manifold and the water inlet branch pipe is 1 to 2 m / s, preferably 1.5 m / s.

[0028] Preferably, the water inlet manifold, water inlet branch pipes, water outlet manifold and water outlet branch pipes are made of galvanized seamless steel pipes or galvanized spiral welded steel pipes.

[0029] The technical principle of the present invention is: in the traditional air-conditioning pump group design, since the air-conditioning load is in a partial load condition most of the time, that is, the air-conditioning water pipe system is in a partial flow operation state most of the time, the water pump head is much greater than the system resistance, and the summer water pump and the winter water pump are not used for each other, and the utilization rate of the standby water pump is also extremely low. Therefore, the traditional method will not only waste the delivery capacity of the water pump, but also waste a lot of electric energy. To this end, the present invention proposes an energy-saving pump group and a design method based on the pipeline characteristics of the air-conditioning variable water volume system, that is, by counting the full flow range of the air-conditioning water pipe system, the full flow range is divided into multiple flow sections to represent multiple working conditions, and the corresponding water pump is selected according to the flow section to form a water pump combination with different flow gradients, so that the water pump frequency conversion range is reduced, so that the water pump is always in a high efficiency range. At the same time, the summer water pump and the winter water pump are used for each other, and the utilization rate of the standby water pump is improved.

[0030] Compared with the traditional design method, the present invention has the following beneficial technical effects:

[0031] 1) The present invention considers summer load and winter load together in design, selects multiple groups of water pumps with different flow rates and different lifts in parallel, forms a water pump combination with different flow gradients, starts water pumps with corresponding flow ranges during operation, and makes the water pumps operate in a high efficiency range under various flow rates (i.e., various air conditioning loads); the number of water pumps does not increase or increases very little, and the construction cost does not increase or increases very little;

[0032] 2) The energy saving of the energy-saving pump group of the present invention is mainly reflected in three aspects: under variable water volume conditions, the water pump always operates within a high efficiency range (high efficiency means energy saving); an electric butterfly valve is arranged on the water outlet branch pipe of the water pump to replace the check valve + manual butterfly valve, thereby saving the resistance of the check valve (reducing resistance can reduce the power of the water pump); the flow rate of the water inlet manifold of the pump group is controlled at about 1.5m / s, and the tee pipes of the inlet and outlet water manifolds and the water inlet branch pipe are arranged as downstream tees to reduce resistance (reducing resistance can reduce the power of the water pump).

[0033] 3) All components of the energy-saving pump group are produced in factories. In addition to the great energy-saving advantage, the present invention also has the advantages of improving project quality and shortening construction period, and has a relatively broad market application prospect. The market size of air-conditioning water pumps is relatively large, and relatively huge power-saving benefits can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a bar chart showing the summer cooling load range and occurrence time of a project.

[0035] Figure 2 This is the water pump efficiency curve.

[0036] Figure 3 This is the piping characteristic curve of the air conditioning variable water volume system.

[0037] Figure 4 This is a schematic diagram of the air conditioning energy-saving pump group.

[0038] Figure 4 In the figure: 1-the first group of water pumps; 2-the second group of water pumps; 3-the third group of water pumps; 4-the fourth group of water pumps; 5-water inlet manifold; 6-water outlet manifold; 7-downstream three-way pipe fitting; 8-water inlet branch pipe; 9-manual butterfly valve; 10-water inlet pressure gauge; 11-water outlet branch pipe; 12-water outlet pressure gauge; 13-electric butterfly valve; 14-flexible joint. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0040] Implementation method 1;

[0041] The present invention provides an energy-saving pump group design method based on the pipeline characteristics of an air-conditioning variable water volume system, comprising the following steps:

[0042] Step 1, according to the hourly load of the air-conditioning water pipe system throughout the year, the hourly flow of the air-conditioning water pipe system throughout the year is obtained, and the full flow range of the air-conditioning water pipe system is obtained according to the maximum and minimum flow rates;

[0043] The lower limit of the flow rate in the entire flow range is the minimum flow rate among the hourly flows throughout the year, and the upper limit of the flow rate is the maximum flow rate among the hourly flows throughout the year; the various tos of the hourly flows throughout the year constitute the flow point values ​​within the entire flow range.

[0044] Step 2, according to the most unfavorable end of the air conditioning water pipe system, calculate the air conditioning water pipe system resistance at different flow rates within the full flow range (including summer and winter), and draw a system resistance-flow curve (i.e., a characteristic curve of the air conditioning variable water volume pipe system);

[0045] Since the air conditioning load is at partial load most of the time, that is, the air conditioning water pipe system is at partial flow most of the time, the system resistance also changes accordingly. The system resistance H is the sum of the along-the-way resistance H1 and the local resistance H2, that is:

[0046] System resistance: H = H1 + H2 (1)

[0047] Along the way resistance: H1 = λv 2 / (2d) (2)

[0048] Local resistance: H2 = ξv 2 / twenty three)

[0049] v=Q / S (4)

[0050] Among them, λ is the friction resistance coefficient, v is the pipeline flow velocity, d is the pipe diameter; ξ is the local resistance coefficient, considering the most unfavorable loop; Q is the system flow;

[0051] After calculating the system resistance, it is not difficult to find that the system resistance and flow have a parabolic relationship, which can be expressed as H = SQ 2 (S is the system resistance constant). Theoretically, the curve starts from the origin of the coordinate system. However, after considering the most unfavorable terminal pressure difference, the origin of the system resistance and flow rate curve moves upward during actual operation, forming Figure 3 The parabola-like curve passing through points A, B, C, and D is also called the air conditioning variable water volume piping system characteristic curve (or the water system piping operation curve). Figure 3 The curve that intersects the system resistance-flow curve is the pump delivery efficiency curve (please refer to Figure 2 ), the intersection of the two is points A, B, C, and D, and the filled area represents the flow range that can be actually controlled by the water pump combination corresponding to a certain flow segment.

[0052] Step 3, dividing the full flow range of the air conditioning water pipe system into N flow sections, and dividing the system resistance-flow curve obtained in step 2 into N curve segments according to the obtained N flow sections, and obtaining multiple division schemes; 3≤N≤5;

[0053] See also Figure 3 Assuming that the flow range is divided into N = 4 flow segments, the system resistance-flow curve can be divided into 4 curve segments. For the convenience of explanation, the upper limit points of the 4 curve segments are marked as A, B, C, and D points in descending order, so the 4 curve segments can also be expressed as AB segment, BC segment, CD segment, and D segment.

[0054] Step 4: for each segmentation scheme, according to the delivery efficiency curves of different water pumps, select the water pump type and water pump combination that meet the flow rate and resistance requirements of each curve segment in the corresponding segmentation scheme;

[0055] Before selecting a pump type and pump combination, you need to first investigate the rated flow and head of existing pumps on the market, and obtain the delivery efficiency curve of each pump. When selecting a pump type and pump combination, the rated flow of the pump combination is greater than or equal to the upper flow limit of the corresponding curve segment; the head of each pump in the pump combination is greater than or equal to the upper resistance limit of the corresponding curve segment. A pump combination refers to a pump combination consisting of 1, 2 or more pumps that meets a certain curve segment. Generally speaking, the types of pumps in the pump combination are the same.

[0056] Step 5, select the preferred scheme from multiple segmentation schemes: except for the water pump combination corresponding to the minimum flow segment, the delivery efficiency of the water pump combination corresponding to the other N-1 flow segments is greater than or equal to 70% (preferably greater than or equal to 75%), and the total number of water pumps is the least; all water pump combinations in any preferred scheme are connected in parallel to obtain an energy-saving pump group.

[0057] The present invention can provide a variety of segmentation schemes when dividing flow segments, but the water pump selection is performed for each segmentation scheme, which puts too much burden on the design. It is better to first provide a relatively simple segmentation scheme, and then optimize it step by step. In fact, a variety of segmentation schemes can be obtained during the optimization process. For example, the system resistance-flow curve is initially evenly divided into N=4 curve segments. According to the delivery efficiency curves of different water pumps, the water pump type and water pump combination that meet the first curve segment (AB segment) are first selected in order from large flow to small flow; the rated flow of the first group of water pumps meets the flow upper limit of the first flow segment, the head meets the resistance upper limit of the first curve segment, and the delivery efficiency of the first group of water pumps at the lower flow limit is greater than or equal to 70% (preferably greater than or equal to 75%); the corresponding water pump combination is marked as the first group of water pumps;

[0058] Although point B has been divided and the curve segment has been preliminarily segmented, if the efficiency of point B is much greater than 70% of the first group of water pumps, it means that the efficiency variation range of this section is too small, which will cause the flow variation range of the BC section to be too large; if the efficiency of point B is less than 70% of the rated flow of the first group of water pumps, it means that the water pump delivery efficiency is too low, which is inconsistent with the idea of ​​high-efficiency operation described in the present invention. Therefore, after determining the first group of water pumps, we may take the flow rate corresponding to the delivery efficiency of the first group of water pumps of 70% (data close to 70% such as 71%, 72% can also be used as the boundary) as the flow rate at point B, that is, redetermine point B and divide the second curve segment; the flow rate lower limit and resistance lower limit of the first curve segment (AB segment) are used as the flow rate upper limit and resistance upper limit of the second curve segment (BC segment), and then select the second and third groups of water pumps in the same way; take the flow rate lower limit (such as the flow rate corresponding to the delivery efficiency of the third group of water pumps of 70%) and resistance lower limit of the third group of water pumps (CD segment) as the flow rate upper limit and resistance upper limit of the fourth group of water pumps, and re-divide the fourth curve segment (D-segment). The flow segment corresponding to the fourth group of water pumps accounts for a very small proportion of the full flow range. Even if there is a part of the flow corresponding to the delivery efficiency lower than 70%, the power loss is small, so it is no longer subdivided to reduce the number of water pumps. The reason why 70% to max% (max% indicates the maximum delivery efficiency of the water pump) is chosen as the delivery efficiency range of the water pump combination when dividing the curve segments is because a too small range of water pump delivery efficiency will result in too many water pumps, which is uneconomical. Therefore, in addition to high efficiency, this method also adds another design principle, that is, the total number of water pumps is the least.

[0059] Therefore, the aforementioned steps 3-5 can also be expressed as follows: the entire flow range of the air-conditioning water pipe system is evenly divided into N flow segments, and the system resistance-flow curve obtained in step 2 is preliminarily divided into N curve segments according to the obtained N flow segments, 3≤N≤5, and marked as i=1, 2, ..., N curve segments in order from large flow to small flow; then, according to the delivery efficiency curves of different water pumps, the water pump type and water pump combination that meet the flow and resistance requirements corresponding to the first curve segment are selected, and the flow rate when the delivery efficiency of the first group of water pumps is Y (Y≥70%) is used as the flow upper limit of the second curve segment, and the second curve segment is re-divided; and so on, the i=1, 2, ..., N-1 groups of water pumps are obtained; the i=N group of water pumps is no longer subdivided according to Y≥70%; finally, all water pump combinations in any design scheme with the least total number of water pumps are connected in parallel to obtain an energy-saving pump group.

[0060] Implementation method 2;

[0061] In addition, the present invention also provides another energy-saving pump group design method based on the pipeline characteristics of the air-conditioning variable water volume system, replacing step 5 with step 5′:

[0062] Step 5′, according to the hourly flow rate of the air-conditioning water pipe system throughout the year (including summer and winter), the number of occurrence times of each flow rate in the full flow rate range is counted, and the water pump delivery efficiency corresponding to each flow rate is obtained according to the water pump delivery efficiency curve; according to the number of occurrence times corresponding to each flow rate, system resistance, and water pump delivery efficiency, the total energy consumption of the water pump in the full flow rate range of the air-conditioning water pipe system in each segmentation scheme is calculated; all water pump combinations in the segmentation scheme with the smallest total water pump energy consumption are connected in parallel to obtain an energy-saving pump group.

[0063] Among them, the total energy consumption of the water pump is calculated as follows:

[0064] W=Σ[(ρ·Q i ·H i / η i )·Δt i ] (5)

[0065] Where: ρ is the water density; Q i is the i-th flow; H i is the system resistance corresponding to the i-th flow rate; η i is the actual delivery efficiency of the pump corresponding to the i-th flow rate; Δt i is the number of hours when the i-th flow occurs.

[0066] The present invention can provide a variety of segmentation schemes when dividing flow segments, but it is too burdensome to select a water pump for each segmentation scheme. It is better to first provide a relatively simple segmentation scheme, and then gradually optimize it. In the optimization process, multiple segmentation schemes can actually be obtained. For example, the full flow range is first evenly divided into N = 4 flow segments, and then combined with the number of hours of occurrence of each flow segment (that is, each load segment), and the system resistance and water pump delivery efficiency corresponding to each flow, the range of the flow segment is adjusted to obtain a segmentation scheme with the minimum total energy consumption of the water pump when N = 4. The adjustment method is as follows: For example, when a certain flow point is in the first flow segment, the corresponding actual delivery efficiency of the water pump is 70%. If the number of hours of occurrence of the flow point accounts for a small proportion, then it can be considered reasonable to divide the flow point into the first flow segment, and its impact on the total energy consumption of the water pump is very small; if the number of hours of occurrence of the flow point accounts for a large proportion, then dividing the flow point into the second flow segment will improve the water pump delivery efficiency and reduce the total energy consumption of the water pump. Similarly, the partitioning schemes with the minimum total energy consumption of the water pump can be obtained when N=3 or 5, and the three schemes are compared, and the scheme with the minimum total energy consumption of the water pump is selected as the best scheme.

[0067] There are many flow point values ​​in the full flow range. If statistics are calculated based on each flow point, the calculation cost will be high. You can use the method of drawing a bar chart to divide the full flow range into many small flow intervals (for example, 20 to 30, which can be referred to Figure 1 ), the number of occurrence times is counted according to the small flow interval, and then an approximate optimal solution is determined according to implementation method 2, thereby saving computing costs.

[0068] In short, the first method is based on the premise of ensuring that the total number of water pumps is consistent with the number of water pumps in the traditional design, the water pump delivery efficiency is improved, and compared with the traditional design method, its cost remains basically unchanged or even lower; the second method is based on the premise of minimizing the total energy consumption of water pumps, and the water pump selection is more refined, and the water pump delivery efficiency is further improved. Even if the number of water pumps increases slightly, the electricity cost savings brought about by the improvement of water pump delivery efficiency will be greater than the increase in water pump cost.

[0069] See also Figure 4The present invention also provides an energy-saving pump group based on the pipeline characteristics of the variable water volume system of the air conditioner, including a water pump combination obtained by the above-mentioned design method, a water inlet manifold, a water outlet manifold, a water inlet branch pipe, a water outlet branch pipe, an inlet reducer, an outlet reducer, an inlet flexible joint, an outlet flexible joint, a water inlet pressure gauge, a water outlet pressure gauge, an angle low-resistance filter (if it is a pull-out system, it is a 90-degree elbow here), a manual butterfly valve, and an electric butterfly valve; the i=1, 2, ..., N groups of water pumps are connected in parallel between the water inlet manifold and the water outlet manifold, for example, the first group of water pumps 1, the second group of water pumps 2, the third group of water pumps 3, and the fourth group of water pumps 4, each water pump The pump forms a branch line. The water pump can be a vertical pipeline pump or a double-suction pump. Each water pump is provided with an inlet reducer and an outlet reducer. The inlet reducer is connected to the water inlet branch pipe 8 through an inlet flexible joint 14, and the outlet reducer is connected to the water outlet branch pipe 11 through an outlet flexible joint 14. The water inlet branch pipe 8 of each group of water pumps is connected to the water inlet manifold 5, and the water outlet branch pipe 11 of each group of water pumps is connected to the water outlet manifold 6; each water outlet branch pipe 11 is also provided with a water outlet pressure gauge 12 and an electric butterfly valve 13, and each water inlet branch pipe 8 is also provided with a manual butterfly valve 9 (normally open), a water inlet pressure gauge 10, and a water inlet filter (using an angle low-resistance filter). The water pump and the electric butterfly valve in the same water pump combination are controlled in linkage. The water inlet branch pipe 8 is connected to the water inlet manifold 5 by a downstream three-way pipe fitting 7, and the water outlet branch pipe 11 is also connected to the water outlet manifold 6 by a downstream three-way pipe fitting 7.

[0070] The flow rate of the water inlet and outlet manifolds and the water inlet and outlet branches of the water pump is controlled at about 1.5m / s; the water inlet and outlet manifolds and the water inlet and outlet branches of the water pump are made of galvanized seamless steel pipes or galvanized spiral welded steel pipes to extend their service life; flange connection.

[0071] Traditional air conditioning water pipe system projects are generally equipped with summer water pumps, winter water pumps, summer standby water pumps, and winter standby water pumps. Combined with the project situation, most projects have 2 to 3 refrigeration hosts and 2 heating hosts, so summer water pumps are usually set to 3 to 4, and winter water pumps are 3. Taking 2 refrigeration hosts as an example, traditional projects usually require 6 water pumps. Using this energy-saving method, there are 4 refrigeration and heating hosts in total. If the annual flow range is divided into 4 flow sections, the 1st and 2 flow sections use 2 water pumps, and the 3rd and 4th flow sections use 1 water pump, a total of 6 water pumps, and the number of water pumps does not increase. Of course, the annual flow range can also be divided into 5 flow sections. Increasing the number of water pumps will improve the utilization of the water pump's delivery capacity and save electricity, but it will increase the cost accordingly. Of course, adding 1 water pump is also allowed in some projects. Although the cost of the water pump is slightly increased, the electricity bill is saved, and one increase and one decrease is also reasonable. Therefore, the present invention can set the integrated energy-saving pump group described in the present invention without increasing the number of water pumps or increasing the number of water pumps less, that is, without increasing the cost or increasing the cost very little. The advantage of forming a flow gradient type water pump combination is that it can make good use of the delivery capacity of different water pumps, so that they always operate within the high efficiency range, reducing the waste of electric energy; and it improves the utilization rate of traditional standby water pumps. In the energy-saving pump group of the present invention, the water pumps that are not in operation can be used as standby water pumps for the running water pumps, and the delivery can be completed by a combination of 1 to 2 water pumps. As for how to combine specifically, those skilled in the art can design it according to the specific situation, which will not be repeated here.

[0072] Implementation Case 1:

[0073] This case is an air conditioning water pipeline construction project, whose cold and heat sources are electric refrigeration water source heat pump units.

[0074] 1) The air conditioning pump unit obtained by the traditional design method is as follows:

[0075] According to the hourly load calculations in summer and winter and the hydraulic (resistance) calculations of the air conditioning water pipeline, the water pump is selected as follows:

[0076] Summer water pump: Rated flow: 300m 3 / h, head: 30mH2O, rated transmission efficiency: 83%, quantity: three (two in use and one in reserve); total flow: 600m 3 / h;

[0077] Winter water pump: Rated flow: 210m 3 / h, head: 25mH2O, rated transmission efficiency: 83%, quantity: three (two in use and one in reserve); total flow: 420m 3 / h;

[0078] In summer, when each water pump is running, the actual flow rate is 300~120m 3 / h, the actual conveying efficiency is 83% to 50%;

[0079] When each water pump is running in winter, the actual flow rate is 210~85m 3 / h, the actual conveying efficiency is 83% to 50%;

[0080] When the air conditioning pump group is in operation: in summer, the summer water pump is operated. When the load changes, the number of water pumps is increased or decreased or the water pump frequency is changed; in winter, the summer water pump is operated. When the load changes, the number of water pumps is increased or decreased or the water pump frequency is changed; when the load changes slightly, the water pump frequency is mainly changed, and when the load changes significantly, the number of water pumps is mainly increased or decreased; when the water pump fails, the standby water pump is operated;

[0081] 2) Using the first design method of the energy-saving pump set described in the present invention, the water pump is selected as follows:

[0082] Group 1 pumps (upper limit is Figure 3 Point A in the middle): Rated flow rate: 300m 3 / h, head: 30mH2O, rated transmission efficiency: 83%, quantity: two units;

[0083] The second group of water pumps (the upper limit is Figure 3 Point B in the figure): Rated flow rate: 210m 3 / h, head: 25mH2O, rated transmission efficiency: 83%, quantity: two units;

[0084] Group 3 pumps (upper limit is Figure 3 Point C in the middle): Rated flow rate: 290m 3 / h, head: 21mH2O, rated conveying efficiency: 83%, quantity: one set;

[0085] Group 4 pumps (upper limit is Figure 3 Point D in the middle): Rated flow rate: 180m 3 / h, head: 18mH2O, rated transmission efficiency: 83%, quantity: one set;

[0086] The first group of water pumps (2 units), the second group of water pumps (2 units), the third group of water pumps (1 unit), and the fourth group of water pumps (1 unit), a total of 4 groups of 6 water pumps, are connected in parallel to form an integrated energy-saving pump group of the cost implementation case;

[0087] When the air conditioning pump group is running, the air conditioning water pipe system flow is detected through the computer room group control, and the most unfavorable loop pressure difference is guaranteed to control the operation of the first group of water pumps, the second group of water pumps, the third group of water pumps, or the fourth group of water pumps. When the first group of water pumps is running, the other groups of water pumps will not run; similarly, when the fourth group of water pumps is running, the other groups of water pumps will not run.

[0088] The flow rate operating range (AB interval) of the first group of water pumps (2 units) is 300 to 210 m 3 / h, actual conveying efficiency: 83%~77%;

[0089] The flow rate operating range (BC interval) of the second group of water pumps (2 units) is 210 to 145 m / s. 3 / h, actual conveying efficiency: 83%~77%;

[0090] The flow rate operating range (CD interval) of the third group of water pumps (1 unit) is 290 to 180 m 3 / h, actual conveying efficiency: 83%~75%;

[0091] The flow rate operating range (D-interval) of the fourth group of water pumps (1 unit) is 180 to 85 m / s. 3 / h, actual conveying efficiency: 83%~60%;

[0092] Obviously, the actual delivery efficiency of the first to third groups of water pumps is greater than 70%, or even greater than or equal to 75%, which are all high-efficiency operations. Although some of the fourth group of water pumps will be below 70%, their corresponding flow range accounts for a very small proportion of the flow range of the entire energy-saving pump group, so no further refinement is required. The actual delivery efficiency of the first to third groups of water pumps is greater than 75%, and the total number of water pumps is equal to the traditional design, which is an optimal solution. However, it should be noted that this solution is one of the preferred solutions, not the only solution.

[0093] When the currently used water pump fails, other water pumps will be operated; for example, suppose that the first group of water pumps (2 units) are currently operating, and the total flow rate is 600-420m 3 / h, if one of the first group of water pumps is damaged and needs repair, the third group of water pumps can be operated as a replacement, that is, the other unused water pumps can be used as backup water pumps for the currently running water pumps. The difference between the energy-saving pump group obtained by the design method of the present invention and the traditional design pump group is that the summer water pump, winter water pump and backup water pump are combined to form a water pump combination with different flow gradients. For example, when the summer flow operating range is 420~300m 3 / h. In the traditional design method, two of the summer water pumps are often operated, but the actual delivery efficiency of the water pumps is low. Similarly, when the summer flow rate operating range is 210~85m 3 / h, it is often one of the summer water pumps that is in operation, the actual delivery efficiency of the pump is also low, and the standby water pump is not well utilized.

[0094] 3) Pump group energy saving analysis:

[0095] 3.1) In the traditional pump group design, the water pump runs in summer with a flow rate of 300 to 120 m3 / h. For two pumps, the flow rate range is 600 to 120 m 3 / h, actual delivery efficiency: 83% to 50%; for the convenience of comparison, the average efficiency is taken, which is 66.5%; in fact, the actual delivery efficiency of the water pump is rarely close to 83%;

[0096] Using this energy-saving method, the flow rate changes within the range of 600 to 120 m during summer operation. 3 / h, the first group of pumps (AB interval), the second group of pumps (BC interval), the third group of pumps (CD interval), and the fourth group of pumps (D interval) are operated in sequence. The average delivery efficiency of the first and second groups of pumps is 80%, the average delivery efficiency of the third group of pumps is 79%, and the average delivery efficiency of the fourth group of pumps is 79% (the flow range in summer is 180~120m 3 / h, rated flow rate of the fourth group of pumps is 180m 3 / h frequency conversion to 120m 3 / h, the efficiency drops from 83% to 75%), so the average efficiency of the energy-saving pump group is (80+80+79+79) / 4=79.5%;

[0097] Compared with the traditional summer water pump, the energy-saving pump set obtained by the method of the present invention has an actual delivery efficiency of the summer water pump increased by about 79.5%-66.5%=13%;

[0098] 3.2) In the traditional pump group design, the water pump operation in winter: flow rate 210~85m 3 / h, 2 units, actual delivery efficiency: 83% to 50%; for the convenience of comparison, the average efficiency is taken, which is 66.5%. It is also rare for the actual delivery efficiency of the water pump to be close to 83%;

[0099] With this energy-saving method, the second group of pumps (BC interval), the third group of pumps (CD interval), and the fourth group of pumps (D interval) are operated in sequence. The average delivery efficiency of the second group of pumps is 80%, the average delivery efficiency of the third group of pumps is 79%, and the average delivery efficiency of the fourth group of pumps is 71.5% (the flow range in winter is 180~85m 3 / h, rated flow rate of the pump at point D is 180m 3 / h frequency conversion to 85m 3 / h, the efficiency drops from 83% to 60%), so the average efficiency of the energy-saving pump group is (80+79+71.5) / 3=76.8%;

[0100] Compared with the winter water pump in the traditional design, the actual delivery efficiency of the winter water pump in the energy-saving pump group obtained by the method of the present invention is improved by about 76.8%-66.5%=10.3%;

[0101] According to the load and time ratio of summer and winter (the temperature difference of supply and return water in winter and summer is considered the same), summer / winter is about 1:0.48. If this energy-saving method is adopted, the average energy-saving rate of the water pump of the air conditioner in summer and winter is: 12.12%. The energy saving is relatively considerable.

[0102] Implementation Case 2:

[0103] This case is an air conditioning water pipeline construction project, whose cold and heat sources are electric refrigeration chillers + gas hot water boilers.

[0104] 1) The air conditioning pump unit obtained by the traditional design method is as follows:

[0105] According to the hourly load calculations in summer and winter and the hydraulic (resistance) calculations of the air conditioning water pipeline, the water pump is selected as follows:

[0106] Summer water pump: Flow rate: 400m 3 / h, head: 30mH2O, rated transmission efficiency: 85%, quantity: three (two in use and one in reserve);

[0107] Winter water pump: Flow rate: 170m 3 / h, head: 20mH2O, rated transmission efficiency: 85%, quantity: three (two in use and one in reserve);

[0108] In summer, when each water pump is running, the flow rate is 400~160m 3 / h, actual conveying efficiency: 83%~50%;

[0109] In winter, when each water pump is running, the flow rate is 170~70m 3 / h or lower, actual transmission efficiency: 83% to 50% or lower;

[0110] 2) Using the first design method of the energy-saving pump set described in the present invention, the water pump is selected as follows:

[0111] The first group of pumps (AB section): rated flow: 400m 3 / h, head: 30mH2O, rated transmission efficiency: 85%, quantity: two units; meet 100% to 70% flow rate usage;

[0112] The second group of water pumps (BC section): rated flow: 280m 3 / h, head: 24mH2O, rated transmission efficiency: 85%, quantity: two; meet 70% to 43% flow rate;

[0113] The third group of water pumps (CD section): rated flow: 340m 3 / h, head: 20mH2O, rated transmission efficiency: 85%, quantity: one unit; meet the use of 43% to 20% flow rate (taking into account the use of maximum load in winter);

[0114] The fourth group of water pumps (D-section): rated flow: 160m 3 / h, head: 15mH2O, rated conveying efficiency: 85%, quantity: one set; meet the use of 20% to 10% flow rate;

[0115] The first group of water pumps (2 units), the second group of water pumps (2 units), the third group of water pumps (1 unit), and the fourth group of water pumps (1 unit) total 4 groups of 6 water pumps, which are connected in parallel to form the integrated energy-saving pump group of this implementation case;

[0116] When the air-conditioning pump group is running, the flow of the air-conditioning water pipe system is detected through the computer room group control, and the most unfavorable loop pressure difference is guaranteed to control the operation of the first group of water pumps, the second group of water pumps, the third group of water pumps, or the fourth group of water pumps.

[0117] The flow rate operating range of the first group of water pumps (2 units), actual flow rate: 400~280m 3 / h, actual conveying efficiency: 83%~77%;

[0118] The flow rate operating range of the second group of water pumps (2 units), actual flow rate: 280~170m 3 / h, actual conveying efficiency: 83%~77%;

[0119] The flow rate operating range of the third group of water pumps (1 unit), actual flow rate: 340~160m 3 / h, actual conveying efficiency: 83%~75%;

[0120] The flow rate operating range of the fourth group of water pumps (1 unit), actual flow rate: 160~70m 3 / h, actual conveying efficiency: 83%~52%;

[0121] Obviously, the actual delivery efficiency of the first to third groups of water pumps is greater than 70%, or even greater than or equal to 75%, which are all high-efficiency operations. Although some of the fourth group of water pumps are below 70%, their corresponding flow range accounts for a very small proportion of the flow range of the entire energy-saving pump group. When the current water pump fails, other water pumps are operated (can be used in combination);

[0122] 3) Pump group energy saving analysis:

[0123] 3.1) Traditional pump design, summer water pump operation: flow rate 400~160m 3 / h, two units, the flow rate range is 800~160m 3 / h, actual transmission efficiency: 83% to 50%; for the convenience of comparison, the average efficiency is taken, which is 66.5%;

[0124] Using this energy-saving method, the flow rate changes in the range of 800 to 320 m during summer operation. 3 / h, the first group of pumps (AB interval), the second group of pumps (BC interval), the third group of pumps (CD interval), and the fourth group of pumps (D interval) are operated in sequence. The average delivery efficiency of the first and second groups of pumps is 80%, the average delivery efficiency of the third group of pumps is 79%, and the average delivery efficiency of the fourth group of pumps is 79% (160-120m 3 / h, rated flow rate of the fourth group of pumps is 160m 3 / h frequency conversion to 120m 3 / h, the efficiency drops from 83% to 75%), the average efficiency of the four stages is (80+80+79+79) / 4=79.5%;

[0125] Compared with the traditional summer water pump, the energy-saving pump set obtained by the method of the present invention has an actual delivery efficiency of the summer water pump increased by about 80.5%-66.5%=14%;

[0126] 3.2) In the traditional pump group design, the water pump operation in winter: actual flow rate: 170~70m 3 / h or lower, actual transmission efficiency: 83% to 50% or lower; for the convenience of comparison, the average of 83% to 50% efficiency is taken, which is 66.5%;

[0127] Using this energy-saving method, according to the third group of pumps (CD interval) and the fourth group of pumps (D- interval), the average delivery efficiency of the fourth group of pumps is 66.5% (160~70m 3 / h), then the average efficiency of the energy-saving pump group is (79+66.5) / 2=72.8%;

[0128] Compared with the winter water pump in the traditional design, the actual delivery efficiency of the winter water pump in the energy-saving pump group obtained by the method of the present invention is improved by about 72.8%-66.5%=6.3%;

[0129] According to the summer / winter load and supply / return water temperature difference ratio (the winter supply / return water temperature difference is twice that of the summer), the summer / winter ratio is about 1:0.35. If this energy-saving method is adopted, the average energy-saving rate of the air-conditioning water pump in summer and winter is: 12.0%, which is quite considerable.

[0130] The one-to-one setting of water pumps and hosts is a common method for efficient computer rooms. Since the refrigeration host has a flow protection requirement, the flow is generally controlled at no less than 40% of the rated flow. Therefore, when the required flow is less than 40%, the water pump will not change frequency. The pump group can open a water pump corresponding to two hosts, so that the water pump is still running at a high efficiency point. As analyzed above, when the water pump flow is frequency-converted to 40% of the rated flow, the delivery efficiency drops from 83% to 50%, and the average delivery efficiency is about 66.5%. At 80% flow, the efficiency is 79%. Since high-efficiency computer rooms usually use magnetic suspension refrigerators, and magnetic suspension refrigerators have the highest efficiency when the cooling capacity is 50% to 20%, as shown in Table 1 below, the water pump frequency conversion to low flow is still a lot of operation time, so the average delivery efficiency calculated above is actually high. Although the one-to-one setting of water pumps and hosts can save about two elbows and two tees of resistance, the increase in power consumption caused by the decrease in water pump efficiency can offset the reduction in power consumption caused by the increase in elbows and tees. That is, although the energy-saving pump set of the present invention has an additional elbow and a tee, the error of the above average delivery efficiency is basically offset. Therefore, compared with the one-to-one arrangement of the water pump and the main engine in the traditional design, the energy-saving pump set of the present invention can improve the energy saving rate by more than 12%.

[0131] Table 1 Refrigeration capacity of the main engine at different efficiencies

[0132]

[0133] Then, the water pump outlet in the traditional air conditioning cold (hot) water pipeline system is generally equipped with a check valve and a butterfly valve. The check valve relies on the deadweight of the valve disc to check, so the resistance is relatively large, with a resistance coefficient of 5 to 12, and the resistance is usually 1mH2O, accounting for 1 / 30 of the system resistance = 0.033 = 3.3% (based on the water pump head 30mH2O). The closing time of the slow-closing check valve is 5 to 60 seconds (adjustable). The closing time of the electric butterfly valve is also 5 to 60 seconds (adjustable). The closing time of the electric butterfly valve is basically the same as the closing time of the slow-closing check valve. Replacing the check valve with an electric valve can reduce the system resistance (the butterfly valve resistance coefficient is 0.16), and the energy saving rate is about 3%.

[0134] The flow rate of the inlet and outlet water collecting pipes and the water inlet and outlet pipes of the water pump is controlled at about 1.5m / s. The tee is a downstream tee, and the water pump inlet filter is an angle low-resistance filter, all of which can reduce water resistance.

[0135] In summary, the comprehensive energy-saving rate of the energy-saving pump set of the present invention is above 15%, which has great energy-saving benefits. Using this design method and energy-saving pump set, based on the 14 billion square meters of public buildings in the country, 10% of which adopt water system air conditioning, using the present invention, according to a rough estimate, according to the energy saving of 15%, about 1.5 billion degrees of electricity can be saved; using an electric butterfly valve to replace the check valve + butterfly valve on the water outlet branch of the water pump, it is roughly estimated that about 300 million degrees of electricity can be saved, and the cost is basically the same.

[0136] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any modification or replacement of the technical solution made by other technicians in this professional field should be included in the scope of the claims of the present invention as long as it does not deviate from the connotation of the technical solution of the present invention.

Claims

1. A method for designing an energy-saving pump set based on the pipeline characteristics of an air-conditioning variable water volume system, characterized in that: The steps include: Step 1, according to the hourly load of the air-conditioning water pipe system throughout the year, the hourly flow of the air-conditioning water pipe system throughout the year is obtained, and the full flow range of the air-conditioning water pipe system is obtained according to the maximum and minimum flow rates; Step 2, according to the most unfavorable end of the air-conditioning water pipe system, calculate the resistance of the air-conditioning water pipe system at different flow rates within the full flow range, and draw a system resistance-flow curve; Step 3, dividing the full flow range into N flow segments, dividing the system resistance-flow curve obtained in step 2 into N curve segments according to the obtained N flow segments, and obtaining multiple segmentation schemes; 3≤N≤5; Step 4: for each segmentation scheme, according to the delivery efficiency curves of different water pumps, select the water pump type and water pump combination that meet the flow rate and resistance requirements of each curve segment in the corresponding segmentation scheme; Step 5, select the optimal scheme from multiple segmentation schemes: except for the water pump combination corresponding to the minimum flow segment, the delivery efficiency of the water pump combinations corresponding to the other N-1 flow segments is greater than or equal to 70%, and the total number of water pumps is the least; all the water pump combinations in any preferred scheme obtained are connected in parallel to obtain an energy-saving pump group.

2. The design method according to claim 1, characterized in that: In step 2, the air conditioning water pipe system resistance is calculated according to formulas (1) to (4): H=H1+H2 (1) H1=λv 2 / (2d) (2) H2=ξv 2 / 2 (3) v=Q / S (4) In the formula: H is the system resistance; H1 is the resistance along the way; H2 is the local resistance; λ is the friction resistance coefficient; v is the pipeline flow velocity; d is the pipe diameter; ξ is the local resistance coefficient; Q is the system flow rate.

3. The design method according to claim 1, characterized in that: In step 4, when selecting the water pump type and water pump combination, the rated flow of the water pump combination is greater than or equal to the flow upper limit of the corresponding curve segment; the head of each water pump in the water pump combination is greater than or equal to the resistance upper limit of the corresponding curve segment.

4. The design method according to any one of claims 1 to 3, characterized in that: Replace step 5 with step 5′: Step 5′, counting the number of times each flow rate appears within the full flow range of the air conditioning water pipeline system, and obtaining the actual delivery efficiency of the water pump corresponding to each flow rate in different segmentation schemes according to the water pump delivery efficiency curve; According to the number of occurrence times corresponding to each flow rate, system resistance, and actual delivery efficiency of the water pump, the total energy consumption of the water pump within the full flow range of the air conditioning water pipeline system in each segmentation scheme is calculated; All water pump combinations in the segmentation scheme with the minimum total water pump energy consumption are connected in parallel to obtain an energy-saving pump group.

5. The design method according to claim 4, characterized in that: In step 5′, the total energy consumption of the water pump is calculated as follows: W=Σ[(ρ·Q i ·H i / or i )·Δt i ] (5) Where: ρ is the water density; Q i is the i-th flow; H i is the system resistance corresponding to the i-th flow rate; η i is the actual delivery efficiency of the pump at the i-th flow rate; Δt i is the number of hours when the i-th flow occurs.

6. An energy-saving pump set based on the pipeline characteristics of the air conditioning variable water volume system, characterized in that: The method is obtained by adopting the energy-saving pump group design method based on the pipeline characteristics of the air-conditioning variable water volume system as described in any one of claims 1 to 5.

7. The energy-saving pump set according to claim 6, characterized in that: It also includes an inlet manifold and an outlet manifold. Each water pump is connected to the inlet manifold through an inlet branch pipe and to the outlet manifold through an outlet branch pipe. An electric butterfly valve is provided on the outlet branch pipe. The water pumps in the same water pump combination are controlled in linkage with the electric butterfly valve.

8. The energy-saving pump set according to claim 7, characterized in that: The water inlet branch pipe and the water inlet collecting pipe, and the water outlet branch pipe and the water outlet collecting pipe are connected by downstream three-way pipe fittings.

9. The energy-saving pump set according to claim 6, characterized in that: The water inlet flow rate of the water inlet manifold and the water inlet branch pipe is 1-2 m / s.

10. The energy-saving pump set according to claim 6, characterized in that: The water inlet manifold, water inlet branch pipes, water outlet manifold and water outlet branch pipes are made of galvanized seamless steel pipes or galvanized spiral welded steel pipes.

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