LU506820B1 - Optimization design method for air conditioning duct system - Google Patents

Abstract

The present invention provides an optimization design method for an air conditioning duct system, which is suitable for a restricted space of an engineering site, gives consideration to the comfort requirement of low noise in a room, optimizes a section size of an air duct and an air port size, acquires an optimal air duct design solution which simultaneously satisfies the cost requirement and the comfort requirement, and has relatively good economic efficiency, an energy saving property and a comfort property.

Description

OPTIMIZATION DESIGN METHOD FOR AIR CONDITIONING DUCT 7906820

SYSTEM

TECHNICAL FIELD

[01] The present invention relates to the field of optimization design for ventilation and air conditioning duct systems, and in particular to an optimization design method for an air conditioning duct system.

BACKGROUND ART

[02] For air duct design of a traditional ventilation and air conditioning system, firstly, according to the requirements of a building for the ventilation and air conditioning system, the direction and section shape of an air duct are determined. Then, for the design the air duct size, an assumed flow velocity method is generally employed.

According to the design flow of each air duct, selection is made in an air duct size specification library with reference to the standardized recommended flow velocity. In engineering practice, an on-site air duct size specification library contains multiple non-standard sizes, and there are still multiple size combinations under the condition of satisfying recommended flow velocity and on-site space constraints. Although selecting the minimum size satisfying constraints can reduce the initial investment, it will increase the running cost of a wind system, which may be unfavorable from the perspective of full life cycle economic efficiency. Furthermore, in order to adapt to the complex on-site space, a local pipe section has to be reduced in size, where the flow velocity will exceed the recommended flow velocity, resulting in large regenerated noise of the air duct, which may cause the noise transmitted to a room to exceed an allowable noise level of the room and affect the indoor comfort.

SUMMARY

[03] Aiming at the defects in the prior art, the present invention provides an optimization design method for an air conditioning duct system, which solves the problems of poor full life cycle economic efficiency, too large noise and influence on 1 indoor comfort existing in the traditional air duct system design. 7906820

[04] The above technical objective of the present invention is achieved by means of the following technical means:

[05] An optimization design method for an air conditioning duct system includes the following process:

[06] step 1: building a building information modeling (BIM) model of building electromechanical integrated pipelines, drawing a preliminary air duct system BIM model, determining an air duct route, dividing each pipe section and loop of the air duct system, and giving numbers;

[07] step 2: exporting the length of each pipe section from the preliminary air duct system BIM model, establishing a database of the size of an air duct and an air port, and determining the size constraint and the flow velocity constraint of the air duct and the air port according to the restricted space of each pipe section;

[08] step 3: establishing airflow noise constraints of the air duct system;

[09] step 4, establishing a hydraulic calculation model of the air duct system;

[10] step 5: establishing an initial investment cost model of the air duct system;

[11] step 6: establishing a running cost model of the air duct system;

[12] step 7, establishing an economic efficiency optimization model considering a full life cycle of the air duct system, determining weight coefficients of the initial investment cost and the running cost of the air duct system, solving the economic efficiency optimization model on the basis of a Python+ Gurobi platform, and acquiring an optimal air duct system design solution; and

[13] step 8: importing the optimal air duct system design solution into the preliminary air duct system BIM model, updating the section size of the pipe section and the air port size, and improving model details.

[14] The present invention has the following beneficial effects:

[15] According to the present invention, on the basis of the BIM design and adapting to the restricted space of an engineering site, the full life cycle economic efficiency mathematical model considering the initial investment and running cost is established for the ventilation and air conditioning duct system, and the constraint that 2 the airflow noise of the air duct does not exceed the allowable indoor noise level is 7906820 added, such that the comfort requirement of low noise in a room is considered, the section size of the air duct, and the air port size are optimized, the optimal air duct design solution which simultaneously satisfies the cost requirement and the comfort requirement is acquired, and relatively good economic efficiency, an energy saving property and a comfort property are achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[16] FIG. 1 is a flow diagram of an optimization design method of the present invention;

[17] FIG. 2 is a hydraulic calculation case diagram of an air duct system in a restricted space;

[18] FIG. 3 is a model diagram of an air duct system in a restricted space;

[19] FIG. 4 is a sectional view of an air duct system in a restricted space; and

[20] FIG. 5 is an integrated electromechanical BIM model diagram in a restricted space.

[21] In the figures: 1-pipe section 1; 2-pipe section 2; 3-pipe section 3; 4-pipe section 4; 5-pipe section 5; 6-pipe section 6; 7-pipe section 7; 8-ventilator, 9-air handling unit; 10-wall; 11-connecting beam; 12-bracket A; 13-bracket B; 14-chilled water return pipe; 15-chilled water supply pipe; 16-cooling water return pipe; 17-cooling water supply pipe; 18-restricted space; 19-air duct system; and 20-air supply shutter.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[22] Example 1:

[23] As shown in FIG. 1, an optimization design method considering the full life cycle cost for an air duct in a restricted space specifically includes the following process:

[24] step 1: build a building information modeling (BIM) model of building electromechanical integrated pipelines, determine an air duct route, divide the air duct, 3 and give numbers. 7506820

[25] Firstly, the BIM model of the building electromechanical comprehensive pipelines is built. BIM deepening design is performed on the basis of space limitation of an existing building structure. Factors such as multi-discipline collision detection, engineering mounting space reservation, system running and maintenance space reservation, branch pipe layout, pipeline flow, and flow velocity are comprehensively coordinated. The air duct route is determined, and a preliminary air duct system BIM model is drawn. A starting node of the air duct in the preliminary air duct system BIM model is acquired, connected branch pipes, subbranch pipes and fittings are automatically searched, and the air duct system is resolved into a tree structure. Then, the air duct system is divided and numbered, marking sections as pipe section 0, pipe section 1, ..., pipe section n, ..., and pipe section N. The quantity of air ports at a tail end of the air duct system as I, I loops are numbered as Z1, Z2,..,Zi,..., and ZI. The number set of pipe sections included in loop Zi is recorded as {2,;.

[26] Step 2: determine the size constraint and the flow velocity constraint of the air duct and the air port according to the restricted space of each pipe section of the air duct system on the basis of the preliminary air duct system BIM model built in step 1, which specifically includes the following process:

[27] Firstly, the length of each pipe section of the air duct is derived from the preliminary air duct system BIM model, and a database of the size of the air duct and the air port is established. An air duct length vector is determined to be L. and

L= U Dt Ly ly L L, and Ly represent the lengths of pipe section 1, pipe section n, and pipe section N respectively. An air duct width vector is set to be W. and W=IMo Wooo Wy lw . An air duct height vector is set to be H, and H=[H He Hyly W W, and Wy represent the widths of pipe section 1, pipe section n, and pipe section N respectively. H, , H, and Hy represent the heights of pipe section 1, pipe section n, and pipe section N respectively. 4

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[28] The size of pipe section n satisfies the constraint of Formula (1) below according to the restricted space of each pipe section:

O<W <W"™ O0<H <H™ 1<n<

[29] n= n= nsN y max H"

[30] In the formula, n and n represent the maximum width and maximum height of pipe section n subjected to space constraints respectively.

[31] The size of the air duct may be expressed by Formula (2):

H = DIM -HS ,W = DIM -WS

A A

> HS, = LS WSs, =1 1I<n<N

[32] a=l a=l (2).

[33] In the formula, DIM represents a size set vector of the air duct, and

DIM = [DIM DIM >, DIM gl WS is a section width selection matrix

WSir … WS,

Ws=| © :

WS WS oe of the air duct, and Al AN /AxN HS is a section height

HS, ... HS,

HS=| : = :

HS + HS selection matrix of the air duct, and Al AN JAN Elements in

WS HS WS, . matrix and matrix are Boolean vectors. an is the element at column

N and row 4 in matrix WS , indicating whether pipe section n selects size

DIM . . Sa ue @ as the width with a value of 1 indicating yes, and a value of 0 indicating no.

HS . n a : HS a

M is the element at column and row in matrix , indicating whether . . . DIM . . Ce pipe section n select size @ as the height with a value of 1 indicating yes, and a value of 0 indicating no.

[34] A length-width ratio of the air duct section satisfies the constraint shown in

Formula (3):

max(H,,W min

[35] (HW) (3).

[36] In the formula, max(,) and min(,) represent a maximum function and a minimum function respectively. X represents a length-width ratio of the air duct section, and X=4.

[37] Then, according to the function of the building and attributes of the pipe section, it is determined that pipe section n belongs to a main pipe, a branch pipe or a subbranch pipe, an inlet of a ventilator 8 or an outlet of the ventilator 8, and then the recommended flow velocity interval and the maximum flow velocity of pipe section n are determined with reference to GB50736-2012. Pipe section n satisfies the flow velocity constraint of Formula (4):

H,-W, — H,W, _p Q max . _ —W elif v.<=—"==<v, . H =H W =W,

H, ’ Ww, else : return

[38] (4).

Vo ow,

[39] In the formula, — and 2” are a lower limit and an upper limit of the pax recommended flow velocity respectively, ” is the maximum flow velocity, and

H Ww 9, is the flow of pipe section n. " and 2” are an upper limit height and an upper limit width of pipe section n satisfying the constraints of the above Formulas (1), _- . elif (2) and (3) respectively. The second row of Formula (4) indicates that if the conditions are satisfied, a pipe diameter of pipe section n is directly assigned, pipe section n is marked as an unfavorable pipe section, and the section size constraint of pipe section n is replaced by the equality constraint: H,=H, , and W,=W, 6

; LU506820

The third row of Formula (4) indicates that if neither if conditions nor elif conditions are satisfied, the operation is terminated, and the pipeline route is planned again.

[40] An unfavorable mark vector UF of the air duct system is established according to the above determination, and UF =|UF,,---,UE,,---,UFy li

Elements in UF are Boolean variables. UF UF, and UFy are the 1st, nth and

Nth elements in the unfavorable label vector UF respectively, indicating whether to mark pipe section 1, pipe section n and pipe section N as unfavorable, where 1 indicates yes, and 0 indicates no.

[41] Step 3: establish airflow noise constraints of the air duct system.

[42] The most unfavorable sound-receiving point is determined according to the unfavorable mark number of the pipe sections of the loop, the shortest pipeline route and other conditions, the number of an air port of the most unfavorable sound-receiving point is marked as s, and the loop corresponding to the air port is recorded as branch Zs.

Then a planned mounting position of a muftling apparatus is determined at the outlet of the ventilator, and the natural noise attenuation amount DL of each component (including a straight pipe, an elbow, a tee joint, a four-way joint, a reducer, a valve and an air supply port) from the outlet of the ventilator to the most unfavorable sound-receiving point, and the regenerated noise amount IL of each component from the muffling apparatus to the most unfavorable sound-receiving point are calculated.

[43] The airflow noise from the muffling apparatus to the most unfavorable sound-receiving point is calculated, where the airflow noise at a starting point is the regenerated noise of an adjacent component downstream of the muffling apparatus, and the airflow noise at each component is obtained by means of recursive calculation according to Formula (5):

LW,-DL, IL, ay LWe=10lg10 © +107) oO

[45] In the formula, marking P at the lower right corner of the variable represents 7

. . . LU506820 the current component, and marking F at the lower right corner of the variable ;( LW, ;( ;( represents the downstream adjacent component. represents the airflow noise of . LW, . . the downstream adjacent component, and represents the airflow noise of the

DL, . . current component. represents the natural attenuation amount of noise of the

IL, downstream adjacent component, and represents the regenerated noise amount of the downstream adjacent component.

LW,

[46] If the noise at the air supply port is set as and the natural attenuation _ DLroom «+. … of room noise is set as , the airflow noise transmitted to the room satisfies

L =L — DL . . . that Wroom Wek room | LWroom is related to the size of the pipe section and the air port which are included in branch Zs. If the section width vector of the pipe section included in branch Zs is set as Wa and the section height vector is

H LW . . . . . . set as Zs ROOM is the function of the section size of each pipe section of branch Zs and the size of the air port at the tail end, as shown in Formula (6) below. The constraint of Formula (7) below shall be satisfied, otherwise, it indicates that the airflow noise is too large, and it is necessary to add a tail end muffler before entering the house.

The additional cost will be incurred.

[47] LWroom = J (Wey, Hz, FW, FH) (6), and

[48] LWroom < N Kroom (7).

NRpoom ;

[49] In the formulas, represents an allowable noise level of the room,

FW FH and S and S represent the width and the height of the air port S at the most unfavorable sound-receiving point respectively.

[50] Step 4, establish a hydraulic calculation model (namely resistance loss model) of the air duct system.

[51] Resistance of the air duct system includes two portions, namely on-way resistance and local resistance. 8

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[52] The on-way resistance and the local resistance are shown in following

Formulas (8) and (9) respectively. An on-way resistance coefficient of a pipeline is shown in Formula (20): 2

L pv _ n n

AP, = A Z— 2De,

[53] (8), 2 vp _ n

AP; - 7

[54] (9),

K 68

À, =0.1 Uo + =

[55] En BC (20).

AP, AP.

[56] In the formulas, *” and J" represent the on-way resistance and the local resistance of pipe section / respectively. P represents a fluid density, De, 2H W be =m +W) À represents an equivalent diameter of pipe section MN and (H,+W,) oon,

L, Vi | Re, and Sn represent a friction resistance coefficient, a branch pipe length, a flow velocity, a Reynolds number and a local resistance coefficient of pipe section / respectively. K represents the absolute roughness of an inner wall of the pipeline.

[57] Then, the hydraulic calculation model of each loop of the air duct system 1s shown in Formula (10) below. The loop with the largest resistance loss is identified as the most unfavorable loop, which is recorded as M. The resistance loss of the most unfavorable loop is shown in Formula (21) below.

AP, = > (AP, + AP; , )

[58] nl (10), and

AP, AP,

[60] In the formula, Zi AP, and M represent the resistance loss of 9 loop Zi, loop ZI and the most unfavorable loop respectively.

[61] Step 5: establish an initial investment cost model of the air duct system.

[62] The initial investment cost of the air duct system includes the investment cost of the air duct, air duct accessories, and the air port. 0 Un. ZL

[63] If the section perimeter of pipe section is set to be "the expanded area of pipe section ” is Sn , and S.=4L,-L, L, represents the length of pipe section 7.

[64] The mounting material cost of the air duct is calculated by using Formula (11) below:

N J

— ZL,

Com = EP ip + D Pan; NUM 1) Sr

[65] n=l j= (11).

[66] The mechanical cost of the air duct is calculated by using Formula (12) below:

N D

Come = ‚NUM + S

Pmc p mc,d mc,d n

[67] n=l m=1 (12).

[68] The labor cost of the air duct is calculated by using Formula (13) below:

I

— ZL, .

Cor = > Du NUM S,

[69] i=l (13).

Com C C f

[70] In the formulas, pm ‚PC and PP hr are the mounting material cost, the mechanical cost and the labor cost of the air duct respectively. J and J are the type number and the type quantity of auxiliary materials required for mounting the air duct respectively. and D are the type number and the type quantity of machines required for mounting the air duct respectively. is the unit price of plates of the air duct. “ “7 is the unit price of the th type of auxiliary material. Pmed is the unit price of a machine team of the “th type of machine. Pir is the unit price of

NUM a. NUM: M" labor. es med and NUM, represent the quantity of auxiliary material J the machine team quantity of machine ¢ and the worker quantity that are required per unit extended area of the air duct with the section . ZL . . . 5 perimeter of "respectively, all of which are related to the air duct section size. ” is the extended area of pipe section ”.

[71] The investment cost of the air port is shown in Formula (14) below:

I

Fi Fi Fi Fi

Cp= > (phi + pit + Pi): NUM

[72] i=l (14).

[73] In the formula, Cr represents the manufacturing and mounting cost of the

Fi Fi Fi .

Fi air port. Pu ; Pime ; Dar and NUM are the material unit price, mechanical unit price, labor unit price and quantity corresponding to the air port respectively, all of which are related to the size of the air port.

[74] The initial investment cost of the air duct system is shown in Formula (15) below:

[75] Cini — Co + Coe + Co + Cr (15)

[76] In the formula, Cini represents the initial investment cost of the air duct system.

[77] Step 6: establish a running cost model of the air duct system.

[78] Firstly, the power Power of the ventilator is calculated by using Formula (16) below:

Power = On H jan“ Qfan 71,67

[79] Jim (16). 0, . . . . H fan

[80] In the formula, is the electric motor capacity safety coefficient. 11

0 LU506820 and “17 are the fan design total pressure and design air volume respectively,

H, =6, -AP 0. =6,-0 fan ! des and Jan 2 des J and 2 are the wind pressure amplification coefficient set in view of an increase of pipe friction, and an air volume amplification coefficient considering air leakage of the air duct respectively. ies is the design flow of the air duct, which is the sum of the air volumes of all the air ports.

AP, : . . . AP, = AP, des js the design resistance loss of the air duct system, and des M Ts is the ventilator efficiency, and Mn is the transmission efficiency. . C . . .

[81] Then, the running cost "7 of the air duct system is calculated by using

Formula (17) below:

T e c - y Lower &, Nom Di run a + ry

[82] t=] (17).

[83] In the formula, T is the service life of the air duct system. I is the number

CL . Non : . of years in which the air duct system has run. run is an annual full-load equivalent . . . . . Non : running duration. If the air duct system is a constant air volume system, run is the . . . . . . N actual running duration, If the air duct system is a variable air volume system, run . . . . Er. . is the weighted annual running duration under each load rate. is the correction coefficient of the ventilator running power in the ‘th year in consideration of the p° factors such as the pipe friction increase and electric motor wear. “ ! is the electricity price of the ! th year. ” is the discount rate.

[84] Step 7: establish an economic efficiency optimization model considering a full life cycle of the air duct system shown in Formulas (18) and (19) below, where considering that a construction institution does not measure the initial investment cost and the running cost of the air duct system equally when making decisions, different weights are given to the initial investment cost and the running cost. The model is 12 solved on the basis of a Python+ Gurobi platform to acquire the optimal air duct system design solution.

I pr Chiro = WC ai + WC zn

[85] NA (18), and st. g(x)<0,f(x)=0

[87] In the formulas, subscripts of min are decision variables of the optimization problem, including an air duct width vector W, air duct height vector H | air port width vector and air port height vector FH and are a weight coefficient of the initial investment cost of the air duct system and a weight coefficient of the running cost of the air duct system respectively. is the full life cycle cost considering the initial investment cost and running cost. ” d. represents constraint conditions. < . . . . . g(9) <0 represents inequality constraints, including Formulas (1), (3), (4) and (7). f)=0 represents equality constraints, including Formulas (2), (5), (6), (8)-(17), (20) and (21).

[88] Step 8: import the optimal air duct system design solution exported from step 7 into the preliminary air duct system BIM model, update the section size parameter of the air duct and the size parameter of the air port in the preliminary BIM model, and improving model details of connecting members such as the reducer, the tee joint and the four-way joint. 13

Claims (1)

WHAT IS CLAIMED IS: 7906820

1. An optimization design method for an air conditioning duct system, comprising the following process: step 1: building a building information modeling (BIM) model of building electromechanical integrated pipelines, drawing a preliminary air duct system BIM model, determining an air duct route, dividing each pipe section and loop of the air duct system, and giving numbers; step 2: exporting the length of each pipe section from the preliminary air duct system BIM model, establishing a database of the size and price of an air duct, an air duct accessory and an air port, and determining the size constraint and the flow velocity constraint of the air duct and the air port according to the restricted space of each pipe section; step 3: establishing airflow noise constraints of the air duct system; step 4, establishing a hydraulic calculation model of the air duct system; step 5: establishing an initial investment cost model of the air duct system; step 6: establishing a running cost model of the air duct system; step 7, establishing an economic efficiency optimization model considering a full life cycle of the air duct system, determining weight coefficients of the initial investment cost and the running cost of the air duct system, solving the economic efficiency optimization model on the basis of a Python+ Gurobi platform, and acquiring an optimal air duct system design solution; and step 8: importing the optimal air duct system design solution into the preliminary air duct system BIM model, updating the section size of the pipe section and the air port size, and improving model details. 1