| In recent years,the state has introduced a number of higher education policies to encourage colleges and universities to cultivate more talents with higher quality to meet the needs of the development of the times.The need of higher education for the development of the party and the state is more urgent than ever.The student dormitory is an important place for students to study and live.The establishment of a reasonable and reliable water supply system to meet the basic needs of students’ study and life is of great significance to the cultivation of outstanding talents in our country.At present,the design requirements for the balance of outflow between floors of public washroom dormitory buildings are not detailed enough in the current regulations of our country.In actual use,there are problems such as uneven flow distribution among floors in the same water supply area during peak water consumption,insufficient water pressure on the upper floor,small or no outflow,overpressure outflow from the lower floor,and poor water comfort for students.In view of this "outflow imbalance" problem,this paper conducts a study on the outflow balance between floors in public washroom dormitories.The main research contents are as follows:(1)Research based on hydraulic calculation of building water supply system,the differential pressure formula at the inlet of any two-layer branch pipe of the two water supply methods is obtained.Comparing and calculating the pressure difference between the layers of the upward-feeding and downward-feeding water supply systems,the conclusion is drawn: The pressure difference at the entrance of the branch pipe between floors depends on the distance of the riser between floors and the sum of local head losses and the height difference between floors.For the downward-feeding water supply system,it is recommended to appropriately increase the diameter of the vertical and main pipes,for the upward and downward water supply system,it is recommended to appropriately reduce the diameter of the vertical and main pipes.This is more conducive to reducing the pressure difference at the inlet of the branch pipe between floors,thereby facilitating the balance of the outflow between floors.(2)In order to obtain the dynamic pressure value when the average outflow of the taps on the branch pipes of each layer meets the rated flow specified in the "Design Standard for Water Supply and Drainage of Buildings" GB 50015-2019(hereafter referred to as "Building Water Standard")while the water supply percentage of different numbers of taps is 100% at the same time and the relationship between the inlet pressure and the outlet flow of each layer of branch pipes,an experimental model of the water supply system was built.Fitting the measurement data to obtain the relationship between the pressure and the outlet flow when the faucets with different numbers of branch pipes are fully opened respectively.Further,the dynamic pressure values corresponding to the rated flow rate specified in the specification for the outlet flow rate of branch 6,5,4,and 3 faucets are 0.129 MPa,0.134 MPa,0.140 MPa,and 0.146 MPa,respectively.Aiming at the phenomenon of overpressure outflow,the method of selecting decompression measures is analyzed.(3)Based on Flowmaster fluid simulation software,the feasibility of the software is verified from the calculation of outflow and head loss.Take a 6-storey public washroom dormitory building as an example to model the water supply system(5 washbasins are set in branch pipes on each floor),based on the incompressible steady state calculation,it is found that after the decompression measures are applied to the floors with overpressure outflow,the total outflow of the top floor increases from the original 0.714L/s to 0.742L/s,an increase of 3.9%.It is concluded that the decompression measures for the branch pipes of the floors with overpressure outflow can improve the flow conditions of the most unfavorable floors,and can improve the reliability of water use on the most unfavorable floors while saving water and energy.Based on the incompressible transient calculation,it is found that compared with the branch pipe without decompression,the implementation of decompression measures can reduce the maximum pressure of water hammer by about 17.2%,and make the violent oscillation of the pressure stabilize within 2s after closing the valve,which can effectively protect the water supply system piping and equipment to improve water supply safety.(4)Combined with engineering practice,the design of the living water supply system of the C1# student dormitory building of a new campus dormitory building construction project of a university(the second phase of the project)was completed.By simplifying the calculation formula of the existing pressure relief orifice aperture,a formula for calculating the aperture diameter of the decompression orifice that is more suitable for precise decompression of branch pipes is obtained.It is calculated that the apertures of the pressure relief orifice plates required at the inlets of the branch pipes on the 1st,2nd,4th and 5th floors are 0.0109 m,0.0121 m,0.0106 m and0.0115 m respectively.By installing a pressure relief orifice to eliminate the excess pressure on the overpressure outlet floor,the outflow rate of the original overpressure outlet floor has reached the rated flow rate of 0.9L/s,the outflow of the most unfavorable floors in each water supply area has increased,the increase of the outflow of the 3rd floor is about 2.1%,and the increase of the outflow of the 6th floor is about 2.2%.After the water supply system is put into use,the decompression investment cost can be recovered in about two months,and the decompression measures are set for the water supply system,which can save 14.75% of water every year.The conclusions obtained in this paper can not only provide ideas for the design of similar buildings in the future,but also provide reference for the renovation of existing buildings and the compilation of industry norms. |
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