Design of water supply systems in buildings based on the estimation of instantaneous flow rates by the dynamic calculation method

Kazuhiko Sakamoto, Saburo Murakawa,  Daisuke Ikeda, Hiroshi Takata

2021 Symposium CIB W062

International Council for Research and innovation in Building and Construction

on line

The authors have developed the dynamic calculation method for cold and hot water supply loads in buildings. The calculation program named MSWC (Murakawa’s Simulation for Water Consumption) calculates the instantaneous flow rates in time-series with the calculation model based on people’s behavior of water usage.  Moreover, the authors have developed MSPS（Murakawa’s Simulation for Pump System) program as a sub-program to apply the fluctuation values of instantaneous flow rates calculated by MSWC program for the design of water supply systems in buildings such as booster pump system. In this paper, the authors give an overview of the MSPS program and show its application to plumbing design.
MSPS program extracts the fluctuation values of instantaneous flow rates of 5-second intervals throughout one hour including the instantaneous maximum flow rate, which is decided by the value of excess probability 0.2% in 100 simulation trials. The diagram of fluctuation values of instantaneous flow rates during the peak time zone analyzed by MSWC program is displayed on the computer screen.
The pump capacity selected by designers is illustrated on the variation diagram. The flow rate phenomena that occur beyond the selected pump capacity are shown in numerical values based on statistical processing. Therefore, the designers can easily consider the appropriate pump capacity.
In the case of dividing the number of pumps on booster pump system in buildings, it is used as a tool for designing a stable water supply system, such as calculating the frequency of stop and the accumulator capacity for the pressure drop at startup.