Research On Energy-saving Of Series-parallel Water Supply Mode In High-rise Buildings

Along with implementation of the "energy saving and emission reduction" policy, the technologies and equipments of water supply on energy-saving get more and more attention. Now frequency control pump in parallel water supply mode is mostly used in high-rise building, it sets a holding tank to storage inlet water, then pumps of different districts uptake water from the holding tank respectively and pressurized it to users. Although it is relative energy-saving in this water supply mode, the pump always works at inefficient zone under low peak flow, which will cause a lot of energy waste. In this paper, a new-style energy-saving technology called series-parallel water supply mode was studied based on present frequency control pump in parallel water supply mode.The principle of series-parallel water supply mode can be described as follows: a small tube is connected from outlet pipe of lower area pump to the inlet pipe of higher area pump, so that pumps of both areas can be seen as working in parallel under peak flow, while working in series under low peak flow. In this case, pressure of lower area pump can be added into higher area pump effectively to increase the inlet pressure of higher area pump. When the water pressure and flow rate is constant, the frequency conversion pump rotational speed will drop along with the inlet pressure elevates, which will decrease the higher area pump head as well as the energy consumption.In this paper, energy-saving effect of series-parallel water supply mode under peak flow and low peak flow was studied by comparing the traditional frequency control water supply mode based on field test, the analysis to energy-saving impact factors of series-parallel water supply mode as well as its economic and technical analysis were also carried out.Experimental results shows that: compared to traditional frequency control water supply mode, energy-saving rates of water supply series-parallel water supply mode can reach 39.29% ~ 45.43% under low peak flow, 11.86% ~ 14.11% under peak flow, energy-saving effect is very obvious, especially under low peak flow. The energy saving effect of series-parallel water supply mode is in connection with higher area pump flow, connected pipe flow and tank water level. The smaller the higher area pump flow, the larger the connected pipe flow, the higher the tank water level, the higher the energy-saving rate is. The primary factor of energy saving effect is higher area pump flow, connected pipe flow is in the next place and then the tank water level.The tank in series-parallel water supply mode makes sure the normal water supply to users when municipal pipe network fails, which enhances the continuity and security of water supply systems, but also avoids municipal pipe network pressure drop caused by pump directly connected with municipal pipe network. The connected pipe flow is too small to affect the flow and pressure of users in lower area. The series-parallel water supply mode shows convenient transformation and low cost with large benefit, so it is suitable for transformation of traditional frequency control water supply mode.