Water Jet Pump In A New Heating System And Numerical Simulation

Water in jection pump has the advantages of easy installation, run the energy-saving, high reliability and low failure rate, and been widely used in many fields besides the heating field.This paper analyzes the basic structure and the working principle of the water jet pump, and also analyzes the three applications in the heating system which including the high and low areas directly connected system, the first and second network directly connected system, and the secondary side mixed- water heating system.This paper proposes a new heating system which using return water of the radiator system to directly supply the high and low floor radiant heating users. The supply-water of high area uses the return water of the main pipe radiator system lead by pressurizer, and take the high pressure return water of high area as driving power of low area circulating water to overcome the low area pipeline resistance.The key equipment which can provide the energy of high area return water to low area return water is the water injection pump in the high-low area connectly system,and the key technology is the coordinatly working Through the water injection pump to make the high area pressure down,and lead the low area return water inflow to return water pipeline. This system not only reduces the operation consumption, and discretion to hydraulic balance, and using the working fluid (the high area return water)with fewer flow difference to led the fluid(the low area return water),which is more feasible.This paper also derivates the calculation formulas which influence the property of water jet pump (such as the nozzle exit cross-sectional area, the best distance form the nozzle entry section of the cylindrical mixing chamber to the nozzle exit cross-sectional area, the length of the mixing chamber, diffusion tube length, etc.), and programs a visual computing software by using VB program according to these formulas which can make the operator abtain the specific dimensions of each component of the water jet pump by using each parameter after been actual measured.This paper has introduced four regulation methods of the heating system respectively, and analysises the conditions for water injection pump normal operation in four regulation methods. This paper has also made theoretical analysis and numerical simulation for the regulation method of changing supply water temperature and flow in different phases, and abtain the proper selection of the water injection pump is the precondition of the water injection pump safe and reliable operation during the heating season,the necessary operation parameter of imports and exports under the adjustment condition is the guarantee of system reliable working. This paper also puts forward adjusting method and design step of the pressure pump, water injection pump adopting the quality- flow adjustment in the new heating system. The performance parameters of pressure pump meeting the water injection pump normal operation has obtained by the example analysis,and propose the adjusting range of economic operation.Anslysised from the simulation results, water jet pump normal working is mainly affected by the import and export pressure which is not only related to performance parameters of pressure pump,but also related to the regulating mode of heating system. Most of the time of heating operation is different from the design condetion,so the performance parameters of pressure pump and the structural parameters of water jet pump of the reliable and energy conservation operation,the economic adjustment range of heating system can not be obtained only through numerical simulation during the heating periodFinally, this paper has made the energy consumption analysis for the regulation method of changing supply water temperature and flow in different phases.Pressure pump performance parameters affect operation consumption. The smallest operation consumption of water injection pump is different in different application conditions, need particular case is particular analysis. Finally the operating energy consumption of the new system was compared from the independent heating system of low area,thus reflect the advantages of water injection pump directly-connected high-low area heating system in the aspect of energy conservation and emission reduction.The new system is the supplement and extention of using the return water of high area to lead the return water of the whole main pipe, and make up the water injection pump shortage of low return water pressure because of high injection ratio.This two systems and traditional building entrance adopting water injection pump connected directly system was composed of the application domain in the heating system,which has great energy saving potential.