Optimise the Tank capacity for 24* 7 water supply system

Question

Dear All, 
 To determine the tank capacity for a 24*7 water supply system with two inlets with (16 hours water supply) and one single outlet (24 hours), How to give demand allocation for the tank with two inlets using demand allocation in watergems ?

Sushma Choure · Answer

Hello Naresh, 
 Do you have pumps in the model? If yes do you want to model them as fixed speed pump or variable speed pump? Are you planning to design the tank levels based on pump operations? 
 About demands, are you applying demands directly on the tank? or demands are applied as usual on junctions or using customer elements? Tank capacity will depend upon total demand of the model, pump operations, and demand patterns for 24*7 supply system. 
 Two inlets and one outlet, is this a top filling tank? Tank with multiple inlets you should model it as PSV and set has separate inlet to false. 
 This modeling approach is explained in detail in below wiki. 
 Modeling top fill tanks and throttling inlet valves 
 Could you please elaborate your query about demand allocation, what issues you are facing in it? Demands can be applied as usual though.

Jesse Dringoli · Answer

Hi Naresh, 
 As Sushma mentioned, the tank inflow and outflow is not something you assign to the tank but rather it is calculated based on energy balance. If you have pipes between the tank and a downstream demand, the outflow from the tank will be based on the demand. If you have a pump upstream of the tank, the inflow will be based on what the pump is doing. 
 When you say "16 hours", do you mean that the pump operation is time-based? If so, see: Using "Clock Time" and "Time From Start" Controls 
 If you need further assistance, please clarify any specific questions that you have.