Graphical way of sizing a storage tank

  • Thread starter TSN79
  • Start date
The attachment shows an example from a book on how to size a hot water storage tank (for tap water). During the 24h period a total of 55 kWh is used. The red curve shows the variation in usage along the period. The slope of the green lines is determined by the heat source's power, in this case 3,5 kW, which manages to heat up 55 kWh in 10 hours. Tangents are then placed along the curve as shown in the topmost example to determine how much water must be stored.

My question is this; how do I know where exactly to place the tangents? The book shows the topmost placing in this case but I don't see how this is obvious. The bottom example (by me) results in more storage but how do I know that's not the correct choice...?



Insights Author
Gold Member
The tangents are separated by a distance proportional to energy, in kWh. Note that the second plot, shows two lines separated by 2 kWh.

How to place the tangent? You must know your hot water needs. How many kWh per day of hot water heating do you need? Suppose that is 29 kwh, then one 29 kWh cycle per day serves that need. However, if the temperature drops too low between cycles, it might be better to split it into 10, 10 and 9 kWh smaller cycles.

Want to reply to this thread?

"Graphical way of sizing a storage tank" You must log in or register to reply here.

Related Threads for: Graphical way of sizing a storage tank

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving

Hot Threads