Gas flow and volume thoughts
Jan 11, 2021 16:35:23 GMT -8
Dan (Upstate NY, USA) and pigbuttons like this
Post by Solomon on Jan 11, 2021 16:35:23 GMT -8
I was messing around building a J tube core out of clay brick to play around with in the back yard and I started thinking about temperature and gas volume.
As I'm sure most of you know, gases follow this three sided law. The three sides are temperature, volume, and pressure. If you increase one side, one or both of the other sides must also increase. Same with decrease.
So I was trying to build my rocket with a consistent cross sectional area and I started to wonder. How much thought has been put into the volume of the gases at different points in the system?
Naturally, at the intake, gases are at atmospheric pressure, and we may assume that there will be only slight variations in the pressure through the system, enough to cause smoke to seep out or fresh air to seep in, and the buoyant pressure in the vertical sections, but overall, the whole system is driven by vary small differences in pressure.
The gases reach their highest temperature near the bottom to middle of the heat riser. High temperature means high volume, and fast speed to move that volume through the system.
Gases have cooled significantly, several hundred degrees before they get to the manifold, and continue to cool traveling through the mass, receiving a little extra heat before going up the chimney if the chimney bottom is near the barrel. Exiting the chimney, the gas volume or flow is much lower than it was in the heat riser.
I guess I was thinking about this because of reading a thread about a guy trying to figure out why his heater wasn't working and questions about the space from the top of the heat riser and the inside top of the barrel. And I have observed many cases in reading threads and designs of the heat riser being far below the upper inside of the bell and it not being an issue.
I'm wondering, those of you who have more experience in systems and troubleshooting, have you noticed the pinch points coinciding with temperature and volume transitions? Could there be some optimization done with that in mind or has it already been done? I'm not one of those chuckleheads who looks at an RMH design and says "I could do that better." I'm one who wants to know how it works and what parts are the most important not to screw up.
I'll be building my first inside permanent one here in the next month or so.
As I'm sure most of you know, gases follow this three sided law. The three sides are temperature, volume, and pressure. If you increase one side, one or both of the other sides must also increase. Same with decrease.
So I was trying to build my rocket with a consistent cross sectional area and I started to wonder. How much thought has been put into the volume of the gases at different points in the system?
Naturally, at the intake, gases are at atmospheric pressure, and we may assume that there will be only slight variations in the pressure through the system, enough to cause smoke to seep out or fresh air to seep in, and the buoyant pressure in the vertical sections, but overall, the whole system is driven by vary small differences in pressure.
The gases reach their highest temperature near the bottom to middle of the heat riser. High temperature means high volume, and fast speed to move that volume through the system.
Gases have cooled significantly, several hundred degrees before they get to the manifold, and continue to cool traveling through the mass, receiving a little extra heat before going up the chimney if the chimney bottom is near the barrel. Exiting the chimney, the gas volume or flow is much lower than it was in the heat riser.
I guess I was thinking about this because of reading a thread about a guy trying to figure out why his heater wasn't working and questions about the space from the top of the heat riser and the inside top of the barrel. And I have observed many cases in reading threads and designs of the heat riser being far below the upper inside of the bell and it not being an issue.
I'm wondering, those of you who have more experience in systems and troubleshooting, have you noticed the pinch points coinciding with temperature and volume transitions? Could there be some optimization done with that in mind or has it already been done? I'm not one of those chuckleheads who looks at an RMH design and says "I could do that better." I'm one who wants to know how it works and what parts are the most important not to screw up.
I'll be building my first inside permanent one here in the next month or so.