Researcher9302
Mechanical
- May 26, 2014
- 1
Hi all,
I am making a state-space model of a solar heating system. The concern I have is about modeling the hot water storage tank. The heat exchange in the tank is by natural convection (we currently dont consume water hence no water flow) and occurs as follows:
1) the hot fluid from solar collector passes through the first coil inside the tank (at the bottom part) and heats water at the bottom of the tank.
2) In the tank warm layers of water rise and colder layers go down due to densities difference.
3) This warm water then heats another coil in the middle of the tank
4) and the fluid from that secondary coil goes to the radiator to heat the space.
Currently we can measure temperature of the hot fluid leaving the solar collector, T of water at the bottom and midpoint of the tank and T of fluid leaving the radiator.
I need advice on deriving differential equations for the two states: change of temperatures of water at the bottom and midpoint of the tank. I can see in modeling papers tank is divided into several parts equal to the number of sensors, so in my case I would probably divide the tank in two parts: first part with coil 1 and second part with coil 2. So the temperature change in the first section would depend on the liquid passing through the coil and losing heat to the water, heat loss through the tank walls and conduction of heat to the next layer... Can anyone respond whether this approach makes sense or suggest a better one?
Thanks a lot!
I am making a state-space model of a solar heating system. The concern I have is about modeling the hot water storage tank. The heat exchange in the tank is by natural convection (we currently dont consume water hence no water flow) and occurs as follows:
1) the hot fluid from solar collector passes through the first coil inside the tank (at the bottom part) and heats water at the bottom of the tank.
2) In the tank warm layers of water rise and colder layers go down due to densities difference.
3) This warm water then heats another coil in the middle of the tank
4) and the fluid from that secondary coil goes to the radiator to heat the space.
Currently we can measure temperature of the hot fluid leaving the solar collector, T of water at the bottom and midpoint of the tank and T of fluid leaving the radiator.
I need advice on deriving differential equations for the two states: change of temperatures of water at the bottom and midpoint of the tank. I can see in modeling papers tank is divided into several parts equal to the number of sensors, so in my case I would probably divide the tank in two parts: first part with coil 1 and second part with coil 2. So the temperature change in the first section would depend on the liquid passing through the coil and losing heat to the water, heat loss through the tank walls and conduction of heat to the next layer... Can anyone respond whether this approach makes sense or suggest a better one?
Thanks a lot!
