We've been very happy with the results after installing a Century CW2900 last season - especially with our savings on propane! I'm looking for ways to improve the heat transference to the house, because it seems like the unit sends a lot of heat up the stack. I'm also interested in what energy the unit could be produce.
Improving Insert Efficiency
The unit makes pretty efficient use of the fuel it uses wasting little (if any) wood based on the fine/powdery ash it produces. The Century CW2900 came with a 130 CFM blower that circulates air around the firebox along with ceramic/volcanic bricks for heat reflection/absorption in the fire box. The bricks surround the firebox on all sides but the front, and has (what I believe) is a secondary combustion/recirculation system that comes through vented pipes that run just below the brick at the top of the unit.
The question is how do you improve the heat transferred into the home? Obviously, the main issue is the ventilation and air draw of the unit. The hotter the fire, the faster the air moves up and out the flue and the more fuel the unit uses. Theoretically, the faster moving air would offer less contact time w/ the unit decreasing heat transference to the house, and sending the heat energy up and out the pipe.
Heat Sinks
In looking at the model, you would think that perhaps adding a few heat sinks to the surface of the fire box might improve heat transference to the home? Heat sinks that contact the surface at variable intervals might be a good option to avoid a 'cold fire' scenario or to bring the insert up to temp.
Storing Heat Energy
This would be a tough nut to crack. If you're absorbing the heat, say with a coil of some type wrapped around the flue pipe or something like that, you'd restrict the rate of air flow up and out the unit which would produce draft/smoke problems. I suppose it could be done with a water jacket or other heat absorbent material beyond the bricks the unit comes with (I've heard silicone is great at storing heat energy), but that creates all types of questions about heat dissipation and utilization. I suppose an air turbine could be added to the flue, but you'd have air flow issues yet again.
I guess the real question is, how can you transfer more heat from the system to the home without negatively affecting things like air flow and the operation of the unit?
Steam Turbine
I thought a really cool idea would be a water circulation and steam generation system. The secondary ignition pipes in the fire box would provide the ideal location to send a few smaller copper lines through - sort of like a radiator. The system could produce either hot water for the home or generate steam to drive a small turbine. The pressure created by the steam could draw in cold water from a tank in our crawl space based on a pressure valve. When the steam pressure is high enough, the valve would close to push the steam through the turbine (and you'd naturally throw in a few emergency pressure relief valves).
Electricity Production
I love tinkering with electronics, microboards, and alternative energy, but am just an amateur at best. Thermoelectric generators caught my eye a few months back, so I ordered a few of the el-cheapo pelletier tablets for like $4/ea. Each is a 12v 8a thermogenerator that (I'm guessing) would produce about 96w of power - just shy of 300w at peak efficiency with all 3 units. I know you need to include things like a computer fan and heat sink to keep the peltier's from getting damaged, but beyond that, all this is new to me. Wondering if anyone else has tried anything similar?
Improving Insert Efficiency
The unit makes pretty efficient use of the fuel it uses wasting little (if any) wood based on the fine/powdery ash it produces. The Century CW2900 came with a 130 CFM blower that circulates air around the firebox along with ceramic/volcanic bricks for heat reflection/absorption in the fire box. The bricks surround the firebox on all sides but the front, and has (what I believe) is a secondary combustion/recirculation system that comes through vented pipes that run just below the brick at the top of the unit.
The question is how do you improve the heat transferred into the home? Obviously, the main issue is the ventilation and air draw of the unit. The hotter the fire, the faster the air moves up and out the flue and the more fuel the unit uses. Theoretically, the faster moving air would offer less contact time w/ the unit decreasing heat transference to the house, and sending the heat energy up and out the pipe.
Heat Sinks
In looking at the model, you would think that perhaps adding a few heat sinks to the surface of the fire box might improve heat transference to the home? Heat sinks that contact the surface at variable intervals might be a good option to avoid a 'cold fire' scenario or to bring the insert up to temp.
Storing Heat Energy
This would be a tough nut to crack. If you're absorbing the heat, say with a coil of some type wrapped around the flue pipe or something like that, you'd restrict the rate of air flow up and out the unit which would produce draft/smoke problems. I suppose it could be done with a water jacket or other heat absorbent material beyond the bricks the unit comes with (I've heard silicone is great at storing heat energy), but that creates all types of questions about heat dissipation and utilization. I suppose an air turbine could be added to the flue, but you'd have air flow issues yet again.
I guess the real question is, how can you transfer more heat from the system to the home without negatively affecting things like air flow and the operation of the unit?
Steam Turbine
I thought a really cool idea would be a water circulation and steam generation system. The secondary ignition pipes in the fire box would provide the ideal location to send a few smaller copper lines through - sort of like a radiator. The system could produce either hot water for the home or generate steam to drive a small turbine. The pressure created by the steam could draw in cold water from a tank in our crawl space based on a pressure valve. When the steam pressure is high enough, the valve would close to push the steam through the turbine (and you'd naturally throw in a few emergency pressure relief valves).
Electricity Production
I love tinkering with electronics, microboards, and alternative energy, but am just an amateur at best. Thermoelectric generators caught my eye a few months back, so I ordered a few of the el-cheapo pelletier tablets for like $4/ea. Each is a 12v 8a thermogenerator that (I'm guessing) would produce about 96w of power - just shy of 300w at peak efficiency with all 3 units. I know you need to include things like a computer fan and heat sink to keep the peltier's from getting damaged, but beyond that, all this is new to me. Wondering if anyone else has tried anything similar?
