House heating is the problem for countries with cold climate such as Russia, Alaska of USA and Canada. The energy consumption for heating is bigger then energy consumption for electrical home appliances.
Here is temperature graph for Novosibirsk city, Siberia, Russia:
Time period is June 2007 - June 2008.
It is possible to see that summer temperature is about 25oC, winter temperature is about -20oC, mean temperature during year is about 0 oC.
Because of skin-effect beginning from some depth underground the temperature is keep fixed. It is mean year temperature 0 oC. This big underground heat reservoir can be used for air heating inside house.
I works like refrigerator. It cool underground soil and heat water in heat accumulator. Heated water is used for radiators and for shower, in kitchen etc. The energy is come from the wind and from 0 oC underground soil. Propeller axis is horizontal because compressor is fixed and can not be moved.
This system is effective because:
- there is no intermediate energy carrier (electricity)
- both wind energy and 0 oC underground soil heat energy are used
- heat exchanger is used
The problems to be solved:
- Skin-effect calculations
- estimate underground radiators sizes that can provide necessary heat flux.
- radiators structure
- estimate propeller sizes that can provide necessary power.
- propeller structure with movable blades
- heat exchanger draft and estimations
- heat accumulator draft and construction
- estimate house temperature isolation properties
- temperature inside house balance calculation
- estimate electricity power consumption for control electronics, valves turnings, small pumps.
I am finding investor for this works. The investor will be used technologies that will be developed. It is possible to develop business using this technologies. I. e. it will be company that make heat energy efficient systems for private houses. Such technologies will be more and more competitive compare with fossil fuels heating with time. Because fossil fuels price began increase several years ago. And the price will be increased more.
I made skin effect simulation
Soil parameters was taken:
specific heat c=800 J/(kg*K)
density rho=2000 kg/m^3
heat conductivity k=0.07 W/(m*K)
Calulated value of skin effect depth is L=sqrt(2*k/(rho*c*w))=0.66m
where w is frequency of years. w=2*pi/(365*24*3600)
Here is the result of simulation:
3d simulation with boreholes:
It is 10 m boreholes. 8 boreholes around house. Each borehole has -20 cel degree, it is evaporator.
Borehole diameter increased in about 10 times to have faster calulation.
But this artificial increasing is taken in to account in calulations. It is simulation of 6 years.
Depth: 10 m
Radius: 5 sm
Only quarter of all geometry is calculated because of symmetry.
Power from all 8 boreholes:
It is problem of small power just 160 W when house need about 10kW heat. It is because of bad heat conductivity of soil.
To solve this problem it is possible to increase soil conductivity by add stuctures from metal or concrete in to the soil .
Or use water reservoir, river, ground water as heat source.