Solar Steam

Yahu

I am working on a design for a solar steam system. I discovered that the solar vacuum tube technology is very exciting but it is mostly just used for hot water tank heating with radiant floor or pool heating.



Most of the systems and controllers are for those applications whereas I am doing something totally different.



I am putting heat transfer oil in my closed loop system instead of water/glycol then dumping the heat into a heat exchanger/(boiler and superheater) to drive a steam engine and generator. Waste heat from the condensation of low pressure steam would be available for heating and hot water generation but most of it will go into a chemical heat storage system I am designing. That way, at night I can reuse my waste heat for a few hours to drive the steam engine even after the sun goes down.



Most current systems don't even let you get your system to over boiling. They tend to dump waste heat to dump loads to prevent boiling your storage water tanks. I wanted to create that over heat situation and use or store every BTU output for conversion into mechanical then electrical energy.



I am looking at the properties of Zoelite for that heat storage since it can store massive heat content without energy loss (180+ kW/h*m^3) and release the stored energy rapidly so even waste heat of vaporization can be converted back into high pressure steam. Heated Zoelite absorbs the heat and released trapped water vapor that it has chemically trapped. It holds ~1/3 its weight in captured water. Once the water vapor is driven off, as long as it is kept dry, it stores the heat energy without loss. It released the heat energy when it recaptures water vapor which I will have excess low pressure steam output to kick start the reaction as the sun goes down. Now the heat storage system can also be used for an air conditioning cycle to turn solar heat energy into summer cooling.



BTW Zoelite is a common mineral that most would be familiar with as the primary ingredient of cat litter to absorb the moisture and trap oder in its pores. It is cheaply available in bulk. Granted it isn't as good as the pure synthetic forms but so what, I need a few more pounds of it to store the same amount of energy.



Is anyone here playing around with heat storage systems other then just plain water tank storage?



My background is electrical engineering on the power generation side but now I am dabbling in the mechanical side and chemical engineering for the storage. I wont have any problem with the control aspects using a PLC and sensors to control pumps and such but lack the steam experience on the control side.



It will be a short steam cycle consisting of boiler, superheater with only about 1-2 gal of water. I plan to use a 2 stage Quasi-turbine rotary steam engine prototype (16x expansion strokes/revolution) then output the low pressure steam to a pre-heat heat exchanger then dumping the excess heat of vaporization into my chemical heat storage system then to a final condenser heat exchanger (if needed) before pumping it back into the pre-heater, then boiler and super heater. I am also using heat pipe technology within my heat storage system for rapid heat distribution and recovery.