The technology behind the REC
Simple concept, amazing potential
The technology behind the REC has a simple concept
yet so innovative and powerful. The REC is an active heat exchanger
which transforms a part of the heat to pressure pulses of a desired
frequency. These can be used different ways to generate work (connecting
to a piston engine, a turbine, a pump, an electricity generator…).
In thermodynamic terms, the REC acts as “a closed system with a moving
boundary” that transforms an existing given temperature difference
into kinetic energy which can connect to an electric generator.
Today's external heat engines are very limited in power due to small
cylinder volumes. At nilsinside we have solved this by using very large
heat transfer areas, allowing much larger cylinder volumes which can
benefit from lower temperature differences and be built for much higher
output power than a conventional engine.
Here’s the technical explanation
The REC is a closed system that heats up and cools down
a large sliced volume efficiently, fast and repetitively, resulting
in internal pressure changes.
The illustration below shows a cross-sectional view of the REC and
its internal parts.
An inside view of the REC with the hot and cold blocks and their
respectively conducting fins in red and blue, and the electric operated
RS in brown with the quarter openings which contain the slices of
volume. The hot and the cold blocks are separated by insulating nil
blocks in transparent beige. The second nil block (placed opposite)
has been removed in order to see the RS opening.
The closed REC uses an internal “Revolving Shutter” (RS),
a pack of discs, to move the sliced gaseous volume column which is
held within a quarter of an opening called the Work Generating Volume
(WGV). The RS rotates the WGV between the conductive fins of a hot
and a cold block where they heat up/cool down quickly. This results
in internal pressure changes. Note that these are thin slices with
large area as they heat up and cool down faster than thick volumes.
To prevent unwanted efficiency leaks, the REC contains
two “nil blocks” with insulating fins placed in-between the hot and
the cold blocks. These insulating blocks prevent the simultaneous
heating up and cooling down of a part of the same volume.
The RS is not in contact with the fins and is free wheel
turned by a controller with logics and an electric stepper motor.
Although the purpose of the RS is only to move around gas, it must
be constantly controlled. This is done by the “Revolution Dynamic
Link” (RDL). The RDL software continuously adjusts the RS speed
according to input from the running application. It’s designed for
variable speed as well as a varying work load.
Here’s how the REC works, step by step:
1. The Revolution Dynamic Link (RDL) positions the opening of the RS to overlap with the hot block of the REC
2. Heat-transfer from the hot fins into the slices of gaseous volume (WGV) takes place
3. The internal pressure of the REC rises and forces the piston to move a given distance
4. The RDL turns the slices of the work generating volume to the fins on the cold side, where they will dump their heat
5. The internal pressure drops and the piston returns to its original position, i.e., pushed back the distance. The process restarts from step 1.
Still a bit of a blur?
Check out the video animation of the REC cycle: