Main advantages of the SPRATL concept
The devices(1) are SPRATL engines, organized and
exploited in the configurations which are going to be developped ;
thus, as evoked on the page of presentation, they bring significant improvements in the domain of Stirling's engine, thanks to :
- a lot more rigorous follow-up of the (P,V) diagram (P : pressure of the fluid, V : volume of the
fluide),
- the possibility to isolate nearly completely the hot parts and the cold parts of the device (1) ,
- the use of a simple and perfectly isolated regenerator (RGN),
allowing excellent thermal exchanges, and without considerable losses
by lamination for the fluid which circulates inside with an
unidirectional out-flow,
- the exploitation of the character "rotary and bi-level with inegal volume" of the PRATL engines
(à Piston Rotatif Annulaire TriLobique) (2,2F,2C)
invented by Pascal HA PHAM.
Recall of the features of PRATL engines
As illustrated on the figure 3L, a generic PRATL machine (2,2F,2C)
is composed of a bi-arched core (NBA), of a rotary annular trilobic
piston (PRA) and of a cover (CAR) of which the internal shape is the
trajectory of the extremities of the trilobic piston (PRA) during
its different sliding and rotating motions. When the piston (PRA) turns
and slides around the bi-arched core (NBA), and inside the cover(CAR),
a bi-level structure appears,
with 2 families of moving rooms :
- internal level : small rooms
(PC1,PC2,PC3) between the internal faces of the piston (PRA) and those
of the core (NBA),
-
internal level : big rooms (GC1,GC2,GC3) between the external
faces of the rotary piston (PRA) and the internal of the cover (CAR).
By calling VM the maximum volume of one of these 6 rooms, and Vm its
minimum volume, the behaviour for any room amounts in practice to
cycles in 3 times, of type :
- exhaust time « R
», volume VM->Vm
- intake time
« A », volume Vm->VM
- transportation time at the
constant maximum volume « V=VM »
As well for small rooms (PC1,PC2,PC3) as for big rooms (GC1,GC2,GC3), Vm can be zero. The maximum volume of the big rooms is greater than the one of the small rooms and their ratio is programmed by the geometry of the piston (PRA) as described in the demand 07.6157 set-down at the INPI by Pascal HA PHAM.
Exploitation with the Stirling's cycle
The present invention uses an even number N of PRATL
machines (2) ; N/2 of them are hot because heated to temperature Tc,
and N/2 are cold because cooled to temperature Tf. Each cold machine is
connected to a hot machine with one or several regenerators (RGN).
As shown on
figures 2A to 2F, the connection of 2 machines (2F,2C),
one cold and the other one hot, via a
regenerator (RGN), gives the typical structure
of the device (1) ; more elaborated cases are foreseeable.
As illustrated on figures 3A and 3B, in the cold
PRATL machine (2F) are arranged 8 holes for unidirectional
circulation of the coolant fluid:
- LUGFHG : hole opening the big cold room of the top and left side,
- LUGFHD : hole opening the big cold room of the top and right side,
- LUGFBG : hole opening the big cold room of the bottom and left side,
- LUGFBD : hole opening the big cold room of the bottom and right side.
- LUPFHG : hole opening the small cold room of the top and left side,
- LUPFHD : hole opening the small cold room of the top and right side,
- LUPFBG : hole opening the small cold room of the bottom and left side,
- LUPFBD : hole opening the small cold room of the bottom and right side.
In the same way for the hot PRATL machine(2C), as shown on the figures 3C and
3D :
- LUGCHG : hole opening the big hot room of the top and left side,
- LUGCHD : hole opening the big hot room of the top and right side,
- LUGCBG : hole opening the big hot room of the bottom and left side,
- LUGCBD : hole opening the big hot room of the bottom and right side.
- LUPCHG : hole opening the small hot room of the top and left side,
- LUPCHD : hole opening the small hot room of the top and right side,
- LUPCBG : hole opening the small hot room of the bottom and left side,
- LUPCBD : hole opening the small hot room of the bottom and right side.
The connections described below make work the device (1) as a Stirling's motor in the hypothesis where the rotary annular trilobic pistons (PRA) are contra-rotary and start initially as shown on the figure 3I.
The
regenerator(RGN) grants the transfers of the coolant fluid between the PRATL machines (2F) and (2C)
thanks to 4 pipes rolled up in helical, as illustrated on the
figure 2E :
- the first connects LUGCHD to
LUGFBG,
- the second connects LUGCBG to
LUGFHD,
- the third connects LUPFHG to LUPCBD, et,
- the fourth connects LUPFBD to LUPCHG.
These 4 external connections to
(2F,2C) systematically join rooms of same nature (except their opposed temperatures) and whose volumes exactly vary
in an opposed way : thus, the achievement of isochoric stages of the
Stirling's cycle is perfect (as well at small volume Vmin as at
big volume Vmax) and makes itself through a very efficient regenerator
(RGN) (see ‘principle and
advantages of the regenerator’). The 4 another connections are internal connections for each machine :
- cold PRATL machine (2F)
o connection of LUGFHG to LUPFHD
o connection of LUGFBD to LUPFBG
- hot PRATL machine (2C)
o connection of LUPCHD to LUGCHG
o connection of LUPCBG to LUGCBD
These 4 connections systematically join rooms at
same temperature, the one big and the other one small, and whose the
volumes vary in an opposed way, but not at the same speed : the
istothermal transfers
Vmax<->Vmin of the Stirling's cycle are therefore achieved (as
well in relaxation/compression as hot or cold temperatures).
All these connections and the direction of the
out-flows to obtain a motor are summed up on figures 3E and 3F. The
figure 3F shows that inside the regenerator, it is possible to make a
junction between LUGCHD and LUGCBG, as well as a bifurcation towards
LUGFBG and LUGFHD (the same way for LUPFHG,LUPFBD and LUPCBD,LUPCHG).
In this last configuration, the regenerator will
have only 2 pipes, browsed by a continuous unidirectional flux of
fluid. Otherwise,
the sense of course of a pipe to the other is opposite, what
allows the regenerator, with simple hoses, to be an almost-perfect
temperature exchanger for the cold and hot
fluids passing in transit between (2F) and (2C) in order to achieve
their heating and cooling isochoric stages (2->3 and 4->1).
When one wishes a working in Stirling's receptor,
in order to have a heat pump, or a refrigerator, under the condition to
provide a mechanical work, the previous connections remain valid, but :
- the sense of rotation for the machines is inverted, thus,
- the sense of out-flow for all fluids are inverted too.
The figures 3G and 3H sum up all the connections and the senses of
out-flow for the fluid to obtain a SPRATL receptor with the device (1).
So, the previous connections make work the SPRATL machine as a Stirling's
receptor in the hypothesis where trilobic pistons (PRA) are contra-rotary and initially start as illustrated on figure 3J .
The previously exposed connections and the
contra-rotary character are only one possibility among many others :
they don't restrict in anything the possible configurations between the
cold and hot machines. The unique condition to respect is that
inside every machine, every piston (PRA) is initially in the
position described in figure 3N and turns to the same speed. Whatever
is the relative orientation of the machines (2F,2C) and/or their sense
of rotation, one can always find a combination of connections to have
a SPRATL motor or receptor in conformity with the device (1)
In series and in parallel arrangements of several machines (2F,2C)
The previous description has shown the basic
working with 2 PRATL machines (2,2F,2C), the one cold (2F), and the
other one hot (2C). The figure 3O illustrates the subsets
(2F) et (2C) or a device (1) seen as independant funtional blocks :
- for the cold PRATL machine
(2F) :
o 2 external entries for the fluide
into the big rooms,
o 2 external exits for the fluid through the smal rooms, and,
o some internal circulations of
fluid, either by displacement of the annular rotary piston (PRA),
either by connection via a hose.
- for the hot PRATL machine (2C) :
o 2 external exits for the fluide through the big rooms,
o 2 externals entries of fluide
into the small rooms, and,
o some internal circulations of fluid, either by displacement of the annular rotary piston (PRA), either by connection via a pipe.
So it is possible to built a SPRATL motor in conformity with the device (1) with an even number N of
machines (2), of which N/2 subsets (2F) and N/2 subsets (2C), as well as N regenerators
(RGN1,RGN2,RGN3,RGN4,RGN5,RGN6…) with the connecting rules described on figure 3P for N=6, and on figure 3Q for N=4.
The essential rule is to put, between 2 consecutives machines
(2F) and (2C), 2 connecting pipes to make circulate the fluid in two
opposed senses ; it is required to grant the exchange of temperatures
of the regenerator (RGN).
The machines (2,2F,2C) can be transversely mounted
(arrangement in parallel) or longitudinally (arrangement in series), as
illustrated respectively on figures 2I and 2J in the case of N=4. From
this example, one can comfortably generalize
all the longitudinal and transverse structures for all even number
N superior or equal to 4 as suggested on figures 3P and 3Q.
Finally, to have a Stirling's receptor in conformity
with the device (1), it will be sufficient to reverse the sense of
rotation of the machines (2,2F,2C): thus,
all out-flows of fluid of the figure 3O will be reversed and, while
providing mechanical work to the device (1), this one will behave like
a refrigerator (to the levels of the machines (2F)) or a heat pump (to
the levels of machines (2C))..
