Note: Descriptions are shown in the official language in which they were submitted.
Improved Me-thod for Hea-t Recovery from
Internal Combustion Engines for
Supplementary Power _
It is known that approximately one third of the fuel
energy in an internal combustion engine is given off as
heat in -the exhaus-t gases; and a similar amount of heat is
carried away by the engine coo:lant. This invention relates
to -the recovery of heat from both the exhaust gases and
engine coolant of any internal combustion engine, including
diesel engines, to provide supplementary power, such as by
heating a fluid to drive a steam or vapour turbine. There
is a high temperature stage of heat recovery and a lower
temperature stage. Heat from the lower -temperature stage is
elevated in temperature by a heat pump cycle and -then del-
ivered to the high -temperature stage.
Related patents on this subject may be described as
follows:-
Combined gas turbine, steam turbine sys-tems have
been proposed in United States Patent to Miller, No.
2, 6789 531 and No. 2,678,532 of May 16, 195~, wherein
steam is combined wi-th combustion gases in the same comb-
ustion chamber, to cool the combustion gases prior to their
introduction into the turbine.
There is a United States Patent 3,385,565 -to Aguet
of August 15, 1967 wherein a combustion chamber for press-
urized gas and air includes a superheater whose steam
drives a separate steam turbine; -the combustion gases driv-
ing a separate turbine; and the exhaust gas from the gas
turbine prehea-ts the liquid. The steam en-ters the combust-
ion chamber at two locations, both fed from -the expanded
steam exi-ting from the steam turbine.
A ~anadian Patent No. 998,843 issued 76 - lo - 26
to Migneault, describes a combined gas and steam motor
comprising two engines operatively connected to jointly
drive a power shaft; a combustion chamber in said motor
having igni-tion means therein and a boiler means therein.
Thus the boiler is contained within the combustion chamber
and combustion is a~ttained by the igni-tion of pressurized
fuel and pressurized air, both supplied by pressure ~tanks
and pumps. A sui~table liquid such as water is conducted
-through jackets around the combus-tion chamber and through a
condenser having a baffled tank, pump, shower and supple-
mentary burner for preventing freeze-up. The combus-tion gas
jet flame is direc-ted in-to the presæure chamber of a motor
-to drive same, while steam builds up, whereupon the s-team
is also directed in-to -the pressure chamber. The mixing of
~the fluids occurs in -the pressure chamber, not in the com-
bus-tion chamber. In one embodimen-t -the s-team and combus-tion
gases are conducted in-to -the cylinders of a piston-type
engine a~t a pressure of about 800 p. s. i . O~ther embodimen~ts
:;nclude a combined gas and s-team mo-tor comprising two
turbines~ or a single -turbine housing and a rotor having
s-team -turbine vanes on one side and gas je~t vanes on -the
o-ther. In both cases -the combus-tion chamber has a boiler
means thereirl -to produce s-team -to supplement the gas fuel.
An addi~tiona]. embodimen-t is a relatively small combined
s~team condenser, gas and steam engine said engine having a
combus-tion chamber, a boiler therein, and an engine housing
con-taining a-t leas~t one pressure chamber with a moveable
par~t drivingly connected -to a power shaft. The spent steam
is condensed and recycled to the boiler.
~l
~ 7
Canadian Paten-t No. 986,727 issued -to Eggmann in
76 - o4 - o6 describes a h~vbrid motor uni-t wi-th energy
s-torage. In substance it is a method of operating an inter-
nal combustion engine arranged -to drive a load, wherein a
small portion of the engine power drives an air compressor;
the pressurized air is s-tored to meet acceleration require-
ments of -the load by supplying said s-tored air through a
heat exchanger, which is heated by exhaust gases from the
engine -to an air-opera-ted turbine in driving connection
with the load. It claims to provide extra power only for
acceleration.
In Canadian Patent No. 449, 146 issued to Barr, June
1~, 1948 is described an internal combustion compounded
turbine, an included steam turbine and a heat interchanger
which extracts heat from the exhaust gases of the lowest
pressure internal combus-tion turbine of the compounded
series for raising s-team which is used to drive the steam
turbine. The water supply of the hea-t in-terchanger is used
to cool the compressor/s or intercooler/s, -the feed water
being thereby pre-heated. The steam turbine provides supp-
lementary power whilst its exhaust steam may be condensed
and returned to the feed water supply.
Canadian Paten-t No. 1,112,05~ issued to Hainan, Nov.
lo, 1981 embodies apparatus to generate superhea-ted press-
ure steam, an injector-compressor apparatus utilizing the
generated steam as motive power to pre-compress the com-
bus-tion air, a jacketed cooling system of the engine,
through which the air-steam mixture from the injector-
compressor flows serving as a coolant, said mixture being
thereby superhea~ted and being rammed into the engine's
combustion space.
Canadian Patent No. 1, 146, 361 issued to James ~.
Marshall, 17 May 1983 describes a sys~tem for upgrading the
coolant heat, and ~the lower temperature portion of the
engine exhaust gases by means of a heat pump cycle. This
upgraded heat raises the temperature of circulating cond-
ensate9 in a boiler, which is then raised to steam or
vapour at higher temperature and pressure by the higher-
temperature portion of the engine exhaust gases. The said
steam is used to drive a turbine whose exhaust steam con-
tribu-tes heat to -the first s~tage of a two-stage evapora-tor
in the heat pump cycle.
The invention herein differs from known inven-tions,
excep-t for -the Marshall Pa~ten-t No. 1, 146, 361, in the
followlng ways:
(a) I-t is adap~tible to any in-ternal combustion eng-
ine, including diesel engines, and including exis-ting
engines, wi-thou-t significant modifica-tion -to those engines.
(b) It recovers hea-t ~rom -three sources: (i) exhaust
gases; (li) engine coolant and (iii) exhaust steam from
a supplemerl-tary turbine.
(c) I-t uses a hea-t pump cycle -to raise -the temper-
ature of hea-t sources which are a-t lower temperature.
(d) I-t uses fluid for the supplementary -turbine in an
independen-t circui-t, permi-tting the choice of fluid for
optimum f`unc-tional charac~teristics.
(e) The steam or vapour -turbine, utilizing the recov-
ered hea-t, can supply power con-tinuously, and no-t just for
acceleration or other spasmodic loads.
The invention herein differs from -the Marshall Paten-t
No. 1, 146, 361 in the following ways:
(a) The boiler is divided into a superheating boiler
and a low temperature boiler.
(b) The high-temperature range of engine exhaus-t
gases contribute heat to the superheating boiler, and
therefrom the lower temperature range of said exhaust gases
conduct heat to the low -temperature boiler, ins-tead of to
the heat pump evaporator.
(c) The exhaust steam from the driven turbine is con-
ducted, in a controllable amount, into ~the second s-tage,
that is, the higher temperature s~tage evaporator of the
heat pump stage instead of into the first stage evaporator.
The curren-t method in Marshall Paten-t No. 1, 146, 361
for recovering heat from the coolant and exhaus-t gases of
an engine with -the employment of a heat pump cycle uses a
single boiler; routes some of the exhaust gas heat -through
the heat pump circuit; and routes exhaust s~team from a
supplementary -turbine through -the first stage of a two-
stage evaporator. In operation -this requires that the heat
pump circuit carry some of -the exhaust gas heat. The single
boiler must have both a superheating heat exchanger and a
heat exchanger -~or liquid, and consequen-tly a large -temp-
erature gradient, and a complex design. The exhaust steam
from the driven turbine is used in the firs-t stage evapor-
ator whereas it can be more effectively used in -the second
s-tage.
The invention herein conducts -the lower temperature
portion of ~the exhaust gas heat directly into a low temp-
erature boiler which is more efficient -than directing it
through -the heat pump. Secondly the boiler is divided in-to
a superheating boiler and a low temperature boiler which
results in a lower temperature gradient; a definite div-
ision between the lower temperature and higher temperature
sections; and a less complex design. Thirdly the exhaust
s~team ~rom -the driven turbine, which is at a higher temp-
era-ture ~than the engine coolan-t, can be more effec~tively
used in -the second s~tage evapora-tor which operates a~t a
higher tempera-ture than -the firs-t s-tage. Four-thly, i-t is
found -tha-t the ra-te of ~low of steam/condensate -through -the
sys-tem is dependen-t upon -the mass of s~team which can be
superhea-ted by -the engine exhaust gases. The invention
herein provicles for a controllable by-pass valve to limit
the portion o~ the exhaus-t s-team from -the driven -turbine
entering the second s-tage evaporator o~ -the heat pump so
tha-t -the s-team produced in -the low -tempera-ture boiler can
be limi-ted -to -the amoun-t which can be adequa-tely super-
heated in -the superhea-ting boiler.
Specifica-tion
The drawings which lllus-tra-te the embodiments of
the invention are:
Figure 1, A schematic diagram of the heat recov-
ery system.
Figure 2, The assembly of the heat recovery
system and driven turbine, top view.
Figure 3~ The assembly of the heat recovery
system and driven turbine, side view.
The heat recovery system comprises four flow
circuits which are described as follows:
With reference to Figure 1, (solid line),
exhaust gases from the in-ternal combustion engine,1, flow
over the surfaces of a superheating heat-exchangert2,
within a steam-generating boiler,3, Upon exiting from said
boiler the exhaust gases pass through a heat exchanger,4,
within low-tempera-ture boiler,30, and exit at 6 to the
atmosphere, direc-tly or through a silencer.
The second flow circuit (dashed line) conducts
the circulating engine coolant of -the internal combustion
engine,1, into a heat exchanger,7, within first stage evap-
orator,27, from which it returns -to the internal combustion
engine,1.
The third flow circui-t (dash-dot line) comprises a heat
pump cycle. The heat pump fluid is compressed by compressor,
8, enters heat exchanger,9, within low temperature boiler,
30, and then passes through expansion valve,10, or alter-
na-tive expansion turbine, 11. After expansion the heat pump
fluid enters first stage evapora-tor, 27, From said evapOr-
ator the heat pump fluid, in a vapour sta~te, flows in-to
second stage evaporator, 5, via condui-t 28; and from said
evaporator the said fluid returns to compressor, 8, via
condui-t 19.
The fourth flow circuit ldash, -two-dot line) con-
ducts steam or vapour from boiler, 3, to drive a turbine,
12, or other form of engine via condui-t, 20. A portion of
the exhaust fluid from said turbine, con-trolled manually or
automatically by boiler pressure, is conducted through heat
exchanger, 13, within second s~tage evaporator, ~; the rem-
ainder is c~nducted to a condenser 31, or to a heating
process; and the condensate is returned to boiler, 30, by
pump 14, via condui-t, 29. See Figs. 2 & 3 for operation:
Opera-tion
In operation, exhaus-t gases from internal combus-tion
engine, 1, flow over hea-t exchanger, 2, in boiler, 3, via
conduit 1~ providing direc-t hea-t to superheat steam or
vapour in sald boiler. Upon exiting from boiler, 3, the
said exhaust gases, a-t reduced -tempera-ture, pass through a
hea-t exchanger 4, in -the low -tempera-ture boiler, 30 ! The
hea-t pump fluid ex-trac-ts hea-t from -two sources, namely: the
coolant of -the interna]. combus-tion engine, and the exhaust
fluid from -the supplementary turbine, 12, when i-t is oper-
a~ting. The said engine coolant en-ters heat exchanger, 7, in
firs-t stage evapora~tor, 27, via conduit 22. Said coolant
re-turns -to said engine via conduit, 23. The exhaust fluid
from -the supplemen~tary turbine, 12, enters heat exchanger,
13, in second s~tage evaporator, ~, via conduit, 21. A por-
-tion of said exhaus-t fluid is conducted to condenser, 31,
or -to a heating process, by controllable valve, 32. The
3~L9~7
condensate of said fluid is re-turned to boiler, 30, by
pump, 14.
The heat pump fluid, after passing -through expansion
valve, 10, ex-trac~ts heat in the said first and second evap-
ora-tor stages. The heat pump fluid is then drawn in-to
compressor, 8, via conduit, 19, where its temperature and
pressure are raised; and it is expelled via conduit 17,
into heat exchanger, 9, in boiler, 30. The heat pump is the
indirec-t mode of providing high -tempera-ture heat to boiler,
30. The steam or vapour superheated in boiler, 3, by heat
exchanger, 2, drives supplementary turbine, or other engine,
12, via conduit, 20 and -throttle, 2~.
The characteristics or properties of` the -turbine
fluid, the hea-t pump fluid and the engine coolant may be
chosen for an optimum -temperature range. The engine coolant9
for example, if circula-ted under pressure, and/or contains
e~thylene glycol (anti-freeze) will have a higher boiling
temperature than water alone. The heat pump fluid will be
chosen to have an evaporating temperature below the boiling
temperature of water, for example; and at a practical com-
pressor pressure will have a temperature sufficiently high
to add heat to the boiler, 30. The heat exchangers will be
designed for a low pressure drop and optimum heat -transfer
according -to a known art.
The supplementary turbine, 12, may be coupled to the
internal combustion engine, 1, by an au-tomatic clutch, of
known art, or may be independent; and will have means of
control and safety in accordance with known practice.
In very large internal combustion installations an
expansion trubine, 11, may be substituted for expansion
valve, 10. Said expansion turbine may be used as an auxil-
iary power source.
