CA1146361A

CA1146361A - Heat recovery from an internal combustion engine for supplementary power

Info

Publication number: CA1146361A
Application number: CA000358747A
Authority: CA
Inventors: James L. Marshall
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-21
Filing date: 1980-08-21
Publication date: 1983-05-17

Abstract

Heat Recovery from an Internal Combustion Engine for Supplementary Power ABSTRACT:
Approximately two thirds of the energy of the fuel entering an internal combustion engine is dispersed in the form of heat. Prior inventions indicate methods of utilizing a portion of this heat, but by requiring substant-ial changes to the internal design of the internal combustion engine, and/or its mode of operation.
The invention herein recovers a larger portion of the waste heat by employing a heat pump cycle to elevate the temperature of low grade heat.
Furthermore, the methods of heat recovery and utilization do not require internal design changes to the internal combustion engine; and so are applicable to existing engines. This invention can therefore save more fuel than previous methods;
and can do do on either existing or future intern-al combustion engines.

Description

11~6361 Heat Recovery from ~n Internal Combustion Enginefor SupplementQr~ Power, It i9 known that approximately(one~th~rd of the fuel energy in an lnternal combustion engine i8 given o~f Q~ heat in the exhaust gases; and a similar amount of heat i~ carr-ied away by the engine coolant. This invention relates to the reco~ary of heat from both the exhaust gases and englne coolant o~ any internal combustion engine, includlng diesel engines,to pro~ide supplementary power, such as by heating a n uid to drive a steam or vapour turbine. ~here i8 a hig~
temperature stage o~ heat recovery ~nd a lower temperatvre stage. Heat from the lower tempeI~ture Btage i9 elevated in temperature by a heat pump cycle and then delivered to the high temperature stage.
Related patents on thi3 sub~e¢t may be described a~
follows s -Combined gas turbine, ~team turbine sy~tem~ ~avebe~n propo~ed in Unite~ Sta~es Patent to Miller, No.

2, 678, 531 and No. 2,678,532 of May 16, 1954, wherein steam is combined with combu~tion gases in the 9am9 combu~tion chamber, to cool the combu~tion gases prior to their lntro-duction 1nto the tur~ine.
There i~ a United State~ Patent 3,385,565 to Aguet of August 15, 1967 wherein a combustion chamber ~or pressur-ized gas and air includes a superheater whose steam drivas a ~eparate steam turbine; the combustion gases drlving a separate turbine; and the exhaust ga9 from the ga~ turbine preheats the liquid. The steam enters the combustion chamber at two locations, both fed ~rom the expanded steam exiting from the steam turbine.
A C~adian Patent No. 998,843 i88ued 76 - 10 - 26 to M~gneault, de~¢ribes a comb~ned gQs and steQm motor compri~ing two engine~ operatively connected to Jointly drlve a power ~haft; a combustion chamber ln 3aid motor hav-ing ignition means therein and a boiler mean~ therein. Thu~
the boiler i8 contained within the combustion chamber and combu~tion is attained by the lgnition of pre~surlzed fuel and pre~surized air, both supplied by pre~ure tanks and pump8~ A sultable liquid such as water is conducted ~hrough ~a¢ket~ around the combustion chamber and through a condenser having a baffled tank, pump, shower and supplementary burner for pre~entlng freeze-up. ~he ¢ombu~tion gas jet n ame is directed into the pre~ure chamber of a motor to drtve ~ame, while ~team builds up, whereupon the ~taam is also directed tnto the pre~sure chamber. The mixln~ of the flulds occurs L6~61 in the pre~ure cham~er, not. ~n the combustion chamher.
In one embodiment thensteam ~nd combu~tion ga~es are conducted lnto the cylinders of a pi~ton-type engine at a pressure of abou~ 800 p.5.i. Other embodiment~ include a combined g~8 and ~team motor compri~ing two turbine~; or a ~in~Jle turblne hou~lng and a rotor ha~ng ~tenm turbine vane~ on one side and g~ ~et vane~ on the other. In both case~ the combu~t-ion chamber ha~ a boiler means therein to produce ~team to supplement the ga~ fuel. An additional embodiment i~ a rel-atively ~mall combined ~team condenserl ga8 and steam engine ~aid engine having a combustion chamber, a boiler therein, and an engin~ housing containing at least one pressure cham-ber with a mo~eable part driv~ngly connected to a power sha~t.
~hs ~pent 6te~m ie condensed and recycled ~o the boiler.
Canadian Patent No. 986,727 i~ued to ~ggmann in 76 -04 - 06 de~cribes a hybrid motor unit with energy ~torage.
In substance it i9 a method of operating an lntarnal ¢om-bust,ion engine arranged to drive a load, n~hereln a small portion of the engine power dri~e~ an air ¢ompra~sor~ the pre~suri~ed air iflnstored to meet acceleration requirement~
of the load by ~upplying ~aid ~tored air through a he~t ex¢hanger, which i~ heated by exhaust gase~ *rom the engine to an air- operated turbine in driving oonnection with the load. It clalms to provide extra power only for a¢celeration.
In Canadian Patent No. 449, 146 is~ued to Barr, June 15, 1948 i9 described an internal combu~tion compounde~
turbine, an inoluded steam turbine and a heat interchang~r which~extracts heat from the exhaust gases o~ the lowest pressure internal combustion turbine of the oompounded serie~ for rai~in~ ~tea~ wh~ch is u~ed to drive the steam turbine. The water ~upply of the heat interchanger i8 UBed to cool the compressor/s or intercooler/s, the feed water being thereby pre-heated. The ~team turbine provides ~upp-lementary power w~ t its exhau~t ~team may be condensed and returned to the feed water supply.
~ he inventlon herein differs from known inventions in the following wayst (a) It i~ adaptible to any internal combustion eng-ine, in¢luding die~el engines, and $ncluding existing engines, without significant modification to those engines.
(b) It reco~ers heat from three ~ource~s (i) e~hau~t ga~es; (ii) engine coolant and ~ili) eXhaust steam from a supplementary turb~ne.
l~;~,.

(c) It uses a heat pump cycle to raise the temprr-ature of heat sources which are at alower temperature.
(d) It uses fluid for the supplementary turbine in an independent circuit, permitting the choice of fluid for optimum functional characteris$ics.
(e) The steam or vapour turbine, utilizing the recover-ed heat, can supply power continuously, and not ~ust for for acceleration or other spadmodic loads.

Specification The drawings which lllustrate the embodiments of the invention are:
Figure 1, A schematic diagram of the heat recovery 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, ~ide 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 internal combustion engine,l, enter a heat exchanger,2, within a steam-generating boiler,3, Upon exit-ing from said heat exchanger the exhaust gases pass through a second heat exchanger,4, within an evaporator, 5, and exit at 6 to the atmosphere, directly or through a silencer.
The second flow circuit (dashed line) conducts the circulating engine coolant of the internal combustion eng-ine,l, into a heat exchanger,7, within ~irst stage evap-orator, ~ 27, from which it retu~ns to the internal com-bustion engine,l.

~.:1.46361 The third flow circuit ( dash-dot line) comprises a heat pump cycle. The heat pump fluid is compressed by compressor, 8; enters heat exchanger, 9, within boiler,

3, and then passes through ~xpansion valve, 10, or alter-native expansion turbine, 11. After expansion the heat pump fluid enters first stage evaporator, 27, From said evaporator the heat pump fluid, in a vapour state, flows into second stage evaporator, 5, via conduit 28; and from said evaporator the said fluid returns to ~ompressor, 8, via conduit 19.
The fourth flow circuit ( dash, two-dot line) conducts steam or vapour from boiler, 3, to drive a turbine, 12, or other form of engine via conduit, 2~.
The exhaust fluid from said turbine is conducted through heat exchanger, 13, ~Nithin first stage evaporator, 27;
and the condensate is returned to the boiler, 3, by pump 14, via conduit, 29. See Figs. 2 ~ 3 for operation:
In operation, exhaust gases from internal combust-ion engine, 1, flow through heat exchanger, 2, in boiler, ~,~provi~ing5direct heat to produce steam or vapour in said boiler. Upon exiting from heat exchanger, 2, the said exhaust gases, at reduced temperature, pass through a second heat exchanger, 4, in second stage evaporator 5, In said evaporator additional heat is extracted from said exhaust gases by the heat pump vapour therein. The heat pump fluid extracts heat from two other sources, namely: the coolant of the internal combustion engine, and the exhaust fluid from the supplementary turbine, 12~
when it is operating. The said engine coolant enters heat exchanger, 7, in first stage evaporator, 27, via conduit 22. Said coolant returns to said engine via conduit, 23.
The exhaust fluid from the supplementary turbine, 12, enters heat exchanger, 13, in first stage evaporator, 27, via conduit, 21. The condensate of said fluid is returned to boiler. 3, by pump, 14. The heat pump fluid, after passing through expansion valve, 10, extracts heat in the said first and second evaporator stages. The heat ~1~6361 ~ump fluid i~ then dra~r~ into compressor, 8, via conduit, vi~ cQ~auit 17, 19, where its temperature is raised; and it is e~reLle~
into heat exchanger, 9, in boiler, 3. ~he heat pum~
is the indirect mode of providing high temperature heat to boiler, 3. '~he steam or vapour produced in boiler, 3, by heat exchanger~, 2 and 9, drives supplementary turbine, or other engine, 12, via conduit, 20 and throttle, 24.
The characteristics or properties of the turbine fluid, the heat pump fluid and the engine coolant may be chosen for an optimum temperature range in the evaporator stages. The engine coolant, for example, if circulated under pressure, and/or contains ethylene glycol (anti-freeze) will have a higher boiling temperature than water alone. ~he heat pump fluid will be chosen to have an evaporating temperature below the boiling temperature of water, for example; an-d at a practical compressor pressure will have a temperature sufficiently high to add heat to the boiler, 3. The heat exchangers, 4, 7, and 13, in the evaporator stages will be designed for a low pressure drop and optimum heat transfer according to a known art.
~ he supplementary turbine, 12, may be coupled to the internal combustion engine, 1, by an automatic clutch, of known art, or bx x~px may be independent; and will have means of control and safety in accordance with known practice.
In very large internal combustion installations an expansion ~ turbine, 11, may be substiuted ~or expans-ion valve, 10. Said expansion turbine may be used as an auxiliary power source.

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Claims

The embodiments of the invention in which exclusive prop-erty or privilege is claimed are defined as follows:

1. A mechanical system to recover heat from an internal com-bustion engine; from both its exhaust gases and engine coolant, in combination, by external means, for the pur-pose of producing steam or vapour to drive a supplement-ary turbine or other mechanism or to supply heat to any heating process, such combination comprising a mechanical system which applies heat to a steam or vapour boiler;
said heat being extracted from the exhaust gases of said internal combustion engine; and from a heat pump cycle which receives heat from three lower temperature sources, namely: the coolant fluid of the said internal combust-ion engine; the exhaust gases of said internal combust-ion engine after their prior passage through a heat ex-changer in the aforesaid boiler; and the exhaust steam , vapour, or condensate from the supplementary driven tur-ine or other mechanism or heating process.

2. A mechanical system as described in Claim 1 employing a steam or vapour boiler comprising a pressure vessel con-taining a fluid; and within which is a heat exchanger con-duit to conduct the exhaust gases of the aforesaid intern-al combustion engine, and a second heat exchanger conduit to conduct the working fluid of a heat pump cycle; and having a means of controlling the steam or vapour output;
having a safety relief valve; and employing a pump to re-turn the boiler fluid to said boiler after its use in driving a supplementary turbine or other mechanism or supplying heat to any heating process.

3. A mechanical system, as described in Claim 1 employing a heat pump cycle comprising an expansion valve, a two-stage evaporator and a single stage or multi-stage com-pressor; wherein the working fluid flows through the ex-pansion valve into the two-stage evaporator and therefrom is drawn into the compressor which delivers the said work-ing fluid, at an elevated temperature and pressure, to a heat exchanger in the aforesaid boiler whence it returns to the expansion valve.

4. A mechanical system as described in Claim 1 and Claim 3 employing a heat pump cycle which includes a two-stage evaporator whose first stage contains a heat exchanger conduit which conduct the circulating coolant fluid from the aforesaid internal combustion engine; and con-tains a second heat exchanger conduit which conducts the exhaust steam or vapour or condensate from a driven supplementary turbine or other mechanism or heating process.

5. A mechanical system as described in Claim 1 and Claim 3 employing a heat pump cycle which includes a two-stage evaporator whose second stage contains a heat exchanger conduit which conducts the exhaust gases of the afore-said internal combustion engine after their exit from the heat exchanger conduit within the aforesaid steam or vapour boiler.