GB2074249A

GB2074249A - Power Plant

Info

Publication number: GB2074249A
Application number: GB8023017A
Authority: GB
Original assignee: Iweka M G O
Current assignee: Iweka M G O
Priority date: 1980-01-30
Filing date: 1980-07-15
Publication date: 1981-10-28

Abstract

The plant comprises one or more air pumps 2, the discharge from which is heated at 5 and diffused at 4 to produce a suction force that drives one or more piston or rotary expanders or turbines 1 that are connected to the diffuser of the pump either through the pump or by separate ducts. <IMAGE>

Description

SPECIFICATION Suction Compressor Expander This invention relates to a method of applying heat to the exhaust air issuing from a suction expander/pump complex, so as to increase the suction force working the expander and consequently produce net useful work. By suction expander is meant any moving mechanism that converts the energy in a gas to useful mechanical work and which mechanism could be efficiently worked by the suction action of a pump applied to its outlet duct. Thus turbines, other rotary mechanisms and reciprocating mechanisms that can be worked in the above described manner may be used, either singly or as a group combined in series and/or in parallel. This invention is therefore a heat engine in which since the moving parts are not exposed to a high temperature, the working life of the engine would be expected to be long.Also the non-moving exhaust duct can be made of heat resistant materials that will permit a good efficiency of the engine.

Referring to the drawings accompanying this specification, the principle of the invention is best illustrated by Fig. 1. Part of the cooled air which has been sucked through the expander (1) passes through the pump (2) where it is compressed and then passes to the heating means (5), where it is heated. It is then expanded in the nozzle (3) from where the jet passes through the jet pump (4).

The diffusion in the jet pump sucks more air through the expander (1). In this modification the air mass flow of the expander is greater than that of the pump.

Fig. 2 is a modification of Fig. 1 in which the flow through the nozzle (3) is maintained at subsonic velocity. In this case, the classical jet pump arrangement is not required, the nozzle (3) being continued as the diffuser (4) and both sufficing to convert heat (introduced at 5) to work and thus produce increased suction force through the expander (1). The mass flow through the expander and pump is the same, but the expander is of a higher power than the pump. This arrangement obviates the very low efficiency of a conventional jet pump: however, it has the disadvantage of allowing of only a low pressure ratio at the nozzle, since velocity there cannot be allowed to reach supersonic.This is because supersonic velocity cannot be diffused to obtain increased mass flow of air through the ducts: that is to produce increased suction upstream to the nozzle. In this arrangement, the optimum mass flow through the loaded expander, pump and nozzle is not reached until the air has become optimally heated.

When a high pressure ratio is used in the suction/expander pump machine, of the type shown in Fig. 2, the pressurized air will need to be expanded through two or more nozzles in series, in order that the nozzle velocities remain subsonic. Preferably, but not necessarily, a nozzle should have a wider diameter than any other nozzle placed upsteam to it. Fig. 3 illustrates two nozzles, (3a) and (3b) connected in series; (3a) being diffused before joining (3b), which is continuous downstream with the diffuser 4.

Fig. 4 is a modification of Fig. 2 in which no nozzle is placed downstream to the Burner (5).

Heating of the air in the diffuser 4 leaving the compressor, causes sufficient heat conversion to work, provided the pressure ratio across the expander is high. In the example illustrated in Fig.

4, in which an impulse turbine (1) is shown, velocity in the nozzle (3a) should be high and could be supersonic, but velocity in the passage (3b) and in the Pump (2) and other downstream passages must be subsonic. This modification of the invention is based on an experimental observation by the inventor, which has shown that when an expander is worked by suction, heat addition to the driving fluid down-stream to the expander produces significant conversion of heat to work in the expander, provided the pressure ratio across the expander is high and the passages for the fluid in the expander are smaller than all other passages downstream to it. Where more than one expander is used, each expander should preferably, but not necessarily, have a higher pressure ratio than any other downstream to it.

In this invention, the final diffusion, (in 4 in tbe figures) should preferably, but not necessarily, be upwards. In this case the diffusion should continue until the velocity of the issuing air is very low: for example to a valve equal to or just less than the velocity of free natural convection of air heated to the temperature of the exhaust gas.

Heating may be by internal combustion using conventional methods; or it may be by external heating of the walls of the passage around (5) in Figs. 1, 2 and 4. In this case the passage is made to have a flattened configuration, in order to expose a large surface area. Solar energy may be used for external heating if the walls form part of a solar panel. In Fig. 4, solar energy, particularly after concentration by mirrors, can be aimed through the outlet diffuser to heat blackened surfaces within the diffuser.

The above-described arrangements of compressor/expander mechanism may be used as heat pumps and refrigerators. As refrigerators, heat exchangers are used to utilize the cooled air issuing from the expander (1), in Figs. 1, 2 and 4.

Used as heat pumps, heat is introduced into the driving fluid, after it has left the expander and before it has entered the pump (2). In these cases, since the compressor/expander complex may not be able to drive itself, external source of power will have to be provided to drive the mechanisms.

In the method of this invention, the action of the pump is initiated either by a motor connected to the shaft of the pump or by hand cranking.

Thereafter, the pump may be driven by the expander which feeds back to the pump either through a common shaft or electrically from a generator driven by the expander.

In the following claims the adjective rotodynamic is used to describe rotating mechanism, for example centrifugal, axial, mixedflow and rotary pumps and impulse and reaction air turbines and rotary air motors.

Claims

Claims

(1) A method of converting heat energy to useful mechanical energy comprising one or more piston or rotodynamic air pumps, the ducted discharge from which is heated in a heating means of any standard type and passed through a diffuser, that thereby produces an increased suction force which by this suction effect alone drives one or more piston or rotodynamic air expanders being the only moving expanders in the apparatus of the method, and the cooled air issuing from their discharge ducts being fed to the pump intake or else used by means of heat exchangers to cool the air taken in by the pumps, the said pumps being coaxial with said moving expanders or else being driven by a separate motor.

(2) A method as claimed in Claim 1 in which part of the cooled air that has been sucked through expander passes through the pump where it is compressed, then heated and passed through a nozzle and a diffuser that form a standard jet pump which sucks air thrpugh the expanders.

(3) A method as claimed in Claims 1 and 2 in which the expander and pump receive different air intakes, but the air intake of the pump is cooled by the cooled discharge of the expander by means of heat exchangers.

(4) A method as claimed in Claim 1 in which all the air that has been sucked through the expander is pressurized by the pump, heated and passed through a nozzle, which nozzle is continued as a diffuser, that causes increased suction through the expander.

(5) A method as claimed in Claim 1 and 4 in which more than one nozzle connected in series are used.

(6) A method as claimed in Claims 1 and 4 in which the discharge from the pump does not pass through a further nozzle, but is simply diffused whilst being heated, the expander being placed in series and upstream to the pump, the expander being of a higher power than the pump.

(7) A method as claimed in Claim 1 to 6 in which the diffuser discharges upwards in the direction of natural convection.

(8) A method as claimed in Claims 1 to 7 in which the heating means is sunlight converted to heat by the blackened surface of the air duct of the apparatus.

(9) An apparatus for use in the method claimed in Claim 1 comprising a pump, the discharge duct of which contains a heating means, and discharges into a diffuser to which a rotodynamic expander is connected through the pump by ducts such that the air discharged from the expander forms the air intake of the pump, which said pump is either coaxial with the expander or is driven by a separate motor.

(10) The apparatus of the method as claimed in Claim 1, 2 or 9 in which the discharge duct from the suction expander bifurcates, one of the branches forming the inlet of the pump, the other branch being connected directly to the diffuser of a standard jet pump consisting of a nozzle discharging into the diffuser, the said nozzle being fed from the duct of the heating means positioned downstream to the pump.

(11) The apparatus of the method as claimed in Claims 1, 2 or 10 in which the discharge duct of the expander is not connected to the inlet duct of the pump, but in which the said discharge duct of the expander is connected to the first element of a heat exchanger and the inlet duct of the pump is connected to the second element of the said heat exchanger, thus enabling the cooled discharge from the expander to cool the inlet air of the pump.

(12) The apparatus of the method claimed in Claims 4 or 9 in which the discharge duct of the suction expander continues as the inlet duct of the pump, which pump discharges through the heating means to a nozzle that is physically continuous with the exhaust diffuser.

(13) The apparatus of the method as claimed in Claims 4 or 12 in which the nozzle at the entrance of the exhaust diffuser is replaced by two or more nozzles, each nozzle being followed by its own diffuser and each downstream nozzle preferably having a wider diameter than the one immediately upstream to it.

(14) The apparatus of the method as claimed in Claims 1 or 9 in which the exhaust diffuser contains the heating means, which on heating the air produces increased suction force across the moving expander connected in series and upstream to the pump, which said expander has a rated power two to ten times that of the pump.

(1 5) The apparatus of the method as claimed in Claims 1-14 in which the exhaust diffuser discharges upwards.

(16) The apparatus of the method as claimed in Claims 1-15 in which the heating means is a standard solar panel forming the wall of the air passage at the site of the heating means, which wall has a flattened configuration in order to expose a large surface area for external heating.

(17) The apparatus of the method as claimed in Claims 1 to 1 6 in which more than one moving expander connected in series or parallel are used.

(18) The apparatus of the method as claimed in Claims 1 to 17 in which more than one pump connected in series or parallel are used.

(19) The use of any of the open circuit apparatus of Claims 9 to 1 8 as a refrigerator by passing the cooled air discharged from the moving suction expanders through a radiator or heat exchanger in order to cool a space.

(20) Energy obtained by any of Claims 1 to 8.