US1975704A - Heat pump cycle and method of operating same - Google Patents

Description

0c.2,1934; a WILKES 1,9'75,704

HEAT PUMP CYCLE AND METHOD OF OPERATING SAME Filed July 28, 1933 3 Sheets-Sheet 1 Oct. 2, 1934. I I G. WILKES 1,975,7Q4

HEAT PUMP CYCLE AND METHOD OF OPERATING SAME Fild July 28, 1933 s Sheets-Sheet 2 HEAT PUMP CYCLE AND METHOID 0F OPERA'QING SAME G. WILKES Filed July'2 8, 1935 s Shegt-Sheat a Patented Oct. 2, 1934 "UNITED STATES PATENT oarce n'iza'r rum crow sun mz'rnon or oraaarme sum 8 Claims. (01. 02-115) This invention relates to heat pump cycles, and more particularly to a method of operating such cycles and apparatus for use therein.

In operation, the ordinary heat pump cycle is 'fairly emcient so that the losses occurring in the cycle, particularly where the heat range temperature variation between evaporator and condenser elements is not great, are either unnoticed or overlooked. Attempted application of such cyclesto situations where the temperature variations are considerable both increases the inemciency of the cycle and renders this inefliciency highly noticeable. It is, therefore, obvious that where a heat pump cycle is employed in any situation where both ends of the cycle are to be employed, as for example, in modern dairy systems where the developed heat is used in pasteurization and the low temperatures in cooling the milk and formation of ice-cream and ices, the cost of operation becomes prohibitive. The decrease in efilciency is particularly noticeable where the high temperature requirements of the cycle demand use of the refrigerant at or near its critical point. This decrease in efliciency afiects the hot end of the cycle by the increase in motive power required to compress the refrigerant to v suflicient pressure for liquefaction at the higher temperatures, and aflects the cold end of the cycle by passing to the evaporator a liquid near the critical point and containing therefore almost as much heat as the vapor is capable of absorb-.

ing fora useful cooling effect.

An important object of this invention is the production of a method of operation and apparatus for use in such method of operation which will permit recuperation of at least a portion of the work availablein the saturated liquid withdrawnfrom the condenser in circulation of the refrigerant in the system.

Another general object of this invention is these high temperature differential cycles by providing a means of extracting by conversion into mechanical work, a certain portion of the sensible'liquid heat.

. A more specific object of the inventionis the combination with a reciprocating p compressor of a recuperative motor having driving connection with this compressor and having means whereby a regulated-supply of liquid withdrawn from the condenser may be evaporated therein and in evaporation release work to assist in driving the compressor. v

A still further object of the invention is the increase the effectiveness of the evaporator on g6 is equipped with a cam 19 controlling an adaptation of this recuperative principle to the rotary or gear pump type of compressor as employed in heat pump cycles.

A still further object of the invention is the adaptation of this principle to ejector cycle heat Pumps.

' These and other objects I attainby the construction shown in the accompanying drawings wherein, for the purpose of illustration, I have shown a preferred embodiment of my invention and wherein:

Fig. 1 is a semi-diagrammatic view illustrating a heat pump cycle including a reciprocating pump and incorporating my invention;

Fig. 2 is an enlarged sectional view through the recuperative motor employed in Fig. 1;

Fig. 3 is a semi-diagrammatic view showing my invention as applied to a heat pump cycle including a rotary compressor;

Fig. 4 is a detafl sectional view showing a meth- 0d of mounting the compressor and recuperative motor; and l Fig. 5 is a diagrammatic view illustrating my invention as applied to an ejector cycle heat Referring now to the drawings, and more particularly to Figs. 1 and 2, the numerals 10 and 11 indicate respectively the condenser and evaporator of a heat pump cycle, and the numeral 12 a compressor for circulating a refrigerant through the condenser-and evaporator and connected in series with the condenser and evaporator.

In accordance with my invention, 1 provide a recuperative motor generally designated at 13 and including a cylinder 14, a piston 15 reciprocating in this cylinder and having driving connection with the shaft 16 of the reciprocating compressor 12. In the present instance, the shaft 16 is shown as extended and provided with a crank 17 mount the connecting rod 1a of piston 15. The shaft haust valve 20 for cylinder 14. The exhaust chamber 21 of recupe'rative motor 13 is placed in communication with the intake of evaporator 11 while the intake of this motor is in communication with the outlet of condenser 10 through a liquid supply chamber designated at 22.

Liquid supply chamber 22 contains a suitable means for controlling the amount of liquid delivered to the motor 13. This control means is at present indicated as comprising a cam-operated tappet 23, the cam 24 of which is mounted upon shaft 16 and which tappet actuates through the lever arm 25 a'valve 26 controlling admission to the cylinder 14 of motor 13. Since the amount 9 of liquid delivered will be variable, a means for controlling to compensate for this variation is shown in float ball 27 operating through suitable leverage 28 upon a wedge element 29 inserted between sections of tappet rod 23.

It will be obvious that in operation the drive motor 30 of the reciprocating compressor will cause reciprocation of piston 15 in its cylinder. As the piston starts to move downwardly in the cylinder, vapor is expanded from the admitted charge and in expanding releases available work which is imposed against the piston, forcing the same downwardly. The pressure applied to the piston as a result of expansion of the vapor will continue with progressive expansion until the piston has reached the approximate lower limit a of its stroke, after which valve 20 will open permitting the piston to discharge the expanded gases and residual liquid to the evaporator 11 as the piston rises. The forces exerted against piston 15 thus act to assist the motor 30 in its operation and to enable the use of a much smaller motor than could be employed ordinarily.

.In Fig. 3, the application is to the rotary type compressor cycle and the numeral 31 generally designates a rotary compressor withdrawing refrigerant from an evaporator 32 and discharging the same to a condenser 33. Between the outlet of the condenser 33 and the inlet of evaporator 32 the recuperative motor 34 is disposed, the motor and compressor, as more clearly shown in Fig. 4. having a common drive and being preferably mounted in a common case 35 having an internal partition 36 separating the units. In this type of construction, advantage is taken not only of the forces generated by expansion, but likewise of the pressure of liquids delivered from the condenser 33 which are but slightly below the delivery pressures of compressor 31. Liquid delivered from the condenser to recuperative motor 34 is passed through a control chamber 37 containing means for separating the liquid from gases, at present shown as a float valve 38. This float valve co-operates with a suitable stop 39 in such manner that the valve element 40 thereof never completely closes and a slight flow of liquid will be maintained even though the supply from condenser 33 should fail. It will'be obvious that the expansion of vapor from this liquid in recuperative motor'34 and the pressure of the delivered liquid will act toassist in operation of compressor 31, thus reducing the size of the. necessary operating motor 41.

I have further incorporated an arrangement whereby the use of a viscous sealing medium such as glycerin may be resorted to in a system of this character. Separation of this medium from the gas discharged from compressor 31 is a comparatively simple matter, and, as at present shown is accomplished by a trap 42 having a liquid outlet 43 controlled by a float ball 44. This outlet discharges at the inlet of the recuperative motor 34 and the pressure of this sealing liquid will, of course. assist in the operation of the motor. From the motor, the sealing liquid is carried to the evaporator 32 in which the liquid level is maintained at or about the indicated point. The sealing liquid employed is lighter than the refrigerant and, accordingly, rises to the upper'ends of the condenser coils where it is carried off by the boiling liquid to a separator .chamber 45. From the separator chamber the refrigerant gases are conducted to compressor 31 through conduit 48 while the sealing liquid is conducted to the compressor through a conduit 47. Since the stop 48 of trap maintains the valve 49 of the trap slightly open at all times, conduit 47 is provided with a valve '50 which is closed except during operation of the compressor. Valve 50 may be controlled in any suitable manner being generally illustrated in the present instance as electrically controlled by a thermostat 51 controlling motor 41.

In Fig. 5 an ejector type heat pump cycle is illustrated. In this flgure 52 designates a boiler containing the refrigerant liquid and heated by a thermostatically controlled burner 53. Vaporized refrigerant passes from the boiler through a conduit 54 to the impeller Jet 55 of an ejector compressor 56. The outlet of compressor 56 communicates with a condenser 57 operating as a heating coil while the low pressure inlet of the ejector communicates with the outlet of an evaporator 58 operating as a chilling coil. A connection between the outlet end of the condenser coil and the inlet end of the evaporator coil, indicated at 59, includes a trap 60 which, in addition to the outlet communicating with the evaporator has a further outlet 61 permanently in communication with the outlet of condenser coil 57 through the trap chamber. While the outlet 61 might communicate directly with the outlet of coil 57, the chamber of the trap is preferred as a means of communication since it provides a ready basin for fluid supply.

The numeral 62 designates a boiler feed injector, the impelling nozzle 63 of which is,in communication with the outlet of condenser coil 57 through a conduit 64. The low temperature inlet of this injector is connected to the trap outlet 61.. Conduit 64 and trap outlet 61 have arranged therein valves 65 and 66 which valves, as indicated, are controlled by the level in boiler 52. The connection 59 between the outlet of trap 60 and evaporator coil 58 includes a cooler 67 at present illustrated as a coil surrounding outlet 61 whereby the liquid passing through coil 61 is materially reduced in temperature. The outlet of the boiler feed injector 62 is connected through a conduit 68 with boiler 52, conduit 68 containing a check valve 69 opening toward the boiler. A branch 70 of conduit 68 communicates with the inlet of a trap 71 which is located above the level of liquid in evaporator coil 58 and has its outlet in communication with the coil at this level. The trap is constructed to permit the passage of vapor while preventing the passage of liquids and from the lower end of the trap a leak 72 so that liquid collecting in the trap may evaporate to the circulation system after an injecting operation, as hereinafter described.

The operation of a boiler feed' injector of this type depends upon the availability of a high temperature vapor as motive medium expanded oil the saturated liquid, and on a supply ofsub-saturated liquid to condense the motive vapor. In I the type of injector of Fig. 5, both the motive and condensing medium are of the same pressure. After priming, the pressure in the mixing chamber of the injector will be considerably lower than that of the condensing liquid so that the path of flow of this condensing liquid can converge as well as that of the motive mixture,'to transfer the pressure head available into velocity with the maximum eihciency.

In operation of this form of apparatus, vapor passing from the boiler acts through ejector 56 to deliver vapor to condenser coil 57. Liquid from this coil passes through trap 60 to evaporator coil 58 and the vapor boiling oil from this evaporator coil is recompressed and introduced to the condenser 57. When the refrigerant withdrawn from boiler 52 in the form of vapor reduces the level in this boiler to a predetermined point valves 65 and 66 are opened. With opening of valves 65 and 66, liquid passes directly from the condenser coil 57 to the impelling nozzle 63 of injector 62; at the same time cooled liquid refrigerant is delivered through outlet 61 from trap 60 to the low temperature inlet of the injector. This liquid will be delivered throughline 70 totrap 71 until the outlet of this trap is sealed, after which the injector will lift check 69 and deliver the liquid to the boiler 52. Trap '71 merely acts as a receptacle for liquid to insure priming of the injector.

It will be obvious from the foregoing that I am enabled by following the outlined method to render available energyreleased through expansion in the form of vapor of a portion of the saturated liquid to assist in circulation of the refrigerant in the system.

Since this method is capable of considerable variation in adaptation to various types of refrigerant systems, I do not wish to be understood as limiting myself thereto or to the apparatus for carrying out, the method except as hereinafter claimed.

I claim:

1. In operation of an ejector type heat pump comprising means to heat a body of refrigerant liquid, means to condense the vapor thus produced to a saturated liquid, and means to evaporate part of said saturated liquid, the method comprising expanding a portion of the liquid con-. densed and utilizing the energy released by expansion of the liquid to return liquid from the condenser to the heating means.

comprising means to heat a bodyof refrigerant liquid, means to condense the vapor thus produced to a saturated liquid, and means to evaporate part of said saturated liquid, the method comprising expanding vapor oif a portion of the liquid condensed and utilizing the energy released by expansion of the liquid to return liquid from the condenser to the heating means, and utilizing the speed and'pressure of vapor delivered to the condenser to recompress vaporsfrom the evaporating means in the condenser,

'4. In operation of an ejector type heat pump comprising means to heat a 'body of refrigerant liquid, means to condense the vapor thus produced to a saturated liquid, and means to evaporate said saturated liquid, the method comprising expanding vapor oif a portion of the condensed liquid, sub-cooling a portion of the condensed liquid to secure recondensation of said vapor and utilizing the energy released by the expansion of the first-named portion of the liquid to deliver the cooled liquid to said heating means, and utilizing the speed and pressure of vapor delivered to the condenser to recompress vapors from the evaporating meansrin the condenser.

5. Heat pumping apparatus comprisinga condenser, means to deliver a vaporized refrigerant under pressure to said condenser for condensation to a liquid therein, and means to expand at least a portion of the liquid into vapor constructed and arranged to utilize the energy released in expansion of vapor from the liquid to return the refrigerant to the first-named condenser.

6. Heat pumping apparatus comprisig a condenser, means to deliver a vaporized refrigerant under pressure to said condenser for condensation to a liquid therein, an evaporator to which the condenser discharges, and means to expand at least a portion of the liquid constructed and arranged to utilize the energy released in expansion of vapor from the liquid to return the refrigerant to the first-named condenser through said means.

7. In an ejector type heat pump. a boiler, a condenser and an evaporator, series connections between the condenser and evaporator, a vapor connection between the'i boiler and condenser and 1115 an injector operated bylexpansion of vapor from. saturated liquid withdrawn fromthe condenser for withdrawing liquid from the condenser and returning it to said boiler. l

8. In' an ejector type heat pump, a boiler, a condenser and an evaporator, series connections between the condenser and evaporator, a vapor connection between the boiler and condenser including an ejector withdrawing vapor from the evaporator and recompressing it in the condenser, and an injector operated byexpansion of vapor from saturated liquid withdrawn from the condenser for withdrawing liquid from the condenser and returning it to said boiler.

GILBERT WILKES. I

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