US3788092A

US3788092A - Thermodynamic cycles

Info

Publication number: US3788092A
Application number: US00270568A
Authority: US
Inventors: D Miller
Original assignee: Statham Instrument Inc
Current assignee: Statham Instrument Inc
Priority date: 1970-09-25
Filing date: 1972-07-18
Publication date: 1974-01-29
Anticipated expiration: 1991-01-29

Abstract

This invention relates to thermodynamic cycles operating between two levels of subatmospheric temperature, whereby power is generated and/or refrigeration obtained, in which a heat transfer liquid is employed having a relatively high vapor pressure at atmospheric temperature.

Description

O United States Patent 11 1 1111 3,788,092

Miller *Jan. 29, 1974 THERMODYNAMIC CYCLES [58] Field of Search 62/87, 116, 117, 118, 175, [75] Inventor: David T. Miller, Port Hueneme, 62/332, 4, 98, 501, 484; 60/26 Calif. [56] References Cited [73] Ass1gnee: gtzlgam Instruments, Inc., Oxnard, I UNn-ED STATES PATENTS 2,009,372 7/1935 Moore 62/118 X Notice: The portion of the term of this 2,175,267 10/1939 Kileffer 62/87 patent subsequent to Sept, 26, 3,693,370 9/1972 Miller 62/332 1989, has been disclaimed. w 0 Primary Examinerilliam F. Dez [22] F'led: July 1972 Assistant ExaminerPeter D. Ferguson 21 App]. N6; 270,568 ST AB RACT Related U.S. Application Data 7 l 63] continuatio an of s N 75 337 S t 25 T1118 1nvent1on relates to thermodynamic cycles opern-m-p er. 0s. ep 1970 Pat No- 3769337O, and Ser. No- 166,316, atmg between two le /els of subatmosphenc tempera Au ture, whereby power 1s generated and/or refrlgeratlon obtained, 1n WhlCh a heat transfer 11qu1d 1s employed 52 us. c1 62/175, 60/26, 62/332, having a relatively high Pressure atmspheric temperature.

[51] Int. Cl. F25b 25/00 10 Claims, 20 Drawing Figures PATENTEU JAN 2 9 I974 SHEET 1 OF 7 PATENTEDJAH 29 1974 SHEET 8 UP 7 THERMODYNAMIC CYCLES This Application is a Continuation in part of my application Ser. No. 75,337, filed Sept. 25, 1970, now US. Pat, No. 3,693,370; and Ser. No. 166,316, filed Aug. 12,1971.

BACKGROUND OF THE INVENTION In the conventional Rankine cycle, the system operates at superatmospheric temperatures. In such cycles, the high temperature stage, sometimes referred to as the boiler is maintained by the expenditure of energy either chemical or nuclear in form. This energy source forms the consumable energy portion of the cycle. The necessary rejection of heat to the atmosphere involved in the very nature of the conventional Rankine cycle contributes to its relatively low thermal and economic efficiency. Additionally, the relatively high temperature base of the cycle, in addition to its low efficiency requires a large capital expenditure per horsepower of usable energy.

SUMMARY OF MY INVENTION In the preferred embodiment of my invention, I employ, as a means of vaporizing the operating liquid, a heat transfer system employing the ambient atmosphere as the heat source to cause vaporization in an evaporator of a liquid whose boiling point is substantially below ambient temperature. The vapor passes to a condenser operating at substantially low subatmospheric temperature due to presence of a heat sink wherein the vapor is condensed.

In such systems, the rate of heat transfer from the ambient atmosphere in the evaporator to the condenser depends on the rate of evaporation of the refrigerant liquid in the evaporator. I have found that the rate of heat transfer is increased to a surprising extent by increasing the rate of movement of the ambient atmosphere at the evaporator while controlling the circulation of the liquid refrigerant from the condenser to the evaporator.

The condensate is pumped from the relatively low pressure condensation zone into the vaporization zone which is at substantially higher pressure than the condensation zone. The power employed in transferring the condensate to the vaporization zone and in moving the ambient atmosphere is derived from the high pressure vapor source of the evaporator. Such means may be an injector which passes condensate into the evaporator. I prefer, however, to use a pump in which the motive power is derived from the relatively high pressure vapor generated in the evaporator; the exhaust vapor from the pump is introduced into the condenser in a closed cycle without any exhaust to the atmosphere. The circulation of the atmosphere is obtained by a fan which is driven by a motor operated by means of the high pressure vapor derived from the same source as the vapor which drives the pump.

The system of my invention also includes apparatus, whereby it may automatically shut down when the condenser temperature rises to a predetermined upper level and also places itself in condition to automatically start operation when the condenser temperature has fallen to a predetermined level. The system also has means for automatically restarting after the system has shut down by reason of a stop in the circulation of liquid whenever the circulation of the liquid is reestablished.

l have provided a pump and also a pump mounting which assures that the pump will begin liquid circulation when the condenser temperature reaches an operating point.

For this purpose, the pump is designed to have a submerged intake and be self-priming.

The fan motor and coupling are designed to operate at the vapor energy levels available and also provide for the required air-to-liquid heat transfer at the evaporator.

The evaporator design is correlated to the air movement and to the required rate of liquid evaporation to obtain the desired rate of heat transfer from the ambient space to the condenser.

The controls are designed for the above purpose to insure the automatic startup and automatic shutdown at the desired temperature level.

The system of my invention may be a source of refrigeration. The evaporator abstracts heat from the ambient atmosphere and thus causes refrigeration in the surrounding atmospheric space.

Alternatively, or in addition, I may employ a portion of the high pressure vapor source from the evaporator to operate an engine for the generation of power in addition to that employed at the circulation of the liquid and air; and the exhaust from the engine may also be introduced into the condenser in a closed cycle.

It will be seen that the energy expended in this cycle, which has economic value is only that consumed in the condensation stage of the cycle since the energy absorbed in the evaporation stage is derived from the ambient atmosphere. The economic cost of the power depends on the economic cost of the cooling medium and where the cooling medium is of negligible cost, the power generator has a cost based on operating cost which may be substantially zero.

The heat abstracted from the atmosphere in the evaporator stage is returned to the heat sink medium in the condensation stage, both of which operate at temperatures below the temperature of the heat source which is the atmosphere. This is distinguished from the conventional Rankine cycle in which low efficiency is largely dependent upon the loss of heat to the atmosphere in the high temperature stage and the prime movers and also in the low temperature stage, all of which are at a temperature above the atmospheric heat sink. For this reason, I have denominated my unique cycle as Inverted Rankine Cycle to distinguish it from the conventional Rankine cycle.

In my preferred embodiment, I employ the cycle as a refrigerating means and employ as a primary refrigerant in the condenser a solid which has a boiling point or sublimation point at atmospheric pressure which will give the desired low temperature, such as, for example, liquefied oxygen, liquefied nitrogen, liquefied hydrogen, or liquefied inert gases, such as liquefied argon and helium. I prefer, however, to use solid carbon dioxide which at 760 millimeters pressure has a sublimation temperature of 78 Centigrade.

The liquid medium employed as the secondary refrigerant, i.e., the heat transfer medium should, therefore, have a boiling point substantially above the temperature of the primary refrigerant, for example, solid carbon dioxide. The secondary refrigerant should have a boiling point substantially below the ambient temperature. In the case of refrigeration, this is preferably below about 45 Centigrade in the case of food storage. For example, I may use Freon-I2, which is a material sold by Du Pont De Nemours C0., and said to be dichloro-difluoromethane having a boiling point at 760 millimeters pressure of 29 Centigrade.

I prefer, however, to employ a refrigerant identified as R-502 constituting an azeotropic mixture composed of 48.8 percent by weight of Freon-22 (CHCIF and 51.2 percent by weight of Freon-I15 (CCIF CF having a vapor pressure at 70 F. of 136.6 psig and at 30 F. of 65.4 psig and O psig at 50 F.

It is another object of my invention to provide control systems which have the function of controlling the level of the liquid in the evaporator.

It is another object of my invention to provide means for regulating the vapor flow to the motors sufficient to provide the required feed to the motor for the liquid circulating pump irrespective of the demand by the motor for the blower or other'auxiliary equipment.

It is also an object of my invention to provide means to control the air circulation rate when the temperature in the system rises or falls below a predetermined point.

It is a further object of my invention to provide means to initiate the startup of this system.

It is the further object of my invention to provide a pump which is of such design and is so positioned in the system as to be a further aid in the control of the system.

It is a further object to provide a pump and condenser design whereby the pump is self-priming.

It is a further object of my invention to provide a fan motor and fan assembly which will operate in conjunction with said pump and derive energy from the same source as the pump motor.

As a result of controls which are provided by my system which may but need not all be employed, as will be more fully described below, the system of my invention arranges the use of available excess power in starting the cooling cycle and circulation of the system.

DETAILED DESCRIPTION FIG. I is a schematic flow diagram of the thermodynamic cycle of my invention.

FIG. 2 is a schematic showing of one application of my invention to a refrigerator.

FIG. l-A is a modification of FIG. 1.

FIG. 3 is a rear view taken on line 3-3 of FIG. 2, showing my presently preferred organization of the system of my invention.

FIG. 4 is a section taken on line 4-4 of FIG. 3.

FIG. 5 is a section taken on line 5-5 of FIG. 3.

FIG. 6 is a section taken on line 6-6 of FIG. 3.

FIG. 7 is a fragmentary section on line 7-7 of FIG. 5.

FIG. 8 is a section taken on line 8-8 of FIG. 7.

FIG. 9 is a fragmentary perspective view of a detail of FIG. 8.

FIG. 10 is a fragmentary section taken on line l0l0 of FIG. 8.

FIG. I] is a plan view of the pump shown on FIG. 3.

FIG. 12 is a cross section of FIG. 11.

FIG. 13 is a section taken on line 13-13 of FIG. 11.

FIG. 14 is a perspective view of a detail shown on FIG. 12.

FIG. 15 is a section taken through the control valve for the turbine.

FIG. 16 is a fragmentary detail of the assembly shown on FIG. 5 with parts in section.

FIG. 16-A is a section taken on line 16A-16A of FIG. 16.

FIG. 17 is a section taken through the ball float valve 11 shown on FIG. 1.

FIG. 18 is a part schematic taken through the temperature control valve shown on FIG. l-A

While any form of pump may be used as the pump and any form of prime mover may be used which will be operated by the vapor from the evaporator, the motor pump assembly with the evaporator described above is a useful aid in attaining the controls made possible by the system of my invention.

It is a useful feature of my invention to employ a pump and condenser assembly which will be selfpriming by employing a submerged liquid inlet to the pump. While any form of fan motor may be employed which will operate by the vapor from the evaporator, I have designed a fan turbine of simplicity and efficiency so that the power required to drive the fan turbine is of such low order as not to unduly interfere with the functioning of the cooling cycle.

FIG. 1 illustrates, schematically, the principles of my invention. The evaporator l is exposed to ambient temperature in the space 2 surrounding the coil of the evaporator. The liquid contained in the cycle has a boiling point to be vaporized at the ambient temperature at the pressure contained in the tubes 1. The condenser 4 is maintained at a temperature below that in the ambient space 2 by means of a cooling system which will result in the desired low temperature. The vapor condenses at the lower pressure attained in the condensation zone and the condensate liquid is pumped by feed pump 6 into the evaporator 1 against a higher pressure. The pump 6 is operated by a motor 7 which takes its operating vapor from the high pressure vapors derived from 1 as will be described below. The motor 7 may be in the form of a reciprocating engine powered by the vapors generated in the evaporator and from which the exhaust vapors discharge into the condenser 5.

The high pressure vapors may also be used to generate additional power beyond that absorbed by the feed pump motor 7 in keeping the cycle continuously operating. A vapor take-off can be at any suitable position in the high pressure vapor stage and pass to the motor 8 which may be of a positive displacement or turbine kind and the exhaust from motor 8 is introduced into the condenser 5. The motor 8 may be used to circulate the air over the evaporator in the space 2 by means of the fan 3 or drive any power absorbing unit or a generator such as an electrical generator.

One of the useful features of my invention is the controls which define the temperature range of the cycle and will cause an automatic startup or shutdown at predetermined temperature levels in the ambient space whose temperature is to be controlled. These controls include a level control by means of a level control valve 9. It also includes a biased valve 10. An additional feature is the use of a bypass valve 11. I may also use a thermostatic valve 103 (FIG. la, 18).

The flow sheet, FIG. 1, illustrates the cycle. The secondary refrigerant liquid is vaporized by heat transfer from the circulated air, and the vapor is passed under the control of float valve 9 (see also FIG. 16 described below) to the input of the pump motor via line 13 (see FIGS. 11-14 described below). The exhaust 12 from the motor passes into line 14 to be introduced into the condenser 5. Vapor is also passed from the evaporator via line 16 under control of the valve (see FIG. described below). The vapor passes into the turbine 8 (see FIGS. 7-10 described below). The turbine exhaust vapors are discharged through line 17 into line 114.

The liquid circuit consists of the self-priming condensate pump 6 which circulates the condensate through line 18 into the evaporator. The bypass valve 11 (see FIG. 17 described below) shuts off the bypass line 19 when liquid is in 100.

In my preferred embodiment, I apply this system to refrigeration in a closed system where the pressure necessary for the efficient operation of the regrigeration system is obtained entirely from the change in enthalpy between the high and low temperature stages including the energy losses in the motors.

FIG. 2 illustrates the use of my invention as a refrigeration unit in an ambient space in which the circulating air induced by the fan 3 passes over the evaporator tubes 4 and a vaporized secondary refrigerant vapor is condensed in condenser S and returned to the evaporator tubes.

The refrigeration unit illustrated schematically in FIGS. 1 and 2 is shown in greater detail in its preferred embodiment in the remaining figures.

Referring to FIGS. 1 through 6, it will be seen that the unit is composed of the primary refrigerant container 21 closed by a cover 22 vented at 23. The condensate chamber 5 is in the form of a tubular member closed at its ends positioned in the bottom of the primary refrigerant container 21 with part of its surface positioned in the chamber 21 and part protruding below the chamber. The condensate container is inclined toward the pump 6 as is shown for FIGS. 1 and 3.

The exposed parts of the primary refrigerant container and its cover are insulated or jacketed with a vacuum jacket to minimize parasitic heat entry into the primary refrigerant container 21. The exposed portion of the condensate chamber 5 is suitably insulated.

The line 24 connecting the condensate chamber 5 and the pump intake (see FIGS. 1 and 3). is inclined at an obtuse angle to the center line of the condensate container 5 as will be more fully described below. The evaporator is formed by a row of spaced tubes 4 connected at their top and bottom by

manifolds

25 and 26. The tubes carry along their exterior length a thin spiral fin 27. The

manifolds

25 and 26 are connected by a balance tube 28 to which the float valve chamber 9 is connected by tubes 29 an 30. See FIGS. 1, 3, and 16. A horn 30 having four

trapezoidal sides

32 and 33 at their forward end embrace the evaporator tubes and at their rear carry a fan shroud 71. See FIGS. 3-8

PUMP AND CONDENSATE CHAMBER ASSEMBLY While any suitable pump may be employed as pump 6, I prefer to use a pump operated by a positive displacement motor which is capable of reciprocating at low frequencies and which will avoid being hung up at dead center. Such a pump is shown in FIGS. 11-14.

The inlet 24 is provided with a suitable inlet ball check valve 36 contained by a wire case 37. The outlet 18 is provided with a suitable ball check valve 38 retained by a seat 39 carrying radial grooves 40. The

pump piston 41 and the pump cylinder 42 are connected to the power piston 43 and the motor cylinder 44 respectively. The pistons are each provided with suitable spring loaded plastic lip seals 34.

The power piston 43 is screw connected at 44' to the valve stem 45. The hollow valve barrel 46 is slidably positioned in the valve cylinder 47 and carries an elongated annular groove 48 and a pair of circumambient detent grooves 49 and 50 cooperating with a springloaded ball detent 51. The valve barrel is slotted with

slots

52 and 53. The internal bore of the valve barrel is grooved with an annular groove 153 and the valve stem 45 passes through a bushing 53' supported on a spider 54 retained by snap ring 54'. The end of the valve stem 45a is supported on a spider 55 which as shown in FIG. 12 bears against the shoulder 56 of the groove 153 and is connected to the stem 45. A spring 57 is positioned in the groove 153 one end against spider 54 and the opposite end against spider 55.

The valve assembly and the pump cylinder assembly are made in two parts screw-connected by suitable assembly screws 57' and suitable seals to the joint.

The valve cylinder carries a detent retainer bore 58 closed by a plug 59. The valve cylinder 47 and the motor cylinder 44 are interconnected by crossover connections 60 which terminate at the outboard end by bore 62 and at the inboard end by bore 61, both closed by suitable plugs.

The valve barrel 47 is closed by a cap 63 which carries a stop spring 64 in the form of a thin flexible washer against which the valve barrel abuts at the end of the inboard movement of the valve barrel. Between the ends of the valve cylinder 47 and the cylinder 44 is positioned a flexible stop washer 65 to act as a flexible abutment at the end of the outboard movement of the valve barrel. I

THE OPERATION OF THE PUMP In the position shown in FIG. 12, the power piston has completed its outboard movement to complete the discharge operation of the pump and the valve barrel has moved into position to start the inboard stroke of the power piston 43. In this position, the crossover of 62, 60, and 61 is connected to the grooved annulus 48 and to the input line 13. The cylinder 44 is connected via 54 and 55, 53 and 52. to the exhaust line 12. The piston 43 starts its inboard movement. The valve rod 45 slides through the bushings 53' and in spider 54 and the bushing in spider 55 until the piston 43 contacts the end of the bushing 53 and then the bushing 53' and spider 54 start their inboard movement compressing the springs 57 until a sufficient tractive effort has been developed to overcome the spring loading of the detent ball 51. In such case, the valve barrel 46 snaps to the left until the detent ball 51 enters the groove 50. During this operation and prior to the snapping of the barrel, vapors have exhausted from the cylinder 44 through the spiders S4 and 55 and the

slots

53 and 52 and the groove 50 into the exhaust 12.

When the valve barrel has snapped to the left, the groove 48 comes into registry with the outlet 12 while still maintaining register with the crossover at 61. The movement of the valve barrel to the left has carried the end of the valve barrel beyond the high pressure inlet 13, thus connecting 13 with the interior of the cylinder 44.

The power piston 43 is now in condition to start its outboard movement towards the position shown in FIG. 12. The high pressure fluid entering through 13 now is in communication with the interior of the cylinder 44 and the piston starts its outboard movement. In so doing, the valve stem 45 which terminates in a head 45-A moves toengage the head 45-A against the spider 55. It then moves to the right with the valve stem and piston to compress the spring 57 until the compression force is sufficient to overcome the loaded detent 51. The continued movement of the piston will draw the valve barrel 46 to the right until the detent ball 51 enters the groove 49. This completes the cycle of reciprocation and the pump is in the position shown in FIG. 12. The consequent operation of the pump will be described below.

If because of the presence of foreign substances, the valve barrel may stick so that the spring 57 may develop insufficient force to move the barrel and pull it away from the detent ball 51; in such case, the piston 43 will continue to move until the spiders compress the spring to bottom the bushings in which case a solid connection is made between the piston 43 and the valve barrel, forcing the valve barrel to move in a desired direction.

The permissible stroke of the piston without inducing a move of the barrel may be controlled by adjusting the length of the rod 45, thus controlling the stroke of the piston.

THE LIQUID CYCLE Referring to FIGS. 1, 3, and 12, it will be seen that the inlet 24 to the pump cylinder 42 is below the level of the lowest point in the condensate chamber 5. In this position with pressure in the pump cylinder ahead of the pump piston 41 ball 36 is seated to close the passageway from 24 to the discharge passageway 18. The ball 38 in this position is seated on the seat 66, FIG. 14, but free communication is established through the port 69 via the grooves 40 to the conduit 18. Assuming no further movement of the piston, the pressure in the conduit 24 will eventually equalize with the pressure in port 69 via the bleed orifice 67. In this condition, the ball 36 will fall away from the seat 68; and free communication will be established from 24 to 18. This will be described further below.

Assuming, however, the continued inboard motion of the piston 43, piston 41 moves in the intake stroke, the ball 36 falls away from the seat 68 into the case 37. Liquid from the condenser passes through 24 into the cylinder 42 to fill the cylinder ahead of the piston. In the outboard stroke of the piston 43, that is, the discharge stroke of the piston 41, pressure is generated in the cylinder 42 ahead of the piston 41, seating the ball 36 on its seat 68 and discharging fluid via the grooves 40 into the discharge conduit 18.

FAN AND FAN MOTOR The fan 70 is mounted for rotation in the shroud 71, mounted at the end of the horn 31. The fan is mounted on a hollow hub 71' in which is mounted'magnet 72 connected to the hub 71 for rotation on the shaft 73 fixed in the journal 74. The turbine 8 is composed of a turbine casing 75 covered by a cover 76 to form a turbine housing 77. The turbine wheel 78 is mounted on shaft 79 for rotation in bearings as shown. Mounted on shaft 79 is a pair of magnets 80 positioned, in the enclosed magnet coupling housing 81. The journal 74 is fixed in the housing 81.

The turbine wheel at its outer periphery carries the impulse blades 82 which extend radially from the pcrimeter of the wheel for a fraction of the radius of the wheel, for example, 10 percent of the radius. The blades 82 are attached and preferably integrally formed with the wheel 78. The wheel and blades may be formed ofa synthetic material, such as a resin, by injection molding but may be made of metal with the individual blades either formed integrally with the metal or rigidly connected thereto as by welding. I prefer, however, to form the wheel and blades by die casting metal.

Referring to FIG. 7, it would seem that the injection nozzle 81 is fed by line 82 from the valve 10 (see FIGS. 1, 3, and 15 to be described below) and the discharge 17 from the casing 77 is connected at the lower end of the turbine cover.

The magnetic coupling is composed of magnets 72 and 80, each formed of two magnets spaced at 90 to each other, two in the housing 81 and two in the hub 71 positioned at right angles to each other. It will thus be seen that the interior of the housing 77 and the hollow magnetic coupling chamber 81 are sealed from the interior of the horn 31 by the enclosure 81. The rotation of the fan is occasioned by the magnetic coupling between the magnets 72 and 80.

THE CONTROL VALVES The control valve 10 (see FIGS. 1 and 15) maintains a predetermined pressure differential across the turbine between input 16 and outlet 17. It is composed of a valve casing 83 in which is positioned a slidable hollow valve member 84 which is closed and beveled at one end 85 and champfered at the other end at 86. Valve member 84 is bored at 85' to contain a spring 86' which at one end bears against the end 87 of the hollow valve member and the spring at the other end is positioned in the seat in the bore 88 of the valve seat 89. Line 90 is connected to the bore 88; and at the other end, the input 16, the line 82 is connected to the turbine inlet. (See FIGS. 1 and 15).

The float valve 9 is shown at FIGS. 1 and 16 and is composed of the float chamber 91 which in connected at the upper and lower end of the float chamber by

crossover conduits

29 and 30 to the liquid equalizing tube 28. (See FIGS. 1 and 16). The chamber 91 is closed at its lower end by the closure 92 bored at 93 to receive a guide stem 94 connected to the float 95 in the chamber 91. The other end of chamber 91 is closed by a cover 95 bored at 96 to receive the conduit 13 and the top of the float 95 carries a cubic valve stem 97 having a conical end 98 to form a needle valve cooperating with the ported seat 99.

The ball float valve 11 is shown in FIGS. 1 and 17. It consists ofa hollow chanber 100 carrying at its upper end a seat 101 to which the outlet pipe 19 is connected and at its lower end is connected by pipe 102 to line 18. Loosely positioned in the chamber 100 is a ball 103 which when seated against seat 101 closes communication between 102 and 19.

The valve shown in FIG. l-A is shown in FIG. 18 and is formed of a diaphragm chamber 103 carrying a diaphragm 104, and the line 110 is connected to the diaphragm chamber 103 above the diaphragm 104. The diaphragm 104 is connected to a stem 105 which is connected to a ball valve member 106 and passes through the sealing bellows 107 and the valve stem and valve ball are biased by

springs

108 and 109. Line 16 is connected above the ball valve member 106 and line 111 is connected to the intake port marked 16 on FIG. when this valve is employed. Line 110 is connected to a conventional thermostatic bulb which generates a pressure respective to the temperature to which it is exposed.

OPERATION OF THE SYSTEM Assuming that the system has been filled with a suitable quantity of the secondary refrigerant liquid in amounts sufficient to cover the inlet 24 to the pump and fill the line 18 to the evaporator and to fill the chamber in the valve 11 to seat the ball float valve 103 to close off communication to line 19, the liquid being also to establish a level in the evaporator sufficient to close the float valve 9. It is to be noted however, that on the initial fill the distribution of liquid may not be as described above but the volume of liquid introduced is designed to be equivalent to such volume. In any case, on the fill where the system does not contain the primary refrigerant, the pressure is equalized in the system. In the case of the azeotrope previously referred to, and assuming a temperature of 70 F. this pressure will be 136.6 psig. It will be observed that since the pressure lines 90 and 16 (FIG. 1) are equalized, the spring bias will cause the valve 10 to be closed with the valve member 84 seated on the seat 85. The fan turbine and fan are inoperative under these conditions, as is the pump.

If dry ice is used, for example, if it is introduced into the condenser chamber 21, the temperature in the condensate chamber 5 will drop, for example, to 50 F. and the consequent pressure in the condensate chamber 5 will be 0 psig. Assuming as above a temperature of 70 F. at the evaporator and O psig in the condensate chamber 5, this pressure differential exerted between 90 and line 16 is sufficient to overcome the spring bias of the spring in valve 10. The valve member 84 moves to open communication between 16 and 82 and the fan motor starts operating. The vapor at high pressure discharges through the nozzle 114 (See FIG. 7) into the chamber 77 of the impulse turbine and discharges through 17 and 14 into the condensate chamber 5. The chamber 77 is sealed from the ambient space as described above by the cover 76 and the fan is driven by the magnetic coupling described above.

As the fan circulates air over the evaporator tubes 4 if the level of liquid in the evaporator had been above the level required to close the float valve 9, the pump is inoperative; however, continued evaporation of the liquid in the evaporator aided by the circulation of air by the fan will eventually drop the level in the evaporator so as to cause the float 95 (See FIG. 16) to drop sufflciently to open the port 99. Vapor enters the line 13 to operate the pump motor and pump as described above.

The arrangement of the pump intake and condensate chamber being as described above, the pump thus being self-priming, it will start immediately to circulate liquid. Valve 11 being closed because of the presence of liquid in the system which is present in valve chamber'100 and liquid having filled the liquid trap 115, the pumped liquid enters the evaporator 26 via 18. This circulation continues with valve 9 controlling the liquid level in the evaporator to shut down the pump by interrupting the vapor flow via 13, if the level rises above the predetermined limit and opening to permit vapor to exit through 13 to operate the pump to replenish liquid in the evaporator, if the level falls below the predetermined limit established by the valve 9.

It will be observed that since valve 10 is a pressure balance valve and the pressure in is fixed by the temperature in the condensate chamber and the spring bias is fixed in the design, the opening and closing of the valve 10 depends on the pressure in line 16. This pressure is a function of the temperature in the evaporator.

If the temperature at the evaporator rises, the rate of vapor generation increases and the pressure in 16 rises sufficient to overcome the spring bias and with valve 10 will open, the fan circulating air at the increased rate. Vapor will pass to the pump motor as well as to the turbine and into the condensate chamber. The increased rate of flow of vapor at the higher pressure increases the pumping rate and increases the rate of condensate accumulation. The pumping rate having been increased, the liquid circulation rate increases to reestablish the liquid level.

The increased rate of circulation increases the rate of heat transfer from the circulating air, resulting in an increased rate of evaporation, increasing the rate of heat transfer to the primary refrigerant by reason of the latent heat of evaporation. The temperature drops at the evaporator aided to some degree by the sensible heat of the cold condensate which has been circulated to the evaporator. The temperature in the evaporator drops as the temperature of the circulating air goes down.

The temperature and pressure of the evaporator are close functions of the air temperature of the ambient air. If the temperature for some reason falls too low, the pressure in the evaporator falls and the rate of evaporation reduces, reducing the rate of vapor passage to the pump and to the fan motor reducing the rate of liquid and air circulation. The rate of heat transfer from the air to the primary refrigerant via the latent heat of the evaporator reduces and the air temperature rises as does the evaporator temperature.

If the temperature swings are too great and temperature falls too low at the evaporator, the valve 10 will close, interrupting the vapor flow to the fan. With air circulation interrupted, the air heats up and the evaporator temperature follows until vapor pressure in the evaporator rises sufficiently to open valve 10 and restart fan, to re-establish the cycle. The action of valve 10 as regulated by the spring 86 provides in this fashion an automatic thermostatic control of circulating air temperature. Should remote temperature sensing be required as shown in FIG. 1A, an independent temperature control valve 103 is positioned in series with valve 10 in the line 16 and achieves the same purpose. In this configuration the spring 86 of valve 10 would be set to control below the temperature control setting of valve 103.

Under normal starting conditions liquid secondary refrigerant is always present in both the condenser 5 and the evaporator 1. The addition of the primary refrigerant to the condenser chamber 21 reduces the pressure in the condensate collector 5 by condensation of the secondary refrigerant vapor contained therein and creates a pressure differential between the evaporator 1 and condenser 5 sufficient to power the liquid pump 6 and the fan 3 (FIG. 1). Normal cooling effect is thereby initiated.

Should liquid circulation from the pump 6 cease for any reason for an extended period of time while the condensate chamber is still filled with heat sink material, the continued evaporation of the fluid in the evaporator l and line 18 will eventually transfer all the liquid to the condensate chamber 5 as a result of the condensation of the vapor at the low temperature of the condenser. This condition may be realized in a practical application, if the system is tilted beyond normal to such an extent that the liquid pump inlet 24 is uncovered so that liquid cannot be transferred from the condensate chamber 5 to the pump outlet line 18 and the driving pressure differential of the system decays to zero.

Valve 11 has been introduced into the circuit to provide automatic restarting capability from this static inoperative mode.

The condition described above is characterized by loss of all liquid from the evaporator side of the system and lack of pressure differential. Valve 11 reacts to these conditions by allowing the ball 103 to fall from seat 101 under the influence of gravity, liquid being absent from chamber 100, thus providing a vent path for vapor being formed in line 18 back to the condensate chamber 5. Cold condensate may now flow through the open check valves 36 and 38 of pump 6 (FIG. 12) into line 18 because of the hydrostatic head of liquid in the condensate chamber 5. The liquid continues to flow until it fills line 18 up to the trap 115 (FIG. 1) and passes into the chamber of valve 11 until ball 103 is floated into a seating position against 101. Violently boiling liquid is now trapped in the abovementioned zone with the primary vapor bypass l9 closed by the action of ball 103. Back pressure is created in the evaporator system sufflcient to close off the outlet check valve 38 of the pump 6 and to create enough driving pressure to trigger the pump into action and commence the normal operating cycle.

I claim:

1. A refrigeration apparatus adapted to operate between two levels of temperature including an evaporation zone adapted to be exposed to a temperature to be controlled, a condensation zone adapted to operate at a lower temperature than the evaporation zone, a vapor conduit connecting the evaporation zone with the condensation zone, a condensation liquid collecting zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor inlet conduit connecting said last-named motor to said evaporation zone and an exhaust connection from said last-mentioned motor to said condensation zone.

2. In the refrigeration apparatus of claim I a valve means in said first-mentioned vapor conduit to said pump motor, said valve means being responsive to the liquid level in the evaporation zone and adapted to close communication in said vapor conduit to said pump motor when the liquid level in the evaporation zone rises above a predetermined level.

3. In the apparatus of claim 1, a pressure sensitive valve means in the last-named vapor conduit connected to said evaporation zone, said valve means being responsive to the pressure differential between said exhaust from said fan motor and the vapor inlet conduit of said fan motor and adapted to close communication between said evaporation zone and said fan motor when said pressure differential is below a predetermined limit.

4. A refrigeration apparatus adapted to be operated between two levels of temperature including an evaporation zone exposed to a temperature to be controlled, said evaporation zone consisting of a row of tubes connected at their tops and bottoms by manifolds, a condensation zone adapted to operate at a lower temperature than the evaporation zone, said condensation zone including an inclined chamber acting as a condensation liquid collecting zone, a vapor conduit connecting the evaporation zone with the condensation zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a liquid inlet to said pump positioned at an angle to the collecting zone and connected to said condensation liquid collecting zone forming a submerged input port to said pump, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor conduit connecting said last-mentioned motor to said evaporation zone, and an exhaust connection from said lastmentioned motor to said condensation zone.

5. In the refrigeration apparatus of claim 4, a valve means in said first mentioned vapor conduit to said pump motor, said valve means being responsive to the liquid level in the evaporation zone and adapted to close communication in said vapor conduit to said pump motor when the liquid level in the evaporation zone rises above a predetermined level.

6. In the apparatus of claim 4, a pressure sensitive valve means in the last-named vapor conduit connected to said evaporation zone, said valve means being responsive to the pressure differential between said exhaust connection and the'vapor inlet conduit of said fan motor and adapted to close communication between said evaporation zone and said fan motor when said pressure differential is below a predetermined limit.

7. A refrigeration apparatus adapted to operate between two levels of temperature including an evaporation zone adapted to be exposed to a temperature to be controlled by said apparatus, a condensation zone adapted to operate at a lowertemperature than the evaporation zone, a vapor conduit connecting the evaporation zone with the condensation zone, a condensation liquid collecting zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a bypass connection between said liquid conduit and said condensate collecting zone, a float valve means in said bypass line, adapted to close communication between said liquid line and said condensation collecting zone, a liquid trap positioned in said liquid line between said bypass line and said evaporation zone, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor inlet conduit connecting said fan motor to said evaporation zone, and an exhaust connection from said fan motor to said condensation zone.

8. In the refrigeration apparatus of claim 7, a valve means in said first-mentioned vapor conduit, said valve means being responsive to the liquid level in the evaporation zone and adapted to close communication in said vapor conduit to said pump motor when the liquid level in the evaporation zone rises above a predetermined level.

9. In the apparatus of claim 7, a pressure sensitive valve means in the last-named vapor conduit connected to said evaporation zone, said valve means being responsive to the pressure differential between said exhaust connection and the vapor inlet conduit of said fan motor and adapted to close communication between said evaporation zone and said fan motor, when said pressure differential is below a predetermined limit.

10. A refrigeration apparatus adapted to operate between two levels of temperature including an evaporation zone adapted to be exposed to temperature to be controlled by said cycle, said evaporation zone consisting of a row of tubes connected at their tops and hottoms by manifolds, a condensation zone adapted to operate at a lower temperature than the evaporation zone, said condensation zone including a liquid collecting zone, a vapor conduit connecting the evaporation zone with the condensation zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a liquid inlet to said pump and to the collecting zone and forming a submerged input port to said pump, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor conduit connecting said fan motor to said evaporation zone, and an exhaust connection from said lastmentioned motor to said condensation zone.

Claims

2. In the refrigeration apparatus of claim 1 a valve means in said first-mentioned vapor conduit to said pump motor, said valve means being responsive to the liquid level in the evaporation zone and adapted to close communication in said vapor conduit to said pump motor when the liquid level in the evaporation zone rises above a predetermined level.

4. A refrigeration apparatus adapted to be operated between two levels of temperature including an evaporation zone exposed to a temperature to be controlled, said evaporation zone consisting of a row of tubes connected at their tops and bottoms by manifolds, a condensation zone adapted to operate at a lower temperature than the evaporation zone, said condensation zone including an inclined chamber acting as a condensation liquid collecting zone, a vapor conduit connecting the evaporation zone with the condensation zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a liquid inlet to said pump positioned at an angle to the collecting zone and connected to said condensation liquid collecting zone forming a submerged input port to said pump, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor conduit connecting said last-mentioned motor to said evaporation zone, and an exhaust connection from said last-mentioned motor to said condensation zone.

6. In the apparatus of claim 4, a pressure sensitive valve means in the last-named vapor conduit connected to said evaporation zone, said valve means being responsive to the pressure differential between said exhaust connection and the vapor inlet conduit of said fan motor and adapted to close communication between said evaporation zone and said fan motor when said pressure differential is below a predetermined limit.

7. A refrigeration apparatus adapted to operate between two levels of temperature including an evaporation zone adapted to be exposed to a temperature to be controlled by said apparatus, a condensation zone adapted to operate at a lower temperature than the evaporation zone, a vapor conduit connecting the evaporation zone with the condensation zone, a condensation liquid collecting zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a bypass connection between said liquid conduit and said condensate collecting zone, a float valve means in said bypass line, adapted to close communication between said liquid line and said condensation collecting zone, a liquid trap positioned in said liquid line between said bypass line and said evaporation zone, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor inlet conduit connecting said fan motor to said evaporation zone, and an exhaust connection from said fan motor to said condensation zone.

10. A refrigeration apparatus adapted to operate between two levels of temperature including an evaporation zone adapted to be exposed to temperature to be controlled by said cycle, said evaporation zone consisting of a row of tubes connected at their tops and bottoms by manifolds, a condensation zone adapted to operate at a lower temperature than the evaporation zone, said condensation zone including a liquid collecting zone, a vapor conduit connecting the evaporation zone with the condensation zone, a liquid conduit connecting such liquid collecting zone with said evaporation zone, and a pump in said liquid conduit, a liquid inlet to said pump and to the collecting zone and forming a submerged input port to said pump, a pump motor connected to said pump, said pump motor positioned in said vapor conduit, a fan positioned adjacent to said evaporation zone, a fan motor connected to said fan, a vapor conduit connecting said fan motor to said evaporation zone, and an exhaust connection from said last-mentioned motor to said condensation zone.