US1575817A - Refrigerating system - Google Patents

Description

March 9 1926.

I 1,575,817 w. H. CARRIER REFRIGERATING SYSTEM Filed Feb. 2, 1921 4 Sheets-Sheet 1 March 9 1926. 1,575,817

W. H: CARRIER REFRIGERATING SYSTEM Filed Feb. 2, 1921 4 Sheets-Sheet 2 March 9 1926.

REFRIGERATING SYSTEM 4 r 9/ Fljled Feb 2 1921 Sheets Sheet 5 v nwzmroe- 5 22% a array/vi y;

March '9 1926. I

W. H. CARRIER REFRIGERATING SYSTEM Filed Feb. 2, 1921 4 Sheets-Sheet 4 IIIlIIIIIIIIIIIIIIIIIIIIIIIIIII A TTURA/[KS Patented Mar. 9, 1926.

1,575,817- UNITED STATES PATENT oerce.

WILLIS H. CARRIER, OI

. REFRIGERATING SYSTEM.

Application filed February Q, 1921. Serial No" $1,876.

To all whom. it may concern:

Be it known that I, WILLIS H. CARRIER, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented a new and useful Im )rovement in Refrigerating Systems, of WlllCll the following is a specification.

This invention relates to refrigerating systems of the compression type in which a volatile refrigerant liquid is boiled or evaporated in an evaporator by the heat abstracted from the substance being cooled, and the vapor of the refrigerant is withdrawn from the evaporator and delivered by a compressor at a higher pressure to a condenser in which the vapor is condensed, after which the liquefied refrigerant is returned to the evaporator. The most common systems of this kind are those using ammonia as the volatile working substance, but there are numerous recognized objections to the ammonia systems. Ammonia requires high pressures, necessitating heavy, cumbersome, iron or steel apparatus, large reciprocating or positive compressors, and cumbersome power-operated control devices, and on account of the poisonous nature of the substance, a leak in the system is very dangerous, so that expensive and special precautions and apparatus are necessary to reduce to the minimum the possibility of leaks and the danger therefrom.

One of the objects of the invention is to provide a practical, efficient, and safe refrigerating or cooling system'which is 0011 structed and operates in a novel manner, whereby many of the objections to known systems are obviated and certain desirable results are attained which are not possible with the refrigerating systems heretofore used. Another object is to construct the apparatus so that it can be set or adjusted to reduce the temperature of the substance being cooled to a predetermined desired degree and will operate automatically to prevent a lower temperature of the substance, and thus preclude the possibility of freezing and injury to the apparatus.

Other objects, of the invention are to withdraw the vapor of the refrigerant from the. evaporator and deliver it at the required higher pressure to the condenser by means of a centrifugal or non-positive type of compressor, which will give the pressure necessary for the desired operation of the apparatus but will fail to produce more than the desired maximum pressure, and thus operate automatically to determine the degree of refrigeration; also to employ a centrifugal or non-positive type of compressor which can be driven at a constant speed and produce a constant temperature irrespective of the'volume of the vapor being handled, and whereby the degree of refrigeration can be fixed by the speed at which the compressor is driven; also to regulate the temperature or pressure in-the condenser under the control of the temperature of the liquid or material being cooled; also to regulate the temperature of the compressed vapor delivered from the compressor automatically through the medium of a portion of the refrigerant liquid which is returned to the compressor and is evaporated therein to lower the temperature of the .compressed vapor when this becomes necessary; also to produce an efiicient evaporator of novel construction; and also to improve refrigerating systems in the other respects hereinafter described and set forth in the claims.

In the accompanying drawings Fig. 1 is a diagrammatic elevation of a refrigerating system embodying the invention.

Fig. 2 is an enlarged sectional elevation of the evaporator.

Fig. 3 is a fragmentary sectio al elevation thereof on a still larger scale.-

Fig. 4 is a fragmentary transverse section thereof on line 4--4, Fig. 3.

Fig. 5 is an enlarged sectional elevation of the condenser and the controlling devices therefor.

Fig. 6 is an enlarged sectional plan view thereof on line 6-6, Fig. 5.

Fig. 7 is an enlarged sectional-elevationof the compressor and separator for the 'vapor and compressor sealing liquid.

Fig. 8 is an enlarged sectional plan view of the thermostatic trap or device for controlling the temperature of the compressed va or.

ig. 9 is a similar view showing a thermostatic trap or device of slightly modi *fied construction.

A represents an evaporator in whichthe refrigerant is vaporized or boiled, B a con- NEW YORK, N. Y., ASSIGNOR '10 CARRIER ENGINEERING COR- PORATION. 01 NEW YORK, N. Y.

denser for the vapor, and C a pump or compressor which withdraws the vapor of the refrigerant from the evaporator and delivers it under pressure to the condenser. The liquid or substance to be cooled is circulated through the evaporator in which there is an interchange of heat between this liquid and the liquid refrigerant, which evaporates or boils the refrigerant l1qu1d. The compressor, as usual, maintains an absolute pressure in the evaporator sufliciently lower than in the condenser to cause the evaporation of the volatile refrigerant at a temperature low enough to give the desired temperature reduction of the liquld or substance being cooled. The condensed or liquefied refrigerant is returned from the condenser to the evaporator to be again evaporated. The invention is susceptible of embodiment in apparatus of various different constructions and various different volatile li uids, such as ethyl chloride, methyl chloride, sulphur dioxide or carbon tetrachloride, can be used for the refrigerating medium, the construction of the apparatus and the selection of the refrigerant depending more or less upon the conditions to be met and the ca acity required. In this application one o the possible embodiments of the invention is shown and described. This apparatus is designed more particularly to cool water to a temperature slightly above the freezing point, for example, from 38 F. to 35 F. for use afterwards in dehumidifying air, and water at natural temperatures, such as supplied by the usual city service systems, can be used in the condenser for condensing the vapor. Ethyl chloride is preferably used for the volatile refrigerating medium, because it is nonpoisonous and enables the system to be operated at moderate pressures. The system hereindescribed requires only a difference of about 20 to 25 ounds pressure between the evaporator and the condenser. Ethyl chloride is also inert and permits the use of brass in the apparatus and this is desirable because brass gives a rapid exchange of temperatures and ordinary brass fittings and control devices can be used. This invention is not, however, restricted in. application to systems for the purpose stated and other suitable volatile liquids can be used as the refrigerant. The system can also be used for cooling fluids other than water, and for other cooling purposes, and any suitable fluid can be used for cooling the vapor in the condenser.

The evaporator A shown (see Figs. 2-4), comprises an outer cylinder or casing 20 which is provided at its upper end with a hollow head 21 connected by a series of tubes 22 with a hollow head or chamber 23 loosely or movably arranged in the lower end of the casing. The upper head shown is divided into three chambers and the lower head is divided into two chambers. The water or liquid to be cooled is admitted by a supply pipe 24 to one chamber of the upper head 21, flows downwardly through some of the tubes 22 into one chamber of the lower head, th'ence upwardly through other water tubes into the central chamber of the upper head, down again through other water tubes to the other chamber of the lower head and thence up again to the discharge chamber of the upper head from which the water discharges through a discharge ipe 25. The water flow tubes 22 are surroun ed between the upper and lower hollow heads by tubes 26 which are open at their upper and lower ends and form around each of the water tubes 22 a narrow annular flow space for the refrigerant liquid and vapor. The casing of the evaporator is partially filled to a desired predetermined level with the liquid refrigerant X which thus surrounds the lower portions of the water and refrigerant flow tubes. The water or liquid tobe cooled flowing through the evaporator gives up heat to the refrigerant and causes the latter to evaporate or boil. The refrigerant liquid and vapor boil over or discharge out of the upper ends of the outer tubes 26, producing an active, upward circulation of the liquid and vapor through the outer tubes, which sweeps or washes the bubbles of vapor off of the surfaces of the tubes and keeps the surfaces clean and wet with films of refrigerant liquid. This increases the transmis sion of the heat through the walls of the tubes and the efficiency of the evaporator. The evaporator is preferably .laced at an inclination as shown. One of t e chief purposes in this design of evaporator is to use a relatively small body of liquid and a low liquid level over the tubes. This method of evaporation permits the tubes to be very slightly submerged, and have a very low liquid pressure on them so that the evaporation is rapid. This is one of the chief difiiculties with low pressure systems such as the ethyl chloride and on relatively large evaporating surfaces, it is impossible to use efiiciently the ordinary submerged tubes such as used with ammonia. Every foot of submergence means an increase in vapor pressure of 1" of mercury with corresponding increase of temperature, which, with ethyl chloride, amounts to several degrees, while with ammonia it is very slight.

The vapor is withdrawn from the upper portion of the evaporator through a pipe 27 connecting with the intake of the vapor pump or compressor C which compresses and discharges the vapor through a discharge pipe 28 leading to the upper end of the condenser B.

The condenser B, see Figs. 5 and 6, preferably comprises an outer cylinder or casing provided at its .upper end with a hollow head 31 which is connected by flow tubes 32 with a hollow head 33 loosely or movably arran ed in the lower portion of the casing. The upper and lower hollow heads, as in the case of the evaporator, are preferably divided into chambers so that the cooling water or liquid admitted by a i e 34 to the upper head circulates up and ilown through the tubes and chambers of the heads and is discharged from the last chamber of the upper head through a pipe 35. The condenser is also preferably provided with partitions or bafile plates 36 extending alternately from opposite heads of the condenser lengthwise between the flow tubes so as to cause the vapor which is admitted into the upper portion of the outer casing to flow up an down in the condenser casing around the partitions and thus have. an extended, intimate contact with the flow tubes. The lower end of the condenser cylinder or casing is connected by a return i e 37 to the lower portion of the casing o t e evaporator for returning the condensed or liquefied refrigerant from the condenser to the evaporator. A check valve 38 is shown in this pipe to prevent back flow to the condenser, and the discharge of the refrigerant liquid from the condenser is controlled by a suitable trap 39 which, as shown, consists of a float-operated valve that acts to retain a substantially constant quantity of the liquid refrigerant in the bottom of the condenser casing. This valve need not seat tightly and normally remains partly open. A strainer 40 of fine mesh wire, chamois or other suitable material can enclose the valve 39 if desired to prevent any Water in the condenser from being returned to the evaporator. 41 represents a refrigerant supply pipe connecting with the return pipe 37 and provided with .a suitable hand valve 42. The evaporator can be filled to the desired level with the refrigerant through this supply pipe.

The compressor (1 is of a centrifugal or non-positive type. A hydro-turbine comressor of known construction is shown, see ig. 7, comprising an elliptical casing in which revolves a rotor 45 rovided with a plurality of projecting bla es 46. A sealing liquid revolves with the rotor but follows the elliptical casing, due to centrifugal force and twice in each revolution of the rotor the sealing liquid alternately recedes and reenter-s the pockets or spaces between theblades of the rotor. At points at the side of the casing where the sealing liquid is moving outwardly, inlet ports 47 are connected to the vapor inlet pipe 27. Similar outlet ports 48 connected to the discharge pipe 28 are located in the sides of the easing at points where the liquid reenters the rotor. As the sealing liquid recedes from v of the rotor is compressed by the reentering liquid and force out through the outlet 'ports. As the blades of the rotor pass the end of the outlet orts all of the vapor has been expelled and the spaces between the rotor blades are full of the sealing 1i uid ready to repeat the operation. The sea ing liquid used for the com ressor depends upon the nature of the liquid refrigerant and is preferably selected with a view to minimizing the absorption of the refrigerant. If ethyl chloride is used for the latter, mercur or water can be employed as the sea ing liquid for the compressor, mercury being smaller installations. ulphuric acid and glygerine are other liquids which can be use D represents a separator or device for separating from the vapor discharged by the compressor any sealing liquid which may be discharged with the vapor. This separator may be of any suitable construction. As shown it comprisesa casing provided with a suitable baffle 50 which prevents a direct flow of the vapor through the casing from inlet to outlet. The vapor strikes the bafile which throws the moisture down, causing the sealing liquid to accumulate in the lower portion of the casing while the vapor can pass around the edges of the bafile. A pipe 51 leads from the lower end of the discharge chamber 52 of the separator to a tank or reservoir 53 for the sealing liquid and this tank connects by a supply pipe 54 with the vapor inlet pipe or intake of the compressor. The discharge pipe 51 of the separator is preferably controlled by a float-actuated valve which maintains a liquid seal in the bottom of the separator. 55 represents a pressure relief pipe connecting the upper portion of the tank 53 with the inlet or suction pipe of the compressor. 56 represents a branched pipe leading from the bottom of the separator to the stufiing boxes for the rotor of the compressor for sealing these stuffing boxes or glands.

The difference in pressure in the evaporator and in the condenser depends upon the speed of rotation of the compressor greferable for the that is used as the and the centrifugal. force produced since the compressor described cannot give more than a definite known vacuum at a given speed or rotation. A greater vacuum would break the liquid seal in the compressor. Therefore, the pressures in the evaporator and condenser can be fixed as desired within the limits of the compressor by driving the compressor at the appropriate speed and-the danger incident to a lower vacuum in the evaporator is avoided.

.- between the vapor inlet and outlet ports,

such that the rotor of the compressor can draw the liquid from the condenser into the compressor. The admission of this liquid to the compressor is controlled automatically by a trap or device E which,'as'show n in Fig. 8, comprises a valve 61 which is movable in a valve casing 62 interposed in the return pipe 6060 \Vhen this valve is opened the liquid can pass the same and enter the compressor and when the valve is closed it will stop the admission'of the liquid. The valve is opened by a thermoexpansive element 63 preferably consisting "of an expansible chamber containing a volatile liquid, the vapor pressure of which changes with fluctuations in the temperature affecting the element. This thermoresponsive element is located in the separator casing D so as to respond to changes in temperature therein. If the temperature increases above the desired maximum, preferably about 105 F., the thermoresponsive element will expand and open the valve 61 permitting some of the refrigerant liquid to enter the compressor. The liquid will be vaporized by the heat in the compressor andthis evaporation will cause a reduction in the temperature of the vapor in the compressor and separator. The thermostatic-trap E thus acts to maintain a substantially constant, uniform temperature of the compressed vapor. In addition to regulating the temperature of the compressed vapor this trap also serves to return to the compressor any water or sealing liquid which is carried with the vapor to the condenser, thereby preventing the water from accumulating inthe refrigerant circulating system. p

Instead of using the described thermostatic trap, the water condensate can be trapped back to the compressor by means of a trap E such as shown'in Fig. 9. In

this trap the valve 61 controls the flow of the refrigerant liquid through the pipe 60 as above explained, but the thermoresponsive element 63 is enclosed in acasing 64 through which the refrigerant liquid passes from the valve chamber on its way to the compressor. WVater or other relatively non-volatile condensate will pass the valve freely, but when any appreciable quantity of volatile liquid passes the valve,

it will evaporate in chamber 64 and lower the temperature, thus closing the valve 61 and re'venting further passage of the volati e liquid. Other suitable means for this purpose could also be used.

The temperature in the condenser B is preferably regulated automatically by controlling the supply of the cooling water to the condenser, and since the vapor pressure in the condenser changes with the temperature, either a temperature or a pressure actuated control device can be utilized. Preferably a thermostat F is used which extends into the up er part of the condenser and controls the fl bw of compressed air through a pipe to the actuating diaphram or motor of a valve G in the water supply pipe 34 of the condenser. If the desired maximum temperature in the condenser, preferably about 90 -F., is exceeded the thermostat operates the valve G to increase the supply of water which reduces the temperature in the condenser. The compressed air is preferably supplied by an air pump 72 which, for the reason hereinafter explained is connected to the pump 73 that circulatesthe liquid to be cooled through the evaporator A, so that the air pump'operates only when the liquid pump is running. Any other suitable means for regulating the temperature and pressure in the condenser could be used.

H represents a thermostat which acts as a safety device to prevent the refrigeration of the liquid being cooled below a predetermined desired minimum temperature, for example, about 35 F. Preferably this ther: mostat is'located in the cooled liquid discharge pipe 25 from the evaporator and controls the flow of compressed air from the air pump 72 through pipes 74 and 75 to the operating diaphragm or motor of a valve I in the water supply pipe 34 of the condenser. This valve is normally held open during the operation of the system by the air pressure from the air pump 72, but if the temperature of the cooled water falls below the minimum for which the thermostat H is set, this thermostat will act to reduce the air pressure and allow the valve I to close and stop the flow of Water to the condenser This causes an increase in pressure of the compressed refrigerant vapor and breaks the liquid seal of the compressor, in this way reducing the vacuum in the evaporator A and preventing further cooling of the cooled liquid.

Means are also shown whereby the thermostat H in the discharge pipe for the cooled liquid is adapted to stop or reduce the speed of the compressor when the thermostat acts as just explained to prevent the temperature in the evaporatorfa'lling below the minimum for which the thermostat is set. 'For this purpose the motor which drives the compressor is provided with a "rheostat or speed controlling device 81 adapted to be actuated by means of an air motor or diaphragm 82 operated by a1 r pressure delivered thereto t rouglh a pipe 82 under the control of the t ermostat H. When the thermostat acts it will stop or slow down the compressor motor. This saves power and also provides an additional safeguard against the lowering of the temperature in the evaporator beyond a desired or safe point.

I claim as my invention 1. In a refrigerating system in which a volatile liquid refrigerant is emplo ed, the

combination of an evaporator in w ich the refrigerant liquid is adapted to va orize, a condenser including means for con ensing the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it to the condenser, said compressor being of a non-positive t pe adapted to produce a greater or less di erence in pressures in the evaporator and condenser depending upon the speed of the compressor, and means responsive to the temperature produced in the evaporator for limiting the pressure difference produced by said compressor.

2. In a refrigerating sytem in which a volatile liquid refrigerant is emplo ed, the combination of an evaporator in w ich the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerant va 1' from the evaporator and delivers it to t e condenser, said compressor being of a non-positive type adapted to produce a greater or less difference in pressures in the evaporator and condenser depending upon the speed of the compressor, and means responsive to the temperature produced in the evaporator for increasing the pressure in the condenser to limit the pressure difference produced by said compressor.

3. In a refrigerating system in which a volatile liquid refrigerant is employed, the combination of an evaporator in which the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it to the condenser, said compressor being of a non-positive type adapted to produce a greater or less difference in pressures in the evaporator and condenser depending upon the speed of the compressor, and means responsive to the temperature produced in the evaporator for increasing the pressure in the condenser and reducing the speed of the compressor to limit the pressure difference produced by the compressor.

4. In a refrigerating system in which a volatile liquid refrigerant is employed, the

force to produce a difference in pressures.

in the evaporator and condenser that is greater or less depending upon the speed of rotation of the compressor, and means responsive to the tem erature produced in the evaporator for limlting the pressure difference produced by said compressor.

5. In a refrigerating system in which a volatile liquid refrigerant is emplo ed, the combination of an evaporator in w ich the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerant va or from the evaporator and delivers it to t e condenser, said compressor operating by centrifugal force to produce a difference in pressures in the evaporator and condenser that is reater or less depending upon the speed 0 rotation of the compressor, and automatic means governed by the temperature produced by the system for increasing the pressure in the condenser to limit the pressure difference produced by said compressor.

6. In a refrigerating system in which a volatile liquid refrigerant is employed, the combination of an evaporator in which the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it to the condenser, said compressor having means for propelling a body of sealing liquid and operating by centrifugal force to produce a difference in pressures in the evaporator and condenser which is dependent upon the speed of rotation of the compressor, and thermally controlled means for returning a regulated quantity of the refrigerant liquid to the compressor for effecting a controlled reduction'in the temperature of the compressed refrigerant vapor.

7 In a refrigerating system in which a volatile liquid refrigerant is employed, the combination of an evaporator in which the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerator vapor from the evaporator and delivers it to the condenser, said compressor having means for propelling a body of sealing liquid and operating by centrifugal force to produce a diflerence between the pressures in the evaporator and in the condenser which is dependent upon the speed of rotation of the compressor, and automatic means for returning a regulated quantit of the refri rant liquid and sealing liquid rom the con enserto the compressor for separating the sealing liquid from the refrigerant and for effecting a controlled reduction in the temperature of the compressed vapor.

8. In a refrigerating system in which a volatile liquid refrigerant is emplo ed, the combination of an eva oratorin W 'ch the refrigerant li uid is a apted to vaporize, a condenser inc uding means for condens ng the refrigerant vapor, a compressor whic withdraws the refrigerant va or from the evaporator and delivers it to t e condenser, said compressor having means for propelling a body of sealing liquid and operatmg by centrifugal force to produce a difference in pressures in the evaporator and condenser which is dependent upon the speed of rotation of the compressor, and means controlled by the temperature of the compressed refrigerant vapor 'for returning a regulated quantity of refrigerant liquid to the compressor for maintaining a substantially constant temperature of the compressed refrigerant vapor.

9. In a refrigerating system in which a volatile liquid refrigerant is employed, the combination of an evaporator in which the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it to the condenser, said compressor being of a non-positive type adapted to produce a greater or less differ ence in pressure in the evaporator and condenser depending upon the speed of the compressor, means for maintaining a substantially constant temperature and vpressure in the condenser, and automatic means responsive to the temperature produced in the evaporator for limiting the pressure difierence produced by said compressor.

10. In' a refrigerating system in which a volatile liquid refrigerant is empl ed, the combination of an eva orator in w 'ch the refrigerant li uid is a apted to vaporize, a condenser inc uding means for condensin the refrigerant vapor, a compressor whic withdraws the refrigerant vapor from the evaporator and delivers it to the condenser, said compressor being of a non-positive type adapted to produce a greater or less difference in pressures in the evaporator and condenser depending upon the speed of the compressor, automatic means responsive to temperature and pressure changes in the condenser for maintaining a substantially constant temperature and pressure in the condenser, and automatic means responsive to the temperature produced in the evaporator for limiting the pressure difference produced by said compressor.

11. In a refrigerating system in which a volatile liquid refrigerant is employed, the combination of an evaporator in which the refrigerant liquid is adapted to vaporize, a condenser including means for condensing the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it to the condenser, said compressor being of a non-positive type adapted to produce a greater or less differ-- ence between the pressures in the evaporator and in the condenser depending upon the speed of the compressor, means for driving said compressor at a substantially constant speed, and means responsive to temperature produced in the system operating to limit the pressure difference produced by said compressor.

WILLIS H. CARRIER.

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