US3200605A

US3200605A - Refrigeration system including charge checking means

Info

Publication number: US3200605A
Application number: US381612A
Authority: US
Inventors: Herbert M Brody
Original assignee: General Electric Co
Current assignee: TRANE CAC Inc A CORP OF
Priority date: 1964-07-06
Filing date: 1964-07-06
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17

Description

H. M. BRODY 3,200,605

REFRIGERATION SYSTEM INCLUDING CHARGE CHECKING MEANS Filed July 6, 1964 Aug. 17, 1965 INVENTOR. HERBERT M. BRODY W H\s ATTORNEY PIC-5.2

4/ a m \X\\\\\ Herbert M. Brody, Tyler, Tex, assignor to General Elec-e tric Company, a corporation of New York Filed July 6, 1964, Ser. No. 381,612 5 Claims. (Cl. 62129) This is continuation-in-part of application Serial No. 284,155, filed May 29, 1963, now abandoned.

The present invention relates to refrigeration systems and is particularly concerned with a refrigeration system including charge checking or measuring means and designed for quickly and accurately determining whether or not the system contains the proper charge of refrigerant.

It is well known that during normal operation of a refrigeration system basically containing a compressor, a pair of heat exchangers and means for controlling the flow of refrigerant between the heat exchangers, the amounts of refrigerant contained in the various components of the system during normal operation of the United States Patent 0 system will vary, depending, for example, upon ambient temperature and load conditions. Hence the amount of refrigerant in any particular component during normal operation cannot be employed as an accurate measure of the total or optimum refrigerant charge. In fact, the determination of the actual refrigerant charge contained in a refrigeration system has always been a problem particularly in the field servicing thereof. While several methods are presently available to the serviceman, none have been completely acceptable. One method commonly used comprises evacuating the system and recharging the system with a new accurately weighed charge of refrigerant. This is wasteful in that most or all of the refrigerant originally in the system is lost during the evacuation. Another known method for providing a refrigeration system with the proper charge has in eluded a comparison of the system performance with predetermined performance curves and adding or removing refrigerant as required. Thisis a time consuming operation and frequently requires the provision of a plurality of performance curves for various operating conditions.

Furthermore, performance curves have been useful only when there are no charge storage devices, such as receivers, accumulators, or modulators, in the system in which indeterminate amounts of refrigerant may collect under normal operating conditions. It has also been proposed to provide a receiver or accumulator component of a refrigerating system with one or more sight glasses, bleed cocks or the like for measuring the amount of liquid refrigerant in such components during operation of the system on a normal refrigerating cycle. Such arrangements do not measure the total charge and have generally been used in systems including the combination of receivers and float or expansion valves for the sole purpose of being sure that there is suificient refrigerant in the system for proper operation of the valves. In other words, such means have been used only with systems of the type in which the performance is not critically affected by the amount of charge as distinguished from systems including capillary or equivalent fixed flow control means where the charge is critical.

It is a primary object of the present invention to provide a simple means for quickly providing, with a high degree of accuracy, the proper refrigerant charge in a I refrigerating system.

It is another object of the present invention to provide a refrigerating system which can be operated in such a manner that substantially the entire charge contained in the system will collect as a liquid and a high pressure gas in a high pressure or condenser component of the

system

3,29,6d Patented Aug. 17, 1965 ice so designed that the liquid level of refrigerant therein is an accurate indication of whether or not the system has the proper total charge.

Further objects and advantages of the present invention will become apparent from the following description and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In accordance with one aspect of the present invention, there is provided a refrigeration system including a com pressor, a first component for receiving and condensing refrigerant from the compressor, a second component adapted to operate as an evaporator and flow control means for controlling the normal flow of refrigerant from the first component to the second. For the purpose of determining Whether the system contains the optimum charge, means are provided for abnormally or substantially restricting the flow of refrigerant from the condenser so that substantially all of the refrigerant charge will collect as a liquid and a high pressure gas in the first component ahead of the restricting means, that is, in the portion of the system between the compressor and the restricting means. By proper proportioning of the first component volume with respect to the total optimum charge, the liquid level of the collected refrigerantis substantially the same over the normal range of ambient temperatures even though the refrigerant density and weight distribution between liquid and gas will vary. The first component is also provided with a liquid level indicator, such as a sight glass or bleed cock, positioned ahead of the flow restricting means to indicate a liquid-gas interface when the volume of said liquid collected during the charge checking cycle is substantially the optimum charge of refrigerant for the system.

For a better understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a diagrammatic illustration of a simple refrigeration system embodying the present invention;

and

FIGURE 2 is a similar diagrammatic illustration of a reverse cycle refrigeration circuit embodying the present invention.

Referring now to the drawing, the refrigeration system shown in FIGURE 1 comprises a compressor 1, a first or high pressure component including a condenser 2, a capillary flow restricting means Sand a second com ponent including an evaporator 4 connected in closed series flow relationship. The compressor 2 Withdraws vaporized low pressure refrigerant from the evaporator 4 and discharges warm high pressure or compressed refrigerant into the condenser 2 where it is cooled and condensed. Liquid refrigerant is fed from the condenser to the evaporator 4 under the control of a flow control means such as capillary 3. During normal operation of the system, refrigerant is continuously condensing as a liquid in the condenser 2 and the liquid refrigerant fed to the evaporator 4 by the flow control means 3 is continuously evaporating in the evaporator so that liquid refrigerant may be present in either or both of these com ponents during normal operation.

In the event that the system develops a leak during use with resultant loss of refrigerant or for any reason contains an excessive charge, it is necessary to either add or remove refrigerant in order to assure the desired operation of the system. The present invention provides a simple and effective means whereby a serviceman can quickly determine whether the system contains the proper charge of refrigerant so that he can either add or remove refrigerant as required. For this purpose, there is provided means to and collected in the high pressure side of the system closed or substantially closed, operation of the compressor causes substantially all of the system charge to be pumped into the condenser 2 Where it will condense. Under such operating conditions, pressures slightly higher than saturation pressures for the condenser ambient will prevail in the portions of the system between the compressor and valve 6 while lower than normal pressures will exist in the evaporator and adjacent portions of the system. As a result, only a relatively small amount of low pressure gaseousrefrigerant Will remain in the low pressure or evaporator side of the system and practically all of the charge will collect as a liquid and high pressure gas in the high,

pressure side of the system which is properly sized in proportion to the total refrigerant charge so that the level of the liquid surface therein is substantially constant or unchanged over a wide rangeof ambient temperatures.

A liquid level indicator such as a sight glass 7 or a refrigerant bleed cock is provided at the proper level in the condenser 2, as for example, in one of the U turns or return bends 8, to enable the Serviceman to check the liquid level and if necessary correct the charge. The position of the indicator is such that the volume of the portion of the system between the indicator and the valve 6 is substantially equal to the volume of liquid collected When the sys-.

tem contains the proper refrigerant charge. When the indicating means shows that the liquid level is at the desired point either by showing a liquid-gas interface in a sight glass or by the fact that a bleed cock discharges a mixture of gas and liquid refrigerant, the Serviceman knows that the system contains the proper charge. On the other hand, if the liquid level is too low so that only gaseous or a flowing mixture of gaseous and liquid refrigerant appears at the indicator oris too high so that only liquid refrigerant is present at this point, refrigerant is either added to the system through suitable charging valve 9 or removed therefrom through a'bleed valve 10 until the proper charge is obtained.

As the position of the level indicating means such as the sight glass 7 is fixed at some elevation in the high pressure component, more specifically in the condenser, during the manufacture of the system, in accordance with the present invention the high pressure component of the system and particularly the condenser which comprises the major volume of the high pressure component is designed to have a storage volume such that when substantially all of the optimum charge of refrigerant for the system is stored therein during the charge checking cycle, the volume of the liquid phase of the stored refrigerant will be substantially the same over the normal ambient temperature range, that is, over the range of from 50 to 100, F. The storage volume of the high pressure component-of the system required for this purpose is dependent upon the total optimum charge for the system and the known density relationships between the gas and liquid phases of the particular refrigerant and their Variations over the normal range of ambient temperature conditions that is the range of from 50 to 100 F.

For a better understanding of the manner in which the required storage volume is determined, consideration Y should be given the fact that if a quantity of refrigerant .is

stored in a given volume, a portion of the refrigerant is in the gaseous phase and the remaining portion is in the liquid phase and the Weight distribution between the two phases depends upon the densities of the liquid and gaseous phases at any particular temperature. While this relationship exists regardless of the size of storage volume, it is possible to calculate a storage volume in which the liquid volume of the stored refrigerant will remain substantially constant over thenormal ambient temperature range.

As an example of the manner in which the storage volume of the high pressure componentis to be determined,

refrigerant R22 will be used as an example. The liquid and gas densitiesin pounds per'cubicfoot of this refrigerant are given in the following table at the ambient temperatures of 50 and 100 F.-

Ambient; Temperature Liquid 7 Gas If a unit volume is to contain or store a givenweight of refrigerant over the temperature range of from 50 to 100 F. at a constant liquid level or liquid volume, then the following relationship between the gas and liquid densities and volumes at the two temperatures must exist using any of the gas-liquid density relationshipswithin the range of from 50 to'l00 F; For example, using the above liquid and gas density values at 50 F., the folloi ing Equation b in whichX equals-the total volume of the high pressure component andW'isthe weight of the optimum charge can be used to determine the optimum total volume'ofthe high pre'ssurecomponent.

For example, if total weight of optimum charge is 10 pounds, then X=.48 cu. a.

While any departure from the optimum liquid volume of about 25 percent will result in changes in liquid level with changes in the ambient temperatures, as a reasonable tolerance in system design without substantially detracting from the accuracy of the charge measuring, the

optimum charge, the-total storage'volume, and the sight glass or equivalent liquid level indicating means are so fixed that the liquid volume does not vary more than 5% from its volume at 75 F. over a temperature range of 50 F. to 100 F. under charge checking conditions. In other words, for Refrigerant 22 systems when properly charged for optimum performance, the; sight glass or equivalent liquid level indicating means may be positioned so that fromabout 20 to 35 "percent of the total volume of the high pressure component is between the sight glass and the charge checking flow restricting means or valve '6 while the remaining volume is between the compressor should be such that about 20 percent of the refrigerant is stored therein in the liquid form.

In a system containing no low spots in any of the refrigerant conduits or components in which liquid refrigerant may tend to become trapped, it has been found that an accurate measure of the total system charge in a simple system such as that shown in FIGURE 1 can be quickly obtained by completely closing the valve 6 and operating the compressor 1 for a period of time, as for example from 5 to minutes, sufllcient to transfer the refrigerant charge to the condenser 2. However, if the system has low spots, particularly in the high pressure side thereof, in which liquid refrigerant may become trapped during the operation on the charge checking cycle, or is one in which refrigerant cooling of the compressor motor is necessary, it has been found that the valve 6 should not be completely closed. By slightly cracking the valve 6 or by employing a valve including a restricted bleed passage so that there is a continuous relatively small flow of refrigerant during the charge checking cycle, the compressor is cooled by the circulating refrigerant and any liquid refrigerant trapped in the system will be swept into the condenser by the flow of gaseous or vaporized refrigerant being withdrawn from the evaporator 4.

An alternative means for providing a restrictive flow of refrigerant through the system during the charge checking cycle is illustrated in FIGURE 2 of the drawing in connection with a reversible refrigeration system.

The system shown in FIGURE 2 comprises a first or outdoor heat exchanger 11, and a second or indoor heat exchanger 12 for heating or cooling an enclosure, the outdoor heat exchanger 11 ordinarily being somewhat larger, that is having a greater volume, than the indoor heat exchanger 12. Means for withdrawing refrigerant from either one of the two heat exchangers and discharging refrigerant into the other includes a compressor 14 and a reversing valve 15. The reversing valve 15 is designed to reversibly connect the discharge line 16 and the suction line 17 of the compressor to the remaining portions of the circuit so thatthe compressor will withdraw low pressure refrigerant from either the indoor or the outdoor heat exchanger and discharge compressed refrigerant into the other of the two heat exchangers. Thus the outdoor heat exchanger 11 functions as a condenser and the indoor heat exchanger 12 as an evaporator when the system is operated on the cooling cycle while the indoor heat exchanger 12 functions as a condenser and the outdoor heat exchanger 11 as an evaporator when the system is operated on the heating cycle.

For normal control of the flow of refrigerant from one heat exchanger to the other on each cycle and to provide the desired normal pressure differentials between the two, the illustrated circuit includes flow control means comprising a heating cycle capillary 18 and a cooling cycle capillary 19 Each of the capillaries also has associated therewith a bypass line for bypassing that capillary during operation of the system on One or the other of the cycles. More specifically, the heating capillary 18 is 'provided with a bypass line 20 including a check valve 21 which permits flow of refrigerant through the bypass line during operation of the system on the cooling cycle, the capillary 19 then operating as the expansion or flow control means. Similarly a bypass line 22 including a check valve 27 bypasses the refrigerant flow around the capillary 19 on the heating cycle so that the heating capillary 18 then provides the desired normal restriction be- .tween the two heat exchangers during operation of the system on the heating cycle. It will be understood, of

course, that a single capillary may be used to control normal flow in both directions or only one of the two or circulating charge of refrigerant in a system of this type under different operating conditions so that, for example, the system will contain the proper circulating or operating charge for the optimum operation thereof on either the heating or the cooling cycle, the system may also include one or more refrigerant storage or charge modifying means such as a receptacle 23 connected by means of a conduit 24 to the main refrigerant circuit and adapted to withdraw a portion of the refrigerant from the refrigerant flow circuit under certain conditions of operation of the system and to return that refrigerant to the circuit under certain other operating conditions. While storage means such as the receptacle 23 may be connected to the refrigerant flow circuit at any of a number of different points, in the illustrated system, the receptacle 23 is connected to the conduit 25 between the outdoor heat exchanger 11 and the fiow restricting capillary 18. The receptacle 23 is also heat exchanged with the line 26 connecting the reversing valve 15 to the outdoor heat exchanger 11. Thus the receptacle 23 is cooled by low pressure suction gas withdrawn from the outdoor heat exchanger 11 by the compressor during operation of the system on the heating cycle with the result that some refrigerant is withdrawn from the system. When the valve .15 is reversed for operation of the system on the cooling cycle, the conduit 26 conducts hot compressed refrigerant from the compressor 14 to the outdoor heat exchanger 11 so that it warms the receptacle 23 and causes the refrigerant stored therein to be returned to the refrigerant circuit. The withdrawal from or addition to the circuit of refrigerant by the modulator receptacle 23 is influenced not only by the heat exchange thereof with a certain portion of the circuit but also by the particular system pressure and temperature conditions in the portion of the system to which it is connected. Receptacle 23 is merely representative of a number of types of dead end or other storage means for normally varying the effective circulating charge in a system and it is to be understood that the present invention is not limited to any particular arrangement or connection of the receptacle 23 or equivalent means for modifying the effective charge of the refrigerant circuit.

For the purpose of fieldchecking the charge in a reverse cycle refrigerating system of this type, the conduit 25 connected to the outlet from the outdoor heat exchanger 11 is provided with a back seating valve 28 and a capillary fiow restrictor 29 bypassing, or connected in parallel with the port 31 of valve 28. During normal operation of the refrigerating system on either the heating or the cooling cycle, the valve 28 is positioned so that there is unrestricted flow through port 31. When it is desired to check the refrigerant charge in the sysem, the valve member 30 is moved to close the port 31.

With the valve member 39 closing the port 31 of the valve 28, the restriction 29 is introduced into the system at the outlet end of the condenser 11. The compressor 14 is then operated with the valve 15 positioned for operation of the reversible refrigeration circuit on the cooling cycle, that is with the outdoor heat exchanger 11 operating as the condenser and forming part of the high pressure component of the system. Warm high pressure refrigerant from the compressor 14 flows through the valve 15 and the conduit 26 into the condenser 11. This high pressure refrigerant warms the storage receptacle 23 so that any refrigerant stored therein is returned to the refrigerant circuit. The returned refrigerant flows through the flow control means 19 to the evaporator, and is transferred by the compressor to the outdoor heat exchanger or condenser 11. As the flow restriction 29 provides some flow or circulation of refrigerant during this charge measuring period, liquid refrigerant stored in any of the portions of the system other than the lower portion of the condenser is carried through the system and into the condenser 11.

In order to indicate the quantity of liquid collected in the condenser, one of the condenser passes is provided with a sight glass $3 or equivalent means spaced from i the valve 28 a distance such that'the volume of the circuit between the sight glass and the valve 28 equals or indicates the volume of the desired amount of liquid refrigerant in the high pressure component during the charge checking cycle. After operation of the compressor with valve 28 closing port 31 until the system reaches an equilibrium operating condition, the condition at the sight glass 33 will indicate whether or not the system is properly charged. If there is a liquid level, that is a liquidvapor interface, showing at the sight glass, the charge is correct. If a refrigerant flow of gas and liquid is observed in the sight glass, the charge is low and an additional charge should be added to the system through a suitable charging valve until a liquid level is observed. If the sight glass shows only liquid refrigerant, the charge is excessive and some refrigerant should be bled oil through a suitable bleed off valve until a liquid-gas level or interface is observed in the sight glass. While the charge measuring valve and flow restriction have been shown at or adjacent the outlet of the heat exchanger operating as the condenser on the chargemeasu'ringcycle, it will be obvious thatthey may be positioned at various points between the two heat exchangers so long asthe total volume of the high pressure component of the system and the volume of the system between the level indicator and the flow restriction are proper for the optimum refrigerant charge. However, the outlet end of the condenser component is a convenient. point since the sight glass or other liquid level indicator can then easily be properly positioned relative to the flow restrictor during manufacture of the condenser.

As has been previously indicated, if the entire system is level so that no portion thereof tends to collect ortrap liquid refrigerant during the charge measuring cycle and no compressor motor cooling is necessary, the outlet from the condenser can be completely closed as by conipletely closing a valve such as valve 6 in the system shown in FIGURE 1.' However, if there are any portions of the system in which liquid refrigerant may become trapped during the charge measuring cycle, it is desirable that a minimum flow be permitted during the charge measuring cycle so that such liquid'refrigerant will be transferred to the high pressure or condenser side of the system for measurement.

The sizing or flow rate of the charge measuring restriction for restricted flow is not particularly critical provided the refrigerant flow through the system during the charge measuring cycle is substantially less than that obtained under ordinary conditions of normal operation. The restriction or flow rate during the charge measuring cycle should be such that the compressor will operate at a relatively low suction pressure and will pump the low pressure side of the system dry of all liquid. The evaporation of liquid from the evaporator Will be aided by the fact that during this cycle, the evaporator is oversized relative to the small actual flow of refrigerant permitted by the restriction so that it is capable of quickly evaporating any liquid offered to it. Furthermore, since the reduced compressor suction pressure correspondingly reduces the refrigerant density in the low pressure side of the system While the increased head pressure correspondingly increases the refrigerant densities in the high pressure side, the weight of gaseous refrigerant in the evaporator and other low pressure components. of the system is quite small relative to the Weight of the refrigerant in the high pressure or condenser components.

In general, flow rates up to about 10 to 50% of the normal flow rate which occurs in the system under Stand ing Rating Conditions for Cooling may be employed with the understanding that the position of the charge measuring means such as the sight glass will be determined to some extent by the charge checking how rate built into the system. Normal flow rate under Standard Rating Conditions for Cooling as prescribed by the Air Conditioning and Refrigeration Institute is the flow rate under 8 conditions including an air flow not to exceed 37.5 cubic feet per minute per 1000 B.t.u.h. to the indoor heat exchanger or coil with the air entering the indoor heat exchanger or coil having an 80 F. dry bulb temperature and a 67 F. wet bulbtemperature. The outdoor conditions are 95 F. dry bulb temperature and a'75 F. wet bulb temperature. I

As a specific example of the flow, rate of the'charge measuring restriction, very accurate measurements of total charge have been obtained when the flow restriction 29provided a how rate which was about of the normal refrigerant flow rate of the tested system on the normal cooling cycle. With a 15% flow rate, it was found that charges in reverse cycle refrigerating systems which ranged from 6 to 8 pounds could be accurately measured by means of the present invention to Within'one ounce of refrigerant; Sincethis deviation is well Within the range of a charge for optimum operation of such systerns, it will beobvious that acceptable results can also be as the capillary 29 for any given system may also depend upon a number of other factors such as the pressure differentials which the compressor cantolerate without damage to its components. Therefore, unless otherwise modified, the terms substantial or abnormal restriction or substantially or abnormally. restricting as used herein with reference to the operation of valve 6, the restriction 2 or equivalentrestricting means, are intended to refer to a total flow restriction, or zero flow rate,.as well as any fiow restriction suchv that during operation of the system on the charge measuring cycle substantially all of the charge will collect as a liquid and high pressure gas in the hi h pressure side of the system ahead of the flow restriction and all of the remaining portions of the system will. contain only gaseous refrigerant at-iower than normal density. Asmallamount of low pressure refrigerantremains inthe low pressure side of the system and a somewhat larger amount of refrigerant maybe present as ahighdensity gas in the condenser above the static body'of liquid. ,Therefore, the term substantially all with reference to the amount of refrigerant charge collected as a liquid in the condenser is intendedto cover a condition in which the remaining portions-of the system are free of liquid refrigerant and the volume of refrigerant collected as a liquid in the condenser is. representative of or an indication of the proper charge of refrigerant for the system. a

From the above description, it will be seen that there has been provided means for quickly, and accurately determining the propercharge of refrigerant. in a refrigerating system. Charge checking can be done in the field in from 15 to 20 minutes with no wasteful loss of refrigerant nor any needfor any accessories or other equipment other than those normally inthe hands of the serviceman. Previously known methods of charge checking have required an hour or'rnore of service time and many of them have involved a substantial loss or Waste of refrigerant and. the use of both evacuation equipment and charge weighing equipment.

While the invention has been particularly described With specific reference to systems including fixed flow control means such as a capillary tube for controlling the refrigerant flow during normal operation, it will be obvious that the charge measuring concept of the present invention is also applicableto refrigeration systems. including an expansion valve or valves instead of fixed flow control means. V

Additional modifications of this invention will occur to those skilled in the'art and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed, and that itis intended to cover by the appended claims all modifications which are Within the true, spirit and scope of the invention.

aaoaeos What I claim as new and desire to secure by Letters Patent of the United States is:

l. in a refrigeration system including a closed refrigerant circuit comprising a compressor, first component for receiving and condensing high pressure refrigerant from the compressor, a second component operating as an evaporator, and means for normally controlling flow of refrigerant from said first component to said second component; means for operating said system on a charge checking cycle including means for substantially restricting the flow of refrigerant from said first component to said second component so that substantially all of the refrigerant charge in said system will collect in said first component when said compressor is operating, said first component having a total volume during operation of said system on a charge checking cycle over a range of ambient temperatures that it will store substantially the proper charge of refrigerant for said system as relatively constant volumes of liquid and high pressure gas, and fiuid level indicating means spaced from said restricting means a distance such that the volume of said first component between said indicating means and said flow restricting stant volumes of liquid and high pressure gas, and liquid whereby a liquid-gas interface at said indicating means during the charge checking cycle indicates that the system contains substantially the proper charge of refrigerant.

2. In a refrigeration system including a closed refrigerant circuit comprising a compressor, a first component for receiving and condensing high pressure refrigerant from the compressor, a second component operating as an evaporator, and means for normally controlling fiow of refrigerant from said first component to said second component; means for operating said system on a charge checking cycle including means for substantially restricting the flow of refrigerant from said first component to said second component so that substantially all of the refrigerant charge in said system will collect in said first component when said compressor is operating, said first componenthavin'g a storage volume such that during operation of said system on a charge checking cycle within an ambient temperature range of from 50 to 100 F., said first component will store the proper charge of refrigerant for said system as a liquid and high pressure gas with the liquid volume varying Within said range not more than five percent from its volume at 75 B, said first component including liquid level indicating means positioned to indicate when the system contains the proper charge of refrigerant.

3. In a refrigeration system including a closed refrigerant circuit comprising a compressor, a first component for receiving and condensing high pressure refrigerant from the compressor, a second component operating as an evaporator, and means for normally controlling fiow of refrigerant from said first component to said second component; means for operating said system on a charge checking cycle including means for substantially restricting the flow of refrigerant from said first component to said second component so that substantially all of the refrigerant charge in said system will collect in said first component when said compressor is operating, said first component having a storage volume such that during operation of said system on a charge checking cycle at an ambient temperature range of from 50 to 100 F., said first component will store the proper charge of refrigerant for said system as a liquid and high pressure gas in which the liquid volume does not vary more than five percent from its volume at 75 F. over said temperature range,

and liquid level indicating means spaced from said restricting means a distance such that the volume of said first component between said indicating means and said flow restricting means is substantially equal to the volume of said liquid portion at F. whereby a liquid-gas interface at said indicating means during the charge checking cycle indicates that the system contains substantially the proper charge of refrigerant.

A refrigeration system including a closed refrigerant circuit comprising a compressor, a first component for receiving and condensing high pressure refrigerant from the compressor, a second component operating as an evaporator and means for normally controlling the flow of refrigerant from said first component to said second component, said first component having a volume sulficient to store at any ambient temperature of from 50 to F. substantially all of the optimum charge of refrigerant for said system in the form of gaseous and liquid phases of relatively constant volumes when the flow of refrigerant from said first component to said second component is abnormally restricted, means for abnormally restricting the flow of refrigerant from said first component to said second component so that substantially all of the refrigerant charge in said system will collect in said first component when said compressor is operating, said first component including means for indicating when the volume of liquid so collected in said first component comprises the optimum charge for the system.

5. A refrigeration system including a closed refrigerant circuit comprising a compressor, a first component for receiving and condensing high pressure refrigerant from the compressor, a second component operating as an evaporator and means for normally controlling the flow of refrigerant from said first component to said second component during normal cooling operation of said system, said first component having a volume sutlicient to store substantially all of the optimum charge of refrigerant for said system in the form of substantially constant volume of liquid refrigerant over an ambient temperature range of 50 to 100 F. and remainder gaseous refrigerant when the flow of refrigerant from said first component to said second component is abnormally resircted, means for abnormally restricting the flow of refrigerant from said first component to said second component, so that substantially all of the refrigerant charge in said system will collect in said first component when said compressor is operating, and liquid level indicating means in said first component for indicating when the volume. of liquid refrigerant collected in said first component corresponds to the optimum charge, said abnormally restricting means providing a refrigerant flowof from ten to fifty percent of the refrigerant flow during normal cooling operation of said system.

References Cited by the Exiner UNITED STATES PATENTS 1,533,336 4/25 Pownall 62-292. X 1,744,287 1/30 Tibbetts 62-292 2,160,276 5/39 McKee 62509 X 2,448,403 8/48 Turner 62--l25 X 2,759,340 8/56 Beslin 62149 X 3,006,155 10/61 Vanderlee et al 62l49 X 3,093,976 6/63 Walcutt 62-509 X ROBERT A. OLEARY, Primary Examiner.

LLOYD L. KING, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,200,605 August 17, 1965 Herbert M. Brody It is hereby certified that error appears in the above numbered petent requiring correction and that the said Letters Patent should read as corrected below.

Column 9, line 19, for "fluid" read liquid line 23, for "stant volumes of liquid and high pressure gas, and" read means is substantially equal to the volume of said column 10, line 42, for "resircted" read restricted Signed and sealed this 8th day of March 1966.

test:

LNEST w. SWIDER EDWARD J. BRENNER testing Officer Commissioner of Patents

Claims

1. IN A REFRIGERATION SYSTEM INCLUDING A CLOSED REFRIGERANT CIRCUIT COMPRISING A COMPRESSOR, FIRST COMPONENT FOR RECEIVING AND CONDENSING HIGH PRESSURE REFRIGERANT FROM THE COMPRESSOR, A SECOND COMPONENT OPERATING AS AN EVAPORATOR, AND MEANS FOR NORMALLY CONTROLLING FLOW OF REFRIGERANT FROM SAID FIRST COMPONENT TO SAID SECOND COMPONENT; MEANS FOR OPERTING SAID SYSTEM ON A CHARGE CHECKING CYCLE INCLUDING MEANS FOR SUBSTANTIALLY RESTRICTING THE FLOW OF REFRIGERANT FROM SAID FIRST COMPONENT TO SAID SECOND COMPONENT SO THAT SUBSTANTIALLY ALL OF THE REFRIGERANT CHARGE IN SAID SYSTEM WILL COLLECT IN SAID FIRST COMPONENT WHEN SAID COMPRESSOR IS OPERATING, SAID FIRST COMPONENT HAVING A TOTAL VOLUME DURING OPERATING OF SAID SYSTEM ON A CHARGE CHECKING CYCLE OVER A RANGE OF AMBIENT TEMPERATURES THAT IT WILL STORE SUBSTANTIALLY THE PROPER CHARGE OF REFRIGERANT FOR SAID SYSTEM AS RELATIVELY CONSTANT VOLUMES OF LIQUID AND HIGH PRESSURE GAS, AND FLUID LEVEL INDICATING MEANS SPACED FROM SAID RESTRICTING MEANS A DISTANCE SUCH THAT THE VOLUME OF SAID FIRST COMPONENT BETWEEN SAID INDICATING MEANS AND SAID FLOW RESTRICTING STANT VOLUMES OF LIQUID AND HIGH PRESSURE GAS, AND LIQUID WHEREBY A LIQUID-GAS INTERFACE AT SAID INDICATING MEANS DURING THE CHARGE CHECKING CYCLE INDICATES THAT THE SYSTEM CONTAINS SUBSTANTIALLY THE PROPER CHARGE OF REFRIGERANT.