US2145692A

US2145692A - Refrigerating method and apparatus

Info

Publication number: US2145692A
Application number: US114739A
Authority: US
Inventors: Jones Walter
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1936-12-08
Filing date: 1936-12-08
Publication date: 1939-01-31
Anticipated expiration: 1956-01-31

Description

Jan. 3l, 1939. w. JONES REFRIGERATING METHOD AND APPARATUS Filed Dec.

es,v 1956 -INVENTOR WALTER L/O/VE ATTORNEY Pafented Jan. 3l, 1939 [STATES t;

amasar REFRIGERATING METHOD Arm v i 'mg Waiter Jones, Princeton, N. l., assigner to Corporation, Newark, N. il., a corporation of Delaware Application December t, i936, Serial No.. litt@ 14 El. (Wl. dfilim This invention relates to refrigeration.

It is generally recognized that centrifugal refrigerating systems using low pressure refrigerants, such as carrene (dichloromethane), are

highly efficient. ant at conventionally low pressure, and return- 5 The general object of the present invention is ing the last-mentioned refrigerant for recirculato provide a method of and means for effecting tion in heat exchange relation with other of said refrigeration in which centrifugal refrlgerating first-mentioned refrigerant. apparatus may be used either alone or in con- Another feature of the invention resides in junction with conventional positive displacement withdrawing refrigerant gas from the evaporator compressing and condensing apparatus to effect of a refrigerating system, routing the refrigerant refrigeration. gas in two parallel paths, condensing refrigerant Another object of the invention is to provide in one of the paths at relatively high temperaa method of and means for augmenting the ture and pressure, condensing refrigerant gas in capacity of existing high pressure refrigerating the other of said paths at relatively low temsystems. perature and pressure, Aand returning to the re- Another object of the invention is to provide frigerant evaporator refrigerant condensed in a method of and means for increasing the capaciboth of said paths. ty of a given refrigerant evaporator, whereby Another feature of the invention resides in increased refrigerating effect may be obtained evaporating a refrigerant gas, condensing a poreconomically, as regards both the initial equiption of the gas at high temperature and high ment cost and operating cost. pressure, condensing another portion of the gas According to the invention, existing refrigeratat low temperature and low pressure, pumping ing systems may be provided with auxiliary cenrefrigerant liquefied in said last-mentioned step trifugal refrigeratlng systems which become a to a different pressure, substantially equal to part thereof and greatly increase the overall rethat at which the high pressure refrigerant is frigerating capacity, without necessitating excondensed, mixing refrigerant condensed in both tensive revision of existing systems and without of these ways and supplying such mixed refrigersetting up complete and expensive independent ant to the evaporator. systems. Another feature ofthe invention resides in A feature of the invention resides in supplying withdrawing refrigerant from an evaporator, refrigerant to an evaporator coil, `withdrawing routing a rst portion of the refrigerant in a first refrigerant from the evaporator coil after it has path, condensing said first portion of refrigerant expanded therein and absorbed heat from the at relatively high pressure and temperature, conmedium surrounding the evaporator coil, passing densing a second portion of said gas at relatively the withdrawn refrigerant in parallel paths, comlow temperature and pressure, withdrawing air pressing and condensing refrigerant passed' and other non-condensable gases from said secthrough one of said paths, and condensing reond portion of the refrigerant, supplying said frigerant passed through another of said paths withdrawn air to the first portion of refrigerant, by passing in heat exchange relation therewith and purging the air therefrom 40 other refrigerant having a temperature several Other objects, features and advantages of the degrees lower than the saturation temperature of invention will be more apparent from the followthe withdrawn refrigerant gas, and returning reing description to be read in connection with the frigerant condensed in both of said paths to said accompanying drawing, which diagrammatically evaporator coil for reevaporation and recircularepresents a refrigerating system in accordance tion through the system. with theinvention.

Another feature of the invention resides in con- Referring now to the drawing, 5 designates a densing at relatively low pressure refrigerant ges series of gas suction lines Areturning from one or which is conventionally condensed at relatively more direct expansion evaporators,-` For purhigh pressure, by circulating in heat exchange poses of illustration, it will be assumed that am- 5o Another feature of the invention resides in condensing at relatively low pressure refrigerant aas which is conventionally condensed at relatively high pressure, by circulating in heat exchange relation therewith other refrigerant, compressing and condensing the other refrigermonla is the refrigerant employed in these evaporators, but it will be understood that the invention contemplates the use of all types of refrigerantswhose evaporation and/or condensation is accomplished either at relatively highv orlow pressure. The ammonia gas returning through lines 5 may at times be accompanied by unevaporated liquid and also by oil. Such mixture passes from 'lines 5 through line 6 into the accumulator 1,

where the liquid refrigerant and/or oil falls to the bottom. Thus, nothing but ammonia'gas is permitted to pass out of the top of the accumu-I lator 1 through line 8, either through line 9 to the positive compression ammonia compressor I 0, or through line II to the low pressure condenser generally designated I2. A refrigerant, such as carrene, serving as a condensing medium, is supplied to the condenser I2 through supply line I3 and withdrawn therefrom through return line I4. The temperature of the carrene within the condenser I2 is maintained at a point a few degrees, for example, 8 to 10, below the saturation temperature of the ammonia gas with which it is passed in heat exchange relation. Thus, the ammonia gas is condensed. Although such apparatus has not been shown, in order to simplify the drawing, it Will be understood that associated with the lines I3 and I4 is suitable apparatus for compressing (preferably centrifugally) and condensing the withdrawn carrene gas and for returning it in liquid form to the condenser I2 Ammonia condensed in condenser I2` passes to receiver .I5 through line I6. Pump I1 withdraws ammonia liquid from receiver I5 through line I8 at low or evaporatingl pressure, .and pumps it through line I9 at high pressure to main liquid supply line 20, which feeds the liquid lines 2| connected to the various 'evaporators of the system. Line I9 is provided with a non-return check valve 22, which permits flow from the pump I1 to the line 20 but prevents flow in a reverse direction.

Ammonia gas compressed by compressor I0 .is

passed through line 23 to high pressure condenser 24, of any desired type, whence relatively hot ammonia liquid drains to receiver 25 through line 26. `It will be noted that main liquid supply line 20 extends into and well below the normal liquid level of receiver 25; it may, if desired, be connected to the bottom of the receiver. Line 20 is provided with a valve 21, lying beyond the junction point of lines I9 and 20, and also with a valve 28 between this junction point and the receiver. Line I9 is provided with a valve 29 between check valve 22 and the junction point of lines I9 and 20.

When condenser I2 is rendered operative, by the circulation of refrigerant supplied thereto through line I3, at the same time that the compressor I0 is operative,

valves

21, 28 and 29 are open. Thus, the.cold ammonia liquid from condenser I2 can flow out through therlines 2|, or can flow down to the high pressure receiver 25.

It is condensing pressure maintained in the condenser 24 which determines the pressure in the liquid feed lines 2I and, consequently, the pressure against which the pump I1 operates. Since valves 21 and 28 are open, no regulation of the capacity of pump I1 is required, since any excess from this pmp will go down into the receiver 25. If the pump should be delivering insufficient liquid, the deficiency is made up by liquid which drains down from the high pressure condenser 24. Thus the receiver 25 acts as a balancing tank. When compressor I0 is rendere-d inoperative and all of the condensation of the system is effected in condenser I2, the valve 28 is closed, while valves 29 and 21 are left open. Under this condition of operation, with 8 POSI- tive liquid pump, such as I1, means must be provided to vary the pump capacity so as to maintain a constant pressure in the liquid delivery lines 2| under variable flow conditions. 'Ihis is done by providing pump relief bypass line 30, provided with spring loaded check valve 3|,1which permits any excess liquid delivered by the pump to be returned to the low pressure receiver I5. Check valve 3| is adapted to open whenever the pressure in line I9 rises above a predetermined point, and hence prevents excessive pressure in line I9.

Obviously, when it is desired to effect condensation in condenser 24 alone, and to render the condenser I2 inoperative, valve 29 is preferably closed while valves 28 and 2I`are open. In suchl case, pump I 1, as well as the apparatus associated with refrigerant lines I3 and I4, will be rendered inoperative.

Any air or other non-condensable gases which I, may get into the ammonia system will gradually accumulate in the 1o w pressure condenser I2 and prevent eicient condensation. Accordingly, a small ammonia compressor 32 is provided, its inlet'being connected by line 33 to the last pass offcon-denser I2, which is the 'point where air would tend to accumulate. Pump 32 will pump the air and uncondensed ammonia gas through lines 34 to line 23, whence it passes intothe high pressure condenser 24. Line 34 is provided with check valve 35 which prevents flow from line 23 to compressor .32. The air delivered to condenser 24, being heavier than the ammonia gas," will finally pass down vthrough line 26 to the receiver 25. whence it may be purged by means of the air purge 36, which may be of any one of many well known types.

Oil is drained from accumulator 1 through Vdrain line 31 provided with a suitable stop cock 38, and refrigerant liquid is drained therefrom through line 39 to line I8 and thus to the intake side of refrigerant liquid pump I1.

To purge the system of air and other noncondensable gases when the condenser I2 alone is operative, (i. e., when compressor I0 and condenser 24 lare inoperative) a. purge device, generally designated 40, is provided. Within the casing 4I is positioned an ammonia expansion coil 42 which receives liquid refrigerant from the line I9 through the line 43, provided with suitable hand valve 44 and expansion valve 45. Refrigerant expanded in the coil 42 is returned to line II through line 46, this refrigerant being recondensed in condenser I2. Air and other non-con- 4densable gases, and also uncondensed ammonia gas, is withdrawn from the line 34 through the line 41 and supplied to the interior of the casing 4I. Preferably, a valve 48 is positioned in line 41 and a valve 49 is positioned in line 34 to control fiow through these lines. When the condenser I2 alone is operative, valve 48 is opened and valve 49 is closed; but when the high pressure and low pressure condensers are both op erative, the valve 49 is opened and the valve 48 is closed. Gases supplie-d to the interior of the casing 4I through line 41 contact the cold evaporating coil 42. Ammonia vapors are condensed and fall to the bottom of casing 4I, whence they are returned through line 50 to line I E, leading to the liquid receiver I5. Air and other non-condensable gases -are relieved from the casing through line 5I, preferably provided with a valve 52 designed to maintain a predetermined pressure within the casing 4I.

Thus, it will be apparent that there has been provided a system in which an auxiliary condensing system may be cut in or cut out, at will, depending upon variations in heat load on the evaporators of the system. When operative, the auxiliary condensing system substantially increases the refrigerating effect produced by the evaporators.

Such an auxiliary condensing system as has been herein described can be quickly and easily installed, and it is to be noted that it in no way impairs the effectiveness or complete utilization of the apparatus in`conjunction with which it is used. As a matter of fact, it substantially increases the operating efficiency of such apparatus, since the refrigerant liquid supplied to the evaporators is at a lower temperature, which results in decreased fiashing of refrigerant and more useful refrigerating work per unit of refrigerant supplied to the evaporators.

When the invention is used in such installations as breweries, or the like, many of which have long been served by ammonia systems, the centrifugal compressor used to compress the low temperature low pressure refrigerant may frequently be fitted into the heat balance of the brewery, as when the compressor is driven by a steam turbine, utilizing steam which would ordinarily be wasted. Under such conditions, the cost of operating applicants system and thus providing for increased refrigerating effect is especially low as compared with the cost of operating other types of apparatus.

While the invention has been described with particular reference to the modification of existing ammonia and similar systems, it will be understood that the construction of new systems embodying the invention is deemed within the purview hereof.

Since many changes may be made in the invention without departing from the scope thereof, it is to be understood that the foregoing description and accompanying drawing are intended as illustrative only, applicant limiting himself only as indicated in the appended claims.

I claim:

l. The method of refrigeration which consists in evaporating a refrigerant to absorb heat from a medium to be cooled, condensing a portion of the refrigerant at relatively high pressure, simultaneously condensing another portion of the refrigerant at relatively low pressure, mixing said portions of condensed refrigerant and re-evap.- orating said mixture.

2. The method of refrigeration which consists in evaporating a volatile refrigerant to absorb heat from a medium to be cooled, compressing one portion of the refrigerant gas, condensing said portion of the refrigerant gas at substantially the pressure to whichsit has been compressed, simultaneously condensing another portion of the refrigerant gas at relatively low pressure, mixing said portion of refrigerant condensed at high pressure and said pressure of refrigerant condensed at low pressure, and re-evaporating the resultant mixture.

3. The method of refrigeration which consists in evaporating a refrigerant to absorb heat from a medium to be cooled, compressing a portion of the Vaporized refregrant, condensing said portion of the refrigerant at a pressure substantially equal to that to which it is compressed, simultaneously condensing anothergportion of the refrigerant at portions of the refrigerant.

4. The method of refrigeration which consists in evaporating a' refrigerant to absorb heat from a medium to be cooled, routing the resultant refrigerant vapor in parallel paths, compressing the refrigerant vapor passed in one of said paths and condensing said compressed refrigerant at substantially the pressure to which it has been compressed, simultaneously condensing refrigerant passed through another of said paths at a pressure substantially lower than that at which refrigerant in said first mentioned path is condensed, increasing the pressure of said refrigerant condensed at low pressure, mixing said refrigerant crndensed at low pressure with said refrigerant condensed at high pressure yand re-evaporating the resultant mixture.

5. The method of refrigeration which consists in evaporating a volatile refrigerant to absorb heat from a medium to be cooled, routing the resultant refrigerant vapor in parallel paths, compressing the refrigerant passed in one of said paths and condensing such refrigerant substantially at the pressure/to which it has been compressed, simultaneously condensing refrigerant routed in another of said parallel paths at a pressure substantially equal to the evaporating pressure,`increasing the pressure of refrigerant condensed in said last-mentioned condensing step substantially to that at which refrigerant is condensed in said first mentioned path, mixing refrigerant 'from said first path and refrigerant from said other path and re-evaporating the resultant mixture.

6. The method of refrigeration which consists in evaporating a refrigerant to absorb heat from a medium to be cooled, compressing a portion of the resultant refrigerant vapor and condensing said portion at relatively high pressure, simultaneously condensing another portion of the resultant refrigerant vapor at a lower pressure by passing in heat exchange therewith a second refrigerant having a temperature lower than the saturation temperature of the refrigerant vapor to be condensed, mixing the refrigerant, condensed at high pressure and the refrigerant condensed at low pressure, and re-evaporating the resultant mixture.

7. The method of refrigeration which consists in evaporating a volatile refrigerant to absorb heat from a medium to be cooled, routing the resultant refrigerant vapor in parallel paths, compressing refrigerant routed in one of said paths and condensing said compressed refrigerant at relatively high pressure, simultaneously condensing refrigerant routed in another of said parallel paths at relatively low pressure, positively v'thdrawing air and other non-condensable gases from said second path at a point beyond that at which low pressure condensation occurs and increasing the pressure of said withdrawn air and other gases, supplying saidA withdrawn air and other non-condensable gases to high pressure refrigerant in said first mentioned path, purging f said air and other non-condensable gases to the atmosphere, mixing refrigerant condensed in each of said paths and re-evaporating the resultant mixture.

8. A method of refrigeration which consists in evaporating a volatile refrigerant to absorb heat from a medium tc be cooled, routing different portions of the resultant vapor in different parallel paths, compressing refrigerant gas routed in one of said paths and condensing said compessed refrigerant at relatively high pressure, si-

.. multaneously condensing refrigerant routedv in another of said paths at relatively low pressure, equalizing the pressures obtaining in the downstream portions of said paths, mixing the refrigerant condensed in each of said paths and reevaporating the resultant mixture.

9. In a refrigerating system, an evaporator, a gas suction line leading from said evaporator, a

Arefrigerant compressor, a first refrigerant condenser, means for supplying gas from said suction line to said compressor, and thence to said rst condenser, a refrigerant liquid receiver, a conduitl connecting said first condenser with said receiver, a refrigerant liquid supply line leading from said receiver to said evaporator, a second condenser, means for supplying gas from said gas suction line to said second condenser, means for circulating through said second condenser a heat exchange medium for condensing refrigerant gas supplied to said second condenser, means for increasing the pressure of refrigerant condensed in said second condenser to substantially the pressure of refrigerant being discharged from said first condenser, and means connecting the discharge side of said pressure-increasing means and the refrigerant liquid supply line, said pressure-increasing means and said compressor being simultaneously operative.

10. In a refrigerating system, an evaporator, a gas suction line leading from said evaporator, a refrigerant compressor, a first refrigerant condenser, means for supplying gas from said suc tion line to said compressor and thence to said first condenser, a refrigerant liquid receiver, a conduit connecting said first condenser with said receiver, a refrigerant liquid supply line leading from said receiver to said evaporator, a second condenser, means for supplying gas from said gas suction line to said second condenser, means for circulating through said second condenser a heat exchange medium for condensing refrigerant gas supplied to said second condenser, a liquid pump for increasing the pressure of refrigerant condensed in said second condenser to substantially the pressure of refrigerant being discharged from said first condenser, means connecting the discharge side of said liquid pump and the refrigerant liquid supply line and a second refrigerant liquid receiver connected to the refrigerant liquid discharge side of said second condenser and connected to the intake side of said liquid pump, said liquid pump and said compressor being simultaneously operative.

11. In a refrigerating system, an evaporator, a g'as suction line leading from said evaporator, a refrigerant compressor, a first refrigerant condenser, means for supplying gas from said suction line to said compressor and thence to said first condenser, a refrigerant liquid receiver, a conduit connecting said first condenser with said receiver, a refrigerant liquid supply line leading from said receiver to said evaporator, a second condenser, means for supplying gas from said gas suction line to said second condenser, means for circulating through said second condenser a heat exchange medium for condensing refrigerant gas supplied to said second condenser, a liquid pump for increasing the pressure of refrigerant condensed in said second condenser to substantially the pressure of refrigerant being discharged from said first condenser, said liquid pump and said compressor being simultaneously operative,

' means vconnecting the discharge side of said liquid pump and the refrigerant liquid supply line, a second refrigerant liquid receiver connected to the refrigerant liquid discharge side of said second condenser and connected to the intake side of said liquid pump, a relief bypass line connecting the discharge side of said pump and said secondliquid receiver, and check valve means in said relief bypass line for permitting flow from the discharge side of said pump to said second receiver whenever the fluid pressure at the outlet side of said pump rises above a predetermined point.

12. In a refrigerating system, an evaporator, a gas suction line leading from said evaporator, a refrigerant compressor, a first refrigerant condenser, means for supplying gas from said suction line to said compressor and thence to said first condenser, a refrigerant liquid receiver, a conduit connecting said first condenser with said receiver, a refrigerant liquid supply line leading from said receiver to said evaporator, a second condenser, means for supplying gas from said gas suction line to said second condenser, means for circulating through said second condenser a heat exchange medium for condensing refrigerant gas supplied to said second condenser, a liquid pump for increasing the pressure of refrigerant condensed in said second condenser to substantially the pressure of refrigerant being discharged from said first condenser, said liquid pump and said compressor being simultaneously operative, means connecting the discharge side of said pump and the refrigerant liquid supply line, gas pump means Whose inlet is connected to the discharge side of said second condenser, means for supplying gas pumped by said gas pump means to said first mentioned condenser, and means in combination with said receiver for purging from the system gas pumped by said gas pump means.

13. In a refrigerating system, an evaporator, an accumulator, a gas suction line leading from said evaporator to said accumulator, a refrigerant compressor, a first refrigerant condenser, means for supplying gas from said accumulator to said compressor and thenceto said first con- -ant condenser, means for supplying gas from said accumulator to said second condenser at substantially the pressure prevailing within said accumulator, means for circulating through said second condenser a heat exchange medium for condensing refrigerant gas supplied to said second condenser, means for increasing the pressure of refrigerant condensed in said second condenser to substantially the pressure of refrigerant being discharged from said first condenser, said pressure-increasing means and said compressor being simultaneously operative, and conduit means connecting the discharge side of said pressure-increasing means and the refrigerant liquid supply line.

14. The method of operating a refrigerating system including an evaporator, a compressor and a condenser, which includes the steps of withdrawing refrigerant vapor from said evaporator, routing a portion of said Withdrawn refrigerant in a c ourse bypassing said compressor and condenser, condensing said portion of refrigerant at relatively low pressure While said compressor is operative, increasing the pressure of said portion" of refrigerant after condensation thereof, and returning the same to said evaporator for re-evaporation.

WALTER JONES.