US3012412A

US3012412A - Refrigerator humidity control

Info

Publication number: US3012412A
Application number: US689151A
Authority: US
Inventors: Muffly Glenn
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-10-09
Filing date: 1957-10-09
Publication date: 1961-12-12
Anticipated expiration: 1978-12-12

Description

Dec. 12, 1961 G. MUFFLY 3,012,412

I REFRIGERATOR HUMIDITY CONTROL Filed 001;. 9, 1957 1 INVENTOR. 61 5/1 M 0973 BY E1. 47 65 firm/ 6.

United States Patent 3,012,412 REFRIGERATOR HUMIDITY CONTROL Glenn Muflly, 1541 Crestview Drive, Springfield, Ohio Filed Oct. 9, 1957, Ser. No. 689,151 Claims. (Cl. 62-176) This invention has to do with the control of humidity in confined spaces and particularly in food storage compartments of refrigerators. The present practice of automatically defrosting the cooling surfaces of non-freezing food spaces tends to increase the average humidity in such spaces. This humidity is still higher when the air is cooled by non-frosting surfaces or when doors are opened frequently, particularly in southern or coastal regions where the kitchen air is very high in humidity. Because of weather changes, climate difierences and variations in door openings and other usage there is no fixed formula, such as a constant cooling surface temperature, which will provide uniform humidity, hence it is found desirable to provide means for offsetting these variations.

A main object of this invention is to provide controlled recirculation of a portion of the air over the cooling surfaces to remove additional Water vapor from such air as required to maintain a desired average humidity in the food storage space.

Another object is to vary the rate of air circulation over the cooling surfaces in order to hold its humidity within desired limits.

A further object is to vary the temperature of the cooling surfaces to vary the amount of moisture condensed from the air for the purpose of maintaining the moisture content of the air within desired limits.

An additional object is to select for recirculation a portion of the air which is warmer and/or higher in humidity.

Still another object is to employ a fan or blower both for circulating the air and for separating a portion of lesser density to be recirculated.

A still further object is to provide in a multiple zone refrigerator for selective removal of water vapor from the air supplied to a certain one of said zones.

In the drawings:

FIGURE 1 is a broken sectional view of a refrigerator showing the cooling element, air circulating means and controls. 7

FIGURE 2 is another view of the air circulating and flow modifying means.

FIGURE 3 is a diagrammatic view showing how the same principles may be employed in a multiple zone refrigerator.

Referring to FIG. 1 the centrifugal blower 10, driven by shaft 12 and having vanes 14, is located in casing 16. Cold air taken in at the central port 18 is delivered via duct 20 to the refrigerated space. A portion of the air is diverted by the damper 22 to how through the recirculation duct 24. Due to the centrifugal effect of I tor.

On the other hand any water carried by the air in the form of droplets will by the same centrifugal effect be thrown against the inner wall of casing 16 and enter the trap 26, from which liquid water drains through tube 28 to a suitable disposal means. In this way the air which flows through the duct 20 is the drier and colder portion.

3,012,412 Patented Dec. 12, 19 61 ice The diverted air flowing through duct 24 passes again over the evaporator 30 and its fins to be further cooled and thereby to lose more of its water vapor. The evaporator housing 32 directs all air over the evaporator 30 and back to the blower inlet 18 regardless of whether it was diverted through duct 24 or returned from the refrigerated space at opening 33.

In order to control the proportion of air diverted by 22 to duct 24, I have provided the humidistat 34 in the refrigerated space 36 of the cabinet. When the humidity in space 36 rises the humidistat moves the vane 22 to divert more air to duct 24, whereby the humidity of space 36 is brought back to normal. In some designs it may be preferred to use a fixed opening at 22 and regulate the air flow through 24 by means of a damper such as 38, in which case the humidistat will be connected to actuate this damper in place of actuating thevane 22.

FIGURE 2 shows the motor 40 which is hidden in FIG. 1, but can be identified by its shaft 12. FIGURE 2 also shows the outlet 20 at the bottom of casing 16 instead of at the top. In FIG. 2 the force of gravity is added to centrifugal force, making a small gain in the separation of moisture from the air, but the choice between the two arrangements will be mainly on convenience of location of drain tube 28 and the

ducts

20 and 24. FIGURE 2 shows damper 38 controlled by 34', which is either the humidistat or a relay actuated thereby, as suits the cabinet design. It will be understood that this is optional in any of the figures. Likewise the duct 24 may leave casing 16 tangentially as in FIG. 1 or at one side as in 'FIG. 2, whichever fits best into the design of the cabinet.

The location of the side outlet to 24 in FIG. 2 has an additional effect tending to separate a lighter portion of the air for recirculation over the evaporator. A similar effect can be obtained at any bend of conduit 20, where the denser air and water vapor mixture Will tend to follow the greater radius and the air mixture making the sharper bend will be the warmer and wetter mixture of which a portion is diverted to the conduit 24.

FIGURE 3 shows how the apparatus of FIGS. 1 0r 2 may be connected to regulate humidity in one or both compartments of a two-zone refrigerator. It also shows an axial flow fan 10 in place of the centrifugal fan 10 of FIGSl and 2. Either type of fan causes some centrifugal separation of the air stream due to the whirling effect and may be used in any of the figures. As will be seen from FIG. 3, the one evaporator and fan may be used to cool two separate compartments from which air returns to housing 32 at ports '33 and 33"instead of at a' single port 33, as in FIG. 1. The selection of which space (such as main food space or freezer) is to be cooled is made, by the switch 42, which is preferably operated thermostatically to close the left-hand contact when the main food space 36 is to be cooled and the righthand contact when the freezer is to be cooled.- A temperautre rise of the left-hand (freezer) bulb 52' closes the right-hand contact and of the right-hand (main food space) bulb closes the left-hand contact. These bulbs may be in their respective compartments or in the air ducts connected with them. 7

Assuming now that the thermostatic switch 42 is moved to the left in response to a rise of temperature of bulb 36 in the main food'compartment 36, this energizes motor 40 but does not move damper 44 since solenoid 46 is not energized. It does start the condensing unit 47 by energizing the relay switch 48, thus evaporator 30 is cooled and motor-40 drives fan 10' at. full speed, delivering cooled air through duct 50 which goes to the main food space 36 while return air enters housing 32 at 33'.

As in FIGS. 1 and 2, duct 24 bypasses a lighter (warmer and/or more humid) fraction of the air to housing 32 under control of damper 38 for further cooling and dehumidificationf The damper 38 may be assumed to rest in its closed position when relay 34' is not energized and to be opened as the humidity increases at the humidity-responsive device 51 to divert air through. duct v24 for further removal of water vapor by recooling.

Assuming now that the air temperature of freezer 52 rises' 'to the point at which the left-hand bulb 52' of switch 42 causes the switch to close the right-hand contact, current flows through solenoid 46 in series with motor 40, causing damper 44 to move to position 44' and motor 40 to operate at reduced speed. The relay 48, being designed to operate at either full or reduced voltage, starts the motor of condensing unit 47, which operates at full line voltage. Because of the lower air velocity over evaporator 30 the air now flowing to fan 19"will be colder'and lower in absolute humidity than when cooling thewarmer main-food compartment 36 to which air is delivered through ductf'50. These compartments are indicated in FIG. 3,'as 36 and 52-, being separated by the insulated wall 54.

The'liquid control assembly 55 comprises a receiver 56, a solenoid valve 57, a main rest-rictor58 and 'a bypass restrictor 59. During normal cooling of evaporator 30, with air directed to the non-freezing compartment 36, liquid refrigerant flows from receiver 56 through the open'valve 57 and restrictor 58 to evaporator 30. When switch 42 moves to its right-hand position, energizing solenoid 46 and thereby moving damper 44 to position 44 the mercury switch 60 closes its right-hand contact to energize solenoid valve 57, thereby closing it, which causes liquid to collect in 56 until it reaches'the level of outlet to 59, With this liquid trapped in 56 the evaporator 30 operates with less liquid in it and therefore at a low- ,er temperature with evaporation occurring in less of its length.. Thus evaporator 30 is operated at a relatively high temperature and full capacity while cooling the wmmer compartment 36 but at a lower temperature and capacity while cooling the freezer compartment 52'to which air is delivered'through duct 62.

The valve 57 is'further arranged to be closed when energized by the closing of contact in humidistat 51, which is located as shown in duct 50, in compartment 36 or in A duct 33 leading from 36. This humidista tic switch 51 closes in response to a rise of humidity of air flowing through compartment 36 and causes solenoid valve 57 to close, thus reducing the operating temperature of evaporator 30 to condense more moisture from the air being included in it an additional flow restricting means which,

when energized, reduces the liquid flow so that the evaporating pressure is right for cooling the freezer'52. The device may be identical with valve 57 plus a restricted by-pass such as a weighted check valve or a capillary tube such as 59.

Another optional arrangement is to employ a solenoid acting directly on the expansion valve in the direction of restricting its opening or urging it in a closing direction. A direct mechanical connection between 51 and the expansion valve may be employed, omitting the electrical'connection, if the design allows these parts to be placed closer together. For instance. the humidity responsive element of 51 may be a material, such as wood, which expands in response to a rise of humidity and acts to urge, the expansion valve in its closing directlon to reduce the evaporator pressure. This would be an expansion valve operating much like the thermostatic type but restricting flow in response to a rise of humidity of air instead of the usual response to a drop of temperature at the evaporator outlet.

When solenoid 46 is energized by movement of switch 42 to the right the damper 44 moves to position 44 and mercuryswitch 60 closes the contact between its middle and right-hand terminals, thus energizing 57 to cause evaporator 30 to operate at its lower temperature, regardless of Whether or not humidistat 51 has closed its contacts. At the same time the left-hand terminal of 60 is disconnected from the middle one causing 34' to be deenergized, allowing damper 38 to close. Ai-r flow is now through duct 62 to the freezer compartment 52.

Due to solenoid 46-now being in series with motor 40 the speed of fan 10 is reduced as is theair flow through evaporator 30. With the air velocity thus reduced there will be less by-passing of air through duct 24 even though damper 38 may be allowed to remain open. Normally the effect of the position of damper 38 may be neglected while cooling the freezer, but the designer may arrange the damper 38 to assume either open or closed position, or to be actuated in response to changes of freezer humidity while damper 44 is in the position 44'.

supplied to compartment 36. Under this condition the latent heat removed from air by 30 is increased and the amount of specific heat which it'removes is reduced to bringthe relative humidity of compartment 36 down to the desired maximum.

It'is thus seen that the one evaporator 30 serves selectively to cool the freezer 52 while operating at a low temperature, to cool compartment 36 while operating at a higher temperature, and on occasions of high humidity to cool compartment 36 while operating at a low temperature; Since

bulbs

36 and 52 oppose each other in operating switch 42 the cooling effect of the one evaporator 30 is directed to whichever

compartment

36 or 52 is in the greater need of refrigeration. After the compartment being cooled is reduced to the temperature at which switch 42 opens the contact for that compartment the switch immediately closes its other contact in case the other compartment is calling for refrigeration.

The above descriptioncovers the use of liquid control assembly 55 which, as shown, feeds liquid directly to evaporator 30. This is one of several arrangements from which the designer may choose for the purpose of cansing evaporator 30 to operate at high and low temperatures as required. One alternative is to employ an expansion valve, which is fed with liquid from receiver 56; This valve operates normally to feed evaporator 30 at a proper pressure for cooling compartment 36 but has When a single evaporator is used, as shown by 30, it is immaterial whether or not there are two duct openings 33' and 33" into housing 32, as the return air'ducts from the two refrigerated spaces may join to enter 32 at 33 as in FIG. 1. It will be apparent that in some designs there may be two evaporator-s 30 and/or-fans 10 or 10'. 'It will also be apparent that with one fan the'warmer evaporator of a two-temperature system may be located in the return air duct leading to opening 33' and the freezer evaporator in the 'duct leading to 33". Also there may be two fans 10 or 10' or one of each type with one or two bypasses 24-and dampers 22 or 38. With separate fans or blowers, one delivering air to duct 50 and the other to duct 62 the damper 44 and solenoid 46 may be omitted, whether one or two evaporators are employed. Also each fan will be of the right capacity for its job and neither fan motor will need the two-speed feature. No showing of a two-temperature system is deemed necessary herein as many such systems are known, including those shown in US. Patents 2,359,780; 2,375,319; 2,425, 634; 2,540,343; 2,641,109; 2,695,502; 2,709,343 and 2,765,633 issued to the present applicant, with more applications'pending. r

The switch 66 is assumed to have remained in its fullline position throughout the foregoing description. It is operated periodically by any of the known methods (manuaL'elapsed time, running time, temperature, frost thickness etc.) to cause defrosting of evaporator 30 or the colder evaporator. of a two-temperature system. The device 68 is energized when switch 66 is moved by any of the known defrost control methods to make its bottom contact. This movement of switch 66 breaks the circuit through relay 48, hence neither the fan 10' nor the condensing unit 47 operates while'defrost device 68 is energized, as shown in FIG. 3, however incertain defrost methods the condensing unit may be operated, in which case the device 68 will close the compressor motor circuit of condensing unit 47. In most such cases the fan motor 40 will be idle during the defrost, but where there are two fans and fan motors and a two-temperature system with hot gas or reverse cycle defrost is employed, one evaporator may be cooled and its fan kept running while the other (colder) evaporator is defrosted. Such might be the case in a system as shown in US. application Serial Number 247,239 filed September 19, 1951, by the present applicant. I

The device 68 represents any known type of defrosting system. The current supplied to it may actuate a valve for hot refrigerant (gas or liquid) defrost, be used to' heat the evaporator by the electric resistance method, start and operate the system as a heat pump to defrost the evaporator, move a damper, door, drawer, evaporator, baffle, etc., or do anything required to actuate any sort of defrosting device by any known method.

No matter what defrosting method is employed, some means must be provided for the disposal of the resulting water of meltage. The drain 70 may connect with any suitable container or water disposal device, preferably one which re-evaporates the drip water to ambient air.

This method of centrifugal separation of an air stream normally employs lower air velocities and pressures than are used in the Hilsch, Ranque or Vortex tube devices. It is preferred to employ the lower velocities produced by normal fans for economy reasons and to avoid undue noise, making no attempt to obtain a cooling effect by the dense air method of compression and expansion. It is, however, the scope of this invention to employ such higher air velocities and pressures with suitable changes of porting where this can be done with reasonable efliciency and without undue noise.

It will be understood that the humidity-responsive element 51 may optionally be located in any of several positions, where it is exposed to the air in the food storage space, air flowing toward the space or air flowing from the space. The humidistat 34, element 51 or 34' will be provided with suitable adjustment means whereby the user may set it to hold the humidity of the storage space air within desired limits.

As used herein the term humidity generally refers to the relative humidity of air, but it is understood that the humidity-responsive element 34, 34' or 51 may respond to wet-bulb temperature, dew point, absolute humidity, etc., according to the designers choice and preference for control elements.

Optionally the switch 60 may be connected to hold damper 38 open while air flow is directed to duct 62 whereby the full flow of by-pass air through duct 24 is maintained while the freezer is being cooled, thus providing further for delivering colder air to the freezer.

This method of humidity control is not to be confused with the by-pass, recirculation or reheat methods, used in air conditioning for human comfort. These older systems recirculate some of the warmer return air from the cooled space back to the cooled space, whereas in the present invention it is a part of the freshly cooled air which is recirculated a second time over the evaporator. In the reheat method, as the name indicates, air which has been cooled to a lower temperature than desired is actually heated before delivery to the conditioned space, whereas the present method is one of re-cooling.

I claim:

1. In a refrigerator having two storage compartments, a refrigerating system including an air cooling element, air-circulating means for moving air into heat exchange with said element and to one or the other of said compartments, air flow directing means for selectively guiding the flow of air to one at a time of said compartments, and air flow velocity modifying means made effective during delivery of air to one compartment for increasing the duration of said heat exchange and thereby the cooling and dehumidifying effect to which said air is subjected, thus delivering colder and drier air to said one compartment.

2. In a refrigerator, a food storage compartment adapted to be maintained within a range of temperatures above 32 F., a second compartment adapted to be maintained within a range of temperatures below 32 F., a refrigerating system, an evaporator forming a part of said system, air circulating means for moving air into heat exchange with said evaporator and through one of said compartments, air flow diverting means whereby the air after heat exchange with said evaporator is directed to the other of said compartments, a bypass for returning a less dense part of the air leaving said evaporator to flow in heat exchange with the evaporator a sec 0nd time, and a control responsive to an air condition of one of said compartments for regulating the flow of air through said bypass.

3. In a refrigerator-freezer cabinet, a non-freezing storage compartment, a frozen food storage compartment, a refrigerating system including an evaporator operative selectively at low or medium temperatures, air flow means for causing circulation of air over said evaporator, means for directing air circulation from said evaporator exclusively to the non-freezing storage compartment of said cabinet while the evaporator is operating at a medium temperature and for directing air circulation from said evaporator exclusively to frozen food storage compartment of said cabinet while the evaporator is operating at a low temperature, the whole being operable to maintain a lower absolute humidity in the frozen food compartment than in the non-freezing compartment.

4. In combination with a refrigerator having a freezer compartment and a non-freezing food storage compartmerit, a refrigerating system including an evaporator, power means for circulating air over said evaporator and selectively to one or the other of said compartments at a time, temperature-responsive means for selecting the compartment to which air is delivered, and means for modifying the rate of air circulation to move air more slowly over said evaporator while it is being delivered to the freezer compartment.

5. In a refrigerator having two food storage compartments, a refrigerating system employing a volatile refrigerant in a single evaporator for cooling said compartments, one of said compartments being a freezer maintained below freezing and the other a food compartment maintained above freezing, power-operated means for circulating air over said evaporator, flow controlling means whereby the major flow of said air is selectively directed through one or the other of said compartments and back into heat exchange with said evaporator, bypass means for recirculating a wetter portion of said air to be cooled again by the evaporator before delivery to a compartment, thermostatic means for regulating said system and flow controlling means in accordance with the respective needs of said compartments to hold each of them within its pre-selected temperature limits, and control means responsive to variations of humidity of air supplied to one of said compartments for regulating the operating temperature of said evaporator and said by-pass, whereby the humidity of air in the last said compartment is regulated.

6. In a refrigerator having two storage compartments including one for sub-freezing storage and one for abovefreezing storage, a refrigerating system including a single evaporator for cooling said compartments, air duct means connecting said evaporator with both said compartments, damper means for selectively closing the air ducts leading to said compartments one at a time to cool the other compartment, motor-operated means for circulating air through said duct means, and control means for reducing the rate of air circulation over said evaporator while air is delivered to one of said compartments with respect to the rate at which air is circulated over it while delivered to the other compartment. v

7. In a refrigerator including a refrigerating system, a freezing compartment for frozen foods, a warmer compartment for non-frozen foods, an evaporator vfor cooling air for said compartments, a fan for circulating air in heat exchange withsaid evaporator and selectively through one only of said compartments at a time to cool it, a humidity responsive device located in the path of air circulated through said warmer compartment, a control device for modifying the operating temperature of said evaporator, means connecting said humidity responsive device with said control device to regulate the humidity of air in said warmer compartment, and control means responsive to temperature changes of said compartments to select the compartment to be cooled, said control means including means for causing said evaporator to cool air to a lower temperature for said freezing compartment than it normally cools the air for said warmer compartment. 7

8. In an air treating apparatus, a fan, a housing for said fan,'an inlet to said housing for air and Water vapor mix.- ture, an outlet irom said housing for treated air and Water vapor mixture, a second outlet leading from said housing, means for collecting a less dense portion of the mixture leaving said fan and delivering it to said second outlet, and means responsive to, changes of humidity of air discharged through the first said outlet for regulating the flow of air through said second outlet.

9. In an air treating apparatus, a fan, a housing for said fan, an inlet to said housing for air and water vapor mix tnre, an outlet from said housing for treated air and water vapor mixture, a second outlet leading from said housing, means for collecting a less dense portion of the mixture leaving said fan and delivering it to said second outlet, means responsive to changes of humidity of air discharged through the first said outlet for regulating the flow of air through said second outlet, and means for draining from said apparatus all Water separated therein from said air and Water vapor mixture.

10. In a refrigerator having freezing and non-freezing compartments, a refrigerating system including evaporator means for cooling air for said compartments as required to maintain a suitable temperature in each, air flow control means for selectively directing air over at least a portion of said evaporator means and thence to one or the other of said compartments, and means for modifying the flow of air relative to said evaporator means in response to changes of humidity in one of said compartments for the purpose of selecting and recooling a more humid portion of the air before it is delivered to said one of the compartments.

References Cited in the file of this patent UNITED STATES PATENTS 1,737,040 Bulkley et a1 Nov. 26, 1929 2,107,268 Averyet a1 Feb. 8, 1938 2,133,334 Rosett Oct. 18, 1938 2,166,813 Gibson July 18, 1939 12,236,190 Wolfert Mar. 25, 1941 2,685,433 Wintermann Aug. 3, 1954 2,763,982 Dega Sept. 25, 1956 2,773,356 Coblentz Dec. 11, 1956 2,783,623 Dodge d Mar. 5, 1957 2,812,642 1957 Jacobs Nov. 12,