US2574298A

US2574298A - Heat exchanger clothes drier

Info

Publication number: US2574298A
Application number: US717432A
Authority: US
Inventors: Thomas R Smith
Original assignee: Maytag Corp
Current assignee: Maytag Corp
Priority date: 1946-12-20
Filing date: 1946-12-20
Publication date: 1951-11-06
Anticipated expiration: 1968-11-06

Description

Nov 6, 19.51 T, R, sMlTH 2,574,298

HEAT EXCHANGER CLLoTHI-:s DRIER Y Filed Dec. 20,1946l 2@ 2o J4 i@ zz 12 Patented Nov. 6, 1951 HEAT EXCHANGER CLOTHES DRIER Thomas R. Smith, Newton, Iowa, assignor to The Maytag Company, Newton, Iowa, a corporation ol' Delaware Application December 20, 1946, Serial No. 717,432

6 Claims.

The present invention relates to a material drying unit and more particularly to a novel heat exchanger and to a novel system for drying clothes or other material.

Among the objects of the present invention is the provision of a novel means and manner of drying clothes within a self-contained and closed system employing a novel principle of heat, exchange.

'I'he invention further comprehends a novel manner of drying clothes which may be carried out either at room or ambient air temperature or at an elevated temperature if it is desired to sterilize the clothes or to raise the temperature thereof for other reasons.

A further object of the invention is to providea closed heat exchange system for removing mois-- ture from'materials wherein the pressure is lowered to cause evaporation of the moisture at one location and raised to cause condensation at another and wherein a portion of the heat released by condensation is utilized to evaporate additional moisture.

A still further object of the present invention is the provision of a novel manner of drying clothing or other material including an enclosure or chamber for the material to be dried, an enclosure or chamber in which the moisture removed from the material is condensed, and the novel steps of adjusting and controlling the temperature or pressure or both in these enclosures to thereby control the gaseous and vapor pressures therein, whereby to cause moisture to be removed by vaporization from the materials in the one chamber and to collect and condense such moisture in the other chamber, transferring heat of condensation of the liquid vapor in the condensing chamber to the chamber containing the materials to be dried, and continuing these steps until the desired quantity of moisture has been removed from the materials.

Further objects are to provide a drying system of maximum simplicity, elciency, economy and ease of operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

The invention further resides in the illustrated combination and arrangement of parts and in the novel operation described, and while there is disclosed therein a preferred embodiment, it is to be understood that the same is susceptible of modification and change, and comprehends other details, arrangements or parts, features and constructions without departing from the spirit of the invention.

Figure 1 shows in vertical cross-section and somewhat diametrically a clothes drier unit for carrying out the novel method.

Fig. 2 is a view similar to Fig. l showing a second embodiment of the improved drying method.

Fig. 3 is fragmentary sectional view taken on the line 3--3 of Fig. 2, and

Fig. 4 is fragmentary view showing a modiiled form of heatingy means for the enclosure.

Referring to Fig. 1, there is disclosed a novel heat exchanger means for drying clothes or other materials comprising a unit assembly I enclosed within an insulated compartment 2 and provided with a door or closure 3. This door permits access to the interior of an evaporating chamber or enclosure 4 for receiving damp clothes or other materials 5 to be dried. The clothes or other materials within the evaporating chamber or enclosure 4 may be tumbled or agitated by any suitable means such as a tumbler 22 or agitating means to cause contact of the clothes with the surrounding walls of the chamber 4 as well as with the gases therein. Encompassing the chamber 4 there is shown heating means in the form of a coil 6 for receiving a iluid, such as steam or hot water, for supplying heat to the chamber. The heat supplied to the coil is under the control of an adjustable temperature responsive control valve 23 which responds to the temperature in the chamber. Thus by adjusting this valve any suitable temperature may be selected and maintained in the chamber 4 for the drying operation. If the operation is to be carried on at room temperature the heating coils need not be employed, but if it is desired to dry the clothes or materials at a temperature higher than ambient air temperature or if they are to be sterilized during this operation then the heating coil is employed for elevating the temperature in the chamber to that desired.

A vacuum pump l driven by a motor 24 is connected by means of a conduit 25 tothe chamber 4,'for applying a suction to this chamber for reducing the gaseous pressure therein. The amount of evacuation may be controlled by means of an adjustable pressure responsive switch 26. which automatically stops the vacuum pump by de-energizing the motor 24 upon the attainment of a predetermined low pressure. A valve 21 placed in the suction conduit 25 is used to put the chamber 4 in communication with the vacuum pump -in one position, and to place it in communication with the atmosphere in a second position when the drying operation has been completed. Also connected to the chamber 4 is a pump 8 for exwith valve I3 for controlling the discharge.

If tle drying operation is to be operated at substantially atmospheric pressure, the valve 21 is lett in the position shown and the vacuum pump I is not energized; however, during operation oi the pump I the chamber 4 is under a subatmospheric pressure while the condenser is at a pressure somewhat higher.

Encompassing the chamber 4 is a chamber or enclosure I4 connected by passageways Il and I6 to a chamber or enclosure I9 encompassing or surrounding the condensing chamber I4. This chamber or enclosure I9 is connected to passageways I1 and to the chamber I4 through a pump I9. The pumps 9 and I9 are shown suitably insulated and are driven through belting l* and I9l in any suitable manner, such as, for example, by a motor 23. 'I'his motor as shown is also used to rotate the tumbler 22 through the belt 22". It is to be understood that the particular manner of driving these pumps forms no part of the invention.

In order to terminate or control the operation of theA apparatus, an adjustable humidity responsive control switch 29 is provided for accurately determining the humidity and to stop the motor 29 by opening the electrical circuit 39 when the humidity of the gases in the chamber, and consequently the moisture content of the materials, has been reduced to that selected for the desired dryness. The adjustment of this switch is preferably made accessible to the operator and may respond either to the air in or leaving chamber 4.

In the operation of the drying unit, the door or closure 3 is opened and the wet clothes or materials to be dried are placed in the chamber 4 where they may be tumbled about by the tumbler or agitator 22, after which the door is closed and the valve 21 is placed in communication with the vacuum pump 1 (see Fig. 1) to thereby seal this chamber from the ambient atmosphere, and the humidity responsive switch 29 is adjusted for the desired dryness of the materials. Assuming that the temperature in the chamber 4 has been predetermined, the switch 29 is set for room temperature or if a higher temperature is desired the heating coil 6 supplies heat thereto under control of the temperature responsive valve 23. Under all conditions the gaseous pressure in chamber 4 will be equal to the sum of the air pressure and the vapor pressure at the temperature of operation. In order for the moisture to evaporate from the clothing or other material being dried, it is necessary that the gaseous pressure in the chamber 4 be less than the vapor pressure of the liquid in this chamber, and this is readily accomplished by reducing the pressure in this chamber by operating the vacuum pump l until such condition exists.

If the unit is to be operated at substantially atmospheric pressure. then the vacuum pump is not employed but the temperature is raised to the point where the vapor pressure is slightly above the gaseous pressure of the liquid in the chamber 4. If this temperature is too high for the materials to be dried, the vacuum pump is employed and an intermediate temperature is selected with its corresponding lower pressure to perform the proper drying operation.

When the gaseous pressure in chamber 4 is slightly less than the vapor pressure of the moisture in the material to be dried, pump 8 operates to withdraw vapor from the chamber 4 and u'. discharge it into chamber Il to cause a differential pressure between the chambers. This pumping action lowers the gaseous pressure in chamber 4 further. whereby the moisture in the material being dried vaporizes and is pumped into the chamber Il wherein the increased gaseous pressure will be above the vapor pressure of the liquid and thereby cause the vapor to condense and collect in the base of the chamber. As this vapor condenses in chamber I9, heat will necessarily be given oi! and as the moisture vaporizes in chamber 4 heat will necessarily be absorbed.

To utilize heat most effectively, the heat oi condensation in chamber Il is carried over or transmitted to chamber 4 to thereat replace the heat of vaporization. This is preferably accomplished by circulating air over and around the exterior of the condensing chamber III, through the pump I9 to the chamber I4 surrounding the evaporating chamber 4 and from there back through the chamber or passage I9 and into the passagesways I1 and chamber I8 surrounding the enclosure or chamber Il. To facilitate heat exchange, the enclosures or chambers 4 and i9 may bie provided with radiating ns 29 and 2 I, respect vely.

It will thus be apparent that by employing this principle of heat exchange in an insulated unit or enclosure, a more eillcient removal of moisture from the material or clothing 5 in the chamber 4 is effected than would be possible if all the heat required for vaporization of the moisture was supplied from some external source and then lost or carried away in the condensation chamber I0. With this system of heat exchange the only external heat required, after vaporization of liquid is initiated, will be that required to make up for the normal heat losses through radiation and incidental cycle losses. After the operation has been carried on sufiiciently long to remove the desired or required amount of moisture from the material or clothing to be dried, the humidostat control 29 responding to the humidity of the air in the chamber 4 is actuated and the operation is stopped. after which the valve 2l is moved to permit the pressure in the chamber to rise to atmospheric. 'I'he dried material or clothing may now be removed from the chamber 4 by opening the door or closure 3.

As will be apparent, the entire system is suitably insulated to prevent heat loss from one part 0f the system to another except for the heat flow path indicated, and is also insulated to the outside atmosphere when th door is closed so as to seal olf the unit. The vacuum pump 1 requires but limited power and may be of low capacity for the reason' that it is employed only to maintain the vacuum in the system, and pump I9 is employed merely to circulate air from the chamber I9 to the chamber I4 in order to accomplish the desired heat exchange.

Referring now to the embodiment shown in Fig. 2, there is disclosed a modiiied heat exchange structure which eliminates the pump I9, chambers I4 and Iland passageways I5, I6 and I1 without modifying the operation of the system and manner of drying clothes.

In this instance a drier unit 3I is enclosed within an insulated compartment 32 and it is provided with a door 33 to permit access to the interior of an evaporating chamber 34 for receiving the wet clothes 5 to be dried. These clothes may be tumbled by a tumbler 3l driven in any suitable manner through reduction gear means 3B. Heating means such as the coils 31 under control of an adjustable temperature responsive valve 38 is utilized to selectively control the temperature in the evaporating chamber 34. l

'I'he vacuum pump 3l driven by the motor 40 under the control of an adjustable pressure responsive switch 4i is utilized to control the pressure in the chamber 34, and a valve 42 selectively places the chamber either in communication with the vacuum pump or the atmosphere. Connected to and in communication with the chamber 34 is a pump 43 for withdrawing vapor therefrom driven by a motor 44 preferably under thecontrol of a humidity responsive control switch 45.

Encompassing the evaporating chamber 34 and having a common wall 46 therewith is a condensing chamber. 41 whose interior is connected to the discharge of the pump 43 for receiving the vapor removed from the evaporating chamber. In order to increase the heat transfer surface between the evaporating and condensing chambers, the wall 46 may be corrugated or convoluted in any suitable manner as best shown in Fig. 3. If it is desired to corrugate the entire wall, a screen 48 is preferably provided in the lower portion of the chamber 34 to prevent material from getting caught in the convolutions.

Disposed in the lower portion of the condens ing chamber 41 is a discharge conduit 4I having a valve 50 therein for draining condensate from the chamber when the drying operation is completed.

In the operation of this modification the wet clothes are placed in the evaporating chamber 34, the door 33 is closed and the valve 42 is placed in communication with the vacuum pump 39. The drying temperature is selected by adjusting the valve 33 and the humidostat 45 is positioned for the desired dryness of the clothes. The vacuum pump is motivated and it withdraws gases from the chambers and thereby reduces the pressure therein. After the gaseous pressure in the evaporating chamber has been reduced below the vapor pressure of the liquid in the materials, the liquid vaporizes and in so doing it absorbs heat and the pump 43 withdraws this vapor and delivers it to the condensing chamber 41 at'an increased pressure. This increased pressure is above the vapor pressure of the liquid, and due to this the vapor condenses and a portion of its heat is released. As heat is released it flows through the common wall 46 into the evaporating chamber 34 to vaporize the moisture remaining in the materials.

Thus it can be seen that as heat is removed from the evaporating chamber by vaporization of the liquid, at any selected pressure, it is returned thereto through the wall 46 when the vapor condenses and releases its heat in the condensing chamber.

In Fig. 4 there is shown a modified form of heating means for the evaporating

chambers

4 and 34. In this form the heating coils 6 and 31 and the control valves 23 and 3l are eliminated and an electrical heating element 50 is substituted under the control of an adjustable thermostat l.

From the above description and the disclosure in the drawings, it will be apparent that the present invention comprehends a novel heat exchange system for drying clothes or other materials in which is provided a completely ins or compartment for receiving the materials to be dried. Means are provided for evaporating the moisture from the material by adjusting the temperature or pressure or both of the gases enveloping the materials whereby the gaseous pressure in the enclosure containing such materials is less than the vapor pressure of the liquid to be removed, then conveying this vapor into a condensing chamber wherein the gaseous pressure is greater than the vapor pressure of the liquid and is therefore condensed, transferring some of the heat of condensation of the vapor being condensed from that chamber to the unevaporated liquid in the enclosure containing the material being dried, and continuing this operation in a closed cycle until a desired amount of liquid has been removed from `the material. Any suitable temperature and pressure indicating means may be provided for the drying chambers.

Having thus disclosed my invention, I claim:

1. A system for removing liquid from materials. comprising an enclosure for receiving said materials, means including a pump for controlling the pressure therein. means including a thermostat for controlling the temperature in said enclosure to maintain the gaseous pressure therein below the vapor pressure of the liquid to be evaporated and thereby cause a portion of the liquid to vaporize, means for withdrawing the vapor and non-condensible gases from said enclosure. a vapor condensing chamber for receiving the vapor and gases so removed and maintained by said withdrawing means at a gaseous pressure above the vapor pressure of the liquid in said enclosure. and a second pump for circulating air about the outer peripherles of the condensing chamber and the enclosure for transferring heat of condensation from said chamber to said enclosure to thereby assist in the vaporization of the liquid remaining in the materials in said enclosure.

2. Apparatus for drying clothes comprising an insulated unit including a sealed evaporating chamber having an opening for the reception of wet clothes, a separate condensing chamber in communication with the evaporating chamber and disposed in heat exchange relation therewith,

heating means for supplying heat to the exteriorof the evaporating chambrr for heating the interior thereof, temperature responsive means for controlling said heating means, a vacuum pump for reducing the gaseous pressure in the evaporating chamber below the vapor pressure of the liquid in the clothes at the temperature selected to cause vaporization of the liquid and thereby absorb heat. means for stopping the operation of the vacuum pump upon attainment of a predetermined low pressure, a pump for withdrawing this vapor from the evaporating chamber anddischarging it at an increased gaseous pressure in the condensing chamber, said increased pressure being above the vapor pressure of the liquid to thereby cause condensation of the vapor and a consequent release of heat, a heat exchange surface for transferring a portion of the released heat to the exterior of said evaporating chamber to aid in vaporization of liquid still remaining in the clothes to thereby conserve heat, and means depending upon the condition of dryness of the materials for terminating operation ot said pump.

3. A system for removing liquid from materials, comprising an insulated container sealed from the atmosphere and including an evaporatsuiated unit wherein is provided an enclosure 1s ins chamber for receiving said materials. a con- 7 densing chamber spaced from but disposed in heat exchange relation to said evaporating chamber, heating means for heating the exterior of said evaporating chamber. temperature responsive means for controlling the supply of heat by said heating means, a pump for initially evacuating said evaporating chamber to thereby reduce the gaseous pressure therein below the vapor pressure of the liquid in said materials and thereby cause vaporimtion o! the liquid, a second pump for withdrawing vapor from said evaporating chamber anddelivering it to said condensing chamber at an increased gaseous pressure with said pressure being above the vapor pressure oi' the liquid to thereby cause condensation, a heat exchange surface for transferring the heat of condensation back to said evaporating chamber for vaporization of liquid therein, means responsive to the condition oi' dryness of the materials for terminating operation of said second pump, and means for removing condensate from said condensing chamber.

4. An apparatus for removing liquid from clothes, comprising an insulated unit including a sealed enclosure provided with an access opening for the reception of the clothes and sealed when the apparatus is operating and an outlet for evacuating the enclosure, a condensing chamber communicating with andk in heat exchange relation with said enclosure, a vacuum pump connected te the outlet for reducing the gaseous pressure in said enclosure below the vapor pressure of the liquid to cause vaporization oi' the liquid and thereby absorb heat, means for operating the vacuum pump until a predetermined low pressure is obtained in the enclosure, means for withdrawing the vapor and delivering it to said condensing chamber at a pressure above the vapor pressure oi the liquid to thereby cause condensation of the vapor and a consequent heat release, a pump for transferring the released heat back to said enclosure for the vaporization oi additional liquid, and means responsive to the humidity in said enclosure for terminating op-l eration of said last named pump when the clothes have reached the desired dryness.

5. A clothes drying system having independent heat sources acting conjointly to evaporate liquids in an evaporating chamber for containing the clothes to be dried, said heat sources comprising an external heating source for heating the exterior of the evaporating chamber and a separate condensing chamber for receiv-A ing liquid vapor from the clothes to be dried and in which the liquid is condensed and removed, means for controlling the pressure in the evaporating chamber to cause the liquid te vapori therein. means 4for conducting the liquid vapor \1rom the' clothes in the evaporating chamber to the condensing chamber where the liquid is condensed, said vevaporating and condensing chambers being so constructed and arranged that heat of condensation is maintained within the system, and means ior circulating and directing the heat ot condensation about the evaporating chamber to assist in heating the latter for evaporating lany liquid remaining in the clothes.l

6. A clothes drying unit comprising an insulated container sealed from the atmosphere and provided with an evaporating chamber for receiving the clothes to be dried and a separate condensing chamber for receiving liquid vapor from the wet clothes and in which chamber the liquid is condensed and removed, and separate and independent heating systems operating conliointly to heat the evaporating chamber te evaporate and remove the liquid from the clothes to be dried, one of said heating systems being connected to an external source ior supplying heat to the evaporating chamber to raise the temperature therein te a predetermined level and the other comprising means for withdrawing vapors from said evaporating chamber and forcing said vapors into said condensing chamber, and means for recirculating a heat exchange iluid over said condensing and evaporating chambers whereby the heat of condensation from said condensing chamber is supplied to said evaporating chamber.

THOMAS R. SMITH.`

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS