US2904254A - Cooling and humidifying system - Google Patents

Description

United States Patent COOLING AND HUMIDIFY IN G SYSTEM fAgnew H.'=Bahnson, J r., and'William-=W..Avera, instan- Salem, N.C., assignors to The 'Bahnson Company, -Winston-Salem, N;C., a corporation'of North Carolina Applicationllanuary 12, "1954, Serial No.-403,s07

-4 Claims. tomes-44 This invention relates to a cooling and 'humidifying system which is particularly adapted for a'textile weave room or other shop in which .considerable lint, size 'or .dirt is .entrained in the air.

In air conditioning systems using outsideair for cooling in the summer time, provisions are made to recirculate roomair through "the fans and humidifiers so that the desired room temperature can "be maintained. These systems are designed such that thetan handles a constant air quantity which means thattherecirculating dampers will :modulate'to the open position while the fresh air dampers will modulate to the closed position and vice versa. This "feature is present in both the central statio'nand wet duct type systems. The object of this'particular arrangementisto reduce'thesteam consumption'by the utilization of room in cool weather. It has been found that the expected economy is not obtained in the case of air conditioningfor weave rooms and other shops or :mills in which considerable lint, size, and/or other dirt is entrained in the air as the cost of cleaning the screens or filters which cover therecirculated air opening oflsets the savings due to a lower steam consumption.

An object of the present invention is to provide an air conditioning system for mill rooms, and especially for weave rooms which is more economical in operation than the prior systems. An object is to provide an efiicient humidity and temperature control system which is characterized by an absence of any recirculation of the'room air through a humidifier unit. An object is to provide a humidity and temperature control system for weave rooms in which there is no recirculation of-room air and the introduction of freshclean air is limited substantially to that which is employed .for cooling to maintain a preselected maximum temperature.

More specifically, objects are to provide a process and equipment for controlling the humidity and temperature which are characterized byhumidifiers within the room to maintain a desired relative humidity and a duct system and'fan for introducing fresh air into the room, the quantity of fresh air so introduced being regulated by a room thermostat to that quantity required for evaporative cooling to maintain the room temperature below a selected value or to prevent back flow into the duct system when no cooling is required.

These and other objects and the advantages of the invention will be apparent from the following specification when taken with the accompanying drawings in which the twoviews are fragmentary andsomewhat schematic plan views of Weave rooms provided with humidity and temperature control systems embodying the invention.

humidifier system 9 of the central station type. auxiliary humidifier system may be-of-thetype described ,and claimed in prior Patent No. 2,262,542, Agnew H.

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pletely closed except for outwardly openingxlouvergrnot shown,.for theventing of air from theroom whenoutsideair is-introduced. 'Water'is evaporated'directly into the room air under control of a-humidostat -2to maintain .a desired relativehumidity (within the room. :Asvshown .schematically, the humidifier units comprise atomizers .3 on a .pipe line 4 which is supplied with waterthrougha control .device5 that is regulated by .any .desired form of electric or compressed air control line 6 from the vhumidost-at .2. The individual atomizers 3 are preferably arranged adjacent the outlets 7 of a duct8 of a separate This Bahnson, Jr. and .theairinlet tothe system is entrance cham'berlt) which is .closed except foropenings to the outside air which are .provided with louvers 11 and 12 respectively, the louvers 11 being in:front of a heater A multi-speed fanF is driven .by a.motor.:14.to .force ,air through the evaporator section 15 of .thehumidifier .of water .fromthe moist air stream. .A-room thermostat 17 operates-through control line 18 .and aIvariablelspeed control device '19 to regulate the speed of fan 14 in :accordance with the demand for. cooling to, prevent the temperature of the roomlair 'fromris'ingabove a preselected maximum value, .and .a branch control .18 extends from thermostat '17to the operators T11 and 12. of .thelouvers '1'1 and '12respectively to open the ,sameprogressively 'in accordance with the increasing fan speed.

Water is supplied to the evaporator section 15 through a modulating valve 20 in thepipe $21, the valve 20 being controlledthrough a line 20"by a.duct thermostat 26 in series with anientrainment control ,hygrostat 27. The duct thermostat'ZGis set'to reducethe supply of .water to the evaporators I5 whenthe duct temperature is decreasing and approaching the room dew point. .A supervisory control is alsoimposed upon the water valve 20, namely a relay 22 is includedin controlline 20 to close the valve completely in theevent that the fan motor "14'is de-energiz ed through the starter 19 ,'the relay 22'being of known electroepneumatic type and energized through a control line '22 connected to contacts of the variable speed controLmotor starter 19.

So long as'thetemperature withinthe room is below thedesired value, the central station system 9 is deliverin g only enoug'h air "for ventilation; this minimum air quantity produces a slight "overgpressure in "the duct 8 and prevents .a reverse flow 'of room "air into the "duct. This feature eliminates a serious cleaning problem .as a reverse flow of room air. into the duct 'Would'depos'it dirt'within the 'duct. Althoughthe'relay 221s "energized, since electrical power is available at the motor starter "19 and the fan 'Fiis :in operation, 'the'water 'modulatin'gwalve 20 is closed or substantially closedibythe'duct thermostat 26 and entrainment control hygrostat"2'7 however these instruments "are capable "of opening thewater valve '2 to 'fullvolum'e should'their set points be" exceeded. the room temperature :reaches the selected value, the thermostat 17 "operates through the 'variaiile speed control 19 to increase the fan speed. At the same time, the room thermostat 17 operates through the control line 18' to start the opening of the louvers 11 and 12 to admit outside air to the entrance chamber 10. The water valve 20 is positioned to an appropriate degree by the dust thermostat 26 in response to fluctuations in temperature brought about by the louver movements and the steam coil. When control 19 is adjusted for maximum fan speed, louvers 11 and 12 are fully open, the water valve 20 will be wide open'if the outside wet bulb temperature is above the duct thermostat 26 setting, and the air volume has reduced the entrainment to a point below the setting of the entrainment control 27.

A wet bulb thermostat 23 may be mounted at the outlet side of the eliminators 16 to open valve 24 in steam line 25 to heater 13. This arrangement allows more evaporation to take place in the washer chamber 9, thus reducing the load on the room evaporators. The setting of the wet bulb thermostat may be below the room dew point, therefore a dry bulb thermostat 26 must be provided to prevent condensation on the duct in the room. The duct thermostat 26 limits the amount of evaporation such that the resulting temperature is above the dew point of the room and condensation will not occur.

The variable fan speed may be obtained in different manners, for example by employing a variable speed me chanical or fluid drive between a constant speed motor and the fan or, as shown schematically, by employing a step-by-step control 19 between a current source S and the motor connections L to regulate the fan speed.

Advantages of the described system are economy in the operation of the system since there is no recirculation of room air through the central station humidifier system and therefore no necessity for a periodic cleaning of lint and dirt from the filters employed in the recirculation types of humidifiers, and economy through the use of variable speed fans to handle only a limited quantity of air in proportion to the heat load to be dissipated.

Many elements of the embodiment shown in Fig. 2 are or may be identical with those of Fig. 1 and are identified by like reference numerals but will not be described in detail. The major difference between the two systems is that the motor 14 which drives fan F of Fig. 2 may run at constant speed as the control of the quantity of fresh air introduced through duct 8 for room cooling is through regulation of the relative positions of exit louvers 28 and by-pass louvers 29 by the room thermostat 17. The common operator 30 for the louvers is energized by thermostat 17 through the control line 18, and the sets of louvers are so connected by a linkage 31 that the louvers 28 open as louvers 29 close, and vice versa.

The exit louvers 28 are a refinement of the system and may be omitted since, when the fresh air dampers are closed and the by-pass louvers 29 are fully open, i.e. when there is no demand for room cooling by the room thermo stat 17, only such fresh air as leaks through the fresh air dampers flows through the duct 8 for ventilation of the room.

The operators 11', 12 of the sets 'of inlet louvers 11 and 12 respectively are controlled by room thermostat 17 and control line 18 through separate relays 32 and 33 in such manner that louvers 11 in front of heater 13 open during cold weather when a minimum amount of cooling is required and the louvers 12 open after the louvers 11 are fully open.

In the operation of this embodiment of the invention, the primary supply of moisture to the room air is through the atomizers 3 under control of the humidostat 2.

So long as the room temperature is below the preselected normal value, the outlet louvers 28 are closed and the by-pass louvers 29 are fully open, thereby returning substantially all air which passes through the auxiliary humidifier system back to the inlet fan F. The on-otf control of modulating valve 20 in the water supply pipe 21 is established, as in the Fig. 1 system, by a relay 22 which is energized from the motor starter 19 to insure that the water supply will be cut off in the event of a failure of electrical power. If the water were not cut off upon a failure of the fan, there would be a back flow of spray from the fan inlet into the chamber 10. The motor 14 is preferably in operation to maintain a slight pressure in duct 8 to prevent room air from entering and depositing dirt in the duct. Upon a rise in room temperature, thermostat 17 operates through control line 18 progressively to close louvers 29 in accordance with the demand for cooling, and simultaneously to open the louvers 28 if such exit louvers are included in the system; and through control lines 18 to open the inlet louvers 11, 12.

The operation of the supervisory control elements, i.e. wet bulb thermostat 23, duct thermostat 26 and hygrostat 27, may be substantially as previously described or the wet bulb thermostat 23 may be omitted by imposing the control of valve 24 in the steam line to heater 13 upon the duct thermostat 26. The steam valve will work in sequence with the water valve to maintain the duct temperature.

It is to be understood that it is not essential that a constant speed motor be employed in the Fig. 2 system in which the regulation of the fresh air introduced into the room is based upon a diverting of some of the available air back to the fan inlet, and that considerable economy in power costs can be effected by employing a multispeed motor and controlling the motor speed in accordance with the demand for cooling. Furthermore, in place of running fan F continuously at low speed to prevent room air from hacking into duct 8 and depositing dirt, a separate small fan may be operated continuously in chamber 10 to prevent reverse flow of room air into the duct and the fan F need then be operated only as required for introducing fresh air into the room for evaporative cooling.

It is thus apparent that there is considerable latitude in the construction and operation of apparatus contemplated by the present invention and falling within the scope and spirit of the following claims.

We claim:

1. In a ventilating and humidifying system for a room, the combination with humidifying means within the room, and humidity responsive control means within the room for regulating the operation of said humiditying means to maintain a desired relative humidity within said room; of an auxiliary humidifier system of the central station type having a humidifier unit between outlet means opening into said room and inlet means communicating with the outside air, a continuously operating fan for drawing outside air through said inlet means and discharging it through said outlet means after passage through said humidifier unit a hygrostat at said outlet means, means controlled by said hygrostat to limit the water supplied to said humidifier unit to the quantity which is completely evaporated in the fresh air in transit to the room, and a modulating means actuated by a thermostatic control device within the room for regulating the quantity of outside air introduced into the room through said auxiliary humidifier system in accordance with the extent to which the room temperature exceeds the preselected value, said modulating means always maintaining at least a minimum flow of fresh air to said outlet means notwithstanding temperature conditions in the room thereby to maintain a slight overpressure in the ducts leading to said outlet means and preventing any back flow of room air into said outlet means.

2. In a ventilating and humidifying system, the invention as recited in claim 1, wherein said modulating means includes adjustable louvers in said inlet means of the auxiliary humidifier system.

3. In a ventilating and humidifying system, the invention as recited in claim 1, wherein said modulating means includes louvers at the outlet means of said auxiliary humidifier system and adjustable to regulate the relative quantity of air which is discharged into the room and that which is recirculated through said awdliary ,874,964 Goes Aug. 30, 1932 humidifier unit. ,943,613 Lewis Jan. 16, 1934 4. In a ventilating and humidifying system, the in- 2,016,091 Karlson Oct. 1, 1935 vention as recited in claim 1, in combination with a ,128,096 Loepsinger Aug. 23, 1938 supplemental thermostatic control device at said out- 5 2,226,815 Haines Dec. 31, 1940 let means, and heating means energized by said supple- 2, 82,013 Wetzsteon May 5, 1942 mental thermostatic control device for heating the air ,681, 82 McGrath June 15, 1954 in transit through said central station humidifier unit to OTHER REFERENCES maintain the moist fresh air discharged into the weave room at a temperature above the dew point of the moist 10 air already present within the weave room.

Haines: Page 315 of Automatic Control of Heating and Air Conditioning by John E. Haines, pub. 1953 by McGraw-Hill Book Company.

References Cited in the file of this patent UNITED STATES PATENTS 1,751,805 Fleisher Mar. 25, 1930 15

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