US2739792A - Air conditioning systems using heat exchangers local to the conditioned space - Google Patents

Description

R. D. BLUM March 27, 1956 2,739,792 AIR CONDITIONING SYSTEMS USING HEAT EXCHANGERS LOCAL TO THE CONDITIONED SPACE 3 Sheets-Sheet 1 Filed Nov. 18, 1952 mm NH mm M wH E JOMFZOU QUPZ INVENTOR Roberl: Dblum fi & h

ATTORNEYS March 27, 1956 R. D. BLUM 2,

AIR CONDITIONING SYSTEMS USING HEAT EXCHANGERS LOCAL TO THE CONDITIONED SPACE Filed Nov. 18, 1952 3 shfiets-sheet 2 K J) 62 F16 3 61 "K J) 23 K L 4 24a 22 4' 5s I 63 F16.

E (C INVENTOR Roberc DBIum BY MLQL ATTORNEYS March 1956 R. D. BLUM 2,739,792

AIR CONDITIONING SYSTEMS USING HEAT EXCHANGERS LOCAL TO THE CONDITIONED SPACE Filed Nov. 18, 1952 5 Sheets-Sheet 3 lllllllllllllllllllllll 'mnmiununn ATTORNEYS United States Robert D. Blum, York, Pa., assignor to York Corporation, York, Pa., a corporation of Delaware Application November 18, 1952, Serial No. 321,183

7 Claims. (Cl. 2573) This invention relates to air conditioning of multistory multi-room buildings such as hotels, apartment houses, oflice buildings, hospitals and the like.

An important characteristic is that the load is carried by heat exchange units local to the room so that conditioned air, as such, is not distributed through extensive insulated duct work. The local units do not have any fans and fan motors. Use is made of air distributed under pressure to the units to perform two functions: (1) provide all ventilating air and (2) serve as a principal temperature changing medium and under summer conditions as a dehumidifying means.

The second function depends on local intensive conditioning of the supply air which flows in contact w th heat exchange surfaces local to each unit. In wimer these surfaces are heated by circulating heated liquid through them. In summer a cooled liquid is circulated, so that cooling and dehumidification of this supply air both occur. Water is the liquid customarily used for heating and for cooling. The supply air is intensively conditioned, but this conditioning is done locally. It is better to condition the supply air rather than air drawn from the room, or a mixture of this and supply air, as has been proposed heretofore. Local intensive conditioning saves losses in transmission such as are unavoidable when the intensive conditioning is effected at a central unit. Conditioning of the supply air assures adequate distribution of the very air which changes the condition which otherwise would exist in the room.

As stated above the supply air serves as the principal temperature changing medium. The remainder of the heat load is carried by a radiant panel local to the unit. This makes it possible to carry the load with a smaller volume of supply air than would be required otherwise.

Local control of heating and of cooling is effected by controlling the heat exchange local to the unit. Such control may be had in either of two ways (1) changing the rate of flow of the heat exchange liquid to some or all of the heat exchange surfaces located in the path of the supply air or (2) bypassing a graduated part of the supply air around the heat exchange surface located in the path of the supply air. In either case, so far as local control is concerned, the rate of flow of supply air remains unchanged, but the temperature which it attains is varied in relation to room temperature under the control of room thermostats or a hand operated mechanism.

The supply air after being so conditioned discharges through a long narrow slot or a conventional grille in the top of the room unit.

The local control of heating and of cooling, whether it changes the rate of flow of heat exchange liquid to surfaces in the path of supply air, or whether it controls the bypassing of air around such surfaces, always controls the flow of heat exchange liquid through the radiant panel. Under winter control it is permissible to shut down the air circulating fans while circulating heated liquid. This is a possible night and holiday setting for schools and office buildings. Under summer control it atent 2,739,792 Patented Mar. 27, 1956 is important to shut down the cold liquid circulation whenever the supply air fan is shut down. Summer control implies circulation of cold liquid both through the heat exchange coils and through the radiant panel. With supply air flowing, the room air should be so conditioned that the radiant panel will never be below the dew point of room air. With the hook-up to be described this condition is met, and the radiant panel will not sweat so long as supply air is being furnished. This condition is not assured otherwise.

The shut-downs mentioned in the preceding paragraph are not efiected by automatic'control, but are manual.

The seasonal change-over between heating and cooling functions may be effected in any known way, but manual control is adequate and is preferred for large installations. The heating of the circulating liquid is automatically controlled on a zone basis, preferably by an effective temperature instrument of conventional form subject to outdoor conditions. For simplicity the cooling of the circulating liquid can be automatically controlled on a whole building basis, preferably by a temperature instrument of conventional form subject to liquid temperature off the liquid cooler. Where a more refined control is justified the cooling of the circulating liquid can be automatically controlled on a zone basis, preferably by an effective temperature instrument of conventional form subject to outdoor conditions. The change-over mechanism whether manual or automatic, cuts-in selectively a refrigerating plant and a heating plant to cool or heat the circulating liquid, which ordinarily will be water. The liquid circulation piping requires good sealed insulation.

The distributing system for supply air requires no insula-tion Whatever. The ducts are small and suited for moderately high pressure but the system will function just as well with conventional supply ducts. The supply air is filtered, and in winter may be preheated slightly to remove the possibility of condensation of moisture on the supply air ducts. Provision is made also to heat it slightly if outside temperatures fall below a chosen minimum while the system is set for summer operation, so that the desired temperature and relative humidity can be maintained by the room units under local control.

The supply air fan may have some means responsive to head pressure and serving to control its delivery rate. In some cases this is desirable to afford regulation of supply air quantity in response to outdoor conditions or temperature. Various acceptable fan delivery controls are available.

The invention combines the proved reliability of local heat exchange surfaceto condition supply air, with the desirable feature of radiant cooling and heating. It avoids the noise and service problem inherent in the use of fans local to each unit and avoids the troublesome problems and thermal losses encountered when highly conditioned air is circulated for long distances. The supply air is cleaned and in some cases preheated before delivery to the room units and thus supplies ventilation and local cooling or heating. The distributing ducts may be small, simple and devoid of insulation.

Return ducts are unnecessary though their use is possible. It is possible in some cases to perform the liquid heating and cooling functions by relatively small units each local to a zone, or even a floor.

One of the important features of the invention is provision of an air conditioning system having an outside air supply to room units having "controls and heat exchanger surfaces so arranged that it is possible to obtain satisfactory room conditions (dry bulb temperature and relative humidity) for the seasonal range of outside conditions. In the in-between season whether the system be on summer control or winter control it is possible to heat in some rooms and cool in other rooms within a particular zone because when operating under winter control the temperature of the liquid delivered to the room units is above room temperature, while the air supplied to the room units is below room temperature. When the system is on summer control the temperature of liquid delivered to the room units is below room temperature while the temperature of the air supplied to the room units is above room temperature. This characteristic is desirable in any air conditioning system for multi-story multiroom buildings.

The invention will now be described by reference to the accompanying drawings, in which:

Fig. l is a system diagram for one zone, chiefly in elevation, but with parts of casing and duct work sectioned to disclose significant units.

Fig. 2 is a perspective view of a room unit with parts broken away to show the internal construction.

Fig. 3 is a diagram of the coils used in the unit of Fig. 2-arranged for continuous flow of liquid through one of two coils, the flow through the other coil and heat exchange panel being controlled.

Pig. 4 is a diagram similar to Fig. 3 but showing control applied to the liquid flow through both coils and heat exchange panel instead of only one coil.

Fig. 5 is a perspective view similar to Fig. 2 but showing a modified room unit in which face and bypass dampers are used to proportion air-flow in contact with the coil.

Fig. 6 is a diagram showing conjoint control of the face and bypass dampers and of flow of liquid through the heat exchange panel.

While the invention contemplates local intensive conditioning of the supply air which must be locally controlled, there is also some treatment of the supply air which is subject to general control. the system fall into two categories. It is convenient separately to describe the central system which furnishes the supply air, with its controls, then the room units, with their controls, and finally describe a typical thermostatic mechanism which may be used to actuate the controls.

Refer first to Fig. 1 which shows the essential elements of a system appropriate to an entire small building or to one zone of a large building. The practice of zoning large buildings is conventional in the heating and ventilating art.

The reference numeral 11 represents a unit for chilling Water and may be an ordinary refrigerating system of the compressor-condenser-evaporator type in which the evaporator is part of a heat exchanger which withdraws heat from water in the conditioning system. The pump 12 is the means for circulating water in the system and the unit 13 is a water heater supplied when the system operates under Winter control with. any suitable heating fluid. The unit 13 could comprise an ordinary shell-andtube exchanger with the system water passing through the tubes and the heating medium flowing through the shell outside the tubes.

The line 14 isthe supply line for the heating medium. This line is controlled by a pressure-operated valve 15 of ordinary form. A discharge connection for the heating medium is indicated at 16.

The valve shown at 17 is a three-way valve operated by pressure motor 18 and having two positions in one of which (when its motor is vented) it connects the chilled water system 11 in the circuit, and in the other of which when its motor is under pressure) it bypasses the chilled water system and excludes it from the circuit. The water heater 13 remains in the circuit but can readily be shut down by cutting oft the supply of heating medium at appropriate times.

In each room in the zone of the building covered by Figure 1 is an air conditioning unit generally designated by the numeral 21. These units will later be described indetail. To simplify Figure 1 only six such units are shown, arranged at three'dilferent levels (floors) and in two vertical tiers. Hence, in the Figure 1, there are only Hence, the controls fortwo sets of vertical supply anddischarge risers for the heat exchange water. Commonly there would be many more in one zone.

Supply risers are indicated at 22 and return risers at 23. Each unit is connected to its supply riser through a pressure operated valve 24 which in Figure l is means for controlling the rate of flow of heat exchange water to and from the unit; Each unit is provided with a drip water connection 25. All of these drips are connected to a sewer or any other drain suitable for disposing 'of drip water which collects under summer conditions as the re -Z sult of condensation of moisture from the atmosphere.

The return risers 23 are all connected at their upper ends to a return line 26 and an expansion tank 27, Whose function is familiar in the art.

The return line 26 leads to the three-way valve 17 whose function is to connect the line 26 selectively to the line 27 leading to the chilled water system 11; or tdyfth: line 28 leading directly to the intake connection offlthei circulating pump 12. The return line 29 leads from the chilled water system ll to the intake of the pump 12. Obviously, the position of the valve 17 determines whetheg:

or not the chilled water system 11 is included in the water circuit. The water heater 13 is always included in that circuit as already explained.

A relief valve 31 controls a bypass 32 connected to the intake of the pump by connection to the line 28 orin, any other suitable way, The relief valve 31 is necessary; where local control is by valves 24 because the valves 24 collectively control fiow. They may all be openor all be closed, or may assume various intermediate positions.

Since a bypass is necessary, a bypass valve which will.

operate in response to a moderate variation of pressure and hence bypass water without the development of undue back pressure is desirable. g

The pump 12 discharges through the water heater 13': and the water flows thence through the line 33 to the supply risers 34. For servicing purposes these. are;

equipped with normally closed drain valves 35.

The above completes the water circuit except for th controls of the valves 15, 17, and 24.

The entire supply air is drawn from outdoors through, the manually adjustable louver dampers 41. A possible return air connection is indicated at 42, but is shown closed by dampers 43. Connection 42 is shown to indicate the possibility of using some return air. The use of-return air, though technically possible, is unnecessary and from an economic standpoint not justifiable. At a point between the return air inlet 42 is drawn through the filter and radiator by a centrifugal.- fan 46 whose intake is shown as controlled by an adjustable louver damper 47. The louvers are actuated by a damper motor 48 of conventional form. They control the rate at which the fan 46 delivers air to the main sup-' ply duct 49. This leads to risers 51 one for each tier of room units 21. The fan maintains in the duct 21 pre s sure of the order of ten inches of water or less, a'ndis capable of propelling air through the duct systema't= speeds of the order of three thousand feet a minute; or

more.

by the duct work can be reduced and. desiiably high discharge velocities can be maintained at thedi schargc slots (hereinafter described) in the units 21.

Each of the risers 51 is connected with correspond ing units 21 by branches 52 each controlledjby a manu allyset damper 53. The dampers 53 are-for balancing the system and once set correctly are notchanged (see Figs. 2 and 5).

and the heat ing radiator 44 is an air filter 45 of ordinary form. A ir High pressure and high speed are notstrictly necesf sary, but they are desirable because the space taken up..;

value in winter, and could be uniform in summer though there are advantages to be gained by varying it under control of outdoor conditions in summer, as hereinafter described. When uniform pressures are used in summer and in winter the two uniform pressures can advantageously be different.

The supply of heating medium to the radiator 44- is controlled by a pressure-motor actuated valve 54 which is controlled by different thermostats in winter and in summer.

The preferred form of local unit 21 is shown in Fig. 2 to which reference should now be made.

These units would commonly be located under windows, but this is not essential. One or more units may be used in a room, and where more than one are located in a room they may, if desired, be subjected to common control.

The unit shown in Fig. 2 is enclosed in a metal shell 50, closed at back, front and sides. At the top there is an outlet shown as a long narrow slot 55. Conventional grilles could be substituted for the slot. A plenum chamber 60 from which slot 55 leads and to which a branch 52 leads is formed partly by the walls of shell 50 and partly by partitions 56 as clearly shown in Fig. 2. The chamber 60 is lined with sound deadening thermal insulation 57. The insulation is waterproofed at the bottom so as not to be impaired by drip water, which condenses from the supply air and is drained away by connection 25.

The chamber 60 encloses two finned heat exchange coils 58 and 59, which supply heat to or withdraw it from the supply air.

The front wall of shell 50 is removable and is marginally flanged as shown. Attached to its rear or inner face is a third coil 61, the so-called radiant coil. This is a flat zig-Zag coil devoid of fins and is mounted against the rear face of the removable front wall so as to exchange heat therewith.

As best shown in Figs. 3 and 4 coils 58 and 59 are connected in parallel to receive heating or cooling water from supply connection 22. Both discharge to connection 23, coil 58 through coil 61, and coil 59 directly.

Figs. 3 and 4 differ only in that in Figure 3 valve 24 controls flow through coils 58 and 61, coil 59 being subject to continuous flow, whereas in Fig. 4 two pressure-operated valves 24a and 24b are used, valve 24a controlling flow through coils 58 and 61 and valve 24b controlling flow through coil 59. The motors of valves 24a and 24b need not operate in unison but can have any desired sequential motion characteristics. In such event 24a should close last during winter control so as to keep the radiant coil in action. During summer control 24b remains open continuously.

The motor of valve 24 of Figure 3 and the valve motors 24a, 24b of Figure 4 are controlled by a room thermostat 62 which pilots a reversible relay 63. The relay is reversed to shift between summer and winter control. There is no difference of principle between the two arrangements but they afford somewhat different control patterns.

The unit shown in Figs. 5 and 6 is structurally similar to those above described, but differs in the fact that there is in the plenum-chamber a single coil 65 shorter than the plenum chamber, and through which the heatexchange water flows continuously. There is no local control of the flow rate. Control of heat transfer to and from the supply air is effected by face dampers 66 and by-pass dampers 67 operated simultaneously but oppositely by motor 68 through links 69 and arms 71.

Heat-exchange water enters at 72 (which corresponds to 22 on Figs. 3 and 4) and discharges at 73 to a multiway valve 74. Valve 74 directs this Water to return line 23 either through radiant coil 75 or through bypass 76 or through both in varying proportions. Valve 74 is pressure operated and it and motor 68 are controlled by thermostat 62 and reversible relay 63, the control being similar to that described as to units shown in Figs. 2-4 inclusive.

When such units are used throughout the system the flow rate of heat exchangeliquid is uniform and the relief valve 31 though desirable, is not strictly necessary.

In summer a rise in room temperature causes the room thermostat 62 to actuate motor 68 in the direction to close the by-pass and open the face dampers. When the face dampers are wide open valve 74 will direct the cold water through radiant panel coil 75. Thus control is available from a maximum when all air flows in contact with the coil and the radiant panel is fully effective to a minimum when none'or only a small portion of the air contacts coil 65 and the radiant panel coil is shut down.

In winter the thermostat'has a reverse effect so that on rising temperature, it first causes the hot water to by-pass coil 75 and then closes the face dampers while opening the by-pass dampers. The range of control is between a maximum in which all'air contacts the heating coil 65 and coil 75 is fully effective to a minimum when coil 75 is inactive and little or no air contacts coil 65. Iffan. 46 should be shut down coil 75 will furnish some heat, a possibility useful in office building installations.

The control efiected by units shown in Figs. 5 and 6 is substantially the same as can be had with the units of Figs. 24 and both are described to indicate the possi bility of choice as to control and'unit design details.

Thermostatic system Various types of thermostatic systems can be used and manufacturers of these systems can atford almost any control program that is desired. In the interest of a complete disclosure it is desired to describe the control program, and this makes it necessary to outline a typical control system.

The thermostatic system is of the pneumatic type in which changeover between winter and summer control is effected by changing the air-supply pressure.

It will be assumed that summer air pressure is 13 p. s. i. and winter air pressure 17 p. s. i. To keep the number of reference numerals to a minimum, any line and all branches in free continuous communication therewith will be given the same identifying numeral.

The air supply line 78 supplies air to the following:

(a) The relays 63 of the room thermostats 62. The change of pressure reverses the action of the relays, reversing the control to accord with heating and cooling conditions.

(b) The relay 79 of the compensated thermostat 81 which senses outdoor conditions in combination, for example, wind, sun, dry bulb temperature, etc. The relay 79 is not affected by the pressure change but requires a supply of pressure air.

(0) Relay switch-valve 82 which under winter pressure connects line 83 with line 78 and under summer pressure disconnects-and vents line 83.

(d) Relay switch-valve 84 which under winter pressure connects branch line 85 of solar relay 79 with line 86 but under summer pressure disconnects and vents line 86. When line 86 is under pressure thermostat 87 controls valve 15 through relay 88 to control the temperature of Water leaving heater 13 through line 33. When line 86 is vented the valve 15 closes.

(e) Relay switch-valve 89 which under winter pressure connects line 91 with supply line 78, and under summer pressure connects line 91 with branch line 85 of solar relay 79.

Line 83 is connected to motor 18 of the three-way valve 17 and when this line is vented as it is in summer, valve 17 connects the chilled water system in circuit.

Line 83 also serves as the air supply line for the relay 92 of master thermostat 93 which is subject to outdoor temperature and relay 94 of sub-master thermostat 95, which senses the temperature of air in duct 49. Thus these thermostats are active under Winter conditions to respond to duct temperature compensated for outdoor temperature. Pressure in line 83 pilots a relay switch valve 96 so that under winter pressure the thermostats 93 95 are connected to control steam-valve motor 54 of heater 44, through line 97. I

Under summer pressure conditions relay switch valve 96 connects the valve motor 54 with branch line 98 of relay 99 and disconnects it from line 97. This subjects valve motor 54 to control by sub-master thermostat 101 in duct 49, the control being modified by variation of pressure in branch line 85 of the solar instrument 79, to which line 91 is connected in summer by relay 89. 'Under winter pressure sub-master thermostat 101 is, disconnected atvalve 96, as explained above, and so has no effect.

The damper motor 48, which is of the graduated relay type is controlled by a pressure-sensitive unit 102 in duct 49 through static pressure regulator 103 dominated by relay switch valve 89. In winter line 91 isat supply pressure and regulator 103 maintains a uniform pressure. summer line 91 is connected with the branch line 85 of the solar instrument 79.

The solar instrument thus controls the sub-master thermostat 99, 101 and the pressure regulators 102, 103 only under summer pressure conditions. Under such conditions the solar instrument controls the steam valve 54 and damper motor 48 in' sequence in such a way that it outside temperature falls below a chosen value the .air quantity will be reduced and then the heater will be operated. V

Under winter conditions master thermostat 92, 93 and sub-master thermostat 94,- 95 assume sole control of air temperature and motor 48 responds to'constant pressure to set dampers 47 in fixed position.

To identify components above referred to they will here be identified by catalog numbers furnished by Minneapolis Honeywell Regulator Co. for their units;

Reference Catalog Name Number Number Solar Compensator 79 LOQOOA 3 Way Valve e 18 K0903B Relay Switch Valv 82. 84, 89, 96 R0492. Unit Thermostat" 63 M9040 Master Thermostat 92 L0900A Sub-master Thermostat... 94 and 99 LOQUOB Damper Motor M09003 ROMA Static Pressure Regulator r.-- 103 POQOOA What is claimed is:

1. In a multiple-room air-conditioning system, the combination of a plurality of conditioning units associated with respective rooms, each unit including means enclosing a supply air plenum having a discharge into the associated room, an air supply connection leading to the plenum, and surface heat-exchange means arranged to exchange heat with air as the latter flows through the plenum between said supply connection'and said discharge; a radiant panel heat exchanger external to said plenum and exposed to the room; a duct system for supplying air under pressure to said supply connections; means for supplying air under pressure to said duct system; and means for circulating selectively either heating or cooling liquid in a continuous path leading through at least a portion of thefirst named surface heat exchanger, and then in series through said radiant panel heat exchangen'whereby when cooling liquid is circulated it is warmed in the first named heat exchange portions, and the means for circulating heating or cooling liquid directs said liquid through the twoportions inparallel and from at least one of said-portions in'series through the radiant panel heat exchanger.

3. The combination defined in claim 1 in which the firstnamed surface heat exchange means composes two portions, the means for circulating heating or cooling liquid directs said liquid through the two portions in parallel and from at least one of said portions in series through the radiant panel heat exchanger, and means responsive to room temperature for controlling the circulation of said liquid through that portion which discharges through the radiant panel heat exchanger.

4. In a multiple-room air-conditioning system, the combination of a plurality of conditioning units associated with respective rooms, each unit including means enclosing a supply air plenum having a discharge into the associated room, an air supply connection leading to the plenum, and

surface heat-exchange means arranged to exchange heat with air as the latter flows through the plenum between said supply connection and said discharge; a radiant panel heat exchanger external to said plenum and exposed to the room; a pressure duct system for supplying air under pressure to said supply connections; means for supplying air under pressure to said duct system at a rate which is independent of room temperature; means for circulating a heat exchanging liquid through the first-named heat exchanger I and then passing at least a portion thereof in series through said radiant panel heat exchanger; and means for varying the heat exchange between the first-named heat exchanger and said air flowing through the plenum.

5. The combination defined in claim 4 in which means are provided to heat the air supplied to the duct system together with thermostatic control means therefor having a winter setting in which the air is maintained above a chosen minimum temperature sufficient to prevent condensation of atmospheric moisture on the ducts, and a summer setting in which the airfis heated only when outdoor temperature falls below achosen value.

6. A conditioning unit for supplying fresh air to a room, comprising means enclosing a plenum having a dis charge arranged to stimulate circulatory flow of air within the room; a supply connection for air under pressure leading to said plenum; surface heat exchange means arranged to exchange heat with air flowing from said supply connection through the plenum to said discharge; a radiant heat exchanger associated with the unit and external to the plenum; and connections for passing heat exchange liquid first through the exchange means in the plenum and then in series through the radiant heat exchanger.

7. A conditioning unit for supplying air to a room, comprising means enclosing a plenum having a discharge arranged to stimulate circulatory air flow within the room; means for supplying fresh air under pressure to the plenum; a surface heat exchanger in the plenum in the path of the fresh air flowing therethrough a radiant heat exchanger external to the plenum and exposed within the room; and connections for passing a refrigerating liquid through the surface heat exchanger in the plenum and then in series through the radiant heat exchanger, whereby the fresh air flowing through the plenum is cooled and dehumidified, and the refrigerating liquid fed to the radiant heat exchanger is warmed to a temperature such that the surface of the radiant heat exchanger is above the dew point temperature of the circulating room air.

References Cited in the file of this patent UNITED STATES PATENTS 1,597,774 Dodge Aug. 31, 1926 1,886,292 Modine Nov. 1, 1932' 1,922,220 Sprague Aug. 15, 1933 2,191,519 Cornell, Jr. Feb. 27, 1940 2,193,295 Otto- Mar. 12, 1940 2,212,201 Daly et al. Aug. 20, 1940 2,231,826 Foss 2d Feb. 11, 1941 2,257,975 Miller et al Oct. 7, 1941 2,463,322 Sewell et al. Mar. 1, 1949 2,675,998 Reynolds Apr. 20, 1954

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