CA1038367A - Package heat exchanger system for heating and cooling - Google Patents

Abstract

ABSTRACT

A compact heating and cooling system in which air ducts are con-nected to a heat exchanger system through which a coolant fluid from a condensing unit or a heating fluid from a compact water heater is select-ively directed by a control circuit so that the system may be mounted outside a building to be heated and/or cooled.

Description

This application is a divisional of copending Application Serial No. 150,950 filed September 5, 1972.
Combined heating and cooling systems are known in which a warm air furnace has associated therewith an air conditioning system having a cooling coil is placed in the air duct. However, such systems are essentially two complete systems, one a hot air heater which is relatively large and bulky and the other a complete air conditioner which is also relatively large and bulkyO
It is also known that a common heat exchange liquid may be pumped throughout a large building to radiators having blowers associated therewith which will either blow hot or cold air depending on whether the liquid being circulated through the radiators has been heated or cooled by remotely located boilers or air conditioners.
Package heating and cooling units are also known where electric heating coils are placed in the cooling air ducts to heat the air when desired. However, such electric heat is neither economical nor sufficient for the total heating load in many areas of the country.
According to one aspect of the present invention, there is provided a heat exchange system comprising: a source of heat comprising a burner; a first heat exchanger for transferring heat from said source to a first fluid comprising a matrix of tubular elements bonded together with a plurality of bodies providing passages for combustion products there-through, forming a thermally conductive structure rigidly interconnecting said tubular elements, and defining a central plenum surrounding said burner, a second heat exchanger for transferring heat from said first fluid to a second fluid; first conduit means for circulating said first fluid between said first heat exchanger and said second heat exchanger; second conduit means for circulating said second fluid through said second heat exchanger; external wall means surrounding said heat exchangers and sai iO:18367 conduit means; and internal wall means positioned between said first and second heat exchange means.
According to a second aspect of the present invention, there is provided a package heat exchange system comprising: first and second regions of said package substantially surrounded by exterior wall means and separated by interior wall means; a fluid circulating system extending through said interior wall means between said first and second regions within said exterior wall means; a combustion products heat exchanger located in said first region of said package for transferring thermal energy from the products of combustion to said fluid circulating system;
fluid-to-air heat exchange means positioned in said second region of said package for transferring thermal energy from said fluid circulating system to air; means in said second region for directing air through said fluid-to-air heat exchange means; and means in said first region for supplying the products of combustion to said combustion products heat exchange means comprising a burner positioned within a plenum surrounded by said combustion products heat exchanger.
The present invention in conjunction with the invention of application Serial No. 150,950 will now be described with reference to the accompanying drawings in which:
Figure 1 illustrates a top plan view of a heating and cooling system embodying this invention;
Figure 2 illustrates a side elevation view of the invention illustrated in Figure l;
Figure 3 illustrates a longitudinal sectional view of the heater illustrated in Figures 1 and 2 taken along line 3-3 of Figure 4;
Figure 4 illustrates a transverse sectional view of the heater illustrated in Figure 3 taken along line 4-4 of Figure 3;
Figure 5 illustrates an installation of the system of Figures 1 ' 1038367 through 4 in a home; and Figure 6 illustrates a schematic diagram of a control circuit for use with the system illustrated in Figures 1 through 4.
Referring now to Figures 1 through 4, there is shown a package unit 10 having a base on which are supported side walls and a top which may be made of sheet metal removably attached to an angle iron frame as in conventional package heating units.

Positioncd adjacent one side of the packago 10 approximatcly midway between the ends thereof is a compact heater unit 11.
As illustrated in greater detail in Figurcs 3 and ~, heater 11 consists of a cylindrical matrix 12 comprising a plurality of tubes 13 through which is circulated a liquid to be heated and the spaces between the tubes are filled with a plurality of spheres 14 bonded together and to the tubes to form the unitary thermally stable matrix 12. Flue gas produced by the products of combustion : from a burner 15 centrally located within the matrix is forced outwardly through the spaces between the spheres along heat ex-change paths having an average length through the matrix prefer-ably less than 20 times the average radius.of curvature of the spheres 14. Under these conditions large quantities of heat may be transferred from the burner 15 to the matrix. The liquid flowing through the tubes 13 extracts heat from the matrix to .maintain all regions of the matrix below temperatures which would damage the matrix, for example, by melting the bonds between the spheres. More specifically, if the bonds between the spheres are formed by brazing copper plated steel balls, all regions of the matrix should be maintained below 1000 F.
Fuel is supplied to the heater 11 through a solenoid con-trolled valve 16 and a pressure regulator 15a whose output is gas . at a pressure slightly below atmospheric pressure. The output of regulator 15a is fed to the input of a blower 17 driven by a blower motor 29 so that blower 17 supplies a fuel-air mixture to the burner 15 of the heater 11.
Liquid heated by the heater 11 is circulated through a pipe 18 to a heat exchangcr 19 at one end of the pack~gc 10 and thcnce .

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through a return pipe 26 to a return pump 27 which forces the fluid back through the tubes ln the heater 11. As illustrated herein, the fluid makes six passes through the heat exchanger ma-.trix 12 by reason of the upper and lower ends of tub~ 13 communi-cating with upper and lower plenums having bafflesLwhich feed the input from pump 27 to the lower ends of a first group of four of the tubes 13, and the upper ends of said first group to the upper ends of a second group of said tubes 13 whose lower ends feed a thlrd group and so on through six groups of tubes 13, with the last group feeding the heat exchanger 19 through pipe 18.
The upper end of heat exchanger coil 19 is also connected via pipe 20 to an expansion tank 21 having a vent pipe which is closed by a rubber grommet 24 having a slit 25 therein, hereinafter re-ferred to as a split web grommet,to maintain the system substan-tlally at atmospheric pressure while preventing any substantial vaporization of the liquid. The liquid may be, for example, pure water, or in the event the unit is to be mounted outside the area to be heated, a mixture of ~ater and antifreeze such as ethylene-glycol.
Ta~k 21 is positioned in a region of the package without sub-stantial heat insu7ation so th~t any vapors of the liquid which are generated in the system will condense in the tank 21. .
A blower 42 driven by a blower motor 47 is positioned in the lower portion of a space between the heater 11 and the heat ex-changer 19 which is separated lrom the region containing the heater 11 by a transverse wall 43. Blower 42 exhausts air through a horizontal wall 45 and thus draws air through fins 41 connected to heat exchanger coil 19 from a cold air return duct 40 which is connected to the system 10 adjacent heat exchanger 19. A duct 46 is connected to the outlet at the end of the package 10 above the ~ 1038367 duct 40 and conducts air which has been drawn over heat exchanger 19 back into the home to heat the home. The walls of the compart-ment containing the blower 42 may be insulated with insulating material (not shown) to prevent heat transfer of the air to the outside region of the system 10 and to absorb noise from the blow-er 42. As illustrated herein wall 43 separates the region con-talning the expansion tank 21 from the region into which blower 42 exhausts so that tank 21 may be maintained cooler than the output region from the blower 42 hence aiding in condensing any vapors produced in the heater system and entering the tank 21 th~ ugh the pipe 20.
To provide for cooling the air blown into duct 46 by blower 42, for air conditioning, a cooling compressor 60 is provided on the opposite side of the cabinet from the heater 11. The compres-sor is of a conventional air conditioning type which compresses a refrigerant working fluid such as freon and supplies it through a pipe 61 to a condenser 62 of conventional type consisting of tubes and ~ins. Condenser 62 is positioned on the opposite end ~ the system 10 from the heatlng coil 19 and thus is exposed to the open ~0 air. A pipe 63 supplies cooled freon from condenser coil 62 to a freon expansion coil 64 whlch is attached to the same fin structure 41 as the coil 19 so that air passing from the intake duct 40 by the fins 41 will be cooled by the coil 64 when the compressor 60 is operating. The freon from coil 64 is then returned to compres-sor 60 by a return pipe. Additional components such as expansion valves and freon filter-driers may also be incorporated in the -- system in accordance with well-known practice.
By using the same set of fins 41 for both the heating coil 19, and the cooling coil 64; the resistance to air flow and hence the iO blower power required by the motor 47 driving the blower 42 is mlnimized since essentlally the same iin area ls required whether the alr is being cooled or heated. If desired, of course, separ-ate heat exchanger units with separate fins may be used in place of the coils 64 and 19 with the common fins 41. In addition, if desired, one of the coils such as, for example, the heating coil 19 may be placed in the upper compartment after thé air has been blown up by the blower 42.
The condenser coil 62 has alr blown over it i'rom lnside the unlt 10 by means of a fan 65 driven by a motor 66. As illustrated herein, the fan 65 is mounted in a surrounding shroud 67 to improve ~an efficiency.
Vents 68 on the sides of the package 10 in the region occupied by the heater 11 and the compressor 60 provide an air intake for burner blower 17 and~or air for fan 65 which also maintains com-pressor 60 in a condition where operation will not overheat it.
Referring now to Figure 5, there is shown a typical instal-lation of a package unit 10 in a home having a gabled roof. The package 10 mounted on the side thereof facing the back of the house and the ducts 40 and 46 are connected through the roof of the house into the attic. As illustrated herein, the duct 46 sup-plies air to the various rooms of the house through a distribution duct work system blowing the air which has been heated or cooled through the ceiling at the center of each room. The return air is collected by a central duct feeding the duct 40. Gas for the heat-er 11 may come from a utility supply or from a storage tank at the back of the house from which a pipe is fed to the system 10 on the roof. The package unit 10 may alternatively be connected through the wall at the back of the house, may be set in a recess in the wall, may be placed in the basement or in a pit or on a slab at the side or back of the house. In the case of commercial instal-. .

lations or on other structures having flat roofs, the unit 10 maybe placed on the roof.
Referring now to Figure 6, there is shown a control circuit for the package unit 10. Power is supplied to lines 80 and 81 from a power supply system. As illustrated herein, the voltage on lines 80 and 81 may be, for example, a conventional 240 volt 60 cycle AC supply which in the case of conventional home power systems will have a voltage at 120 volts with respect to ground applied to each of the wires 80 and 81. A crankcase heater for compressor 60 is connected directly across lines 80 and 81 so that whenever power is available to the package unit, sufficient heat - is supplied to the compressor crankcase to maintain the oil in the crankcase substantially free of condensed refrigerant. By this means, the compressor w111 be maintained in a lubricated con-dition during operation whereas if refrigerant had been allowed to dissolve in the oil, upon starting of the compressor, the oil would foam thereby decreasing its lubricating ability.
The temperature in the area being heated or cooled is con-trolled by means of a thermostat 83 positioned in an area such as a room of the home. Thermostat 83 comprises two temperature con-trol switches which, in accordance with well-known practice, are adjustable to various temperatures dependent on the mechanical setting of a bellows or bimetallic strip linkage. As illustrated herein, the thermostat 88 controls the cooling system and the thermostat 89 controls the heating system. The thermostat 83 is in a low voltage circuit supplied from lines 80 and 81 by means of a transformer 86 whose primary 87 is connected across lines 80 and 81 and whose secondary line 85 supplies a lower voltage of, for example, 24 v~lts to the thermostat control circuit. More specif-ically one end of winding 85 is connected through a fuse 84 to a common terminal o~ switches 88 and 89. The other end of winding85 is connected through a thermostatically controlled limit switch 98 to a burner control unit 99 and to one end of a heater control relay coil 93. ~he other terminal of switch 89 is connected to a terminal 91 of a manually operated heat-cool selection switch 90 which when set in the "heat" position connects terminal 91 to ter-minal 92 which in turn is connected to the other end of the relay coil 93. Terminal 92 also feeds the other power input of the burner control unit 99.
Switch 89 ls operated by a mechanical temperature sensing device o~ any desired type such as a bimetallic strip or as illus-trated herein by a bellows and is designed to open when the tem-perature reaches the desired level in the room to be heated. When the temperature drops below the desired level switch 89 closes energizing relay control winding 93 which closes relay contacts 93a thereb~ connecting a pump motor 28 which drives pump 27 across the lines 80 and ~1. Blower motor 47 driving blower 42 is also energized by contacts 93a which connect high speed winding 94 of motor 47 and its starting winding 95 fed by a condenser 96 across lines 80 and 81.
Contacts 93a are in parallel with a water temperature control switch 97 which is placed on the line 18 to sense the temperature of the water as it comes out of the heater 11. The temperature at which switch 97 closes is made, for example, 100F. so that when the thermostat switch 89 has er.ergized the system to produce heat from the heater 11 and the water, which is circulating since con-tacts 93a are closed, has risen above 100F. switch 97 will close and thereafter when the burner for the heater 11 shuts down, the pump motor 28 and blower motor 47 will continue to run until the temperature of the water emerging from the heater falls below 100F.

Thus all of the heat above 100F. which has been stored in the heater 11 due to the metal heat sink effect is transferred to the air being circulated through the ducts 40 and 46. In addition, since some portions thereof are substantially hotter than the liquid, the heat in the heater 11 must be removed or it will va-porize some of the liquid in the tubes 13 thereby driving portions of the fluid out the vent 25 and in addition opening limit switch 98 in the heater 11 which is set at a temperature of, for examplet 200F. Limit switch 98 would not reclose until the heat in the heater 11 had been dissipated by radiation, thereby increasing the recycle time of the heater.
The burner control module 99 may be of any desired conven-tional type and as illustrated herein comprises an ignition trans-former 100 feeding an igniter spark plug 101 in heater 11. The solenoid of gas valve 16 is also fed by a control circuit of the burner control system 99 such that when switch 89 closes, gas valve 16 opens supplying gas to the regulator 15. When blower 17 starts it draws a relatively small flow of gas through the regula-tor 15 and as it comes up to speed and blows the full amount of ~0 air called for by the burner more gas passes through the regulator lS and mixes with the air being blown into the burner by the blow-er 17. Thus the gas-air mixture remains relatively constant .
independent of the speed of the blower, the burner does not start with an overrich supply of air-fuel mixture so that there is sub-stantially no carbonization of the heater matrix 12 and no smoke appears at the output vent 32.
Since the opening of limit switch 98 shuts down both the control module 99 and the relay 93 controlling the blower motor 28, there is a double or redundant fail-safe action. If, for ~0 example, the gas valve 16 were to remain open when the control _ 10 _ I

: 1038367 system 99 de-energized the solenoid of the valve 16, for example, due to sticking of the valve, the burner blower motor 28 would be-also de-energized by opening relay contacts 93b and therefore no gas would flow into the heater. Thus, there is both an elec-trical and a mechanical fail-safe system associated with the burner system.
When it is desired to operate the package unit as a cooling system, the manually operated selector switch 90 is placed in the cool position and under these conditions a contact 110 which is connected to the other terminal of cooling thermostat switch 88 ~rom ~hat connected to fuse 84 is connected to a contact 111 of switch 90 which is connected through a compressor control relay coil 112 to the junction between limit switch 98 and transformer secondary winding 85. This energizes relay coil 112 which closes contacts 112a and 112b and energizes compressor motor 120 from buses 80 and 81. As illustrated herein, the compressor motor is a conventional capacitor start and run single phase motor having a conventional overload switch associated therewith. Connected in parallel with compressor motor 120 is motor 66 which drives fan 65 to blow air over the condenser coil 62 so that whenever the compressor 60 is running the fan 65 is drawing air over the compressor 60 to ensure that it does not overheat and blowing the air over the condenser coil 62 to cool the compressed refrigerant being pumped thereto.
Terminal 111 of switch 90 is also connected via a terminal 113 to a manually operated automatic-manual switch 114 for con-trolling the blower 42. In the automatic position, a relay coil 116 is energized via switch 114 by connecting terminal 113 of switch 114 to terminal 115 of switch 114 thereby closing relay 3~ contacts 116a to energize a low speed winding 94a of motor 47.

~038367 Thus when the thermostat switch 88 closes when the temperature in the room rises above a pre-selected value the compressor will start and the fan and the blower 42 will run at a reduced speed to circulate cooled air through the ducts 40 and 46. The blower 42 is run at a reduced speed during cooling since the amount of heat being transferred during cooling is usually less than that required for peak heating loads. For example, the unit illustrated herein transfers 30 to 40,000 BTU's per hour during cooling and 100,000 BTU's per hour or more during heating.
For continuous operation of the blower ~ without thermostat-ic control, switch 114 is switched to the manual position so that relay coil 116 is energized by connection of contact 115 of switch 114 to terminal 117 of switch 114 which is connected directly to fuse 84 thereby bypassing the thermostat switch 88.
In this mode of operation the air will continuously circulate through the area being heated or cooled even when no heating or coollng is being supplied to the heat exchanger coils 19 or 64.
This concludes the description of the preferred embodiment of the invention illustrated herein, however, many modifications thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. For example, a compact unit as illustrated herein can use a compact heater circulating fluid to a heat exchanger positioned adjacent the unit which heats hot air for supply to a building to be heat-ed without the installation of a condensing unit for cooling.
In addition, heating fluid other than a liquid may be used such as steam or vapor of other fluids than water. Other means of supplying a cooling system could be used such as an adsorption heat pump system which could use the heat from the heater 11.
Also, systems may be used in which the circulating pump ~or the _ 12 _ liquid is eliminated and the system can be designed to operate at any desired pressure by selection oi' the fluid to be circu-lated through the heater. Furthermore, many modifications of the control circuitry may be made to achieve the control i'unctions set forth in this invention. Accordingly, it is intended that this invention not be limited to the particular details disclosed herein except as defined by the appended claims.

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Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heat exchange system comprising: a source of heat comprising a burner; a first heat exchanger for transferring heat from said source to a first fluid comprising a matrix of tubular elements bonded together with a plurality of bodies providing passages for combustion products therethrough, forming a thermally conductive structure rigidly interconnect-ing said tubular elements, and defining a central plenum surrounding said burner; a second heat exchanger for transferring heat from said first fluid to a second fluid; first conduit means for circulating said first fluid between said first heat exchanger and said second heat exchanger; second conduit means for circulating said second fluid through said second heat exchanger; external wall means surrounding said heat exchangers and said conduit means; and internal wall means positioned between said first and second heat exchange means.

2. The heat exchange system in accordance with Claim 1 wherein said first fluid is a liquid.

3. The heat exchange system in accordance with Claim 2 wherein said liquid is maintained substantially at or below atmospheric pressure.

4. The heat exchange system in accordance with Claim 3 wherein said source of heat comprises a burner having a blower connected thereto; and means for supplying the input to said blower with air and a gaseous fuel.

5. The heat exchange system in accordance with Claim 2 wherein said first and second heat exchangers are mounted in spaced relationship in a package unit; at least one of said heat exchangers comprising a plurality of bodies having predominantly curved surfaces bonded together with a plurality of tubular elements to provide passages for combustion products therethrough wherein the average length of said passages is less than 20 times the average radius of curvature of the surfaces of said bodies.

6. The heat exchange system in accordance with Claim 1 wherein circulation of said fluids through said heat exchangers is provided whenever the temperature of said first fluid is above a preselected value.

7. The heat exchange system in accordance with Claim 6 wherein said preselected value of said temperature is below the boiling point of said first fluid at the pressure of said first fluid in said first heat exchanger.

8. The heat exchange system in accordance with Claim 1 and control means for controlling said circulation of said first fluid and said second fluid through said second heat exchanger.

9. The heat exchange system in accordance with Claim 8 wherein said control means comprises a thermostatically controlled switch.

10. The heat exchange system in accordance with Claim 1 wherein said source of heat comprises a burner positioned in heat exchanging relation with said matrix having a control circuit controlled at least in part by the temperature of said second fluid and at least in part by the temperature of said first fluid.

11. The heat exchange system in accordance with Claim 10 wherein said burner is positioned within a plenum surrounded by said matrix and is supplied with a gaseous fuel-air mixture through a blower controlled at least in part by means for determining the presence of a flame in said plenum.

12. A package heat exchange system comprising: first and second regions of said package substantially surrounded by exterior wall means and separated by interior wall means; a fluid circulating system extending through said interior wall means between said first and second regions within said exterior wall means; a combustion products heat exchanger located in said first region of said package for transferring thermal energy from the products of combustion to said fluid circulating system;
fluid-to-air heat exchange means positioned in said second region of said package for transferring thermal energy from said fluid circulating system to air; means in said second region for directing air through said fluid-to-air heat exchange means; and means in said first region for supplying the products of combustion to said combustion products heat exchange means comprising a burner positioned within a plenum surrounded by said combustion products heat exchanger.

13. The package heat exchange system in accordance with Claim 12 wherein: said combustion products heat exchanger comprises a plurality of tubular elements surrounding a central plenum; and a plurality of thermally conductive elements rigidly interconnecting said tubular elements.

14. The package heat exchange system in accordance with Claim 13 wherein: said means for producing the products of combustion comprises a burner positioned within said central plenum.

15. The package heat exchange system in accordance with Claim 12 wherein: said fluid-to-air heat exchanger is positioned adjacent an exterior wall of said package.

16. The package heat exchange system in accordance with Claim 15 wherein: air ducts are connected to said exterior wall means of said package for conducting air to said first region for direction through said fluid-to-air heat exchange means.

17. The package heat exchange system in accordance with Claim 12 wherein: said fluid circulating system comprises a fluid compound, and said combustion products heat exchanger has a surface area contacting said products of combustion which is substantially greater than the surface area of said combustion products heat exchanger contacting said fluid compound.

18. The package heat exchange system in accordance with Claim 17 wherein: said fluid circulating system comprises means for circulating said fluid compound through a plurality of conduits extending between said air heat exchanger and said combustion products heat exchanger through said wall means.